Added missing tegra files.HEADmaster

12 files changed, 7984 insertions, 0 deletions

diff --git a/drivers/staging/pohmelfs/Kconfig b/drivers/staging/pohmelfs/Kconfig
new file mode 100644
index 00000000000..58158b8780f
--- /dev/null
+++ b/drivers/staging/pohmelfs/Kconfig
@@ -0,0 +1,28 @@
+config POHMELFS
+        tristate "POHMELFS filesystem support"
+        depends on NET
+        select CONNECTOR
+        select CRYPTO
+        select CRYPTO_BLKCIPHER
+        select CRYPTO_HMAC
+        help
+          POHMELFS stands for Parallel Optimized Host Message Exchange Layered
+          File System.  This is a network filesystem which supports coherent
+          caching of data and metadata on clients.
+
+config POHMELFS_DEBUG
+        bool "POHMELFS debugging"
+        depends on POHMELFS
+        default n
+        help
+          Turns on excessive POHMELFS debugging facilities.
+          You usually do not want to slow things down noticeably and get really
+          lots of kernel messages in syslog.
+
+config POHMELFS_CRYPTO
+        bool "POHMELFS crypto support"
+        depends on POHMELFS
+        help
+          This option allows to encrypt and/or protect with strong
+          cryptographic hash all dataflow between server and clients.
+          Each config group can have its own keys.
diff --git a/drivers/staging/pohmelfs/Makefile b/drivers/staging/pohmelfs/Makefile
new file mode 100644
index 00000000000..196561ca26b
--- /dev/null
+++ b/drivers/staging/pohmelfs/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_POHMELFS)  += pohmelfs.o
+
+pohmelfs-y := inode.o config.o dir.o net.o path_entry.o trans.o crypto.o lock.o mcache.o
diff --git a/drivers/staging/pohmelfs/config.c b/drivers/staging/pohmelfs/config.c
new file mode 100644
index 00000000000..b6c42cb0d1c
--- /dev/null
+++ b/drivers/staging/pohmelfs/config.c
@@ -0,0 +1,611 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/connector.h>
+#include <linux/crypto.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/string.h>
+#include <linux/in.h>
+#include <linux/slab.h>
+
+#include "netfs.h"
+
+/*
+ * Global configuration list.
+ * Each client can be asked to get one of them.
+ *
+ * Allows to provide remote server address (ipv4/v6/whatever), port
+ * and so on via kernel connector.
+ */
+
+static struct cb_id pohmelfs_cn_id = {.idx = POHMELFS_CN_IDX, .val = POHMELFS_CN_VAL};
+static LIST_HEAD(pohmelfs_config_list);
+static DEFINE_MUTEX(pohmelfs_config_lock);
+
+static inline int pohmelfs_config_eql(struct pohmelfs_ctl *sc, struct pohmelfs_ctl *ctl)
+{
+        if (sc->idx == ctl->idx && sc->type == ctl->type &&
+                        sc->proto == ctl->proto &&
+                        sc->addrlen == ctl->addrlen &&
+                        !memcmp(&sc->addr, &ctl->addr, ctl->addrlen))
+                return 1;
+
+        return 0;
+}
+
+static struct pohmelfs_config_group *pohmelfs_find_config_group(unsigned int idx)
+{
+        struct pohmelfs_config_group *g, *group = NULL;
+
+        list_for_each_entry(g, &pohmelfs_config_list, group_entry) {
+                if (g->idx == idx) {
+                        group = g;
+                        break;
+                }
+        }
+
+        return group;
+}
+
+static struct pohmelfs_config_group *pohmelfs_find_create_config_group(unsigned int idx)
+{
+        struct pohmelfs_config_group *g;
+
+        g = pohmelfs_find_config_group(idx);
+        if (g)
+                return g;
+
+        g = kzalloc(sizeof(struct pohmelfs_config_group), GFP_KERNEL);
+        if (!g)
+                return NULL;
+
+        INIT_LIST_HEAD(&g->config_list);
+        g->idx = idx;
+        g->num_entry = 0;
+
+        list_add_tail(&g->group_entry, &pohmelfs_config_list);
+
+        return g;
+}
+
+static inline void pohmelfs_insert_config_entry(struct pohmelfs_sb *psb, struct pohmelfs_config *dst)
+{
+        struct pohmelfs_config *tmp;
+
+        INIT_LIST_HEAD(&dst->config_entry);
+
+        list_for_each_entry(tmp, &psb->state_list, config_entry) {
+                if (dst->state.ctl.prio > tmp->state.ctl.prio)
+                        list_add_tail(&dst->config_entry, &tmp->config_entry);
+        }
+        if (list_empty(&dst->config_entry))
+                list_add_tail(&dst->config_entry, &psb->state_list);
+}
+
+static int pohmelfs_move_config_entry(struct pohmelfs_sb *psb,
+                struct pohmelfs_config *dst, struct pohmelfs_config *new)
+{
+        if ((dst->state.ctl.prio == new->state.ctl.prio) &&
+                (dst->state.ctl.perm == new->state.ctl.perm))
+                return 0;
+
+        dprintk("%s: dst: prio: %d, perm: %x, new: prio: %d, perm: %d.\n",
+                        __func__, dst->state.ctl.prio, dst->state.ctl.perm,
+                        new->state.ctl.prio, new->state.ctl.perm);
+        dst->state.ctl.prio = new->state.ctl.prio;
+        dst->state.ctl.perm = new->state.ctl.perm;
+
+        list_del_init(&dst->config_entry);
+        pohmelfs_insert_config_entry(psb, dst);
+        return 0;
+}
+
+/*
+ * pohmelfs_copy_config() is used to copy new state configs from the
+ * config group (controlled by the netlink messages) into the superblock.
+ * This happens either at startup time where no transactions can access
+ * the list of the configs (and thus list of the network states), or at
+ * run-time, where it is protected by the psb->state_lock.
+ */
+int pohmelfs_copy_config(struct pohmelfs_sb *psb)
+{
+        struct pohmelfs_config_group *g;
+        struct pohmelfs_config *c, *dst;
+        int err = -ENODEV;
+
+        mutex_lock(&pohmelfs_config_lock);
+
+        g = pohmelfs_find_config_group(psb->idx);
+        if (!g)
+                goto out_unlock;
+
+        /*
+         * Run over all entries in given config group and try to create and
+         * initialize those, which do not exist in superblock list.
+         * Skip all existing entries.
+         */
+
+        list_for_each_entry(c, &g->config_list, config_entry) {
+                err = 0;
+                list_for_each_entry(dst, &psb->state_list, config_entry) {
+                        if (pohmelfs_config_eql(&dst->state.ctl, &c->state.ctl)) {
+                                err = pohmelfs_move_config_entry(psb, dst, c);
+                                if (!err)
+                                        err = -EEXIST;
+                                break;
+                        }
+                }
+
+                if (err)
+                        continue;
+
+                dst = kzalloc(sizeof(struct pohmelfs_config), GFP_KERNEL);
+                if (!dst) {
+                        err = -ENOMEM;
+                        break;
+                }
+
+                memcpy(&dst->state.ctl, &c->state.ctl, sizeof(struct pohmelfs_ctl));
+
+                pohmelfs_insert_config_entry(psb, dst);
+
+                err = pohmelfs_state_init_one(psb, dst);
+                if (err) {
+                        list_del(&dst->config_entry);
+                        kfree(dst);
+                }
+
+                err = 0;
+        }
+
+out_unlock:
+        mutex_unlock(&pohmelfs_config_lock);
+
+        return err;
+}
+
+int pohmelfs_copy_crypto(struct pohmelfs_sb *psb)
+{
+        struct pohmelfs_config_group *g;
+        int err = -ENOENT;
+
+        mutex_lock(&pohmelfs_config_lock);
+        g = pohmelfs_find_config_group(psb->idx);
+        if (!g)
+                goto err_out_exit;
+
+        if (g->hash_string) {
+                err = -ENOMEM;
+                psb->hash_string = kstrdup(g->hash_string, GFP_KERNEL);
+                if (!psb->hash_string)
+                        goto err_out_exit;
+                psb->hash_strlen = g->hash_strlen;
+        }
+
+        if (g->cipher_string) {
+                psb->cipher_string = kstrdup(g->cipher_string, GFP_KERNEL);
+                if (!psb->cipher_string)
+                        goto err_out_free_hash_string;
+                psb->cipher_strlen = g->cipher_strlen;
+        }
+
+        if (g->hash_keysize) {
+                psb->hash_key = kmemdup(g->hash_key, g->hash_keysize,
+                                        GFP_KERNEL);
+                if (!psb->hash_key)
+                        goto err_out_free_cipher_string;
+                psb->hash_keysize = g->hash_keysize;
+        }
+
+        if (g->cipher_keysize) {
+                psb->cipher_key = kmemdup(g->cipher_key, g->cipher_keysize,
+                                          GFP_KERNEL);
+                if (!psb->cipher_key)
+                        goto err_out_free_hash;
+                psb->cipher_keysize = g->cipher_keysize;
+        }
+
+        mutex_unlock(&pohmelfs_config_lock);
+
+        return 0;
+
+err_out_free_hash:
+        kfree(psb->hash_key);
+err_out_free_cipher_string:
+        kfree(psb->cipher_string);
+err_out_free_hash_string:
+        kfree(psb->hash_string);
+err_out_exit:
+        mutex_unlock(&pohmelfs_config_lock);
+        return err;
+}
+
+static int pohmelfs_send_reply(int err, int msg_num, int action, struct cn_msg *msg, struct pohmelfs_ctl *ctl)
+{
+        struct pohmelfs_cn_ack *ack;
+
+        ack = kzalloc(sizeof(struct pohmelfs_cn_ack), GFP_KERNEL);
+        if (!ack)
+                return -ENOMEM;
+
+        memcpy(&ack->msg, msg, sizeof(struct cn_msg));
+
+        if (action == POHMELFS_CTLINFO_ACK)
+                memcpy(&ack->ctl, ctl, sizeof(struct pohmelfs_ctl));
+
+        ack->msg.len = sizeof(struct pohmelfs_cn_ack) - sizeof(struct cn_msg);
+        ack->msg.ack = msg->ack + 1;
+        ack->error = err;
+        ack->msg_num = msg_num;
+
+        cn_netlink_send(&ack->msg, 0, GFP_KERNEL);
+        kfree(ack);
+        return 0;
+}
+
+static int pohmelfs_cn_disp(struct cn_msg *msg)
+{
+        struct pohmelfs_config_group *g;
+        struct pohmelfs_ctl *ctl = (struct pohmelfs_ctl *)msg->data;
+        struct pohmelfs_config *c, *tmp;
+        int err = 0, i = 1;
+
+        if (msg->len != sizeof(struct pohmelfs_ctl))
+                return -EBADMSG;
+
+        mutex_lock(&pohmelfs_config_lock);
+
+        g = pohmelfs_find_config_group(ctl->idx);
+        if (!g) {
+                pohmelfs_send_reply(err, 0, POHMELFS_NOINFO_ACK, msg, NULL);
+                goto out_unlock;
+        }
+
+        list_for_each_entry_safe(c, tmp, &g->config_list, config_entry) {
+                struct pohmelfs_ctl *sc = &c->state.ctl;
+                if (pohmelfs_send_reply(err, g->num_entry - i, POHMELFS_CTLINFO_ACK, msg, sc)) {
+                        err = -ENOMEM;
+                        goto out_unlock;
+                }
+                i += 1;
+        }
+
+ out_unlock:
+        mutex_unlock(&pohmelfs_config_lock);
+        return err;
+}
+
+static int pohmelfs_cn_dump(struct cn_msg *msg)
+{
+        struct pohmelfs_config_group *g;
+        struct pohmelfs_config *c, *tmp;
+        int err = 0, i = 1;
+        int total_msg = 0;
+
+        if (msg->len != sizeof(struct pohmelfs_ctl))
+                return -EBADMSG;
+
+        mutex_lock(&pohmelfs_config_lock);
+
+        list_for_each_entry(g, &pohmelfs_config_list, group_entry)
+                total_msg += g->num_entry;
+        if (total_msg == 0) {
+                if (pohmelfs_send_reply(err, 0, POHMELFS_NOINFO_ACK, msg, NULL))
+                        err = -ENOMEM;
+                goto out_unlock;
+        }
+
+        list_for_each_entry(g, &pohmelfs_config_list, group_entry) {
+                list_for_each_entry_safe(c, tmp, &g->config_list,
+                                         config_entry) {
+                        struct pohmelfs_ctl *sc = &c->state.ctl;
+                        if (pohmelfs_send_reply(err, total_msg - i,
+                                                POHMELFS_CTLINFO_ACK, msg,
+                                                sc)) {
+                                err = -ENOMEM;
+                                goto out_unlock;
+                        }
+                        i += 1;
+                }
+        }
+
+out_unlock:
+        mutex_unlock(&pohmelfs_config_lock);
+        return err;
+}
+
+static int pohmelfs_cn_flush(struct cn_msg *msg)
+{
+        struct pohmelfs_config_group *g;
+        struct pohmelfs_ctl *ctl = (struct pohmelfs_ctl *)msg->data;
+        struct pohmelfs_config *c, *tmp;
+        int err = 0;
+
+        if (msg->len != sizeof(struct pohmelfs_ctl))
+                return -EBADMSG;
+
+        mutex_lock(&pohmelfs_config_lock);
+
+        if (ctl->idx != POHMELFS_NULL_IDX) {
+                g = pohmelfs_find_config_group(ctl->idx);
+
+                if (!g)
+                        goto out_unlock;
+
+                list_for_each_entry_safe(c, tmp, &g->config_list, config_entry) {
+                        list_del(&c->config_entry);
+                        g->num_entry--;
+                        kfree(c);
+                }
+        } else {
+                list_for_each_entry(g, &pohmelfs_config_list, group_entry) {
+                        list_for_each_entry_safe(c, tmp, &g->config_list,
+                                                 config_entry) {
+                                list_del(&c->config_entry);
+                                g->num_entry--;
+                                kfree(c);
+                        }
+                }
+        }
+
+out_unlock:
+        mutex_unlock(&pohmelfs_config_lock);
+        pohmelfs_cn_dump(msg);
+
+        return err;
+}
+
+static int pohmelfs_modify_config(struct pohmelfs_ctl *old, struct pohmelfs_ctl *new)
+{
+        old->perm = new->perm;
+        old->prio = new->prio;
+        return 0;
+}
+
+static int pohmelfs_cn_ctl(struct cn_msg *msg, int action)
+{
+        struct pohmelfs_config_group *g;
+        struct pohmelfs_ctl *ctl = (struct pohmelfs_ctl *)msg->data;
+        struct pohmelfs_config *c, *tmp;
+        int err = 0;
+
+        if (msg->len != sizeof(struct pohmelfs_ctl))
+                return -EBADMSG;
+
+        mutex_lock(&pohmelfs_config_lock);
+
+        g = pohmelfs_find_create_config_group(ctl->idx);
+        if (!g) {
+                err = -ENOMEM;
+                goto out_unlock;
+        }
+
+        list_for_each_entry_safe(c, tmp, &g->config_list, config_entry) {
+                struct pohmelfs_ctl *sc = &c->state.ctl;
+
+                if (pohmelfs_config_eql(sc, ctl)) {
+                        if (action == POHMELFS_FLAGS_ADD) {
+                                err = -EEXIST;
+                                goto out_unlock;
+                        } else if (action == POHMELFS_FLAGS_DEL) {
+                                list_del(&c->config_entry);
+                                g->num_entry--;
+                                kfree(c);
+                                goto out_unlock;
+                        } else if (action == POHMELFS_FLAGS_MODIFY) {
+                                err = pohmelfs_modify_config(sc, ctl);
+                                goto out_unlock;
+                        } else {
+                                err = -EEXIST;
+                                goto out_unlock;
+                        }
+                }
+        }
+        if (action == POHMELFS_FLAGS_DEL) {
+                err = -EBADMSG;
+                goto out_unlock;
+        }
+
+        c = kzalloc(sizeof(struct pohmelfs_config), GFP_KERNEL);
+        if (!c) {
+                err = -ENOMEM;
+                goto out_unlock;
+        }
+        memcpy(&c->state.ctl, ctl, sizeof(struct pohmelfs_ctl));
+        g->num_entry++;
+
+        list_add_tail(&c->config_entry, &g->config_list);
+
+ out_unlock:
+        mutex_unlock(&pohmelfs_config_lock);
+        if (pohmelfs_send_reply(err, 0, POHMELFS_NOINFO_ACK, msg, NULL))
+                err = -ENOMEM;
+
+        return err;
+}
+
+static int pohmelfs_crypto_hash_init(struct pohmelfs_config_group *g, struct pohmelfs_crypto *c)
+{
+        char *algo = (char *)c->data;
+        u8 *key = (u8 *)(algo + c->strlen);
+
+        if (g->hash_string)
+                return -EEXIST;
+
+        g->hash_string = kstrdup(algo, GFP_KERNEL);
+        if (!g->hash_string)
+                return -ENOMEM;
+        g->hash_strlen = c->strlen;
+        g->hash_keysize = c->keysize;
+
+        g->hash_key = kmemdup(key, c->keysize, GFP_KERNEL);
+        if (!g->hash_key) {
+                kfree(g->hash_string);
+                return -ENOMEM;
+        }
+
+        return 0;
+}
+
+static int pohmelfs_crypto_cipher_init(struct pohmelfs_config_group *g, struct pohmelfs_crypto *c)
+{
+        char *algo = (char *)c->data;
+        u8 *key = (u8 *)(algo + c->strlen);
+
+        if (g->cipher_string)
+                return -EEXIST;
+
+        g->cipher_string = kstrdup(algo, GFP_KERNEL);
+        if (!g->cipher_string)
+                return -ENOMEM;
+        g->cipher_strlen = c->strlen;
+        g->cipher_keysize = c->keysize;
+
+        g->cipher_key = kmemdup(key, c->keysize, GFP_KERNEL);
+        if (!g->cipher_key) {
+                kfree(g->cipher_string);
+                return -ENOMEM;
+        }
+
+        return 0;
+}
+
+static int pohmelfs_cn_crypto(struct cn_msg *msg)
+{
+        struct pohmelfs_crypto *crypto = (struct pohmelfs_crypto *)msg->data;
+        struct pohmelfs_config_group *g;
+        int err = 0;
+
+        dprintk("%s: idx: %u, strlen: %u, type: %u, keysize: %u, algo: %s.\n",
+                        __func__, crypto->idx, crypto->strlen, crypto->type,
+                        crypto->keysize, (char *)crypto->data);
+
+        mutex_lock(&pohmelfs_config_lock);
+        g = pohmelfs_find_create_config_group(crypto->idx);
+        if (!g) {
+                err = -ENOMEM;
+                goto out_unlock;
+        }
+
+        switch (crypto->type) {
+        case POHMELFS_CRYPTO_HASH:
+                        err = pohmelfs_crypto_hash_init(g, crypto);
+                        break;
+        case POHMELFS_CRYPTO_CIPHER:
+                        err = pohmelfs_crypto_cipher_init(g, crypto);
+                        break;
+        default:
+                        err = -ENOTSUPP;
+                        break;
+        }
+
+out_unlock:
+        mutex_unlock(&pohmelfs_config_lock);
+        if (pohmelfs_send_reply(err, 0, POHMELFS_NOINFO_ACK, msg, NULL))
+                err = -ENOMEM;
+
+        return err;
+}
+
+static void pohmelfs_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
+{
+        int err;
+
+        if (!cap_raised(current_cap(), CAP_SYS_ADMIN))
+                return;
+
+        switch (msg->flags) {
+        case POHMELFS_FLAGS_ADD:
+        case POHMELFS_FLAGS_DEL:
+        case POHMELFS_FLAGS_MODIFY:
+                        err = pohmelfs_cn_ctl(msg, msg->flags);
+                        break;
+        case POHMELFS_FLAGS_FLUSH:
+                        err = pohmelfs_cn_flush(msg);
+                        break;
+        case POHMELFS_FLAGS_SHOW:
+                        err = pohmelfs_cn_disp(msg);
+                        break;
+        case POHMELFS_FLAGS_DUMP:
+                        err = pohmelfs_cn_dump(msg);
+                        break;
+        case POHMELFS_FLAGS_CRYPTO:
+                        err = pohmelfs_cn_crypto(msg);
+                        break;
+        default:
+                        err = -ENOSYS;
+                        break;
+        }
+}
+
+int pohmelfs_config_check(struct pohmelfs_config *config, int idx)
+{
+        struct pohmelfs_ctl *ctl = &config->state.ctl;
+        struct pohmelfs_config *tmp;
+        int err = -ENOENT;
+        struct pohmelfs_ctl *sc;
+        struct pohmelfs_config_group *g;
+
+        mutex_lock(&pohmelfs_config_lock);
+
+        g = pohmelfs_find_config_group(ctl->idx);
+        if (g) {
+                list_for_each_entry(tmp, &g->config_list, config_entry) {
+                        sc = &tmp->state.ctl;
+
+                        if (pohmelfs_config_eql(sc, ctl)) {
+                                err = 0;
+                                break;
+                        }
+                }
+        }
+
+        mutex_unlock(&pohmelfs_config_lock);
+
+        return err;
+}
+
+int __init pohmelfs_config_init(void)
+{
+        /* XXX remove (void *) cast when vanilla connector got synced */
+        return cn_add_callback(&pohmelfs_cn_id, "pohmelfs", (void *)pohmelfs_cn_callback);
+}
+
+void pohmelfs_config_exit(void)
+{
+        struct pohmelfs_config *c, *tmp;
+        struct pohmelfs_config_group *g, *gtmp;
+
+        cn_del_callback(&pohmelfs_cn_id);
+
+        mutex_lock(&pohmelfs_config_lock);
+        list_for_each_entry_safe(g, gtmp, &pohmelfs_config_list, group_entry) {
+                list_for_each_entry_safe(c, tmp, &g->config_list, config_entry) {
+                        list_del(&c->config_entry);
+                        kfree(c);
+                }
+
+                list_del(&g->group_entry);
+
+                kfree(g->hash_string);
+
+                kfree(g->cipher_string);
+
+                kfree(g);
+        }
+        mutex_unlock(&pohmelfs_config_lock);
+}
diff --git a/drivers/staging/pohmelfs/crypto.c b/drivers/staging/pohmelfs/crypto.c
new file mode 100644
index 00000000000..ad92771dce5
--- /dev/null
+++ b/drivers/staging/pohmelfs/crypto.c
@@ -0,0 +1,878 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/crypto.h>
+#include <linux/highmem.h>
+#include <linux/kthread.h>
+#include <linux/pagemap.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+
+#include "netfs.h"
+
+static struct crypto_hash *pohmelfs_init_hash(struct pohmelfs_sb *psb)
+{
+        int err;
+        struct crypto_hash *hash;
+
+        hash = crypto_alloc_hash(psb->hash_string, 0, CRYPTO_ALG_ASYNC);
+        if (IS_ERR(hash)) {
+                err = PTR_ERR(hash);
+                dprintk("%s: idx: %u: failed to allocate hash '%s', err: %d.\n",
+                                __func__, psb->idx, psb->hash_string, err);
+                goto err_out_exit;
+        }
+
+        psb->crypto_attached_size = crypto_hash_digestsize(hash);
+
+        if (!psb->hash_keysize)
+                return hash;
+
+        err = crypto_hash_setkey(hash, psb->hash_key, psb->hash_keysize);
+        if (err) {
+                dprintk("%s: idx: %u: failed to set key for hash '%s', err: %d.\n",
+                                __func__, psb->idx, psb->hash_string, err);
+                goto err_out_free;
+        }
+
+        return hash;
+
+err_out_free:
+        crypto_free_hash(hash);
+err_out_exit:
+        return ERR_PTR(err);
+}
+
+static struct crypto_ablkcipher *pohmelfs_init_cipher(struct pohmelfs_sb *psb)
+{
+        int err = -EINVAL;
+        struct crypto_ablkcipher *cipher;
+
+        if (!psb->cipher_keysize)
+                goto err_out_exit;
+
+        cipher = crypto_alloc_ablkcipher(psb->cipher_string, 0, 0);
+        if (IS_ERR(cipher)) {
+                err = PTR_ERR(cipher);
+                dprintk("%s: idx: %u: failed to allocate cipher '%s', err: %d.\n",
+                                __func__, psb->idx, psb->cipher_string, err);
+                goto err_out_exit;
+        }
+
+        crypto_ablkcipher_clear_flags(cipher, ~0);
+
+        err = crypto_ablkcipher_setkey(cipher, psb->cipher_key, psb->cipher_keysize);
+        if (err) {
+                dprintk("%s: idx: %u: failed to set key for cipher '%s', err: %d.\n",
+                                __func__, psb->idx, psb->cipher_string, err);
+                goto err_out_free;
+        }
+
+        return cipher;
+
+err_out_free:
+        crypto_free_ablkcipher(cipher);
+err_out_exit:
+        return ERR_PTR(err);
+}
+
+int pohmelfs_crypto_engine_init(struct pohmelfs_crypto_engine *e, struct pohmelfs_sb *psb)
+{
+        int err;
+
+        e->page_num = 0;
+
+        e->size = PAGE_SIZE;
+        e->data = kmalloc(e->size, GFP_KERNEL);
+        if (!e->data) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+
+        if (psb->hash_string) {
+                e->hash = pohmelfs_init_hash(psb);
+                if (IS_ERR(e->hash)) {
+                        err = PTR_ERR(e->hash);
+                        e->hash = NULL;
+                        goto err_out_free;
+                }
+        }
+
+        if (psb->cipher_string) {
+                e->cipher = pohmelfs_init_cipher(psb);
+                if (IS_ERR(e->cipher)) {
+                        err = PTR_ERR(e->cipher);
+                        e->cipher = NULL;
+                        goto err_out_free_hash;
+                }
+        }
+
+        return 0;
+
+err_out_free_hash:
+        crypto_free_hash(e->hash);
+err_out_free:
+        kfree(e->data);
+err_out_exit:
+        return err;
+}
+
+void pohmelfs_crypto_engine_exit(struct pohmelfs_crypto_engine *e)
+{
+        crypto_free_hash(e->hash);
+        crypto_free_ablkcipher(e->cipher);
+        kfree(e->data);
+}
+
+static void pohmelfs_crypto_complete(struct crypto_async_request *req, int err)
+{
+        struct pohmelfs_crypto_completion *c = req->data;
+
+        if (err == -EINPROGRESS)
+                return;
+
+        dprintk("%s: req: %p, err: %d.\n", __func__, req, err);
+        c->error = err;
+        complete(&c->complete);
+}
+
+static int pohmelfs_crypto_process(struct ablkcipher_request *req,
+                struct scatterlist *sg_dst, struct scatterlist *sg_src,
+                void *iv, int enc, unsigned long timeout)
+{
+        struct pohmelfs_crypto_completion complete;
+        int err;
+
+        init_completion(&complete.complete);
+        complete.error = -EINPROGRESS;
+
+        ablkcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+                                        pohmelfs_crypto_complete, &complete);
+
+        ablkcipher_request_set_crypt(req, sg_src, sg_dst, sg_src->length, iv);
+
+        if (enc)
+                err = crypto_ablkcipher_encrypt(req);
+        else
+                err = crypto_ablkcipher_decrypt(req);
+
+        switch (err) {
+        case -EINPROGRESS:
+        case -EBUSY:
+                err = wait_for_completion_interruptible_timeout(&complete.complete,
+                                        timeout);
+                if (!err)
+                        err = -ETIMEDOUT;
+                else if (err > 0)
+                        err = complete.error;
+                break;
+        default:
+                break;
+        }
+
+        return err;
+}
+
+int pohmelfs_crypto_process_input_data(struct pohmelfs_crypto_engine *e, u64 cmd_iv,
+                void *data, struct page *page, unsigned int size)
+{
+        int err;
+        struct scatterlist sg;
+
+        if (!e->cipher && !e->hash)
+                return 0;
+
+        dprintk("%s: eng: %p, iv: %llx, data: %p, page: %p/%lu, size: %u.\n",
+                __func__, e, cmd_iv, data, page, (page) ? page->index : 0, size);
+
+        if (data) {
+                sg_init_one(&sg, data, size);
+        } else {
+                sg_init_table(&sg, 1);
+                sg_set_page(&sg, page, size, 0);
+        }
+
+        if (e->cipher) {
+                struct ablkcipher_request *req = e->data + crypto_hash_digestsize(e->hash);
+                u8 iv[32];
+
+                memset(iv, 0, sizeof(iv));
+                memcpy(iv, &cmd_iv, sizeof(cmd_iv));
+
+                ablkcipher_request_set_tfm(req, e->cipher);
+
+                err = pohmelfs_crypto_process(req, &sg, &sg, iv, 0, e->timeout);
+                if (err)
+                        goto err_out_exit;
+        }
+
+        if (e->hash) {
+                struct hash_desc desc;
+                void *dst = e->data + e->size/2;
+
+                desc.tfm = e->hash;
+                desc.flags = 0;
+
+                err = crypto_hash_init(&desc);
+                if (err)
+                        goto err_out_exit;
+
+                err = crypto_hash_update(&desc, &sg, size);
+                if (err)
+                        goto err_out_exit;
+
+                err = crypto_hash_final(&desc, dst);
+                if (err)
+                        goto err_out_exit;
+
+                err = !!memcmp(dst, e->data, crypto_hash_digestsize(e->hash));
+
+                if (err) {
+#ifdef CONFIG_POHMELFS_DEBUG
+                        unsigned int i;
+                        unsigned char *recv = e->data, *calc = dst;
+
+                        dprintk("%s: eng: %p, hash: %p, cipher: %p: iv : %llx, hash mismatch (recv/calc): ",
+                                        __func__, e, e->hash, e->cipher, cmd_iv);
+                        for (i = 0; i < crypto_hash_digestsize(e->hash); ++i) {
+#if 0
+                                dprintka("%02x ", recv[i]);
+                                if (recv[i] != calc[i]) {
+                                        dprintka("| calc byte: %02x.\n", calc[i]);
+                                        break;
+                                }
+#else
+                                dprintka("%02x/%02x ", recv[i], calc[i]);
+#endif
+                        }
+                        dprintk("\n");
+#endif
+                        goto err_out_exit;
+                } else {
+                        dprintk("%s: eng: %p, hash: %p, cipher: %p: hashes matched.\n",
+                                        __func__, e, e->hash, e->cipher);
+                }
+        }
+
+        dprintk("%s: eng: %p, size: %u, hash: %p, cipher: %p: completed.\n",
+                        __func__, e, e->size, e->hash, e->cipher);
+
+        return 0;
+
+err_out_exit:
+        dprintk("%s: eng: %p, hash: %p, cipher: %p: err: %d.\n",
+                        __func__, e, e->hash, e->cipher, err);
+        return err;
+}
+
+static int pohmelfs_trans_iter(struct netfs_trans *t, struct pohmelfs_crypto_engine *e,
+                int (*iterator) (struct pohmelfs_crypto_engine *e,
+                                  struct scatterlist *dst,
+                                  struct scatterlist *src))
+{
+        void *data = t->iovec.iov_base + sizeof(struct netfs_cmd) + t->psb->crypto_attached_size;
+        unsigned int size = t->iovec.iov_len - sizeof(struct netfs_cmd) - t->psb->crypto_attached_size;
+        struct netfs_cmd *cmd = data;
+        unsigned int sz, pages = t->attached_pages, i, csize, cmd_cmd, dpage_idx;
+        struct scatterlist sg_src, sg_dst;
+        int err;
+
+        while (size) {
+                cmd = data;
+                cmd_cmd = __be16_to_cpu(cmd->cmd);
+                csize = __be32_to_cpu(cmd->size);
+                cmd->iv = __cpu_to_be64(e->iv);
+
+                if (cmd_cmd == NETFS_READ_PAGES || cmd_cmd == NETFS_READ_PAGE)
+                        csize = __be16_to_cpu(cmd->ext);
+
+                sz = csize + __be16_to_cpu(cmd->cpad) + sizeof(struct netfs_cmd);
+
+                dprintk("%s: size: %u, sz: %u, cmd_size: %u, cmd_cpad: %u.\n",
+                                __func__, size, sz, __be32_to_cpu(cmd->size), __be16_to_cpu(cmd->cpad));
+
+                data += sz;
+                size -= sz;
+
+                sg_init_one(&sg_src, cmd->data, sz - sizeof(struct netfs_cmd));
+                sg_init_one(&sg_dst, cmd->data, sz - sizeof(struct netfs_cmd));
+
+                err = iterator(e, &sg_dst, &sg_src);
+                if (err)
+                        return err;
+        }
+
+        if (!pages)
+                return 0;
+
+        dpage_idx = 0;
+        for (i = 0; i < t->page_num; ++i) {
+                struct page *page = t->pages[i];
+                struct page *dpage = e->pages[dpage_idx];
+
+                if (!page)
+                        continue;
+
+                sg_init_table(&sg_src, 1);
+                sg_init_table(&sg_dst, 1);
+                sg_set_page(&sg_src, page, page_private(page), 0);
+                sg_set_page(&sg_dst, dpage, page_private(page), 0);
+
+                err = iterator(e, &sg_dst, &sg_src);
+                if (err)
+                        return err;
+
+                pages--;
+                if (!pages)
+                        break;
+                dpage_idx++;
+        }
+
+        return 0;
+}
+
+static int pohmelfs_encrypt_iterator(struct pohmelfs_crypto_engine *e,
+                struct scatterlist *sg_dst, struct scatterlist *sg_src)
+{
+        struct ablkcipher_request *req = e->data;
+        u8 iv[32];
+
+        memset(iv, 0, sizeof(iv));
+
+        memcpy(iv, &e->iv, sizeof(e->iv));
+
+        return pohmelfs_crypto_process(req, sg_dst, sg_src, iv, 1, e->timeout);
+}
+
+static int pohmelfs_encrypt(struct pohmelfs_crypto_thread *tc)
+{
+        struct netfs_trans *t = tc->trans;
+        struct pohmelfs_crypto_engine *e = &tc->eng;
+        struct ablkcipher_request *req = e->data;
+
+        memset(req, 0, sizeof(struct ablkcipher_request));
+        ablkcipher_request_set_tfm(req, e->cipher);
+
+        e->iv = pohmelfs_gen_iv(t);
+
+        return pohmelfs_trans_iter(t, e, pohmelfs_encrypt_iterator);
+}
+
+static int pohmelfs_hash_iterator(struct pohmelfs_crypto_engine *e,
+                struct scatterlist *sg_dst, struct scatterlist *sg_src)
+{
+        return crypto_hash_update(e->data, sg_src, sg_src->length);
+}
+
+static int pohmelfs_hash(struct pohmelfs_crypto_thread *tc)
+{
+        struct pohmelfs_crypto_engine *e = &tc->eng;
+        struct hash_desc *desc = e->data;
+        unsigned char *dst = tc->trans->iovec.iov_base + sizeof(struct netfs_cmd);
+        int err;
+
+        desc->tfm = e->hash;
+        desc->flags = 0;
+
+        err = crypto_hash_init(desc);
+        if (err)
+                return err;
+
+        err = pohmelfs_trans_iter(tc->trans, e, pohmelfs_hash_iterator);
+        if (err)
+                return err;
+
+        err = crypto_hash_final(desc, dst);
+        if (err)
+                return err;
+
+        {
+                unsigned int i;
+                dprintk("%s: ", __func__);
+                for (i = 0; i < tc->psb->crypto_attached_size; ++i)
+                        dprintka("%02x ", dst[i]);
+                dprintka("\n");
+        }
+
+        return 0;
+}
+
+static void pohmelfs_crypto_pages_free(struct pohmelfs_crypto_engine *e)
+{
+        unsigned int i;
+
+        for (i = 0; i < e->page_num; ++i)
+                __free_page(e->pages[i]);
+        kfree(e->pages);
+}
+
+static int pohmelfs_crypto_pages_alloc(struct pohmelfs_crypto_engine *e, struct pohmelfs_sb *psb)
+{
+        unsigned int i;
+
+        e->pages = kmalloc(psb->trans_max_pages * sizeof(struct page *), GFP_KERNEL);
+        if (!e->pages)
+                return -ENOMEM;
+
+        for (i = 0; i < psb->trans_max_pages; ++i) {
+                e->pages[i] = alloc_page(GFP_KERNEL);
+                if (!e->pages[i])
+                        break;
+        }
+
+        e->page_num = i;
+        if (!e->page_num)
+                goto err_out_free;
+
+        return 0;
+
+err_out_free:
+        kfree(e->pages);
+        return -ENOMEM;
+}
+
+static void pohmelfs_sys_crypto_exit_one(struct pohmelfs_crypto_thread *t)
+{
+        struct pohmelfs_sb *psb = t->psb;
+
+        if (t->thread)
+                kthread_stop(t->thread);
+
+        mutex_lock(&psb->crypto_thread_lock);
+        list_del(&t->thread_entry);
+        psb->crypto_thread_num--;
+        mutex_unlock(&psb->crypto_thread_lock);
+
+        pohmelfs_crypto_engine_exit(&t->eng);
+        pohmelfs_crypto_pages_free(&t->eng);
+        kfree(t);
+}
+
+static int pohmelfs_crypto_finish(struct netfs_trans *t, struct pohmelfs_sb *psb, int err)
+{
+        struct netfs_cmd *cmd = t->iovec.iov_base;
+        netfs_convert_cmd(cmd);
+
+        if (likely(!err))
+                err = netfs_trans_finish_send(t, psb);
+
+        t->result = err;
+        netfs_trans_put(t);
+
+        return err;
+}
+
+void pohmelfs_crypto_thread_make_ready(struct pohmelfs_crypto_thread *th)
+{
+        struct pohmelfs_sb *psb = th->psb;
+
+        th->page = NULL;
+        th->trans = NULL;
+
+        mutex_lock(&psb->crypto_thread_lock);
+        list_move_tail(&th->thread_entry, &psb->crypto_ready_list);
+        mutex_unlock(&psb->crypto_thread_lock);
+        wake_up(&psb->wait);
+}
+
+static int pohmelfs_crypto_thread_trans(struct pohmelfs_crypto_thread *t)
+{
+        struct netfs_trans *trans;
+        int err = 0;
+
+        trans = t->trans;
+        trans->eng = NULL;
+
+        if (t->eng.hash) {
+                err = pohmelfs_hash(t);
+                if (err)
+                        goto out_complete;
+        }
+
+        if (t->eng.cipher) {
+                err = pohmelfs_encrypt(t);
+                if (err)
+                        goto out_complete;
+                trans->eng = &t->eng;
+        }
+
+out_complete:
+        t->page = NULL;
+        t->trans = NULL;
+
+        if (!trans->eng)
+                pohmelfs_crypto_thread_make_ready(t);
+
+        pohmelfs_crypto_finish(trans, t->psb, err);
+        return err;
+}
+
+static int pohmelfs_crypto_thread_page(struct pohmelfs_crypto_thread *t)
+{
+        struct pohmelfs_crypto_engine *e = &t->eng;
+        struct page *page = t->page;
+        int err;
+
+        WARN_ON(!PageChecked(page));
+
+        err = pohmelfs_crypto_process_input_data(e, e->iv, NULL, page, t->size);
+        if (!err)
+                SetPageUptodate(page);
+        else
+                SetPageError(page);
+        unlock_page(page);
+        page_cache_release(page);
+
+        pohmelfs_crypto_thread_make_ready(t);
+
+        return err;
+}
+
+static int pohmelfs_crypto_thread_func(void *data)
+{
+        struct pohmelfs_crypto_thread *t = data;
+
+        while (!kthread_should_stop()) {
+                wait_event_interruptible(t->wait, kthread_should_stop() ||
+                                t->trans || t->page);
+
+                if (kthread_should_stop())
+                        break;
+
+                if (!t->trans && !t->page)
+                        continue;
+
+                dprintk("%s: thread: %p, trans: %p, page: %p.\n",
+                                __func__, t, t->trans, t->page);
+
+                if (t->trans)
+                        pohmelfs_crypto_thread_trans(t);
+                else if (t->page)
+                        pohmelfs_crypto_thread_page(t);
+        }
+
+        return 0;
+}
+
+static void pohmelfs_crypto_flush(struct pohmelfs_sb *psb, struct list_head *head)
+{
+        while (!list_empty(head)) {
+                struct pohmelfs_crypto_thread *t = NULL;
+
+                mutex_lock(&psb->crypto_thread_lock);
+                if (!list_empty(head)) {
+                        t = list_first_entry(head, struct pohmelfs_crypto_thread, thread_entry);
+                        list_del_init(&t->thread_entry);
+                }
+                mutex_unlock(&psb->crypto_thread_lock);
+
+                if (t)
+                        pohmelfs_sys_crypto_exit_one(t);
+        }
+}
+
+static void pohmelfs_sys_crypto_exit(struct pohmelfs_sb *psb)
+{
+        while (!list_empty(&psb->crypto_active_list) || !list_empty(&psb->crypto_ready_list)) {
+                dprintk("%s: crypto_thread_num: %u.\n", __func__, psb->crypto_thread_num);
+                pohmelfs_crypto_flush(psb, &psb->crypto_active_list);
+                pohmelfs_crypto_flush(psb, &psb->crypto_ready_list);
+        }
+}
+
+static int pohmelfs_sys_crypto_init(struct pohmelfs_sb *psb)
+{
+        unsigned int i;
+        struct pohmelfs_crypto_thread *t;
+        struct pohmelfs_config *c;
+        struct netfs_state *st;
+        int err;
+
+        list_for_each_entry(c, &psb->state_list, config_entry) {
+                st = &c->state;
+
+                err = pohmelfs_crypto_engine_init(&st->eng, psb);
+                if (err)
+                        goto err_out_exit;
+
+                dprintk("%s: st: %p, eng: %p, hash: %p, cipher: %p.\n",
+                                __func__, st, &st->eng, &st->eng.hash, &st->eng.cipher);
+        }
+
+        for (i = 0; i < psb->crypto_thread_num; ++i) {
+                err = -ENOMEM;
+                t = kzalloc(sizeof(struct pohmelfs_crypto_thread), GFP_KERNEL);
+                if (!t)
+                        goto err_out_free_state_engines;
+
+                init_waitqueue_head(&t->wait);
+
+                t->psb = psb;
+                t->trans = NULL;
+                t->eng.thread = t;
+
+                err = pohmelfs_crypto_engine_init(&t->eng, psb);
+                if (err)
+                        goto err_out_free_state_engines;
+
+                err = pohmelfs_crypto_pages_alloc(&t->eng, psb);
+                if (err)
+                        goto err_out_free;
+
+                t->thread = kthread_run(pohmelfs_crypto_thread_func, t,
+                                "pohmelfs-crypto-%d-%d", psb->idx, i);
+                if (IS_ERR(t->thread)) {
+                        err = PTR_ERR(t->thread);
+                        t->thread = NULL;
+                        goto err_out_free;
+                }
+
+                if (t->eng.cipher)
+                        psb->crypto_align_size = crypto_ablkcipher_blocksize(t->eng.cipher);
+
+                mutex_lock(&psb->crypto_thread_lock);
+                list_add_tail(&t->thread_entry, &psb->crypto_ready_list);
+                mutex_unlock(&psb->crypto_thread_lock);
+        }
+
+        psb->crypto_thread_num = i;
+        return 0;
+
+err_out_free:
+        pohmelfs_sys_crypto_exit_one(t);
+err_out_free_state_engines:
+        list_for_each_entry(c, &psb->state_list, config_entry) {
+                st = &c->state;
+                pohmelfs_crypto_engine_exit(&st->eng);
+        }
+err_out_exit:
+        pohmelfs_sys_crypto_exit(psb);
+        return err;
+}
+
+void pohmelfs_crypto_exit(struct pohmelfs_sb *psb)
+{
+        pohmelfs_sys_crypto_exit(psb);
+
+        kfree(psb->hash_string);
+        kfree(psb->cipher_string);
+}
+
+static int pohmelfs_crypt_init_complete(struct page **pages, unsigned int page_num,
+                void *private, int err)
+{
+        struct pohmelfs_sb *psb = private;
+
+        psb->flags = -err;
+        dprintk("%s: err: %d.\n", __func__, err);
+
+        wake_up(&psb->wait);
+
+        return err;
+}
+
+static int pohmelfs_crypto_init_handshake(struct pohmelfs_sb *psb)
+{
+        struct netfs_trans *t;
+        struct netfs_crypto_capabilities *cap;
+        struct netfs_cmd *cmd;
+        char *str;
+        int err = -ENOMEM, size;
+
+        size = sizeof(struct netfs_crypto_capabilities) +
+                psb->cipher_strlen + psb->hash_strlen + 2; /* 0 bytes */
+
+        t = netfs_trans_alloc(psb, size, 0, 0);
+        if (!t)
+                goto err_out_exit;
+
+        t->complete = pohmelfs_crypt_init_complete;
+        t->private = psb;
+
+        cmd = netfs_trans_current(t);
+        cap = (struct netfs_crypto_capabilities *)(cmd + 1);
+        str = (char *)(cap + 1);
+
+        cmd->cmd = NETFS_CAPABILITIES;
+        cmd->id = POHMELFS_CRYPTO_CAPABILITIES;
+        cmd->size = size;
+        cmd->start = 0;
+        cmd->ext = 0;
+        cmd->csize = 0;
+
+        netfs_convert_cmd(cmd);
+        netfs_trans_update(cmd, t, size);
+
+        cap->hash_strlen = psb->hash_strlen;
+        if (cap->hash_strlen) {
+                sprintf(str, "%s", psb->hash_string);
+                str += cap->hash_strlen;
+        }
+
+        cap->cipher_strlen = psb->cipher_strlen;
+        cap->cipher_keysize = psb->cipher_keysize;
+        if (cap->cipher_strlen)
+                sprintf(str, "%s", psb->cipher_string);
+
+        netfs_convert_crypto_capabilities(cap);
+
+        psb->flags = ~0;
+        err = netfs_trans_finish(t, psb);
+        if (err)
+                goto err_out_exit;
+
+        err = wait_event_interruptible_timeout(psb->wait, (psb->flags != ~0),
+                        psb->wait_on_page_timeout);
+        if (!err)
+                err = -ETIMEDOUT;
+        else if (err > 0)
+                err = -psb->flags;
+
+        if (!err)
+                psb->perform_crypto = 1;
+        psb->flags = 0;
+
+        /*
+         * At this point NETFS_CAPABILITIES response command
+         * should setup superblock in a way, which is acceptable
+         * for both client and server, so if server refuses connection,
+         * it will send error in transaction response.
+         */
+
+        if (err)
+                goto err_out_exit;
+
+        return 0;
+
+err_out_exit:
+        return err;
+}
+
+int pohmelfs_crypto_init(struct pohmelfs_sb *psb)
+{
+        int err;
+
+        if (!psb->cipher_string && !psb->hash_string)
+                return 0;
+
+        err = pohmelfs_crypto_init_handshake(psb);
+        if (err)
+                return err;
+
+        err = pohmelfs_sys_crypto_init(psb);
+        if (err)
+                return err;
+
+        return 0;
+}
+
+static int pohmelfs_crypto_thread_get(struct pohmelfs_sb *psb,
+                int (*action)(struct pohmelfs_crypto_thread *t, void *data), void *data)
+{
+        struct pohmelfs_crypto_thread *t = NULL;
+        int err;
+
+        while (!t) {
+                err = wait_event_interruptible_timeout(psb->wait,
+                                !list_empty(&psb->crypto_ready_list),
+                                psb->wait_on_page_timeout);
+
+                t = NULL;
+                err = 0;
+                mutex_lock(&psb->crypto_thread_lock);
+                if (!list_empty(&psb->crypto_ready_list)) {
+                        t = list_entry(psb->crypto_ready_list.prev,
+                                        struct pohmelfs_crypto_thread,
+                                        thread_entry);
+
+                        list_move_tail(&t->thread_entry,
+                                        &psb->crypto_active_list);
+
+                        action(t, data);
+                        wake_up(&t->wait);
+
+                }
+                mutex_unlock(&psb->crypto_thread_lock);
+        }
+
+        return err;
+}
+
+static int pohmelfs_trans_crypt_action(struct pohmelfs_crypto_thread *t, void *data)
+{
+        struct netfs_trans *trans = data;
+
+        netfs_trans_get(trans);
+        t->trans = trans;
+
+        dprintk("%s: t: %p, gen: %u, thread: %p.\n", __func__, trans, trans->gen, t);
+        return 0;
+}
+
+int pohmelfs_trans_crypt(struct netfs_trans *trans, struct pohmelfs_sb *psb)
+{
+        if ((!psb->hash_string && !psb->cipher_string) || !psb->perform_crypto) {
+                netfs_trans_get(trans);
+                return pohmelfs_crypto_finish(trans, psb, 0);
+        }
+
+        return pohmelfs_crypto_thread_get(psb, pohmelfs_trans_crypt_action, trans);
+}
+
+struct pohmelfs_crypto_input_action_data {
+        struct page                     *page;
+        struct pohmelfs_crypto_engine   *e;
+        u64                             iv;
+        unsigned int                    size;
+};
+
+static int pohmelfs_crypt_input_page_action(struct pohmelfs_crypto_thread *t, void *data)
+{
+        struct pohmelfs_crypto_input_action_data *act = data;
+
+        memcpy(t->eng.data, act->e->data, t->psb->crypto_attached_size);
+
+        t->size = act->size;
+        t->eng.iv = act->iv;
+
+        t->page = act->page;
+        return 0;
+}
+
+int pohmelfs_crypto_process_input_page(struct pohmelfs_crypto_engine *e,
+                struct page *page, unsigned int size, u64 iv)
+{
+        struct inode *inode = page->mapping->host;
+        struct pohmelfs_crypto_input_action_data act;
+        int err = -ENOENT;
+
+        act.page = page;
+        act.e = e;
+        act.size = size;
+        act.iv = iv;
+
+        err = pohmelfs_crypto_thread_get(POHMELFS_SB(inode->i_sb),
+                        pohmelfs_crypt_input_page_action, &act);
+        if (err)
+                goto err_out_exit;
+
+        return 0;
+
+err_out_exit:
+        SetPageUptodate(page);
+        page_cache_release(page);
+
+        return err;
+}
diff --git a/drivers/staging/pohmelfs/dir.c b/drivers/staging/pohmelfs/dir.c
new file mode 100644
index 00000000000..7598e77672a
--- /dev/null
+++ b/drivers/staging/pohmelfs/dir.c
@@ -0,0 +1,1101 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/jhash.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+
+#include "netfs.h"
+
+static int pohmelfs_cmp_hash(struct pohmelfs_name *n, u32 hash)
+{
+        if (n->hash > hash)
+                return -1;
+        if (n->hash < hash)
+                return 1;
+
+        return 0;
+}
+
+static struct pohmelfs_name *pohmelfs_search_hash_unprecise(struct pohmelfs_inode *pi, u32 hash)
+{
+        struct rb_node *n = pi->hash_root.rb_node;
+        struct pohmelfs_name *tmp = NULL;
+        int cmp;
+
+        while (n) {
+                tmp = rb_entry(n, struct pohmelfs_name, hash_node);
+
+                cmp = pohmelfs_cmp_hash(tmp, hash);
+                if (cmp < 0)
+                        n = n->rb_left;
+                else if (cmp > 0)
+                        n = n->rb_right;
+                else
+                        break;
+
+        }
+
+        return tmp;
+}
+
+struct pohmelfs_name *pohmelfs_search_hash(struct pohmelfs_inode *pi, u32 hash)
+{
+        struct pohmelfs_name *tmp;
+
+        tmp = pohmelfs_search_hash_unprecise(pi, hash);
+        if (tmp && (tmp->hash == hash))
+                return tmp;
+
+        return NULL;
+}
+
+static void __pohmelfs_name_del(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
+{
+        rb_erase(&node->hash_node, &parent->hash_root);
+}
+
+/*
+ * Remove name cache entry from its caches and free it.
+ */
+static void pohmelfs_name_free(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
+{
+        __pohmelfs_name_del(parent, node);
+        list_del(&node->sync_create_entry);
+        kfree(node);
+}
+
+static struct pohmelfs_name *pohmelfs_insert_hash(struct pohmelfs_inode *pi,
+                struct pohmelfs_name *new)
+{
+        struct rb_node **n = &pi->hash_root.rb_node, *parent = NULL;
+        struct pohmelfs_name *ret = NULL, *tmp;
+        int cmp;
+
+        while (*n) {
+                parent = *n;
+
+                tmp = rb_entry(parent, struct pohmelfs_name, hash_node);
+
+                cmp = pohmelfs_cmp_hash(tmp, new->hash);
+                if (cmp < 0)
+                        n = &parent->rb_left;
+                else if (cmp > 0)
+                        n = &parent->rb_right;
+                else {
+                        ret = tmp;
+                        break;
+                }
+        }
+
+        if (ret) {
+                printk("%s: exist: parent: %llu, ino: %llu, hash: %x, len: %u, data: '%s', "
+                                        "new: ino: %llu, hash: %x, len: %u, data: '%s'.\n",
+                                __func__, pi->ino,
+                                ret->ino, ret->hash, ret->len, ret->data,
+                                new->ino, new->hash, new->len, new->data);
+                ret->ino = new->ino;
+                return ret;
+        }
+
+        rb_link_node(&new->hash_node, parent, n);
+        rb_insert_color(&new->hash_node, &pi->hash_root);
+
+        return NULL;
+}
+
+/*
+ * Free name cache for given inode.
+ */
+void pohmelfs_free_names(struct pohmelfs_inode *parent)
+{
+        struct rb_node *rb_node;
+        struct pohmelfs_name *n;
+
+        for (rb_node = rb_first(&parent->hash_root); rb_node;) {
+                n = rb_entry(rb_node, struct pohmelfs_name, hash_node);
+                rb_node = rb_next(rb_node);
+
+                pohmelfs_name_free(parent, n);
+        }
+}
+
+static void pohmelfs_fix_offset(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
+{
+        parent->total_len -= node->len;
+}
+
+/*
+ * Free name cache entry helper.
+ */
+void pohmelfs_name_del(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
+{
+        pohmelfs_fix_offset(parent, node);
+        pohmelfs_name_free(parent, node);
+}
+
+/*
+ * Insert new name cache entry into all hash cache.
+ */
+static int pohmelfs_insert_name(struct pohmelfs_inode *parent, struct pohmelfs_name *n)
+{
+        struct pohmelfs_name *name;
+
+        name = pohmelfs_insert_hash(parent, n);
+        if (name)
+                return -EEXIST;
+
+        parent->total_len += n->len;
+        list_add_tail(&n->sync_create_entry, &parent->sync_create_list);
+
+        return 0;
+}
+
+/*
+ * Allocate new name cache entry.
+ */
+static struct pohmelfs_name *pohmelfs_name_alloc(unsigned int len)
+{
+        struct pohmelfs_name *n;
+
+        n = kzalloc(sizeof(struct pohmelfs_name) + len, GFP_KERNEL);
+        if (!n)
+                return NULL;
+
+        INIT_LIST_HEAD(&n->sync_create_entry);
+
+        n->data = (char *)(n+1);
+
+        return n;
+}
+
+/*
+ * Add new name entry into directory's cache.
+ */
+static int pohmelfs_add_dir(struct pohmelfs_sb *psb, struct pohmelfs_inode *parent,
+                struct pohmelfs_inode *npi, struct qstr *str, unsigned int mode, int link)
+{
+        int err = -ENOMEM;
+        struct pohmelfs_name *n;
+
+        n = pohmelfs_name_alloc(str->len + 1);
+        if (!n)
+                goto err_out_exit;
+
+        n->ino = npi->ino;
+        n->mode = mode;
+        n->len = str->len;
+        n->hash = str->hash;
+        sprintf(n->data, "%s", str->name);
+
+        mutex_lock(&parent->offset_lock);
+        err = pohmelfs_insert_name(parent, n);
+        mutex_unlock(&parent->offset_lock);
+
+        if (err) {
+                if (err != -EEXIST)
+                        goto err_out_free;
+                kfree(n);
+        }
+
+        return 0;
+
+err_out_free:
+        kfree(n);
+err_out_exit:
+        return err;
+}
+
+/*
+ * Create new inode for given parameters (name, inode info, parent).
+ * This does not create object on the server, it will be synced there during writeback.
+ */
+struct pohmelfs_inode *pohmelfs_new_inode(struct pohmelfs_sb *psb,
+                struct pohmelfs_inode *parent, struct qstr *str,
+                struct netfs_inode_info *info, int link)
+{
+        struct inode *new = NULL;
+        struct pohmelfs_inode *npi;
+        int err = -EEXIST;
+
+        dprintk("%s: creating inode: parent: %llu, ino: %llu, str: %p.\n",
+                        __func__, (parent) ? parent->ino : 0, info->ino, str);
+
+        err = -ENOMEM;
+        new = iget_locked(psb->sb, info->ino);
+        if (!new)
+                goto err_out_exit;
+
+        npi = POHMELFS_I(new);
+        npi->ino = info->ino;
+        err = 0;
+
+        if (new->i_state & I_NEW) {
+                dprintk("%s: filling VFS inode: %lu/%llu.\n",
+                                __func__, new->i_ino, info->ino);
+                pohmelfs_fill_inode(new, info);
+
+                if (S_ISDIR(info->mode)) {
+                        struct qstr s;
+
+                        s.name = ".";
+                        s.len = 1;
+                        s.hash = jhash(s.name, s.len, 0);
+
+                        err = pohmelfs_add_dir(psb, npi, npi, &s, info->mode, 0);
+                        if (err)
+                                goto err_out_put;
+
+                        s.name = "..";
+                        s.len = 2;
+                        s.hash = jhash(s.name, s.len, 0);
+
+                        err = pohmelfs_add_dir(psb, npi, (parent) ? parent : npi, &s,
+                                        (parent) ? parent->vfs_inode.i_mode : npi->vfs_inode.i_mode, 0);
+                        if (err)
+                                goto err_out_put;
+                }
+        }
+
+        if (str) {
+                if (parent) {
+                        err = pohmelfs_add_dir(psb, parent, npi, str, info->mode, link);
+
+                        dprintk("%s: %s inserted name: '%s', new_offset: %llu, ino: %llu, parent: %llu.\n",
+                                        __func__, (err) ? "unsuccessfully" : "successfully",
+                                        str->name, parent->total_len, info->ino, parent->ino);
+
+                        if (err && err != -EEXIST)
+                                goto err_out_put;
+                }
+        }
+
+        if (new->i_state & I_NEW) {
+                if (parent)
+                        mark_inode_dirty(&parent->vfs_inode);
+                mark_inode_dirty(new);
+        }
+
+        set_bit(NETFS_INODE_OWNED, &npi->state);
+        npi->lock_type = POHMELFS_WRITE_LOCK;
+        unlock_new_inode(new);
+
+        return npi;
+
+err_out_put:
+        printk("%s: putting inode: %p, npi: %p, error: %d.\n", __func__, new, npi, err);
+        iput(new);
+err_out_exit:
+        return ERR_PTR(err);
+}
+
+static int pohmelfs_remote_sync_complete(struct page **pages, unsigned int page_num,
+                void *private, int err)
+{
+        struct pohmelfs_inode *pi = private;
+        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
+
+        dprintk("%s: ino: %llu, err: %d.\n", __func__, pi->ino, err);
+
+        if (err)
+                pi->error = err;
+        wake_up(&psb->wait);
+        pohmelfs_put_inode(pi);
+
+        return err;
+}
+
+/*
+ * Receive directory content from the server.
+ * This should be only done for objects, which were not created locally,
+ * and which were not synced previously.
+ */
+static int pohmelfs_sync_remote_dir(struct pohmelfs_inode *pi)
+{
+        struct inode *inode = &pi->vfs_inode;
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        long ret = psb->wait_on_page_timeout;
+        int err;
+
+        dprintk("%s: dir: %llu, state: %lx: remote_synced: %d.\n",
+                __func__, pi->ino, pi->state, test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state));
+
+        if (test_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &pi->state))
+                return 0;
+
+        if (!igrab(inode)) {
+                err = -ENOENT;
+                goto err_out_exit;
+        }
+
+        err = pohmelfs_meta_command(pi, NETFS_READDIR, NETFS_TRANS_SINGLE_DST,
+                        pohmelfs_remote_sync_complete, pi, 0);
+        if (err)
+                goto err_out_exit;
+
+        pi->error = 0;
+        ret = wait_event_interruptible_timeout(psb->wait,
+                        test_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &pi->state) || pi->error, ret);
+        dprintk("%s: awake dir: %llu, ret: %ld, err: %d.\n", __func__, pi->ino, ret, pi->error);
+        if (ret <= 0) {
+                err = ret;
+                if (!err)
+                        err = -ETIMEDOUT;
+                goto err_out_exit;
+        }
+
+        if (pi->error)
+                return pi->error;
+
+        return 0;
+
+err_out_exit:
+        clear_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);
+
+        return err;
+}
+
+static int pohmelfs_dir_open(struct inode *inode, struct file *file)
+{
+        file->private_data = NULL;
+        return 0;
+}
+
+/*
+ * VFS readdir callback. Syncs directory content from server if needed,
+ * and provides direntry info to the userspace.
+ */
+static int pohmelfs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+        struct inode *inode = file->f_path.dentry->d_inode;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        struct pohmelfs_name *n;
+        struct rb_node *rb_node;
+        int err = 0, mode;
+        u64 len;
+
+        dprintk("%s: parent: %llu, fpos: %llu, hash: %08lx.\n",
+                        __func__, pi->ino, (u64)file->f_pos,
+                        (unsigned long)file->private_data);
+#if 0
+        err = pohmelfs_data_lock(pi, 0, ~0, POHMELFS_READ_LOCK);
+        if (err)
+                return err;
+#endif
+        err = pohmelfs_sync_remote_dir(pi);
+        if (err)
+                return err;
+
+        if (file->private_data && (file->private_data == (void *)(unsigned long)file->f_pos))
+                return 0;
+
+        mutex_lock(&pi->offset_lock);
+        n = pohmelfs_search_hash_unprecise(pi, (unsigned long)file->private_data);
+
+        while (n) {
+                mode = (n->mode >> 12) & 15;
+
+                dprintk("%s: offset: %llu, parent ino: %llu, name: '%s', len: %u, ino: %llu, "
+                                "mode: %o/%o, fpos: %llu, hash: %08x.\n",
+                                __func__, file->f_pos, pi->ino, n->data, n->len,
+                                n->ino, n->mode, mode, file->f_pos, n->hash);
+
+                file->private_data = (void *)(unsigned long)n->hash;
+
+                len = n->len;
+                err = filldir(dirent, n->data, n->len, file->f_pos, n->ino, mode);
+
+                if (err < 0) {
+                        dprintk("%s: err: %d.\n", __func__, err);
+                        err = 0;
+                        break;
+                }
+
+                file->f_pos += len;
+
+                rb_node = rb_next(&n->hash_node);
+
+                if (!rb_node || (rb_node == &n->hash_node)) {
+                        file->private_data = (void *)(unsigned long)file->f_pos;
+                        break;
+                }
+
+                n = rb_entry(rb_node, struct pohmelfs_name, hash_node);
+        }
+        mutex_unlock(&pi->offset_lock);
+
+        return err;
+}
+
+static loff_t pohmelfs_dir_lseek(struct file *file, loff_t offset, int origin)
+{
+        file->f_pos = offset;
+        file->private_data = NULL;
+        return offset;
+}
+
+const struct file_operations pohmelfs_dir_fops = {
+        .open = pohmelfs_dir_open,
+        .read = generic_read_dir,
+        .llseek = pohmelfs_dir_lseek,
+        .readdir = pohmelfs_readdir,
+};
+
+/*
+ * Lookup single object on server.
+ */
+static int pohmelfs_lookup_single(struct pohmelfs_inode *parent,
+                struct qstr *str, u64 ino)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(parent->vfs_inode.i_sb);
+        long ret = msecs_to_jiffies(5000);
+        int err;
+
+        set_bit(NETFS_COMMAND_PENDING, &parent->state);
+        err = pohmelfs_meta_command_data(parent, parent->ino, NETFS_LOOKUP,
+                        (char *)str->name, NETFS_TRANS_SINGLE_DST, NULL, NULL, ino);
+        if (err)
+                goto err_out_exit;
+
+        err = 0;
+        ret = wait_event_interruptible_timeout(psb->wait,
+                        !test_bit(NETFS_COMMAND_PENDING, &parent->state), ret);
+        if (ret <= 0) {
+                err = ret;
+                if (!err)
+                        err = -ETIMEDOUT;
+        }
+
+        if (err)
+                goto err_out_exit;
+
+        return 0;
+
+err_out_exit:
+        clear_bit(NETFS_COMMAND_PENDING, &parent->state);
+
+        printk("%s: failed: parent: %llu, ino: %llu, name: '%s', err: %d.\n",
+                        __func__, parent->ino, ino, str->name, err);
+
+        return err;
+}
+
+/*
+ * VFS lookup callback.
+ * We first try to get inode number from local name cache, if we have one,
+ * then inode can be found in inode cache. If there is no inode or no object in
+ * local cache, try to lookup it on server. This only should be done for directories,
+ * which were not created locally, otherwise remote server does not know about dir at all,
+ * so no need to try to know that.
+ */
+struct dentry *pohmelfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
+{
+        struct pohmelfs_inode *parent = POHMELFS_I(dir);
+        struct pohmelfs_name *n;
+        struct inode *inode = NULL;
+        unsigned long ino = 0;
+        int err, lock_type = POHMELFS_READ_LOCK, need_lock = 1;
+        struct qstr str = dentry->d_name;
+
+        if ((nd->intent.open.flags & O_ACCMODE) != O_RDONLY)
+                lock_type = POHMELFS_WRITE_LOCK;
+
+        if (test_bit(NETFS_INODE_OWNED, &parent->state)) {
+                if (lock_type == parent->lock_type)
+                        need_lock = 0;
+                if ((lock_type == POHMELFS_READ_LOCK) && (parent->lock_type == POHMELFS_WRITE_LOCK))
+                        need_lock = 0;
+        }
+
+        if ((lock_type == POHMELFS_READ_LOCK) && !test_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &parent->state))
+                need_lock = 1;
+
+        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);
+
+        mutex_lock(&parent->offset_lock);
+        n = pohmelfs_search_hash(parent, str.hash);
+        if (n)
+                ino = n->ino;
+        mutex_unlock(&parent->offset_lock);
+
+        dprintk("%s: start ino: %lu, inode: %p, name: '%s', hash: %x, parent_state: %lx, need_lock: %d.\n",
+                        __func__, ino, inode, str.name, str.hash, parent->state, need_lock);
+
+        if (ino) {
+                inode = ilookup(dir->i_sb, ino);
+                if (inode)
+                        goto out;
+        }
+
+        dprintk("%s: no inode dir: %p, dir_ino: %llu, name: '%s', len: %u, dir_state: %lx, ino: %lu.\n",
+                        __func__, dir, parent->ino,
+                        str.name, str.len, parent->state, ino);
+
+        if (!ino) {
+                if (!need_lock)
+                        goto out;
+        }
+
+        err = pohmelfs_data_lock(parent, 0, ~0, lock_type);
+        if (err)
+                goto out;
+
+        err = pohmelfs_lookup_single(parent, &str, ino);
+        if (err)
+                goto out;
+
+        if (!ino) {
+                mutex_lock(&parent->offset_lock);
+                n = pohmelfs_search_hash(parent, str.hash);
+                if (n)
+                        ino = n->ino;
+                mutex_unlock(&parent->offset_lock);
+        }
+
+        if (ino) {
+                inode = ilookup(dir->i_sb, ino);
+                dprintk("%s: second lookup ino: %lu, inode: %p, name: '%s', hash: %x.\n",
+                                __func__, ino, inode, str.name, str.hash);
+                if (!inode) {
+                        dprintk("%s: No inode for ino: %lu, name: '%s', hash: %x.\n",
+                                __func__, ino, str.name, str.hash);
+                        /* return NULL; */
+                        return ERR_PTR(-EACCES);
+                }
+        } else {
+                printk("%s: No inode number : name: '%s', hash: %x.\n",
+                        __func__, str.name, str.hash);
+        }
+out:
+        return d_splice_alias(inode, dentry);
+}
+
+/*
+ * Create new object in local cache. Object will be synced to server
+ * during writeback for given inode.
+ */
+struct pohmelfs_inode *pohmelfs_create_entry_local(struct pohmelfs_sb *psb,
+        struct pohmelfs_inode *parent, struct qstr *str, u64 start, int mode)
+{
+        struct pohmelfs_inode *npi;
+        int err = -ENOMEM;
+        struct netfs_inode_info info;
+
+        dprintk("%s: name: '%s', mode: %o, start: %llu.\n",
+                        __func__, str->name, mode, start);
+
+        info.mode = mode;
+        info.ino = start;
+
+        if (!start)
+                info.ino = pohmelfs_new_ino(psb);
+
+        info.nlink = S_ISDIR(mode) ? 2 : 1;
+        info.uid = current_fsuid();
+        info.gid = current_fsgid();
+        info.size = 0;
+        info.blocksize = 512;
+        info.blocks = 0;
+        info.rdev = 0;
+        info.version = 0;
+
+        npi = pohmelfs_new_inode(psb, parent, str, &info, !!start);
+        if (IS_ERR(npi)) {
+                err = PTR_ERR(npi);
+                goto err_out_unlock;
+        }
+
+        return npi;
+
+err_out_unlock:
+        dprintk("%s: err: %d.\n", __func__, err);
+        return ERR_PTR(err);
+}
+
+/*
+ * Create local object and bind it to dentry.
+ */
+static int pohmelfs_create_entry(struct inode *dir, struct dentry *dentry, u64 start, int mode)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(dir->i_sb);
+        struct pohmelfs_inode *npi, *parent;
+        struct qstr str = dentry->d_name;
+        int err;
+
+        parent = POHMELFS_I(dir);
+
+        err = pohmelfs_data_lock(parent, 0, ~0, POHMELFS_WRITE_LOCK);
+        if (err)
+                return err;
+
+        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);
+
+        npi = pohmelfs_create_entry_local(psb, parent, &str, start, mode);
+        if (IS_ERR(npi))
+                return PTR_ERR(npi);
+
+        d_instantiate(dentry, &npi->vfs_inode);
+
+        dprintk("%s: parent: %llu, inode: %llu, name: '%s', parent_nlink: %d, nlink: %d.\n",
+                        __func__, parent->ino, npi->ino, dentry->d_name.name,
+                        (signed)dir->i_nlink, (signed)npi->vfs_inode.i_nlink);
+
+        return 0;
+}
+
+/*
+ * VFS create and mkdir callbacks.
+ */
+static int pohmelfs_create(struct inode *dir, struct dentry *dentry, int mode,
+                struct nameidata *nd)
+{
+        return pohmelfs_create_entry(dir, dentry, 0, mode);
+}
+
+static int pohmelfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+        int err;
+
+        inode_inc_link_count(dir);
+        err = pohmelfs_create_entry(dir, dentry, 0, mode | S_IFDIR);
+        if (err)
+                inode_dec_link_count(dir);
+
+        return err;
+}
+
+static int pohmelfs_remove_entry(struct inode *dir, struct dentry *dentry)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(dir->i_sb);
+        struct inode *inode = dentry->d_inode;
+        struct pohmelfs_inode *parent = POHMELFS_I(dir), *pi = POHMELFS_I(inode);
+        struct pohmelfs_name *n;
+        int err = -ENOENT;
+        struct qstr str = dentry->d_name;
+
+        err = pohmelfs_data_lock(parent, 0, ~0, POHMELFS_WRITE_LOCK);
+        if (err)
+                return err;
+
+        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);
+
+        dprintk("%s: dir_ino: %llu, inode: %llu, name: '%s', nlink: %d.\n",
+                        __func__, parent->ino, pi->ino,
+                        str.name, (signed)inode->i_nlink);
+
+        BUG_ON(!inode);
+
+        mutex_lock(&parent->offset_lock);
+        n = pohmelfs_search_hash(parent, str.hash);
+        if (n) {
+                pohmelfs_fix_offset(parent, n);
+                if (test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state))
+                        pohmelfs_remove_child(pi, n);
+
+                pohmelfs_name_free(parent, n);
+                err = 0;
+        }
+        mutex_unlock(&parent->offset_lock);
+
+        if (!err) {
+                psb->avail_size += inode->i_size;
+
+                pohmelfs_inode_del_inode(psb, pi);
+
+                mark_inode_dirty(dir);
+
+                inode->i_ctime = dir->i_ctime;
+                if (inode->i_nlink)
+                        inode_dec_link_count(inode);
+        }
+
+        return err;
+}
+
+/*
+ * Unlink and rmdir VFS callbacks.
+ */
+static int pohmelfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+        return pohmelfs_remove_entry(dir, dentry);
+}
+
+static int pohmelfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+        int err;
+        struct inode *inode = dentry->d_inode;
+
+        dprintk("%s: parent: %llu, inode: %llu, name: '%s', parent_nlink: %d, nlink: %d.\n",
+                        __func__, POHMELFS_I(dir)->ino, POHMELFS_I(inode)->ino,
+                        dentry->d_name.name, (signed)dir->i_nlink, (signed)inode->i_nlink);
+
+        err = pohmelfs_remove_entry(dir, dentry);
+        if (!err) {
+                inode_dec_link_count(dir);
+                inode_dec_link_count(inode);
+        }
+
+        return err;
+}
+
+/*
+ * Link creation is synchronous.
+ * I'm lazy.
+ * Earth is somewhat round.
+ */
+static int pohmelfs_create_link(struct pohmelfs_inode *parent, struct qstr *obj,
+                struct pohmelfs_inode *target, struct qstr *tstr)
+{
+        struct super_block *sb = parent->vfs_inode.i_sb;
+        struct pohmelfs_sb *psb = POHMELFS_SB(sb);
+        struct netfs_cmd *cmd;
+        struct netfs_trans *t;
+        void *data;
+        int err, parent_len, target_len = 0, cur_len, path_size = 0;
+
+        err = pohmelfs_data_lock(parent, 0, ~0, POHMELFS_WRITE_LOCK);
+        if (err)
+                return err;
+
+        err = sb->s_op->write_inode(&parent->vfs_inode, 0);
+        if (err)
+                goto err_out_exit;
+
+        if (tstr)
+                target_len = tstr->len;
+
+        parent_len = pohmelfs_path_length(parent);
+        if (target)
+                target_len += pohmelfs_path_length(target);
+
+        if (parent_len < 0) {
+                err = parent_len;
+                goto err_out_exit;
+        }
+
+        if (target_len < 0) {
+                err = target_len;
+                goto err_out_exit;
+        }
+
+        t = netfs_trans_alloc(psb, parent_len + target_len + obj->len + 2, 0, 0);
+        if (!t) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+        cur_len = netfs_trans_cur_len(t);
+
+        cmd = netfs_trans_current(t);
+        if (IS_ERR(cmd)) {
+                err = PTR_ERR(cmd);
+                goto err_out_free;
+        }
+
+        data = (void *)(cmd + 1);
+        cur_len -= sizeof(struct netfs_cmd);
+
+        err = pohmelfs_construct_path_string(parent, data, parent_len);
+        if (err > 0) {
+                /* Do not place null-byte before the slash */
+                path_size = err - 1;
+                cur_len -= path_size;
+
+                err = snprintf(data + path_size, cur_len, "/%s|", obj->name);
+
+                path_size += err;
+                cur_len -= err;
+
+                cmd->ext = path_size - 1; /* No | symbol */
+
+                if (target) {
+                        err = pohmelfs_construct_path_string(target, data + path_size, target_len);
+                        if (err > 0) {
+                                path_size += err;
+                                cur_len -= err;
+                        }
+                }
+        }
+
+        if (err < 0)
+                goto err_out_free;
+
+        cmd->start = 0;
+
+        if (!target && tstr) {
+                if (tstr->len > cur_len - 1) {
+                        err = -ENAMETOOLONG;
+                        goto err_out_free;
+                }
+
+                err = snprintf(data + path_size, cur_len, "%s", tstr->name) + 1; /* 0-byte */
+                path_size += err;
+                cur_len -= err;
+                cmd->start = 1;
+        }
+
+        dprintk("%s: parent: %llu, obj: '%s', target_inode: %llu, target_str: '%s', full: '%s'.\n",
+                        __func__, parent->ino, obj->name, (target) ? target->ino : 0, (tstr) ? tstr->name : NULL,
+                        (char *)data);
+
+        cmd->cmd = NETFS_LINK;
+        cmd->size = path_size;
+        cmd->id = parent->ino;
+
+        netfs_convert_cmd(cmd);
+
+        netfs_trans_update(cmd, t, path_size);
+
+        err = netfs_trans_finish(t, psb);
+        if (err)
+                goto err_out_exit;
+
+        return 0;
+
+err_out_free:
+        t->result = err;
+        netfs_trans_put(t);
+err_out_exit:
+        return err;
+}
+
+/*
+ *  VFS hard and soft link callbacks.
+ */
+static int pohmelfs_link(struct dentry *old_dentry, struct inode *dir,
+        struct dentry *dentry)
+{
+        struct inode *inode = old_dentry->d_inode;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        int err;
+        struct qstr str = dentry->d_name;
+
+        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);
+
+        err = inode->i_sb->s_op->write_inode(inode, 0);
+        if (err)
+                return err;
+
+        err = pohmelfs_create_link(POHMELFS_I(dir), &str, pi, NULL);
+        if (err)
+                return err;
+
+        return pohmelfs_create_entry(dir, dentry, pi->ino, inode->i_mode);
+}
+
+static int pohmelfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+{
+        struct qstr sym_str;
+        struct qstr str = dentry->d_name;
+        struct inode *inode;
+        int err;
+
+        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);
+
+        sym_str.name = symname;
+        sym_str.len = strlen(symname);
+
+        err = pohmelfs_create_link(POHMELFS_I(dir), &str, NULL, &sym_str);
+        if (err)
+                goto err_out_exit;
+
+        err = pohmelfs_create_entry(dir, dentry, 0, S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO);
+        if (err)
+                goto err_out_exit;
+
+        inode = dentry->d_inode;
+
+        err = page_symlink(inode, symname, sym_str.len + 1);
+        if (err)
+                goto err_out_put;
+
+        return 0;
+
+err_out_put:
+        iput(inode);
+err_out_exit:
+        return err;
+}
+
+static int pohmelfs_send_rename(struct pohmelfs_inode *pi, struct pohmelfs_inode *parent,
+                struct qstr *str)
+{
+        int path_len, err, total_len = 0, inode_len, parent_len;
+        char *path;
+        struct netfs_trans *t;
+        struct netfs_cmd *cmd;
+        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
+
+        parent_len = pohmelfs_path_length(parent);
+        inode_len = pohmelfs_path_length(pi);
+
+        if (parent_len < 0 || inode_len < 0)
+                return -EINVAL;
+
+        path_len = parent_len + inode_len + str->len + 3;
+
+        t = netfs_trans_alloc(psb, path_len, 0, 0);
+        if (!t)
+                return -ENOMEM;
+
+        cmd = netfs_trans_current(t);
+        path = (char *)(cmd + 1);
+
+        err = pohmelfs_construct_path_string(pi, path, inode_len);
+        if (err < 0)
+                goto err_out_unlock;
+
+        cmd->ext = err;
+
+        path += err;
+        total_len += err;
+        path_len -= err;
+
+        *path = '|';
+        path++;
+        total_len++;
+        path_len--;
+
+        err = pohmelfs_construct_path_string(parent, path, parent_len);
+        if (err < 0)
+                goto err_out_unlock;
+
+        /*
+         * Do not place a null-byte before the final slash and the name.
+         */
+        err--;
+        path += err;
+        total_len += err;
+        path_len -= err;
+
+        err = snprintf(path, path_len - 1, "/%s", str->name);
+
+        total_len += err + 1; /* 0 symbol */
+        path_len -= err + 1;
+
+        cmd->cmd = NETFS_RENAME;
+        cmd->id = pi->ino;
+        cmd->start = parent->ino;
+        cmd->size = total_len;
+
+        netfs_convert_cmd(cmd);
+
+        netfs_trans_update(cmd, t, total_len);
+
+        return netfs_trans_finish(t, psb);
+
+err_out_unlock:
+        netfs_trans_free(t);
+        return err;
+}
+
+static int pohmelfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+                        struct inode *new_dir, struct dentry *new_dentry)
+{
+        struct inode *inode = old_dentry->d_inode;
+        struct pohmelfs_inode *old_parent, *pi, *new_parent;
+        struct qstr str = new_dentry->d_name;
+        struct pohmelfs_name *n;
+        unsigned int old_hash;
+        int err = -ENOENT;
+
+        pi = POHMELFS_I(inode);
+        old_parent = POHMELFS_I(old_dir);
+
+        if (new_dir)
+                new_dir->i_sb->s_op->write_inode(new_dir, 0);
+
+        old_hash = jhash(old_dentry->d_name.name, old_dentry->d_name.len, 0);
+        str.hash = jhash(new_dentry->d_name.name, new_dentry->d_name.len, 0);
+
+        str.len = new_dentry->d_name.len;
+        str.name = new_dentry->d_name.name;
+        str.hash = jhash(new_dentry->d_name.name, new_dentry->d_name.len, 0);
+
+        if (new_dir) {
+                new_parent = POHMELFS_I(new_dir);
+                err = -ENOTEMPTY;
+
+                if (S_ISDIR(inode->i_mode) &&
+                                new_parent->total_len <= 3)
+                        goto err_out_exit;
+        } else {
+                new_parent = old_parent;
+        }
+
+        dprintk("%s: ino: %llu, parent: %llu, name: '%s' -> parent: %llu, name: '%s', i_size: %llu.\n",
+                        __func__, pi->ino, old_parent->ino, old_dentry->d_name.name,
+                        new_parent->ino, new_dentry->d_name.name, inode->i_size);
+
+        if (test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state) &&
+                        test_bit(NETFS_INODE_OWNED, &pi->state)) {
+                err = pohmelfs_send_rename(pi, new_parent, &str);
+                if (err)
+                        goto err_out_exit;
+        }
+
+        n = pohmelfs_name_alloc(str.len + 1);
+        if (!n)
+                goto err_out_exit;
+
+        mutex_lock(&new_parent->offset_lock);
+        n->ino = pi->ino;
+        n->mode = inode->i_mode;
+        n->len = str.len;
+        n->hash = str.hash;
+        sprintf(n->data, "%s", str.name);
+
+        err = pohmelfs_insert_name(new_parent, n);
+        mutex_unlock(&new_parent->offset_lock);
+
+        if (err)
+                goto err_out_exit;
+
+        mutex_lock(&old_parent->offset_lock);
+        n = pohmelfs_search_hash(old_parent, old_hash);
+        if (n)
+                pohmelfs_name_del(old_parent, n);
+        mutex_unlock(&old_parent->offset_lock);
+
+        mark_inode_dirty(inode);
+        mark_inode_dirty(&new_parent->vfs_inode);
+
+        WARN_ON_ONCE(list_empty(&inode->i_dentry));
+
+        return 0;
+
+err_out_exit:
+
+        clear_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);
+
+        return err;
+}
+
+/*
+ * POHMELFS directory inode operations.
+ */
+const struct inode_operations pohmelfs_dir_inode_ops = {
+        .link           = pohmelfs_link,
+        .symlink        = pohmelfs_symlink,
+        .unlink         = pohmelfs_unlink,
+        .mkdir          = pohmelfs_mkdir,
+        .rmdir          = pohmelfs_rmdir,
+        .create         = pohmelfs_create,
+        .lookup         = pohmelfs_lookup,
+        .setattr        = pohmelfs_setattr,
+        .rename         = pohmelfs_rename,
+};
diff --git a/drivers/staging/pohmelfs/inode.c b/drivers/staging/pohmelfs/inode.c
new file mode 100644
index 00000000000..f3c6060c96b
--- /dev/null
+++ b/drivers/staging/pohmelfs/inode.c
@@ -0,0 +1,2056 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/backing-dev.h>
+#include <linux/crypto.h>
+#include <linux/fs.h>
+#include <linux/jhash.h>
+#include <linux/hash.h>
+#include <linux/ktime.h>
+#include <linux/mm.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/parser.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <linux/statfs.h>
+#include <linux/writeback.h>
+#include <linux/prefetch.h>
+
+#include "netfs.h"
+
+#define POHMELFS_MAGIC_NUM      0x504f482e
+
+static struct kmem_cache *pohmelfs_inode_cache;
+static atomic_t psb_bdi_num = ATOMIC_INIT(0);
+
+/*
+ * Removes inode from all trees, drops local name cache and removes all queued
+ * requests for object removal.
+ */
+void pohmelfs_inode_del_inode(struct pohmelfs_sb *psb, struct pohmelfs_inode *pi)
+{
+        mutex_lock(&pi->offset_lock);
+        pohmelfs_free_names(pi);
+        mutex_unlock(&pi->offset_lock);
+
+        dprintk("%s: deleted stuff in ino: %llu.\n", __func__, pi->ino);
+}
+
+/*
+ * Sync inode to server.
+ * Returns zero in success and negative error value otherwise.
+ * It will gather path to root directory into structures containing
+ * creation mode, permissions and names, so that the whole path
+ * to given inode could be created using only single network command.
+ */
+int pohmelfs_write_inode_create(struct inode *inode, struct netfs_trans *trans)
+{
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        int err = -ENOMEM, size;
+        struct netfs_cmd *cmd;
+        void *data;
+        int cur_len = netfs_trans_cur_len(trans);
+
+        if (unlikely(cur_len < 0))
+                return -ETOOSMALL;
+
+        cmd = netfs_trans_current(trans);
+        cur_len -= sizeof(struct netfs_cmd);
+
+        data = (void *)(cmd + 1);
+
+        err = pohmelfs_construct_path_string(pi, data, cur_len);
+        if (err < 0)
+                goto err_out_exit;
+
+        size = err;
+
+        cmd->start = i_size_read(inode);
+        cmd->cmd = NETFS_CREATE;
+        cmd->size = size;
+        cmd->id = pi->ino;
+        cmd->ext = inode->i_mode;
+
+        netfs_convert_cmd(cmd);
+
+        netfs_trans_update(cmd, trans, size);
+
+        return 0;
+
+err_out_exit:
+        printk("%s: completed ino: %llu, err: %d.\n", __func__, pi->ino, err);
+        return err;
+}
+
+static int pohmelfs_write_trans_complete(struct page **pages, unsigned int page_num,
+                void *private, int err)
+{
+        unsigned i;
+
+        dprintk("%s: pages: %lu-%lu, page_num: %u, err: %d.\n",
+                        __func__, pages[0]->index, pages[page_num-1]->index,
+                        page_num, err);
+
+        for (i = 0; i < page_num; i++) {
+                struct page *page = pages[i];
+
+                if (!page)
+                        continue;
+
+                end_page_writeback(page);
+
+                if (err < 0) {
+                        SetPageError(page);
+                        set_page_dirty(page);
+                }
+
+                unlock_page(page);
+                page_cache_release(page);
+
+                /* dprintk("%s: %3u/%u: page: %p.\n", __func__, i, page_num, page); */
+        }
+        return err;
+}
+
+static int pohmelfs_inode_has_dirty_pages(struct address_space *mapping, pgoff_t index)
+{
+        int ret;
+        struct page *page;
+
+        rcu_read_lock();
+        ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
+                                (void **)&page, index, 1, PAGECACHE_TAG_DIRTY);
+        rcu_read_unlock();
+        return ret;
+}
+
+static int pohmelfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+        struct inode *inode = mapping->host;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        int err = 0;
+        int done = 0;
+        int nr_pages;
+        pgoff_t index;
+        pgoff_t end;            /* Inclusive */
+        int scanned = 0;
+        int range_whole = 0;
+
+        if (wbc->range_cyclic) {
+                index = mapping->writeback_index; /* Start from prev offset */
+                end = -1;
+        } else {
+                index = wbc->range_start >> PAGE_CACHE_SHIFT;
+                end = wbc->range_end >> PAGE_CACHE_SHIFT;
+                if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
+                        range_whole = 1;
+                scanned = 1;
+        }
+retry:
+        while (!done && (index <= end)) {
+                unsigned int i = min(end - index, (pgoff_t)psb->trans_max_pages);
+                int path_len;
+                struct netfs_trans *trans;
+
+                err = pohmelfs_inode_has_dirty_pages(mapping, index);
+                if (!err)
+                        break;
+
+                err = pohmelfs_path_length(pi);
+                if (err < 0)
+                        break;
+
+                path_len = err;
+
+                if (path_len <= 2) {
+                        err = -ENOENT;
+                        break;
+                }
+
+                trans = netfs_trans_alloc(psb, path_len, 0, i);
+                if (!trans) {
+                        err = -ENOMEM;
+                        break;
+                }
+                trans->complete = &pohmelfs_write_trans_complete;
+
+                trans->page_num = nr_pages = find_get_pages_tag(mapping, &index,
+                                PAGECACHE_TAG_DIRTY, trans->page_num,
+                                trans->pages);
+
+                dprintk("%s: t: %p, nr_pages: %u, end: %lu, index: %lu, max: %u.\n",
+                                __func__, trans, nr_pages, end, index, trans->page_num);
+
+                if (!nr_pages)
+                        goto err_out_reset;
+
+                err = pohmelfs_write_inode_create(inode, trans);
+                if (err)
+                        goto err_out_reset;
+
+                err = 0;
+                scanned = 1;
+
+                for (i = 0; i < trans->page_num; i++) {
+                        struct page *page = trans->pages[i];
+
+                        lock_page(page);
+
+                        if (unlikely(page->mapping != mapping))
+                                goto out_continue;
+
+                        if (!wbc->range_cyclic && page->index > end) {
+                                done = 1;
+                                goto out_continue;
+                        }
+
+                        if (wbc->sync_mode != WB_SYNC_NONE)
+                                wait_on_page_writeback(page);
+
+                        if (PageWriteback(page) ||
+                            !clear_page_dirty_for_io(page)) {
+                                dprintk("%s: not clear for io page: %p, writeback: %d.\n",
+                                                __func__, page, PageWriteback(page));
+                                goto out_continue;
+                        }
+
+                        set_page_writeback(page);
+
+                        trans->attached_size += page_private(page);
+                        trans->attached_pages++;
+#if 0
+                        dprintk("%s: %u/%u added trans: %p, gen: %u, page: %p, [High: %d], size: %lu, idx: %lu.\n",
+                                        __func__, i, trans->page_num, trans, trans->gen, page,
+                                        !!PageHighMem(page), page_private(page), page->index);
+#endif
+                        wbc->nr_to_write--;
+
+                        if (wbc->nr_to_write <= 0)
+                                done = 1;
+
+                        continue;
+out_continue:
+                        unlock_page(page);
+                        trans->pages[i] = NULL;
+                }
+
+                err = netfs_trans_finish(trans, psb);
+                if (err)
+                        break;
+
+                continue;
+
+err_out_reset:
+                trans->result = err;
+                netfs_trans_reset(trans);
+                netfs_trans_put(trans);
+                break;
+        }
+
+        if (!scanned && !done) {
+                /*
+                 * We hit the last page and there is more work to be done: wrap
+                 * back to the start of the file
+                 */
+                scanned = 1;
+                index = 0;
+                goto retry;
+        }
+
+        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+                mapping->writeback_index = index;
+
+        return err;
+}
+
+/*
+ * Inode writeback creation completion callback.
+ * Only invoked for just created inodes, which do not have pages attached,
+ * like dirs and empty files.
+ */
+static int pohmelfs_write_inode_complete(struct page **pages, unsigned int page_num,
+                void *private, int err)
+{
+        struct inode *inode = private;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+
+        if (inode) {
+                if (err) {
+                        mark_inode_dirty(inode);
+                        clear_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);
+                } else {
+                        set_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);
+                }
+
+                pohmelfs_put_inode(pi);
+        }
+
+        return err;
+}
+
+int pohmelfs_write_create_inode(struct pohmelfs_inode *pi)
+{
+        struct netfs_trans *t;
+        struct inode *inode = &pi->vfs_inode;
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        int err;
+
+        if (test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state))
+                return 0;
+
+        dprintk("%s: started ino: %llu.\n", __func__, pi->ino);
+
+        err = pohmelfs_path_length(pi);
+        if (err < 0)
+                goto err_out_exit;
+
+        t = netfs_trans_alloc(psb, err + 1, 0, 0);
+        if (!t) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+        t->complete = pohmelfs_write_inode_complete;
+        t->private = igrab(inode);
+        if (!t->private) {
+                err = -ENOENT;
+                goto err_out_put;
+        }
+
+        err = pohmelfs_write_inode_create(inode, t);
+        if (err)
+                goto err_out_put;
+
+        netfs_trans_finish(t, POHMELFS_SB(inode->i_sb));
+
+        return 0;
+
+err_out_put:
+        t->result = err;
+        netfs_trans_put(t);
+err_out_exit:
+        return err;
+}
+
+/*
+ * Sync all not-yet-created children in given directory to the server.
+ */
+static int pohmelfs_write_inode_create_children(struct inode *inode)
+{
+        struct pohmelfs_inode *parent = POHMELFS_I(inode);
+        struct super_block *sb = inode->i_sb;
+        struct pohmelfs_name *n;
+
+        while (!list_empty(&parent->sync_create_list)) {
+                n = NULL;
+                mutex_lock(&parent->offset_lock);
+                if (!list_empty(&parent->sync_create_list)) {
+                        n = list_first_entry(&parent->sync_create_list,
+                                struct pohmelfs_name, sync_create_entry);
+                        list_del_init(&n->sync_create_entry);
+                }
+                mutex_unlock(&parent->offset_lock);
+
+                if (!n)
+                        break;
+
+                inode = ilookup(sb, n->ino);
+
+                dprintk("%s: parent: %llu, ino: %llu, inode: %p.\n",
+                                __func__, parent->ino, n->ino, inode);
+
+                if (inode && (inode->i_state & I_DIRTY)) {
+                        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+                        pohmelfs_write_create_inode(pi);
+                        /* pohmelfs_meta_command(pi, NETFS_INODE_INFO, 0, NULL, NULL, 0); */
+                        iput(inode);
+                }
+        }
+
+        return 0;
+}
+
+/*
+ * Removes given child from given inode on server.
+ */
+int pohmelfs_remove_child(struct pohmelfs_inode *pi, struct pohmelfs_name *n)
+{
+        return pohmelfs_meta_command_data(pi, pi->ino, NETFS_REMOVE, NULL, 0, NULL, NULL, 0);
+}
+
+/*
+ * Writeback for given inode.
+ */
+static int pohmelfs_write_inode(struct inode *inode,
+                                struct writeback_control *wbc)
+{
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+
+        pohmelfs_write_create_inode(pi);
+        pohmelfs_write_inode_create_children(inode);
+
+        return 0;
+}
+
+/*
+ * It is not exported, sorry...
+ */
+static inline wait_queue_head_t *page_waitqueue(struct page *page)
+{
+        const struct zone *zone = page_zone(page);
+
+        return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
+}
+
+static int pohmelfs_wait_on_page_locked(struct page *page)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(page->mapping->host->i_sb);
+        long ret = psb->wait_on_page_timeout;
+        DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
+        int err = 0;
+
+        if (!PageLocked(page))
+                return 0;
+
+        for (;;) {
+                prepare_to_wait(page_waitqueue(page),
+                                &wait.wait, TASK_INTERRUPTIBLE);
+
+                dprintk("%s: page: %p, locked: %d, uptodate: %d, error: %d, flags: %lx.\n",
+                                __func__, page, PageLocked(page), PageUptodate(page),
+                                PageError(page), page->flags);
+
+                if (!PageLocked(page))
+                        break;
+
+                if (!signal_pending(current)) {
+                        ret = schedule_timeout(ret);
+                        if (!ret)
+                                break;
+                        continue;
+                }
+                ret = -ERESTARTSYS;
+                break;
+        }
+        finish_wait(page_waitqueue(page), &wait.wait);
+
+        if (!ret)
+                err = -ETIMEDOUT;
+
+
+        if (!err)
+                SetPageUptodate(page);
+
+        if (err)
+                printk("%s: page: %p, uptodate: %d, locked: %d, err: %d.\n",
+                        __func__, page, PageUptodate(page), PageLocked(page), err);
+
+        return err;
+}
+
+static int pohmelfs_read_page_complete(struct page **pages, unsigned int page_num,
+                void *private, int err)
+{
+        struct page *page = private;
+
+        if (PageChecked(page))
+                return err;
+
+        if (err < 0) {
+                dprintk("%s: page: %p, err: %d.\n", __func__, page, err);
+                SetPageError(page);
+        }
+
+        unlock_page(page);
+
+        return err;
+}
+
+/*
+ * Read a page from remote server.
+ * Function will wait until page is unlocked.
+ */
+static int pohmelfs_readpage(struct file *file, struct page *page)
+{
+        struct inode *inode = page->mapping->host;
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        struct netfs_trans *t;
+        struct netfs_cmd *cmd;
+        int err, path_len;
+        void *data;
+        u64 isize;
+
+        err = pohmelfs_data_lock(pi, page->index << PAGE_CACHE_SHIFT,
+                        PAGE_SIZE, POHMELFS_READ_LOCK);
+        if (err)
+                goto err_out_exit;
+
+        isize = i_size_read(inode);
+        if (isize <= page->index << PAGE_CACHE_SHIFT) {
+                SetPageUptodate(page);
+                unlock_page(page);
+                return 0;
+        }
+
+        path_len = pohmelfs_path_length(pi);
+        if (path_len < 0) {
+                err = path_len;
+                goto err_out_exit;
+        }
+
+        t = netfs_trans_alloc(psb, path_len, NETFS_TRANS_SINGLE_DST, 0);
+        if (!t) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+
+        t->complete = pohmelfs_read_page_complete;
+        t->private = page;
+
+        cmd = netfs_trans_current(t);
+        data = (void *)(cmd + 1);
+
+        err = pohmelfs_construct_path_string(pi, data, path_len);
+        if (err < 0)
+                goto err_out_free;
+
+        path_len = err;
+
+        cmd->id = pi->ino;
+        cmd->start = page->index;
+        cmd->start <<= PAGE_CACHE_SHIFT;
+        cmd->size = PAGE_CACHE_SIZE + path_len;
+        cmd->cmd = NETFS_READ_PAGE;
+        cmd->ext = path_len;
+
+        dprintk("%s: path: '%s', page: %p, ino: %llu, start: %llu, size: %lu.\n",
+                        __func__, (char *)data, page, pi->ino, cmd->start, PAGE_CACHE_SIZE);
+
+        netfs_convert_cmd(cmd);
+        netfs_trans_update(cmd, t, path_len);
+
+        err = netfs_trans_finish(t, psb);
+        if (err)
+                goto err_out_return;
+
+        return pohmelfs_wait_on_page_locked(page);
+
+err_out_free:
+        t->result = err;
+        netfs_trans_put(t);
+err_out_exit:
+        SetPageError(page);
+        if (PageLocked(page))
+                unlock_page(page);
+err_out_return:
+        printk("%s: page: %p, start: %lu, size: %lu, err: %d.\n",
+                __func__, page, page->index << PAGE_CACHE_SHIFT, PAGE_CACHE_SIZE, err);
+
+        return err;
+}
+
+/*
+ * Write begin/end magic.
+ * Allocates a page and writes inode if it was not synced to server before.
+ */
+static int pohmelfs_write_begin(struct file *file, struct address_space *mapping,
+                loff_t pos, unsigned len, unsigned flags,
+                struct page **pagep, void **fsdata)
+{
+        struct inode *inode = mapping->host;
+        struct page *page;
+        pgoff_t index;
+        unsigned start, end;
+        int err;
+
+        *pagep = NULL;
+
+        index = pos >> PAGE_CACHE_SHIFT;
+        start = pos & (PAGE_CACHE_SIZE - 1);
+        end = start + len;
+
+        page = grab_cache_page(mapping, index);
+#if 0
+        dprintk("%s: page: %p pos: %llu, len: %u, index: %lu, start: %u, end: %u, uptodate: %d.\n",
+                        __func__, page, pos, len, index, start, end, PageUptodate(page));
+#endif
+        if (!page) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+
+        while (!PageUptodate(page)) {
+                if (start && test_bit(NETFS_INODE_REMOTE_SYNCED, &POHMELFS_I(inode)->state)) {
+                        err = pohmelfs_readpage(file, page);
+                        if (err)
+                                goto err_out_exit;
+
+                        lock_page(page);
+                        continue;
+                }
+
+                if (len != PAGE_CACHE_SIZE) {
+                        void *kaddr = kmap_atomic(page, KM_USER0);
+
+                        memset(kaddr + start, 0, PAGE_CACHE_SIZE - start);
+                        flush_dcache_page(page);
+                        kunmap_atomic(kaddr, KM_USER0);
+                }
+                SetPageUptodate(page);
+        }
+
+        set_page_private(page, end);
+
+        *pagep = page;
+
+        return 0;
+
+err_out_exit:
+        page_cache_release(page);
+        *pagep = NULL;
+
+        return err;
+}
+
+static int pohmelfs_write_end(struct file *file, struct address_space *mapping,
+                        loff_t pos, unsigned len, unsigned copied,
+                        struct page *page, void *fsdata)
+{
+        struct inode *inode = mapping->host;
+
+        if (copied != len) {
+                unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+                void *kaddr = kmap_atomic(page, KM_USER0);
+
+                memset(kaddr + from + copied, 0, len - copied);
+                flush_dcache_page(page);
+                kunmap_atomic(kaddr, KM_USER0);
+        }
+
+        SetPageUptodate(page);
+        set_page_dirty(page);
+#if 0
+        dprintk("%s: page: %p [U: %d, D: %d, L: %d], pos: %llu, len: %u, copied: %u.\n",
+                        __func__, page,
+                        PageUptodate(page), PageDirty(page), PageLocked(page),
+                        pos, len, copied);
+#endif
+        flush_dcache_page(page);
+
+        unlock_page(page);
+        page_cache_release(page);
+
+        if (pos + copied > inode->i_size) {
+                struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+
+                psb->avail_size -= pos + copied - inode->i_size;
+
+                i_size_write(inode, pos + copied);
+        }
+
+        return copied;
+}
+
+static int pohmelfs_readpages_trans_complete(struct page **__pages, unsigned int page_num,
+                void *private, int err)
+{
+        struct pohmelfs_inode *pi = private;
+        unsigned int i, num;
+        struct page **pages, *page = (struct page *)__pages;
+        loff_t index = page->index;
+
+        pages = kzalloc(sizeof(void *) * page_num, GFP_NOIO);
+        if (!pages)
+                return -ENOMEM;
+
+        num = find_get_pages_contig(pi->vfs_inode.i_mapping, index, page_num, pages);
+        if (num <= 0) {
+                err = num;
+                goto err_out_free;
+        }
+
+        for (i = 0; i < num; ++i) {
+                page = pages[i];
+
+                if (err)
+                        printk("%s: %u/%u: page: %p, index: %lu, uptodate: %d, locked: %d, err: %d.\n",
+                                __func__, i, num, page, page->index,
+                                PageUptodate(page), PageLocked(page), err);
+
+                if (!PageChecked(page)) {
+                        if (err < 0)
+                                SetPageError(page);
+                        unlock_page(page);
+                }
+                page_cache_release(page);
+                page_cache_release(page);
+        }
+
+err_out_free:
+        kfree(pages);
+        return err;
+}
+
+static int pohmelfs_send_readpages(struct pohmelfs_inode *pi, struct page *first, unsigned int num)
+{
+        struct netfs_trans *t;
+        struct netfs_cmd *cmd;
+        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
+        int err, path_len;
+        void *data;
+
+        err = pohmelfs_data_lock(pi, first->index << PAGE_CACHE_SHIFT,
+                        num * PAGE_SIZE, POHMELFS_READ_LOCK);
+        if (err)
+                goto err_out_exit;
+
+        path_len = pohmelfs_path_length(pi);
+        if (path_len < 0) {
+                err = path_len;
+                goto err_out_exit;
+        }
+
+        t = netfs_trans_alloc(psb, path_len, NETFS_TRANS_SINGLE_DST, 0);
+        if (!t) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+
+        cmd = netfs_trans_current(t);
+        data = (void *)(cmd + 1);
+
+        t->complete = pohmelfs_readpages_trans_complete;
+        t->private = pi;
+        t->page_num = num;
+        t->pages = (struct page **)first;
+
+        err = pohmelfs_construct_path_string(pi, data, path_len);
+        if (err < 0)
+                goto err_out_put;
+
+        path_len = err;
+
+        cmd->cmd = NETFS_READ_PAGES;
+        cmd->start = first->index;
+        cmd->start <<= PAGE_CACHE_SHIFT;
+        cmd->size = (num << 8 | PAGE_CACHE_SHIFT);
+        cmd->id = pi->ino;
+        cmd->ext = path_len;
+
+        dprintk("%s: t: %p, gen: %u, path: '%s', path_len: %u, "
+                        "start: %lu, num: %u.\n",
+                        __func__, t, t->gen, (char *)data, path_len,
+                        first->index, num);
+
+        netfs_convert_cmd(cmd);
+        netfs_trans_update(cmd, t, path_len);
+
+        return netfs_trans_finish(t, psb);
+
+err_out_put:
+        netfs_trans_free(t);
+err_out_exit:
+        pohmelfs_readpages_trans_complete((struct page **)first, num, pi, err);
+        return err;
+}
+
+#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
+
+static int pohmelfs_readpages(struct file *file, struct address_space *mapping,
+                        struct list_head *pages, unsigned nr_pages)
+{
+        unsigned int page_idx, num = 0;
+        struct page *page = NULL, *first = NULL;
+
+        for (page_idx = 0; page_idx < nr_pages; page_idx++) {
+                page = list_to_page(pages);
+
+                prefetchw(&page->flags);
+                list_del(&page->lru);
+
+                if (!add_to_page_cache_lru(page, mapping,
+                                        page->index, GFP_KERNEL)) {
+
+                        if (!num) {
+                                num = 1;
+                                first = page;
+                                continue;
+                        }
+
+                        dprintk("%s: added to lru page: %p, page_index: %lu, first_index: %lu.\n",
+                                        __func__, page, page->index, first->index);
+
+                        if (unlikely(first->index + num != page->index) || (num > 500)) {
+                                pohmelfs_send_readpages(POHMELFS_I(mapping->host),
+                                                first, num);
+                                first = page;
+                                num = 0;
+                        }
+
+                        num++;
+                }
+        }
+        pohmelfs_send_readpages(POHMELFS_I(mapping->host), first, num);
+
+        /*
+         * This will be sync read, so when last page is processed,
+         * all previous are alerady unlocked and ready to be used.
+         */
+        return 0;
+}
+
+/*
+ * Small address space operations for POHMELFS.
+ */
+const struct address_space_operations pohmelfs_aops = {
+        .readpage               = pohmelfs_readpage,
+        .readpages              = pohmelfs_readpages,
+        .writepages             = pohmelfs_writepages,
+        .write_begin            = pohmelfs_write_begin,
+        .write_end              = pohmelfs_write_end,
+        .set_page_dirty         = __set_page_dirty_nobuffers,
+};
+
+static void pohmelfs_i_callback(struct rcu_head *head)
+{
+        struct inode *inode = container_of(head, struct inode, i_rcu);
+        INIT_LIST_HEAD(&inode->i_dentry);
+        kmem_cache_free(pohmelfs_inode_cache, POHMELFS_I(inode));
+}
+
+/*
+ * ->destroy_inode() callback. Deletes inode from the caches
+ *  and frees private data.
+ */
+static void pohmelfs_destroy_inode(struct inode *inode)
+{
+        struct super_block *sb = inode->i_sb;
+        struct pohmelfs_sb *psb = POHMELFS_SB(sb);
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+
+        /* pohmelfs_data_unlock(pi, 0, inode->i_size, POHMELFS_READ_LOCK); */
+
+        pohmelfs_inode_del_inode(psb, pi);
+
+        dprintk("%s: pi: %p, inode: %p, ino: %llu.\n",
+                __func__, pi, &pi->vfs_inode, pi->ino);
+        atomic_long_dec(&psb->total_inodes);
+        call_rcu(&inode->i_rcu, pohmelfs_i_callback);
+}
+
+/*
+ * ->alloc_inode() callback. Allocates inode and initializes private data.
+ */
+static struct inode *pohmelfs_alloc_inode(struct super_block *sb)
+{
+        struct pohmelfs_inode *pi;
+
+        pi = kmem_cache_alloc(pohmelfs_inode_cache, GFP_NOIO);
+        if (!pi)
+                return NULL;
+
+        pi->hash_root = RB_ROOT;
+        mutex_init(&pi->offset_lock);
+
+        INIT_LIST_HEAD(&pi->sync_create_list);
+
+        INIT_LIST_HEAD(&pi->inode_entry);
+
+        pi->lock_type = 0;
+        pi->state = 0;
+        pi->total_len = 0;
+        pi->drop_count = 0;
+
+        dprintk("%s: pi: %p, inode: %p.\n", __func__, pi, &pi->vfs_inode);
+
+        atomic_long_inc(&POHMELFS_SB(sb)->total_inodes);
+
+        return &pi->vfs_inode;
+}
+
+/*
+ * We want fsync() to work on POHMELFS.
+ */
+static int pohmelfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+        struct inode *inode = file->f_mapping->host;
+        int err = filemap_write_and_wait_range(inode->i_mapping, start, end);
+        if (!err) {
+                mutex_lock(&inode->i_mutex);
+                err = sync_inode_metadata(inode, 1);
+                mutex_unlock(&inode->i_mutex);
+        }
+        return err;
+}
+
+ssize_t pohmelfs_write(struct file *file, const char __user *buf,
+                size_t len, loff_t *ppos)
+{
+        struct address_space *mapping = file->f_mapping;
+        struct inode *inode = mapping->host;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
+        struct kiocb kiocb;
+        ssize_t ret;
+        loff_t pos = *ppos;
+
+        init_sync_kiocb(&kiocb, file);
+        kiocb.ki_pos = pos;
+        kiocb.ki_left = len;
+
+        dprintk("%s: len: %zu, pos: %llu.\n", __func__, len, pos);
+
+        mutex_lock(&inode->i_mutex);
+        ret = pohmelfs_data_lock(pi, pos, len, POHMELFS_WRITE_LOCK);
+        if (ret)
+                goto err_out_unlock;
+
+        ret = __generic_file_aio_write(&kiocb, &iov, 1, &kiocb.ki_pos);
+        *ppos = kiocb.ki_pos;
+
+        mutex_unlock(&inode->i_mutex);
+        WARN_ON(ret < 0);
+
+        if (ret > 0) {
+                ssize_t err;
+
+                err = generic_write_sync(file, pos, ret);
+                if (err < 0)
+                        ret = err;
+                WARN_ON(ret < 0);
+        }
+
+        return ret;
+
+err_out_unlock:
+        mutex_unlock(&inode->i_mutex);
+        return ret;
+}
+
+static const struct file_operations pohmelfs_file_ops = {
+        .open           = generic_file_open,
+        .fsync          = pohmelfs_fsync,
+
+        .llseek         = generic_file_llseek,
+
+        .read           = do_sync_read,
+        .aio_read       = generic_file_aio_read,
+
+        .mmap           = generic_file_mmap,
+
+        .splice_read    = generic_file_splice_read,
+        .splice_write   = generic_file_splice_write,
+
+        .write          = pohmelfs_write,
+        .aio_write      = generic_file_aio_write,
+};
+
+const struct inode_operations pohmelfs_symlink_inode_operations = {
+        .readlink       = generic_readlink,
+        .follow_link    = page_follow_link_light,
+        .put_link       = page_put_link,
+};
+
+int pohmelfs_setattr_raw(struct inode *inode, struct iattr *attr)
+{
+        int err;
+
+        err = inode_change_ok(inode, attr);
+        if (err) {
+                dprintk("%s: ino: %llu, inode changes are not allowed.\n", __func__, POHMELFS_I(inode)->ino);
+                goto err_out_exit;
+        }
+
+        if ((attr->ia_valid & ATTR_SIZE) &&
+            attr->ia_size != i_size_read(inode)) {
+                err = vmtruncate(inode, attr->ia_size);
+                if (err) {
+                        dprintk("%s: ino: %llu, failed to set the attributes.\n", __func__, POHMELFS_I(inode)->ino);
+                        goto err_out_exit;
+                }
+        }
+
+        setattr_copy(inode, attr);
+        mark_inode_dirty(inode);
+
+        dprintk("%s: ino: %llu, mode: %o -> %o, uid: %u -> %u, gid: %u -> %u, size: %llu -> %llu.\n",
+                        __func__, POHMELFS_I(inode)->ino, inode->i_mode, attr->ia_mode,
+                        inode->i_uid, attr->ia_uid, inode->i_gid, attr->ia_gid, inode->i_size, attr->ia_size);
+
+        return 0;
+
+err_out_exit:
+        return err;
+}
+
+int pohmelfs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+        struct inode *inode = dentry->d_inode;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        int err;
+
+        err = pohmelfs_data_lock(pi, 0, ~0, POHMELFS_WRITE_LOCK);
+        if (err)
+                goto err_out_exit;
+
+        err = security_inode_setattr(dentry, attr);
+        if (err)
+                goto err_out_exit;
+
+        err = pohmelfs_setattr_raw(inode, attr);
+        if (err)
+                goto err_out_exit;
+
+        return 0;
+
+err_out_exit:
+        return err;
+}
+
+static int pohmelfs_send_xattr_req(struct pohmelfs_inode *pi, u64 id, u64 start,
+                const char *name, const void *value, size_t attrsize, int command)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
+        int err, path_len, namelen = strlen(name) + 1; /* 0-byte */
+        struct netfs_trans *t;
+        struct netfs_cmd *cmd;
+        void *data;
+
+        dprintk("%s: id: %llu, start: %llu, name: '%s', attrsize: %zu, cmd: %d.\n",
+                        __func__, id, start, name, attrsize, command);
+
+        path_len = pohmelfs_path_length(pi);
+        if (path_len < 0) {
+                err = path_len;
+                goto err_out_exit;
+        }
+
+        t = netfs_trans_alloc(psb, namelen + path_len + attrsize, 0, 0);
+        if (!t) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+
+        cmd = netfs_trans_current(t);
+        data = cmd + 1;
+
+        path_len = pohmelfs_construct_path_string(pi, data, path_len);
+        if (path_len < 0) {
+                err = path_len;
+                goto err_out_put;
+        }
+        data += path_len;
+
+        /*
+         * 'name' is a NUL-terminated string already and
+         * 'namelen' includes 0-byte.
+         */
+        memcpy(data, name, namelen);
+        data += namelen;
+
+        memcpy(data, value, attrsize);
+
+        cmd->cmd = command;
+        cmd->id = id;
+        cmd->start = start;
+        cmd->size = attrsize + namelen + path_len;
+        cmd->ext = path_len;
+        cmd->csize = 0;
+        cmd->cpad = 0;
+
+        netfs_convert_cmd(cmd);
+        netfs_trans_update(cmd, t, namelen + path_len + attrsize);
+
+        return netfs_trans_finish(t, psb);
+
+err_out_put:
+        t->result = err;
+        netfs_trans_put(t);
+err_out_exit:
+        return err;
+}
+
+static int pohmelfs_setxattr(struct dentry *dentry, const char *name,
+                const void *value, size_t attrsize, int flags)
+{
+        struct inode *inode = dentry->d_inode;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+
+        if (!(psb->state_flags & POHMELFS_FLAGS_XATTR))
+                return -EOPNOTSUPP;
+
+        return pohmelfs_send_xattr_req(pi, flags, attrsize, name,
+                        value, attrsize, NETFS_XATTR_SET);
+}
+
+static ssize_t pohmelfs_getxattr(struct dentry *dentry, const char *name,
+                void *value, size_t attrsize)
+{
+        struct inode *inode = dentry->d_inode;
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        struct pohmelfs_mcache *m;
+        int err;
+        long timeout = psb->mcache_timeout;
+
+        if (!(psb->state_flags & POHMELFS_FLAGS_XATTR))
+                return -EOPNOTSUPP;
+
+        m = pohmelfs_mcache_alloc(psb, 0, attrsize, value);
+        if (IS_ERR(m))
+                return PTR_ERR(m);
+
+        dprintk("%s: ino: %llu, name: '%s', size: %zu.\n",
+                        __func__, pi->ino, name, attrsize);
+
+        err = pohmelfs_send_xattr_req(pi, m->gen, attrsize, name, value, 0, NETFS_XATTR_GET);
+        if (err)
+                goto err_out_put;
+
+        do {
+                err = wait_for_completion_timeout(&m->complete, timeout);
+                if (err) {
+                        err = m->err;
+                        break;
+                }
+
+                /*
+                 * This loop is a bit ugly, since it waits until reference counter
+                 * hits 1 and then puts the object here. Main goal is to prevent race with
+                 * the network thread, when it can start processing the given request, i.e.
+                 * increase its reference counter but yet not complete it, while
+                 * we will exit from ->getxattr() with timeout, and although request
+                 * will not be freed (its reference counter was increased by network
+                 * thread), data pointer provided by user may be released, so we will
+                 * overwrite an already freed area in the network thread.
+                 *
+                 * Now after timeout we remove request from the cache, so it can not be
+                 * found by network thread, and wait for its reference counter to hit 1,
+                 * i.e. if network thread already started to process this request, we wait
+                 * for it to finish, and then free object locally. If reference counter is
+                 * already 1, i.e. request is not used by anyone else, we can free it without
+                 * problem.
+                 */
+                err = -ETIMEDOUT;
+                timeout = HZ;
+
+                pohmelfs_mcache_remove_locked(psb, m);
+        } while (atomic_read(&m->refcnt) != 1);
+
+        pohmelfs_mcache_put(psb, m);
+
+        dprintk("%s: ino: %llu, err: %d.\n", __func__, pi->ino, err);
+
+        return err;
+
+err_out_put:
+        pohmelfs_mcache_put(psb, m);
+        return err;
+}
+
+static int pohmelfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+        struct inode *inode = dentry->d_inode;
+#if 0
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+        int err;
+
+        err = pohmelfs_data_lock(pi, 0, ~0, POHMELFS_READ_LOCK);
+        if (err)
+                return err;
+        dprintk("%s: ino: %llu, mode: %o, uid: %u, gid: %u, size: %llu.\n",
+                        __func__, pi->ino, inode->i_mode, inode->i_uid,
+                        inode->i_gid, inode->i_size);
+#endif
+
+        generic_fillattr(inode, stat);
+        return 0;
+}
+
+const struct inode_operations pohmelfs_file_inode_operations = {
+        .setattr        = pohmelfs_setattr,
+        .getattr        = pohmelfs_getattr,
+        .setxattr       = pohmelfs_setxattr,
+        .getxattr       = pohmelfs_getxattr,
+};
+
+/*
+ * Fill inode data: mode, size, operation callbacks and so on...
+ */
+void pohmelfs_fill_inode(struct inode *inode, struct netfs_inode_info *info)
+{
+        inode->i_mode = info->mode;
+        inode->i_nlink = info->nlink;
+        inode->i_uid = info->uid;
+        inode->i_gid = info->gid;
+        inode->i_blocks = info->blocks;
+        inode->i_rdev = info->rdev;
+        inode->i_size = info->size;
+        inode->i_version = info->version;
+        inode->i_blkbits = ffs(info->blocksize);
+
+        dprintk("%s: inode: %p, num: %lu/%llu inode is regular: %d, dir: %d, link: %d, mode: %o, size: %llu.\n",
+                        __func__, inode, inode->i_ino, info->ino,
+                        S_ISREG(inode->i_mode), S_ISDIR(inode->i_mode),
+                        S_ISLNK(inode->i_mode), inode->i_mode, inode->i_size);
+
+        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
+
+        /*
+         * i_mapping is a pointer to i_data during inode initialization.
+         */
+        inode->i_data.a_ops = &pohmelfs_aops;
+
+        if (S_ISREG(inode->i_mode)) {
+                inode->i_fop = &pohmelfs_file_ops;
+                inode->i_op = &pohmelfs_file_inode_operations;
+        } else if (S_ISDIR(inode->i_mode)) {
+                inode->i_fop = &pohmelfs_dir_fops;
+                inode->i_op = &pohmelfs_dir_inode_ops;
+        } else if (S_ISLNK(inode->i_mode)) {
+                inode->i_op = &pohmelfs_symlink_inode_operations;
+                inode->i_fop = &pohmelfs_file_ops;
+        } else {
+                inode->i_fop = &generic_ro_fops;
+        }
+}
+
+static int pohmelfs_drop_inode(struct inode *inode)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        struct pohmelfs_inode *pi = POHMELFS_I(inode);
+
+        spin_lock(&psb->ino_lock);
+        list_del_init(&pi->inode_entry);
+        spin_unlock(&psb->ino_lock);
+
+        return generic_drop_inode(inode);
+}
+
+static struct pohmelfs_inode *pohmelfs_get_inode_from_list(struct pohmelfs_sb *psb,
+                struct list_head *head, unsigned int *count)
+{
+        struct pohmelfs_inode *pi = NULL;
+
+        spin_lock(&psb->ino_lock);
+        if (!list_empty(head)) {
+                pi = list_entry(head->next, struct pohmelfs_inode,
+                                        inode_entry);
+                list_del_init(&pi->inode_entry);
+                *count = pi->drop_count;
+                pi->drop_count = 0;
+        }
+        spin_unlock(&psb->ino_lock);
+
+        return pi;
+}
+
+static void pohmelfs_flush_transactions(struct pohmelfs_sb *psb)
+{
+        struct pohmelfs_config *c;
+
+        mutex_lock(&psb->state_lock);
+        list_for_each_entry(c, &psb->state_list, config_entry) {
+                pohmelfs_state_flush_transactions(&c->state);
+        }
+        mutex_unlock(&psb->state_lock);
+}
+
+/*
+ * ->put_super() callback. Invoked before superblock is destroyed,
+ *  so it has to clean all private data.
+ */
+static void pohmelfs_put_super(struct super_block *sb)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(sb);
+        struct pohmelfs_inode *pi;
+        unsigned int count = 0;
+        unsigned int in_drop_list = 0;
+        struct inode *inode, *tmp;
+
+        dprintk("%s.\n", __func__);
+
+        /*
+         * Kill pending transactions, which could affect inodes in-flight.
+         */
+        pohmelfs_flush_transactions(psb);
+
+        while ((pi = pohmelfs_get_inode_from_list(psb, &psb->drop_list, &count))) {
+                inode = &pi->vfs_inode;
+
+                dprintk("%s: ino: %llu, pi: %p, inode: %p, count: %u.\n",
+                                __func__, pi->ino, pi, inode, count);
+
+                if (atomic_read(&inode->i_count) != count) {
+                        printk("%s: ino: %llu, pi: %p, inode: %p, count: %u, i_count: %d.\n",
+                                        __func__, pi->ino, pi, inode, count,
+                                        atomic_read(&inode->i_count));
+                        count = atomic_read(&inode->i_count);
+                        in_drop_list++;
+                }
+
+                while (count--)
+                        iput(&pi->vfs_inode);
+        }
+
+        list_for_each_entry_safe(inode, tmp, &sb->s_inodes, i_sb_list) {
+                pi = POHMELFS_I(inode);
+
+                dprintk("%s: ino: %llu, pi: %p, inode: %p, i_count: %u.\n",
+                                __func__, pi->ino, pi, inode, atomic_read(&inode->i_count));
+
+                /*
+                 * These are special inodes, they were created during
+                 * directory reading or lookup, and were not bound to dentry,
+                 * so they live here with reference counter being 1 and prevent
+                 * umount from succeed since it believes that they are busy.
+                 */
+                count = atomic_read(&inode->i_count);
+                if (count) {
+                        list_del_init(&inode->i_sb_list);
+                        while (count--)
+                                iput(&pi->vfs_inode);
+                }
+        }
+
+        psb->trans_scan_timeout = psb->drop_scan_timeout = 0;
+        cancel_delayed_work_sync(&psb->dwork);
+        cancel_delayed_work_sync(&psb->drop_dwork);
+        flush_scheduled_work();
+
+        dprintk("%s: stopped workqueues.\n", __func__);
+
+        pohmelfs_crypto_exit(psb);
+        pohmelfs_state_exit(psb);
+
+        bdi_destroy(&psb->bdi);
+
+        kfree(psb);
+        sb->s_fs_info = NULL;
+}
+
+static int pohmelfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+        struct super_block *sb = dentry->d_sb;
+        struct pohmelfs_sb *psb = POHMELFS_SB(sb);
+
+        /*
+         * There are no filesystem size limits yet.
+         */
+        memset(buf, 0, sizeof(struct kstatfs));
+
+        buf->f_type = POHMELFS_MAGIC_NUM; /* 'POH.' */
+        buf->f_bsize = sb->s_blocksize;
+        buf->f_files = psb->ino;
+        buf->f_namelen = 255;
+        buf->f_files = atomic_long_read(&psb->total_inodes);
+        buf->f_bfree = buf->f_bavail = psb->avail_size >> PAGE_SHIFT;
+        buf->f_blocks = psb->total_size >> PAGE_SHIFT;
+
+        dprintk("%s: total: %llu, avail: %llu, inodes: %llu, bsize: %lu.\n",
+                __func__, psb->total_size, psb->avail_size, buf->f_files, sb->s_blocksize);
+
+        return 0;
+}
+
+static int pohmelfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(vfs->mnt_sb);
+
+        seq_printf(seq, ",idx=%u", psb->idx);
+        seq_printf(seq, ",trans_scan_timeout=%u", jiffies_to_msecs(psb->trans_scan_timeout));
+        seq_printf(seq, ",drop_scan_timeout=%u", jiffies_to_msecs(psb->drop_scan_timeout));
+        seq_printf(seq, ",wait_on_page_timeout=%u", jiffies_to_msecs(psb->wait_on_page_timeout));
+        seq_printf(seq, ",trans_retries=%u", psb->trans_retries);
+        seq_printf(seq, ",crypto_thread_num=%u", psb->crypto_thread_num);
+        seq_printf(seq, ",trans_max_pages=%u", psb->trans_max_pages);
+        seq_printf(seq, ",mcache_timeout=%u", jiffies_to_msecs(psb->mcache_timeout));
+        if (psb->crypto_fail_unsupported)
+                seq_printf(seq, ",crypto_fail_unsupported");
+
+        return 0;
+}
+
+enum {
+        pohmelfs_opt_idx,
+        pohmelfs_opt_crypto_thread_num,
+        pohmelfs_opt_trans_max_pages,
+        pohmelfs_opt_crypto_fail_unsupported,
+
+        /* Remountable options */
+        pohmelfs_opt_trans_scan_timeout,
+        pohmelfs_opt_drop_scan_timeout,
+        pohmelfs_opt_wait_on_page_timeout,
+        pohmelfs_opt_trans_retries,
+        pohmelfs_opt_mcache_timeout,
+};
+
+static struct match_token pohmelfs_tokens[] = {
+        {pohmelfs_opt_idx, "idx=%u"},
+        {pohmelfs_opt_crypto_thread_num, "crypto_thread_num=%u"},
+        {pohmelfs_opt_trans_max_pages, "trans_max_pages=%u"},
+        {pohmelfs_opt_crypto_fail_unsupported, "crypto_fail_unsupported"},
+        {pohmelfs_opt_trans_scan_timeout, "trans_scan_timeout=%u"},
+        {pohmelfs_opt_drop_scan_timeout, "drop_scan_timeout=%u"},
+        {pohmelfs_opt_wait_on_page_timeout, "wait_on_page_timeout=%u"},
+        {pohmelfs_opt_trans_retries, "trans_retries=%u"},
+        {pohmelfs_opt_mcache_timeout, "mcache_timeout=%u"},
+};
+
+static int pohmelfs_parse_options(char *options, struct pohmelfs_sb *psb, int remount)
+{
+        char *p;
+        substring_t args[MAX_OPT_ARGS];
+        int option, err;
+
+        if (!options)
+                return 0;
+
+        while ((p = strsep(&options, ",")) != NULL) {
+                int token;
+                if (!*p)
+                        continue;
+
+                token = match_token(p, pohmelfs_tokens, args);
+
+                err = match_int(&args[0], &option);
+                if (err)
+                        return err;
+
+                if (remount && token <= pohmelfs_opt_crypto_fail_unsupported)
+                        continue;
+
+                switch (token) {
+                case pohmelfs_opt_idx:
+                        psb->idx = option;
+                        break;
+                case pohmelfs_opt_trans_scan_timeout:
+                        psb->trans_scan_timeout = msecs_to_jiffies(option);
+                        break;
+                case pohmelfs_opt_drop_scan_timeout:
+                        psb->drop_scan_timeout = msecs_to_jiffies(option);
+                        break;
+                case pohmelfs_opt_wait_on_page_timeout:
+                        psb->wait_on_page_timeout = msecs_to_jiffies(option);
+                        break;
+                case pohmelfs_opt_mcache_timeout:
+                        psb->mcache_timeout = msecs_to_jiffies(option);
+                        break;
+                case pohmelfs_opt_trans_retries:
+                        psb->trans_retries = option;
+                        break;
+                case pohmelfs_opt_crypto_thread_num:
+                        psb->crypto_thread_num = option;
+                        break;
+                case pohmelfs_opt_trans_max_pages:
+                        psb->trans_max_pages = option;
+                        break;
+                case pohmelfs_opt_crypto_fail_unsupported:
+                        psb->crypto_fail_unsupported = 1;
+                        break;
+                default:
+                        return -EINVAL;
+                }
+        }
+
+        return 0;
+}
+
+static int pohmelfs_remount(struct super_block *sb, int *flags, char *data)
+{
+        int err;
+        struct pohmelfs_sb *psb = POHMELFS_SB(sb);
+        unsigned long old_sb_flags = sb->s_flags;
+
+        err = pohmelfs_parse_options(data, psb, 1);
+        if (err)
+                goto err_out_restore;
+
+        if (!(*flags & MS_RDONLY))
+                sb->s_flags &= ~MS_RDONLY;
+        return 0;
+
+err_out_restore:
+        sb->s_flags = old_sb_flags;
+        return err;
+}
+
+static void pohmelfs_flush_inode(struct pohmelfs_inode *pi, unsigned int count)
+{
+        struct inode *inode = &pi->vfs_inode;
+
+        dprintk("%s: %p: ino: %llu, owned: %d.\n",
+                __func__, inode, pi->ino, test_bit(NETFS_INODE_OWNED, &pi->state));
+
+        mutex_lock(&inode->i_mutex);
+        if (test_and_clear_bit(NETFS_INODE_OWNED, &pi->state)) {
+                filemap_fdatawrite(inode->i_mapping);
+                inode->i_sb->s_op->write_inode(inode, 0);
+        }
+
+#ifdef POHMELFS_TRUNCATE_ON_INODE_FLUSH
+        truncate_inode_pages(inode->i_mapping, 0);
+#endif
+
+        pohmelfs_data_unlock(pi, 0, ~0, POHMELFS_WRITE_LOCK);
+        mutex_unlock(&inode->i_mutex);
+}
+
+static void pohmelfs_put_inode_count(struct pohmelfs_inode *pi, unsigned int count)
+{
+        dprintk("%s: ino: %llu, pi: %p, inode: %p, count: %u.\n",
+                        __func__, pi->ino, pi, &pi->vfs_inode, count);
+
+        if (test_and_clear_bit(NETFS_INODE_NEED_FLUSH, &pi->state))
+                pohmelfs_flush_inode(pi, count);
+
+        while (count--)
+                iput(&pi->vfs_inode);
+}
+
+static void pohmelfs_drop_scan(struct work_struct *work)
+{
+        struct pohmelfs_sb *psb =
+                container_of(work, struct pohmelfs_sb, drop_dwork.work);
+        struct pohmelfs_inode *pi;
+        unsigned int count = 0;
+
+        while ((pi = pohmelfs_get_inode_from_list(psb, &psb->drop_list, &count)))
+                pohmelfs_put_inode_count(pi, count);
+
+        pohmelfs_check_states(psb);
+
+        if (psb->drop_scan_timeout)
+                schedule_delayed_work(&psb->drop_dwork, psb->drop_scan_timeout);
+}
+
+/*
+ * Run through all transactions starting from the oldest,
+ * drop transaction from current state and try to send it
+ * to all remote nodes, which are currently installed.
+ */
+static void pohmelfs_trans_scan_state(struct netfs_state *st)
+{
+        struct rb_node *rb_node;
+        struct netfs_trans_dst *dst;
+        struct pohmelfs_sb *psb = st->psb;
+        unsigned int timeout = psb->trans_scan_timeout;
+        struct netfs_trans *t;
+        int err;
+
+        mutex_lock(&st->trans_lock);
+        for (rb_node = rb_first(&st->trans_root); rb_node; ) {
+                dst = rb_entry(rb_node, struct netfs_trans_dst, state_entry);
+                t = dst->trans;
+
+                if (timeout && time_after(dst->send_time + timeout, jiffies)
+                                && dst->retries == 0)
+                        break;
+
+                dprintk("%s: t: %p, gen: %u, st: %p, retries: %u, max: %u.\n",
+                        __func__, t, t->gen, st, dst->retries, psb->trans_retries);
+                netfs_trans_get(t);
+
+                rb_node = rb_next(rb_node);
+
+                err = -ETIMEDOUT;
+                if (timeout && (++dst->retries < psb->trans_retries))
+                        err = netfs_trans_resend(t, psb);
+
+                if (err || (t->flags & NETFS_TRANS_SINGLE_DST)) {
+                        if (netfs_trans_remove_nolock(dst, st))
+                                netfs_trans_drop_dst_nostate(dst);
+                }
+
+                t->result = err;
+                netfs_trans_put(t);
+        }
+        mutex_unlock(&st->trans_lock);
+}
+
+/*
+ * Walk through all installed network states and resend all
+ * transactions, which are old enough.
+ */
+static void pohmelfs_trans_scan(struct work_struct *work)
+{
+        struct pohmelfs_sb *psb =
+                container_of(work, struct pohmelfs_sb, dwork.work);
+        struct netfs_state *st;
+        struct pohmelfs_config *c;
+
+        mutex_lock(&psb->state_lock);
+        list_for_each_entry(c, &psb->state_list, config_entry) {
+                st = &c->state;
+
+                pohmelfs_trans_scan_state(st);
+        }
+        mutex_unlock(&psb->state_lock);
+
+        /*
+         * If no timeout specified then system is in the middle of umount process,
+         * so no need to reschedule scanning process again.
+         */
+        if (psb->trans_scan_timeout)
+                schedule_delayed_work(&psb->dwork, psb->trans_scan_timeout);
+}
+
+int pohmelfs_meta_command_data(struct pohmelfs_inode *pi, u64 id, unsigned int cmd_op, char *addon,
+                unsigned int flags, netfs_trans_complete_t complete, void *priv, u64 start)
+{
+        struct inode *inode = &pi->vfs_inode;
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        int err = 0, sz;
+        struct netfs_trans *t;
+        int path_len, addon_len = 0;
+        void *data;
+        struct netfs_inode_info *info;
+        struct netfs_cmd *cmd;
+
+        dprintk("%s: ino: %llu, cmd: %u, addon: %p.\n", __func__, pi->ino, cmd_op, addon);
+
+        path_len = pohmelfs_path_length(pi);
+        if (path_len < 0) {
+                err = path_len;
+                goto err_out_exit;
+        }
+
+        if (addon)
+                addon_len = strlen(addon) + 1; /* 0-byte */
+        sz = addon_len;
+
+        if (cmd_op == NETFS_INODE_INFO)
+                sz += sizeof(struct netfs_inode_info);
+
+        t = netfs_trans_alloc(psb, sz + path_len, flags, 0);
+        if (!t) {
+                err = -ENOMEM;
+                goto err_out_exit;
+        }
+        t->complete = complete;
+        t->private = priv;
+
+        cmd = netfs_trans_current(t);
+        data = (void *)(cmd + 1);
+
+        if (cmd_op == NETFS_INODE_INFO) {
+                info = (struct netfs_inode_info *)(cmd + 1);
+                data = (void *)(info + 1);
+
+                /*
+                 * We are under i_mutex, can read and change whatever we want...
+                 */
+                info->mode = inode->i_mode;
+                info->nlink = inode->i_nlink;
+                info->uid = inode->i_uid;
+                info->gid = inode->i_gid;
+                info->blocks = inode->i_blocks;
+                info->rdev = inode->i_rdev;
+                info->size = inode->i_size;
+                info->version = inode->i_version;
+
+                netfs_convert_inode_info(info);
+        }
+
+        path_len = pohmelfs_construct_path_string(pi, data, path_len);
+        if (path_len < 0)
+                goto err_out_free;
+
+        dprintk("%s: path_len: %d.\n", __func__, path_len);
+
+        if (addon) {
+                path_len--; /* Do not place null-byte before the addon */
+                path_len += sprintf(data + path_len, "/%s", addon) + 1; /* 0 - byte */
+        }
+
+        sz += path_len;
+
+        cmd->cmd = cmd_op;
+        cmd->ext = path_len;
+        cmd->size = sz;
+        cmd->id = id;
+        cmd->start = start;
+
+        netfs_convert_cmd(cmd);
+        netfs_trans_update(cmd, t, sz);
+
+        /*
+         * Note, that it is possible to leak error here: transaction callback will not
+         * be invoked for allocation path failure.
+         */
+        return netfs_trans_finish(t, psb);
+
+err_out_free:
+        netfs_trans_free(t);
+err_out_exit:
+        if (complete)
+                complete(NULL, 0, priv, err);
+        return err;
+}
+
+int pohmelfs_meta_command(struct pohmelfs_inode *pi, unsigned int cmd_op, unsigned int flags,
+                netfs_trans_complete_t complete, void *priv, u64 start)
+{
+        return pohmelfs_meta_command_data(pi, pi->ino, cmd_op, NULL, flags, complete, priv, start);
+}
+
+/*
+ * Send request and wait for POHMELFS root capabilities response,
+ * which will update server's informaion about size of the export,
+ * permissions, number of objects, available size and so on.
+ */
+static int pohmelfs_root_handshake(struct pohmelfs_sb *psb)
+{
+        struct netfs_trans *t;
+        struct netfs_cmd *cmd;
+        int err = -ENOMEM;
+
+        t = netfs_trans_alloc(psb, 0, 0, 0);
+        if (!t)
+                goto err_out_exit;
+
+        cmd = netfs_trans_current(t);
+
+        cmd->cmd = NETFS_CAPABILITIES;
+        cmd->id = POHMELFS_ROOT_CAPABILITIES;
+        cmd->size = 0;
+        cmd->start = 0;
+        cmd->ext = 0;
+        cmd->csize = 0;
+
+        netfs_convert_cmd(cmd);
+        netfs_trans_update(cmd, t, 0);
+
+        err = netfs_trans_finish(t, psb);
+        if (err)
+                goto err_out_exit;
+
+        psb->flags = ~0;
+        err = wait_event_interruptible_timeout(psb->wait,
+                        (psb->flags != ~0),
+                        psb->wait_on_page_timeout);
+        if (!err)
+                err = -ETIMEDOUT;
+        else if (err > 0)
+                err = -psb->flags;
+
+        if (err)
+                goto err_out_exit;
+
+        return 0;
+
+err_out_exit:
+        return err;
+}
+
+static int pohmelfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
+{
+        struct netfs_state *st;
+        struct pohmelfs_ctl *ctl;
+        struct pohmelfs_sb *psb = POHMELFS_SB(mnt->mnt_sb);
+        struct pohmelfs_config *c;
+
+        mutex_lock(&psb->state_lock);
+
+        seq_printf(m, "\nidx addr(:port) socket_type protocol active priority permissions\n");
+
+        list_for_each_entry(c, &psb->state_list, config_entry) {
+                st = &c->state;
+                ctl = &st->ctl;
+
+                seq_printf(m, "%u ", ctl->idx);
+                if (ctl->addr.sa_family == AF_INET) {
+                        struct sockaddr_in *sin = (struct sockaddr_in *)&st->ctl.addr;
+                        seq_printf(m, "%pI4:%u", &sin->sin_addr.s_addr, ntohs(sin->sin_port));
+                } else if (ctl->addr.sa_family == AF_INET6) {
+                        struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&st->ctl.addr;
+                        seq_printf(m, "%pi6:%u", &sin->sin6_addr, ntohs(sin->sin6_port));
+                } else {
+                        unsigned int i;
+                        for (i = 0; i < ctl->addrlen; ++i)
+                                seq_printf(m, "%02x.", ctl->addr.addr[i]);
+                }
+
+                seq_printf(m, " %u %u %d %u %x\n",
+                                ctl->type, ctl->proto,
+                                st->socket != NULL,
+                                ctl->prio, ctl->perm);
+        }
+        mutex_unlock(&psb->state_lock);
+
+        return 0;
+}
+
+static const struct super_operations pohmelfs_sb_ops = {
+        .alloc_inode    = pohmelfs_alloc_inode,
+        .destroy_inode  = pohmelfs_destroy_inode,
+        .drop_inode     = pohmelfs_drop_inode,
+        .write_inode    = pohmelfs_write_inode,
+        .put_super      = pohmelfs_put_super,
+        .remount_fs     = pohmelfs_remount,
+        .statfs         = pohmelfs_statfs,
+        .show_options   = pohmelfs_show_options,
+        .show_stats     = pohmelfs_show_stats,
+};
+
+/*
+ * Allocate private superblock and create root dir.
+ */
+static int pohmelfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+        struct pohmelfs_sb *psb;
+        int err = -ENOMEM;
+        struct inode *root;
+        struct pohmelfs_inode *npi;
+        struct qstr str;
+
+        psb = kzalloc(sizeof(struct pohmelfs_sb), GFP_KERNEL);
+        if (!psb)
+                goto err_out_exit;
+
+        err = bdi_init(&psb->bdi);
+        if (err)
+                goto err_out_free_sb;
+
+        err = bdi_register(&psb->bdi, NULL, "pfs-%d", atomic_inc_return(&psb_bdi_num));
+        if (err) {
+                bdi_destroy(&psb->bdi);
+                goto err_out_free_sb;
+        }
+
+        sb->s_fs_info = psb;
+        sb->s_op = &pohmelfs_sb_ops;
+        sb->s_magic = POHMELFS_MAGIC_NUM;
+        sb->s_maxbytes = MAX_LFS_FILESIZE;
+        sb->s_blocksize = PAGE_SIZE;
+        sb->s_bdi = &psb->bdi;
+
+        psb->sb = sb;
+
+        psb->ino = 2;
+        psb->idx = 0;
+        psb->active_state = NULL;
+        psb->trans_retries = 5;
+        psb->trans_data_size = PAGE_SIZE;
+        psb->drop_scan_timeout = msecs_to_jiffies(1000);
+        psb->trans_scan_timeout = msecs_to_jiffies(5000);
+        psb->wait_on_page_timeout = msecs_to_jiffies(5000);
+        init_waitqueue_head(&psb->wait);
+
+        spin_lock_init(&psb->ino_lock);
+
+        INIT_LIST_HEAD(&psb->drop_list);
+
+        mutex_init(&psb->mcache_lock);
+        psb->mcache_root = RB_ROOT;
+        psb->mcache_timeout = msecs_to_jiffies(5000);
+        atomic_long_set(&psb->mcache_gen, 0);
+
+        psb->trans_max_pages = 100;
+
+        psb->crypto_align_size = 16;
+        psb->crypto_attached_size = 0;
+        psb->hash_strlen = 0;
+        psb->cipher_strlen = 0;
+        psb->perform_crypto = 0;
+        psb->crypto_thread_num = 2;
+        psb->crypto_fail_unsupported = 0;
+        mutex_init(&psb->crypto_thread_lock);
+        INIT_LIST_HEAD(&psb->crypto_ready_list);
+        INIT_LIST_HEAD(&psb->crypto_active_list);
+
+        atomic_set(&psb->trans_gen, 1);
+        atomic_long_set(&psb->total_inodes, 0);
+
+        mutex_init(&psb->state_lock);
+        INIT_LIST_HEAD(&psb->state_list);
+
+        err = pohmelfs_parse_options((char *) data, psb, 0);
+        if (err)
+                goto err_out_free_bdi;
+
+        err = pohmelfs_copy_crypto(psb);
+        if (err)
+                goto err_out_free_bdi;
+
+        err = pohmelfs_state_init(psb);
+        if (err)
+                goto err_out_free_strings;
+
+        err = pohmelfs_crypto_init(psb);
+        if (err)
+                goto err_out_state_exit;
+
+        err = pohmelfs_root_handshake(psb);
+        if (err)
+                goto err_out_crypto_exit;
+
+        str.name = "/";
+        str.hash = jhash("/", 1, 0);
+        str.len = 1;
+
+        npi = pohmelfs_create_entry_local(psb, NULL, &str, 0, 0755|S_IFDIR);
+        if (IS_ERR(npi)) {
+                err = PTR_ERR(npi);
+                goto err_out_crypto_exit;
+        }
+        set_bit(NETFS_INODE_REMOTE_SYNCED, &npi->state);
+        clear_bit(NETFS_INODE_OWNED, &npi->state);
+
+        root = &npi->vfs_inode;
+
+        sb->s_root = d_alloc_root(root);
+        if (!sb->s_root)
+                goto err_out_put_root;
+
+        INIT_DELAYED_WORK(&psb->drop_dwork, pohmelfs_drop_scan);
+        schedule_delayed_work(&psb->drop_dwork, psb->drop_scan_timeout);
+
+        INIT_DELAYED_WORK(&psb->dwork, pohmelfs_trans_scan);
+        schedule_delayed_work(&psb->dwork, psb->trans_scan_timeout);
+
+        return 0;
+
+err_out_put_root:
+        iput(root);
+err_out_crypto_exit:
+        pohmelfs_crypto_exit(psb);
+err_out_state_exit:
+        pohmelfs_state_exit(psb);
+err_out_free_strings:
+        kfree(psb->cipher_string);
+        kfree(psb->hash_string);
+err_out_free_bdi:
+        bdi_destroy(&psb->bdi);
+err_out_free_sb:
+        kfree(psb);
+err_out_exit:
+
+        dprintk("%s: err: %d.\n", __func__, err);
+        return err;
+}
+
+/*
+ * Some VFS magic here...
+ */
+static struct dentry *pohmelfs_mount(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *data)
+{
+        return mount_nodev(fs_type, flags, data, pohmelfs_fill_super);
+}
+
+/*
+ * We need this to sync all inodes earlier, since when writeback
+ * is invoked from the umount/mntput path dcache is already shrunk,
+ * see generic_shutdown_super(), and no inodes can access the path.
+ */
+static void pohmelfs_kill_super(struct super_block *sb)
+{
+        sync_inodes_sb(sb);
+        kill_anon_super(sb);
+}
+
+static struct file_system_type pohmel_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "pohmel",
+        .mount          = pohmelfs_mount,
+        .kill_sb        = pohmelfs_kill_super,
+};
+
+/*
+ * Cache and module initializations and freeing routings.
+ */
+static void pohmelfs_init_once(void *data)
+{
+        struct pohmelfs_inode *pi = data;
+
+        inode_init_once(&pi->vfs_inode);
+}
+
+static int __init pohmelfs_init_inodecache(void)
+{
+        pohmelfs_inode_cache = kmem_cache_create("pohmelfs_inode_cache",
+                                sizeof(struct pohmelfs_inode),
+                                0, (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD),
+                                pohmelfs_init_once);
+        if (!pohmelfs_inode_cache)
+                return -ENOMEM;
+
+        return 0;
+}
+
+static void pohmelfs_destroy_inodecache(void)
+{
+        kmem_cache_destroy(pohmelfs_inode_cache);
+}
+
+static int __init init_pohmel_fs(void)
+{
+        int err;
+
+        err = pohmelfs_config_init();
+        if (err)
+                goto err_out_exit;
+
+        err = pohmelfs_init_inodecache();
+        if (err)
+                goto err_out_config_exit;
+
+        err = pohmelfs_mcache_init();
+        if (err)
+                goto err_out_destroy;
+
+        err = netfs_trans_init();
+        if (err)
+                goto err_out_mcache_exit;
+
+        err = register_filesystem(&pohmel_fs_type);
+        if (err)
+                goto err_out_trans;
+
+        return 0;
+
+err_out_trans:
+        netfs_trans_exit();
+err_out_mcache_exit:
+        pohmelfs_mcache_exit();
+err_out_destroy:
+        pohmelfs_destroy_inodecache();
+err_out_config_exit:
+        pohmelfs_config_exit();
+err_out_exit:
+        return err;
+}
+
+static void __exit exit_pohmel_fs(void)
+{
+        unregister_filesystem(&pohmel_fs_type);
+        pohmelfs_destroy_inodecache();
+        pohmelfs_mcache_exit();
+        pohmelfs_config_exit();
+        netfs_trans_exit();
+}
+
+module_init(init_pohmel_fs);
+module_exit(exit_pohmel_fs);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
+MODULE_DESCRIPTION("Pohmel filesystem");
diff --git a/drivers/staging/pohmelfs/lock.c b/drivers/staging/pohmelfs/lock.c
new file mode 100644
index 00000000000..6710114cd42
--- /dev/null
+++ b/drivers/staging/pohmelfs/lock.c
@@ -0,0 +1,182 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/backing-dev.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/mempool.h>
+
+#include "netfs.h"
+
+static int pohmelfs_send_lock_trans(struct pohmelfs_inode *pi,
+                u64 id, u64 start, u32 size, int type)
+{
+        struct inode *inode = &pi->vfs_inode;
+        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
+        struct netfs_trans *t;
+        struct netfs_cmd *cmd;
+        int path_len, err;
+        void *data;
+        struct netfs_lock *l;
+        int isize = (type & POHMELFS_LOCK_GRAB) ? 0 : sizeof(struct netfs_inode_info);
+
+        err = pohmelfs_path_length(pi);
+        if (err < 0)
+                goto err_out_exit;
+
+        path_len = err;
+
+        err = -ENOMEM;
+        t = netfs_trans_alloc(psb, path_len + sizeof(struct netfs_lock) + isize,
+                        NETFS_TRANS_SINGLE_DST, 0);
+        if (!t)
+                goto err_out_exit;
+
+        cmd = netfs_trans_current(t);
+        data = cmd + 1;
+
+        err = pohmelfs_construct_path_string(pi, data, path_len);
+        if (err < 0)
+                goto err_out_free;
+        path_len = err;
+
+        l = data + path_len;
+
+        l->start = start;
+        l->size = size;
+        l->type = type;
+        l->ino = pi->ino;
+
+        cmd->cmd = NETFS_LOCK;
+        cmd->start = 0;
+        cmd->id = id;
+        cmd->size = sizeof(struct netfs_lock) + path_len + isize;
+        cmd->ext = path_len;
+        cmd->csize = 0;
+
+        netfs_convert_cmd(cmd);
+        netfs_convert_lock(l);
+
+        if (isize) {
+                struct netfs_inode_info *info = (struct netfs_inode_info *)(l + 1);
+
+                info->mode = inode->i_mode;
+                info->nlink = inode->i_nlink;
+                info->uid = inode->i_uid;
+                info->gid = inode->i_gid;
+                info->blocks = inode->i_blocks;
+                info->rdev = inode->i_rdev;
+                info->size = inode->i_size;
+                info->version = inode->i_version;
+
+                netfs_convert_inode_info(info);
+        }
+
+        netfs_trans_update(cmd, t, path_len + sizeof(struct netfs_lock) + isize);
+
+        return netfs_trans_finish(t, psb);
+
+err_out_free:
+        netfs_trans_free(t);
+err_out_exit:
+        printk("%s: err: %d.\n", __func__, err);
+        return err;
+}
+
+int pohmelfs_data_lock(struct pohmelfs_inode *pi, u64 start, u32 size, int type)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
+        struct pohmelfs_mcache *m;
+        int err = -ENOMEM;
+        struct iattr iattr;
+        struct inode *inode = &pi->vfs_inode;
+
+        dprintk("%s: %p: ino: %llu, start: %llu, size: %u, "
+                        "type: %d, locked as: %d, owned: %d.\n",
+                        __func__, &pi->vfs_inode, pi->ino,
+                        start, size, type, pi->lock_type,
+                        !!test_bit(NETFS_INODE_OWNED, &pi->state));
+
+        if (!pohmelfs_need_lock(pi, type))
+                return 0;
+
+        m = pohmelfs_mcache_alloc(psb, start, size, NULL);
+        if (IS_ERR(m))
+                return PTR_ERR(m);
+
+        err = pohmelfs_send_lock_trans(pi, m->gen, start, size,
+                        type | POHMELFS_LOCK_GRAB);
+        if (err)
+                goto err_out_put;
+
+        err = wait_for_completion_timeout(&m->complete, psb->mcache_timeout);
+        if (err)
+                err = m->err;
+        else
+                err = -ETIMEDOUT;
+
+        if (err) {
+                printk("%s: %p: ino: %llu, mgen: %llu, start: %llu, size: %u, err: %d.\n",
+                        __func__, &pi->vfs_inode, pi->ino, m->gen, start, size, err);
+        }
+
+        if (err && (err != -ENOENT))
+                goto err_out_put;
+
+        if (!err) {
+                netfs_convert_inode_info(&m->info);
+
+                iattr.ia_valid = ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_SIZE | ATTR_ATIME;
+                iattr.ia_mode = m->info.mode;
+                iattr.ia_uid = m->info.uid;
+                iattr.ia_gid = m->info.gid;
+                iattr.ia_size = m->info.size;
+                iattr.ia_atime = CURRENT_TIME;
+
+                dprintk("%s: %p: ino: %llu, mgen: %llu, start: %llu, isize: %llu -> %llu.\n",
+                        __func__, &pi->vfs_inode, pi->ino, m->gen, start, inode->i_size, m->info.size);
+
+                err = pohmelfs_setattr_raw(inode, &iattr);
+                if (!err) {
+                        struct dentry *dentry = d_find_alias(inode);
+                        if (dentry) {
+                                fsnotify_change(dentry, iattr.ia_valid);
+                                dput(dentry);
+                        }
+                }
+        }
+
+        pi->lock_type = type;
+        set_bit(NETFS_INODE_OWNED, &pi->state);
+
+        pohmelfs_mcache_put(psb, m);
+
+        return 0;
+
+err_out_put:
+        pohmelfs_mcache_put(psb, m);
+        return err;
+}
+
+int pohmelfs_data_unlock(struct pohmelfs_inode *pi, u64 start, u32 size, int type)
+{
+        dprintk("%s: %p: ino: %llu, start: %llu, size: %u, type: %d.\n",
+                        __func__, &pi->vfs_inode, pi->ino, start, size, type);
+        pi->lock_type = 0;
+        clear_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &pi->state);
+        clear_bit(NETFS_INODE_OWNED, &pi->state);
+        return pohmelfs_send_lock_trans(pi, pi->ino, start, size, type);
+}
diff --git a/drivers/staging/pohmelfs/mcache.c b/drivers/staging/pohmelfs/mcache.c
new file mode 100644
index 00000000000..e22665cdd16
--- /dev/null
+++ b/drivers/staging/pohmelfs/mcache.c
@@ -0,0 +1,171 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/mempool.h>
+
+#include "netfs.h"
+
+static struct kmem_cache *pohmelfs_mcache_cache;
+static mempool_t *pohmelfs_mcache_pool;
+
+static inline int pohmelfs_mcache_cmp(u64 gen, u64 new)
+{
+        if (gen < new)
+                return 1;
+        if (gen > new)
+                return -1;
+        return 0;
+}
+
+struct pohmelfs_mcache *pohmelfs_mcache_search(struct pohmelfs_sb *psb, u64 gen)
+{
+        struct rb_root *root = &psb->mcache_root;
+        struct rb_node *n = root->rb_node;
+        struct pohmelfs_mcache *tmp, *ret = NULL;
+        int cmp;
+
+        while (n) {
+                tmp = rb_entry(n, struct pohmelfs_mcache, mcache_entry);
+
+                cmp = pohmelfs_mcache_cmp(tmp->gen, gen);
+                if (cmp < 0)
+                        n = n->rb_left;
+                else if (cmp > 0)
+                        n = n->rb_right;
+                else {
+                        ret = tmp;
+                        pohmelfs_mcache_get(ret);
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+static int pohmelfs_mcache_insert(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
+{
+        struct rb_root *root = &psb->mcache_root;
+        struct rb_node **n = &root->rb_node, *parent = NULL;
+        struct pohmelfs_mcache *ret = NULL, *tmp;
+        int cmp;
+
+        while (*n) {
+                parent = *n;
+
+                tmp = rb_entry(parent, struct pohmelfs_mcache, mcache_entry);
+
+                cmp = pohmelfs_mcache_cmp(tmp->gen, m->gen);
+                if (cmp < 0)
+                        n = &parent->rb_left;
+                else if (cmp > 0)
+                        n = &parent->rb_right;
+                else {
+                        ret = tmp;
+                        break;
+                }
+        }
+
+        if (ret)
+                return -EEXIST;
+
+        rb_link_node(&m->mcache_entry, parent, n);
+        rb_insert_color(&m->mcache_entry, root);
+
+        return 0;
+}
+
+static int pohmelfs_mcache_remove(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
+{
+        if (m && m->mcache_entry.rb_parent_color) {
+                rb_erase(&m->mcache_entry, &psb->mcache_root);
+                m->mcache_entry.rb_parent_color = 0;
+                return 1;
+        }
+        return 0;
+}
+
+void pohmelfs_mcache_remove_locked(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
+{
+        mutex_lock(&psb->mcache_lock);
+        pohmelfs_mcache_remove(psb, m);
+        mutex_unlock(&psb->mcache_lock);
+}
+
+struct pohmelfs_mcache *pohmelfs_mcache_alloc(struct pohmelfs_sb *psb, u64 start,
+                unsigned int size, void *data)
+{
+        struct pohmelfs_mcache *m;
+        int err = -ENOMEM;
+
+        m = mempool_alloc(pohmelfs_mcache_pool, GFP_KERNEL);
+        if (!m)
+                goto err_out_exit;
+
+        init_completion(&m->complete);
+        m->err = 0;
+        atomic_set(&m->refcnt, 1);
+        m->data = data;
+        m->start = start;
+        m->size = size;
+        m->gen = atomic_long_inc_return(&psb->mcache_gen);
+
+        mutex_lock(&psb->mcache_lock);
+        err = pohmelfs_mcache_insert(psb, m);
+        mutex_unlock(&psb->mcache_lock);
+        if (err)
+                goto err_out_free;
+
+        return m;
+
+err_out_free:
+        mempool_free(m, pohmelfs_mcache_pool);
+err_out_exit:
+        return ERR_PTR(err);
+}
+
+void pohmelfs_mcache_free(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m)
+{
+        pohmelfs_mcache_remove_locked(psb, m);
+
+        mempool_free(m, pohmelfs_mcache_pool);
+}
+
+int __init pohmelfs_mcache_init(void)
+{
+        pohmelfs_mcache_cache = kmem_cache_create("pohmelfs_mcache_cache",
+                                sizeof(struct pohmelfs_mcache),
+                                0, (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD), NULL);
+        if (!pohmelfs_mcache_cache)
+                goto err_out_exit;
+
+        pohmelfs_mcache_pool = mempool_create_slab_pool(256, pohmelfs_mcache_cache);
+        if (!pohmelfs_mcache_pool)
+                goto err_out_free;
+
+        return 0;
+
+err_out_free:
+        kmem_cache_destroy(pohmelfs_mcache_cache);
+err_out_exit:
+        return -ENOMEM;
+}
+
+void pohmelfs_mcache_exit(void)
+{
+        mempool_destroy(pohmelfs_mcache_pool);
+        kmem_cache_destroy(pohmelfs_mcache_cache);
+}
diff --git a/drivers/staging/pohmelfs/net.c b/drivers/staging/pohmelfs/net.c
new file mode 100644
index 00000000000..b2e91862208
--- /dev/null
+++ b/drivers/staging/pohmelfs/net.c
@@ -0,0 +1,1209 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/fsnotify.h>
+#include <linux/jhash.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/kthread.h>
+#include <linux/pagemap.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+#include <linux/vmalloc.h>
+
+#include "netfs.h"
+
+/*
+ * Async machinery lives here.
+ * All commands being sent to server do _not_ require sync reply,
+ * instead, if it is really needed, like readdir or readpage, caller
+ * sleeps waiting for data, which will be placed into provided buffer
+ * and caller will be awakened.
+ *
+ * Every command response can come without some listener. For example
+ * readdir response will add new objects into cache without appropriate
+ * request from userspace. This is used in cache coherency.
+ *
+ * If object is not found for given data, it is discarded.
+ *
+ * All requests are received by dedicated kernel thread.
+ */
+
+/*
+ * Basic network sending/receiving functions.
+ * Blocked mode is used.
+ */
+static int netfs_data_recv(struct netfs_state *st, void *buf, u64 size)
+{
+        struct msghdr msg;
+        struct kvec iov;
+        int err;
+
+        BUG_ON(!size);
+
+        iov.iov_base = buf;
+        iov.iov_len = size;
+
+        msg.msg_iov = (struct iovec *)&iov;
+        msg.msg_iovlen = 1;
+        msg.msg_name = NULL;
+        msg.msg_namelen = 0;
+        msg.msg_control = NULL;
+        msg.msg_controllen = 0;
+        msg.msg_flags = MSG_DONTWAIT;
+
+        err = kernel_recvmsg(st->socket, &msg, &iov, 1, iov.iov_len,
+                        msg.msg_flags);
+        if (err <= 0) {
+                printk("%s: failed to recv data: size: %llu, err: %d.\n", __func__, size, err);
+                if (err == 0)
+                        err = -ECONNRESET;
+        }
+
+        return err;
+}
+
+static int pohmelfs_data_recv(struct netfs_state *st, void *data, unsigned int size)
+{
+        unsigned int revents = 0;
+        unsigned int err_mask = POLLERR | POLLHUP | POLLRDHUP;
+        unsigned int mask = err_mask | POLLIN;
+        int err = 0;
+
+        while (size && !err) {
+                revents = netfs_state_poll(st);
+
+                if (!(revents & mask)) {
+                        DEFINE_WAIT(wait);
+
+                        for (;;) {
+                                prepare_to_wait(&st->thread_wait, &wait, TASK_INTERRUPTIBLE);
+                                if (kthread_should_stop())
+                                        break;
+
+                                revents = netfs_state_poll(st);
+
+                                if (revents & mask)
+                                        break;
+
+                                if (signal_pending(current))
+                                        break;
+
+                                schedule();
+                                continue;
+                        }
+                        finish_wait(&st->thread_wait, &wait);
+                }
+
+                err = 0;
+                netfs_state_lock(st);
+                if (st->socket && (st->read_socket == st->socket) && (revents & POLLIN)) {
+                        err = netfs_data_recv(st, data, size);
+                        if (err > 0) {
+                                data += err;
+                                size -= err;
+                                err = 0;
+                        } else if (err == 0)
+                                err = -ECONNRESET;
+                }
+
+                if (revents & err_mask) {
+                        printk("%s: revents: %x, socket: %p, size: %u, err: %d.\n",
+                                        __func__, revents, st->socket, size, err);
+                        err = -ECONNRESET;
+                }
+                netfs_state_unlock(st);
+
+                if (err < 0) {
+                        if (netfs_state_trylock_send(st)) {
+                                netfs_state_exit(st);
+                                err = netfs_state_init(st);
+                                if (!err)
+                                        err = -EAGAIN;
+                                netfs_state_unlock_send(st);
+                        } else {
+                                st->need_reset = 1;
+                        }
+                }
+
+                if (kthread_should_stop())
+                        err = -ENODEV;
+
+                if (err)
+                        printk("%s: socket: %p, read_socket: %p, revents: %x, rev_error: %d, "
+                                        "should_stop: %d, size: %u, err: %d.\n",
+                                __func__, st->socket, st->read_socket,
+                                revents, revents & err_mask, kthread_should_stop(), size, err);
+        }
+
+        return err;
+}
+
+int pohmelfs_data_recv_and_check(struct netfs_state *st, void *data, unsigned int size)
+{
+        struct netfs_cmd *cmd = &st->cmd;
+        int err;
+
+        err = pohmelfs_data_recv(st, data, size);
+        if (err)
+                return err;
+
+        return pohmelfs_crypto_process_input_data(&st->eng, cmd->iv, data, NULL, size);
+}
+
+/*
+ * Polling machinery.
+ */
+
+struct netfs_poll_helper {
+        poll_table              pt;
+        struct netfs_state      *st;
+};
+
+static int netfs_queue_wake(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+        struct netfs_state *st = container_of(wait, struct netfs_state, wait);
+
+        wake_up(&st->thread_wait);
+        return 1;
+}
+
+static void netfs_queue_func(struct file *file, wait_queue_head_t *whead,
+                                 poll_table *pt)
+{
+        struct netfs_state *st = container_of(pt, struct netfs_poll_helper, pt)->st;
+
+        st->whead = whead;
+        init_waitqueue_func_entry(&st->wait, netfs_queue_wake);
+        add_wait_queue(whead, &st->wait);
+}
+
+static void netfs_poll_exit(struct netfs_state *st)
+{
+        if (st->whead) {
+                remove_wait_queue(st->whead, &st->wait);
+                st->whead = NULL;
+        }
+}
+
+static int netfs_poll_init(struct netfs_state *st)
+{
+        struct netfs_poll_helper ph;
+
+        ph.st = st;
+        init_poll_funcptr(&ph.pt, &netfs_queue_func);
+
+        st->socket->ops->poll(NULL, st->socket, &ph.pt);
+        return 0;
+}
+
+/*
+ * Get response for readpage command. We search inode and page in its mapping
+ * and copy data into. If it was async request, then we queue page into shared
+ * data and wakeup listener, who will copy it to userspace.
+ *
+ * There is a work in progress of allowing to call copy_to_user() directly from
+ * async receiving kernel thread.
+ */
+static int pohmelfs_read_page_response(struct netfs_state *st)
+{
+        struct pohmelfs_sb *psb = st->psb;
+        struct netfs_cmd *cmd = &st->cmd;
+        struct inode *inode;
+        struct page *page;
+        int err = 0;
+
+        if (cmd->size > PAGE_CACHE_SIZE) {
+                err = -EINVAL;
+                goto err_out_exit;
+        }
+
+        inode = ilookup(st->psb->sb, cmd->id);
+        if (!inode) {
+                printk("%s: failed to find inode: id: %llu.\n", __func__, cmd->id);
+                err = -ENOENT;
+                goto err_out_exit;
+        }
+
+        page = find_get_page(inode->i_mapping, cmd->start >> PAGE_CACHE_SHIFT);
+        if (!page || !PageLocked(page)) {
+                printk("%s: failed to find/lock page: page: %p, id: %llu, start: %llu, index: %llu.\n",
+                                __func__, page, cmd->id, cmd->start, cmd->start >> PAGE_CACHE_SHIFT);
+
+                while (cmd->size) {
+                        unsigned int sz = min(cmd->size, st->size);
+
+                        err = pohmelfs_data_recv(st, st->data, sz);
+                        if (err)
+                                break;
+
+                        cmd->size -= sz;
+                }
+
+                err = -ENODEV;
+                if (page)
+                        goto err_out_page_put;
+                goto err_out_put;
+        }
+
+        if (cmd->size) {
+                void *addr;
+
+                addr = kmap(page);
+                err = pohmelfs_data_recv(st, addr, cmd->size);
+                kunmap(page);
+
+                if (err)
+                        goto err_out_page_unlock;
+        }
+
+        dprintk("%s: page: %p, start: %llu, size: %u, locked: %d.\n",
+                __func__, page, cmd->start, cmd->size, PageLocked(page));
+
+        SetPageChecked(page);
+        if ((psb->hash_string || psb->cipher_string) && psb->perform_crypto && cmd->size) {
+                err = pohmelfs_crypto_process_input_page(&st->eng, page, cmd->size, cmd->iv);
+                if (err < 0)
+                        goto err_out_page_unlock;
+        } else {
+                SetPageUptodate(page);
+                unlock_page(page);
+                page_cache_release(page);
+        }
+
+        pohmelfs_put_inode(POHMELFS_I(inode));
+        wake_up(&st->psb->wait);
+
+        return 0;
+
+err_out_page_unlock:
+        SetPageError(page);
+        unlock_page(page);
+err_out_page_put:
+        page_cache_release(page);
+err_out_put:
+        pohmelfs_put_inode(POHMELFS_I(inode));
+err_out_exit:
+        wake_up(&st->psb->wait);
+        return err;
+}
+
+static int pohmelfs_check_name(struct pohmelfs_inode *parent, struct qstr *str,
+                struct netfs_inode_info *info)
+{
+        struct inode *inode;
+        struct pohmelfs_name *n;
+        int err = 0;
+        u64 ino = 0;
+
+        mutex_lock(&parent->offset_lock);
+        n = pohmelfs_search_hash(parent, str->hash);
+        if (n)
+                ino = n->ino;
+        mutex_unlock(&parent->offset_lock);
+
+        if (!ino)
+                goto out;
+
+        inode = ilookup(parent->vfs_inode.i_sb, ino);
+        if (!inode)
+                goto out;
+
+        dprintk("%s: parent: %llu, inode: %llu.\n", __func__, parent->ino, ino);
+
+        pohmelfs_fill_inode(inode, info);
+        pohmelfs_put_inode(POHMELFS_I(inode));
+        err = -EEXIST;
+out:
+        return err;
+}
+
+/*
+ * Readdir response from server. If special field is set, we wakeup
+ * listener (readdir() call), which will copy data to userspace.
+ */
+static int pohmelfs_readdir_response(struct netfs_state *st)
+{
+        struct inode *inode;
+        struct netfs_cmd *cmd = &st->cmd;
+        struct netfs_inode_info *info;
+        struct pohmelfs_inode *parent = NULL, *npi;
+        int err = 0, last = cmd->ext;
+        struct qstr str;
+
+        if (cmd->size > st->size)
+                return -EINVAL;
+
+        inode = ilookup(st->psb->sb, cmd->id);
+        if (!inode) {
+                printk("%s: failed to find inode: id: %llu.\n", __func__, cmd->id);
+                return -ENOENT;
+        }
+        parent = POHMELFS_I(inode);
+
+        if (!cmd->size && cmd->start) {
+                err = -cmd->start;
+                goto out;
+        }
+
+        if (cmd->size) {
+                char *name;
+
+                err = pohmelfs_data_recv_and_check(st, st->data, cmd->size);
+                if (err)
+                        goto err_out_put;
+
+                info = (struct netfs_inode_info *)(st->data);
+
+                name = (char *)(info + 1);
+                str.len = cmd->size - sizeof(struct netfs_inode_info) - 1 - cmd->cpad;
+                name[str.len] = 0;
+                str.name = name;
+                str.hash = jhash(str.name, str.len, 0);
+
+                netfs_convert_inode_info(info);
+
+                if (parent) {
+                        err = pohmelfs_check_name(parent, &str, info);
+                        if (err) {
+                                if (err == -EEXIST)
+                                        err = 0;
+                                goto out;
+                        }
+                }
+
+                info->ino = cmd->start;
+                if (!info->ino)
+                        info->ino = pohmelfs_new_ino(st->psb);
+
+                dprintk("%s: parent: %llu, ino: %llu, name: '%s', hash: %x, len: %u, mode: %o.\n",
+                                __func__, parent->ino, info->ino, str.name, str.hash, str.len,
+                                info->mode);
+
+                npi = pohmelfs_new_inode(st->psb, parent, &str, info, 0);
+                if (IS_ERR(npi)) {
+                        err = PTR_ERR(npi);
+
+                        if (err != -EEXIST)
+                                goto err_out_put;
+                } else {
+                        struct dentry *dentry, *alias, *pd;
+
+                        set_bit(NETFS_INODE_REMOTE_SYNCED, &npi->state);
+                        clear_bit(NETFS_INODE_OWNED, &npi->state);
+
+                        pd = d_find_alias(&parent->vfs_inode);
+                        if (pd) {
+                                str.hash = full_name_hash(str.name, str.len);
+                                dentry = d_alloc(pd, &str);
+                                if (dentry) {
+                                        alias = d_materialise_unique(dentry, &npi->vfs_inode);
+                                        if (alias)
+                                                dput(alias);
+                                }
+
+                                dput(dentry);
+                                dput(pd);
+                        }
+                }
+        }
+out:
+        if (last) {
+                set_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &parent->state);
+                set_bit(NETFS_INODE_REMOTE_SYNCED, &parent->state);
+                wake_up(&st->psb->wait);
+        }
+        pohmelfs_put_inode(parent);
+
+        return err;
+
+err_out_put:
+        clear_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &parent->state);
+        printk("%s: parent: %llu, ino: %llu, cmd_id: %llu.\n", __func__, parent->ino, cmd->start, cmd->id);
+        pohmelfs_put_inode(parent);
+        wake_up(&st->psb->wait);
+        return err;
+}
+
+/*
+ * Lookup command response.
+ * It searches for inode to be looked at (if it exists) and substitutes
+ * its inode information (size, permission, mode and so on), if inode does
+ * not exist, new one will be created and inserted into caches.
+ */
+static int pohmelfs_lookup_response(struct netfs_state *st)
+{
+        struct inode *inode = NULL;
+        struct netfs_cmd *cmd = &st->cmd;
+        struct netfs_inode_info *info;
+        struct pohmelfs_inode *parent = NULL, *npi;
+        int err = -EINVAL;
+        char *name;
+
+        inode = ilookup(st->psb->sb, cmd->id);
+        if (!inode) {
+                printk("%s: lookup response: id: %llu, start: %llu, size: %u.\n",
+                                __func__, cmd->id, cmd->start, cmd->size);
+                err = -ENOENT;
+                goto err_out_exit;
+        }
+        parent = POHMELFS_I(inode);
+
+        if (!cmd->size) {
+                err = -cmd->start;
+                goto err_out_put;
+        }
+
+        if (cmd->size < sizeof(struct netfs_inode_info)) {
+                printk("%s: broken lookup response: id: %llu, start: %llu, size: %u.\n",
+                                __func__, cmd->id, cmd->start, cmd->size);
+                err = -EINVAL;
+                goto err_out_put;
+        }
+
+        err = pohmelfs_data_recv_and_check(st, st->data, cmd->size);
+        if (err)
+                goto err_out_put;
+
+        info = (struct netfs_inode_info *)(st->data);
+        name = (char *)(info + 1);
+
+        netfs_convert_inode_info(info);
+
+        info->ino = cmd->start;
+        if (!info->ino)
+                info->ino = pohmelfs_new_ino(st->psb);
+
+        dprintk("%s: parent: %llu, ino: %llu, name: '%s', start: %llu.\n",
+                        __func__, parent->ino, info->ino, name, cmd->start);
+
+        if (cmd->start)
+                npi = pohmelfs_new_inode(st->psb, parent, NULL, info, 0);
+        else {
+                struct qstr str;
+
+                str.name = name;
+                str.len = cmd->size - sizeof(struct netfs_inode_info) - 1 - cmd->cpad;
+                str.hash = jhash(name, str.len, 0);
+
+                npi = pohmelfs_new_inode(st->psb, parent, &str, info, 0);
+        }
+        if (IS_ERR(npi)) {
+                err = PTR_ERR(npi);
+
+                if (err != -EEXIST)
+                        goto err_out_put;
+        } else {
+                set_bit(NETFS_INODE_REMOTE_SYNCED, &npi->state);
+                clear_bit(NETFS_INODE_OWNED, &npi->state);
+        }
+
+        clear_bit(NETFS_COMMAND_PENDING, &parent->state);
+        pohmelfs_put_inode(parent);
+
+        wake_up(&st->psb->wait);
+
+        return 0;
+
+err_out_put:
+        pohmelfs_put_inode(parent);
+err_out_exit:
+        clear_bit(NETFS_COMMAND_PENDING, &parent->state);
+        wake_up(&st->psb->wait);
+        printk("%s: inode: %p, id: %llu, start: %llu, size: %u, err: %d.\n",
+                        __func__, inode, cmd->id, cmd->start, cmd->size, err);
+        return err;
+}
+
+/*
+ * Create response, just marks local inode as 'created', so that writeback
+ * for any of its children (or own) would not try to sync it again.
+ */
+static int pohmelfs_create_response(struct netfs_state *st)
+{
+        struct inode *inode;
+        struct netfs_cmd *cmd = &st->cmd;
+        struct pohmelfs_inode *pi;
+
+        inode = ilookup(st->psb->sb, cmd->id);
+        if (!inode) {
+                printk("%s: failed to find inode: id: %llu, start: %llu.\n",
+                                __func__, cmd->id, cmd->start);
+                goto err_out_exit;
+        }
+
+        pi = POHMELFS_I(inode);
+
+        /*
+         * To lock or not to lock?
+         * We actually do not care if it races...
+         */
+        if (cmd->start)
+                make_bad_inode(inode);
+        set_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);
+
+        pohmelfs_put_inode(pi);
+
+        wake_up(&st->psb->wait);
+        return 0;
+
+err_out_exit:
+        wake_up(&st->psb->wait);
+        return -ENOENT;
+}
+
+/*
+ * Object remove response. Just says that remove request has been received.
+ * Used in cache coherency protocol.
+ */
+static int pohmelfs_remove_response(struct netfs_state *st)
+{
+        struct netfs_cmd *cmd = &st->cmd;
+        int err;
+
+        err = pohmelfs_data_recv_and_check(st, st->data, cmd->size);
+        if (err)
+                return err;
+
+        dprintk("%s: parent: %llu, path: '%s'.\n", __func__, cmd->id, (char *)st->data);
+
+        return 0;
+}
+
+/*
+ * Transaction reply processing.
+ *
+ * Find transaction based on its generation number, bump its reference counter,
+ * so that none could free it under us, drop from the trees and lists and
+ * drop reference counter. When it hits zero (when all destinations replied
+ * and all timeout handled by async scanning code), completion will be called
+ * and transaction will be freed.
+ */
+static int pohmelfs_transaction_response(struct netfs_state *st)
+{
+        struct netfs_trans_dst *dst;
+        struct netfs_trans *t = NULL;
+        struct netfs_cmd *cmd = &st->cmd;
+        short err = (signed)cmd->ext;
+
+        mutex_lock(&st->trans_lock);
+        dst = netfs_trans_search(st, cmd->start);
+        if (dst) {
+                netfs_trans_remove_nolock(dst, st);
+                t = dst->trans;
+        }
+        mutex_unlock(&st->trans_lock);
+
+        if (!t) {
+                printk("%s: failed to find transaction: start: %llu: id: %llu, size: %u, ext: %u.\n",
+                                __func__, cmd->start, cmd->id, cmd->size, cmd->ext);
+                err = -EINVAL;
+                goto out;
+        }
+
+        t->result = err;
+        netfs_trans_drop_dst_nostate(dst);
+
+out:
+        wake_up(&st->psb->wait);
+        return err;
+}
+
+/*
+ * Inode metadata cache coherency message.
+ */
+static int pohmelfs_page_cache_response(struct netfs_state *st)
+{
+        struct netfs_cmd *cmd = &st->cmd;
+        struct inode *inode;
+
+        dprintk("%s: st: %p, id: %llu, start: %llu, size: %u.\n", __func__, st, cmd->id, cmd->start, cmd->size);
+
+        inode = ilookup(st->psb->sb, cmd->id);
+        if (!inode) {
+                printk("%s: failed to find inode: id: %llu.\n", __func__, cmd->id);
+                return -ENOENT;
+        }
+
+        set_bit(NETFS_INODE_NEED_FLUSH, &POHMELFS_I(inode)->state);
+        pohmelfs_put_inode(POHMELFS_I(inode));
+
+        return 0;
+}
+
+/*
+ * Root capabilities response: export statistics
+ * like used and available size, number of files and dirs,
+ * permissions.
+ */
+static int pohmelfs_root_cap_response(struct netfs_state *st)
+{
+        struct netfs_cmd *cmd = &st->cmd;
+        struct netfs_root_capabilities *cap;
+        struct pohmelfs_sb *psb = st->psb;
+
+        if (cmd->size != sizeof(struct netfs_root_capabilities)) {
+                psb->flags = EPROTO;
+                wake_up(&psb->wait);
+                return -EPROTO;
+        }
+
+        cap = st->data;
+
+        netfs_convert_root_capabilities(cap);
+
+        if (psb->total_size < cap->used + cap->avail)
+                psb->total_size = cap->used + cap->avail;
+        if (cap->avail)
+                psb->avail_size = cap->avail;
+        psb->state_flags = cap->flags;
+
+        if (psb->state_flags & POHMELFS_FLAGS_RO) {
+                psb->sb->s_flags |= MS_RDONLY;
+                printk(KERN_INFO "Mounting POHMELFS (%d) read-only.\n", psb->idx);
+        }
+
+        if (psb->state_flags & POHMELFS_FLAGS_XATTR)
+                printk(KERN_INFO "Mounting POHMELFS (%d) "
+                        "with extended attributes support.\n", psb->idx);
+
+        if (atomic_long_read(&psb->total_inodes) <= 1)
+                atomic_long_set(&psb->total_inodes, cap->nr_files);
+
+        dprintk("%s: total: %llu, avail: %llu, flags: %llx, inodes: %llu.\n",
+                __func__, psb->total_size, psb->avail_size, psb->state_flags, cap->nr_files);
+
+        psb->flags = 0;
+        wake_up(&psb->wait);
+        return 0;
+}
+
+/*
+ * Crypto capabilities of the server, where it says that
+ * it supports or does not requested hash/cipher algorithms.
+ */
+static int pohmelfs_crypto_cap_response(struct netfs_state *st)
+{
+        struct netfs_cmd *cmd = &st->cmd;
+        struct netfs_crypto_capabilities *cap;
+        struct pohmelfs_sb *psb = st->psb;
+        int err = 0;
+
+        if (cmd->size != sizeof(struct netfs_crypto_capabilities)) {
+                psb->flags = EPROTO;
+                wake_up(&psb->wait);
+                return -EPROTO;
+        }
+
+        cap = st->data;
+
+        dprintk("%s: cipher '%s': %s, hash: '%s': %s.\n",
+                        __func__,
+                        psb->cipher_string, (cap->cipher_strlen) ? "SUPPORTED" : "NOT SUPPORTED",
+                        psb->hash_string, (cap->hash_strlen) ? "SUPPORTED" : "NOT SUPPORTED");
+
+        if (!cap->hash_strlen) {
+                if (psb->hash_strlen && psb->crypto_fail_unsupported)
+                        err = -ENOTSUPP;
+                psb->hash_strlen = 0;
+                kfree(psb->hash_string);
+                psb->hash_string = NULL;
+        }
+
+        if (!cap->cipher_strlen) {
+                if (psb->cipher_strlen && psb->crypto_fail_unsupported)
+                        err = -ENOTSUPP;
+                psb->cipher_strlen = 0;
+                kfree(psb->cipher_string);
+                psb->cipher_string = NULL;
+        }
+
+        return err;
+}
+
+/*
+ * Capabilities handshake response.
+ */
+static int pohmelfs_capabilities_response(struct netfs_state *st)
+{
+        struct netfs_cmd *cmd = &st->cmd;
+        int err = 0;
+
+        err = pohmelfs_data_recv(st, st->data, cmd->size);
+        if (err)
+                return err;
+
+        switch (cmd->id) {
+        case POHMELFS_CRYPTO_CAPABILITIES:
+                        return pohmelfs_crypto_cap_response(st);
+        case POHMELFS_ROOT_CAPABILITIES:
+                        return pohmelfs_root_cap_response(st);
+        default:
+                        break;
+        }
+        return -EINVAL;
+}
+
+/*
+ * Receiving extended attribute.
+ * Does not work properly if received size is more than requested one,
+ * it should not happen with current request/reply model though.
+ */
+static int pohmelfs_getxattr_response(struct netfs_state *st)
+{
+        struct pohmelfs_sb *psb = st->psb;
+        struct netfs_cmd *cmd = &st->cmd;
+        struct pohmelfs_mcache *m;
+        short error = (signed short)cmd->ext, err;
+        unsigned int sz, total_size;
+
+        m = pohmelfs_mcache_search(psb, cmd->id);
+
+        dprintk("%s: id: %llu, gen: %llu, err: %d.\n",
+                __func__, cmd->id, (m) ? m->gen : 0, error);
+
+        if (!m) {
+                printk("%s: failed to find getxattr cache entry: id: %llu.\n", __func__, cmd->id);
+                return -ENOENT;
+        }
+
+        if (cmd->size) {
+                sz = min_t(unsigned int, cmd->size, m->size);
+                err = pohmelfs_data_recv_and_check(st, m->data, sz);
+                if (err) {
+                        error = err;
+                        goto out;
+                }
+
+                m->size = sz;
+                total_size = cmd->size - sz;
+
+                while (total_size) {
+                        sz = min(total_size, st->size);
+
+                        err = pohmelfs_data_recv_and_check(st, st->data, sz);
+                        if (err) {
+                                error = err;
+                                break;
+                        }
+
+                        total_size -= sz;
+                }
+        }
+
+out:
+        m->err = error;
+        complete(&m->complete);
+        pohmelfs_mcache_put(psb, m);
+
+        return error;
+}
+
+int pohmelfs_data_lock_response(struct netfs_state *st)
+{
+        struct pohmelfs_sb *psb = st->psb;
+        struct netfs_cmd *cmd = &st->cmd;
+        struct pohmelfs_mcache *m;
+        short err = (signed short)cmd->ext;
+        u64 id = cmd->id;
+
+        m = pohmelfs_mcache_search(psb, id);
+
+        dprintk("%s: id: %llu, gen: %llu, err: %d.\n",
+                __func__, cmd->id, (m) ? m->gen : 0, err);
+
+        if (!m) {
+                pohmelfs_data_recv(st, st->data, cmd->size);
+                printk("%s: failed to find data lock response: id: %llu.\n", __func__, cmd->id);
+                return -ENOENT;
+        }
+
+        if (cmd->size)
+                err = pohmelfs_data_recv_and_check(st, &m->info, cmd->size);
+
+        m->err = err;
+        complete(&m->complete);
+        pohmelfs_mcache_put(psb, m);
+
+        return err;
+}
+
+static void __inline__ netfs_state_reset(struct netfs_state *st)
+{
+        netfs_state_lock_send(st);
+        netfs_state_exit(st);
+        netfs_state_init(st);
+        netfs_state_unlock_send(st);
+}
+
+/*
+ * Main receiving function, called from dedicated kernel thread.
+ */
+static int pohmelfs_recv(void *data)
+{
+        int err = -EINTR;
+        struct netfs_state *st = data;
+        struct netfs_cmd *cmd = &st->cmd;
+
+        while (!kthread_should_stop()) {
+                /*
+                 * If socket will be reset after this statement, then
+                 * pohmelfs_data_recv() will just fail and loop will
+                 * start again, so it can be done without any locks.
+                 *
+                 * st->read_socket is needed to prevents state machine
+                 * breaking between this data reading and subsequent one
+                 * in protocol specific functions during connection reset.
+                 * In case of reset we have to read next command and do
+                 * not expect data for old command to magically appear in
+                 * new connection.
+                 */
+                st->read_socket = st->socket;
+                err = pohmelfs_data_recv(st, cmd, sizeof(struct netfs_cmd));
+                if (err) {
+                        msleep(1000);
+                        continue;
+                }
+
+                netfs_convert_cmd(cmd);
+
+                dprintk("%s: cmd: %u, id: %llu, start: %llu, size: %u, "
+                                "ext: %u, csize: %u, cpad: %u.\n",
+                                __func__, cmd->cmd, cmd->id, cmd->start,
+                                cmd->size, cmd->ext, cmd->csize, cmd->cpad);
+
+                if (cmd->csize) {
+                        struct pohmelfs_crypto_engine *e = &st->eng;
+
+                        if (unlikely(cmd->csize > e->size/2)) {
+                                netfs_state_reset(st);
+                                continue;
+                        }
+
+                        if (e->hash && unlikely(cmd->csize != st->psb->crypto_attached_size)) {
+                                dprintk("%s: cmd: cmd: %u, id: %llu, start: %llu, size: %u, "
+                                                "csize: %u != digest size %u.\n",
+                                                __func__, cmd->cmd, cmd->id, cmd->start, cmd->size,
+                                                cmd->csize, st->psb->crypto_attached_size);
+                                netfs_state_reset(st);
+                                continue;
+                        }
+
+                        err = pohmelfs_data_recv(st, e->data, cmd->csize);
+                        if (err) {
+                                netfs_state_reset(st);
+                                continue;
+                        }
+
+#ifdef CONFIG_POHMELFS_DEBUG
+                        {
+                                unsigned int i;
+                                unsigned char *hash = e->data;
+
+                                dprintk("%s: received hash: ", __func__);
+                                for (i = 0; i < cmd->csize; ++i)
+                                        printk("%02x ", hash[i]);
+
+                                printk("\n");
+                        }
+#endif
+                        cmd->size -= cmd->csize;
+                }
+
+                /*
+                 * This should catch protocol breakage and random garbage instead of commands.
+                 */
+                if (unlikely((cmd->size > st->size) && (cmd->cmd != NETFS_XATTR_GET))) {
+                        netfs_state_reset(st);
+                        continue;
+                }
+
+                switch (cmd->cmd) {
+                case NETFS_READ_PAGE:
+                                err = pohmelfs_read_page_response(st);
+                                break;
+                case NETFS_READDIR:
+                                err = pohmelfs_readdir_response(st);
+                                break;
+                case NETFS_LOOKUP:
+                                err = pohmelfs_lookup_response(st);
+                                break;
+                case NETFS_CREATE:
+                                err = pohmelfs_create_response(st);
+                                break;
+                case NETFS_REMOVE:
+                                err = pohmelfs_remove_response(st);
+                                break;
+                case NETFS_TRANS:
+                                err = pohmelfs_transaction_response(st);
+                                break;
+                case NETFS_PAGE_CACHE:
+                                err = pohmelfs_page_cache_response(st);
+                                break;
+                case NETFS_CAPABILITIES:
+                                err = pohmelfs_capabilities_response(st);
+                                break;
+                case NETFS_LOCK:
+                                err = pohmelfs_data_lock_response(st);
+                                break;
+                case NETFS_XATTR_GET:
+                                err = pohmelfs_getxattr_response(st);
+                                break;
+                default:
+                                printk("%s: wrong cmd: %u, id: %llu, start: %llu, size: %u, ext: %u.\n",
+                                        __func__, cmd->cmd, cmd->id, cmd->start, cmd->size, cmd->ext);
+                                netfs_state_reset(st);
+                                break;
+                }
+        }
+
+        while (!kthread_should_stop())
+                schedule_timeout_uninterruptible(msecs_to_jiffies(10));
+
+        return err;
+}
+
+int netfs_state_init(struct netfs_state *st)
+{
+        int err;
+        struct pohmelfs_ctl *ctl = &st->ctl;
+
+        err = sock_create(ctl->addr.sa_family, ctl->type, ctl->proto, &st->socket);
+        if (err) {
+                printk("%s: failed to create a socket: family: %d, type: %d, proto: %d, err: %d.\n",
+                                __func__, ctl->addr.sa_family, ctl->type, ctl->proto, err);
+                goto err_out_exit;
+        }
+
+        st->socket->sk->sk_allocation = GFP_NOIO;
+        st->socket->sk->sk_sndtimeo = st->socket->sk->sk_rcvtimeo = msecs_to_jiffies(60000);
+
+        err = kernel_connect(st->socket, (struct sockaddr *)&ctl->addr, ctl->addrlen, 0);
+        if (err) {
+                printk("%s: failed to connect to server: idx: %u, err: %d.\n",
+                                __func__, st->psb->idx, err);
+                goto err_out_release;
+        }
+        st->socket->sk->sk_sndtimeo = st->socket->sk->sk_rcvtimeo = msecs_to_jiffies(60000);
+
+        err = netfs_poll_init(st);
+        if (err)
+                goto err_out_release;
+
+        if (st->socket->ops->family == AF_INET) {
+                struct sockaddr_in *sin = (struct sockaddr_in *)&ctl->addr;
+                printk(KERN_INFO "%s: (re)connected to peer %pi4:%d.\n", __func__,
+                        &sin->sin_addr.s_addr, ntohs(sin->sin_port));
+        } else if (st->socket->ops->family == AF_INET6) {
+                struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&ctl->addr;
+                printk(KERN_INFO "%s: (re)connected to peer %pi6:%d", __func__,
+                                &sin->sin6_addr, ntohs(sin->sin6_port));
+        }
+
+        return 0;
+
+err_out_release:
+        sock_release(st->socket);
+err_out_exit:
+        st->socket = NULL;
+        return err;
+}
+
+void netfs_state_exit(struct netfs_state *st)
+{
+        if (st->socket) {
+                netfs_poll_exit(st);
+                st->socket->ops->shutdown(st->socket, 2);
+
+                if (st->socket->ops->family == AF_INET) {
+                        struct sockaddr_in *sin = (struct sockaddr_in *)&st->ctl.addr;
+                        printk(KERN_INFO "%s: disconnected from peer %pi4:%d.\n", __func__,
+                                &sin->sin_addr.s_addr, ntohs(sin->sin_port));
+                } else if (st->socket->ops->family == AF_INET6) {
+                        struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&st->ctl.addr;
+                        printk(KERN_INFO "%s: disconnected from peer %pi6:%d", __func__,
+                                &sin->sin6_addr, ntohs(sin->sin6_port));
+                }
+
+                sock_release(st->socket);
+                st->socket = NULL;
+                st->read_socket = NULL;
+                st->need_reset = 0;
+        }
+}
+
+int pohmelfs_state_init_one(struct pohmelfs_sb *psb, struct pohmelfs_config *conf)
+{
+        struct netfs_state *st = &conf->state;
+        int err = -ENOMEM;
+
+        mutex_init(&st->__state_lock);
+        mutex_init(&st->__state_send_lock);
+        init_waitqueue_head(&st->thread_wait);
+
+        st->psb = psb;
+        st->trans_root = RB_ROOT;
+        mutex_init(&st->trans_lock);
+
+        st->size = psb->trans_data_size;
+        st->data = kmalloc(st->size, GFP_KERNEL);
+        if (!st->data)
+                goto err_out_exit;
+
+        if (psb->perform_crypto) {
+                err = pohmelfs_crypto_engine_init(&st->eng, psb);
+                if (err)
+                        goto err_out_free_data;
+        }
+
+        err = netfs_state_init(st);
+        if (err)
+                goto err_out_free_engine;
+
+        st->thread = kthread_run(pohmelfs_recv, st, "pohmelfs/%u", psb->idx);
+        if (IS_ERR(st->thread)) {
+                err = PTR_ERR(st->thread);
+                goto err_out_netfs_exit;
+        }
+
+        if (!psb->active_state)
+                psb->active_state = conf;
+
+        dprintk("%s: conf: %p, st: %p, socket: %p.\n",
+                        __func__, conf, st, st->socket);
+        return 0;
+
+err_out_netfs_exit:
+        netfs_state_exit(st);
+err_out_free_engine:
+        pohmelfs_crypto_engine_exit(&st->eng);
+err_out_free_data:
+        kfree(st->data);
+err_out_exit:
+        return err;
+
+}
+
+void pohmelfs_state_flush_transactions(struct netfs_state *st)
+{
+        struct rb_node *rb_node;
+        struct netfs_trans_dst *dst;
+
+        mutex_lock(&st->trans_lock);
+        for (rb_node = rb_first(&st->trans_root); rb_node; ) {
+                dst = rb_entry(rb_node, struct netfs_trans_dst, state_entry);
+                rb_node = rb_next(rb_node);
+
+                dst->trans->result = -EINVAL;
+                netfs_trans_remove_nolock(dst, st);
+                netfs_trans_drop_dst_nostate(dst);
+        }
+        mutex_unlock(&st->trans_lock);
+}
+
+static void pohmelfs_state_exit_one(struct pohmelfs_config *c)
+{
+        struct netfs_state *st = &c->state;
+
+        dprintk("%s: exiting, st: %p.\n", __func__, st);
+        if (st->thread) {
+                kthread_stop(st->thread);
+                st->thread = NULL;
+        }
+
+        netfs_state_lock_send(st);
+        netfs_state_exit(st);
+        netfs_state_unlock_send(st);
+
+        pohmelfs_state_flush_transactions(st);
+
+        pohmelfs_crypto_engine_exit(&st->eng);
+        kfree(st->data);
+
+        kfree(c);
+}
+
+/*
+ * Initialize network stack. It searches for given ID in global
+ * configuration table, this contains information of the remote server
+ * (address (any supported by socket interface) and port, protocol and so on).
+ */
+int pohmelfs_state_init(struct pohmelfs_sb *psb)
+{
+        int err = -ENOMEM;
+
+        err = pohmelfs_copy_config(psb);
+        if (err) {
+                pohmelfs_state_exit(psb);
+                return err;
+        }
+
+        return 0;
+}
+
+void pohmelfs_state_exit(struct pohmelfs_sb *psb)
+{
+        struct pohmelfs_config *c, *tmp;
+
+        list_for_each_entry_safe(c, tmp, &psb->state_list, config_entry) {
+                list_del(&c->config_entry);
+                pohmelfs_state_exit_one(c);
+        }
+}
+
+void pohmelfs_switch_active(struct pohmelfs_sb *psb)
+{
+        struct pohmelfs_config *c = psb->active_state;
+
+        if (!list_empty(&psb->state_list)) {
+                if (c->config_entry.next != &psb->state_list) {
+                        psb->active_state = list_entry(c->config_entry.next,
+                                struct pohmelfs_config, config_entry);
+                } else {
+                        psb->active_state = list_entry(psb->state_list.next,
+                                struct pohmelfs_config, config_entry);
+                }
+
+                dprintk("%s: empty: %d, active %p -> %p.\n",
+                        __func__, list_empty(&psb->state_list), c,
+                        psb->active_state);
+        } else
+                psb->active_state = NULL;
+}
+
+void pohmelfs_check_states(struct pohmelfs_sb *psb)
+{
+        struct pohmelfs_config *c, *tmp;
+        LIST_HEAD(delete_list);
+
+        mutex_lock(&psb->state_lock);
+        list_for_each_entry_safe(c, tmp, &psb->state_list, config_entry) {
+                if (pohmelfs_config_check(c, psb->idx)) {
+
+                        if (psb->active_state == c)
+                                pohmelfs_switch_active(psb);
+                        list_move(&c->config_entry, &delete_list);
+                }
+        }
+        pohmelfs_copy_config(psb);
+        mutex_unlock(&psb->state_lock);
+
+        list_for_each_entry_safe(c, tmp, &delete_list, config_entry) {
+                list_del(&c->config_entry);
+                pohmelfs_state_exit_one(c);
+        }
+}
diff --git a/drivers/staging/pohmelfs/netfs.h b/drivers/staging/pohmelfs/netfs.h
new file mode 100644
index 00000000000..985b6b755d5
--- /dev/null
+++ b/drivers/staging/pohmelfs/netfs.h
@@ -0,0 +1,919 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __NETFS_H
+#define __NETFS_H
+
+#include <linux/types.h>
+#include <linux/connector.h>
+#include <linux/backing-dev.h>
+
+#define POHMELFS_CN_IDX                 5
+#define POHMELFS_CN_VAL                 0
+
+#define POHMELFS_CTLINFO_ACK            1
+#define POHMELFS_NOINFO_ACK             2
+
+#define POHMELFS_NULL_IDX               65535
+
+/*
+ * Network command structure.
+ * Will be extended.
+ */
+struct netfs_cmd {
+        __u16                   cmd;    /* Command number */
+        __u16                   csize;  /* Attached crypto information size */
+        __u16                   cpad;   /* Attached padding size */
+        __u16                   ext;    /* External flags */
+        __u32                   size;   /* Size of the attached data */
+        __u32                   trans;  /* Transaction id */
+        __u64                   id;     /* Object ID to operate on. Used for feedback.*/
+        __u64                   start;  /* Start of the object. */
+        __u64                   iv;     /* IV sequence */
+        __u8                    data[0];
+};
+
+static inline void netfs_convert_cmd(struct netfs_cmd *cmd)
+{
+        cmd->id = __be64_to_cpu(cmd->id);
+        cmd->start = __be64_to_cpu(cmd->start);
+        cmd->iv = __be64_to_cpu(cmd->iv);
+        cmd->cmd = __be16_to_cpu(cmd->cmd);
+        cmd->ext = __be16_to_cpu(cmd->ext);
+        cmd->csize = __be16_to_cpu(cmd->csize);
+        cmd->cpad = __be16_to_cpu(cmd->cpad);
+        cmd->size = __be32_to_cpu(cmd->size);
+}
+
+#define NETFS_TRANS_SINGLE_DST          (1<<0)
+
+enum {
+        NETFS_READDIR   = 1,    /* Read directory for given inode number */
+        NETFS_READ_PAGE,        /* Read data page from the server */
+        NETFS_WRITE_PAGE,       /* Write data page to the server */
+        NETFS_CREATE,           /* Create directory entry */
+        NETFS_REMOVE,           /* Remove directory entry */
+
+        NETFS_LOOKUP,           /* Lookup single object */
+        NETFS_LINK,             /* Create a link */
+        NETFS_TRANS,            /* Transaction */
+        NETFS_OPEN,             /* Open intent */
+        NETFS_INODE_INFO,       /* Metadata cache coherency synchronization message */
+
+        NETFS_PAGE_CACHE,       /* Page cache invalidation message */
+        NETFS_READ_PAGES,       /* Read multiple contiguous pages in one go */
+        NETFS_RENAME,           /* Rename object */
+        NETFS_CAPABILITIES,     /* Capabilities of the client, for example supported crypto */
+        NETFS_LOCK,             /* Distributed lock message */
+
+        NETFS_XATTR_SET,        /* Set extended attribute */
+        NETFS_XATTR_GET,        /* Get extended attribute */
+        NETFS_CMD_MAX
+};
+
+enum {
+        POHMELFS_FLAGS_ADD = 0, /* Network state control message for ADD */
+        POHMELFS_FLAGS_DEL,     /* Network state control message for DEL */
+        POHMELFS_FLAGS_SHOW,    /* Network state control message for SHOW */
+        POHMELFS_FLAGS_CRYPTO,  /* Crypto data control message */
+        POHMELFS_FLAGS_MODIFY,  /* Network state modification message */
+        POHMELFS_FLAGS_DUMP,    /* Network state control message for SHOW ALL */
+        POHMELFS_FLAGS_FLUSH,   /* Network state control message for FLUSH */
+};
+
+/*
+ * Always wanted to copy it from socket headers into public one,
+ * since they are __KERNEL__ protected there.
+ */
+#define _K_SS_MAXSIZE   128
+
+struct saddr {
+        unsigned short          sa_family;
+        char                    addr[_K_SS_MAXSIZE];
+};
+
+enum {
+        POHMELFS_CRYPTO_HASH = 0,
+        POHMELFS_CRYPTO_CIPHER,
+};
+
+struct pohmelfs_crypto {
+        unsigned int            idx;            /* Config index */
+        unsigned short          strlen;         /* Size of the attached crypto string including 0-byte
+                                                 * "cbc(aes)" for example */
+        unsigned short          type;           /* HMAC, cipher, both */
+        unsigned int            keysize;        /* Key size */
+        unsigned char           data[0];        /* Algorithm string, key and IV */
+};
+
+#define POHMELFS_IO_PERM_READ           (1<<0)
+#define POHMELFS_IO_PERM_WRITE          (1<<1)
+
+/*
+ * Configuration command used to create table of different remote servers.
+ */
+struct pohmelfs_ctl {
+        __u32                   idx;            /* Config index */
+        __u32                   type;           /* Socket type */
+        __u32                   proto;          /* Socket protocol */
+        __u16                   addrlen;        /* Size of the address */
+        __u16                   perm;           /* IO permission */
+        __u16                   prio;           /* IO priority */
+        struct saddr            addr;           /* Remote server address */
+};
+
+/*
+ * Ack for userspace about requested command.
+ */
+struct pohmelfs_cn_ack {
+        struct cn_msg           msg;
+        int                     error;
+        int                     msg_num;
+        int                     unused[3];
+        struct pohmelfs_ctl     ctl;
+};
+
+/*
+ * Inode info structure used to sync with server.
+ * Check what stat() returns.
+ */
+struct netfs_inode_info {
+        unsigned int            mode;
+        unsigned int            nlink;
+        unsigned int            uid;
+        unsigned int            gid;
+        unsigned int            blocksize;
+        unsigned int            padding;
+        __u64                   ino;
+        __u64                   blocks;
+        __u64                   rdev;
+        __u64                   size;
+        __u64                   version;
+};
+
+static inline void netfs_convert_inode_info(struct netfs_inode_info *info)
+{
+        info->mode = __cpu_to_be32(info->mode);
+        info->nlink = __cpu_to_be32(info->nlink);
+        info->uid = __cpu_to_be32(info->uid);
+        info->gid = __cpu_to_be32(info->gid);
+        info->blocksize = __cpu_to_be32(info->blocksize);
+        info->blocks = __cpu_to_be64(info->blocks);
+        info->rdev = __cpu_to_be64(info->rdev);
+        info->size = __cpu_to_be64(info->size);
+        info->version = __cpu_to_be64(info->version);
+        info->ino = __cpu_to_be64(info->ino);
+}
+
+/*
+ * Cache state machine.
+ */
+enum {
+        NETFS_COMMAND_PENDING = 0,      /* Command is being executed */
+        NETFS_INODE_REMOTE_SYNCED,      /* Inode was synced to server */
+        NETFS_INODE_REMOTE_DIR_SYNCED,  /* Inode (directory) was synced from the server */
+        NETFS_INODE_OWNED,              /* Inode is owned by given host */
+        NETFS_INODE_NEED_FLUSH,         /* Inode has to be flushed to the server */
+};
+
+/*
+ * POHMELFS capabilities: information about supported
+ * crypto operations (hash/cipher, modes, key sizes and so on),
+ * root information (used/available size, number of objects, permissions)
+ */
+enum pohmelfs_capabilities {
+        POHMELFS_CRYPTO_CAPABILITIES = 0,
+        POHMELFS_ROOT_CAPABILITIES,
+};
+
+/* Read-only mount */
+#define POHMELFS_FLAGS_RO               (1<<0)
+/* Extended attributes support on/off */
+#define POHMELFS_FLAGS_XATTR            (1<<1)
+
+struct netfs_root_capabilities {
+        __u64                   nr_files;
+        __u64                   used, avail;
+        __u64                   flags;
+};
+
+static inline void netfs_convert_root_capabilities(struct netfs_root_capabilities *cap)
+{
+        cap->nr_files = __cpu_to_be64(cap->nr_files);
+        cap->used = __cpu_to_be64(cap->used);
+        cap->avail = __cpu_to_be64(cap->avail);
+        cap->flags = __cpu_to_be64(cap->flags);
+}
+
+struct netfs_crypto_capabilities {
+        unsigned short          hash_strlen;    /* Hash string length, like "hmac(sha1) including 0 byte "*/
+        unsigned short          cipher_strlen;  /* Cipher string length with the same format */
+        unsigned int            cipher_keysize; /* Cipher key size */
+};
+
+static inline void netfs_convert_crypto_capabilities(struct netfs_crypto_capabilities *cap)
+{
+        cap->hash_strlen = __cpu_to_be16(cap->hash_strlen);
+        cap->cipher_strlen = __cpu_to_be16(cap->cipher_strlen);
+        cap->cipher_keysize = __cpu_to_be32(cap->cipher_keysize);
+}
+
+enum pohmelfs_lock_type {
+        POHMELFS_LOCK_GRAB      = (1<<15),
+
+        POHMELFS_READ_LOCK      = 0,
+        POHMELFS_WRITE_LOCK,
+};
+
+struct netfs_lock {
+        __u64                   start;
+        __u64                   ino;
+        __u32                   size;
+        __u32                   type;
+};
+
+static inline void netfs_convert_lock(struct netfs_lock *lock)
+{
+        lock->start = __cpu_to_be64(lock->start);
+        lock->ino = __cpu_to_be64(lock->ino);
+        lock->size = __cpu_to_be32(lock->size);
+        lock->type = __cpu_to_be32(lock->type);
+}
+
+#ifdef __KERNEL__
+
+#include <linux/kernel.h>
+#include <linux/completion.h>
+#include <linux/rbtree.h>
+#include <linux/net.h>
+#include <linux/poll.h>
+
+/*
+ * Private POHMELFS cache of objects in directory.
+ */
+struct pohmelfs_name {
+        struct rb_node          hash_node;
+
+        struct list_head        sync_create_entry;
+
+        u64                     ino;
+
+        u32                     hash;
+        u32                     mode;
+        u32                     len;
+
+        char                    *data;
+};
+
+/*
+ * POHMELFS inode. Main object.
+ */
+struct pohmelfs_inode {
+        struct list_head        inode_entry;            /* Entry in superblock list.
+                                                         * Objects which are not bound to dentry require to be dropped
+                                                         * in ->put_super()
+                                                         */
+        struct rb_root          hash_root;              /* The same, but indexed by name hash and len */
+        struct mutex            offset_lock;            /* Protect both above trees */
+
+        struct list_head        sync_create_list;       /* List of created but not yet synced to the server children */
+
+        unsigned int            drop_count;
+
+        int                     lock_type;              /* How this inode is locked: read or write */
+
+        int                     error;                  /* Transaction error for given inode */
+
+        long                    state;                  /* State machine above */
+
+        u64                     ino;                    /* Inode number */
+        u64                     total_len;              /* Total length of all children names, used to create offsets */
+
+        struct inode            vfs_inode;
+};
+
+struct netfs_trans;
+typedef int (*netfs_trans_complete_t)(struct page **pages, unsigned int page_num,
+                void *private, int err);
+
+struct netfs_state;
+struct pohmelfs_sb;
+
+struct netfs_trans {
+        /*
+         * Transaction header and attached contiguous data live here.
+         */
+        struct iovec                    iovec;
+
+        /*
+         * Pages attached to transaction.
+         */
+        struct page                     **pages;
+
+        /*
+         * List and protecting lock for transaction destination
+         * network states.
+         */
+        spinlock_t                      dst_lock;
+        struct list_head                dst_list;
+
+        /*
+         * Number of users for given transaction.
+         * For example each network state attached to transaction
+         * via dst_list increases it.
+         */
+        atomic_t                        refcnt;
+
+        /*
+         * Number of pages attached to given transaction.
+         * Some slots in above page array can be NULL, since
+         * for example page can be under writeback already,
+         * so we skip it in this transaction.
+         */
+        unsigned int                    page_num;
+
+        /*
+         * Transaction flags: single dst or broadcast and so on.
+         */
+        unsigned int                    flags;
+
+        /*
+         * Size of the data, which can be placed into
+         * iovec.iov_base area.
+         */
+        unsigned int                    total_size;
+
+        /*
+         * Number of pages to be sent to remote server.
+         * Usually equal to above page_num, but in case of partial
+         * writeback it can accumulate only pages already completed
+         * previous writeback.
+         */
+        unsigned int                    attached_pages;
+
+        /*
+         * Attached number of bytes in all above pages.
+         */
+        unsigned int                    attached_size;
+
+        /*
+         * Unique transacton generation number.
+         * Used as identity in the network state tree of transactions.
+         */
+        unsigned int                    gen;
+
+        /*
+         * Transaction completion status.
+         */
+        int                             result;
+
+        /*
+         * Superblock this transaction belongs to
+         */
+        struct pohmelfs_sb              *psb;
+
+        /*
+         * Crypto engine, which processed this transaction.
+         * Can be not NULL only if crypto engine holds encrypted pages.
+         */
+        struct pohmelfs_crypto_engine   *eng;
+
+        /* Private data */
+        void                            *private;
+
+        /* Completion callback, invoked just before transaction is destroyed */
+        netfs_trans_complete_t          complete;
+};
+
+static inline int netfs_trans_cur_len(struct netfs_trans *t)
+{
+        return (signed)(t->total_size - t->iovec.iov_len);
+}
+
+static inline void *netfs_trans_current(struct netfs_trans *t)
+{
+        return t->iovec.iov_base + t->iovec.iov_len;
+}
+
+struct netfs_trans *netfs_trans_alloc(struct pohmelfs_sb *psb, unsigned int size,
+                unsigned int flags, unsigned int nr);
+void netfs_trans_free(struct netfs_trans *t);
+int netfs_trans_finish(struct netfs_trans *t, struct pohmelfs_sb *psb);
+int netfs_trans_finish_send(struct netfs_trans *t, struct pohmelfs_sb *psb);
+
+static inline void netfs_trans_reset(struct netfs_trans *t)
+{
+        t->complete = NULL;
+}
+
+struct netfs_trans_dst {
+        struct list_head                trans_entry;
+        struct rb_node                  state_entry;
+
+        unsigned long                   send_time;
+
+        /*
+         * Times this transaction was resent to its old or new,
+         * depending on flags, destinations. When it reaches maximum
+         * allowed number, specified in superblock->trans_retries,
+         * transaction will be freed with ETIMEDOUT error.
+         */
+        unsigned int                    retries;
+
+        struct netfs_trans              *trans;
+        struct netfs_state              *state;
+};
+
+struct netfs_trans_dst *netfs_trans_search(struct netfs_state *st, unsigned int gen);
+void netfs_trans_drop_dst(struct netfs_trans_dst *dst);
+void netfs_trans_drop_dst_nostate(struct netfs_trans_dst *dst);
+void netfs_trans_drop_trans(struct netfs_trans *t, struct netfs_state *st);
+void netfs_trans_drop_last(struct netfs_trans *t, struct netfs_state *st);
+int netfs_trans_resend(struct netfs_trans *t, struct pohmelfs_sb *psb);
+int netfs_trans_remove_nolock(struct netfs_trans_dst *dst, struct netfs_state *st);
+
+int netfs_trans_init(void);
+void netfs_trans_exit(void);
+
+struct pohmelfs_crypto_engine {
+        u64                             iv;             /* Crypto IV for current operation */
+        unsigned long                   timeout;        /* Crypto waiting timeout */
+        unsigned int                    size;           /* Size of crypto scratchpad */
+        void                            *data;          /* Temporal crypto scratchpad */
+        /*
+         * Crypto operations performed on objects.
+         */
+        struct crypto_hash              *hash;
+        struct crypto_ablkcipher        *cipher;
+
+        struct pohmelfs_crypto_thread   *thread;        /* Crypto thread which hosts this engine */
+
+        struct page                     **pages;
+        unsigned int                    page_num;
+};
+
+struct pohmelfs_crypto_thread {
+        struct list_head                thread_entry;
+
+        struct task_struct              *thread;
+        struct pohmelfs_sb              *psb;
+
+        struct pohmelfs_crypto_engine   eng;
+
+        struct netfs_trans              *trans;
+
+        wait_queue_head_t               wait;
+        int                             error;
+
+        unsigned int                    size;
+        struct page                     *page;
+};
+
+void pohmelfs_crypto_thread_make_ready(struct pohmelfs_crypto_thread *th);
+
+/*
+ * Network state, attached to one server.
+ */
+struct netfs_state {
+        struct mutex            __state_lock;           /* Can not allow to use the same socket simultaneously */
+        struct mutex            __state_send_lock;
+        struct netfs_cmd        cmd;                    /* Cached command */
+        struct netfs_inode_info info;                   /* Cached inode info */
+
+        void                    *data;                  /* Cached some data */
+        unsigned int            size;                   /* Size of that data */
+
+        struct pohmelfs_sb      *psb;                   /* Superblock */
+
+        struct task_struct      *thread;                /* Async receiving thread */
+
+        /* Waiting/polling machinery */
+        wait_queue_t            wait;
+        wait_queue_head_t       *whead;
+        wait_queue_head_t       thread_wait;
+
+        struct mutex            trans_lock;
+        struct rb_root          trans_root;
+
+        struct pohmelfs_ctl     ctl;                    /* Remote peer */
+
+        struct socket           *socket;                /* Socket object */
+        struct socket           *read_socket;           /* Cached pointer to socket object.
+                                                         * Used to determine if between lock drops socket was changed.
+                                                         * Never used to read data or any kind of access.
+                                                         */
+        /*
+         * Crypto engines to process incoming data.
+         */
+        struct pohmelfs_crypto_engine   eng;
+
+        int                     need_reset;
+};
+
+int netfs_state_init(struct netfs_state *st);
+void netfs_state_exit(struct netfs_state *st);
+
+static inline void netfs_state_lock_send(struct netfs_state *st)
+{
+        mutex_lock(&st->__state_send_lock);
+}
+
+static inline int netfs_state_trylock_send(struct netfs_state *st)
+{
+        return mutex_trylock(&st->__state_send_lock);
+}
+
+static inline void netfs_state_unlock_send(struct netfs_state *st)
+{
+        BUG_ON(!mutex_is_locked(&st->__state_send_lock));
+
+        mutex_unlock(&st->__state_send_lock);
+}
+
+static inline void netfs_state_lock(struct netfs_state *st)
+{
+        mutex_lock(&st->__state_lock);
+}
+
+static inline void netfs_state_unlock(struct netfs_state *st)
+{
+        BUG_ON(!mutex_is_locked(&st->__state_lock));
+
+        mutex_unlock(&st->__state_lock);
+}
+
+static inline unsigned int netfs_state_poll(struct netfs_state *st)
+{
+        unsigned int revents = POLLHUP | POLLERR;
+
+        netfs_state_lock(st);
+        if (st->socket)
+                revents = st->socket->ops->poll(NULL, st->socket, NULL);
+        netfs_state_unlock(st);
+
+        return revents;
+}
+
+struct pohmelfs_config;
+
+struct pohmelfs_sb {
+        struct rb_root          mcache_root;
+        struct mutex            mcache_lock;
+        atomic_long_t           mcache_gen;
+        unsigned long           mcache_timeout;
+
+        unsigned int            idx;
+
+        unsigned int            trans_retries;
+
+        atomic_t                trans_gen;
+
+        unsigned int            crypto_attached_size;
+        unsigned int            crypto_align_size;
+
+        unsigned int            crypto_fail_unsupported;
+
+        unsigned int            crypto_thread_num;
+        struct list_head        crypto_active_list, crypto_ready_list;
+        struct mutex            crypto_thread_lock;
+
+        unsigned int            trans_max_pages;
+        unsigned long           trans_data_size;
+        unsigned long           trans_timeout;
+
+        unsigned long           drop_scan_timeout;
+        unsigned long           trans_scan_timeout;
+
+        unsigned long           wait_on_page_timeout;
+
+        struct list_head        flush_list;
+        struct list_head        drop_list;
+        spinlock_t              ino_lock;
+        u64                     ino;
+
+        /*
+         * Remote nodes POHMELFS connected to.
+         */
+        struct list_head        state_list;
+        struct mutex            state_lock;
+
+        /*
+         * Currently active state to request data from.
+         */
+        struct pohmelfs_config  *active_state;
+
+
+        wait_queue_head_t       wait;
+
+        /*
+         * Timed checks: stale transactions, inodes to be freed and so on.
+         */
+        struct delayed_work     dwork;
+        struct delayed_work     drop_dwork;
+
+        struct super_block      *sb;
+
+        struct backing_dev_info bdi;
+
+        /*
+         * Algorithm strings.
+         */
+        char                    *hash_string;
+        char                    *cipher_string;
+
+        u8                      *hash_key;
+        u8                      *cipher_key;
+
+        /*
+         * Algorithm string lengths.
+         */
+        unsigned int            hash_strlen;
+        unsigned int            cipher_strlen;
+        unsigned int            hash_keysize;
+        unsigned int            cipher_keysize;
+
+        /*
+         * Controls whether to perfrom crypto processing or not.
+         */
+        int                     perform_crypto;
+
+        /*
+         * POHMELFS statistics.
+         */
+        u64                     total_size;
+        u64                     avail_size;
+        atomic_long_t           total_inodes;
+
+        /*
+         * Xattr support, read-only and so on.
+         */
+        u64                     state_flags;
+
+        /*
+         * Temporary storage to detect changes in the wait queue.
+         */
+        long                    flags;
+};
+
+static inline void netfs_trans_update(struct netfs_cmd *cmd,
+                struct netfs_trans *t, unsigned int size)
+{
+        unsigned int sz = ALIGN(size, t->psb->crypto_align_size);
+
+        t->iovec.iov_len += sizeof(struct netfs_cmd) + sz;
+        cmd->cpad = __cpu_to_be16(sz - size);
+}
+
+static inline struct pohmelfs_sb *POHMELFS_SB(struct super_block *sb)
+{
+        return sb->s_fs_info;
+}
+
+static inline struct pohmelfs_inode *POHMELFS_I(struct inode *inode)
+{
+        return container_of(inode, struct pohmelfs_inode, vfs_inode);
+}
+
+static inline u64 pohmelfs_new_ino(struct pohmelfs_sb *psb)
+{
+        u64 ino;
+
+        spin_lock(&psb->ino_lock);
+        ino = psb->ino++;
+        spin_unlock(&psb->ino_lock);
+
+        return ino;
+}
+
+static inline void pohmelfs_put_inode(struct pohmelfs_inode *pi)
+{
+        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);
+
+        spin_lock(&psb->ino_lock);
+        list_move_tail(&pi->inode_entry, &psb->drop_list);
+        pi->drop_count++;
+        spin_unlock(&psb->ino_lock);
+}
+
+struct pohmelfs_config {
+        struct list_head        config_entry;
+
+        struct netfs_state      state;
+};
+
+struct pohmelfs_config_group {
+        /*
+         * Entry in the global config group list.
+         */
+        struct list_head        group_entry;
+
+        /*
+         * Index of the current group.
+         */
+        unsigned int            idx;
+        /*
+         * Number of config_list entries in this group entry.
+         */
+        unsigned int            num_entry;
+        /*
+         * Algorithm strings.
+         */
+        char                    *hash_string;
+        char                    *cipher_string;
+
+        /*
+         * Algorithm string lengths.
+         */
+        unsigned int            hash_strlen;
+        unsigned int            cipher_strlen;
+
+        /*
+         * Key and its size.
+         */
+        unsigned int            hash_keysize;
+        unsigned int            cipher_keysize;
+        u8                      *hash_key;
+        u8                      *cipher_key;
+
+        /*
+         * List of config entries (network state info) for given idx.
+         */
+        struct list_head        config_list;
+};
+
+int __init pohmelfs_config_init(void);
+void pohmelfs_config_exit(void);
+int pohmelfs_copy_config(struct pohmelfs_sb *psb);
+int pohmelfs_copy_crypto(struct pohmelfs_sb *psb);
+int pohmelfs_config_check(struct pohmelfs_config *config, int idx);
+int pohmelfs_state_init_one(struct pohmelfs_sb *psb, struct pohmelfs_config *conf);
+
+extern const struct file_operations pohmelfs_dir_fops;
+extern const struct inode_operations pohmelfs_dir_inode_ops;
+
+int pohmelfs_state_init(struct pohmelfs_sb *psb);
+void pohmelfs_state_exit(struct pohmelfs_sb *psb);
+void pohmelfs_state_flush_transactions(struct netfs_state *st);
+
+void pohmelfs_fill_inode(struct inode *inode, struct netfs_inode_info *info);
+
+void pohmelfs_name_del(struct pohmelfs_inode *parent, struct pohmelfs_name *n);
+void pohmelfs_free_names(struct pohmelfs_inode *parent);
+struct pohmelfs_name *pohmelfs_search_hash(struct pohmelfs_inode *pi, u32 hash);
+
+void pohmelfs_inode_del_inode(struct pohmelfs_sb *psb, struct pohmelfs_inode *pi);
+
+struct pohmelfs_inode *pohmelfs_create_entry_local(struct pohmelfs_sb *psb,
+        struct pohmelfs_inode *parent, struct qstr *str, u64 start, int mode);
+
+int pohmelfs_write_create_inode(struct pohmelfs_inode *pi);
+
+int pohmelfs_write_inode_create(struct inode *inode, struct netfs_trans *trans);
+int pohmelfs_remove_child(struct pohmelfs_inode *parent, struct pohmelfs_name *n);
+
+struct pohmelfs_inode *pohmelfs_new_inode(struct pohmelfs_sb *psb,
+                struct pohmelfs_inode *parent, struct qstr *str,
+                struct netfs_inode_info *info, int link);
+
+int pohmelfs_setattr(struct dentry *dentry, struct iattr *attr);
+int pohmelfs_setattr_raw(struct inode *inode, struct iattr *attr);
+
+int pohmelfs_meta_command(struct pohmelfs_inode *pi, unsigned int cmd_op, unsigned int flags,
+                netfs_trans_complete_t complete, void *priv, u64 start);
+int pohmelfs_meta_command_data(struct pohmelfs_inode *pi, u64 id, unsigned int cmd_op, char *addon,
+                unsigned int flags, netfs_trans_complete_t complete, void *priv, u64 start);
+
+void pohmelfs_check_states(struct pohmelfs_sb *psb);
+void pohmelfs_switch_active(struct pohmelfs_sb *psb);
+
+int pohmelfs_construct_path_string(struct pohmelfs_inode *pi, void *data, int len);
+int pohmelfs_path_length(struct pohmelfs_inode *pi);
+
+struct pohmelfs_crypto_completion {
+        struct completion       complete;
+        int                     error;
+};
+
+int pohmelfs_trans_crypt(struct netfs_trans *t, struct pohmelfs_sb *psb);
+void pohmelfs_crypto_exit(struct pohmelfs_sb *psb);
+int pohmelfs_crypto_init(struct pohmelfs_sb *psb);
+
+int pohmelfs_crypto_engine_init(struct pohmelfs_crypto_engine *e, struct pohmelfs_sb *psb);
+void pohmelfs_crypto_engine_exit(struct pohmelfs_crypto_engine *e);
+
+int pohmelfs_crypto_process_input_data(struct pohmelfs_crypto_engine *e, u64 iv,
+                void *data, struct page *page, unsigned int size);
+int pohmelfs_crypto_process_input_page(struct pohmelfs_crypto_engine *e,
+                struct page *page, unsigned int size, u64 iv);
+
+static inline u64 pohmelfs_gen_iv(struct netfs_trans *t)
+{
+        u64 iv = t->gen;
+
+        iv <<= 32;
+        iv |= ((unsigned long)t) & 0xffffffff;
+
+        return iv;
+}
+
+int pohmelfs_data_lock(struct pohmelfs_inode *pi, u64 start, u32 size, int type);
+int pohmelfs_data_unlock(struct pohmelfs_inode *pi, u64 start, u32 size, int type);
+int pohmelfs_data_lock_response(struct netfs_state *st);
+
+static inline int pohmelfs_need_lock(struct pohmelfs_inode *pi, int type)
+{
+        if (test_bit(NETFS_INODE_OWNED, &pi->state)) {
+                if (type == pi->lock_type)
+                        return 0;
+                if ((type == POHMELFS_READ_LOCK) && (pi->lock_type == POHMELFS_WRITE_LOCK))
+                        return 0;
+        }
+
+        if (!test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state))
+                return 0;
+
+        return 1;
+}
+
+int __init pohmelfs_mcache_init(void);
+void pohmelfs_mcache_exit(void);
+
+/* #define CONFIG_POHMELFS_DEBUG */
+
+#ifdef CONFIG_POHMELFS_DEBUG
+#define dprintka(f, a...) printk(f, ##a)
+#define dprintk(f, a...) printk("%d: " f, task_pid_vnr(current), ##a)
+#else
+#define dprintka(f, a...) do {} while (0)
+#define dprintk(f, a...) do {} while (0)
+#endif
+
+static inline void netfs_trans_get(struct netfs_trans *t)
+{
+        atomic_inc(&t->refcnt);
+}
+
+static inline void netfs_trans_put(struct netfs_trans *t)
+{
+        if (atomic_dec_and_test(&t->refcnt)) {
+                dprintk("%s: t: %p, gen: %u, err: %d.\n",
+                        __func__, t, t->gen, t->result);
+                if (t->complete)
+                        t->complete(t->pages, t->page_num,
+                                t->private, t->result);
+                netfs_trans_free(t);
+        }
+}
+
+struct pohmelfs_mcache {
+        struct rb_node                  mcache_entry;
+        struct completion               complete;
+
+        atomic_t                        refcnt;
+
+        u64                             gen;
+
+        void                            *data;
+        u64                             start;
+        u32                             size;
+        int                             err;
+
+        struct netfs_inode_info         info;
+};
+
+struct pohmelfs_mcache *pohmelfs_mcache_alloc(struct pohmelfs_sb *psb, u64 start,
+                unsigned int size, void *data);
+void pohmelfs_mcache_free(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m);
+struct pohmelfs_mcache *pohmelfs_mcache_search(struct pohmelfs_sb *psb, u64 gen);
+void pohmelfs_mcache_remove_locked(struct pohmelfs_sb *psb, struct pohmelfs_mcache *m);
+
+static inline void pohmelfs_mcache_get(struct pohmelfs_mcache *m)
+{
+        atomic_inc(&m->refcnt);
+}
+
+static inline void pohmelfs_mcache_put(struct pohmelfs_sb *psb,
+                struct pohmelfs_mcache *m)
+{
+        if (atomic_dec_and_test(&m->refcnt))
+                pohmelfs_mcache_free(psb, m);
+}
+
+/*#define POHMELFS_TRUNCATE_ON_INODE_FLUSH
+ */
+
+#endif /* __KERNEL__*/
+
+#endif /* __NETFS_H */
diff --git a/drivers/staging/pohmelfs/path_entry.c b/drivers/staging/pohmelfs/path_entry.c
new file mode 100644
index 00000000000..400a9fc386a
--- /dev/null
+++ b/drivers/staging/pohmelfs/path_entry.c
@@ -0,0 +1,120 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/ktime.h>
+#include <linux/fs_struct.h>
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/mount.h>
+#include <linux/mm.h>
+
+#include "netfs.h"
+
+#define UNHASHED_OBSCURE_STRING_SIZE            sizeof(" (deleted)")
+
+/*
+ * Create path from root for given inode.
+ * Path is formed as set of stuctures, containing name of the object
+ * and its inode data (mode, permissions and so on).
+ */
+int pohmelfs_construct_path_string(struct pohmelfs_inode *pi, void *data, int len)
+{
+        struct path path;
+        struct dentry *d;
+        char *ptr;
+        int err = 0, strlen, reduce = 0;
+
+        d = d_find_alias(&pi->vfs_inode);
+        if (!d) {
+                printk("%s: no alias, list_empty: %d.\n", __func__, list_empty(&pi->vfs_inode.i_dentry));
+                return -ENOENT;
+        }
+
+        spin_lock(&current->fs->lock);
+        path.mnt = mntget(current->fs->root.mnt);
+        spin_unlock(&current->fs->lock);
+
+        path.dentry = d;
+
+        if (!IS_ROOT(d) && d_unhashed(d))
+                reduce = 1;
+
+        ptr = d_path(&path, data, len);
+        if (IS_ERR(ptr)) {
+                err = PTR_ERR(ptr);
+                goto out;
+        }
+
+        if (reduce && len >= UNHASHED_OBSCURE_STRING_SIZE) {
+                char *end = data + len - UNHASHED_OBSCURE_STRING_SIZE;
+                *end = '\0';
+        }
+
+        strlen = len - (ptr - (char *)data);
+        memmove(data, ptr, strlen);
+        ptr = data;
+
+        err = strlen;
+
+        dprintk("%s: dname: '%s', len: %u, maxlen: %u, name: '%s', strlen: %d.\n",
+                        __func__, d->d_name.name, d->d_name.len, len, ptr, strlen);
+
+out:
+        dput(d);
+        mntput(path.mnt);
+
+        return err;
+}
+
+int pohmelfs_path_length(struct pohmelfs_inode *pi)
+{
+        struct dentry *d, *root, *first;
+        int len;
+        unsigned seq;
+
+        first = d_find_alias(&pi->vfs_inode);
+        if (!first) {
+                dprintk("%s: ino: %llu, mode: %o.\n", __func__, pi->ino, pi->vfs_inode.i_mode);
+                return -ENOENT;
+        }
+
+        spin_lock(&current->fs->lock);
+        root = dget(current->fs->root.dentry);
+        spin_unlock(&current->fs->lock);
+
+rename_retry:
+        len = 1; /* Root slash */
+        d = first;
+        seq = read_seqbegin(&rename_lock);
+        rcu_read_lock();
+
+        if (!IS_ROOT(d) && d_unhashed(d))
+                len += UNHASHED_OBSCURE_STRING_SIZE; /* Obscure " (deleted)" string */
+
+        while (d && d != root && !IS_ROOT(d)) {
+                len += d->d_name.len + 1; /* Plus slash */
+                d = d->d_parent;
+        }
+        rcu_read_unlock();
+        if (read_seqretry(&rename_lock, seq))
+                goto rename_retry;
+
+        dput(root);
+        dput(first);
+
+        return len + 1; /* Including zero-byte */
+}
diff --git a/drivers/staging/pohmelfs/trans.c b/drivers/staging/pohmelfs/trans.c
new file mode 100644
index 00000000000..36a25358256
--- /dev/null
+++ b/drivers/staging/pohmelfs/trans.c
@@ -0,0 +1,706 @@
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/crypto.h>
+#include <linux/fs.h>
+#include <linux/jhash.h>
+#include <linux/hash.h>
+#include <linux/ktime.h>
+#include <linux/mempool.h>
+#include <linux/mm.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/parser.h>
+#include <linux/poll.h>
+#include <linux/swap.h>
+#include <linux/slab.h>
+#include <linux/statfs.h>
+#include <linux/writeback.h>
+
+#include "netfs.h"
+
+static struct kmem_cache *netfs_trans_dst;
+static mempool_t *netfs_trans_dst_pool;
+
+static void netfs_trans_init_static(struct netfs_trans *t, int num, int size)
+{
+        t->page_num = num;
+        t->total_size = size;
+        atomic_set(&t->refcnt, 1);
+
+        spin_lock_init(&t->dst_lock);
+        INIT_LIST_HEAD(&t->dst_list);
+}
+
+static int netfs_trans_send_pages(struct netfs_trans *t, struct netfs_state *st)
+{
+        int err = 0;
+        unsigned int i, attached_pages = t->attached_pages, ci;
+        struct msghdr msg;
+        struct page **pages = (t->eng)?t->eng->pages:t->pages;
+        struct page *p;
+        unsigned int size;
+
+        msg.msg_name = NULL;
+        msg.msg_namelen = 0;
+        msg.msg_control = NULL;
+        msg.msg_controllen = 0;
+        msg.msg_flags = MSG_WAITALL | MSG_MORE;
+
+        ci = 0;
+        for (i=0; i<t->page_num; ++i) {
+                struct page *page = pages[ci];
+                struct netfs_cmd cmd;
+                struct iovec io;
+
+                p = t->pages[i];
+
+                if (!p)
+                        continue;
+
+                size = page_private(p);
+
+                io.iov_base = &cmd;
+                io.iov_len = sizeof(struct netfs_cmd);
+
+                cmd.cmd = NETFS_WRITE_PAGE;
+                cmd.ext = 0;
+                cmd.id = 0;
+                cmd.size = size;
+                cmd.start = p->index;
+                cmd.start <<= PAGE_CACHE_SHIFT;
+                cmd.csize = 0;
+                cmd.cpad = 0;
+                cmd.iv = pohmelfs_gen_iv(t);
+
+                netfs_convert_cmd(&cmd);
+
+                msg.msg_iov = &io;
+                msg.msg_iovlen = 1;
+                msg.msg_flags = MSG_WAITALL | MSG_MORE;
+
+                err = kernel_sendmsg(st->socket, &msg, (struct kvec *)msg.msg_iov, 1, sizeof(struct netfs_cmd));
+                if (err <= 0) {
+                        printk("%s: %d/%d failed to send transaction header: t: %p, gen: %u, err: %d.\n",
+                                        __func__, i, t->page_num, t, t->gen, err);
+                        if (err == 0)
+                                err = -ECONNRESET;
+                        goto err_out;
+                }
+
+                msg.msg_flags = MSG_WAITALL | (attached_pages == 1 ? 0 :
+                                MSG_MORE);
+
+                err = kernel_sendpage(st->socket, page, 0, size, msg.msg_flags);
+                if (err <= 0) {
+                        printk("%s: %d/%d failed to send transaction page: t: %p, gen: %u, size: %u, err: %d.\n",
+                                        __func__, i, t->page_num, t, t->gen, size, err);
+                        if (err == 0)
+                                err = -ECONNRESET;
+                        goto err_out;
+                }
+
+                dprintk("%s: %d/%d sent t: %p, gen: %u, page: %p/%p, size: %u.\n",
+                        __func__, i, t->page_num, t, t->gen, page, p, size);
+
+                err = 0;
+                attached_pages--;
+                if (!attached_pages)
+                        break;
+                ci++;
+
+                continue;
+
+err_out:
+                printk("%s: t: %p, gen: %u, err: %d.\n", __func__, t, t->gen, err);
+                netfs_state_exit(st);
+                break;
+        }
+
+        return err;
+}
+
+int netfs_trans_send(struct netfs_trans *t, struct netfs_state *st)
+{
+        int err;
+        struct msghdr msg;
+
+        BUG_ON(!t->iovec.iov_len);
+        BUG_ON(t->iovec.iov_len > 1024*1024*1024);
+
+        netfs_state_lock_send(st);
+        if (!st->socket) {
+                err = netfs_state_init(st);
+                if (err)
+                        goto err_out_unlock_return;
+        }
+
+        msg.msg_iov = &t->iovec;
+        msg.msg_iovlen = 1;
+        msg.msg_name = NULL;
+        msg.msg_namelen = 0;
+        msg.msg_control = NULL;
+        msg.msg_controllen = 0;
+        msg.msg_flags = MSG_WAITALL;
+
+        if (t->attached_pages)
+                msg.msg_flags |= MSG_MORE;
+
+        err = kernel_sendmsg(st->socket, &msg, (struct kvec *)msg.msg_iov, 1, t->iovec.iov_len);
+        if (err <= 0) {
+                printk("%s: failed to send contig transaction: t: %p, gen: %u, size: %zu, err: %d.\n",
+                                __func__, t, t->gen, t->iovec.iov_len, err);
+                if (err == 0)
+                        err = -ECONNRESET;
+                goto err_out_unlock_return;
+        }
+
+        dprintk("%s: sent %s transaction: t: %p, gen: %u, size: %zu, page_num: %u.\n",
+                        __func__, (t->page_num)?"partial":"full",
+                        t, t->gen, t->iovec.iov_len, t->page_num);
+
+        err = 0;
+        if (t->attached_pages)
+                err = netfs_trans_send_pages(t, st);
+
+err_out_unlock_return:
+
+        if (st->need_reset)
+                netfs_state_exit(st);
+
+        netfs_state_unlock_send(st);
+
+        dprintk("%s: t: %p, gen: %u, err: %d.\n",
+                __func__, t, t->gen, err);
+
+        t->result = err;
+        return err;
+}
+
+static inline int netfs_trans_cmp(unsigned int gen, unsigned int new)
+{
+        if (gen < new)
+                return 1;
+        if (gen > new)
+                return -1;
+        return 0;
+}
+
+struct netfs_trans_dst *netfs_trans_search(struct netfs_state *st, unsigned int gen)
+{
+        struct rb_root *root = &st->trans_root;
+        struct rb_node *n = root->rb_node;
+        struct netfs_trans_dst *tmp, *ret = NULL;
+        struct netfs_trans *t;
+        int cmp;
+
+        while (n) {
+                tmp = rb_entry(n, struct netfs_trans_dst, state_entry);
+                t = tmp->trans;
+
+                cmp = netfs_trans_cmp(t->gen, gen);
+                if (cmp < 0)
+                        n = n->rb_left;
+                else if (cmp > 0)
+                        n = n->rb_right;
+                else {
+                        ret = tmp;
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+static int netfs_trans_insert(struct netfs_trans_dst *ndst, struct netfs_state *st)
+{
+        struct rb_root *root = &st->trans_root;
+        struct rb_node **n = &root->rb_node, *parent = NULL;
+        struct netfs_trans_dst *ret = NULL, *tmp;
+        struct netfs_trans *t = NULL, *new = ndst->trans;
+        int cmp;
+
+        while (*n) {
+                parent = *n;
+
+                tmp = rb_entry(parent, struct netfs_trans_dst, state_entry);
+                t = tmp->trans;
+
+                cmp = netfs_trans_cmp(t->gen, new->gen);
+                if (cmp < 0)
+                        n = &parent->rb_left;
+                else if (cmp > 0)
+                        n = &parent->rb_right;
+                else {
+                        ret = tmp;
+                        break;
+                }
+        }
+
+        if (ret) {
+                printk("%s: exist: old: gen: %u, flags: %x, send_time: %lu, "
+                                "new: gen: %u, flags: %x, send_time: %lu.\n",
+                        __func__, t->gen, t->flags, ret->send_time,
+                        new->gen, new->flags, ndst->send_time);
+                return -EEXIST;
+        }
+
+        rb_link_node(&ndst->state_entry, parent, n);
+        rb_insert_color(&ndst->state_entry, root);
+        ndst->send_time = jiffies;
+
+        return 0;
+}
+
+int netfs_trans_remove_nolock(struct netfs_trans_dst *dst, struct netfs_state *st)
+{
+        if (dst && dst->state_entry.rb_parent_color) {
+                rb_erase(&dst->state_entry, &st->trans_root);
+                dst->state_entry.rb_parent_color = 0;
+                return 1;
+        }
+        return 0;
+}
+
+static int netfs_trans_remove_state(struct netfs_trans_dst *dst)
+{
+        int ret;
+        struct netfs_state *st = dst->state;
+
+        mutex_lock(&st->trans_lock);
+        ret = netfs_trans_remove_nolock(dst, st);
+        mutex_unlock(&st->trans_lock);
+
+        return ret;
+}
+
+/*
+ * Create new destination for given transaction associated with given network state.
+ * Transaction's reference counter is bumped and will be dropped when either
+ * reply is received or when async timeout detection task will fail resending
+ * and drop transaction.
+ */
+static int netfs_trans_push_dst(struct netfs_trans *t, struct netfs_state *st)
+{
+        struct netfs_trans_dst *dst;
+        int err;
+
+        dst = mempool_alloc(netfs_trans_dst_pool, GFP_KERNEL);
+        if (!dst)
+                return -ENOMEM;
+
+        dst->retries = 0;
+        dst->send_time = 0;
+        dst->state = st;
+        dst->trans = t;
+        netfs_trans_get(t);
+
+        mutex_lock(&st->trans_lock);
+        err = netfs_trans_insert(dst, st);
+        mutex_unlock(&st->trans_lock);
+
+        if (err)
+                goto err_out_free;
+
+        spin_lock(&t->dst_lock);
+        list_add_tail(&dst->trans_entry, &t->dst_list);
+        spin_unlock(&t->dst_lock);
+
+        return 0;
+
+err_out_free:
+        t->result = err;
+        netfs_trans_put(t);
+        mempool_free(dst, netfs_trans_dst_pool);
+        return err;
+}
+
+static void netfs_trans_free_dst(struct netfs_trans_dst *dst)
+{
+        netfs_trans_put(dst->trans);
+        mempool_free(dst, netfs_trans_dst_pool);
+}
+
+static void netfs_trans_remove_dst(struct netfs_trans_dst *dst)
+{
+        if (netfs_trans_remove_state(dst))
+                netfs_trans_free_dst(dst);
+}
+
+/*
+ * Drop destination transaction entry when we know it.
+ */
+void netfs_trans_drop_dst(struct netfs_trans_dst *dst)
+{
+        struct netfs_trans *t = dst->trans;
+
+        spin_lock(&t->dst_lock);
+        list_del_init(&dst->trans_entry);
+        spin_unlock(&t->dst_lock);
+
+        netfs_trans_remove_dst(dst);
+}
+
+/*
+ * Drop destination transaction entry when we know it and when we
+ * already removed dst from state tree.
+ */
+void netfs_trans_drop_dst_nostate(struct netfs_trans_dst *dst)
+{
+        struct netfs_trans *t = dst->trans;
+
+        spin_lock(&t->dst_lock);
+        list_del_init(&dst->trans_entry);
+        spin_unlock(&t->dst_lock);
+
+        netfs_trans_free_dst(dst);
+}
+
+/*
+ * This drops destination transaction entry from appropriate network state
+ * tree and drops related reference counter. It is possible that transaction
+ * will be freed here if its reference counter hits zero.
+ * Destination transaction entry will be freed.
+ */
+void netfs_trans_drop_trans(struct netfs_trans *t, struct netfs_state *st)
+{
+        struct netfs_trans_dst *dst, *tmp, *ret = NULL;
+
+        spin_lock(&t->dst_lock);
+        list_for_each_entry_safe(dst, tmp, &t->dst_list, trans_entry) {
+                if (dst->state == st) {
+                        ret = dst;
+                        list_del(&dst->trans_entry);
+                        break;
+                }
+        }
+        spin_unlock(&t->dst_lock);
+
+        if (ret)
+                netfs_trans_remove_dst(ret);
+}
+
+/*
+ * This drops destination transaction entry from appropriate network state
+ * tree and drops related reference counter. It is possible that transaction
+ * will be freed here if its reference counter hits zero.
+ * Destination transaction entry will be freed.
+ */
+void netfs_trans_drop_last(struct netfs_trans *t, struct netfs_state *st)
+{
+        struct netfs_trans_dst *dst, *tmp, *ret;
+
+        spin_lock(&t->dst_lock);
+        ret = list_entry(t->dst_list.prev, struct netfs_trans_dst, trans_entry);
+        if (ret->state != st) {
+                ret = NULL;
+                list_for_each_entry_safe(dst, tmp, &t->dst_list, trans_entry) {
+                        if (dst->state == st) {
+                                ret = dst;
+                                list_del_init(&dst->trans_entry);
+                                break;
+                        }
+                }
+        } else {
+                list_del(&ret->trans_entry);
+        }
+        spin_unlock(&t->dst_lock);
+
+        if (ret)
+                netfs_trans_remove_dst(ret);
+}
+
+static int netfs_trans_push(struct netfs_trans *t, struct netfs_state *st)
+{
+        int err;
+
+        err = netfs_trans_push_dst(t, st);
+        if (err)
+                return err;
+
+        err = netfs_trans_send(t, st);
+        if (err)
+                goto err_out_free;
+
+        if (t->flags & NETFS_TRANS_SINGLE_DST)
+                pohmelfs_switch_active(st->psb);
+
+        return 0;
+
+err_out_free:
+        t->result = err;
+        netfs_trans_drop_last(t, st);
+
+        return err;
+}
+
+int netfs_trans_finish_send(struct netfs_trans *t, struct pohmelfs_sb *psb)
+{
+        struct pohmelfs_config *c;
+        int err = -ENODEV;
+        struct netfs_state *st;
+#if 0
+        dprintk("%s: t: %p, gen: %u, size: %u, page_num: %u, active: %p.\n",
+                __func__, t, t->gen, t->iovec.iov_len, t->page_num, psb->active_state);
+#endif
+        mutex_lock(&psb->state_lock);
+        list_for_each_entry(c, &psb->state_list, config_entry) {
+                st = &c->state;
+
+                if (t->flags & NETFS_TRANS_SINGLE_DST) {
+                        if (!(st->ctl.perm & POHMELFS_IO_PERM_READ))
+                                continue;
+                } else {
+                        if (!(st->ctl.perm & POHMELFS_IO_PERM_WRITE))
+                                continue;
+                }
+
+                if (psb->active_state && (psb->active_state->state.ctl.prio >= st->ctl.prio) &&
+                                (t->flags & NETFS_TRANS_SINGLE_DST))
+                        st = &psb->active_state->state;
+
+                err = netfs_trans_push(t, st);
+                if (!err && (t->flags & NETFS_TRANS_SINGLE_DST))
+                        break;
+        }
+
+        mutex_unlock(&psb->state_lock);
+#if 0
+        dprintk("%s: fully sent t: %p, gen: %u, size: %u, page_num: %u, err: %d.\n",
+                __func__, t, t->gen, t->iovec.iov_len, t->page_num, err);
+#endif
+        if (err)
+                t->result = err;
+        return err;
+}
+
+int netfs_trans_finish(struct netfs_trans *t, struct pohmelfs_sb *psb)
+{
+        int err;
+        struct netfs_cmd *cmd = t->iovec.iov_base;
+
+        t->gen = atomic_inc_return(&psb->trans_gen);
+
+        cmd->size = t->iovec.iov_len - sizeof(struct netfs_cmd) +
+                t->attached_size + t->attached_pages * sizeof(struct netfs_cmd);
+        cmd->cmd = NETFS_TRANS;
+        cmd->start = t->gen;
+        cmd->id = 0;
+
+        if (psb->perform_crypto) {
+                cmd->ext = psb->crypto_attached_size;
+                cmd->csize = psb->crypto_attached_size;
+        }
+
+        dprintk("%s: t: %u, size: %u, iov_len: %zu, attached_size: %u, attached_pages: %u.\n",
+                        __func__, t->gen, cmd->size, t->iovec.iov_len, t->attached_size, t->attached_pages);
+        err = pohmelfs_trans_crypt(t, psb);
+        if (err) {
+                t->result = err;
+                netfs_convert_cmd(cmd);
+                dprintk("%s: trans: %llu, crypto_attached_size: %u, attached_size: %u, attached_pages: %d, trans_size: %u, err: %d.\n",
+                        __func__, cmd->start, psb->crypto_attached_size, t->attached_size, t->attached_pages, cmd->size, err);
+        }
+        netfs_trans_put(t);
+        return err;
+}
+
+/*
+ * Resend transaction to remote server(s).
+ * If new servers were added into superblock, we can try to send data
+ * to them too.
+ *
+ * It is called under superblock's state_lock, so we can safely
+ * dereference psb->state_list. Also, transaction's reference counter is
+ * bumped, so it can not go away under us, thus we can safely access all
+ * its members. State is locked.
+ *
+ * This function returns 0 if transaction was successfully sent to at
+ * least one destination target.
+ */
+int netfs_trans_resend(struct netfs_trans *t, struct pohmelfs_sb *psb)
+{
+        struct netfs_trans_dst *dst;
+        struct netfs_state *st;
+        struct pohmelfs_config *c;
+        int err, exist, error = -ENODEV;
+
+        list_for_each_entry(c, &psb->state_list, config_entry) {
+                st = &c->state;
+
+                exist = 0;
+                spin_lock(&t->dst_lock);
+                list_for_each_entry(dst, &t->dst_list, trans_entry) {
+                        if (st == dst->state) {
+                                exist = 1;
+                                break;
+                        }
+                }
+                spin_unlock(&t->dst_lock);
+
+                if (exist) {
+                        if (!(t->flags & NETFS_TRANS_SINGLE_DST) ||
+                                        (c->config_entry.next == &psb->state_list)) {
+                                dprintk("%s: resending st: %p, t: %p, gen: %u.\n",
+                                                __func__, st, t, t->gen);
+                                err = netfs_trans_send(t, st);
+                                if (!err)
+                                        error = 0;
+                        }
+                        continue;
+                }
+
+                dprintk("%s: pushing/resending st: %p, t: %p, gen: %u.\n",
+                                __func__, st, t, t->gen);
+                err = netfs_trans_push(t, st);
+                if (err)
+                        continue;
+                error = 0;
+                if (t->flags & NETFS_TRANS_SINGLE_DST)
+                        break;
+        }
+
+        t->result = error;
+        return error;
+}
+
+void *netfs_trans_add(struct netfs_trans *t, unsigned int size)
+{
+        struct iovec *io = &t->iovec;
+        void *ptr;
+
+        if (size > t->total_size) {
+                ptr = ERR_PTR(-EINVAL);
+                goto out;
+        }
+
+        if (io->iov_len + size > t->total_size) {
+                dprintk("%s: too big size t: %p, gen: %u, iov_len: %zu, size: %u, total: %u.\n",
+                                __func__, t, t->gen, io->iov_len, size, t->total_size);
+                ptr = ERR_PTR(-E2BIG);
+                goto out;
+        }
+
+        ptr = io->iov_base + io->iov_len;
+        io->iov_len += size;
+
+out:
+        dprintk("%s: t: %p, gen: %u, size: %u, total: %zu.\n",
+                __func__, t, t->gen, size, io->iov_len);
+        return ptr;
+}
+
+void netfs_trans_free(struct netfs_trans *t)
+{
+        if (t->eng)
+                pohmelfs_crypto_thread_make_ready(t->eng->thread);
+        kfree(t);
+}
+
+struct netfs_trans *netfs_trans_alloc(struct pohmelfs_sb *psb, unsigned int size,
+                unsigned int flags, unsigned int nr)
+{
+        struct netfs_trans *t;
+        unsigned int num, cont, pad, size_no_trans;
+        unsigned int crypto_added = 0;
+        struct netfs_cmd *cmd;
+
+        if (psb->perform_crypto)
+                crypto_added = psb->crypto_attached_size;
+
+        /*
+         * |sizeof(struct netfs_trans)|
+         * |sizeof(struct netfs_cmd)| - transaction header
+         * |size| - buffer with requested size
+         * |padding| - crypto padding, zero bytes
+         * |nr * sizeof(struct page *)| - array of page pointers
+         *
+         * Overall size should be less than PAGE_SIZE for guaranteed allocation.
+         */
+
+        cont = size;
+        size = ALIGN(size, psb->crypto_align_size);
+        pad = size - cont;
+
+        size_no_trans = size + sizeof(struct netfs_cmd) * 2 + crypto_added;
+
+        cont = sizeof(struct netfs_trans) + size_no_trans;
+
+        num = (PAGE_SIZE - cont)/sizeof(struct page *);
+
+        if (nr > num)
+                nr = num;
+
+        t = kzalloc(cont + nr*sizeof(struct page *), GFP_NOIO);
+        if (!t)
+                goto err_out_exit;
+
+        t->iovec.iov_base = (void *)(t + 1);
+        t->pages = (struct page **)(t->iovec.iov_base + size_no_trans);
+
+        /*
+         * Reserving space for transaction header.
+         */
+        t->iovec.iov_len = sizeof(struct netfs_cmd) + crypto_added;
+
+        netfs_trans_init_static(t, nr, size_no_trans);
+
+        t->flags = flags;
+        t->psb = psb;
+
+        cmd = (struct netfs_cmd *)t->iovec.iov_base;
+
+        cmd->size = size;
+        cmd->cpad = pad;
+        cmd->csize = crypto_added;
+
+        dprintk("%s: t: %p, gen: %u, size: %u, padding: %u, align_size: %u, flags: %x, "
+                        "page_num: %u, base: %p, pages: %p.\n",
+                        __func__, t, t->gen, size, pad, psb->crypto_align_size, flags, nr,
+                        t->iovec.iov_base, t->pages);
+
+        return t;
+
+err_out_exit:
+        return NULL;
+}
+
+int netfs_trans_init(void)
+{
+        int err = -ENOMEM;
+
+        netfs_trans_dst = kmem_cache_create("netfs_trans_dst", sizeof(struct netfs_trans_dst),
+                        0, 0, NULL);
+        if (!netfs_trans_dst)
+                goto err_out_exit;
+
+        netfs_trans_dst_pool = mempool_create_slab_pool(256, netfs_trans_dst);
+        if (!netfs_trans_dst_pool)
+                goto err_out_free;
+
+        return 0;
+
+err_out_free:
+        kmem_cache_destroy(netfs_trans_dst);
+err_out_exit:
+        return err;
+}
+
+void netfs_trans_exit(void)
+{
+        mempool_destroy(netfs_trans_dst_pool);
+        kmem_cache_destroy(netfs_trans_dst);
+}