1 files changed, 449 insertions, 0 deletions

diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
new file mode 100644
index 000000000000..1e962348d111
--- /dev/null
+++ b/fs/cachefiles/interface.c
@@ -0,0 +1,449 @@
+/* FS-Cache interface to CacheFiles
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/mount.h>
+#include <linux/buffer_head.h>
+#include "internal.h"
+
+#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
+
+struct cachefiles_lookup_data {
+        struct cachefiles_xattr *auxdata;       /* auxiliary data */
+        char                    *key;           /* key path */
+};
+
+static int cachefiles_attr_changed(struct fscache_object *_object);
+
+/*
+ * allocate an object record for a cookie lookup and prepare the lookup data
+ */
+static struct fscache_object *cachefiles_alloc_object(
+        struct fscache_cache *_cache,
+        struct fscache_cookie *cookie)
+{
+        struct cachefiles_lookup_data *lookup_data;
+        struct cachefiles_object *object;
+        struct cachefiles_cache *cache;
+        struct cachefiles_xattr *auxdata;
+        unsigned keylen, auxlen;
+        void *buffer;
+        char *key;
+
+        cache = container_of(_cache, struct cachefiles_cache, cache);
+
+        _enter("{%s},%p,", cache->cache.identifier, cookie);
+
+        lookup_data = kmalloc(sizeof(*lookup_data), GFP_KERNEL);
+        if (!lookup_data)
+                goto nomem_lookup_data;
+
+        /* create a new object record and a temporary leaf image */
+        object = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
+        if (!object)
+                goto nomem_object;
+
+        ASSERTCMP(object->backer, ==, NULL);
+
+        BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
+        atomic_set(&object->usage, 1);
+
+        fscache_object_init(&object->fscache, cookie, &cache->cache);
+
+        object->type = cookie->def->type;
+
+        /* get hold of the raw key
+         * - stick the length on the front and leave space on the back for the
+         *   encoder
+         */
+        buffer = kmalloc((2 + 512) + 3, GFP_KERNEL);
+        if (!buffer)
+                goto nomem_buffer;
+
+        keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512);
+        ASSERTCMP(keylen, <, 512);
+
+        *(uint16_t *)buffer = keylen;
+        ((char *)buffer)[keylen + 2] = 0;
+        ((char *)buffer)[keylen + 3] = 0;
+        ((char *)buffer)[keylen + 4] = 0;
+
+        /* turn the raw key into something that can work with as a filename */
+        key = cachefiles_cook_key(buffer, keylen + 2, object->type);
+        if (!key)
+                goto nomem_key;
+
+        /* get hold of the auxiliary data and prepend the object type */
+        auxdata = buffer;
+        auxlen = 0;
+        if (cookie->def->get_aux) {
+                auxlen = cookie->def->get_aux(cookie->netfs_data,
+                                              auxdata->data, 511);
+                ASSERTCMP(auxlen, <, 511);
+        }
+
+        auxdata->len = auxlen + 1;
+        auxdata->type = cookie->def->type;
+
+        lookup_data->auxdata = auxdata;
+        lookup_data->key = key;
+        object->lookup_data = lookup_data;
+
+        _leave(" = %p [%p]", &object->fscache, lookup_data);
+        return &object->fscache;
+
+nomem_key:
+        kfree(buffer);
+nomem_buffer:
+        BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
+        kmem_cache_free(cachefiles_object_jar, object);
+        fscache_object_destroyed(&cache->cache);
+nomem_object:
+        kfree(lookup_data);
+nomem_lookup_data:
+        _leave(" = -ENOMEM");
+        return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * attempt to look up the nominated node in this cache
+ */
+static void cachefiles_lookup_object(struct fscache_object *_object)
+{
+        struct cachefiles_lookup_data *lookup_data;
+        struct cachefiles_object *parent, *object;
+        struct cachefiles_cache *cache;
+        const struct cred *saved_cred;
+        int ret;
+
+        _enter("{OBJ%x}", _object->debug_id);
+
+        cache = container_of(_object->cache, struct cachefiles_cache, cache);
+        parent = container_of(_object->parent,
+                              struct cachefiles_object, fscache);
+        object = container_of(_object, struct cachefiles_object, fscache);
+        lookup_data = object->lookup_data;
+
+        ASSERTCMP(lookup_data, !=, NULL);
+
+        /* look up the key, creating any missing bits */
+        cachefiles_begin_secure(cache, &saved_cred);
+        ret = cachefiles_walk_to_object(parent, object,
+                                        lookup_data->key,
+                                        lookup_data->auxdata);
+        cachefiles_end_secure(cache, saved_cred);
+
+        /* polish off by setting the attributes of non-index files */
+        if (ret == 0 &&
+            object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
+                cachefiles_attr_changed(&object->fscache);
+
+        if (ret < 0) {
+                printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n",
+                       ret);
+                fscache_object_lookup_error(&object->fscache);
+        }
+
+        _leave(" [%d]", ret);
+}
+
+/*
+ * indication of lookup completion
+ */
+static void cachefiles_lookup_complete(struct fscache_object *_object)
+{
+        struct cachefiles_object *object;
+
+        object = container_of(_object, struct cachefiles_object, fscache);
+
+        _enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data);
+
+        if (object->lookup_data) {
+                kfree(object->lookup_data->key);
+                kfree(object->lookup_data->auxdata);
+                kfree(object->lookup_data);
+                object->lookup_data = NULL;
+        }
+}
+
+/*
+ * increment the usage count on an inode object (may fail if unmounting)
+ */
+static
+struct fscache_object *cachefiles_grab_object(struct fscache_object *_object)
+{
+        struct cachefiles_object *object =
+                container_of(_object, struct cachefiles_object, fscache);
+
+        _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage));
+
+#ifdef CACHEFILES_DEBUG_SLAB
+        ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
+#endif
+
+        atomic_inc(&object->usage);
+        return &object->fscache;
+}
+
+/*
+ * update the auxilliary data for an object object on disk
+ */
+static void cachefiles_update_object(struct fscache_object *_object)
+{
+        struct cachefiles_object *object;
+        struct cachefiles_xattr *auxdata;
+        struct cachefiles_cache *cache;
+        struct fscache_cookie *cookie;
+        const struct cred *saved_cred;
+        unsigned auxlen;
+
+        _enter("{OBJ%x}", _object->debug_id);
+
+        object = container_of(_object, struct cachefiles_object, fscache);
+        cache = container_of(object->fscache.cache, struct cachefiles_cache,
+                             cache);
+        cookie = object->fscache.cookie;
+
+        if (!cookie->def->get_aux) {
+                _leave(" [no aux]");
+                return;
+        }
+
+        auxdata = kmalloc(2 + 512 + 3, GFP_KERNEL);
+        if (!auxdata) {
+                _leave(" [nomem]");
+                return;
+        }
+
+        auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511);
+        ASSERTCMP(auxlen, <, 511);
+
+        auxdata->len = auxlen + 1;
+        auxdata->type = cookie->def->type;
+
+        cachefiles_begin_secure(cache, &saved_cred);
+        cachefiles_update_object_xattr(object, auxdata);
+        cachefiles_end_secure(cache, saved_cred);
+        kfree(auxdata);
+        _leave("");
+}
+
+/*
+ * discard the resources pinned by an object and effect retirement if
+ * requested
+ */
+static void cachefiles_drop_object(struct fscache_object *_object)
+{
+        struct cachefiles_object *object;
+        struct cachefiles_cache *cache;
+        const struct cred *saved_cred;
+
+        ASSERT(_object);
+
+        object = container_of(_object, struct cachefiles_object, fscache);
+
+        _enter("{OBJ%x,%d}",
+               object->fscache.debug_id, atomic_read(&object->usage));
+
+        cache = container_of(object->fscache.cache,
+                             struct cachefiles_cache, cache);
+
+#ifdef CACHEFILES_DEBUG_SLAB
+        ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
+#endif
+
+        /* delete retired objects */
+        if (object->fscache.state == FSCACHE_OBJECT_RECYCLING &&
+            _object != cache->cache.fsdef
+            ) {
+                _debug("- retire object OBJ%x", object->fscache.debug_id);
+                cachefiles_begin_secure(cache, &saved_cred);
+                cachefiles_delete_object(cache, object);
+                cachefiles_end_secure(cache, saved_cred);
+        }
+
+        /* close the filesystem stuff attached to the object */
+        if (object->backer != object->dentry)
+                dput(object->backer);
+        object->backer = NULL;
+
+        /* note that the object is now inactive */
+        if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
+                write_lock(&cache->active_lock);
+                if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE,
+                                        &object->flags))
+                        BUG();
+                rb_erase(&object->active_node, &cache->active_nodes);
+                wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
+                write_unlock(&cache->active_lock);
+        }
+
+        dput(object->dentry);
+        object->dentry = NULL;
+
+        _leave("");
+}
+
+/*
+ * dispose of a reference to an object
+ */
+static void cachefiles_put_object(struct fscache_object *_object)
+{
+        struct cachefiles_object *object;
+        struct fscache_cache *cache;
+
+        ASSERT(_object);
+
+        object = container_of(_object, struct cachefiles_object, fscache);
+
+        _enter("{OBJ%x,%d}",
+               object->fscache.debug_id, atomic_read(&object->usage));
+
+#ifdef CACHEFILES_DEBUG_SLAB
+        ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
+#endif
+
+        ASSERTIFCMP(object->fscache.parent,
+                    object->fscache.parent->n_children, >, 0);
+
+        if (atomic_dec_and_test(&object->usage)) {
+                _debug("- kill object OBJ%x", object->fscache.debug_id);
+
+                ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
+                ASSERTCMP(object->fscache.parent, ==, NULL);
+                ASSERTCMP(object->backer, ==, NULL);
+                ASSERTCMP(object->dentry, ==, NULL);
+                ASSERTCMP(object->fscache.n_ops, ==, 0);
+                ASSERTCMP(object->fscache.n_children, ==, 0);
+
+                if (object->lookup_data) {
+                        kfree(object->lookup_data->key);
+                        kfree(object->lookup_data->auxdata);
+                        kfree(object->lookup_data);
+                        object->lookup_data = NULL;
+                }
+
+                cache = object->fscache.cache;
+                kmem_cache_free(cachefiles_object_jar, object);
+                fscache_object_destroyed(cache);
+        }
+
+        _leave("");
+}
+
+/*
+ * sync a cache
+ */
+static void cachefiles_sync_cache(struct fscache_cache *_cache)
+{
+        struct cachefiles_cache *cache;
+        const struct cred *saved_cred;
+        int ret;
+
+        _enter("%p", _cache);
+
+        cache = container_of(_cache, struct cachefiles_cache, cache);
+
+        /* make sure all pages pinned by operations on behalf of the netfs are
+         * written to disc */
+        cachefiles_begin_secure(cache, &saved_cred);
+        ret = fsync_super(cache->mnt->mnt_sb);
+        cachefiles_end_secure(cache, saved_cred);
+
+        if (ret == -EIO)
+                cachefiles_io_error(cache,
+                                    "Attempt to sync backing fs superblock"
+                                    " returned error %d",
+                                    ret);
+}
+
+/*
+ * notification the attributes on an object have changed
+ * - called with reads/writes excluded by FS-Cache
+ */
+static int cachefiles_attr_changed(struct fscache_object *_object)
+{
+        struct cachefiles_object *object;
+        struct cachefiles_cache *cache;
+        const struct cred *saved_cred;
+        struct iattr newattrs;
+        uint64_t ni_size;
+        loff_t oi_size;
+        int ret;
+
+        _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size);
+
+        _enter("{OBJ%x},[%llu]",
+               _object->debug_id, (unsigned long long) ni_size);
+
+        object = container_of(_object, struct cachefiles_object, fscache);
+        cache = container_of(object->fscache.cache,
+                             struct cachefiles_cache, cache);
+
+        if (ni_size == object->i_size)
+                return 0;
+
+        if (!object->backer)
+                return -ENOBUFS;
+
+        ASSERT(S_ISREG(object->backer->d_inode->i_mode));
+
+        fscache_set_store_limit(&object->fscache, ni_size);
+
+        oi_size = i_size_read(object->backer->d_inode);
+        if (oi_size == ni_size)
+                return 0;
+
+        newattrs.ia_size = ni_size;
+        newattrs.ia_valid = ATTR_SIZE;
+
+        cachefiles_begin_secure(cache, &saved_cred);
+        mutex_lock(&object->backer->d_inode->i_mutex);
+        ret = notify_change(object->backer, &newattrs);
+        mutex_unlock(&object->backer->d_inode->i_mutex);
+        cachefiles_end_secure(cache, saved_cred);
+
+        if (ret == -EIO) {
+                fscache_set_store_limit(&object->fscache, 0);
+                cachefiles_io_error_obj(object, "Size set failed");
+                ret = -ENOBUFS;
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * dissociate a cache from all the pages it was backing
+ */
+static void cachefiles_dissociate_pages(struct fscache_cache *cache)
+{
+        _enter("");
+}
+
+const struct fscache_cache_ops cachefiles_cache_ops = {
+        .name                   = "cachefiles",
+        .alloc_object           = cachefiles_alloc_object,
+        .lookup_object          = cachefiles_lookup_object,
+        .lookup_complete        = cachefiles_lookup_complete,
+        .grab_object            = cachefiles_grab_object,
+        .update_object          = cachefiles_update_object,
+        .drop_object            = cachefiles_drop_object,
+        .put_object             = cachefiles_put_object,
+        .sync_cache             = cachefiles_sync_cache,
+        .attr_changed           = cachefiles_attr_changed,
+        .read_or_alloc_page     = cachefiles_read_or_alloc_page,
+        .read_or_alloc_pages    = cachefiles_read_or_alloc_pages,
+        .allocate_page          = cachefiles_allocate_page,
+        .allocate_pages         = cachefiles_allocate_pages,
+        .write_page             = cachefiles_write_page,
+        .uncache_page           = cachefiles_uncache_page,
+        .dissociate_pages       = cachefiles_dissociate_pages,
+};