1 files changed, 523 insertions, 0 deletions

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
new file mode 100644
index 000000000000..379be678cb7e
--- /dev/null
+++ b/fs/nfs/fscache.c
@@ -0,0 +1,523 @@
+/* NFS filesystem cache interface
+ *
+ * Copyright (C) 2008 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/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_fs_sb.h>
+#include <linux/in6.h>
+#include <linux/seq_file.h>
+
+#include "internal.h"
+#include "iostat.h"
+#include "fscache.h"
+
+#define NFSDBG_FACILITY         NFSDBG_FSCACHE
+
+static struct rb_root nfs_fscache_keys = RB_ROOT;
+static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
+
+/*
+ * Get the per-client index cookie for an NFS client if the appropriate mount
+ * flag was set
+ * - We always try and get an index cookie for the client, but get filehandle
+ *   cookies on a per-superblock basis, depending on the mount flags
+ */
+void nfs_fscache_get_client_cookie(struct nfs_client *clp)
+{
+        /* create a cache index for looking up filehandles */
+        clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
+                                              &nfs_fscache_server_index_def,
+                                              clp);
+        dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
+                 clp, clp->fscache);
+}
+
+/*
+ * Dispose of a per-client cookie
+ */
+void nfs_fscache_release_client_cookie(struct nfs_client *clp)
+{
+        dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
+                 clp, clp->fscache);
+
+        fscache_relinquish_cookie(clp->fscache, 0);
+        clp->fscache = NULL;
+}
+
+/*
+ * Get the cache cookie for an NFS superblock.  We have to handle
+ * uniquification here because the cache doesn't do it for us.
+ */
+void nfs_fscache_get_super_cookie(struct super_block *sb,
+                                  struct nfs_parsed_mount_data *data)
+{
+        struct nfs_fscache_key *key, *xkey;
+        struct nfs_server *nfss = NFS_SB(sb);
+        struct rb_node **p, *parent;
+        const char *uniq = data->fscache_uniq ?: "";
+        int diff, ulen;
+
+        ulen = strlen(uniq);
+        key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
+        if (!key)
+                return;
+
+        key->nfs_client = nfss->nfs_client;
+        key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
+        key->key.nfs_server.flags = nfss->flags;
+        key->key.nfs_server.rsize = nfss->rsize;
+        key->key.nfs_server.wsize = nfss->wsize;
+        key->key.nfs_server.acregmin = nfss->acregmin;
+        key->key.nfs_server.acregmax = nfss->acregmax;
+        key->key.nfs_server.acdirmin = nfss->acdirmin;
+        key->key.nfs_server.acdirmax = nfss->acdirmax;
+        key->key.nfs_server.fsid = nfss->fsid;
+        key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
+
+        key->key.uniq_len = ulen;
+        memcpy(key->key.uniquifier, uniq, ulen);
+
+        spin_lock(&nfs_fscache_keys_lock);
+        p = &nfs_fscache_keys.rb_node;
+        parent = NULL;
+        while (*p) {
+                parent = *p;
+                xkey = rb_entry(parent, struct nfs_fscache_key, node);
+
+                if (key->nfs_client < xkey->nfs_client)
+                        goto go_left;
+                if (key->nfs_client > xkey->nfs_client)
+                        goto go_right;
+
+                diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
+                if (diff < 0)
+                        goto go_left;
+                if (diff > 0)
+                        goto go_right;
+
+                if (key->key.uniq_len == 0)
+                        goto non_unique;
+                diff = memcmp(key->key.uniquifier,
+                              xkey->key.uniquifier,
+                              key->key.uniq_len);
+                if (diff < 0)
+                        goto go_left;
+                if (diff > 0)
+                        goto go_right;
+                goto non_unique;
+
+        go_left:
+                p = &(*p)->rb_left;
+                continue;
+        go_right:
+                p = &(*p)->rb_right;
+        }
+
+        rb_link_node(&key->node, parent, p);
+        rb_insert_color(&key->node, &nfs_fscache_keys);
+        spin_unlock(&nfs_fscache_keys_lock);
+        nfss->fscache_key = key;
+
+        /* create a cache index for looking up filehandles */
+        nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
+                                               &nfs_fscache_super_index_def,
+                                               nfss);
+        dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
+                 nfss, nfss->fscache);
+        return;
+
+non_unique:
+        spin_unlock(&nfs_fscache_keys_lock);
+        kfree(key);
+        nfss->fscache_key = NULL;
+        nfss->fscache = NULL;
+        printk(KERN_WARNING "NFS:"
+               " Cache request denied due to non-unique superblock keys\n");
+}
+
+/*
+ * release a per-superblock cookie
+ */
+void nfs_fscache_release_super_cookie(struct super_block *sb)
+{
+        struct nfs_server *nfss = NFS_SB(sb);
+
+        dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
+                 nfss, nfss->fscache);
+
+        fscache_relinquish_cookie(nfss->fscache, 0);
+        nfss->fscache = NULL;
+
+        if (nfss->fscache_key) {
+                spin_lock(&nfs_fscache_keys_lock);
+                rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
+                spin_unlock(&nfs_fscache_keys_lock);
+                kfree(nfss->fscache_key);
+                nfss->fscache_key = NULL;
+        }
+}
+
+/*
+ * Initialise the per-inode cache cookie pointer for an NFS inode.
+ */
+void nfs_fscache_init_inode_cookie(struct inode *inode)
+{
+        NFS_I(inode)->fscache = NULL;
+        if (S_ISREG(inode->i_mode))
+                set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
+}
+
+/*
+ * Get the per-inode cache cookie for an NFS inode.
+ */
+static void nfs_fscache_enable_inode_cookie(struct inode *inode)
+{
+        struct super_block *sb = inode->i_sb;
+        struct nfs_inode *nfsi = NFS_I(inode);
+
+        if (nfsi->fscache || !NFS_FSCACHE(inode))
+                return;
+
+        if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
+                nfsi->fscache = fscache_acquire_cookie(
+                        NFS_SB(sb)->fscache,
+                        &nfs_fscache_inode_object_def,
+                        nfsi);
+
+                dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
+                         sb, nfsi, nfsi->fscache);
+        }
+}
+
+/*
+ * Release a per-inode cookie.
+ */
+void nfs_fscache_release_inode_cookie(struct inode *inode)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+
+        dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
+                 nfsi, nfsi->fscache);
+
+        fscache_relinquish_cookie(nfsi->fscache, 0);
+        nfsi->fscache = NULL;
+}
+
+/*
+ * Retire a per-inode cookie, destroying the data attached to it.
+ */
+void nfs_fscache_zap_inode_cookie(struct inode *inode)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+
+        dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
+                 nfsi, nfsi->fscache);
+
+        fscache_relinquish_cookie(nfsi->fscache, 1);
+        nfsi->fscache = NULL;
+}
+
+/*
+ * Turn off the cache with regard to a per-inode cookie if opened for writing,
+ * invalidating all the pages in the page cache relating to the associated
+ * inode to clear the per-page caching.
+ */
+static void nfs_fscache_disable_inode_cookie(struct inode *inode)
+{
+        clear_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
+
+        if (NFS_I(inode)->fscache) {
+                dfprintk(FSCACHE,
+                         "NFS: nfsi 0x%p turning cache off\n", NFS_I(inode));
+
+                /* Need to invalidate any mapped pages that were read in before
+                 * turning off the cache.
+                 */
+                if (inode->i_mapping && inode->i_mapping->nrpages)
+                        invalidate_inode_pages2(inode->i_mapping);
+
+                nfs_fscache_zap_inode_cookie(inode);
+        }
+}
+
+/*
+ * wait_on_bit() sleep function for uninterruptible waiting
+ */
+static int nfs_fscache_wait_bit(void *flags)
+{
+        schedule();
+        return 0;
+}
+
+/*
+ * Lock against someone else trying to also acquire or relinquish a cookie
+ */
+static inline void nfs_fscache_inode_lock(struct inode *inode)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+
+        while (test_and_set_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags))
+                wait_on_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK,
+                            nfs_fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+}
+
+/*
+ * Unlock cookie management lock
+ */
+static inline void nfs_fscache_inode_unlock(struct inode *inode)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+
+        smp_mb__before_clear_bit();
+        clear_bit(NFS_INO_FSCACHE_LOCK, &nfsi->flags);
+        smp_mb__after_clear_bit();
+        wake_up_bit(&nfsi->flags, NFS_INO_FSCACHE_LOCK);
+}
+
+/*
+ * Decide if we should enable or disable local caching for this inode.
+ * - For now, with NFS, only regular files that are open read-only will be able
+ *   to use the cache.
+ * - May be invoked multiple times in parallel by parallel nfs_open() functions.
+ */
+void nfs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
+{
+        if (NFS_FSCACHE(inode)) {
+                nfs_fscache_inode_lock(inode);
+                if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
+                        nfs_fscache_disable_inode_cookie(inode);
+                else
+                        nfs_fscache_enable_inode_cookie(inode);
+                nfs_fscache_inode_unlock(inode);
+        }
+}
+
+/*
+ * Replace a per-inode cookie due to revalidation detecting a file having
+ * changed on the server.
+ */
+void nfs_fscache_reset_inode_cookie(struct inode *inode)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+        struct nfs_server *nfss = NFS_SERVER(inode);
+        struct fscache_cookie *old = nfsi->fscache;
+
+        nfs_fscache_inode_lock(inode);
+        if (nfsi->fscache) {
+                /* retire the current fscache cache and get a new one */
+                fscache_relinquish_cookie(nfsi->fscache, 1);
+
+                nfsi->fscache = fscache_acquire_cookie(
+                        nfss->nfs_client->fscache,
+                        &nfs_fscache_inode_object_def,
+                        nfsi);
+
+                dfprintk(FSCACHE,
+                         "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
+                         nfss, nfsi, old, nfsi->fscache);
+        }
+        nfs_fscache_inode_unlock(inode);
+}
+
+/*
+ * Release the caching state associated with a page, if the page isn't busy
+ * interacting with the cache.
+ * - Returns true (can release page) or false (page busy).
+ */
+int nfs_fscache_release_page(struct page *page, gfp_t gfp)
+{
+        struct nfs_inode *nfsi = NFS_I(page->mapping->host);
+        struct fscache_cookie *cookie = nfsi->fscache;
+
+        BUG_ON(!cookie);
+
+        if (fscache_check_page_write(cookie, page)) {
+                if (!(gfp & __GFP_WAIT))
+                        return 0;
+                fscache_wait_on_page_write(cookie, page);
+        }
+
+        if (PageFsCache(page)) {
+                dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
+                         cookie, page, nfsi);
+
+                fscache_uncache_page(cookie, page);
+                nfs_add_fscache_stats(page->mapping->host,
+                                      NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
+        }
+
+        return 1;
+}
+
+/*
+ * Release the caching state associated with a page if undergoing complete page
+ * invalidation.
+ */
+void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+        struct fscache_cookie *cookie = nfsi->fscache;
+
+        BUG_ON(!cookie);
+
+        dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
+                 cookie, page, nfsi);
+
+        fscache_wait_on_page_write(cookie, page);
+
+        BUG_ON(!PageLocked(page));
+        fscache_uncache_page(cookie, page);
+        nfs_add_fscache_stats(page->mapping->host,
+                              NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
+}
+
+/*
+ * Handle completion of a page being read from the cache.
+ * - Called in process (keventd) context.
+ */
+static void nfs_readpage_from_fscache_complete(struct page *page,
+                                               void *context,
+                                               int error)
+{
+        dfprintk(FSCACHE,
+                 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
+                 page, context, error);
+
+        /* if the read completes with an error, we just unlock the page and let
+         * the VM reissue the readpage */
+        if (!error) {
+                SetPageUptodate(page);
+                unlock_page(page);
+        } else {
+                error = nfs_readpage_async(context, page->mapping->host, page);
+                if (error)
+                        unlock_page(page);
+        }
+}
+
+/*
+ * Retrieve a page from fscache
+ */
+int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
+                                struct inode *inode, struct page *page)
+{
+        int ret;
+
+        dfprintk(FSCACHE,
+                 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
+                 NFS_I(inode)->fscache, page, page->index, page->flags, inode);
+
+        ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
+                                         page,
+                                         nfs_readpage_from_fscache_complete,
+                                         ctx,
+                                         GFP_KERNEL);
+
+        switch (ret) {
+        case 0: /* read BIO submitted (page in fscache) */
+                dfprintk(FSCACHE,
+                         "NFS:    readpage_from_fscache: BIO submitted\n");
+                nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK, 1);
+                return ret;
+
+        case -ENOBUFS: /* inode not in cache */
+        case -ENODATA: /* page not in cache */
+                nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
+                dfprintk(FSCACHE,
+                         "NFS:    readpage_from_fscache %d\n", ret);
+                return 1;
+
+        default:
+                dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
+                nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL, 1);
+        }
+        return ret;
+}
+
+/*
+ * Retrieve a set of pages from fscache
+ */
+int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
+                                 struct inode *inode,
+                                 struct address_space *mapping,
+                                 struct list_head *pages,
+                                 unsigned *nr_pages)
+{
+        int ret, npages = *nr_pages;
+
+        dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
+                 NFS_I(inode)->fscache, npages, inode);
+
+        ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
+                                          mapping, pages, nr_pages,
+                                          nfs_readpage_from_fscache_complete,
+                                          ctx,
+                                          mapping_gfp_mask(mapping));
+        if (*nr_pages < npages)
+                nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
+                                      npages);
+        if (*nr_pages > 0)
+                nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
+                                      *nr_pages);
+
+        switch (ret) {
+        case 0: /* read submitted to the cache for all pages */
+                BUG_ON(!list_empty(pages));
+                BUG_ON(*nr_pages != 0);
+                dfprintk(FSCACHE,
+                         "NFS: nfs_getpages_from_fscache: submitted\n");
+
+                return ret;
+
+        case -ENOBUFS: /* some pages aren't cached and can't be */
+        case -ENODATA: /* some pages aren't cached */
+                dfprintk(FSCACHE,
+                         "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
+                return 1;
+
+        default:
+                dfprintk(FSCACHE,
+                         "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
+        }
+
+        return ret;
+}
+
+/*
+ * Store a newly fetched page in fscache
+ * - PG_fscache must be set on the page
+ */
+void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
+{
+        int ret;
+
+        dfprintk(FSCACHE,
+                 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
+                 NFS_I(inode)->fscache, page, page->index, page->flags, sync);
+
+        ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
+        dfprintk(FSCACHE,
+                 "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
+                 page, page->index, page->flags, ret);
+
+        if (ret != 0) {
+                fscache_uncache_page(NFS_I(inode)->fscache, page);
+                nfs_add_fscache_stats(inode,
+                                      NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
+                nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
+        } else {
+                nfs_add_fscache_stats(inode,
+                                      NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
+        }
+}