NFS: Use local disk inode cache

Bind data storage objects in the local cache to NFS inodes.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

1 files changed, 162 insertions, 0 deletions

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index ab2de2c92b21..e3816eb53fb8 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -166,3 +166,165 @@ void nfs_fscache_release_super_cookie(struct super_block *sb)
                 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);
+}