7 files changed, 79 insertions, 160 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 854a8f05a610..4c5edcc8b6e9 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1381,7 +1381,7 @@ static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, i
 
 static int do_open(struct inode *inode, struct file *filp)
 {
-        nfs_fscache_set_inode_cookie(inode, filp);
+        nfs_fscache_open_file(inode, filp);
         return 0;
 }
 
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index cd6e7efd4305..3ef01f0ba0bc 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -178,163 +178,79 @@ void nfs_fscache_release_super_cookie(struct super_block *sb)
 /*
  * Initialise the per-inode cache cookie pointer for an NFS inode.
  */
-void nfs_fscache_init_inode_cookie(struct inode *inode)
+void nfs_fscache_init_inode(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))
+        nfsi->fscache = NULL;
+        if (!S_ISREG(inode->i_mode))
                 return;
-
-        if ((NFS_SB(sb)->options & NFS_OPTION_FSCACHE)) {
-                nfsi->fscache = fscache_acquire_cookie(
-                        NFS_SB(sb)->fscache,
-                        &nfs_fscache_inode_object_def,
-                        nfsi, true);
-
-                dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
-                         sb, nfsi, nfsi->fscache);
-        }
+        nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
+                                               &nfs_fscache_inode_object_def,
+                                               nfsi, false);
 }
 
 /*
  * Release a per-inode cookie.
  */
-void nfs_fscache_release_inode_cookie(struct inode *inode)
+void nfs_fscache_clear_inode(struct inode *inode)
 {
         struct nfs_inode *nfsi = NFS_I(inode);
+        struct fscache_cookie *cookie = nfs_i_fscache(inode);
 
-        dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n",
-                 nfsi, nfsi->fscache);
+        dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
 
-        fscache_relinquish_cookie(nfsi->fscache, 0);
+        fscache_relinquish_cookie(cookie, false);
         nfsi->fscache = NULL;
 }
 
-/*
- * Retire a per-inode cookie, destroying the data attached to it.
- */
-void nfs_fscache_zap_inode_cookie(struct inode *inode)
+static bool nfs_fscache_can_enable(void *data)
 {
-        struct nfs_inode *nfsi = NFS_I(inode);
+        struct inode *inode = data;
 
-        dfprintk(FSCACHE, "NFS: zapping cookie (0x%p/0x%p)\n",
-                 nfsi, nfsi->fscache);
-
-        fscache_relinquish_cookie(nfsi->fscache, 1);
-        nfsi->fscache = NULL;
+        return !inode_is_open_for_write(inode);
 }
 
 /*
- * 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 uncache any pages attached to this inode that
-                 * fscache knows about before turning off the cache.
-                 */
-                fscache_uncache_all_inode_pages(NFS_I(inode)->fscache, inode);
-                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);
-        }
-}
-EXPORT_SYMBOL_GPL(nfs_fscache_set_inode_cookie);
-
-/*
- * Replace a per-inode cookie due to revalidation detecting a file having
- * changed on the server.
+ * Enable or disable caching for a file that is being opened as appropriate.
+ * The cookie is allocated when the inode is initialised, but is not enabled at
+ * that time.  Enablement is deferred to file-open time to avoid stat() and
+ * access() thrashing the cache.
+ *
+ * For now, with NFS, only regular files that are open read-only will be able
+ * to use the cache.
+ *
+ * We enable the cache for an inode if we open it read-only and it isn't
+ * currently open for writing.  We disable the cache if the inode is open
+ * write-only.
+ *
+ * The caller uses the file struct to pin i_writecount on the inode before
+ * calling us when a file is opened for writing, so we can make use of that.
+ *
+ * Note that this may be invoked multiple times in parallel by parallel
+ * nfs_open() functions.
  */
-void nfs_fscache_reset_inode_cookie(struct inode *inode)
+void nfs_fscache_open_file(struct inode *inode, struct file *filp)
 {
         struct nfs_inode *nfsi = NFS_I(inode);
-        struct nfs_server *nfss = NFS_SERVER(inode);
-        NFS_IFDEBUG(struct fscache_cookie *old = nfsi->fscache);
+        struct fscache_cookie *cookie = nfs_i_fscache(inode);
 
-        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, true);
+        if (!fscache_cookie_valid(cookie))
+                return;
 
-                dfprintk(FSCACHE,
-                         "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",
-                         nfss, nfsi, old, nfsi->fscache);
+        if (inode_is_open_for_write(inode)) {
+                dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
+                clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
+                fscache_disable_cookie(cookie, true);
+                fscache_uncache_all_inode_pages(cookie, inode);
+        } else {
+                dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
+                fscache_enable_cookie(cookie, nfs_fscache_can_enable, inode);
+                if (fscache_cookie_enabled(cookie))
+                        set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
         }
-        nfs_fscache_inode_unlock(inode);
 }
+EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
 
 /*
  * Release the caching state associated with a page, if the page isn't busy
@@ -344,12 +260,11 @@ void nfs_fscache_reset_inode_cookie(struct inode *inode)
 int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 {
         if (PageFsCache(page)) {
-                struct nfs_inode *nfsi = NFS_I(page->mapping->host);
-                struct fscache_cookie *cookie = nfsi->fscache;
+                struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
 
                 BUG_ON(!cookie);
                 dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
-                         cookie, page, nfsi);
+                         cookie, page, NFS_I(page->mapping->host));
 
                 if (!fscache_maybe_release_page(cookie, page, gfp))
                         return 0;
@@ -367,13 +282,12 @@ int nfs_fscache_release_page(struct page *page, gfp_t gfp)
  */
 void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 {
-        struct nfs_inode *nfsi = NFS_I(inode);
-        struct fscache_cookie *cookie = nfsi->fscache;
+        struct fscache_cookie *cookie = nfs_i_fscache(inode);
 
         BUG_ON(!cookie);
 
         dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
-                 cookie, page, nfsi);
+                 cookie, page, NFS_I(inode));
 
         fscache_wait_on_page_write(cookie, page);
 
@@ -417,9 +331,9 @@ int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 
         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);
+                 nfs_i_fscache(inode), page, page->index, page->flags, inode);
 
-        ret = fscache_read_or_alloc_page(NFS_I(inode)->fscache,
+        ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
                                          page,
                                          nfs_readpage_from_fscache_complete,
                                          ctx,
@@ -459,9 +373,9 @@ int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
         int ret;
 
         dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
-                 NFS_I(inode)->fscache, npages, inode);
+                 nfs_i_fscache(inode), npages, inode);
 
-        ret = fscache_read_or_alloc_pages(NFS_I(inode)->fscache,
+        ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
                                           mapping, pages, nr_pages,
                                           nfs_readpage_from_fscache_complete,
                                           ctx,
@@ -506,15 +420,15 @@ void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 
         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);
+                 nfs_i_fscache(inode), page, page->index, page->flags, sync);
 
-        ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
+        ret = fscache_write_page(nfs_i_fscache(inode), 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);
+                fscache_uncache_page(nfs_i_fscache(inode), page);
                 nfs_add_fscache_stats(inode,
                                       NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
                 nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 4ecb76652eba..d7fe3e799f2f 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -76,11 +76,9 @@ extern void nfs_fscache_release_client_cookie(struct nfs_client *);
 extern void nfs_fscache_get_super_cookie(struct super_block *, const char *, int);
 extern void nfs_fscache_release_super_cookie(struct super_block *);
 
-extern void nfs_fscache_init_inode_cookie(struct inode *);
-extern void nfs_fscache_release_inode_cookie(struct inode *);
-extern void nfs_fscache_zap_inode_cookie(struct inode *);
-extern void nfs_fscache_set_inode_cookie(struct inode *, struct file *);
-extern void nfs_fscache_reset_inode_cookie(struct inode *);
+extern void nfs_fscache_init_inode(struct inode *);
+extern void nfs_fscache_clear_inode(struct inode *);
+extern void nfs_fscache_open_file(struct inode *, struct file *);
 
 extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
 extern int nfs_fscache_release_page(struct page *, gfp_t);
@@ -187,12 +185,10 @@ static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
 
 static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
 
-static inline void nfs_fscache_init_inode_cookie(struct inode *inode) {}
-static inline void nfs_fscache_release_inode_cookie(struct inode *inode) {}
-static inline void nfs_fscache_zap_inode_cookie(struct inode *inode) {}
-static inline void nfs_fscache_set_inode_cookie(struct inode *inode,
-                                                struct file *filp) {}
-static inline void nfs_fscache_reset_inode_cookie(struct inode *inode) {}
+static inline void nfs_fscache_init_inode(struct inode *inode) {}
+static inline void nfs_fscache_clear_inode(struct inode *inode) {}
+static inline void nfs_fscache_open_file(struct inode *inode,
+                                         struct file *filp) {}
 
 static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 {
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index eda8879171c4..bb90bff0cb7a 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -122,7 +122,7 @@ void nfs_clear_inode(struct inode *inode)
         WARN_ON_ONCE(!list_empty(&NFS_I(inode)->open_files));
         nfs_zap_acl_cache(inode);
         nfs_access_zap_cache(inode);
-        nfs_fscache_release_inode_cookie(inode);
+        nfs_fscache_clear_inode(inode);
 }
 EXPORT_SYMBOL_GPL(nfs_clear_inode);
 
@@ -459,7 +459,7 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr, st
                 nfsi->attrtimeo_timestamp = now;
                 nfsi->access_cache = RB_ROOT;
 
-                nfs_fscache_init_inode_cookie(inode);
+                nfs_fscache_init_inode(inode);
 
                 unlock_new_inode(inode);
         } else
@@ -854,7 +854,7 @@ int nfs_open(struct inode *inode, struct file *filp)
                 return PTR_ERR(ctx);
         nfs_file_set_open_context(filp, ctx);
         put_nfs_open_context(ctx);
-        nfs_fscache_set_inode_cookie(inode, filp);
+        nfs_fscache_open_file(inode, filp);
         return 0;
 }
 
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index e5b804dd944c..5b8a618a0f7a 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -74,7 +74,7 @@ nfs4_file_open(struct inode *inode, struct file *filp)
 
         nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
         nfs_file_set_open_context(filp, ctx);
-        nfs_fscache_set_inode_cookie(inode, filp);
+        nfs_fscache_open_file(inode, filp);
         err = 0;
 
 out_put_ctx:
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3f40547ba191..955dff5da56a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2292,6 +2292,11 @@ static inline void allow_write_access(struct file *file)
         if (file)
                 atomic_inc(&file_inode(file)->i_writecount);
 }
+static inline bool inode_is_open_for_write(const struct inode *inode)
+{
+        return atomic_read(&inode->i_writecount) > 0;
+}
+
 #ifdef CONFIG_IMA
 static inline void i_readcount_dec(struct inode *inode)
 {
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 3ea4cde8701c..14a48207a304 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -269,9 +269,13 @@ static inline int NFS_STALE(const struct inode *inode)
         return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
 }
 
-static inline int NFS_FSCACHE(const struct inode *inode)
+static inline struct fscache_cookie *nfs_i_fscache(struct inode *inode)
 {
-        return test_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
+#ifdef CONFIG_NFS_FSCACHE
+        return NFS_I(inode)->fscache;
+#else
+        return NULL;
+#endif
 }
 
 static inline __u64 NFS_FILEID(const struct inode *inode)