FS-Cache: Provide the ability to enable/disable cookies

Provide the ability to enable and disable fscache cookies.  A disabled cookie
will reject or ignore further requests to:

	Acquire a child cookie
	Invalidate and update backing objects
	Check the consistency of a backing object
	Allocate storage for backing page
	Read backing pages
	Write to backing pages

but still allows:

	Checks/waits on the completion of already in-progress objects
	Uncaching of pages
	Relinquishment of cookies

Two new operations are provided:

 (1) Disable a cookie:

	void fscache_disable_cookie(struct fscache_cookie *cookie,
				    bool invalidate);

     If the cookie is not already disabled, this locks the cookie against other
     dis/enablement ops, marks the cookie as being disabled, discards or
     invalidates any backing objects and waits for cessation of activity on any
     associated object.

     This is a wrapper around a chunk split out of fscache_relinquish_cookie(),
     but it reinitialises the cookie such that it can be reenabled.

     All possible failures are handled internally.  The caller should consider
     calling fscache_uncache_all_inode_pages() afterwards to make sure all page
     markings are cleared up.

 (2) Enable a cookie:

	void fscache_enable_cookie(struct fscache_cookie *cookie,
				   bool (*can_enable)(void *data),
				   void *data)

     If the cookie is not already enabled, this locks the cookie against other
     dis/enablement ops, invokes can_enable() and, if the cookie is not an
     index cookie, will begin the procedure of acquiring backing objects.

     The optional can_enable() function is passed the data argument and returns
     a ruling as to whether or not enablement should actually be permitted to
     begin.

     All possible failures are handled internally.  The cookie will only be
     marked as enabled if provisional backing objects are allocated.

A later patch will introduce these to NFS.  Cookie enablement during nfs_open()
is then contingent on i_writecount <= 0.  can_enable() checks for a race
between open(O_RDONLY) and open(O_WRONLY/O_RDWR).  This simplifies NFS's cookie
handling and allows us to get rid of open(O_RDONLY) accidentally introducing
caching to an inode that's open for writing already.

One operation has its API modified:

 (3) Acquire a cookie.

	struct fscache_cookie *fscache_acquire_cookie(
		struct fscache_cookie *parent,
		const struct fscache_cookie_def *def,
		void *netfs_data,
		bool enable);

     This now has an additional argument that indicates whether the requested
     cookie should be enabled by default.  It doesn't need the can_enable()
     function because the caller must prevent multiple calls for the same netfs
     object and it doesn't need to take the enablement lock because no one else
     can get at the cookie before this returns.

Signed-off-by: David Howells <dhowells@redhat.com

14 files changed, 174 insertions, 75 deletions

diff --git a/fs/9p/cache.c b/fs/9p/cache.c
index a9ea73d6dcf3..2b7a032c37bc 100644
--- a/fs/9p/cache.c
+++ b/fs/9p/cache.c
@@ -90,7 +90,7 @@ void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 
         v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
                                                 &v9fs_cache_session_index_def,
-                                                v9ses);
+                                                v9ses, true);
         p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
                  v9ses, v9ses->fscache);
 }
@@ -204,7 +204,7 @@ void v9fs_cache_inode_get_cookie(struct inode *inode)
         v9ses = v9fs_inode2v9ses(inode);
         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
                                                   &v9fs_cache_inode_index_def,
-                                                  v9inode);
+                                                  v9inode, true);
 
         p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
                  inode, v9inode->fscache);
@@ -271,7 +271,7 @@ void v9fs_cache_inode_reset_cookie(struct inode *inode)
         v9ses = v9fs_inode2v9ses(inode);
         v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
                                                   &v9fs_cache_inode_index_def,
-                                                  v9inode);
+                                                  v9inode, true);
         p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
                  inode, old, v9inode->fscache);
 
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 3c090b7555ea..ca0a3cf93791 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -179,7 +179,7 @@ struct afs_cell *afs_cell_create(const char *name, unsigned namesz,
         /* put it up for caching (this never returns an error) */
         cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
                                              &afs_cell_cache_index_def,
-                                             cell);
+                                             cell, true);
 #endif
 
         /* add to the cell lists */
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 789bc253b5f6..ce25d755b7aa 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -259,7 +259,7 @@ struct inode *afs_iget(struct super_block *sb, struct key *key,
 #ifdef CONFIG_AFS_FSCACHE
         vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
                                               &afs_vnode_cache_index_def,
-                                              vnode);
+                                              vnode, true);
 #endif
 
         ret = afs_inode_map_status(vnode, key);
diff --git a/fs/afs/vlocation.c b/fs/afs/vlocation.c
index 57bcb1596530..b6df2e83809f 100644
--- a/fs/afs/vlocation.c
+++ b/fs/afs/vlocation.c
@@ -308,7 +308,8 @@ static int afs_vlocation_fill_in_record(struct afs_vlocation *vl,
         /* see if we have an in-cache copy (will set vl->valid if there is) */
 #ifdef CONFIG_AFS_FSCACHE
         vl->cache = fscache_acquire_cookie(vl->cell->cache,
-                                           &afs_vlocation_cache_index_def, vl);
+                                           &afs_vlocation_cache_index_def, vl,
+                                           true);
 #endif
 
         if (vl->valid) {
diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index 401eeb21869f..2b607257820c 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -131,7 +131,7 @@ struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
 #ifdef CONFIG_AFS_FSCACHE
         volume->cache = fscache_acquire_cookie(vlocation->cache,
                                                &afs_volume_cache_index_def,
-                                               volume);
+                                               volume, true);
 #endif
         afs_get_vlocation(vlocation);
         volume->vlocation = vlocation;
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 43eb5592cdea..00baf1419989 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -270,7 +270,7 @@ static void cachefiles_drop_object(struct fscache_object *_object)
 #endif
 
         /* delete retired objects */
-        if (test_bit(FSCACHE_COOKIE_RETIRED, &object->fscache.cookie->flags) &&
+        if (test_bit(FSCACHE_OBJECT_RETIRED, &object->fscache.flags) &&
             _object != cache->cache.fsdef
             ) {
                 _debug("- retire object OBJ%x", object->fscache.debug_id);
diff --git a/fs/ceph/cache.c b/fs/ceph/cache.c
index 6bfe65e0b038..7db2e6ca4b8f 100644
--- a/fs/ceph/cache.c
+++ b/fs/ceph/cache.c
@@ -68,7 +68,7 @@ int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
 {
         fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
                                               &ceph_fscache_fsid_object_def,
-                                              fsc);
+                                              fsc, true);
 
         if (fsc->fscache == NULL) {
                 pr_err("Unable to resgister fsid: %p fscache cookie", fsc);
@@ -204,7 +204,7 @@ void ceph_fscache_register_inode_cookie(struct ceph_fs_client* fsc,
 
         ci->fscache = fscache_acquire_cookie(fsc->fscache,
                                              &ceph_fscache_inode_object_def,
-                                             ci);
+                                             ci, true);
 done:
         mutex_unlock(&inode->i_mutex);
 
diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index 2f4bc5a58054..fe2492d2a8fc 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -27,7 +27,7 @@ void cifs_fscache_get_client_cookie(struct TCP_Server_Info *server)
 {
         server->fscache =
                 fscache_acquire_cookie(cifs_fscache_netfs.primary_index,
-                                &cifs_fscache_server_index_def, server);
+                                &cifs_fscache_server_index_def, server, true);
         cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
                  __func__, server, server->fscache);
 }
@@ -46,7 +46,7 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 
         tcon->fscache =
                 fscache_acquire_cookie(server->fscache,
-                                &cifs_fscache_super_index_def, tcon);
+                                &cifs_fscache_super_index_def, tcon, true);
         cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
                  __func__, server->fscache, tcon->fscache);
 }
@@ -69,7 +69,7 @@ static void cifs_fscache_enable_inode_cookie(struct inode *inode)
 
         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_FSCACHE) {
                 cifsi->fscache = fscache_acquire_cookie(tcon->fscache,
-                                &cifs_fscache_inode_object_def, cifsi);
+                                &cifs_fscache_inode_object_def, cifsi, true);
                 cifs_dbg(FYI, "%s: got FH cookie (0x%p/0x%p)\n",
                          __func__, tcon->fscache, cifsi->fscache);
         }
@@ -119,7 +119,7 @@ void cifs_fscache_reset_inode_cookie(struct inode *inode)
                 cifsi->fscache = fscache_acquire_cookie(
                                         cifs_sb_master_tcon(cifs_sb)->fscache,
                                         &cifs_fscache_inode_object_def,
-                                        cifsi);
+                                        cifsi, true);
                 cifs_dbg(FYI, "%s: new cookie 0x%p oldcookie 0x%p\n",
                          __func__, cifsi->fscache, old);
         }
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index d851aa555d28..29d7feb62cf7 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -58,15 +58,16 @@ void fscache_cookie_init_once(void *_cookie)
 struct fscache_cookie *__fscache_acquire_cookie(
         struct fscache_cookie *parent,
         const struct fscache_cookie_def *def,
-        void *netfs_data)
+        void *netfs_data,
+        bool enable)
 {
         struct fscache_cookie *cookie;
 
         BUG_ON(!def);
 
-        _enter("{%s},{%s},%p",
+        _enter("{%s},{%s},%p,%u",
                parent ? (char *) parent->def->name : "<no-parent>",
-               def->name, netfs_data);
+               def->name, netfs_data, enable);
 
         fscache_stat(&fscache_n_acquires);
 
@@ -106,7 +107,7 @@ struct fscache_cookie *__fscache_acquire_cookie(
         cookie->def             = def;
         cookie->parent          = parent;
         cookie->netfs_data      = netfs_data;
-        cookie->flags           = 0;
+        cookie->flags           = (1 << FSCACHE_COOKIE_NO_DATA_YET);
 
         /* radix tree insertion won't use the preallocation pool unless it's
          * told it may not wait */
@@ -124,16 +125,22 @@ struct fscache_cookie *__fscache_acquire_cookie(
                 break;
         }
 
-        /* if the object is an index then we need do nothing more here - we
-         * create indices on disk when we need them as an index may exist in
-         * multiple caches */
-        if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
-                if (fscache_acquire_non_index_cookie(cookie) < 0) {
-                        atomic_dec(&parent->n_children);
-                        __fscache_cookie_put(cookie);
-                        fscache_stat(&fscache_n_acquires_nobufs);
-                        _leave(" = NULL");
-                        return NULL;
+        if (enable) {
+                /* if the object is an index then we need do nothing more here
+                 * - we create indices on disk when we need them as an index
+                 * may exist in multiple caches */
+                if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+                        if (fscache_acquire_non_index_cookie(cookie) == 0) {
+                                set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+                        } else {
+                                atomic_dec(&parent->n_children);
+                                __fscache_cookie_put(cookie);
+                                fscache_stat(&fscache_n_acquires_nobufs);
+                                _leave(" = NULL");
+                                return NULL;
+                        }
+                } else {
+                        set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
                 }
         }
 
@@ -144,6 +151,39 @@ struct fscache_cookie *__fscache_acquire_cookie(
 EXPORT_SYMBOL(__fscache_acquire_cookie);
 
 /*
+ * Enable a cookie to permit it to accept new operations.
+ */
+void __fscache_enable_cookie(struct fscache_cookie *cookie,
+                             bool (*can_enable)(void *data),
+                             void *data)
+{
+        _enter("%p", cookie);
+
+        wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
+                         fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+
+        if (test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
+                goto out_unlock;
+
+        if (can_enable && !can_enable(data)) {
+                /* The netfs decided it didn't want to enable after all */
+        } else if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+                /* Wait for outstanding disablement to complete */
+                __fscache_wait_on_invalidate(cookie);
+
+                if (fscache_acquire_non_index_cookie(cookie) == 0)
+                        set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+        } else {
+                set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
+        }
+
+out_unlock:
+        clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
+        wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
+}
+EXPORT_SYMBOL(__fscache_enable_cookie);
+
+/*
  * acquire a non-index cookie
  * - this must make sure the index chain is instantiated and instantiate the
  *   object representation too
@@ -157,7 +197,7 @@ static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
 
         _enter("");
 
-        cookie->flags = 1 << FSCACHE_COOKIE_UNAVAILABLE;
+        set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
 
         /* now we need to see whether the backing objects for this cookie yet
          * exist, if not there'll be nothing to search */
@@ -180,9 +220,7 @@ static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
 
         _debug("cache %s", cache->tag->name);
 
-        cookie->flags =
-                (1 << FSCACHE_COOKIE_LOOKING_UP) |
-                (1 << FSCACHE_COOKIE_NO_DATA_YET);
+        set_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
 
         /* ask the cache to allocate objects for this cookie and its parent
          * chain */
@@ -398,7 +436,8 @@ void __fscache_invalidate(struct fscache_cookie *cookie)
         if (!hlist_empty(&cookie->backing_objects)) {
                 spin_lock(&cookie->lock);
 
-                if (!hlist_empty(&cookie->backing_objects) &&
+                if (fscache_cookie_enabled(cookie) &&
+                    !hlist_empty(&cookie->backing_objects) &&
                     !test_and_set_bit(FSCACHE_COOKIE_INVALIDATING,
                                       &cookie->flags)) {
                         object = hlist_entry(cookie->backing_objects.first,
@@ -452,10 +491,14 @@ void __fscache_update_cookie(struct fscache_cookie *cookie)
 
         spin_lock(&cookie->lock);
 
-        /* update the index entry on disk in each cache backing this cookie */
-        hlist_for_each_entry(object,
-                             &cookie->backing_objects, cookie_link) {
-                fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
+        if (fscache_cookie_enabled(cookie)) {
+                /* update the index entry on disk in each cache backing this
+                 * cookie.
+                 */
+                hlist_for_each_entry(object,
+                                     &cookie->backing_objects, cookie_link) {
+                        fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
+                }
         }
 
         spin_unlock(&cookie->lock);
@@ -464,28 +507,14 @@ void __fscache_update_cookie(struct fscache_cookie *cookie)
 EXPORT_SYMBOL(__fscache_update_cookie);
 
 /*
- * release a cookie back to the cache
- * - the object will be marked as recyclable on disk if retire is true
- * - all dependents of this cookie must have already been unregistered
- *   (indices/files/pages)
+ * Disable a cookie to stop it from accepting new requests from the netfs.
  */
-void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
+void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
 {
         struct fscache_object *object;
+        bool awaken = false;
 
-        fscache_stat(&fscache_n_relinquishes);
-        if (retire)
-                fscache_stat(&fscache_n_relinquishes_retire);
-
-        if (!cookie) {
-                fscache_stat(&fscache_n_relinquishes_null);
-                _leave(" [no cookie]");
-                return;
-        }
-
-        _enter("%p{%s,%p,%d},%d",
-               cookie, cookie->def->name, cookie->netfs_data,
-               atomic_read(&cookie->n_active), retire);
+        _enter("%p,%u", cookie, invalidate);
 
         ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
 
@@ -495,24 +524,82 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
                 BUG();
         }
 
-        /* No further netfs-accessing operations on this cookie permitted */
-        set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags);
-        if (retire)
-                set_bit(FSCACHE_COOKIE_RETIRED, &cookie->flags);
+        wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
+                         fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+        if (!test_and_clear_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
+                goto out_unlock_enable;
+
+        /* If the cookie is being invalidated, wait for that to complete first
+         * so that we can reuse the flag.
+         */
+        __fscache_wait_on_invalidate(cookie);
+
+        /* Dispose of the backing objects */
+        set_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags);
 
         spin_lock(&cookie->lock);
-        hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
-                fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
+        if (!hlist_empty(&cookie->backing_objects)) {
+                hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
+                        if (invalidate)
+                                set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
+                        fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
+                }
+        } else {
+                if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
+                        awaken = true;
         }
         spin_unlock(&cookie->lock);
+        if (awaken)
+                wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
 
         /* Wait for cessation of activity requiring access to the netfs (when
-         * n_active reaches 0).
+         * n_active reaches 0).  This makes sure outstanding reads and writes
+         * have completed.
          */
         if (!atomic_dec_and_test(&cookie->n_active))
                 wait_on_atomic_t(&cookie->n_active, fscache_wait_atomic_t,
                                  TASK_UNINTERRUPTIBLE);
 
+        /* Reset the cookie state if it wasn't relinquished */
+        if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags)) {
+                atomic_inc(&cookie->n_active);
+                set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
+        }
+
+out_unlock_enable:
+        clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
+        wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
+        _leave("");
+}
+EXPORT_SYMBOL(__fscache_disable_cookie);
+
+/*
+ * release a cookie back to the cache
+ * - the object will be marked as recyclable on disk if retire is true
+ * - all dependents of this cookie must have already been unregistered
+ *   (indices/files/pages)
+ */
+void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
+{
+        fscache_stat(&fscache_n_relinquishes);
+        if (retire)
+                fscache_stat(&fscache_n_relinquishes_retire);
+
+        if (!cookie) {
+                fscache_stat(&fscache_n_relinquishes_null);
+                _leave(" [no cookie]");
+                return;
+        }
+
+        _enter("%p{%s,%p,%d},%d",
+               cookie, cookie->def->name, cookie->netfs_data,
+               atomic_read(&cookie->n_active), retire);
+
+        /* No further netfs-accessing operations on this cookie permitted */
+        set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags);
+
+        __fscache_disable_cookie(cookie, retire);
+
         /* Clear pointers back to the netfs */
         cookie->netfs_data      = NULL;
         cookie->def             = NULL;
@@ -592,7 +679,8 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
 
         spin_lock(&cookie->lock);
 
-        if (hlist_empty(&cookie->backing_objects))
+        if (!fscache_cookie_enabled(cookie) ||
+            hlist_empty(&cookie->backing_objects))
                 goto inconsistent;
         object = hlist_entry(cookie->backing_objects.first,
                              struct fscache_object, cookie_link);
diff --git a/fs/fscache/fsdef.c b/fs/fscache/fsdef.c
index 10a2ade0bdf8..5a117df2a9ef 100644
--- a/fs/fscache/fsdef.c
+++ b/fs/fscache/fsdef.c
@@ -59,6 +59,7 @@ struct fscache_cookie fscache_fsdef_index = {
         .lock           = __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
         .backing_objects = HLIST_HEAD_INIT,
         .def            = &fscache_fsdef_index_def,
+        .flags          = 1 << FSCACHE_COOKIE_ENABLED,
 };
 EXPORT_SYMBOL(fscache_fsdef_index);
 
diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
index b1bb6117473a..989f39401547 100644
--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -45,6 +45,7 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
         netfs->primary_index->def               = &fscache_fsdef_netfs_def;
         netfs->primary_index->parent            = &fscache_fsdef_index;
         netfs->primary_index->netfs_data        = netfs;
+        netfs->primary_index->flags             = 1 << FSCACHE_COOKIE_ENABLED;
 
         atomic_inc(&netfs->primary_index->parent->usage);
         atomic_inc(&netfs->primary_index->parent->n_children);
diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index 86d75a60b20c..dcb821617774 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -495,6 +495,7 @@ void fscache_object_lookup_negative(struct fscache_object *object)
                  * returning ENODATA.
                  */
                 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
+                clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
 
                 _debug("wake up lookup %p", &cookie->flags);
                 clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
@@ -527,6 +528,7 @@ void fscache_obtained_object(struct fscache_object *object)
 
                 /* We do (presumably) have data */
                 clear_bit_unlock(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
+                clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
 
                 /* Allow write requests to begin stacking up and read requests
                  * to begin shovelling data.
@@ -679,7 +681,8 @@ static const struct fscache_state *fscache_drop_object(struct fscache_object *ob
          */
         spin_lock(&cookie->lock);
         hlist_del_init(&object->cookie_link);
-        if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
+        if (hlist_empty(&cookie->backing_objects) &&
+            test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
                 awaken = true;
         spin_unlock(&cookie->lock);
 
@@ -927,7 +930,7 @@ static const struct fscache_state *_fscache_invalidate_object(struct fscache_obj
          */
         if (!fscache_use_cookie(object)) {
                 ASSERT(object->cookie->stores.rnode == NULL);
-                set_bit(FSCACHE_COOKIE_RETIRED, &cookie->flags);
+                set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
                 _leave(" [no cookie]");
                 return transit_to(KILL_OBJECT);
         }
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 0fe42a6d0e9c..7f5c658af755 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -204,7 +204,8 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
 
         spin_lock(&cookie->lock);
 
-        if (hlist_empty(&cookie->backing_objects))
+        if (!fscache_cookie_enabled(cookie) ||
+            hlist_empty(&cookie->backing_objects))
                 goto nobufs;
         object = hlist_entry(cookie->backing_objects.first,
                              struct fscache_object, cookie_link);
@@ -410,7 +411,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
                 return -ERESTARTSYS;
 
         op = fscache_alloc_retrieval(cookie, page->mapping,
-                                     end_io_func,context);
+                                     end_io_func, context);
         if (!op) {
                 _leave(" = -ENOMEM");
                 return -ENOMEM;
@@ -419,7 +420,8 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
 
         spin_lock(&cookie->lock);
 
-        if (hlist_empty(&cookie->backing_objects))
+        if (!fscache_cookie_enabled(cookie) ||
+            hlist_empty(&cookie->backing_objects))
                 goto nobufs_unlock;
         object = hlist_entry(cookie->backing_objects.first,
                              struct fscache_object, cookie_link);
@@ -551,7 +553,8 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
 
         spin_lock(&cookie->lock);
 
-        if (hlist_empty(&cookie->backing_objects))
+        if (!fscache_cookie_enabled(cookie) ||
+            hlist_empty(&cookie->backing_objects))
                 goto nobufs_unlock;
         object = hlist_entry(cookie->backing_objects.first,
                              struct fscache_object, cookie_link);
@@ -666,7 +669,8 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
 
         spin_lock(&cookie->lock);
 
-        if (hlist_empty(&cookie->backing_objects))
+        if (!fscache_cookie_enabled(cookie) ||
+            hlist_empty(&cookie->backing_objects))
                 goto nobufs_unlock;
         object = hlist_entry(cookie->backing_objects.first,
                              struct fscache_object, cookie_link);
@@ -938,7 +942,8 @@ int __fscache_write_page(struct fscache_cookie *cookie,
         ret = -ENOBUFS;
         spin_lock(&cookie->lock);
 
-        if (hlist_empty(&cookie->backing_objects))
+        if (!fscache_cookie_enabled(cookie) ||
+            hlist_empty(&cookie->backing_objects))
                 goto nobufs;
         object = hlist_entry(cookie->backing_objects.first,
                              struct fscache_object, cookie_link);
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index 24d1d1c5fcaf..cd6e7efd4305 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -39,7 +39,7 @@ 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);
+                                              clp, true);
         dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
                  clp, clp->fscache);
 }
@@ -139,7 +139,7 @@ void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int
         /* create a cache index for looking up filehandles */
         nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
                                                &nfs_fscache_super_index_def,
-                                               nfss);
+                                               nfss, true);
         dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
                  nfss, nfss->fscache);
         return;
@@ -200,7 +200,7 @@ static void nfs_fscache_enable_inode_cookie(struct inode *inode)
                 nfsi->fscache = fscache_acquire_cookie(
                         NFS_SB(sb)->fscache,
                         &nfs_fscache_inode_object_def,
-                        nfsi);
+                        nfsi, true);
 
                 dfprintk(FSCACHE, "NFS: get FH cookie (0x%p/0x%p/0x%p)\n",
                          sb, nfsi, nfsi->fscache);
@@ -327,7 +327,7 @@ void nfs_fscache_reset_inode_cookie(struct inode *inode)
                 nfsi->fscache = fscache_acquire_cookie(
                         nfss->nfs_client->fscache,
                         &nfs_fscache_inode_object_def,
-                        nfsi);
+                        nfsi, true);
 
                 dfprintk(FSCACHE,
                          "NFS: revalidation new cookie (0x%p/0x%p/0x%p/0x%p)\n",