5 files changed, 155 insertions, 57 deletions

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);