Merge tag 'fscache-20130702' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull FS-Cache updates from David Howells:
 "This contains a number of fixes for various FS-Cache issues plus some
  cleanups.  The commits are, in order:

   1) Provide a system wait_on_atomic_t() and wake_up_atomic_t() sharing
      the bit-wait table (enhancement for #8).

   2) Don't put spin_lock() in a while-condition as spin_lock() may have
      a do {} while(0) wrapper (cleanup).

   3) Symbolically name i_mutex lock classes rather than using numbers
      in CacheFiles (cleanup).

   4) Don't sleep in page release if __GFP_FS is not set (deadlock vs
      ext4).

   5) Uninline fscache_object_init() (cleanup for #7).

   6) Wrap checks on object state (cleanup for #7).

   7) Simplify the object state machine by separating work states from
      wait states.

   8) Simplify cookie retention by objects (NULL pointer deref fix).

   9) Remove unused list_to_page() macro (cleanup).

  10) Make the remaining-pages counter in the retrieval op atomic
      (assertion failure fix).

  11) Don't use spin_is_locked() in assertions (assertion failure fix)"

* tag 'fscache-20130702' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  FS-Cache: Don't use spin_is_locked() in assertions
  FS-Cache: The retrieval remaining-pages counter needs to be atomic_t
  cachefiles: remove unused macro list_to_page()
  FS-Cache: Simplify cookie retention for fscache_objects, fixing oops
  FS-Cache: Fix object state machine to have separate work and wait states
  FS-Cache: Wrap checks on object state
  FS-Cache: Uninline fscache_object_init()
  FS-Cache: Don't sleep in page release if __GFP_FS is not set
  CacheFiles: name i_mutex lock class explicitly
  fs/fscache: remove spin_lock() from the condition in while()
  Add wait_on_atomic_t() and wake_up_atomic_t()

16 files changed, 956 insertions, 822 deletions

diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 746ce532e13..d4c1206af9f 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -13,8 +13,6 @@
 #include <linux/mount.h>
 #include "internal.h"
 
-#define list_to_page(head) (list_entry((head)->prev, struct page, lru))
-
 struct cachefiles_lookup_data {
 	struct cachefiles_xattr	*auxdata;	/* auxiliary data */
 	char			*key;		/* key path */
@@ -212,20 +210,29 @@ static void cachefiles_update_object(struct fscache_object *_object)
 	object = container_of(_object, struct cachefiles_object, fscache);
 	cache = container_of(object->fscache.cache, struct cachefiles_cache,
 			     cache);
+
+	if (!fscache_use_cookie(_object)) {
+		_leave(" [relinq]");
+		return;
+	}
+
 	cookie = object->fscache.cookie;
 
 	if (!cookie->def->get_aux) {
+		fscache_unuse_cookie(_object);
 		_leave(" [no aux]");
 		return;
 	}
 
 	auxdata = kmalloc(2 + 512 + 3, cachefiles_gfp);
 	if (!auxdata) {
+		fscache_unuse_cookie(_object);
 		_leave(" [nomem]");
 		return;
 	}
 
 	auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511);
+	fscache_unuse_cookie(_object);
 	ASSERTCMP(auxlen, <, 511);
 
 	auxdata->len = auxlen + 1;
@@ -263,7 +270,7 @@ static void cachefiles_drop_object(struct fscache_object *_object)
 #endif
 
 	/* delete retired objects */
-	if (object->fscache.state == FSCACHE_OBJECT_RECYCLING &&
+	if (test_bit(FSCACHE_COOKIE_RETIRED, &object->fscache.cookie->flags) &&
 	    _object != cache->cache.fsdef
 	    ) {
 		_debug("- retire object OBJ%x", object->fscache.debug_id);
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 8c01c5fcdf7..25badd1aec5 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -38,7 +38,7 @@ void __cachefiles_printk_object(struct cachefiles_object *object,
 	printk(KERN_ERR "%sobject: OBJ%x\n",
 	       prefix, object->fscache.debug_id);
 	printk(KERN_ERR "%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
-	       prefix, fscache_object_states[object->fscache.state],
+	       prefix, object->fscache.state->name,
 	       object->fscache.flags, work_busy(&object->fscache.work),
 	       object->fscache.events, object->fscache.event_mask);
 	printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
@@ -127,10 +127,10 @@ static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 found_dentry:
 	kdebug("preemptive burial: OBJ%x [%s] %p",
 	       object->fscache.debug_id,
-	       fscache_object_states[object->fscache.state],
+	       object->fscache.state->name,
 	       dentry);
 
-	if (object->fscache.state < FSCACHE_OBJECT_DYING) {
+	if (fscache_object_is_live(&object->fscache)) {
 		printk(KERN_ERR "\n");
 		printk(KERN_ERR "CacheFiles: Error:"
 		       " Can't preemptively bury live object\n");
@@ -192,7 +192,7 @@ try_again:
 	/* an old object from a previous incarnation is hogging the slot - we
 	 * need to wait for it to be destroyed */
 wait_for_old_object:
-	if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
+	if (fscache_object_is_live(&object->fscache)) {
 		printk(KERN_ERR "\n");
 		printk(KERN_ERR "CacheFiles: Error:"
 		       " Unexpected object collision\n");
@@ -836,7 +836,7 @@ static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 	//       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 
 	/* look up the victim */
-	mutex_lock_nested(&dir->d_inode->i_mutex, 1);
+	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 
 	start = jiffies;
 	victim = lookup_one_len(filename, dir, strlen(filename));
diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
index 73b46288b54..2476e516260 100644
--- a/fs/cachefiles/xattr.c
+++ b/fs/cachefiles/xattr.c
@@ -109,13 +109,12 @@ int cachefiles_set_object_xattr(struct cachefiles_object *object,
 	struct dentry *dentry = object->dentry;
 	int ret;
 
-	ASSERT(object->fscache.cookie);
 	ASSERT(dentry);
 
 	_enter("%p,#%d", object, auxdata->len);
 
 	/* attempt to install the cache metadata directly */
-	_debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
+	_debug("SET #%u", auxdata->len);
 
 	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
 			   &auxdata->type, auxdata->len,
@@ -138,13 +137,12 @@ int cachefiles_update_object_xattr(struct cachefiles_object *object,
 	struct dentry *dentry = object->dentry;
 	int ret;
 
-	ASSERT(object->fscache.cookie);
 	ASSERT(dentry);
 
 	_enter("%p,#%d", object, auxdata->len);
 
 	/* attempt to install the cache metadata directly */
-	_debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
+	_debug("SET #%u", auxdata->len);
 
 	ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
 			   &auxdata->type, auxdata->len,
diff --git a/fs/fscache/cache.c b/fs/fscache/cache.c
index b52aed1dca9..f7cff367db7 100644
--- a/fs/fscache/cache.c
+++ b/fs/fscache/cache.c
@@ -115,7 +115,7 @@ struct fscache_cache *fscache_select_cache_for_object(
 				     struct fscache_object, cookie_link);
 
 		cache = object->cache;
-		if (object->state >= FSCACHE_OBJECT_DYING ||
+		if (fscache_object_is_dying(object) ||
 		    test_bit(FSCACHE_IOERROR, &cache->flags))
 			cache = NULL;
 
@@ -224,8 +224,10 @@ int fscache_add_cache(struct fscache_cache *cache,
 	BUG_ON(!ifsdef);
 
 	cache->flags = 0;
-	ifsdef->event_mask = ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
-	ifsdef->state = FSCACHE_OBJECT_ACTIVE;
+	ifsdef->event_mask =
+		((1 << NR_FSCACHE_OBJECT_EVENTS) - 1) &
+		~(1 << FSCACHE_OBJECT_EV_CLEARED);
+	__set_bit(FSCACHE_OBJECT_IS_AVAILABLE, &ifsdef->flags);
 
 	if (!tagname)
 		tagname = cache->identifier;
@@ -330,25 +332,25 @@ static void fscache_withdraw_all_objects(struct fscache_cache *cache,
 {
 	struct fscache_object *object;
 
-	spin_lock(&cache->object_list_lock);
-
 	while (!list_empty(&cache->object_list)) {
-		object = list_entry(cache->object_list.next,
-				    struct fscache_object, cache_link);
-		list_move_tail(&object->cache_link, dying_objects);
+		spin_lock(&cache->object_list_lock);
 
-		_debug("withdraw %p", object->cookie);
+		if (!list_empty(&cache->object_list)) {
+			object = list_entry(cache->object_list.next,
+					    struct fscache_object, cache_link);
+			list_move_tail(&object->cache_link, dying_objects);
 
-		spin_lock(&object->lock);
-		spin_unlock(&cache->object_list_lock);
-		fscache_raise_event(object, FSCACHE_OBJECT_EV_WITHDRAW);
-		spin_unlock(&object->lock);
+			_debug("withdraw %p", object->cookie);
+
+			/* This must be done under object_list_lock to prevent
+			 * a race with fscache_drop_object().
+			 */
+			fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
+		}
 
+		spin_unlock(&cache->object_list_lock);
 		cond_resched();
-		spin_lock(&cache->object_list_lock);
 	}
-
-	spin_unlock(&cache->object_list_lock);
 }
 
 /**
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index e2cba1f60c2..0e91a3c9fdb 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -95,6 +95,11 @@ struct fscache_cookie *__fscache_acquire_cookie(
 	atomic_set(&cookie->usage, 1);
 	atomic_set(&cookie->n_children, 0);
 
+	/* We keep the active count elevated until relinquishment to prevent an
+	 * attempt to wake up every time the object operations queue quiesces.
+	 */
+	atomic_set(&cookie->n_active, 1);
+
 	atomic_inc(&parent->usage);
 	atomic_inc(&parent->n_children);
 
@@ -177,7 +182,6 @@ static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
 
 	cookie->flags =
 		(1 << FSCACHE_COOKIE_LOOKING_UP) |
-		(1 << FSCACHE_COOKIE_CREATING) |
 		(1 << FSCACHE_COOKIE_NO_DATA_YET);
 
 	/* ask the cache to allocate objects for this cookie and its parent
@@ -205,7 +209,7 @@ static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie)
 
 	/* initiate the process of looking up all the objects in the chain
 	 * (done by fscache_initialise_object()) */
-	fscache_enqueue_object(object);
+	fscache_raise_event(object, FSCACHE_OBJECT_EV_NEW_CHILD);
 
 	spin_unlock(&cookie->lock);
 
@@ -285,7 +289,7 @@ static int fscache_alloc_object(struct fscache_cache *cache,
 
 object_already_extant:
 	ret = -ENOBUFS;
-	if (object->state >= FSCACHE_OBJECT_DYING) {
+	if (fscache_object_is_dead(object)) {
 		spin_unlock(&cookie->lock);
 		goto error;
 	}
@@ -321,7 +325,7 @@ static int fscache_attach_object(struct fscache_cookie *cookie,
 	ret = -EEXIST;
 	hlist_for_each_entry(p, &cookie->backing_objects, cookie_link) {
 		if (p->cache == object->cache) {
-			if (p->state >= FSCACHE_OBJECT_DYING)
+			if (fscache_object_is_dying(p))
 				ret = -ENOBUFS;
 			goto cant_attach_object;
 		}
@@ -332,7 +336,7 @@ static int fscache_attach_object(struct fscache_cookie *cookie,
 	hlist_for_each_entry(p, &cookie->parent->backing_objects,
 			     cookie_link) {
 		if (p->cache == object->cache) {
-			if (p->state >= FSCACHE_OBJECT_DYING) {
+			if (fscache_object_is_dying(p)) {
 				ret = -ENOBUFS;
 				spin_unlock(&cookie->parent->lock);
 				goto cant_attach_object;
@@ -400,7 +404,7 @@ void __fscache_invalidate(struct fscache_cookie *cookie)
 			object = hlist_entry(cookie->backing_objects.first,
 					     struct fscache_object,
 					     cookie_link);
-			if (object->state < FSCACHE_OBJECT_DYING)
+			if (fscache_object_is_live(object))
 				fscache_raise_event(
 					object, FSCACHE_OBJECT_EV_INVALIDATE);
 		}
@@ -467,9 +471,7 @@ EXPORT_SYMBOL(__fscache_update_cookie);
  */
 void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
 {
-	struct fscache_cache *cache;
 	struct fscache_object *object;
-	unsigned long event;
 
 	fscache_stat(&fscache_n_relinquishes);
 	if (retire)
@@ -481,8 +483,11 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
 		return;
 	}
 
-	_enter("%p{%s,%p},%d",
-	       cookie, cookie->def->name, cookie->netfs_data, retire);
+	_enter("%p{%s,%p,%d},%d",
+	       cookie, cookie->def->name, cookie->netfs_data,
+	       atomic_read(&cookie->n_active), retire);
+
+	ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
 
 	if (atomic_read(&cookie->n_children) != 0) {
 		printk(KERN_ERR "FS-Cache: Cookie '%s' still has children\n",
@@ -490,62 +495,28 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
 		BUG();
 	}
 
-	/* wait for the cookie to finish being instantiated (or to fail) */
-	if (test_bit(FSCACHE_COOKIE_CREATING, &cookie->flags)) {
-		fscache_stat(&fscache_n_relinquishes_waitcrt);
-		wait_on_bit(&cookie->flags, FSCACHE_COOKIE_CREATING,
-			    fscache_wait_bit, TASK_UNINTERRUPTIBLE);
-	}
-
-	event = retire ? FSCACHE_OBJECT_EV_RETIRE : FSCACHE_OBJECT_EV_RELEASE;
+	/* 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);
 
-try_again:
 	spin_lock(&cookie->lock);
-
-	/* break links with all the active objects */
-	while (!hlist_empty(&cookie->backing_objects)) {
-		int n_reads;
-		object = hlist_entry(cookie->backing_objects.first,
-				     struct fscache_object,
-				     cookie_link);
-
-		_debug("RELEASE OBJ%x", object->debug_id);
-
-		set_bit(FSCACHE_COOKIE_WAITING_ON_READS, &cookie->flags);
-		n_reads = atomic_read(&object->n_reads);
-		if (n_reads) {
-			int n_ops = object->n_ops;
-			int n_in_progress = object->n_in_progress;
-			spin_unlock(&cookie->lock);
-			printk(KERN_ERR "FS-Cache:"
-			       " Cookie '%s' still has %d outstanding reads (%d,%d)\n",
-			       cookie->def->name,
-			       n_reads, n_ops, n_in_progress);
-			wait_on_bit(&cookie->flags, FSCACHE_COOKIE_WAITING_ON_READS,
-				    fscache_wait_bit, TASK_UNINTERRUPTIBLE);
-			printk("Wait finished\n");
-			goto try_again;
-		}
-
-		/* detach each cache object from the object cookie */
-		spin_lock(&object->lock);
-		hlist_del_init(&object->cookie_link);
-
-		cache = object->cache;
-		object->cookie = NULL;
-		fscache_raise_event(object, event);
-		spin_unlock(&object->lock);
-
-		if (atomic_dec_and_test(&cookie->usage))
-			/* the cookie refcount shouldn't be reduced to 0 yet */
-			BUG();
+	hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
+		fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
 	}
+	spin_unlock(&cookie->lock);
 
-	/* detach pointers back to the netfs */
+	/* Wait for cessation of activity requiring access to the netfs (when
+	 * n_active reaches 0).
+	 */
+	if (!atomic_dec_and_test(&cookie->n_active))
+		wait_on_atomic_t(&cookie->n_active, fscache_wait_atomic_t,
+				 TASK_UNINTERRUPTIBLE);
+
+	/* Clear pointers back to the netfs */
 	cookie->netfs_data	= NULL;
 	cookie->def		= NULL;
-
-	spin_unlock(&cookie->lock);
+	BUG_ON(cookie->stores.rnode);
 
 	if (cookie->parent) {
 		ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
@@ -553,7 +524,7 @@ try_again:
 		atomic_dec(&cookie->parent->n_children);
 	}
 
-	/* finally dispose of the cookie */
+	/* Dispose of the netfs's link to the cookie */
 	ASSERTCMP(atomic_read(&cookie->usage), >, 0);
 	fscache_cookie_put(cookie);
 
diff --git a/fs/fscache/fsdef.c b/fs/fscache/fsdef.c
index f5b4baee735..10a2ade0bdf 100644
--- a/fs/fscache/fsdef.c
+++ b/fs/fscache/fsdef.c
@@ -55,6 +55,7 @@ static struct fscache_cookie_def fscache_fsdef_index_def = {
 
 struct fscache_cookie fscache_fsdef_index = {
 	.usage		= ATOMIC_INIT(1),
+	.n_active	= ATOMIC_INIT(1),
 	.lock		= __SPIN_LOCK_UNLOCKED(fscache_fsdef_index.lock),
 	.backing_objects = HLIST_HEAD_INIT,
 	.def		= &fscache_fsdef_index_def,
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index ee38fef4be5..12d505bedb5 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -93,14 +93,11 @@ static inline bool fscache_object_congested(void)
 
 extern int fscache_wait_bit(void *);
 extern int fscache_wait_bit_interruptible(void *);
+extern int fscache_wait_atomic_t(atomic_t *);
 
 /*
  * object.c
  */
-extern const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5];
-
-extern void fscache_withdrawing_object(struct fscache_cache *,
-				       struct fscache_object *);
 extern void fscache_enqueue_object(struct fscache_object *);
 
 /*
@@ -110,8 +107,10 @@ extern void fscache_enqueue_object(struct fscache_object *);
 extern const struct file_operations fscache_objlist_fops;
 
 extern void fscache_objlist_add(struct fscache_object *);
+extern void fscache_objlist_remove(struct fscache_object *);
 #else
 #define fscache_objlist_add(object) do {} while(0)
+#define fscache_objlist_remove(object) do {} while(0)
 #endif
 
 /*
@@ -291,6 +290,10 @@ static inline void fscache_raise_event(struct fscache_object *object,
 				       unsigned event)
 {
 	BUG_ON(event >= NR_FSCACHE_OBJECT_EVENTS);
+#if 0
+	printk("*** fscache_raise_event(OBJ%d{%lx},%x)\n",
+	       object->debug_id, object->event_mask, (1 << event));
+#endif
 	if (!test_and_set_bit(event, &object->events) &&
 	    test_bit(event, &object->event_mask))
 		fscache_enqueue_object(object);
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
index f9d856773f7..7c27907e650 100644
--- a/fs/fscache/main.c
+++ b/fs/fscache/main.c
@@ -205,7 +205,6 @@ int fscache_wait_bit(void *flags)
 	schedule();
 	return 0;
 }
-EXPORT_SYMBOL(fscache_wait_bit);
 
 /*
  * wait_on_bit() sleep function for interruptible waiting
@@ -215,4 +214,12 @@ int fscache_wait_bit_interruptible(void *flags)
 	schedule();
 	return signal_pending(current);
 }
-EXPORT_SYMBOL(fscache_wait_bit_interruptible);
+
+/*
+ * wait_on_atomic_t() sleep function for uninterruptible waiting
+ */
+int fscache_wait_atomic_t(atomic_t *p)
+{
+	schedule();
+	return 0;
+}
diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
index e028b8eb1c4..b1bb6117473 100644
--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -40,6 +40,7 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	/* initialise the primary index cookie */
 	atomic_set(&netfs->primary_index->usage, 1);
 	atomic_set(&netfs->primary_index->n_children, 0);
+	atomic_set(&netfs->primary_index->n_active, 1);
 
 	netfs->primary_index->def		= &fscache_fsdef_netfs_def;
 	netfs->primary_index->parent		= &fscache_fsdef_index;
diff --git a/fs/fscache/object-list.c b/fs/fscache/object-list.c
index f27c89d1788..e1959efad64 100644
--- a/fs/fscache/object-list.c
+++ b/fs/fscache/object-list.c
@@ -70,13 +70,10 @@ void fscache_objlist_add(struct fscache_object *obj)
 	write_unlock(&fscache_object_list_lock);
 }
 
-/**
- * fscache_object_destroy - Note that a cache object is about to be destroyed
- * @object: The object to be destroyed
- *
- * Note the imminent destruction and deallocation of a cache object record.
+/*
+ * Remove an object from the object list.
  */
-void fscache_object_destroy(struct fscache_object *obj)
+void fscache_objlist_remove(struct fscache_object *obj)
 {
 	write_lock(&fscache_object_list_lock);
 
@@ -85,7 +82,6 @@ void fscache_object_destroy(struct fscache_object *obj)
 
 	write_unlock(&fscache_object_list_lock);
 }
-EXPORT_SYMBOL(fscache_object_destroy);
 
 /*
  * find the object in the tree on or after the specified index
@@ -166,15 +162,14 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 {
 	struct fscache_objlist_data *data = m->private;
 	struct fscache_object *obj = v;
+	struct fscache_cookie *cookie;
 	unsigned long config = data->config;
-	uint16_t keylen, auxlen;
 	char _type[3], *type;
-	bool no_cookie;
 	u8 *buf = data->buf, *p;
 
 	if ((unsigned long) v == 1) {
 		seq_puts(m, "OBJECT   PARENT   STAT CHLDN OPS OOP IPR EX READS"
-			 " EM EV F S"
+			 " EM EV FL S"
 			 " | NETFS_COOKIE_DEF TY FL NETFS_DATA");
 		if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
 			      FSCACHE_OBJLIST_CONFIG_AUX))
@@ -193,7 +188,7 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 
 	if ((unsigned long) v == 2) {
 		seq_puts(m, "======== ======== ==== ===== === === === == ====="
-			 " == == = ="
+			 " == == == ="
 			 " | ================ == == ================");
 		if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
 			      FSCACHE_OBJLIST_CONFIG_AUX))
@@ -216,10 +211,11 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 		}							\
 	} while(0)
 
+	cookie = obj->cookie;
 	if (~config) {
-		FILTER(obj->cookie,
+		FILTER(cookie->def,
 		       COOKIE, NOCOOKIE);
-		FILTER(obj->state != FSCACHE_OBJECT_ACTIVE ||
+		FILTER(fscache_object_is_active(obj) ||
 		       obj->n_ops != 0 ||
 		       obj->n_obj_ops != 0 ||
 		       obj->flags ||
@@ -235,10 +231,10 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 	}
 
 	seq_printf(m,
-		   "%8x %8x %s %5u %3u %3u %3u %2u %5u %2lx %2lx %1lx %1x | ",
+		   "%8x %8x %s %5u %3u %3u %3u %2u %5u %2lx %2lx %2lx %1x | ",
 		   obj->debug_id,
 		   obj->parent ? obj->parent->debug_id : -1,
-		   fscache_object_states_short[obj->state],
+		   obj->state->short_name,
 		   obj->n_children,
 		   obj->n_ops,
 		   obj->n_obj_ops,
@@ -250,48 +246,40 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 		   obj->flags,
 		   work_busy(&obj->work));
 
-	no_cookie = true;
-	keylen = auxlen = 0;
-	if (obj->cookie) {
-		spin_lock(&obj->lock);
-		if (obj->cookie) {
-			switch (obj->cookie->def->type) {
-			case 0:
-				type = "IX";
-				break;
-			case 1:
-				type = "DT";
-				break;
-			default:
-				sprintf(_type, "%02u",
-					obj->cookie->def->type);
-				type = _type;
-				break;
-			}
+	if (fscache_use_cookie(obj)) {
+		uint16_t keylen = 0, auxlen = 0;
 
-			seq_printf(m, "%-16s %s %2lx %16p",
-				   obj->cookie->def->name,
-				   type,
-				   obj->cookie->flags,
-				   obj->cookie->netfs_data);
-
-			if (obj->cookie->def->get_key &&
-			    config & FSCACHE_OBJLIST_CONFIG_KEY)
-				keylen = obj->cookie->def->get_key(
-					obj->cookie->netfs_data,
-					buf, 400);
-
-			if (obj->cookie->def->get_aux &&
-			    config & FSCACHE_OBJLIST_CONFIG_AUX)
-				auxlen = obj->cookie->def->get_aux(
-					obj->cookie->netfs_data,
-					buf + keylen, 512 - keylen);
-
-			no_cookie = false;
+		switch (cookie->def->type) {
+		case 0:
+			type = "IX";
+			break;
+		case 1:
+			type = "DT";
+			break;
+		default:
+			sprintf(_type, "%02u", cookie->def->type);
+			type = _type;
+			break;
 		}
-		spin_unlock(&obj->lock);
 
-		if (!no_cookie && (keylen > 0 || auxlen > 0)) {
+		seq_printf(m, "%-16s %s %2lx %16p",
+			   cookie->def->name,
+			   type,
+			   cookie->flags,
+			   cookie->netfs_data);
+
+		if (cookie->def->get_key &&
+		    config & FSCACHE_OBJLIST_CONFIG_KEY)
+			keylen = cookie->def->get_key(cookie->netfs_data,
+						      buf, 400);
+
+		if (cookie->def->get_aux &&
+		    config & FSCACHE_OBJLIST_CONFIG_AUX)
+			auxlen = cookie->def->get_aux(cookie->netfs_data,
+						      buf + keylen, 512 - keylen);
+		fscache_unuse_cookie(obj);
+
+		if (keylen > 0 || auxlen > 0) {
 			seq_printf(m, " ");
 			for (p = buf; keylen > 0; keylen--)
 				seq_printf(m, "%02x", *p++);
@@ -302,12 +290,11 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 					seq_printf(m, "%02x", *p++);
 			}
 		}
-	}
 
-	if (no_cookie)
-		seq_printf(m, "<no_cookie>\n");
-	else
 		seq_printf(m, "\n");
+	} else {
+		seq_printf(m, "<no_netfs>\n");
+	}
 	return 0;
 }
 
diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index 50d41c18021..86d75a60b20 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -15,52 +15,131 @@
 #define FSCACHE_DEBUG_LEVEL COOKIE
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/prefetch.h>
 #include "internal.h"
 
-const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = {
-	[FSCACHE_OBJECT_INIT]		= "OBJECT_INIT",
-	[FSCACHE_OBJECT_LOOKING_UP]	= "OBJECT_LOOKING_UP",
-	[FSCACHE_OBJECT_CREATING]	= "OBJECT_CREATING",
-	[FSCACHE_OBJECT_AVAILABLE]	= "OBJECT_AVAILABLE",
-	[FSCACHE_OBJECT_ACTIVE]		= "OBJECT_ACTIVE",
-	[FSCACHE_OBJECT_INVALIDATING]	= "OBJECT_INVALIDATING",
-	[FSCACHE_OBJECT_UPDATING]	= "OBJECT_UPDATING",
-	[FSCACHE_OBJECT_DYING]		= "OBJECT_DYING",
-	[FSCACHE_OBJECT_LC_DYING]	= "OBJECT_LC_DYING",
-	[FSCACHE_OBJECT_ABORT_INIT]	= "OBJECT_ABORT_INIT",
-	[FSCACHE_OBJECT_RELEASING]	= "OBJECT_RELEASING",
-	[FSCACHE_OBJECT_RECYCLING]	= "OBJECT_RECYCLING",
-	[FSCACHE_OBJECT_WITHDRAWING]	= "OBJECT_WITHDRAWING",
-	[FSCACHE_OBJECT_DEAD]		= "OBJECT_DEAD",
+static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *, int);
+static const struct fscache_state *fscache_kill_dependents(struct fscache_object *, int);
+static const struct fscache_state *fscache_drop_object(struct fscache_object *, int);
+static const struct fscache_state *fscache_initialise_object(struct fscache_object *, int);
+static const struct fscache_state *fscache_invalidate_object(struct fscache_object *, int);
+static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *, int);
+static const struct fscache_state *fscache_kill_object(struct fscache_object *, int);
+static const struct fscache_state *fscache_lookup_failure(struct fscache_object *, int);
+static const struct fscache_state *fscache_look_up_object(struct fscache_object *, int);
+static const struct fscache_state *fscache_object_available(struct fscache_object *, int);
+static const struct fscache_state *fscache_parent_ready(struct fscache_object *, int);
+static const struct fscache_state *fscache_update_object(struct fscache_object *, int);
+
+#define __STATE_NAME(n) fscache_osm_##n
+#define STATE(n) (&__STATE_NAME(n))
+
+/*
+ * Define a work state.  Work states are execution states.  No event processing
+ * is performed by them.  The function attached to a work state returns a
+ * pointer indicating the next state to which the state machine should
+ * transition.  Returning NO_TRANSIT repeats the current state, but goes back
+ * to the scheduler first.
+ */
+#define WORK_STATE(n, sn, f) \
+	const struct fscache_state __STATE_NAME(n) = {			\
+		.name = #n,						\
+		.short_name = sn,					\
+		.work = f						\
+	}
+
+/*
+ * Returns from work states.
+ */
+#define transit_to(state) ({ prefetch(&STATE(state)->work); STATE(state); })
+
+#define NO_TRANSIT ((struct fscache_state *)NULL)
+
+/*
+ * Define a wait state.  Wait states are event processing states.  No execution
+ * is performed by them.  Wait states are just tables of "if event X occurs,
+ * clear it and transition to state Y".  The dispatcher returns to the
+ * scheduler if none of the events in which the wait state has an interest are
+ * currently pending.
+ */
+#define WAIT_STATE(n, sn, ...) \
+	const struct fscache_state __STATE_NAME(n) = {			\
+		.name = #n,						\
+		.short_name = sn,					\
+		.work = NULL,						\
+		.transitions = { __VA_ARGS__, { 0, NULL } }		\
+	}
+
+#define TRANSIT_TO(state, emask) \
+	{ .events = (emask), .transit_to = STATE(state) }
+
+/*
+ * The object state machine.
+ */
+static WORK_STATE(INIT_OBJECT,		"INIT", fscache_initialise_object);
+static WORK_STATE(PARENT_READY,		"PRDY", fscache_parent_ready);
+static WORK_STATE(ABORT_INIT,		"ABRT", fscache_abort_initialisation);
+static WORK_STATE(LOOK_UP_OBJECT,	"LOOK", fscache_look_up_object);
+static WORK_STATE(CREATE_OBJECT,	"CRTO", fscache_look_up_object);
+static WORK_STATE(OBJECT_AVAILABLE,	"AVBL", fscache_object_available);
+static WORK_STATE(JUMPSTART_DEPS,	"JUMP", fscache_jumpstart_dependents);
+
+static WORK_STATE(INVALIDATE_OBJECT,	"INVL", fscache_invalidate_object);
+static WORK_STATE(UPDATE_OBJECT,	"UPDT", fscache_update_object);
+
+static WORK_STATE(LOOKUP_FAILURE,	"LCFL", fscache_lookup_failure);
+static WORK_STATE(KILL_OBJECT,		"KILL", fscache_kill_object);
+static WORK_STATE(KILL_DEPENDENTS,	"KDEP", fscache_kill_dependents);
+static WORK_STATE(DROP_OBJECT,		"DROP", fscache_drop_object);
+static WORK_STATE(OBJECT_DEAD,		"DEAD", (void*)2UL);
+
+static WAIT_STATE(WAIT_FOR_INIT,	"?INI",
+		  TRANSIT_TO(INIT_OBJECT,	1 << FSCACHE_OBJECT_EV_NEW_CHILD));
+
+static WAIT_STATE(WAIT_FOR_PARENT,	"?PRN",
+		  TRANSIT_TO(PARENT_READY,	1 << FSCACHE_OBJECT_EV_PARENT_READY));
+
+static WAIT_STATE(WAIT_FOR_CMD,		"?CMD",
+		  TRANSIT_TO(INVALIDATE_OBJECT,	1 << FSCACHE_OBJECT_EV_INVALIDATE),
+		  TRANSIT_TO(UPDATE_OBJECT,	1 << FSCACHE_OBJECT_EV_UPDATE),
+		  TRANSIT_TO(JUMPSTART_DEPS,	1 << FSCACHE_OBJECT_EV_NEW_CHILD));
+
+static WAIT_STATE(WAIT_FOR_CLEARANCE,	"?CLR",
+		  TRANSIT_TO(KILL_OBJECT,	1 << FSCACHE_OBJECT_EV_CLEARED));
+
+/*
+ * Out-of-band event transition tables.  These are for handling unexpected
+ * events, such as an I/O error.  If an OOB event occurs, the state machine
+ * clears and disables the event and forces a transition to the nominated work
+ * state (acurrently executing work states will complete first).
+ *
+ * In such a situation, object->state remembers the state the machine should
+ * have been in/gone to and returning NO_TRANSIT returns to that.
+ */
+static const struct fscache_transition fscache_osm_init_oob[] = {
+	   TRANSIT_TO(ABORT_INIT,
+		      (1 << FSCACHE_OBJECT_EV_ERROR) |
+		      (1 << FSCACHE_OBJECT_EV_KILL)),
+	   { 0, NULL }
+};
+
+static const struct fscache_transition fscache_osm_lookup_oob[] = {
+	   TRANSIT_TO(LOOKUP_FAILURE,
+		      (1 << FSCACHE_OBJECT_EV_ERROR) |
+		      (1 << FSCACHE_OBJECT_EV_KILL)),
+	   { 0, NULL }
 };
-EXPORT_SYMBOL(fscache_object_states);
-
-const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = {
-	[FSCACHE_OBJECT_INIT]		= "INIT",
-	[FSCACHE_OBJECT_LOOKING_UP]	= "LOOK",
-	[FSCACHE_OBJECT_CREATING]	= "CRTN",
-	[FSCACHE_OBJECT_AVAILABLE]	= "AVBL",
-	[FSCACHE_OBJECT_ACTIVE]		= "ACTV",
-	[FSCACHE_OBJECT_INVALIDATING]	= "INVL",
-	[FSCACHE_OBJECT_UPDATING]	= "UPDT",
-	[FSCACHE_OBJECT_DYING]		= "DYNG",
-	[FSCACHE_OBJECT_LC_DYING]	= "LCDY",
-	[FSCACHE_OBJECT_ABORT_INIT]	= "ABTI",
-	[FSCACHE_OBJECT_RELEASING]	= "RELS",
-	[FSCACHE_OBJECT_RECYCLING]	= "RCYC",
-	[FSCACHE_OBJECT_WITHDRAWING]	= "WTHD",
-	[FSCACHE_OBJECT_DEAD]		= "DEAD",
+
+static const struct fscache_transition fscache_osm_run_oob[] = {
+	   TRANSIT_TO(KILL_OBJECT,
+		      (1 << FSCACHE_OBJECT_EV_ERROR) |
+		      (1 << FSCACHE_OBJECT_EV_KILL)),
+	   { 0, NULL }
 };
 
 static int  fscache_get_object(struct fscache_object *);
 static void fscache_put_object(struct fscache_object *);
-static void fscache_initialise_object(struct fscache_object *);
-static void fscache_lookup_object(struct fscache_object *);
-static void fscache_object_available(struct fscache_object *);
-static void fscache_invalidate_object(struct fscache_object *);
-static void fscache_release_object(struct fscache_object *);
-static void fscache_withdraw_object(struct fscache_object *);
-static void fscache_enqueue_dependents(struct fscache_object *);
+static bool fscache_enqueue_dependents(struct fscache_object *, int);
 static void fscache_dequeue_object(struct fscache_object *);
 
 /*
@@ -75,295 +154,116 @@ static inline void fscache_done_parent_op(struct fscache_object *object)
 	       object->debug_id, parent->debug_id, parent->n_ops);
 
 	spin_lock_nested(&parent->lock, 1);
-	parent->n_ops--;
 	parent->n_obj_ops--;
+	parent->n_ops--;
 	if (parent->n_ops == 0)
 		fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
 	spin_unlock(&parent->lock);
 }
 
 /*
- * Notify netfs of invalidation completion.
+ * Object state machine dispatcher.
  */
-static inline void fscache_invalidation_complete(struct fscache_cookie *cookie)
+static void fscache_object_sm_dispatcher(struct fscache_object *object)
 {
-	if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
-		wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
-}
-
-/*
- * process events that have been sent to an object's state machine
- * - initiates parent lookup
- * - does object lookup
- * - does object creation
- * - does object recycling and retirement