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Commit 6897e3df authored by David Howells's avatar David Howells
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FS-Cache: The object-available state can't rely on the cookie to be available 



The object-available state in the object processing state machine (as
processed by fscache_object_available()) can't rely on the cookie to be
available because the FSCACHE_COOKIE_CREATING bit may have been cleared by
fscache_obtained_object() prior to the object being put into the
FSCACHE_OBJECT_AVAILABLE state.

Clearing the FSCACHE_COOKIE_CREATING bit on a cookie permits
__fscache_relinquish_cookie() to proceed and detach the cookie from the
object.

To deal with this, we don't dereference object->cookie in
fscache_object_available() if the object has already been detached.

In addition, a couple of assertions are added into fscache_drop_object() to
make sure the object is unbound from the cookie before it gets there.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 5753c441

fs/fscache/object.c

+7 −2
Original line number Diff line number Diff line
@@ -158,7 +158,8 @@ static void fscache_object_state_machine(struct fscache_object *object) 


		spin_lock(&object->lock);

		object->state = FSCACHE_OBJECT_DYING;

		if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,

		if (object->cookie &&

		    test_and_clear_bit(FSCACHE_COOKIE_CREATING,

				       &object->cookie->flags))

			wake_up_bit(&object->cookie->flags,

				    FSCACHE_COOKIE_CREATING);
@@ -594,7 +595,8 @@ static void fscache_object_available(struct fscache_object *object) 


	spin_lock(&object->lock);



	if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags))

	if (object->cookie &&

	    test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags))

		wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING);



	fscache_done_parent_op(object);
@@ -631,6 +633,9 @@ static void fscache_drop_object(struct fscache_object *object) 


	_enter("{OBJ%x,%d}", object->debug_id, object->n_children);



	ASSERTCMP(object->cookie, ==, NULL);

	ASSERT(hlist_unhashed(&object->cookie_link));



	spin_lock(&cache->object_list_lock);

	list_del_init(&object->cache_link);

	spin_unlock(&cache->object_list_lock);