FS-Cache: Make sure FSCACHE_COOKIE_LOOKING_UP cleared on lookup failure (d461d26d) · Commits · 戴 / test

We must make sure that FSCACHE_COOKIE_LOOKING_UP is cleared on lookup failure (if an object reaches the LC_DYING state), and we should clear it before clearing FSCACHE_COOKIE_CREATING. If this doesn't happen then fscache_wait_for_deferred_lookup() may hold allocation and retrieval operations indefinitely until they're interrupted by signals - which in turn pins the dying object until they go away. Signed-off-by:

David Howells <dhowells@redhat.com>

fs/fscache/object.c

+12 −5

Original line number	Diff line number	Diff line
		@@ -105,6 +105,7 @@ static inline void fscache_done_parent_op(struct fscache_object *object)
		static void fscache_object_state_machine(struct fscache_object *object)
		{
		enum fscache_object_state new_state;
		struct fscache_cookie *cookie;

		ASSERT(object != NULL);

		@@ -158,11 +159,17 @@ static void fscache_object_state_machine(struct fscache_object *object)

		spin_lock(&object->lock);
		object->state = FSCACHE_OBJECT_DYING;
		if (object->cookie &&
		test_and_clear_bit(FSCACHE_COOKIE_CREATING,
		&object->cookie->flags))
		wake_up_bit(&object->cookie->flags,
		cookie = object->cookie;
		if (cookie) {
		if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP,
		&cookie->flags))
		wake_up_bit(&cookie->flags,
		FSCACHE_COOKIE_LOOKING_UP);
		if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
		&cookie->flags))
		wake_up_bit(&cookie->flags,
		FSCACHE_COOKIE_CREATING);
		}
		spin_unlock(&object->lock);

		fscache_done_parent_op(object);

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