Merge tag 'fscache-fixes-20220809' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull fscache updates from David Howells:

 - Fix a cookie access ref leak if a cookie is invalidated a second time
   before the first invalidation is actually processed.

 - Add a tracepoint to log cookie lookup failure

* tag 'fscache-fixes-20220809' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  fscache: add tracepoint when failing cookie
  fscache: don't leak cookie access refs if invalidation is in progress or failed

Author: torvalds

fs/fscache/cookie.c

@@ -263,6 +263,8 @@ void fscache_caching_failed(struct fscache_cookie *cookie)
 {
 	clear_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags);
 	fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_FAILED);
+	trace_fscache_cookie(cookie->debug_id, refcount_read(&cookie->ref),
+				fscache_cookie_failed);
 }
 EXPORT_SYMBOL(fscache_caching_failed);
 
@@ -739,6 +741,9 @@ static void fscache_cookie_state_machine(struct fscache_cookie *cookie)
 		fallthrough;
 
 	case FSCACHE_COOKIE_STATE_FAILED:
+		if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
+			fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
+
 		if (atomic_read(&cookie->n_accesses) != 0)
 			break;
 		if (test_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags)) {
@@ -1063,8 +1068,8 @@ void __fscache_invalidate(struct fscache_cookie *cookie,
 		return;
 
 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
-		__fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);
-		set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags);
+		if (!test_and_set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
+			__fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);
 		fallthrough;
 	case FSCACHE_COOKIE_STATE_CREATING:
 		spin_unlock(&cookie->lock);

include/trace/events/fscache.h

@@ -49,6 +49,7 @@ enum fscache_volume_trace {
 enum fscache_cookie_trace {
 	fscache_cookie_collision,
 	fscache_cookie_discard,
+	fscache_cookie_failed,
 	fscache_cookie_get_attach_object,
 	fscache_cookie_get_end_access,
 	fscache_cookie_get_hash_collision,
@@ -131,6 +132,7 @@ enum fscache_access_trace {
 #define fscache_cookie_traces						\
 	EM(fscache_cookie_collision,		"*COLLIDE*")		\
 	EM(fscache_cookie_discard,		"DISCARD  ")		\
+	EM(fscache_cookie_failed,		"FAILED   ")		\
 	EM(fscache_cookie_get_attach_object,	"GET attch")		\
 	EM(fscache_cookie_get_hash_collision,	"GET hcoll")		\
 	EM(fscache_cookie_get_end_access,	"GQ  endac")		\