btrfs: always choose work from prio_head first

In case we do not refill, we can overwrite cur pointer from prio_head
by one from not prioritized head, what looks as something that was
not intended.

This change make we always take works from prio_head first until it's
not empty.

Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Josef Bacik <jbacik@fb.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index c1e0b0caf9cc..0b78bf28ff5d 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -262,18 +262,19 @@ static struct btrfs_work *get_next_work(struct btrfs_worker_thread *worker,
         struct btrfs_work *work = NULL;
         struct list_head *cur = NULL;
 
-        if (!list_empty(prio_head))
+        if (!list_empty(prio_head)) {
                 cur = prio_head->next;
+                goto out;
+        }
 
         smp_mb();
         if (!list_empty(&worker->prio_pending))
                 goto refill;
 
-        if (!list_empty(head))
+        if (!list_empty(head)) {
                 cur = head->next;
-
-        if (cur)
                 goto out;
+        }
 
 refill:
         spin_lock_irq(&worker->lock);