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>

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index c1e0b0c..0b78bf2 100644 (file)
--- 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);