btrfs: fix locking when we put back a delayed ref that's too new

commit d0280996437081dd12ed1e982ac8aeaa62835ec4 upstream.

In __btrfs_run_delayed_refs, when we put back a delayed ref that's too
new, we have already dropped the lock on locked_ref when we set
->processing = 0.

This patch keeps the lock to cover that assignment.

Fixes: d7df2c796d7 (Btrfs: attach delayed ref updates to delayed ref heads)
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 2af08c3de7752ee8d99555a1f5c3ad747c4a2a94..795547c860fcca3669d091112ef50e27ada6ec61 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2520,11 +2520,11 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
                if (ref && ref->seq &&
                    btrfs_check_delayed_seq(fs_info, delayed_refs, ref->seq)) {
                        spin_unlock(&locked_ref->lock);
-                       btrfs_delayed_ref_unlock(locked_ref);
                        spin_lock(&delayed_refs->lock);
                        locked_ref->processing = 0;
                        delayed_refs->num_heads_ready++;
                        spin_unlock(&delayed_refs->lock);
+                       btrfs_delayed_ref_unlock(locked_ref);
                        locked_ref = NULL;
                        cond_resched();
                        count++;