btrfs: fix error handling when run_delayed_extent_op fails

In __btrfs_run_delayed_refs, the error path when run_delayed_extent_op
fails sets locked_ref->processing = 0 but doesn't re-increment
delayed_refs->num_heads_ready.  As a result, we end up triggering
the WARN_ON in btrfs_select_ref_head.

Fixes: d7df2c796d7 (Btrfs: attach delayed ref updates to delayed ref heads)
Reported-by: Jon Nelson <jnelson-suse@jamponi.net>
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>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e97302f437a1..5366e50c84c6 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2572,7 +2572,10 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
                                          */
                                         if (must_insert_reserved)
                                                 locked_ref->must_insert_reserved = 1;
+                                        spin_lock(&delayed_refs->lock);
                                         locked_ref->processing = 0;
+                                        delayed_refs->num_heads_ready++;
+                                        spin_unlock(&delayed_refs->lock);
                                         btrfs_debug(fs_info,
                                                     "run_delayed_extent_op returned %d",
                                                     ret);