btrfs: fix error handling when run_delayed_extent_op fails

commit aa7c8da35d1905d80e840d075f07d26ec90144b5 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 795547c860fcca3669d091112ef50e27ada6ec61..2a2e370399ba40a05524df4d13b3404111d16a20 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2570,7 +2570,10 @@ 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);
                                        btrfs_delayed_ref_unlock(locked_ref);
                                        return ret;