Btrfs: leave critical region in btrfs_find_all_roots as soon as possible

When delayed refs exist, btrfs_find_all_roots used to hold the delayed ref
mutex way longer than actually required. We ought to drop it immediately
after we're done collecting all the delayed refs.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index cf0df904347fb3ca5d1f3c0825bf18185db18f10..a383c18e74e86eebaa847d756e3493e7ca3c9bfd 100644 (file)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -839,6 +839,7 @@ again:
                        }
                        ret = __add_delayed_refs(head, delayed_ref_seq,
                                                 &prefs_delayed);
+                       mutex_unlock(&head->mutex);
                        if (ret) {
                                spin_unlock(&delayed_refs->lock);
                                goto out;
@@ -932,8 +933,6 @@ again:
        }
 
 out:
-       if (head)
-               mutex_unlock(&head->mutex);
        btrfs_free_path(path);
        while (!list_empty(&prefs)) {
                ref = list_first_entry(&prefs, struct __prelim_ref, list);