Btrfs: add a barrier before a waitqueue_active check



We were missing wakeups on the delayed ref waitqueue due
to races on waitqueue_active.

Signed-off-by: Chris Mason <chris.mason@fusionio.com>

parent e9fbcb42

fs/btrfs/extent-tree.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -5294,6 +5294,7 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
		rb_erase(&head->node.rb_node, &delayed_refs->root);

		delayed_refs->num_entries--;
		smp_mb();
		if (waitqueue_active(&root->fs_info->tree_mod_seq_wait))
		wake_up(&root->fs_info->tree_mod_seq_wait);