Btrfs: fix enospc problems when deleting a subvol

[~andy/linux] / fs / btrfs / delayed-ref.h

diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index 2b5cb27f986120a5c2df12fc051b386cf3017060..0d7c90c366b629152796c0c717c0e4cd5f50e9b1 100644 (file)
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -179,6 +179,25 @@ int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
                            struct btrfs_delayed_ref_root *delayed_refs,
                            u64 seq);
 
+/*
+ * delayed refs with a ref_seq > 0 must be held back during backref walking.
+ * this only applies to items in one of the fs-trees. for_cow items never need
+ * to be held back, so they won't get a ref_seq number.
+ */
+static inline int need_ref_seq(int for_cow, u64 rootid)
+{
+       if (for_cow)
+               return 0;
+
+       if (rootid == BTRFS_FS_TREE_OBJECTID)
+               return 1;
+
+       if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID)
+               return 1;
+
+       return 0;
+}
+
 /*
  * a node might live in a head or a regular ref, this lets you
  * test for the proper type to use.