Btrfs: update comments in cache_save_setup

We also don't bother to flush free space cache while with free space
tree.

Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5a7ddcff406b8d2892af6652bac0be64967782b2..1b9ede123ffb7bf356e5ba70eddc3ff6f1c6bd92 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3443,7 +3443,8 @@ again:
                /*
                 * don't bother trying to write stuff out _if_
                 * a) we're not cached,
-                * b) we're with nospace_cache mount option.
+                * b) we're with nospace_cache mount option,
+                * c) we're with v2 space_cache (FREE_SPACE_TREE).
                 */
                dcs = BTRFS_DC_WRITTEN;
                spin_unlock(&block_group->lock);