Btrfs: fix mount -o clear_cache,space_cache=v2

We moved the code for creating the free space tree the first time that
it's enabled, but didn't move the clearing code along with it. This
breaks my (undocumented) intention that `mount -o
clear_cache,space_cache=v2` would clear the free space tree and then
recreate it.

Fixes: 511711af91f2 ("btrfs: don't run delayed references while we are creating the free space tree")
Cc: stable@vger.kernel.org # 4.5+
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 54bc8c7c6bcd387ef48ffc9b69e9771de6e2ca2c..c0bfc6ce5f06e1f86e3aed2c7805b5653e1f9f1a 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3129,6 +3129,18 @@ retry_root_backup:
        if (sb->s_flags & MS_RDONLY)
                return 0;
 
+       if (btrfs_test_opt(fs_info, CLEAR_CACHE) &&
+           btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
+               btrfs_info(fs_info, "clearing free space tree");
+               ret = btrfs_clear_free_space_tree(fs_info);
+               if (ret) {
+                       btrfs_warn(fs_info,
+                                  "failed to clear free space tree: %d", ret);
+                       close_ctree(tree_root);
+                       return ret;
+               }
+       }
+
        if (btrfs_test_opt(tree_root->fs_info, FREE_SPACE_TREE) &&
            !btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
                btrfs_info(fs_info, "creating free space tree");
@@ -3166,18 +3178,6 @@ retry_root_backup:
 
        btrfs_qgroup_rescan_resume(fs_info);
 
-       if (btrfs_test_opt(tree_root->fs_info, CLEAR_CACHE) &&
-           btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
-               btrfs_info(fs_info, "clearing free space tree");
-               ret = btrfs_clear_free_space_tree(fs_info);
-               if (ret) {
-                       btrfs_warn(fs_info,
-                               "failed to clear free space tree: %d", ret);
-                       close_ctree(tree_root);
-                       return ret;
-               }
-       }
-
        if (!fs_info->uuid_root) {
                btrfs_info(fs_info, "creating UUID tree");
                ret = btrfs_create_uuid_tree(fs_info);