@@ -1914,6 +1914,24 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
btrfs_resize_thread_pool(fs_info,
fs_info->thread_pool_size, old_thread_pool_size);
+ if (btrfs_test_opt(fs_info, FREE_SPACE_TREE) !=
+ btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE) &&
+ ((!sb_rdonly(sb) || *flags & SB_RDONLY))) {
+ btrfs_warn(fs_info,
+ "remount supports changing free space tree only from ro to rw");
+ /*
+ * Make sure free space cache options match the state on disk
+ */
+ if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
+ btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
+ btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
+ }
+ if (btrfs_free_space_cache_v1_active(fs_info)) {
+ btrfs_clear_opt(fs_info->mount_opt, FREE_SPACE_TREE);
+ btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
+ }
+ }
+
if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
goto out;
If the remount is ro->ro, rw->ro, or rw->rw, we will not create or clear the free space tree. This can be surprising, so print a warning to dmesg to make the failure more visible. It is also important to ensure that the space cache options (SPACE_CACHE, FREE_SPACE_TREE) are consistent, so ensure those are set to properly match the current on disk state (which won't be changing). Signed-off-by: Boris Burkov <boris@bur.io> --- fs/btrfs/super.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)