btrfs: warn when remount will not change the free space tree (2838d255) · Commits · 戴 / test

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). Reviewed-by:

Josef Bacik <josef@toxicpanda.com> Signed-off-by:

Boris Burkov <boris@bur.io> Reviewed-by:

David Sterba <dsterba@suse.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/super.c

+16 −0

Original line number	Diff line number	Diff line
		@@ -1919,6 +1919,22 @@ 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;

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