Commit 0591f040 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: prevent remounting to v1 space cache for subpage mount 



Upstream commit 9f73f1ae ("btrfs: force v2 space cache usage for
subpage mount") forces subpage mount to use v2 cache, to avoid
deprecated v1 cache which doesn't support subpage properly.

But there is a loophole that user can still remount to v1 cache.

The existing check will only give users a warning, but does not really
prevent to do the remount.

Although remounting to v1 will not cause any problems since the v1 cache
will always be marked invalid when mounted with a different page size,
it's still better to prevent v1 cache at all for subpage mounts.

Fixes: 9f73f1ae ("btrfs: force v2 space cache usage for subpage mount")
CC: stable@vger.kernel.org # 5.15+
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 31e70e52

fs/btrfs/super.c

+8 −0
Original line number Diff line number Diff line
@@ -1985,6 +1985,14 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) 
	if (ret)

		goto restore;



	/* V1 cache is not supported for subpage mount. */

	if (fs_info->sectorsize < PAGE_SIZE && btrfs_test_opt(fs_info, SPACE_CACHE)) {

		btrfs_warn(fs_info,

	"v1 space cache is not supported for page size %lu with sectorsize %u",

			   PAGE_SIZE, fs_info->sectorsize);

		ret = -EINVAL;

		goto restore;

	}

	btrfs_remount_begin(fs_info, old_opts, *flags);

	btrfs_resize_thread_pool(fs_info,

		fs_info->thread_pool_size, old_thread_pool_size);