On Thu, Feb 11, 2021 at 04:38:28PM +0800, Su Yue wrote:
> User reported that btrfs-progs misc-tests/028-superblock-recover fails:
> [TEST/misc] 028-superblock-recover
> unexpected success: mounted fs with corrupted superblock
> test failed for case 028-superblock-recover
>
> The test case expects that a broken image with bad superblock will be
> rejected to be mounted. However, the test image just passed csum check
> of superblock and was successfully mounted.
>
> Commit 55fc29bed8dd ("btrfs: use cached value of fs_info::csum_size
> everywhere") replaces all calls to btrfs_super_csum_size by
> fs_info::csum_size. The calls include the place where fs_info->csum_size
> is not initialized. So btrfs_check_super_csum() passes because memcmp()
> with len 0 always returns 0.
>
> Fix it by caching csum size in btrfs_fs_info::csum_size once we know the
> csum type in superblock is valid in open_ctree().
>
> Link: https://github.com/kdave/btrfs-progs/issues/250
> Fixes: 55fc29bed8dd ("btrfs: use cached value of fs_info::csum_size
> everywhere")
That's a new commit in 5.11 and the bug looks serious, I'll need to send
one more pull request. Thanks for the fix.
