From: Omar Sandoval osandov@fb.com
commit e7a04894c766daa4248cb736efee93550f2d5872 upstream.
btrfs_lookup_and_bind_dio_csum() does pointer arithmetic which assumes 32-bit checksums. If using a larger checksum, this leads to spurious failures when a direct I/O read crosses a stripe. This is easy to reproduce:
# mkfs.btrfs -f --checksum blake2 -d raid0 /dev/vdc /dev/vdd ... # mount /dev/vdc /mnt # cd /mnt # dd if=/dev/urandom of=foo bs=1M count=1 status=none # dd if=foo of=/dev/null bs=1M iflag=direct status=none dd: error reading 'foo': Input/output error # dmesg | tail -1 [ 135.821568] BTRFS warning (device vdc): csum failed root 5 ino 257 off 421888 ...
Fix it by using the actual checksum size.
Fixes: 1e25a2e3ca0d ("btrfs: don't assume ordered sums to be 4 bytes") CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Omar Sandoval osandov@fb.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/inode.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8444,6 +8444,7 @@ static inline blk_status_t btrfs_lookup_ { struct btrfs_io_bio *io_bio = btrfs_io_bio(bio); struct btrfs_io_bio *orig_io_bio = btrfs_io_bio(dip->orig_bio); + u16 csum_size; blk_status_t ret;
/* @@ -8463,7 +8464,8 @@ static inline blk_status_t btrfs_lookup_
file_offset -= dip->logical_offset; file_offset >>= inode->i_sb->s_blocksize_bits; - io_bio->csum = (u8 *)(((u32 *)orig_io_bio->csum) + file_offset); + csum_size = btrfs_super_csum_size(btrfs_sb(inode->i_sb)->super_copy); + io_bio->csum = orig_io_bio->csum + csum_size * file_offset;
return 0; }