btrfs: regression test for nocsum dio read's repair

Commit 2dabb3248453 ("Btrfs: Direct I/O read: Work on sectorsized
blocks") introduced this regression.  It'd cause 'Segmentation
fault' error.

The upstream fix is commit 97bf5a5589aa ("Btrfs: fix segment fault
when doing dio read")

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Filipe Manana <fdmanana@gmail.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
3 files changed