Re: [PATCH v2 05/13] generic/1226: Add atomic write test using fio crc check verifier

[John Garry <john.g.garry@oracle.com>]

> +touch "$SCRATCH_MNT/f1"
> +awu_min_write=$(_get_atomic_write_unit_min "$SCRATCH_MNT/f1")
> +awu_max_write=$(_get_atomic_write_unit_max "$SCRATCH_MNT/f1")
> +blocksize=$(_max "$awu_min_write" "$((awu_max_write/2))")
> +
> +# XFS can have high awu_max_write due to software fallback. Cap it at 64k

This test fails on xfs due for this reason. software fallback -based 
atomic writes have no serialization against reads or other writes.

Can you cap at atomic write unit max opt? That will mean that we get 
serialization from atomic write HW support.

BTW, to repeat what I said before, it can also fail for atomic write 
bios using HW support, as reads may be split.

See this sample output:

generic/1226 68s ... - output mismatch (see 
/home/opc/xfstests-dev/results//generic/1226.out.bad)
     --- tests/generic/1226.out  2025-06-27 11:26:58.411121674 +0000
     +++ /home/opc/xfstests-dev/results//generic/1226.out.bad 
2025-06-27 14:03:08.933811064 +0000
     @@ -1,2 +1,104 @@
      QA output created by 1226
     +crc32c: verify failed at file /home/opc/mnt/scratch/test-file 
offset 16457728, length 8192 (requested block: offset=16457728, 
length=8192, flags=84)
     +       Expected CRC: 712de900
     +       Received CRC: f872a18d
     +crc32c: verify failed at file /home/opc/mnt/scratch/test-file 
offset 88104960, length 8192 (requested block: offset=88104960, 
length=8192, flags=84)
     +       Expected CRC: 4aaaf009
     +       Received CRC: 2a5770cf
     ...
     (Run 'diff -u /home/opc/xfstests-dev/tests/generic/1226.out 
/home/opc/xfstests-dev/results//generic/1226.out.bad'  to see the entire 
diff)
Ran: generic/1226
Failures: generic/1226
Failed 1 of 1 tests

[root@jgarry-ol9new xfstests-dev]# cat /sys/block/sdi/queue/max_sectors_kb
4
[root@jgarry-ol9new xfstests-dev]#

However, nobody should fiddle with max_sectors_kb, so the test still has 
value.


> +blocksize=$(_min "$blocksize" "65536")
> +
> +fio_config=$tmp.fio
> +fio_out=$tmp.fio.out
> +