Re: [PATCH v4 04/11] generic: Add atomic write test using fio crc check verifier

[John Garry]

On 10/08/2025 14:41, Ojaswin Mujoo wrote:
> This adds atomic write test using fio based on it's crc check verifier.
> fio adds a crc for each data block. If the underlying device supports
> atomic write then it is guaranteed that we will never have a mix data from
> two threads writing on the same physical block.
>
> Avoid doing overlapping parallel atomic writes because it might give
> unexpected results. Use offset_increment=, size= fio options to achieve
> this behavior.

You are not really describing what the test does.

In the first paragraph, you state what fio verify function does and then 
describe what RWF_ATOMIC means when we only use HW support, i.e. 
serialises. In the second you mention that we guarantee no inter-thread 
overlapping writes.

From a glance at the code below, in this test each thread writes to a 
separate part of the file and then verifies no crc corruption. But even 
with atomic=0, I would expect no corruption here.

Thanks,
John

> Co-developed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
> Signed-off-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
> ---
>   tests/generic/1226     | 107 +++++++++++++++++++++++++++++++++++++++++
>   tests/generic/1226.out |   2 +
>   2 files changed, 109 insertions(+)
>   create mode 100755 tests/generic/1226
>   create mode 100644 tests/generic/1226.out
>
> diff --git a/tests/generic/1226 b/tests/generic/1226
> new file mode 100755
> index 00000000..efc360e1
> --- /dev/null
> +++ b/tests/generic/1226
> @@ -0,0 +1,107 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
> +#
> +# FS QA Test 1226
> +#
> +# Validate FS atomic write using fio crc check verifier.
> +#
> +. ./common/preamble
> +. ./common/atomicwrites
> +
> +_begin_fstest auto aio rw atomicwrites
> +
> +_require_scratch_write_atomic
> +_require_odirect
> +_require_aio
> +
> +_scratch_mkfs >> $seqres.full 2>&1
> +_scratch_mount
> +_require_xfs_io_command "falloc"
> +
> +touch "$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" "$((awu_max_write/2))")
> +threads=$(_min "$(($(nproc) * 2 * LOAD_FACTOR))" "100")
> +filesize=$((blocksize * threads * 100))
> +depth=$threads
> +io_size=$((filesize / threads))
> +io_inc=$io_size
> +testfile=$SCRATCH_MNT/test-file
> +
> +fio_config=$tmp.fio
> +fio_out=$tmp.fio.out
> +
> +fio_aw_config=$tmp.aw.fio
> +fio_verify_config=$tmp.verify.fio
> +
> +function create_fio_configs()
> +{
> +	create_fio_aw_config
> +	create_fio_verify_config
> +}
> +
> +function create_fio_verify_config()
> +{
> +cat >$fio_verify_config <<EOF
> +	[verify-job]
> +	direct=1
> +	ioengine=libaio
> +	rw=read
> +	bs=$blocksize
> +	filename=$testfile
> +	size=$filesize
> +	iodepth=$depth
> +	group_reporting=1
> +
> +	verify_only=1
> +	verify=crc32c
> +	verify_fatal=1
> +	verify_state_save=0
> +	verify_write_sequence=0
> +EOF
> +}
> +
> +function create_fio_aw_config()
> +{
> +cat >$fio_aw_config <<EOF
> +	[atomicwrite-job]
> +	direct=1
> +	ioengine=libaio
> +	rw=randwrite
> +	bs=$blocksize
> +	filename=$testfile
> +	size=$io_inc
> +	offset_increment=$io_inc
> +	iodepth=$depth
> +	numjobs=$threads
> +	group_reporting=1
> +	atomic=1
> +
> +	verify_state_save=0
> +	verify=crc32c
> +	do_verify=0
> +EOF
> +}
> +
> +create_fio_configs
> +_require_fio $fio_aw_config
> +
> +cat $fio_aw_config >> $seqres.full
> +cat $fio_verify_config >> $seqres.full
> +
> +$XFS_IO_PROG -fc "falloc 0 $filesize" $testfile >> $seqres.full
> +
> +$FIO_PROG $fio_aw_config >> $seqres.full
> +ret1=$?
> +$FIO_PROG $fio_verify_config >> $seqres.full
> +ret2=$?
> +
> +[[ $ret1 -eq 0 && $ret2 -eq 0 ]] || _fail "fio with atomic write failed"
> +
> +# success, all done
> +echo Silence is golden
> +status=0
> +exit
> diff --git a/tests/generic/1226.out b/tests/generic/1226.out
> new file mode 100644
> index 00000000..6dce0ea5
> --- /dev/null
> +++ b/tests/generic/1226.out
> @@ -0,0 +1,2 @@
> +QA output created by 1226
> +Silence is golden