Re: [PATCH 6/8] selftests: ublk: forbid multiple data copy modes

Ming Lei
2025-12-11T09:09:18Z

On Wed, Dec 10, 2025 at 10:16:01PM -0700, Caleb Sander Mateos wrote:
> The kublk mock ublk server allows multiple data copy mode arguments to
> be passed on the command line (--zero_copy, --get_data, and --auto_zc).
> The ublk device will be created with all the requested feature flags,
> however kublk will only use one of the modes to interact with request
> data (arbitrarily preferring auto_zc over zero_copy over get_data). To
> clarify the intent of the test, don't allow multiple data copy modes to
> be specified. Don't set UBLK_F_USER_COPY for zero_copy, as it's an
> independent feature. Don't require zero_copy for auto_zc_fallback, as
> only auto_zc is needed. Fix the test cases passing multiple data copy
> mode arguments.
>
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
> ---
> tools/testing/selftests/ublk/kublk.c | 21 ++++++++++++-------
> .../testing/selftests/ublk/test_generic_09.sh | 2 +-
> .../testing/selftests/ublk/test_stress_03.sh | 4 ++--
> .../testing/selftests/ublk/test_stress_04.sh | 2 +-
> .../testing/selftests/ublk/test_stress_05.sh | 10 ++++-----
> 5 files changed, 22 insertions(+), 17 deletions(-)
>
> diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
> index f8fa102a627f..1765c4806523 100644
> --- a/tools/testing/selftests/ublk/kublk.c
> +++ b/tools/testing/selftests/ublk/kublk.c
> @@ -1611,11 +1611,11 @@ int main(int argc, char *argv[])
> break;
> case 'd':
> ctx.queue_depth = strtol(optarg, NULL, 10);
> break;
> case 'z':
> - ctx.flags |= UBLK_F_SUPPORT_ZERO_COPY | UBLK_F_USER_COPY;
> + ctx.flags |= UBLK_F_SUPPORT_ZERO_COPY;
> break;
> case 'r':
> value = strtol(optarg, NULL, 10);
> if (value)
> ctx.flags |= UBLK_F_USER_RECOVERY;
> @@ -1674,17 +1674,22 @@ int main(int argc, char *argv[])
> optind += 1;
> break;
> }
> }
>
> - /* auto_zc_fallback depends on F_AUTO_BUF_REG & F_SUPPORT_ZERO_COPY */
> - if (ctx.auto_zc_fallback &&
> - !((ctx.flags & UBLK_F_AUTO_BUF_REG) &&
> - (ctx.flags & UBLK_F_SUPPORT_ZERO_COPY))) {
> - ublk_err("%s: auto_zc_fallback is set but neither "
> - "F_AUTO_BUF_REG nor F_SUPPORT_ZERO_COPY is enabled\n",
> - __func__);
> + /* auto_zc_fallback depends on F_AUTO_BUF_REG */
> + if (ctx.auto_zc_fallback && !(ctx.flags & UBLK_F_AUTO_BUF_REG)) {
> + ublk_err("%s: auto_zc_fallback is set but F_AUTO_BUF_REG is disabled\n",
> + __func__);
> + return -EINVAL;
> + }
> +
> + if (!!(ctx.flags & UBLK_F_SUPPORT_ZERO_COPY) +
> + !!(ctx.flags & UBLK_F_NEED_GET_DATA) +
> + !!(ctx.flags & UBLK_F_USER_COPY) +
> + !!(ctx.flags & UBLK_F_AUTO_BUF_REG) > 1) {
> + fprintf(stderr, "too many data copy modes specified\n");
> return -EINVAL;
> }

Actually most of them are allowed to co-exist, such as -z/--auto_zc/-u.

>
> i = optind;
> while (i < argc && ctx.nr_files < MAX_BACK_FILES) {
> diff --git a/tools/testing/selftests/ublk/test_generic_09.sh b/tools/testing/selftests/ublk/test_generic_09.sh
> index bb6f77ca5522..145e17b3d2b0 100755
> --- a/tools/testing/selftests/ublk/test_generic_09.sh
> +++ b/tools/testing/selftests/ublk/test_generic_09.sh
> @@ -14,11 +14,11 @@ if ! _have_program fio; then
> exit "$UBLK_SKIP_CODE"
> fi
>
> _prep_test "null" "basic IO test"
>
> -dev_id=$(_add_ublk_dev -t null -z --auto_zc --auto_zc_fallback)
> +dev_id=$(_add_ublk_dev -t null --auto_zc --auto_zc_fallback)
> _check_add_dev $TID $?
>
> # run fio over the two disks
> fio --name=job1 --filename=/dev/ublkb"${dev_id}" --ioengine=libaio --rw=readwrite --iodepth=32 --size=256M > /dev/null 2>&1
> ERR_CODE=$?
> diff --git a/tools/testing/selftests/ublk/test_stress_03.sh b/tools/testing/selftests/ublk/test_stress_03.sh
> index 3ed4c9b2d8c0..8e9f2786ef9c 100755
> --- a/tools/testing/selftests/ublk/test_stress_03.sh
> +++ b/tools/testing/selftests/ublk/test_stress_03.sh
> @@ -36,19 +36,19 @@ wait
>
> if _have_feature "AUTO_BUF_REG"; then
> ublk_io_and_remove 8G -t null -q 4 --auto_zc &
> ublk_io_and_remove 256M -t loop -q 4 --auto_zc "${UBLK_BACKFILES[0]}" &
> ublk_io_and_remove 256M -t stripe -q 4 --auto_zc "${UBLK_BACKFILES[1]}" "${UBLK_BACKFILES[2]}" &
> - ublk_io_and_remove 8G -t null -q 4 -z --auto_zc --auto_zc_fallback &
> + ublk_io_and_remove 8G -t null -q 4 --auto_zc --auto_zc_fallback &
> wait
> fi
>
> if _have_feature "PER_IO_DAEMON"; then
> ublk_io_and_remove 8G -t null -q 4 --auto_zc --nthreads 8 --per_io_tasks &
> ublk_io_and_remove 256M -t loop -q 4 --auto_zc --nthreads 8 --per_io_tasks "${UBLK_BACKFILES[0]}" &
> ublk_io_and_remove 256M -t stripe -q 4 --auto_zc --nthreads 8 --per_io_tasks "${UBLK_BACKFILES[1]}" "${UBLK_BACKFILES[2]}" &
> - ublk_io_and_remove 8G -t null -q 4 -z --auto_zc --auto_zc_fallback --nthreads 8 --per_io_tasks &
> + ublk_io_and_remove 8G -t null -q 4 --auto_zc --auto_zc_fallback --nthreads 8 --per_io_tasks &
> wait
> fi
>
> _cleanup_test "stress"
> _show_result $TID $ERR_CODE
> diff --git a/tools/testing/selftests/ublk/test_stress_04.sh b/tools/testing/selftests/ublk/test_stress_04.sh
> index c7220723b537..6e165a1f90b4 100755
> --- a/tools/testing/selftests/ublk/test_stress_04.sh
> +++ b/tools/testing/selftests/ublk/test_stress_04.sh
> @@ -35,11 +35,11 @@ wait
>
> if _have_feature "AUTO_BUF_REG"; then
> ublk_io_and_kill_daemon 8G -t null -q 4 --auto_zc &
> ublk_io_and_kill_daemon 256M -t loop -q 4 --auto_zc "${UBLK_BACKFILES[0]}" &
> ublk_io_and_kill_daemon 256M -t stripe -q 4 --auto_zc --no_ublk_fixed_fd "${UBLK_BACKFILES[1]}" "${UBLK_BACKFILES[2]}" &
> - ublk_io_and_kill_daemon 8G -t null -q 4 -z --auto_zc --auto_zc_fallback &
> + ublk_io_and_kill_daemon 8G -t null -q 4 --auto_zc --auto_zc_fallback &
> wait
> fi
>
> if _have_feature "PER_IO_DAEMON"; then
> ublk_io_and_kill_daemon 8G -t null -q 4 --auto_zc --nthreads 8 --per_io_tasks &
> diff --git a/tools/testing/selftests/ublk/test_stress_05.sh b/tools/testing/selftests/ublk/test_stress_05.sh
> index 274295061042..09b94c36f2ba 100755
> --- a/tools/testing/selftests/ublk/test_stress_05.sh
> +++ b/tools/testing/selftests/ublk/test_stress_05.sh
> @@ -56,21 +56,21 @@ for reissue in $(seq 0 1); do
> wait
> done
>
> if _have_feature "ZERO_COPY"; then
> for reissue in $(seq 0 1); do
> - ublk_io_and_remove 8G -t null -q 4 -g -z -r 1 -i "$reissue" &
> - ublk_io_and_remove 256M -t loop -q 4 -g -z -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
> + ublk_io_and_remove 8G -t null -q 4 -z -r 1 -i "$reissue" &
> + ublk_io_and_remove 256M -t loop -q 4 -z -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
> wait
> done
> fi
>
> if _have_feature "AUTO_BUF_REG"; then
> for reissue in $(seq 0 1); do
> - ublk_io_and_remove 8G -t null -q 4 -g --auto_zc -r 1 -i "$reissue" &
> - ublk_io_and_remove 256M -t loop -q 4 -g --auto_zc -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
> - ublk_io_and_remove 8G -t null -q 4 -g -z --auto_zc --auto_zc_fallback -r 1 -i "$reissue" &
> + ublk_io_and_remove 8G -t null -q 4 --auto_zc -r 1 -i "$reissue" &
> + ublk_io_and_remove 256M -t loop -q 4 --auto_zc -r 1 -i "$reissue" "${UBLK_BACKFILES[1]}" &
> + ublk_io_and_remove 8G -t null -q 4 --auto_zc --auto_zc_fallback -r 1 -i "$reissue" &

--auto_zc_fallback requires both -z and --auto_zc.

Thanks,
Ming