Re: [PATCH 9/9] selftests: ublk: add generic_06 for covering fault inject

[Uday Shankar <ushankar@purestorage.com>]

On Mon, Apr 14, 2025 at 07:25:50PM +0800, Ming Lei wrote:
> From: Uday Shankar <ushankar@purestorage.com>
> 
> Add one simple fault inject target, and verify if it can be exited in
> expected period.

What "it" refers to is unclear. Maybe say "verify if an application
using ublk device sees an I/O error quickly after the ublk server dies?"

> 
> Signed-off-by: Uday Shankar <ushankar@purestorage.com>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  tools/testing/selftests/ublk/Makefile         |  4 +-
>  tools/testing/selftests/ublk/fault_inject.c   | 98 +++++++++++++++++++
>  tools/testing/selftests/ublk/kublk.c          |  3 +-
>  tools/testing/selftests/ublk/kublk.h          | 12 ++-
>  .../testing/selftests/ublk/test_generic_06.sh | 41 ++++++++
>  5 files changed, 155 insertions(+), 3 deletions(-)
>  create mode 100644 tools/testing/selftests/ublk/fault_inject.c
>  create mode 100755 tools/testing/selftests/ublk/test_generic_06.sh
> 
> diff --git a/tools/testing/selftests/ublk/Makefile b/tools/testing/selftests/ublk/Makefile
> index dddc64036aa1..ec4624a283bc 100644
> --- a/tools/testing/selftests/ublk/Makefile
> +++ b/tools/testing/selftests/ublk/Makefile
> @@ -8,6 +8,7 @@ TEST_PROGS += test_generic_02.sh
>  TEST_PROGS += test_generic_03.sh
>  TEST_PROGS += test_generic_04.sh
>  TEST_PROGS += test_generic_05.sh
> +TEST_PROGS += test_generic_06.sh
>  
>  TEST_PROGS += test_null_01.sh
>  TEST_PROGS += test_null_02.sh
> @@ -31,7 +32,8 @@ TEST_GEN_PROGS_EXTENDED = kublk
>  
>  include ../lib.mk
>  
> -$(TEST_GEN_PROGS_EXTENDED): kublk.c null.c file_backed.c common.c stripe.c
> +$(TEST_GEN_PROGS_EXTENDED): kublk.c null.c file_backed.c common.c stripe.c \
> +	fault_inject.c
>  
>  check:
>  	shellcheck -x -f gcc *.sh
> diff --git a/tools/testing/selftests/ublk/fault_inject.c b/tools/testing/selftests/ublk/fault_inject.c
> new file mode 100644
> index 000000000000..94a8e729ba4c
> --- /dev/null
> +++ b/tools/testing/selftests/ublk/fault_inject.c
> @@ -0,0 +1,98 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Fault injection ublk target. Hack this up however you like for
> + * testing specific behaviors of ublk_drv. Currently is a null target
> + * with a configurable delay before completing each I/O. This delay can
> + * be used to test ublk_drv's handling of I/O outstanding to the ublk
> + * server when it dies.
> + */
> +
> +#include "kublk.h"
> +
> +static int ublk_fault_inject_tgt_init(const struct dev_ctx *ctx,
> +				      struct ublk_dev *dev)
> +{
> +	const struct ublksrv_ctrl_dev_info *info = &dev->dev_info;
> +	unsigned long dev_size = 250UL << 30;
> +
> +	dev->tgt.dev_size = dev_size;
> +	dev->tgt.params = (struct ublk_params) {
> +		.types = UBLK_PARAM_TYPE_BASIC,
> +		.basic = {
> +			.logical_bs_shift	= 9,
> +			.physical_bs_shift	= 12,
> +			.io_opt_shift		= 12,
> +			.io_min_shift		= 9,
> +			.max_sectors		= info->max_io_buf_bytes >> 9,
> +			.dev_sectors		= dev_size >> 9,
> +		},
> +	};
> +
> +	dev->private_data = (void *)(unsigned long)(ctx->fault_inject.delay_us * 1000);
> +	return 0;
> +}
> +
> +static int ublk_fault_inject_queue_io(struct ublk_queue *q, int tag)
> +{
> +	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);
> +	struct io_uring_sqe *sqe;
> +	struct __kernel_timespec ts = {
> +		.tv_nsec = (long long)q->dev->private_data,
> +	};
> +
> +	ublk_queue_alloc_sqes(q, &sqe, 1);
> +	io_uring_prep_timeout(sqe, &ts, 1, 0);
> +	sqe->user_data = build_user_data(tag, ublksrv_get_op(iod), 0, 1);
> +
> +	ublk_queued_tgt_io(q, tag, 1);
> +
> +	return 0;
> +}
> +
> +static void ublk_fault_inject_tgt_io_done(struct ublk_queue *q, int tag,
> +					  const struct io_uring_cqe *cqe)
> +{
> +	const struct ublksrv_io_desc *iod = ublk_get_iod(q, tag);
> +
> +	if (cqe->res != -ETIME)
> +		ublk_err("%s: unexpected cqe res %d\n", __func__, cqe->res);
> +
> +	if (ublk_completed_tgt_io(q, tag))
> +		ublk_complete_io(q, tag, iod->nr_sectors << 9);
> +	else
> +		ublk_err("%s: io not complete after 1 cqe\n", __func__);
> +}
> +
> +static void ublk_fault_inject_cmd_line(struct dev_ctx *ctx, int argc, char *argv[])
> +{
> +	static const struct option longopts[] = {
> +		{ "delay_us", 	1,	NULL,  0  },
> +		{ 0, 0, 0, 0 }
> +	};
> +	int option_idx, opt;
> +
> +	ctx->fault_inject.delay_us = 0;
> +	while ((opt = getopt_long(argc, argv, "",
> +				  longopts, &option_idx)) != -1) {
> +		switch (opt) {
> +		case 0:
> +			if (!strcmp(longopts[option_idx].name, "delay_us"))
> +				ctx->fault_inject.delay_us = strtoll(optarg, NULL, 10);
> +		}
> +	}
> +}
> +
> +static void ublk_fault_inject_usage(const struct ublk_tgt_ops *ops)
> +{
> +	printf("\tfault_inject: [--delay_us us (default 0)]\n");
> +}
> +
> +const struct ublk_tgt_ops fault_inject_tgt_ops = {
> +	.name = "fault_inject",
> +	.init_tgt = ublk_fault_inject_tgt_init,
> +	.queue_io = ublk_fault_inject_queue_io,
> +	.tgt_io_done = ublk_fault_inject_tgt_io_done,
> +	.parse_cmd_line = ublk_fault_inject_cmd_line,
> +	.usage = ublk_fault_inject_usage,
> +};
> diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
> index 0cd6dce3f303..759f06637146 100644
> --- a/tools/testing/selftests/ublk/kublk.c
> +++ b/tools/testing/selftests/ublk/kublk.c
> @@ -12,6 +12,7 @@ static const struct ublk_tgt_ops *tgt_ops_list[] = {
>  	&null_tgt_ops,
>  	&loop_tgt_ops,
>  	&stripe_tgt_ops,
> +	&fault_inject_tgt_ops,
>  };
>  
>  static const struct ublk_tgt_ops *ublk_find_tgt(const char *name)
> @@ -1234,7 +1235,7 @@ static void __cmd_create_help(char *exe, bool recovery)
>  {
>  	int i;
>  
> -	printf("%s %s -t [null|loop|stripe] [-q nr_queues] [-d depth] [-n dev_id]\n",
> +	printf("%s %s -t [null|loop|stripe|fault_inject] [-q nr_queues] [-d depth] [-n dev_id]\n",
>  			exe, recovery ? "recover" : "add");
>  	printf("\t[--foreground] [--quiet] [-z] [--debug_mask mask] [-r 0|1 ] [-g 0|1]\n");
>  	printf("\t[-e 0|1 ] [-i 0|1]\n");
> diff --git a/tools/testing/selftests/ublk/kublk.h b/tools/testing/selftests/ublk/kublk.h
> index 3d2b9f14491c..29571eb296f1 100644
> --- a/tools/testing/selftests/ublk/kublk.h
> +++ b/tools/testing/selftests/ublk/kublk.h
> @@ -68,6 +68,11 @@ struct stripe_ctx {
>  	unsigned int    chunk_size;
>  };
>  
> +struct fault_inject_ctx {
> +	/* fault_inject */
> +	unsigned long   delay_us;
> +};
> +
>  struct dev_ctx {
>  	char tgt_type[16];
>  	unsigned long flags;
> @@ -81,6 +86,9 @@ struct dev_ctx {
>  	unsigned int	fg:1;
>  	unsigned int	recovery:1;
>  
> +	/* fault_inject */
> +	long long	delay_us;
> +
>  	int _evtfd;
>  	int _shmid;
>  
> @@ -88,7 +96,8 @@ struct dev_ctx {
>  	struct ublk_dev *shadow_dev;
>  
>  	union {
> -		struct stripe_ctx  stripe;
> +		struct stripe_ctx 	stripe;
> +		struct fault_inject_ctx fault_inject;
>  	};
>  };
>  
> @@ -384,6 +393,7 @@ static inline int ublk_queue_use_zc(const struct ublk_queue *q)
>  extern const struct ublk_tgt_ops null_tgt_ops;
>  extern const struct ublk_tgt_ops loop_tgt_ops;
>  extern const struct ublk_tgt_ops stripe_tgt_ops;
> +extern const struct ublk_tgt_ops fault_inject_tgt_ops;
>  
>  void backing_file_tgt_deinit(struct ublk_dev *dev);
>  int backing_file_tgt_init(struct ublk_dev *dev);
> diff --git a/tools/testing/selftests/ublk/test_generic_06.sh b/tools/testing/selftests/ublk/test_generic_06.sh
> new file mode 100755
> index 000000000000..b67230c42c84
> --- /dev/null
> +++ b/tools/testing/selftests/ublk/test_generic_06.sh
> @@ -0,0 +1,41 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +
> +. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh
> +
> +TID="generic_06"
> +ERR_CODE=0
> +
> +_prep_test "fault_inject" "fast cleanup when all I/Os of one hctx are in server"
> +
> +# configure ublk server to sleep 2s before completing each I/O
> +dev_id=$(_add_ublk_dev -t fault_inject -q 2 -d 1 --delay_us 2000000)
> +_check_add_dev $TID $?
> +
> +STARTTIME=${SECONDS}
> +
> +dd if=/dev/urandom of=/dev/ublkb${dev_id} oflag=direct bs=4k count=1 status=none > /dev/null 2>&1 &
> +dd_pid=$!
> +
> +__ublk_kill_daemon ${dev_id} "DEAD"
> +
> +wait $dd_pid
> +dd_exitcode=$?
> +
> +ENDTIME=${SECONDS}
> +ELAPSED=$(($ENDTIME - $STARTTIME))
> +
> +# assert that dd sees an error and exits quickly after ublk server is
> +# killed. previously this relied on seeing an I/O timeout and so would
> +# take ~30s
> +if [ $dd_exitcode -eq 0 ]; then
> +        echo "dd unexpectedly exited successfully!"
> +        ERR_CODE=255
> +fi
> +if [ $ELAPSED -ge 5 ]; then
> +        echo "dd took $ELAPSED seconds to exit (>= 5s tolerance)!"
> +        ERR_CODE=255
> +fi
> +
> +_cleanup_test "fault_inject"
> +_show_result $TID $ERR_CODE
> -- 
> 2.47.0
>