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* [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV
@ 2026-01-12 22:04 Yoav Cohen
  2026-01-12 22:05 ` [PATCH v7 1/3] ublk: make ublk_ctrl_stop_dev return void Yoav Cohen
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Yoav Cohen @ 2026-01-12 22:04 UTC (permalink / raw)
  To: Ming Lei, Jens Axboe, linux-block, csander, alex
  Cc: jholzman, omril, Yoav Cohen, Yoav Cohen

Changes since v2:
 - Address Ming Lei’s comments in patch 2:
   - Add a feature flag and some minor comments.
 - Patch 1 unchanged, keeps Reviewed-by

Changes since v3:
 - Address Caleb's comments in patch 2
   - add to kublk.c
   - add to auto features
   - set feature flag to 17

Changes since v4:
 - Selftest added by Ming
 - Move kublk.c change to new selftest commit

Changes since v5:
 - Return -ENXIO when device is going down instead of -EBUSY
 - Update the patch 2 commit msg

Changes since v6:
 - Rebased on top of for-7.0

Ming Lei (1):
  selftests: ublk: add stop command with --safe option

Yoav Cohen (2):
  ublk: make ublk_ctrl_stop_dev return void
  ublk: add UBLK_CMD_TRY_STOP_DEV command

 drivers/block/ublk_drv.c                      | 50 ++++++++++++++--
 include/uapi/linux/ublk_cmd.h                 |  9 ++-
 tools/testing/selftests/ublk/Makefile         |  1 +
 tools/testing/selftests/ublk/kublk.c          | 53 +++++++++++++++++
 tools/testing/selftests/ublk/kublk.h          |  1 +
 .../testing/selftests/ublk/test_generic_16.sh | 57 +++++++++++++++++++
 6 files changed, 165 insertions(+), 6 deletions(-)
 create mode 100755 tools/testing/selftests/ublk/test_generic_16.sh

-- 
2.39.5 (Apple Git-154)


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH v7 1/3] ublk: make ublk_ctrl_stop_dev return void
  2026-01-12 22:04 [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Yoav Cohen
@ 2026-01-12 22:05 ` Yoav Cohen
  2026-01-12 22:05 ` [PATCH v7 2/3] ublk: add UBLK_CMD_TRY_STOP_DEV command Yoav Cohen
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 6+ messages in thread
From: Yoav Cohen @ 2026-01-12 22:05 UTC (permalink / raw)
  To: Ming Lei, Jens Axboe, linux-block, csander, alex
  Cc: jholzman, omril, Yoav Cohen, Yoav Cohen

This function always returns 0, so there is no need to return a value.

Signed-off-by: Yoav Cohen <yoav@nvidia.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/block/ublk_drv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index ec96d5afad7a..73490890242b 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -3459,10 +3459,9 @@ static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
 			header->data[0], header->addr, header->len);
 }
 
-static int ublk_ctrl_stop_dev(struct ublk_device *ub)
+static void ublk_ctrl_stop_dev(struct ublk_device *ub)
 {
 	ublk_stop_dev(ub);
-	return 0;
 }
 
 static int ublk_ctrl_get_dev_info(struct ublk_device *ub,
@@ -3935,7 +3934,8 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
 		ret = ublk_ctrl_start_dev(ub, header);
 		break;
 	case UBLK_CMD_STOP_DEV:
-		ret = ublk_ctrl_stop_dev(ub);
+		ublk_ctrl_stop_dev(ub);
+		ret = 0;
 		break;
 	case UBLK_CMD_GET_DEV_INFO:
 	case UBLK_CMD_GET_DEV_INFO2:
-- 
2.39.5 (Apple Git-154)


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH v7 2/3] ublk: add UBLK_CMD_TRY_STOP_DEV command
  2026-01-12 22:04 [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Yoav Cohen
  2026-01-12 22:05 ` [PATCH v7 1/3] ublk: make ublk_ctrl_stop_dev return void Yoav Cohen
@ 2026-01-12 22:05 ` Yoav Cohen
  2026-01-12 22:05 ` [PATCH v7 3/3] selftests: ublk: add stop command with --safe option Yoav Cohen
  2026-01-12 22:08 ` [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Jens Axboe
  3 siblings, 0 replies; 6+ messages in thread
From: Yoav Cohen @ 2026-01-12 22:05 UTC (permalink / raw)
  To: Ming Lei, Jens Axboe, linux-block, csander, alex
  Cc: jholzman, omril, Yoav Cohen, Yoav Cohen

Add a best-effort stop command, UBLK_CMD_TRY_STOP_DEV, which only stops a
ublk device when it has no active openers.

Unlike UBLK_CMD_STOP_DEV, this command does not disrupt existing users.
New opens are blocked only after disk_openers has reached zero; if the
device is busy, the command returns -EBUSY and leaves it running.

The ub->block_open flag is used only to close a race with an in-progress
open and does not otherwise change open behavior.

Advertise support via the UBLK_F_SAFE_STOP_DEV feature flag.

Signed-off-by: Yoav Cohen <yoav@nvidia.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/block/ublk_drv.c      | 44 +++++++++++++++++++++++++++++++++--
 include/uapi/linux/ublk_cmd.h |  9 ++++++-
 2 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 73490890242b..aaf94d2fb789 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -56,6 +56,7 @@
 #define UBLK_CMD_DEL_DEV_ASYNC	_IOC_NR(UBLK_U_CMD_DEL_DEV_ASYNC)
 #define UBLK_CMD_UPDATE_SIZE	_IOC_NR(UBLK_U_CMD_UPDATE_SIZE)
 #define UBLK_CMD_QUIESCE_DEV	_IOC_NR(UBLK_U_CMD_QUIESCE_DEV)
+#define UBLK_CMD_TRY_STOP_DEV	_IOC_NR(UBLK_U_CMD_TRY_STOP_DEV)
 
 #define UBLK_IO_REGISTER_IO_BUF		_IOC_NR(UBLK_U_IO_REGISTER_IO_BUF)
 #define UBLK_IO_UNREGISTER_IO_BUF	_IOC_NR(UBLK_U_IO_UNREGISTER_IO_BUF)
@@ -76,7 +77,8 @@
 		| UBLK_F_QUIESCE \
 		| UBLK_F_PER_IO_DAEMON \
 		| UBLK_F_BUF_REG_OFF_DAEMON \
-		| (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY) ? UBLK_F_INTEGRITY : 0))
+		| (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY) ? UBLK_F_INTEGRITY : 0) \
+		| UBLK_F_SAFE_STOP_DEV)
 
 #define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \
 		| UBLK_F_USER_RECOVERY_REISSUE \
@@ -243,6 +245,8 @@ struct ublk_device {
 	struct delayed_work	exit_work;
 	struct work_struct	partition_scan_work;
 
+	bool			block_open; /* protected by open_mutex */
+
 	struct ublk_queue       *queues[];
 };
 
@@ -984,6 +988,9 @@ static int ublk_open(struct gendisk *disk, blk_mode_t mode)
 			return -EPERM;
 	}
 
+	if (ub->block_open)
+		return -ENXIO;
+
 	return 0;
 }
 
@@ -3343,7 +3350,8 @@ static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_cmd *header)
 	ub->dev_info.flags |= UBLK_F_CMD_IOCTL_ENCODE |
 		UBLK_F_URING_CMD_COMP_IN_TASK |
 		UBLK_F_PER_IO_DAEMON |
-		UBLK_F_BUF_REG_OFF_DAEMON;
+		UBLK_F_BUF_REG_OFF_DAEMON |
+		UBLK_F_SAFE_STOP_DEV;
 
 	/* GET_DATA isn't needed any more with USER_COPY or ZERO COPY */
 	if (ub->dev_info.flags & (UBLK_F_USER_COPY | UBLK_F_SUPPORT_ZERO_COPY |
@@ -3464,6 +3472,34 @@ static void ublk_ctrl_stop_dev(struct ublk_device *ub)
 	ublk_stop_dev(ub);
 }
 
+static int ublk_ctrl_try_stop_dev(struct ublk_device *ub)
+{
+	struct gendisk *disk;
+	int ret = 0;
+
+	disk = ublk_get_disk(ub);
+	if (!disk)
+		return -ENODEV;
+
+	mutex_lock(&disk->open_mutex);
+	if (disk_openers(disk) > 0) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+	ub->block_open = true;
+	/* release open_mutex as del_gendisk() will reacquire it */
+	mutex_unlock(&disk->open_mutex);
+
+	ublk_ctrl_stop_dev(ub);
+	goto out;
+
+unlock:
+	mutex_unlock(&disk->open_mutex);
+out:
+	ublk_put_disk(disk);
+	return ret;
+}
+
 static int ublk_ctrl_get_dev_info(struct ublk_device *ub,
 		const struct ublksrv_ctrl_cmd *header)
 {
@@ -3859,6 +3895,7 @@ static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
 	case UBLK_CMD_END_USER_RECOVERY:
 	case UBLK_CMD_UPDATE_SIZE:
 	case UBLK_CMD_QUIESCE_DEV:
+	case UBLK_CMD_TRY_STOP_DEV:
 		mask = MAY_READ | MAY_WRITE;
 		break;
 	default:
@@ -3972,6 +4009,9 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
 	case UBLK_CMD_QUIESCE_DEV:
 		ret = ublk_ctrl_quiesce_dev(ub, header);
 		break;
+	case UBLK_CMD_TRY_STOP_DEV:
+		ret = ublk_ctrl_try_stop_dev(ub);
+		break;
 	default:
 		ret = -EOPNOTSUPP;
 		break;
diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 61ac5d8e1078..90f47da4f435 100644
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h
@@ -55,7 +55,8 @@
 	_IOWR('u', 0x15, struct ublksrv_ctrl_cmd)
 #define UBLK_U_CMD_QUIESCE_DEV		\
 	_IOWR('u', 0x16, struct ublksrv_ctrl_cmd)
-
+#define UBLK_U_CMD_TRY_STOP_DEV		\
+	_IOWR('u', 0x17, struct ublksrv_ctrl_cmd)
 /*
  * 64bits are enough now, and it should be easy to extend in case of
  * running out of feature flags
@@ -321,6 +322,12 @@
  */
 #define UBLK_F_INTEGRITY (1ULL << 16)
 
+/*
+ * The device supports the UBLK_CMD_TRY_STOP_DEV command, which
+ * allows stopping the device only if there are no openers.
+ */
+#define UBLK_F_SAFE_STOP_DEV	(1ULL << 17)
+
 /* device state */
 #define UBLK_S_DEV_DEAD	0
 #define UBLK_S_DEV_LIVE	1
-- 
2.39.5 (Apple Git-154)


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH v7 3/3] selftests: ublk: add stop command with --safe option
  2026-01-12 22:04 [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Yoav Cohen
  2026-01-12 22:05 ` [PATCH v7 1/3] ublk: make ublk_ctrl_stop_dev return void Yoav Cohen
  2026-01-12 22:05 ` [PATCH v7 2/3] ublk: add UBLK_CMD_TRY_STOP_DEV command Yoav Cohen
@ 2026-01-12 22:05 ` Yoav Cohen
  2026-01-12 22:15   ` Caleb Sander Mateos
  2026-01-12 22:08 ` [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Jens Axboe
  3 siblings, 1 reply; 6+ messages in thread
From: Yoav Cohen @ 2026-01-12 22:05 UTC (permalink / raw)
  To: Ming Lei, Jens Axboe, linux-block, csander, alex
  Cc: jholzman, omril, Yoav Cohen

From: Ming Lei <ming.lei@redhat.com>

Add 'stop' subcommand to kublk utility that uses the new
UBLK_CMD_TRY_STOP_DEV command when --safe option is specified.
This allows stopping a device only if it has no active openers,
returning -EBUSY otherwise.

Also add test_generic_16.sh to test the new functionality.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 tools/testing/selftests/ublk/Makefile         |  1 +
 tools/testing/selftests/ublk/kublk.c          | 53 +++++++++++++++++
 tools/testing/selftests/ublk/kublk.h          |  1 +
 .../testing/selftests/ublk/test_generic_16.sh | 57 +++++++++++++++++++
 4 files changed, 112 insertions(+)
 create mode 100755 tools/testing/selftests/ublk/test_generic_16.sh

diff --git a/tools/testing/selftests/ublk/Makefile b/tools/testing/selftests/ublk/Makefile
index 036a9f01b464..3a2498089b15 100644
--- a/tools/testing/selftests/ublk/Makefile
+++ b/tools/testing/selftests/ublk/Makefile
@@ -23,6 +23,7 @@ TEST_PROGS += test_generic_12.sh
 TEST_PROGS += test_generic_13.sh
 TEST_PROGS += test_generic_14.sh
 TEST_PROGS += test_generic_15.sh
+TEST_PROGS += test_generic_16.sh
 
 TEST_PROGS += test_null_01.sh
 TEST_PROGS += test_null_02.sh
diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
index d95937dd6167..3472ce7426ba 100644
--- a/tools/testing/selftests/ublk/kublk.c
+++ b/tools/testing/selftests/ublk/kublk.c
@@ -108,6 +108,15 @@ static int ublk_ctrl_stop_dev(struct ublk_dev *dev)
 	return __ublk_ctrl_cmd(dev, &data);
 }
 
+static int ublk_ctrl_try_stop_dev(struct ublk_dev *dev)
+{
+	struct ublk_ctrl_cmd_data data = {
+		.cmd_op	= UBLK_U_CMD_TRY_STOP_DEV,
+	};
+
+	return __ublk_ctrl_cmd(dev, &data);
+}
+
 static int ublk_ctrl_start_dev(struct ublk_dev *dev,
 		int daemon_pid)
 {
@@ -1424,6 +1433,42 @@ static int cmd_dev_del(struct dev_ctx *ctx)
 	return 0;
 }
 
+static int cmd_dev_stop(struct dev_ctx *ctx)
+{
+	int number = ctx->dev_id;
+	struct ublk_dev *dev;
+	int ret;
+
+	if (number < 0) {
+		ublk_err("%s: device id is required\n", __func__);
+		return -EINVAL;
+	}
+
+	dev = ublk_ctrl_init();
+	dev->dev_info.dev_id = number;
+
+	ret = ublk_ctrl_get_info(dev);
+	if (ret < 0)
+		goto fail;
+
+	if (ctx->safe_stop) {
+		ret = ublk_ctrl_try_stop_dev(dev);
+		if (ret < 0)
+			ublk_err("%s: try_stop dev %d failed ret %d\n",
+					__func__, number, ret);
+	} else {
+		ret = ublk_ctrl_stop_dev(dev);
+		if (ret < 0)
+			ublk_err("%s: stop dev %d failed ret %d\n",
+					__func__, number, ret);
+	}
+
+fail:
+	ublk_ctrl_deinit(dev);
+
+	return ret;
+}
+
 static int __cmd_dev_list(struct dev_ctx *ctx)
 {
 	struct ublk_dev *dev = ublk_ctrl_init();
@@ -1487,6 +1532,7 @@ static int cmd_dev_get_features(void)
 		FEAT_NAME(UBLK_F_PER_IO_DAEMON),
 		FEAT_NAME(UBLK_F_BUF_REG_OFF_DAEMON),
 		FEAT_NAME(UBLK_F_INTEGRITY),
+		FEAT_NAME(UBLK_F_SAFE_STOP_DEV)
 	};
 	struct ublk_dev *dev;
 	__u64 features = 0;
@@ -1616,6 +1662,8 @@ static int cmd_dev_help(char *exe)
 
 	printf("%s del [-n dev_id] -a \n", exe);
 	printf("\t -a delete all devices -n delete specified device\n\n");
+	printf("%s stop -n dev_id [--safe]\n", exe);
+	printf("\t --safe only stop if device has no active openers\n\n");
 	printf("%s list [-n dev_id] -a \n", exe);
 	printf("\t -a list all devices, -n list specified device, default -a \n\n");
 	printf("%s features\n", exe);
@@ -1653,6 +1701,7 @@ int main(int argc, char *argv[])
 		{ "pi_offset",		1,	NULL,  0 },
 		{ "csum_type",		1,	NULL,  0 },
 		{ "tag_size",		1,	NULL,  0 },
+		{ "safe",		0,	NULL,  0 },
 		{ 0, 0, 0, 0 }
 	};
 	const struct ublk_tgt_ops *ops = NULL;
@@ -1760,6 +1809,8 @@ int main(int argc, char *argv[])
 			}
 			if (!strcmp(longopts[option_idx].name, "tag_size"))
 				ctx.tag_size = strtoul(optarg, NULL, 0);
+			if (!strcmp(longopts[option_idx].name, "safe"))
+				ctx.safe_stop = 1;
 			break;
 		case '?':
 			/*
@@ -1842,6 +1893,8 @@ int main(int argc, char *argv[])
 		}
 	} else if (!strcmp(cmd, "del"))
 		ret = cmd_dev_del(&ctx);
+	else if (!strcmp(cmd, "stop"))
+		ret = cmd_dev_stop(&ctx);
 	else if (!strcmp(cmd, "list")) {
 		ctx.all = 1;
 		ret = cmd_dev_list(&ctx);
diff --git a/tools/testing/selftests/ublk/kublk.h b/tools/testing/selftests/ublk/kublk.h
index 96c66b337bc0..cb757fd9bf9d 100644
--- a/tools/testing/selftests/ublk/kublk.h
+++ b/tools/testing/selftests/ublk/kublk.h
@@ -83,6 +83,7 @@ struct dev_ctx {
 	__u8 pi_offset;
 	__u8 csum_type;
 	__u8 tag_size;
+	unsigned int	safe_stop:1;
 
 	int _evtfd;
 	int _shmid;
diff --git a/tools/testing/selftests/ublk/test_generic_16.sh b/tools/testing/selftests/ublk/test_generic_16.sh
new file mode 100755
index 000000000000..e08af7b685c9
--- /dev/null
+++ b/tools/testing/selftests/ublk/test_generic_16.sh
@@ -0,0 +1,57 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh
+
+TID="generic_16"
+ERR_CODE=0
+
+_prep_test "null" "stop --safe command"
+
+# Check if SAFE_STOP_DEV feature is supported
+if ! _have_feature "SAFE_STOP_DEV"; then
+	_cleanup_test "null"
+	exit "$UBLK_SKIP_CODE"
+fi
+
+# Test 1: stop --safe on idle device should succeed
+dev_id=$(_add_ublk_dev -t null -q 2 -d 32)
+_check_add_dev $TID $?
+
+# Device is idle (no openers), stop --safe should succeed
+if ! ${UBLK_PROG} stop -n "${dev_id}" --safe; then
+	echo "stop --safe on idle device failed unexpectedly!"
+	ERR_CODE=255
+fi
+
+# Clean up device
+${UBLK_PROG} del -n "${dev_id}" > /dev/null 2>&1
+udevadm settle
+
+# Test 2: stop --safe on device with active opener should fail
+dev_id=$(_add_ublk_dev -t null -q 2 -d 32)
+_check_add_dev $TID $?
+
+# Open device in background (dd reads indefinitely)
+dd if=/dev/ublkb${dev_id} of=/dev/null bs=4k iflag=direct > /dev/null 2>&1 &
+dd_pid=$!
+
+# Give dd time to start
+sleep 0.2
+
+# Device has active opener, stop --safe should fail with -EBUSY
+if ${UBLK_PROG} stop -n "${dev_id}" --safe 2>/dev/null; then
+	echo "stop --safe on busy device succeeded unexpectedly!"
+	ERR_CODE=255
+fi
+
+# Kill dd and clean up
+kill $dd_pid 2>/dev/null
+wait $dd_pid 2>/dev/null
+
+# Now device should be idle, regular delete should work
+${UBLK_PROG} del -n "${dev_id}"
+udevadm settle
+
+_cleanup_test "null"
+_show_result $TID $ERR_CODE
-- 
2.39.5 (Apple Git-154)


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV
  2026-01-12 22:04 [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Yoav Cohen
                   ` (2 preceding siblings ...)
  2026-01-12 22:05 ` [PATCH v7 3/3] selftests: ublk: add stop command with --safe option Yoav Cohen
@ 2026-01-12 22:08 ` Jens Axboe
  3 siblings, 0 replies; 6+ messages in thread
From: Jens Axboe @ 2026-01-12 22:08 UTC (permalink / raw)
  To: Ming Lei, linux-block, csander, alex, Yoav Cohen
  Cc: jholzman, omril, Yoav Cohen


On Tue, 13 Jan 2026 00:04:59 +0200, Yoav Cohen wrote:
> Changes since v2:
>  - Address Ming Lei’s comments in patch 2:
>    - Add a feature flag and some minor comments.
>  - Patch 1 unchanged, keeps Reviewed-by
> 
> Changes since v3:
>  - Address Caleb's comments in patch 2
>    - add to kublk.c
>    - add to auto features
>    - set feature flag to 17
> 
> [...]

Applied, thanks!

[1/3] ublk: make ublk_ctrl_stop_dev return void
      commit: 9e386f49fa269298490b303c423c6af4645f184e
[2/3] ublk: add UBLK_CMD_TRY_STOP_DEV command
      commit: 93ada1b3da398b492c45429cef1a1c9651d5c7ba
[3/3] selftests: ublk: add stop command with --safe option
      commit: 65955a0993a0a9536263fea2eaae8aed496dcc9c

Best regards,
-- 
Jens Axboe




^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH v7 3/3] selftests: ublk: add stop command with --safe option
  2026-01-12 22:05 ` [PATCH v7 3/3] selftests: ublk: add stop command with --safe option Yoav Cohen
@ 2026-01-12 22:15   ` Caleb Sander Mateos
  0 siblings, 0 replies; 6+ messages in thread
From: Caleb Sander Mateos @ 2026-01-12 22:15 UTC (permalink / raw)
  To: Yoav Cohen
  Cc: Ming Lei, Jens Axboe, linux-block, alex, jholzman, omril,
	Yoav Cohen

On Mon, Jan 12, 2026 at 2:06 PM Yoav Cohen <yoav@nvidia.com> wrote:
>
> From: Ming Lei <ming.lei@redhat.com>
>
> Add 'stop' subcommand to kublk utility that uses the new
> UBLK_CMD_TRY_STOP_DEV command when --safe option is specified.
> This allows stopping a device only if it has no active openers,
> returning -EBUSY otherwise.
>
> Also add test_generic_16.sh to test the new functionality.
>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  tools/testing/selftests/ublk/Makefile         |  1 +
>  tools/testing/selftests/ublk/kublk.c          | 53 +++++++++++++++++
>  tools/testing/selftests/ublk/kublk.h          |  1 +
>  .../testing/selftests/ublk/test_generic_16.sh | 57 +++++++++++++++++++
>  4 files changed, 112 insertions(+)
>  create mode 100755 tools/testing/selftests/ublk/test_generic_16.sh
>
> diff --git a/tools/testing/selftests/ublk/Makefile b/tools/testing/selftests/ublk/Makefile
> index 036a9f01b464..3a2498089b15 100644
> --- a/tools/testing/selftests/ublk/Makefile
> +++ b/tools/testing/selftests/ublk/Makefile
> @@ -23,6 +23,7 @@ TEST_PROGS += test_generic_12.sh
>  TEST_PROGS += test_generic_13.sh
>  TEST_PROGS += test_generic_14.sh
>  TEST_PROGS += test_generic_15.sh
> +TEST_PROGS += test_generic_16.sh
>
>  TEST_PROGS += test_null_01.sh
>  TEST_PROGS += test_null_02.sh
> diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
> index d95937dd6167..3472ce7426ba 100644
> --- a/tools/testing/selftests/ublk/kublk.c
> +++ b/tools/testing/selftests/ublk/kublk.c
> @@ -108,6 +108,15 @@ static int ublk_ctrl_stop_dev(struct ublk_dev *dev)
>         return __ublk_ctrl_cmd(dev, &data);
>  }
>
> +static int ublk_ctrl_try_stop_dev(struct ublk_dev *dev)
> +{
> +       struct ublk_ctrl_cmd_data data = {
> +               .cmd_op = UBLK_U_CMD_TRY_STOP_DEV,
> +       };
> +
> +       return __ublk_ctrl_cmd(dev, &data);
> +}
> +
>  static int ublk_ctrl_start_dev(struct ublk_dev *dev,
>                 int daemon_pid)
>  {
> @@ -1424,6 +1433,42 @@ static int cmd_dev_del(struct dev_ctx *ctx)
>         return 0;
>  }
>
> +static int cmd_dev_stop(struct dev_ctx *ctx)
> +{
> +       int number = ctx->dev_id;
> +       struct ublk_dev *dev;
> +       int ret;
> +
> +       if (number < 0) {
> +               ublk_err("%s: device id is required\n", __func__);
> +               return -EINVAL;
> +       }
> +
> +       dev = ublk_ctrl_init();
> +       dev->dev_info.dev_id = number;
> +
> +       ret = ublk_ctrl_get_info(dev);
> +       if (ret < 0)
> +               goto fail;
> +
> +       if (ctx->safe_stop) {
> +               ret = ublk_ctrl_try_stop_dev(dev);
> +               if (ret < 0)
> +                       ublk_err("%s: try_stop dev %d failed ret %d\n",
> +                                       __func__, number, ret);
> +       } else {
> +               ret = ublk_ctrl_stop_dev(dev);
> +               if (ret < 0)
> +                       ublk_err("%s: stop dev %d failed ret %d\n",
> +                                       __func__, number, ret);
> +       }
> +
> +fail:
> +       ublk_ctrl_deinit(dev);
> +
> +       return ret;
> +}
> +
>  static int __cmd_dev_list(struct dev_ctx *ctx)
>  {
>         struct ublk_dev *dev = ublk_ctrl_init();
> @@ -1487,6 +1532,7 @@ static int cmd_dev_get_features(void)
>                 FEAT_NAME(UBLK_F_PER_IO_DAEMON),
>                 FEAT_NAME(UBLK_F_BUF_REG_OFF_DAEMON),
>                 FEAT_NAME(UBLK_F_INTEGRITY),
> +               FEAT_NAME(UBLK_F_SAFE_STOP_DEV)
>         };
>         struct ublk_dev *dev;
>         __u64 features = 0;
> @@ -1616,6 +1662,8 @@ static int cmd_dev_help(char *exe)
>
>         printf("%s del [-n dev_id] -a \n", exe);
>         printf("\t -a delete all devices -n delete specified device\n\n");
> +       printf("%s stop -n dev_id [--safe]\n", exe);
> +       printf("\t --safe only stop if device has no active openers\n\n");
>         printf("%s list [-n dev_id] -a \n", exe);
>         printf("\t -a list all devices, -n list specified device, default -a \n\n");
>         printf("%s features\n", exe);
> @@ -1653,6 +1701,7 @@ int main(int argc, char *argv[])
>                 { "pi_offset",          1,      NULL,  0 },
>                 { "csum_type",          1,      NULL,  0 },
>                 { "tag_size",           1,      NULL,  0 },
> +               { "safe",               0,      NULL,  0 },
>                 { 0, 0, 0, 0 }
>         };
>         const struct ublk_tgt_ops *ops = NULL;
> @@ -1760,6 +1809,8 @@ int main(int argc, char *argv[])
>                         }
>                         if (!strcmp(longopts[option_idx].name, "tag_size"))
>                                 ctx.tag_size = strtoul(optarg, NULL, 0);
> +                       if (!strcmp(longopts[option_idx].name, "safe"))
> +                               ctx.safe_stop = 1;
>                         break;
>                 case '?':
>                         /*
> @@ -1842,6 +1893,8 @@ int main(int argc, char *argv[])
>                 }
>         } else if (!strcmp(cmd, "del"))
>                 ret = cmd_dev_del(&ctx);
> +       else if (!strcmp(cmd, "stop"))
> +               ret = cmd_dev_stop(&ctx);
>         else if (!strcmp(cmd, "list")) {
>                 ctx.all = 1;
>                 ret = cmd_dev_list(&ctx);
> diff --git a/tools/testing/selftests/ublk/kublk.h b/tools/testing/selftests/ublk/kublk.h
> index 96c66b337bc0..cb757fd9bf9d 100644
> --- a/tools/testing/selftests/ublk/kublk.h
> +++ b/tools/testing/selftests/ublk/kublk.h
> @@ -83,6 +83,7 @@ struct dev_ctx {
>         __u8 pi_offset;
>         __u8 csum_type;
>         __u8 tag_size;
> +       unsigned int    safe_stop:1;

Looks like it would make more sense to put this next to the other
bitfields (logging to no_ublk_fixed_fd). Not a big deal, though.

Best,
Caleb

>
>         int _evtfd;
>         int _shmid;
> diff --git a/tools/testing/selftests/ublk/test_generic_16.sh b/tools/testing/selftests/ublk/test_generic_16.sh
> new file mode 100755
> index 000000000000..e08af7b685c9
> --- /dev/null
> +++ b/tools/testing/selftests/ublk/test_generic_16.sh
> @@ -0,0 +1,57 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +
> +. "$(cd "$(dirname "$0")" && pwd)"/test_common.sh
> +
> +TID="generic_16"
> +ERR_CODE=0
> +
> +_prep_test "null" "stop --safe command"
> +
> +# Check if SAFE_STOP_DEV feature is supported
> +if ! _have_feature "SAFE_STOP_DEV"; then
> +       _cleanup_test "null"
> +       exit "$UBLK_SKIP_CODE"
> +fi
> +
> +# Test 1: stop --safe on idle device should succeed
> +dev_id=$(_add_ublk_dev -t null -q 2 -d 32)
> +_check_add_dev $TID $?
> +
> +# Device is idle (no openers), stop --safe should succeed
> +if ! ${UBLK_PROG} stop -n "${dev_id}" --safe; then
> +       echo "stop --safe on idle device failed unexpectedly!"
> +       ERR_CODE=255
> +fi
> +
> +# Clean up device
> +${UBLK_PROG} del -n "${dev_id}" > /dev/null 2>&1
> +udevadm settle
> +
> +# Test 2: stop --safe on device with active opener should fail
> +dev_id=$(_add_ublk_dev -t null -q 2 -d 32)
> +_check_add_dev $TID $?
> +
> +# Open device in background (dd reads indefinitely)
> +dd if=/dev/ublkb${dev_id} of=/dev/null bs=4k iflag=direct > /dev/null 2>&1 &
> +dd_pid=$!
> +
> +# Give dd time to start
> +sleep 0.2
> +
> +# Device has active opener, stop --safe should fail with -EBUSY
> +if ${UBLK_PROG} stop -n "${dev_id}" --safe 2>/dev/null; then
> +       echo "stop --safe on busy device succeeded unexpectedly!"
> +       ERR_CODE=255
> +fi
> +
> +# Kill dd and clean up
> +kill $dd_pid 2>/dev/null
> +wait $dd_pid 2>/dev/null
> +
> +# Now device should be idle, regular delete should work
> +${UBLK_PROG} del -n "${dev_id}"
> +udevadm settle
> +
> +_cleanup_test "null"
> +_show_result $TID $ERR_CODE
> --
> 2.39.5 (Apple Git-154)
>

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-01-12 22:15 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-01-12 22:04 [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Yoav Cohen
2026-01-12 22:05 ` [PATCH v7 1/3] ublk: make ublk_ctrl_stop_dev return void Yoav Cohen
2026-01-12 22:05 ` [PATCH v7 2/3] ublk: add UBLK_CMD_TRY_STOP_DEV command Yoav Cohen
2026-01-12 22:05 ` [PATCH v7 3/3] selftests: ublk: add stop command with --safe option Yoav Cohen
2026-01-12 22:15   ` Caleb Sander Mateos
2026-01-12 22:08 ` [PATCH v7 0/3] ublk: introduce UBLK_CMD_TRY_STOP_DEV Jens Axboe

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