Commit 59eaa01c authored by Uday Shankar's avatar Uday Shankar Committed by Jens Axboe
Browse files

ublk: support device recovery without I/O queueing 



ublk currently supports the following behaviors on ublk server exit:

A: outstanding I/Os get errors, subsequently issued I/Os get errors
B: outstanding I/Os get errors, subsequently issued I/Os queue
C: outstanding I/Os get reissued, subsequently issued I/Os queue

and the following behaviors for recovery of preexisting block devices by
a future incarnation of the ublk server:

1: ublk devices stopped on ublk server exit (no recovery possible)
2: ublk devices are recoverable using start/end_recovery commands

The userspace interface allows selection of combinations of these
behaviors using flags specified at device creation time, namely:

default behavior: A + 1
UBLK_F_USER_RECOVERY: B + 2
UBLK_F_USER_RECOVERY|UBLK_F_USER_RECOVERY_REISSUE: C + 2

The behavior A + 2 is currently unsupported. Add support for this
behavior under the new flag combination
UBLK_F_USER_RECOVERY|UBLK_F_USER_RECOVERY_FAIL_IO.

Signed-off-by: default avatarUday Shankar <ushankar@purestorage.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241007182419.3263186-5-ushankar@purestorage.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 27b5d417

drivers/block/ublk_drv.c

+63 −15
Original line number Diff line number Diff line
@@ -60,10 +60,12 @@ 
		| UBLK_F_UNPRIVILEGED_DEV \

		| UBLK_F_CMD_IOCTL_ENCODE \

		| UBLK_F_USER_COPY \

		| UBLK_F_ZONED)

		| UBLK_F_ZONED \

		| UBLK_F_USER_RECOVERY_FAIL_IO)



#define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \

		| UBLK_F_USER_RECOVERY_REISSUE)

		| UBLK_F_USER_RECOVERY_REISSUE \

		| UBLK_F_USER_RECOVERY_FAIL_IO)



/* All UBLK_PARAM_TYPE_* should be included here */

#define UBLK_PARAM_TYPE_ALL                                \
@@ -146,6 +148,7 @@ struct ublk_queue { 
	bool force_abort;

	bool timeout;

	bool canceling;

	bool fail_io; /* copy of dev->state == UBLK_S_DEV_FAIL_IO */

	unsigned short nr_io_ready;	/* how many ios setup */

	spinlock_t		cancel_lock;

	struct ublk_device *dev;
@@ -690,7 +693,8 @@ static inline bool ublk_nosrv_should_reissue_outstanding(struct ublk_device *ub) 
 */

static inline bool ublk_nosrv_dev_should_queue_io(struct ublk_device *ub)

{

	return ub->dev_info.flags & UBLK_F_USER_RECOVERY;

	return (ub->dev_info.flags & UBLK_F_USER_RECOVERY) &&

	       !(ub->dev_info.flags & UBLK_F_USER_RECOVERY_FAIL_IO);

}



/*
@@ -700,7 +704,8 @@ static inline bool ublk_nosrv_dev_should_queue_io(struct ublk_device *ub) 
 */

static inline bool ublk_nosrv_should_queue_io(struct ublk_queue *ubq)

{

	return ubq->flags & UBLK_F_USER_RECOVERY;

	return (ubq->flags & UBLK_F_USER_RECOVERY) &&

	       !(ubq->flags & UBLK_F_USER_RECOVERY_FAIL_IO);

}



/*
@@ -714,6 +719,12 @@ static inline bool ublk_nosrv_should_stop_dev(struct ublk_device *ub) 
	return !(ub->dev_info.flags & UBLK_F_USER_RECOVERY);

}



static inline bool ublk_dev_in_recoverable_state(struct ublk_device *ub)

{

	return ub->dev_info.state == UBLK_S_DEV_QUIESCED ||

	       ub->dev_info.state == UBLK_S_DEV_FAIL_IO;

}



static void ublk_free_disk(struct gendisk *disk)

{

	struct ublk_device *ub = disk->private_data;
@@ -1275,6 +1286,10 @@ static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx, 
	struct request *rq = bd->rq;

	blk_status_t res;



	if (unlikely(ubq->fail_io)) {

		return BLK_STS_TARGET;

	}



	/* fill iod to slot in io cmd buffer */

	res = ublk_setup_iod(ubq, rq);

	if (unlikely(res != BLK_STS_OK))
@@ -1625,6 +1640,7 @@ static void ublk_nosrv_work(struct work_struct *work) 
{

	struct ublk_device *ub =

		container_of(work, struct ublk_device, nosrv_work);

	int i;



	if (ublk_nosrv_should_stop_dev(ub)) {

		ublk_stop_dev(ub);
@@ -1634,7 +1650,18 @@ static void ublk_nosrv_work(struct work_struct *work) 
	mutex_lock(&ub->mutex);

	if (ub->dev_info.state != UBLK_S_DEV_LIVE)

		goto unlock;



	if (ublk_nosrv_dev_should_queue_io(ub)) {

		__ublk_quiesce_dev(ub);

	} else {

		blk_mq_quiesce_queue(ub->ub_disk->queue);

		ub->dev_info.state = UBLK_S_DEV_FAIL_IO;

		for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {

			ublk_get_queue(ub, i)->fail_io = true;

		}

		blk_mq_unquiesce_queue(ub->ub_disk->queue);

	}



 unlock:

	mutex_unlock(&ub->mutex);

	ublk_cancel_dev(ub);
@@ -2387,8 +2414,13 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd) 
		return -EPERM;



	/* forbid nonsense combinations of recovery flags */

	if ((info.flags & UBLK_F_USER_RECOVERY_REISSUE) &&

	    !(info.flags & UBLK_F_USER_RECOVERY)) {

	switch (info.flags & UBLK_F_ALL_RECOVERY_FLAGS) {

	case 0:

	case UBLK_F_USER_RECOVERY:

	case (UBLK_F_USER_RECOVERY | UBLK_F_USER_RECOVERY_REISSUE):

	case (UBLK_F_USER_RECOVERY | UBLK_F_USER_RECOVERY_FAIL_IO):

		break;

	default:

		pr_warn("%s: invalid recovery flags %llx\n", __func__,

			info.flags & UBLK_F_ALL_RECOVERY_FLAGS);

		return -EINVAL;
@@ -2729,14 +2761,18 @@ static int ublk_ctrl_start_recovery(struct ublk_device *ub, 
	 *     and related io_uring ctx is freed so file struct of /dev/ublkcX is

	 *     released.

	 *

	 * and one of the following holds

	 *

	 * (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work:

	 *     (a)has quiesced request queue

	 *     (b)has requeued every inflight rqs whose io_flags is ACTIVE

	 *     (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE

	 *     (d)has completed/camceled all ioucmds owned by ther dying process

	 *

	 * (3) UBLK_S_DEV_FAIL_IO is set, which means the queue is not

	 *     quiesced, but all I/O is being immediately errored

	 */

	if (test_bit(UB_STATE_OPEN, &ub->state) ||

			ub->dev_info.state != UBLK_S_DEV_QUIESCED) {

	if (test_bit(UB_STATE_OPEN, &ub->state) || !ublk_dev_in_recoverable_state(ub)) {

		ret = -EBUSY;

		goto out_unlock;

	}
@@ -2760,6 +2796,7 @@ static int ublk_ctrl_end_recovery(struct ublk_device *ub, 
	const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);

	int ublksrv_pid = (int)header->data[0];

	int ret = -EINVAL;

	int i;



	pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n",

			__func__, ub->dev_info.nr_hw_queues, header->dev_id);
@@ -2774,18 +2811,29 @@ static int ublk_ctrl_end_recovery(struct ublk_device *ub, 
	if (ublk_nosrv_should_stop_dev(ub))

		goto out_unlock;



	if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {

	if (!ublk_dev_in_recoverable_state(ub)) {

		ret = -EBUSY;

		goto out_unlock;

	}

	ub->dev_info.ublksrv_pid = ublksrv_pid;

	pr_devel("%s: new ublksrv_pid %d, dev id %d\n",

			__func__, ublksrv_pid, header->dev_id);



	if (ublk_nosrv_dev_should_queue_io(ub)) {

		ub->dev_info.state = UBLK_S_DEV_LIVE;

		blk_mq_unquiesce_queue(ub->ub_disk->queue);

		pr_devel("%s: queue unquiesced, dev id %d.\n",

				__func__, header->dev_id);

		blk_mq_kick_requeue_list(ub->ub_disk->queue);

	} else {

		blk_mq_quiesce_queue(ub->ub_disk->queue);

		ub->dev_info.state = UBLK_S_DEV_LIVE;

		for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {

			ublk_get_queue(ub, i)->fail_io = false;

		}

		blk_mq_unquiesce_queue(ub->ub_disk->queue);

	}



	ret = 0;

 out_unlock:

	mutex_unlock(&ub->mutex);

include/uapi/linux/ublk_cmd.h

+18 −0
Original line number Diff line number Diff line
@@ -147,8 +147,18 @@ 
 */

#define UBLK_F_NEED_GET_DATA (1UL << 2)



/*

 * - Block devices are recoverable if ublk server exits and restarts

 * - Outstanding I/O when ublk server exits is met with errors

 * - I/O issued while there is no ublk server queues

 */

#define UBLK_F_USER_RECOVERY	(1UL << 3)



/*

 * - Block devices are recoverable if ublk server exits and restarts

 * - Outstanding I/O when ublk server exits is reissued

 * - I/O issued while there is no ublk server queues

 */

#define UBLK_F_USER_RECOVERY_REISSUE	(1UL << 4)



/*
@@ -190,10 +200,18 @@ 
 */

#define UBLK_F_ZONED (1ULL << 8)



/*

 * - Block devices are recoverable if ublk server exits and restarts

 * - Outstanding I/O when ublk server exits is met with errors

 * - I/O issued while there is no ublk server is met with errors

 */

#define UBLK_F_USER_RECOVERY_FAIL_IO (1ULL << 9)



/* device state */

#define UBLK_S_DEV_DEAD	0

#define UBLK_S_DEV_LIVE	1

#define UBLK_S_DEV_QUIESCED	2

#define UBLK_S_DEV_FAIL_IO 	3



/* shipped via sqe->cmd of io_uring command */

struct ublksrv_ctrl_cmd {