Commit 728cbac5 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

ublk: move device reset into ublk_ch_release() 



ublk_ch_release() is called after ublk char device is closed, when all
uring_cmd are done, so it is perfect fine to move ublk device reset to
ublk_ch_release() from ublk_ctrl_start_recovery().

This way can avoid to grab the exiting daemon task_struct too long.

However, reset of the following ublk IO flags has to be moved until ublk
io_uring queues are ready:

- ubq->canceling

For requeuing IO in case of ublk_nosrv_dev_should_queue_io() before device
is recovered

- ubq->fail_io

For failing IO in case of UBLK_F_USER_RECOVERY_FAIL_IO before device is
recovered

- ublk_io->flags

For preventing using io->cmd

With this way, recovery is simplified a lot.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250416035444.99569-5-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7e26cb69

drivers/block/ublk_drv.c

+72 −49
Original line number Diff line number Diff line
@@ -1074,7 +1074,7 @@ static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu( 


static inline bool ubq_daemon_is_dying(struct ublk_queue *ubq)

{

	return ubq->ubq_daemon->flags & PF_EXITING;

	return !ubq->ubq_daemon || ubq->ubq_daemon->flags & PF_EXITING;

}



/* todo: handle partial completion */
@@ -1470,6 +1470,37 @@ static const struct blk_mq_ops ublk_mq_ops = { 
	.timeout	= ublk_timeout,

};



static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)

{

	int i;



	/* All old ioucmds have to be completed */

	ubq->nr_io_ready = 0;



	/*

	 * old daemon is PF_EXITING, put it now

	 *

	 * It could be NULL in case of closing one quisced device.

	 */

	if (ubq->ubq_daemon)

		put_task_struct(ubq->ubq_daemon);

	/* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */

	ubq->ubq_daemon = NULL;

	ubq->timeout = false;



	for (i = 0; i < ubq->q_depth; i++) {

		struct ublk_io *io = &ubq->ios[i];



		/*

		 * UBLK_IO_FLAG_CANCELED is kept for avoiding to touch

		 * io->cmd

		 */

		io->flags &= UBLK_IO_FLAG_CANCELED;

		io->cmd = NULL;

		io->addr = 0;

	}

}



static int ublk_ch_open(struct inode *inode, struct file *filp)

{

	struct ublk_device *ub = container_of(inode->i_cdev,
@@ -1481,10 +1512,26 @@ static int ublk_ch_open(struct inode *inode, struct file *filp) 
	return 0;

}



static void ublk_reset_ch_dev(struct ublk_device *ub)

{

	int i;



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

		ublk_queue_reinit(ub, ublk_get_queue(ub, i));



	/* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */

	ub->mm = NULL;

	ub->nr_queues_ready = 0;

	ub->nr_privileged_daemon = 0;

}



static int ublk_ch_release(struct inode *inode, struct file *filp)

{

	struct ublk_device *ub = filp->private_data;



	/* all uring_cmd has been done now, reset device & ubq */

	ublk_reset_ch_dev(ub);



	clear_bit(UB_STATE_OPEN, &ub->state);

	return 0;

}
@@ -1831,6 +1878,24 @@ static void ublk_nosrv_work(struct work_struct *work) 
	ublk_cancel_dev(ub);

}



/* reset ublk io_uring queue & io flags */

static void ublk_reset_io_flags(struct ublk_device *ub)

{

	int i, j;



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

		struct ublk_queue *ubq = ublk_get_queue(ub, i);



		/* UBLK_IO_FLAG_CANCELED can be cleared now */

		spin_lock(&ubq->cancel_lock);

		for (j = 0; j < ubq->q_depth; j++)

			ubq->ios[j].flags &= ~UBLK_IO_FLAG_CANCELED;

		spin_unlock(&ubq->cancel_lock);

		ubq->canceling = false;

		ubq->fail_io = false;

	}

}



/* device can only be started after all IOs are ready */

static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)

	__must_hold(&ub->mutex)
@@ -1844,9 +1909,13 @@ static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq) 
		if (capable(CAP_SYS_ADMIN))

			ub->nr_privileged_daemon++;

	}

	if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)



	if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues) {

		/* now we are ready for handling ublk io request */

		ublk_reset_io_flags(ub);

		complete_all(&ub->completion);

	}

}



static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,

		int tag)
@@ -2954,41 +3023,14 @@ static int ublk_ctrl_set_params(struct ublk_device *ub, 
	return ret;

}



static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)

{

	int i;



	WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));



	/* All old ioucmds have to be completed */

	ubq->nr_io_ready = 0;

	/* old daemon is PF_EXITING, put it now */

	put_task_struct(ubq->ubq_daemon);

	/* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */

	ubq->ubq_daemon = NULL;

	ubq->timeout = false;



	for (i = 0; i < ubq->q_depth; i++) {

		struct ublk_io *io = &ubq->ios[i];



		/* forget everything now and be ready for new FETCH_REQ */

		io->flags = 0;

		io->cmd = NULL;

		io->addr = 0;

	}

}



static int ublk_ctrl_start_recovery(struct ublk_device *ub,

		const struct ublksrv_ctrl_cmd *header)

{

	int ret = -EINVAL;

	int i;



	mutex_lock(&ub->mutex);

	if (ublk_nosrv_should_stop_dev(ub))

		goto out_unlock;

	if (!ub->nr_queues_ready)

		goto out_unlock;

	/*

	 * START_RECOVERY is only allowd after:

	 *
@@ -3012,12 +3054,6 @@ static int ublk_ctrl_start_recovery(struct ublk_device *ub, 
		goto out_unlock;

	}

	pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id);

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

		ublk_queue_reinit(ub, ublk_get_queue(ub, i));

	/* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */

	ub->mm = NULL;

	ub->nr_queues_ready = 0;

	ub->nr_privileged_daemon = 0;

	init_completion(&ub->completion);

	ret = 0;

 out_unlock:
@@ -3030,7 +3066,6 @@ static int ublk_ctrl_end_recovery(struct ublk_device *ub, 
{

	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);
@@ -3050,22 +3085,10 @@ static int ublk_ctrl_end_recovery(struct ublk_device *ub, 
		goto out_unlock;

	}

	ub->dev_info.ublksrv_pid = ublksrv_pid;

	ub->dev_info.state = UBLK_S_DEV_LIVE;

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

			__func__, ublksrv_pid, header->dev_id);



	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++) {

		struct ublk_queue *ubq = ublk_get_queue(ub, i);



		ubq->canceling = false;

		ubq->fail_io = false;

	}

	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);



	ret = 0;

 out_unlock:

	mutex_unlock(&ub->mutex);