Commit e63d2228 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

ublk: simplify aborting ublk request 



Now ublk_abort_queue() is moved to ublk char device release handler,
meantime our request queue is "quiesced" because either ->canceling was
set from uring_cmd cancel function or all IOs are inflight and can't be
completed by ublk server, things becomes easy much:

- all uring_cmd are done, so we needn't to mark io as UBLK_IO_FLAG_ABORTED
for handling completion from uring_cmd

- ublk char device is closed, no one can hold IO request reference any more,
so we can simply complete this request or requeue it for ublk_nosrv_should_reissue_outstanding.

Reviewed-by: default avatarUday Shankar <ushankar@purestorage.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250416035444.99569-8-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 736b005b

drivers/block/ublk_drv.c

+20 −62
Original line number Diff line number Diff line
@@ -122,15 +122,6 @@ struct ublk_uring_cmd_pdu { 
 */

#define UBLK_IO_FLAG_OWNED_BY_SRV 0x02



/*

 * IO command is aborted, so this flag is set in case of

 * !UBLK_IO_FLAG_ACTIVE.

 *

 * After this flag is observed, any pending or new incoming request

 * associated with this io command will be failed immediately

 */

#define UBLK_IO_FLAG_ABORTED 0x04



/*

 * UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires

 * get data buffer address from ublksrv.
@@ -1083,12 +1074,6 @@ static inline void __ublk_complete_rq(struct request *req) 
	unsigned int unmapped_bytes;

	blk_status_t res = BLK_STS_OK;



	/* called from ublk_abort_queue() code path */

	if (io->flags & UBLK_IO_FLAG_ABORTED) {

		res = BLK_STS_IOERR;

		goto exit;

	}



	/* failed read IO if nothing is read */

	if (!io->res && req_op(req) == REQ_OP_READ)

		io->res = -EIO;
@@ -1138,47 +1123,6 @@ static void ublk_complete_rq(struct kref *ref) 
	__ublk_complete_rq(req);

}



static void ublk_do_fail_rq(struct request *req)

{

	struct ublk_queue *ubq = req->mq_hctx->driver_data;



	if (ublk_nosrv_should_reissue_outstanding(ubq->dev))

		blk_mq_requeue_request(req, false);

	else

		__ublk_complete_rq(req);

}



static void ublk_fail_rq_fn(struct kref *ref)

{

	struct ublk_rq_data *data = container_of(ref, struct ublk_rq_data,

			ref);

	struct request *req = blk_mq_rq_from_pdu(data);



	ublk_do_fail_rq(req);

}



/*

 * Since ublk_rq_task_work_cb always fails requests immediately during

 * exiting, __ublk_fail_req() is only called from abort context during

 * exiting. So lock is unnecessary.

 *

 * Also aborting may not be started yet, keep in mind that one failed

 * request may be issued by block layer again.

 */

static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,

		struct request *req)

{

	WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);



	if (ublk_need_req_ref(ubq)) {

		struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);



		kref_put(&data->ref, ublk_fail_rq_fn);

	} else {

		ublk_do_fail_rq(req);

	}

}



static void ubq_complete_io_cmd(struct ublk_io *io, int res,

				unsigned issue_flags)

{
@@ -1667,10 +1611,26 @@ static void ublk_commit_completion(struct ublk_device *ub, 
		ublk_put_req_ref(ubq, req);

}



static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,

		struct request *req)

{

	WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);



	if (ublk_nosrv_should_reissue_outstanding(ubq->dev))

		blk_mq_requeue_request(req, false);

	else {

		io->res = -EIO;

		__ublk_complete_rq(req);

	}

}



/*

 * Called from ubq_daemon context via cancel fn, meantime quiesce ublk

 * blk-mq queue, so we are called exclusively with blk-mq and ubq_daemon

 * context, so everything is serialized.

 * Called from ublk char device release handler, when any uring_cmd is

 * done, meantime request queue is "quiesced" since all inflight requests

 * can't be completed because ublk server is dead.

 *

 * So no one can hold our request IO reference any more, simply ignore the

 * reference, and complete the request immediately

 */

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

{
@@ -1687,13 +1647,11 @@ static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq) 
			 * will do it

			 */

			rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);

			if (rq && blk_mq_request_started(rq)) {

				io->flags |= UBLK_IO_FLAG_ABORTED;

			if (rq && blk_mq_request_started(rq))

				__ublk_fail_req(ubq, io, rq);

		}

	}

}

}



/* Must be called when queue is frozen */

static void ublk_mark_queue_canceling(struct ublk_queue *ubq)