Commit e20fff8a authored by Martin Wilck's avatar Martin Wilck Committed by Martin K. Petersen
Browse files

scsi: core: Don't wait for quiesce in scsi_device_block() 



scsi_device_block() is only called from scsi_target_block(), which calls it
repeatedly for every child device. For targets with many devices, waiting
for every queue to quiesce may cause a substantial delay (we measured more
than 100s delay for blocking a FC rport with 2048 LUNs).

Just call blk_mq_wait_quiesce_done() once from scsi_target_block() after
stopping all queues.

Signed-off-by: default avatarMartin Wilck <mwilck@suse.com>
Link: https://lore.kernel.org/r/20230614103616.31857-6-mwilck@suse.com


Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent d7035b73

drivers/scsi/scsi_lib.c

+10 −7
Original line number Diff line number Diff line
@@ -2771,8 +2771,9 @@ EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait); 
 * @sdev: device to block

 * @data: dummy argument, ignored

 *

 * Pause SCSI command processing on the specified device and wait until all

 * ongoing scsi_queue_rq() calls have finished. May sleep.

 * Pause SCSI command processing on the specified device. Callers must wait

 * until all ongoing scsi_queue_rq() calls have finished after this function

 * returns.

 *

 * Note:

 * This routine transitions the device to the SDEV_BLOCK state (which must be
@@ -2786,16 +2787,14 @@ static void scsi_device_block(struct scsi_device *sdev, void *data) 


	mutex_lock(&sdev->state_mutex);

	err = __scsi_internal_device_block_nowait(sdev);

	if (err == 0) {

	if (err == 0)

		/*

		 * scsi_stop_queue() must be called with the state_mutex

		 * held. Otherwise a simultaneous scsi_start_queue() call

		 * might unquiesce the queue before we quiesce it.

		 */

		scsi_stop_queue(sdev);

		mutex_unlock(&sdev->state_mutex);

		blk_mq_wait_quiesce_done(sdev->request_queue->tag_set);

	} else



	mutex_unlock(&sdev->state_mutex);



	WARN_ONCE(err, "__scsi_internal_device_block_nowait(%s) failed: err = %d\n",
@@ -2894,11 +2893,15 @@ target_block(struct device *dev, void *data) 
void

scsi_target_block(struct device *dev)

{

	struct Scsi_Host *shost = dev_to_shost(dev);



	if (scsi_is_target_device(dev))

		starget_for_each_device(to_scsi_target(dev), NULL,

					scsi_device_block);

	else

		device_for_each_child(dev, NULL, target_block);



	blk_mq_wait_quiesce_done(&shost->tag_set);

}

EXPORT_SYMBOL_GPL(scsi_target_block);