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

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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: Martin Wilck <mwilck@suse.com>
Link: https://lore.kernel.org/r/20230614103616.31857-6-mwilck@suse.com
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Martin Wilck 2023-06-14 12:36:14 +02:00 committed by Martin K. Petersen
parent d7035b73a7
commit e20fff8a1f
1 changed files with 10 additions and 7 deletions
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17
drivers/scsi/scsi_lib.c
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@ -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
@ -2786,17 +2787,15 @@ 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);
mutex_unlock(&sdev->state_mutex);
WARN_ONCE(err, "__scsi_internal_device_block_nowait(%s) failed: err = %d\n",
dev_name(&sdev->sdev_gendev), err);
@ -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);