scsi: core: Only process PM requests if rpm_status != RPM_ACTIVE

Instead of submitting all SCSI commands submitted with scsi_execute() to a
SCSI device if rpm_status != RPM_ACTIVE, only submit RQF_PM (power
management requests) if rpm_status != RPM_ACTIVE. This patch makes the SCSI
core handle the runtime power management status (rpm_status) as it should
be handled.

Link: https://lore.kernel.org/r/20201209052951.16136-7-bvanassche@acm.org
Cc: Can Guo <cang@codeaurora.org>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Martin Kepplinger <martin.kepplinger@puri.sm>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_lib.c

@@ -249,7 +249,8 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 
 	req = blk_get_request(sdev->request_queue,
 			data_direction == DMA_TO_DEVICE ?
-			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, BLK_MQ_REQ_PREEMPT);
+			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN,
+			rq_flags & RQF_PM ? BLK_MQ_REQ_PM : 0);
 	if (IS_ERR(req))
 		return ret;
 	rq = scsi_req(req);
@@ -1206,6 +1207,8 @@ static blk_status_t
 scsi_device_state_check(struct scsi_device *sdev, struct request *req)
 {
 	switch (sdev->sdev_state) {
+	case SDEV_CREATED:
+		return BLK_STS_OK;
 	case SDEV_OFFLINE:
 	case SDEV_TRANSPORT_OFFLINE:
 		/*
@@ -1232,18 +1235,18 @@ scsi_device_state_check(struct scsi_device *sdev, struct request *req)
 		return BLK_STS_RESOURCE;
 	case SDEV_QUIESCE:
 		/*
-		 * If the devices is blocked we defer normal commands.
+		 * If the device is blocked we only accept power management
+		 * commands.
 		 */
-		if (req && !(req->rq_flags & RQF_PREEMPT))
+		if (req && WARN_ON_ONCE(!(req->rq_flags & RQF_PM)))
 			return BLK_STS_RESOURCE;
 		return BLK_STS_OK;
 	default:
 		/*
 		 * For any other not fully online state we only allow
-		 * special commands.  In particular any user initiated
-		 * command is not allowed.
+		 * power management commands.
 		 */
-		if (req && !(req->rq_flags & RQF_PREEMPT))
+		if (req && !(req->rq_flags & RQF_PM))
 			return BLK_STS_IOERR;
 		return BLK_STS_OK;
 	}
@@ -2517,15 +2520,13 @@ void sdev_evt_send_simple(struct scsi_device *sdev,
 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
 
 /**
- *	scsi_device_quiesce - Block user issued commands.
+ *	scsi_device_quiesce - Block all commands except power management.
  *	@sdev:	scsi device to quiesce.
  *
  *	This works by trying to transition to the SDEV_QUIESCE state
  *	(which must be a legal transition).  When the device is in this
- *	state, only special requests will be accepted, all others will
- *	be deferred.  Since special requests may also be requeued requests,
- *	a successful return doesn't guarantee the device will be
- *	totally quiescent.
+ *	state, only power management requests will be accepted, all others will
+ *	be deferred.
  *
  *	Must be called with user context, may sleep.
  *
@@ -2587,12 +2588,12 @@ void scsi_device_resume(struct scsi_device *sdev)
 	 * device deleted during suspend)
 	 */
 	mutex_lock(&sdev->state_mutex);
+	if (sdev->sdev_state == SDEV_QUIESCE)
+		scsi_device_set_state(sdev, SDEV_RUNNING);
 	if (sdev->quiesced_by) {
 		sdev->quiesced_by = NULL;
 		blk_clear_pm_only(sdev->request_queue);
 	}
-	if (sdev->sdev_state == SDEV_QUIESCE)
-		scsi_device_set_state(sdev, SDEV_RUNNING);
 	mutex_unlock(&sdev->state_mutex);
 }
 EXPORT_SYMBOL(scsi_device_resume);