ata: libata-sata: Simplify ata_change_queue_depth()

Commit 141f3d6256e5 ("ata: libata-sata: Fix device queue depth control")
added a struct ata_device argument to ata_change_queue_depth() to
address problems with changing the queue depth of ATA devices managed
through libsas. This was due to problems with ata_scsi_find_dev() which
are now fixed with commit 7f875850f20a ("ata: libata-scsi: Use correct
device no in ata_find_dev()").

Undo some of the changes of commit 141f3d6256e5: remove the added struct
ata_device aregument and use again ata_scsi_find_dev() to find the
target ATA device structure. While doing this, also make sure that
ata_scsi_find_dev() is called with ap->lock held, as it should.

libsas and libata call sites of ata_change_queue_depth() are updated to
match the modified function arguments.

Signed-off-by: Damien Le Moal <[e-mail]>
Reviewed-by: Jason Yan <[e-mail]>
Reviewed-by: John Garry <[e-mail]>

drivers/ata/libata-sata.c

···
 /**
  *	ata_change_queue_depth - Set a device maximum queue depth
  *	@ap: ATA port of the target device
- *	@dev: target ATA device
  *	@sdev: SCSI device to configure queue depth for
  *	@queue_depth: new queue depth
  *
···
  *	and libata.
  *
  */
-int ata_change_queue_depth(struct ata_port *ap, struct ata_device *dev,
-			   struct scsi_device *sdev, int queue_depth)
+int ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
+			   int queue_depth)
 {
+	struct ata_device *dev;
 	unsigned long flags;
 
-	if (!dev || !ata_dev_enabled(dev))
-		return sdev->queue_depth;
+	spin_lock_irqsave(ap->lock, flags);
 
-	if (queue_depth < 1 || queue_depth == sdev->queue_depth)
+	dev = ata_scsi_find_dev(ap, sdev);
+	if (!dev || queue_depth < 1 || queue_depth == sdev->queue_depth) {
+		spin_unlock_irqrestore(ap->lock, flags);
 		return sdev->queue_depth;
+	}
 
 	/* NCQ enabled? */
-	spin_lock_irqsave(ap->lock, flags);
 	dev->flags &= ~ATA_DFLAG_NCQ_OFF;
 	if (queue_depth == 1 || !ata_ncq_enabled(dev)) {
 		dev->flags |= ATA_DFLAG_NCQ_OFF;
 		queue_depth = 1;
 	}
+
 	spin_unlock_irqrestore(ap->lock, flags);
 
 	/* limit and apply queue depth */
···
 {
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
 
-	return ata_change_queue_depth(ap, ata_scsi_find_dev(ap, sdev),
-				      sdev, queue_depth);
+	return ata_change_queue_depth(ap, sdev, queue_depth);
 }
 EXPORT_SYMBOL_GPL(ata_scsi_change_queue_depth);
 

drivers/scsi/libsas/sas_scsi_host.c

···
 	struct domain_device *dev = sdev_to_domain_dev(sdev);
 
 	if (dev_is_sata(dev))
-		return ata_change_queue_depth(dev->sata_dev.ap,
-					      sas_to_ata_dev(dev), sdev, depth);
+		return ata_change_queue_depth(dev->sata_dev.ap, sdev, depth);
 
 	if (!sdev->tagged_supported)
 		depth = 1;

include/linux/libata.h

···
 extern void ata_scsi_slave_destroy(struct scsi_device *sdev);
 extern int ata_scsi_change_queue_depth(struct scsi_device *sdev,
 				       int queue_depth);
-extern int ata_change_queue_depth(struct ata_port *ap, struct ata_device *dev,
-				  struct scsi_device *sdev, int queue_depth);
+extern int ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
+				  int queue_depth);
 extern struct ata_device *ata_dev_pair(struct ata_device *adev);
 extern int ata_do_set_mode(struct ata_link *link, struct ata_device **r_failed_dev);
 extern void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap);