[PATCH v2 2/2] ata: libata-sata: Fix device queue depth control

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

The function __ata_change_queue_depth() uses the helper
ata_scsi_find_dev() to get the ata_device structure of a scsi device and
set that device maximum queue depth. However, when the ata device is
managed by libsas, ata_scsi_find_dev() returns NULL, turning
__ata_change_queue_depth() into a nop, which prevents the user from
setting the maximum queue depth of ATA devices used with libsas based
HBAs.

Fix this by renaming __ata_change_queue_depth() to
ata_change_queue_depth() and adding a pointer to the ata_device
structure of the target device as argument. This pointer is provided by
ata_scsi_change_queue_depth() using ata_scsi_find_dev() in the case of
a libata managed device and by sas_change_queue_depth() using
sas_to_ata_dev() in the case of a libsas managed ata device.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
---
 drivers/ata/libata-sata.c           | 24 ++++++++++++------------
 drivers/scsi/libsas/sas_scsi_host.c |  3 ++-
 include/linux/libata.h              |  4 ++--
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
index 7a5fe41aa5ae..13b9d0fdd42c 100644
--- a/drivers/ata/libata-sata.c
+++ b/drivers/ata/libata-sata.c
@@ -1018,26 +1018,25 @@ DEVICE_ATTR(sw_activity, S_IWUSR | S_IRUGO, ata_scsi_activity_show,
 EXPORT_SYMBOL_GPL(dev_attr_sw_activity);
 
 /**
- *	__ata_change_queue_depth - helper for ata_scsi_change_queue_depth
- *	@ap: ATA port to which the device change the queue depth
+ *	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
  *
- *	libsas and libata have different approaches for associating a sdev to
- *	its ata_port.
+ *	Helper to set a device maximum queue depth, usable with both libsas
+ *	and libata.
  *
  */
-int __ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
-			     int queue_depth)
+int ata_change_queue_depth(struct ata_port *ap, struct ata_device *dev,
+			   struct scsi_device *sdev, int queue_depth)
 {
-	struct ata_device *dev;
 	unsigned long flags;
 
-	if (queue_depth < 1 || queue_depth == sdev->queue_depth)
+	if (!dev || !ata_dev_enabled(dev))
 		return sdev->queue_depth;
 
-	dev = ata_scsi_find_dev(ap, sdev);
-	if (!dev || !ata_dev_enabled(dev))
+	if (queue_depth < 1 || queue_depth == sdev->queue_depth)
 		return sdev->queue_depth;
 
 	/* NCQ enabled? */
@@ -1059,7 +1058,7 @@ int __ata_change_queue_depth(struct ata_port *ap, struct scsi_device *sdev,
 
 	return scsi_change_queue_depth(sdev, queue_depth);
 }
-EXPORT_SYMBOL_GPL(__ata_change_queue_depth);
+EXPORT_SYMBOL_GPL(ata_change_queue_depth);
 
 /**
  *	ata_scsi_change_queue_depth - SCSI callback for queue depth config
@@ -1080,7 +1079,8 @@ int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
 {
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
 
-	return __ata_change_queue_depth(ap, sdev, queue_depth);
+	return ata_change_queue_depth(ap, ata_scsi_find_dev(ap, sdev),
+				      sdev, queue_depth);
 }
 EXPORT_SYMBOL_GPL(ata_scsi_change_queue_depth);
 
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 9c82e5dc4fcc..a36fa1c128a8 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -872,7 +872,8 @@ int sas_change_queue_depth(struct scsi_device *sdev, int depth)
 	struct domain_device *dev = sdev_to_domain_dev(sdev);
 
 	if (dev_is_sata(dev))
-		return __ata_change_queue_depth(dev->sata_dev.ap, sdev, depth);
+		return ata_change_queue_depth(dev->sata_dev.ap,
+					      sas_to_ata_dev(dev), sdev, depth);
 
 	if (!sdev->tagged_supported)
 		depth = 1;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 698032e5ef2d..20765d1c5f80 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1136,8 +1136,8 @@ extern int ata_scsi_slave_config(struct scsi_device *sdev);
 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 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 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);
-- 
2.37.3