libata: fix ata_scsi_change_queue_depth()

Fix ata_scsi_change_queue_depth() such that...

* NCQ on/off is exactly determined using the same logic as the issue path.

* queue depth is adjusted to 1 if NCQ is not enabled.

* -EINVAL is returned if requested action is ignored due to limitations.

This fixes the bug which allows queue depth to be increased on
blacklisted NCQ hosts/devices.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index aa6cb6dcec4169a3df98f9f0baa2e8e6ccdc8528..48e388800f5ab5ab54c7b6e0e095e1e529c774e0 100644 (file)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -987,29 +987,32 @@ int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
        struct ata_port *ap = ata_shost_to_port(sdev->host);
        struct ata_device *dev;
        unsigned long flags;
-       int max_depth;
 
-       if (queue_depth < 1)
+       if (queue_depth < 1 || queue_depth == sdev->queue_depth)
                return sdev->queue_depth;
 
        dev = ata_scsi_find_dev(ap, sdev);
        if (!dev || !ata_dev_enabled(dev))
                return sdev->queue_depth;
 
-       max_depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
-       max_depth = min(ATA_MAX_QUEUE - 1, max_depth);
-       if (queue_depth > max_depth)
-               queue_depth = max_depth;
-
-       scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, queue_depth);
-
+       /* NCQ enabled? */
        spin_lock_irqsave(ap->lock, flags);
-       if (queue_depth > 1)
-               dev->flags &= ~ATA_DFLAG_NCQ_OFF;
-       else
+       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 */
+       queue_depth = min(queue_depth, sdev->host->can_queue);
+       queue_depth = min(queue_depth, ata_id_queue_depth(dev->id));
+       queue_depth = min(queue_depth, ATA_MAX_QUEUE - 1);
+
+       if (sdev->queue_depth == queue_depth)
+               return -EINVAL;
+
+       scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, queue_depth);
        return queue_depth;
 }