scsi: use host wide tags by default

This patch changes the !blk-mq path to the same defaults as the blk-mq
I/O path by always enabling block tagging, and always using host wide
tags.  We've had blk-mq available for a few releases so bugs with
this mode should have been ironed out, and this ensures we get better
coverage of over tagging setup over different configs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

1 files changed, 3 insertions, 24 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 207d6a7..d07fb65 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -616,32 +616,11 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
  */
 int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
 {
-	unsigned long flags;
-
-	if (depth <= 0)
-		goto out;
-
-	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
-
-	/*
-	 * Check to see if the queue is managed by the block layer.
-	 * If it is, and we fail to adjust the depth, exit.
-	 *
-	 * Do not resize the tag map if it is a host wide share bqt,
-	 * because the size should be the hosts's can_queue. If there
-	 * is more IO than the LLD's can_queue (so there are not enuogh
-	 * tags) request_fn's host queue ready check will handle it.
-	 */
-	if (!shost_use_blk_mq(sdev->host) && !sdev->host->bqt) {
-		if (blk_queue_tagged(sdev->request_queue) &&
-		    blk_queue_resize_tags(sdev->request_queue, depth) != 0)
-			goto out_unlock;
+	if (depth > 0) {
+		sdev->queue_depth = depth;
+		wmb();
 	}
 
-	sdev->queue_depth = depth;
-out_unlock:
-	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
-out:
 	return sdev->queue_depth;
 }
 EXPORT_SYMBOL(scsi_change_queue_depth);