scsi: don't set tagging state from scsi_adjust_queue_depth

Remove the tagged argument from scsi_adjust_queue_depth, and just let it
handle the queue depth.  For most drivers those two are fairly separate,
given that most modern drivers don't care about the SCSI "tagged" status
of a command at all, and many old drivers allow queuing of multiple
untagged commands in the driver.

Instead we start out with the ->simple_tags flag set before calling
->slave_configure, which is how all drivers actually looking at
->simple_tags except for one worke anyway.  The one other case looks
broken, but I've kept the behavior as-is for now.

Except for that we only change ->simple_tags from the ->change_queue_type,
and when rejecting a tag message in a single driver, so keeping this
churn out of scsi_adjust_queue_depth is a clear win.

Now that the usage of scsi_adjust_queue_depth is more obvious we can
also remove all the trivial instances in ->slave_alloc or ->slave_configure
that just set it to the cmd_per_lun default.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_scan.c

@@ -292,7 +292,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
 		blk_queue_init_tags(sdev->request_queue,
 				    sdev->host->cmd_per_lun, shost->bqt);
 	}
-	scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
+	scsi_adjust_queue_depth(sdev, sdev->host->cmd_per_lun);
 
 	scsi_sysfs_device_initialize(sdev);
 
@@ -880,8 +880,10 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
 			(inq_result[3] & 0x0f) == 1 ? " CCS" : "");
 
 	if ((sdev->scsi_level >= SCSI_2) && (inq_result[7] & 2) &&
-	    !(*bflags & BLIST_NOTQ))
+	    !(*bflags & BLIST_NOTQ)) {
 		sdev->tagged_supported = 1;
+		sdev->simple_tags = 1;
+	}
 
 	/*
 	 * Some devices (Texel CD ROM drives) have handshaking problems