bsg: split handling of SCSI CDBs vs transport requeues

The current BSG design tries to shoe-horn the transport-specific
passthrough commands into the overall framework for SCSI passthrough
requests.  This has a couple problems:

 - each passthrough queue has to set the QUEUE_FLAG_SCSI_PASSTHROUGH flag
   despite not dealing with SCSI commands at all.  Because of that these
   queues could also incorrectly accept SCSI commands from in-kernel
   users or through the legacy SCSI_IOCTL_SEND_COMMAND ioctl.
 - the real SCSI bsg queues also incorrectly accept bsg requests of the
   BSG_SUB_PROTOCOL_SCSI_TRANSPORT type
 - the bsg transport code is almost unredable because it tries to reuse
   different SCSI concepts for its own purpose.

This patch instead adds a new bsg_ops structure to handle the two cases
differently, and thus solves all of the above problems.  Another side
effect is that the bsg-lib queues also don't need to embedd a
struct scsi_request anymore.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 538152f..37c1d63 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2140,8 +2140,6 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
 {
 	struct device *dev = shost->dma_dev;
 
-	blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, q);
-
 	/*
 	 * this limit is imposed by hardware restrictions
 	 */
@@ -2239,6 +2237,7 @@ struct request_queue *scsi_old_alloc_queue(struct scsi_device *sdev)
 	}
 
 	__scsi_init_queue(shost, q);
+	blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, q);
 	blk_queue_prep_rq(q, scsi_prep_fn);
 	blk_queue_unprep_rq(q, scsi_unprep_fn);
 	blk_queue_softirq_done(q, scsi_softirq_done);
@@ -2270,6 +2269,7 @@ struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
 
 	sdev->request_queue->queuedata = sdev;
 	__scsi_init_queue(sdev->host, sdev->request_queue);
+	blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, sdev->request_queue);
 	return sdev->request_queue;
 }
 
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 91b90f6..7142c8b 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1292,8 +1292,7 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 	transport_add_device(&sdev->sdev_gendev);
 	sdev->is_visible = 1;
 
-	error = bsg_register_queue(rq, &sdev->sdev_gendev, NULL, NULL);
-
+	error = bsg_scsi_register_queue(rq, &sdev->sdev_gendev);
 	if (error)
 		/* we're treating error on bsg register as non-fatal,
 		 * so pretend nothing went wrong */
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index 7c09876..08acbab 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -228,7 +228,6 @@ static int sas_bsg_initialize(struct Scsi_Host *shost, struct sas_rphy *rphy)
 	 */
 	blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
 	blk_queue_flag_set(QUEUE_FLAG_BIDI, q);
-	blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, q);
 	return 0;
 }