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bsg: split handling of SCSI CDBs vs transport requeues

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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>
This commit is contained in:
Christoph Hellwig
2018-03-13 17:28:41 +01:00
committed by Jens Axboe
parent ef6fa64f9b
commit 17cb960f29
7 changed files with 268 additions and 235 deletions
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4
drivers/scsi/scsi_lib.c
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@@ -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;
}