tree efab6520c3793325ef2881f7fbe2e34df75f2204
parent a57821cac6bb6e46abea118e34d0e86444ec1410
author Tony Battersby <tonyb@cybernetics.com> 1408737219 -0400
committer Jens Axboe <axboe@fb.com> 1408737871 -0500

scsi-mq: fix requests that use a separate CDB buffer

This patch fixes code such as the following with scsi-mq enabled:

    rq = blk_get_request(...);
    blk_rq_set_block_pc(rq);

    rq->cmd = my_cmd_buffer; /* separate CDB buffer */

    blk_execute_rq_nowait(...);

Code like this appears in e.g. sg_start_req() in drivers/scsi/sg.c (for
large CDBs only).  Without this patch, scsi_mq_prep_fn() will set
rq->cmd back to rq->__cmd, causing the wrong CDB to be sent to the device.

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Jens Axboe <axboe@fb.com>