scsi: core: Remove the cmd field from struct scsi_request

Now that each scsi_request is backed by a scsi_cmnd, there is no need to
indirect the CDB storage.  Change all submitters of SCSI passthrough
requests to store the CDB information directly in the scsi_cmnd, and while
doing so allocate the full 32 bytes that cover all Linux supported SCSI
hosts instead of requiring dynamic allocation for > 16 byte CDBs.  On
64-bit systems this does not change the size of the scsi_cmnd at all, while
on 32-bit systems it slightly increases it for now, but that increase will
be made up by the removal of the remaining scsi_request fields.

Link: https://lore.kernel.org/r/20220224175552.988286-4-hch@lst.de
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index ed8be585a98f..c8283bd4ffd1 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1022,7 +1022,9 @@ void ata_scsi_sdev_config(struct scsi_device *sdev)
  */
 bool ata_scsi_dma_need_drain(struct request *rq)
 {
-	return atapi_cmd_type(scsi_req(rq)->cmd[0]) == ATAPI_MISC;
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
+
+	return atapi_cmd_type(scmd->cmnd[0]) == ATAPI_MISC;
 }
 EXPORT_SYMBOL_GPL(ata_scsi_dma_need_drain);