[RFC PATCH 11/13] scsi: Allow device handler set their own CDB

[Avri Altman <avri.altman@wdc.com>]

Allow scsi device handler handle their own CDB and ship it down the
stream of scsi passthrough command setup flow, without any further
interventions.

This is useful for setting DRV-OP that implements vendor commands via
the scsi device handlers framework.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/scsi_lib.c | 5 +++--
 drivers/scsi/sd.c       | 9 +++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 6b6dd40..4e98714 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1148,14 +1148,15 @@ static blk_status_t scsi_setup_fs_cmnd(struct scsi_device *sdev,
 {
 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
 
+	cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd;
+	memset(cmd->cmnd, 0, BLK_MAX_CDB);
+
 	if (unlikely(sdev->handler && sdev->handler->prep_fn)) {
 		blk_status_t ret = sdev->handler->prep_fn(sdev, req);
 		if (ret != BLK_STS_OK)
 			return ret;
 	}
 
-	cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd;
-	memset(cmd->cmnd, 0, BLK_MAX_CDB);
 	return scsi_cmd_to_driver(cmd)->init_command(cmd);
 }
 
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a793cb0..246bef8 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1221,6 +1221,14 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
 	} else if (sdp->use_16_for_rw || (nr_blocks > 0xffff)) {
 		ret = sd_setup_rw16_cmnd(cmd, write, lba, nr_blocks,
 					 protect | fua);
+	} else if (unlikely(sdp->handler && blk_rq_is_private(rq))) {
+		/*
+		 * scsi device handler that implements vendor commands -
+		 * the command was already constructed in the device handler's
+		 * prep_fn, so no need to do anything here
+		 */
+		rq->cmd_flags = REQ_OP_READ;
+		ret = BLK_STS_OK;
 	} else if ((nr_blocks > 0xff) || (lba > 0x1fffff) ||
 		   sdp->use_10_for_rw || protect) {
 		ret = sd_setup_rw10_cmnd(cmd, write, lba, nr_blocks,
@@ -1285,6 +1293,7 @@ static blk_status_t sd_init_command(struct scsi_cmnd *cmd)
 		return sd_setup_write_same_cmnd(cmd);
 	case REQ_OP_FLUSH:
 		return sd_setup_flush_cmnd(cmd);
+	case REQ_OP_DRV_IN:
 	case REQ_OP_READ:
 	case REQ_OP_WRITE:
 		return sd_setup_read_write_cmnd(cmd);
-- 
2.7.4