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, 13 insertions, 11 deletions

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index f925b1f1f9ad..3adba389cae5 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -966,6 +966,7 @@ static int sr_read_cdda_bpc(struct cdrom_device_info *cdi, void __user *ubuf,
 	struct gendisk *disk = cdi->disk;
 	u32 len = nr * CD_FRAMESIZE_RAW;
 	struct scsi_request *req;
+	struct scsi_cmnd *scmd;
 	struct request *rq;
 	struct bio *bio;
 	int ret;
@@ -974,22 +975,23 @@ static int sr_read_cdda_bpc(struct cdrom_device_info *cdi, void __user *ubuf,
 	if (IS_ERR(rq))
 		return PTR_ERR(rq);
 	req = scsi_req(rq);
+	scmd = blk_mq_rq_to_pdu(rq);
 
 	ret = blk_rq_map_user(disk->queue, rq, NULL, ubuf, len, GFP_KERNEL);
 	if (ret)
 		goto out_put_request;
 
-	req->cmd[0] = GPCMD_READ_CD;
-	req->cmd[1] = 1 << 2;
-	req->cmd[2] = (lba >> 24) & 0xff;
-	req->cmd[3] = (lba >> 16) & 0xff;
-	req->cmd[4] = (lba >>  8) & 0xff;
-	req->cmd[5] = lba & 0xff;
-	req->cmd[6] = (nr >> 16) & 0xff;
-	req->cmd[7] = (nr >>  8) & 0xff;
-	req->cmd[8] = nr & 0xff;
-	req->cmd[9] = 0xf8;
-	req->cmd_len = 12;
+	scmd->cmnd[0] = GPCMD_READ_CD;
+	scmd->cmnd[1] = 1 << 2;
+	scmd->cmnd[2] = (lba >> 24) & 0xff;
+	scmd->cmnd[3] = (lba >> 16) & 0xff;
+	scmd->cmnd[4] = (lba >>  8) & 0xff;
+	scmd->cmnd[5] = lba & 0xff;
+	scmd->cmnd[6] = (nr >> 16) & 0xff;
+	scmd->cmnd[7] = (nr >>  8) & 0xff;
+	scmd->cmnd[8] = nr & 0xff;
+	scmd->cmnd[9] = 0xf8;
+	scmd->cmd_len = 12;
 	rq->timeout = 60 * HZ;
 	bio = rq->bio;