scsi: Use blk_rq_map_user_io helper

Use the new blk_rq_map_user_io helper instead of duplicating code at
various places. Additionally this also takes advantage of the on-stack
iov fast path.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220930062749.152261-5-anuj20.g@samsung.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/scsi/scsi_ioctl.c

@@ -449,25 +449,9 @@ static int sg_io(struct scsi_device *sdev, struct sg_io_hdr *hdr, fmode_t mode)
 	if (ret < 0)
 		goto out_put_request;
 
-	ret = 0;
-	if (hdr->iovec_count && hdr->dxfer_len) {
-		struct iov_iter i;
-		struct iovec *iov = NULL;
-
-		ret = import_iovec(rq_data_dir(rq), hdr->dxferp,
-				   hdr->iovec_count, 0, &iov, &i);
-		if (ret < 0)
-			goto out_put_request;
-
-		/* SG_IO howto says that the shorter of the two wins */
-		iov_iter_truncate(&i, hdr->dxfer_len);
-
-		ret = blk_rq_map_user_iov(rq->q, rq, NULL, &i, GFP_KERNEL);
-		kfree(iov);
-	} else if (hdr->dxfer_len)
-		ret = blk_rq_map_user(rq->q, rq, NULL, hdr->dxferp,
-				      hdr->dxfer_len, GFP_KERNEL);
-
+	ret = blk_rq_map_user_io(rq, NULL, hdr->dxferp, hdr->dxfer_len,
+			GFP_KERNEL, hdr->iovec_count && hdr->dxfer_len,
+			hdr->iovec_count, 0, rq_data_dir(rq));
 	if (ret)
 		goto out_put_request;
 

drivers/scsi/sg.c

@@ -1804,26 +1804,8 @@ sg_start_req(Sg_request *srp, unsigned char *cmd)
 			md->from_user = 0;
 	}
 
-	if (iov_count) {
-		struct iovec *iov = NULL;
-		struct iov_iter i;
-
-		res = import_iovec(rw, hp->dxferp, iov_count, 0, &iov, &i);
-		if (res < 0)
-			return res;
-
-		iov_iter_truncate(&i, hp->dxfer_len);
-		if (!iov_iter_count(&i)) {
-			kfree(iov);
-			return -EINVAL;
-		}
-
-		res = blk_rq_map_user_iov(q, rq, md, &i, GFP_ATOMIC);
-		kfree(iov);
-	} else
-		res = blk_rq_map_user(q, rq, md, hp->dxferp,
-				      hp->dxfer_len, GFP_ATOMIC);
-
+	res = blk_rq_map_user_io(rq, md, hp->dxferp, hp->dxfer_len,
+			GFP_ATOMIC, iov_count, iov_count, 1, rw);
 	if (!res) {
 		srp->bio = rq->bio;