[PATCH 2/5] block: make blk_rq_map_kern() to accept a NULL buffer

[Hannes Reinecke <hare@suse.de>]

We really should accept a NULL buffer as argument, avoiding conditional
coding in the caller.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-map.c           |  2 +-
 drivers/block/pktcdvd.c   | 10 ++++------
 drivers/nvme/host/core.c  |  8 +++-----
 drivers/scsi/scsi_ioctl.c |  8 +++-----
 drivers/scsi/scsi_lib.c   | 11 +++++------
 5 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index 859590be077e..4615386b85d3 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -783,7 +783,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	if (len > (queue_max_hw_sectors(q) << 9))
 		return -EINVAL;
 	if (!len || !kbuf)
-		return -EINVAL;
+		return 0;
 
 	if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
 	    blk_queue_may_bounce(q))
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 2f1a92509271..9e49cca82bfd 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -694,12 +694,10 @@ static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *
 		return PTR_ERR(rq);
 	scmd = blk_mq_rq_to_pdu(rq);
 
-	if (cgc->buflen) {
-		ret = blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen,
-				      GFP_NOIO);
-		if (ret)
-			goto out;
-	}
+	ret = blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen,
+			      GFP_NOIO);
+	if (ret)
+		goto out;
 
 	scmd->cmd_len = COMMAND_SIZE(cgc->cmd[0]);
 	memcpy(scmd->cmnd, cgc->cmd, CDROM_PACKET_SIZE);
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ad2bcb412944..78da9c6cbba8 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1044,11 +1044,9 @@ int __nvme_submit_sync_cmd(struct request *req, union nvme_result *result,
 {
 	int ret;
 
-	if (buffer && bufflen) {
-		ret = blk_rq_map_kern(req->q, req, buffer, bufflen, GFP_KERNEL);
-		if (ret)
-			goto out;
-	}
+	ret = blk_rq_map_kern(req->q, req, buffer, bufflen, GFP_KERNEL);
+	if (ret)
+		goto out;
 
 	ret = nvme_execute_rq(req, at_head);
 	if (result && ret >= 0)
diff --git a/drivers/scsi/scsi_ioctl.c b/drivers/scsi/scsi_ioctl.c
index 1126a265d5ee..1e182d71ce74 100644
--- a/drivers/scsi/scsi_ioctl.c
+++ b/drivers/scsi/scsi_ioctl.c
@@ -581,11 +581,9 @@ static int sg_scsi_ioctl(struct request_queue *q, fmode_t mode,
 		break;
 	}
 
-	if (bytes) {
-		err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO);
-		if (err)
-			goto error;
-	}
+	err = blk_rq_map_kern(q, rq, buffer, bytes, GFP_NOIO);
+	if (err)
+		goto error;
 
 	blk_execute_rq(rq, false);
 
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 9ed1ebcb7443..b15ddf6820a3 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -221,12 +221,11 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	if (bufflen) {
-		ret = blk_rq_map_kern(sdev->request_queue, req,
-				      buffer, bufflen, GFP_NOIO);
-		if (ret)
-			goto out;
-	}
+	ret = blk_rq_map_kern(sdev->request_queue, req,
+			buffer, bufflen, GFP_NOIO);
+	if (ret)
+		goto out;
+
 	scmd = blk_mq_rq_to_pdu(req);
 	scmd->cmd_len = COMMAND_SIZE(cmd[0]);
 	memcpy(scmd->cmnd, cmd, scmd->cmd_len);
-- 
2.35.3