[PATCH 7.2 0/2] ublk: optimize ublk_rq_has_data()

[PATCH 7.2 0/2] ublk: optimize ublk_rq_has_data()

[Caleb Sander Mateos]

ublk_rq_has_data() currently uses bio_has_data(), which involves 2
indirections and several branches. Introduce a blk_rq_has_data()
analogue for struct request and use it instead to save an indirection
and NULL check.

Caleb Sander Mateos (2):
  blk-mq: introduce blk_rq_has_data()
  ublk: optimize ublk_rq_has_data()

 drivers/block/ublk_drv.c | 21 ++++++++-------------
 include/linux/blk-mq.h   |  9 +++++++++
 2 files changed, 17 insertions(+), 13 deletions(-)

-- 
2.54.0

[PATCH 7.2 1/2] blk-mq: introduce blk_rq_has_data()

[Caleb Sander Mateos]

Add blk_rq_has_data(), an analogue of bio_has_data() for struct request.
This skips one dereference relative to bio_has_data(rq->bio).

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 include/linux/blk-mq.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 18a2388ba581..4349aefdbc87 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -1102,10 +1102,11 @@ struct req_iterator {
 		 bio_iter_last(bvec, _iter.iter))
 
 /*
  * blk_rq_pos()			: the current sector
  * blk_rq_bytes()		: bytes left in the entire request
+ * blk_rq_has_data()		: whether the request carries data
  * blk_rq_cur_bytes()		: bytes left in the current segment
  * blk_rq_sectors()		: sectors left in the entire request
  * blk_rq_cur_sectors()		: sectors left in the current segment
  * blk_rq_stats_sectors()	: sectors of the entire request used for stats
  */
@@ -1117,10 +1118,18 @@ static inline sector_t blk_rq_pos(const struct request *rq)
 static inline unsigned int blk_rq_bytes(const struct request *rq)
 {
 	return rq->__data_len;
 }
 
+static inline bool blk_rq_has_data(const struct request *rq)
+{
+	return blk_rq_bytes(rq) &&
+	       req_op(rq) != REQ_OP_DISCARD &&
+	       req_op(rq) != REQ_OP_SECURE_ERASE &&
+	       req_op(rq) != REQ_OP_WRITE_ZEROES;
+}
+
 static inline int blk_rq_cur_bytes(const struct request *rq)
 {
 	if (!rq->bio)
 		return 0;
 	if (!bio_has_data(rq->bio))	/* dataless requests such as discard */
-- 
2.54.0

Re: [PATCH 7.2 1/2] blk-mq: introduce blk_rq_has_data()

[Ming Lei]

On Wed, May 13, 2026 at 03:18:45PM -0600, Caleb Sander Mateos wrote:
> Add blk_rq_has_data(), an analogue of bio_has_data() for struct request.
> This skips one dereference relative to bio_has_data(rq->bio).
> 
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>

Reviewed-by: Ming Lei <tom.leiming@gmail.com>

Thanks,
Ming

[PATCH 7.2 2/2] ublk: optimize ublk_rq_has_data()

[Caleb Sander Mateos]

ublk_rq_has_data() currently uses bio_has_data(), which involves 2
indirections and several branches. Use blk_rq_has_data() instead to save
an indirection and NULL check.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 drivers/block/ublk_drv.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 8e5f3738c203..4d7efc12247c 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1170,15 +1170,10 @@ static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev,
 		int qid)
 {
 	return dev->queues[qid];
 }
 
-static inline bool ublk_rq_has_data(const struct request *rq)
-{
-	return bio_has_data(rq->bio);
-}
-
 static inline struct ublksrv_io_desc *
 ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
 {
 	return ublk_get_queue(ub, q_id)->io_cmd_buf;
 }
@@ -1387,16 +1382,16 @@ static size_t ublk_copy_user_integrity(const struct request *req,
 }
 #endif /* #ifdef CONFIG_BLK_DEV_INTEGRITY */
 
 static inline bool ublk_need_map_req(const struct request *req)
 {
-	return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;
+	return blk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;
 }
 
 static inline bool ublk_need_unmap_req(const struct request *req)
 {
-	return ublk_rq_has_data(req) &&
+	return blk_rq_has_data(req) &&
 	       (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN);
 }
 
 static unsigned int ublk_map_io(const struct ublk_queue *ubq,
 				const struct request *req,
@@ -1506,11 +1501,11 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 	iod->op_flags = ublk_op | ublk_req_build_flags(req);
 	iod->nr_sectors = blk_rq_sectors(req);
 	iod->start_sector = blk_rq_pos(req);
 
 	/* Try shmem zero-copy match before setting addr */
-	if (ublk_support_shmem_zc(ubq) && ublk_rq_has_data(req)) {
+	if (ublk_support_shmem_zc(ubq) && blk_rq_has_data(req)) {
 		u32 buf_idx, buf_off;
 
 		if (ublk_try_buf_match(ubq->dev, req,
 					  &buf_idx, &buf_off)) {
 			iod->op_flags |= UBLK_IO_F_SHMEM_ZC;
@@ -1796,11 +1791,11 @@ static void ublk_dispatch_req(struct ublk_queue *ubq, struct request *req)
 	}
 
 	if (!ublk_start_io(ubq, req, io))
 		return;
 
-	if (ublk_support_auto_buf_reg(ubq) && ublk_rq_has_data(req)) {
+	if (ublk_support_auto_buf_reg(ubq) && blk_rq_has_data(req)) {
 		ublk_auto_buf_dispatch(ubq, req, io, io->cmd, issue_flags);
 	} else {
 		ublk_init_req_ref(ubq, io);
 		ublk_complete_io_cmd(io, req, UBLK_IO_RES_OK, issue_flags);
 	}
@@ -1817,11 +1812,11 @@ static bool __ublk_batch_prep_dispatch(struct ublk_queue *ubq,
 	struct io_uring_cmd *cmd = data->cmd;
 
 	if (!ublk_start_io(ubq, req, io))
 		return false;
 
-	if (ublk_support_auto_buf_reg(ubq) && ublk_rq_has_data(req)) {
+	if (ublk_support_auto_buf_reg(ubq) && blk_rq_has_data(req)) {
 		res = ublk_auto_buf_register(ubq, req, io, cmd,
 				data->issue_flags);
 
 		if (res == AUTO_BUF_REG_FAIL)
 			return false;
@@ -3198,11 +3193,11 @@ ublk_daemon_register_io_buf(struct io_uring_cmd *cmd,
 	new_registered_buffers = io->task_registered_buffers + 1;
 	if (unlikely(new_registered_buffers >= UBLK_REFCOUNT_INIT))
 		return ublk_register_io_buf(cmd, ub, q_id, tag, io, index,
 					    issue_flags);
 
-	if (!ublk_dev_support_zero_copy(ub) || !ublk_rq_has_data(req))
+	if (!ublk_dev_support_zero_copy(ub) || !blk_rq_has_data(req))
 		return -EINVAL;
 
 	ret = io_buffer_register_bvec(cmd, req, ublk_io_release, index,
 				      issue_flags);
 	if (ret)
@@ -3481,11 +3476,11 @@ static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
 		return NULL;
 
 	if (unlikely(!blk_mq_request_started(req) || req->tag != tag))
 		goto fail_put;
 
-	if (!ublk_rq_has_data(req))
+	if (!blk_rq_has_data(req))
 		goto fail_put;
 
 	return req;
 fail_put:
 	ublk_put_req_ref(io, req);
@@ -4054,11 +4049,11 @@ ublk_user_copy(struct kiocb *iocb, struct iov_iter *iter, int dir)
 		/* On daemon, io can't be completed concurrently, so skip ref */
 		if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
 			return -EINVAL;
 
 		req = io->req;
-		if (!ublk_rq_has_data(req))
+		if (!blk_rq_has_data(req))
 			return -EINVAL;
 	} else {
 		req = __ublk_check_and_get_req(ub, q_id, tag, io);
 		if (!req)
 			return -EINVAL;
-- 
2.54.0

Re: [PATCH 7.2 2/2] ublk: optimize ublk_rq_has_data()

[Ming Lei]

On Wed, May 13, 2026 at 03:18:46PM -0600, Caleb Sander Mateos wrote:
> ublk_rq_has_data() currently uses bio_has_data(), which involves 2
> indirections and several branches. Use blk_rq_has_data() instead to save
> an indirection and NULL check.
> 
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>

Reviewed-by: Ming Lei <tom.leiming@gmail.com>


Thanks,
Ming