[PATCH v2 13/14] ublk: remove ubq checks from ublk_{get,put}_req_ref()

[Caleb Sander Mateos <csander@purestorage.com>]

ublk_get_req_ref() and ublk_put_req_ref() currently call
ublk_need_req_ref(ubq) to check whether the ublk device features require
reference counting of its requests. However, all callers already know
that reference counting is required:
- __ublk_check_and_get_req() is only called from
  ublk_check_and_get_req() if user copy is enabled, and from
  ublk_register_io_buf() if zero copy is enabled
- ublk_io_release() is only called for requests registered by
  ublk_register_io_buf(), which requires zero copy
- ublk_ch_read_iter() and ublk_ch_write_iter() only call
  ublk_put_req_ref() if ublk_check_and_get_req() succeeded, which
  requires user copy to be enabled

So drop the ublk_need_req_ref() check and the ubq argument in
ublk_get_req_ref() and ublk_put_req_ref().

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
---
 drivers/block/ublk_drv.c | 35 +++++++++++------------------------
 1 file changed, 11 insertions(+), 24 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 199028f36ec8..ebc56681eb68 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -697,28 +697,19 @@ static inline void ublk_init_req_ref(const struct ublk_queue *ubq,
 {
 	if (ublk_need_req_ref(ubq))
 		refcount_set(&io->ref, UBLK_REFCOUNT_INIT);
 }
 
-static inline bool ublk_get_req_ref(const struct ublk_queue *ubq,
-		struct ublk_io *io)
+static inline bool ublk_get_req_ref(struct ublk_io *io)
 {
-	if (ublk_need_req_ref(ubq))
-		return refcount_inc_not_zero(&io->ref);
-
-	return true;
+	return refcount_inc_not_zero(&io->ref);
 }
 
-static inline void ublk_put_req_ref(const struct ublk_queue *ubq,
-		struct ublk_io *io, struct request *req)
+static inline void ublk_put_req_ref(struct ublk_io *io, struct request *req)
 {
-	if (ublk_need_req_ref(ubq)) {
-		if (refcount_dec_and_test(&io->ref))
-			__ublk_complete_rq(req);
-	} else {
+	if (refcount_dec_and_test(&io->ref))
 		__ublk_complete_rq(req);
-	}
 }
 
 static inline void ublk_sub_req_ref(struct ublk_io *io, struct request *req)
 {
 	unsigned sub_refs = UBLK_REFCOUNT_INIT - io->task_registered_buffers;
@@ -2019,11 +2010,11 @@ static void ublk_io_release(void *priv)
 	 * but unregistered on task. Or after UBLK_IO_COMMIT_AND_FETCH_REQ.
 	 */
 	if (current == io->task && io->task_registered_buffers)
 		io->task_registered_buffers--;
 	else
-		ublk_put_req_ref(ubq, io, rq);
+		ublk_put_req_ref(io, rq);
 }
 
 static int ublk_register_io_buf(struct io_uring_cmd *cmd,
 				const struct ublk_queue *ubq,
 				struct ublk_io *io,
@@ -2041,11 +2032,11 @@ static int ublk_register_io_buf(struct io_uring_cmd *cmd,
 		return -EINVAL;
 
 	ret = io_buffer_register_bvec(cmd, req, ublk_io_release, index,
 				      issue_flags);
 	if (ret) {
-		ublk_put_req_ref(ubq, io, req);
+		ublk_put_req_ref(io, req);
 		return ret;
 	}
 
 	return 0;
 }
@@ -2338,11 +2329,11 @@ static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
 	 */
 	req = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], tag);
 	if (!req)
 		return NULL;
 
-	if (!ublk_get_req_ref(ubq, io))
+	if (!ublk_get_req_ref(io))
 		return NULL;
 
 	if (unlikely(!blk_mq_request_started(req) || req->tag != tag))
 		goto fail_put;
 
@@ -2352,11 +2343,11 @@ static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
 	if (offset > blk_rq_bytes(req))
 		goto fail_put;
 
 	return req;
 fail_put:
-	ublk_put_req_ref(ubq, io, req);
+	ublk_put_req_ref(io, req);
 	return NULL;
 }
 
 static inline int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd,
 		unsigned int issue_flags)
@@ -2468,48 +2459,44 @@ static struct request *ublk_check_and_get_req(struct kiocb *iocb,
 		goto fail;
 
 	*off = buf_off;
 	return req;
 fail:
-	ublk_put_req_ref(ubq, *io, req);
+	ublk_put_req_ref(*io, req);
 	return ERR_PTR(-EACCES);
 }
 
 static ssize_t ublk_ch_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-	struct ublk_queue *ubq;
 	struct request *req;
 	struct ublk_io *io;
 	size_t buf_off;
 	size_t ret;
 
 	req = ublk_check_and_get_req(iocb, to, &buf_off, ITER_DEST, &io);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
 	ret = ublk_copy_user_pages(req, buf_off, to, ITER_DEST);
-	ubq = req->mq_hctx->driver_data;
-	ublk_put_req_ref(ubq, io, req);
+	ublk_put_req_ref(io, req);
 
 	return ret;
 }
 
 static ssize_t ublk_ch_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-	struct ublk_queue *ubq;
 	struct request *req;
 	struct ublk_io *io;
 	size_t buf_off;
 	size_t ret;
 
 	req = ublk_check_and_get_req(iocb, from, &buf_off, ITER_SOURCE, &io);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
 	ret = ublk_copy_user_pages(req, buf_off, from, ITER_SOURCE);
-	ubq = req->mq_hctx->driver_data;
-	ublk_put_req_ref(ubq, io, req);
+	ublk_put_req_ref(io, req);
 
 	return ret;
 }
 
 static const struct file_operations ublk_ch_fops = {
-- 
2.45.2