linux-kernel - [PATCH 3/4] ublk: factor out ublk_get

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Message-Id: <20250421-ublk_constify-v1-3-3371f9e9f73c@purestorage.com>
Date: Mon, 21 Apr 2025 17:46:42 -0600
From: Uday Shankar <ushankar@...estorage.com>
To: Ming Lei <ming.lei@...hat.com>, Jens Axboe <axboe@...nel.dk>
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Uday Shankar <ushankar@...estorage.com>, 
 Caleb Sander Mateos <csander@...estorage.com>
Subject: [PATCH 3/4] ublk: factor out ublk_get_data

Move all the logic for the UBLK_IO_NEED_GET_DATA opcode into its own
function. This also allows us to mark ublk_queue pointers as const for
that operation, which can help prevent data races since we may allow
concurrent operation on one ublk_queue in the future.

Suggested-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Uday Shankar <ushankar@...estorage.com>
Reviewed-by: Caleb Sander Mateos <csander@...estorage.com>
---
 drivers/block/ublk_drv.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index a617ffde412936d3c37a3ded08a79e3557f4f56f..f5d4593d5941931efa7bc7d2106830cd2981f4bd 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1241,7 +1241,7 @@ static void ublk_cmd_tw_cb(struct io_uring_cmd *cmd,
 	ublk_dispatch_req(ubq, pdu->req, issue_flags);
 }
 
-static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)
+static void ublk_queue_cmd(const struct ublk_queue *ubq, struct request *rq)
 {
 	struct io_uring_cmd *cmd = ubq->ios[rq->tag].cmd;
 	struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
@@ -1864,15 +1864,6 @@ static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
 	}
 }
 
-static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
-		int tag)
-{
-	struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
-	struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
-
-	ublk_queue_cmd(ubq, req);
-}
-
 static inline int ublk_check_cmd_op(u32 cmd_op)
 {
 	u32 ioc_type = _IOC_TYPE(cmd_op);
@@ -2032,6 +2023,22 @@ static int ublk_commit_and_fetch(const struct ublk_queue *ubq,
 	return 0;
 }
 
+static int ublk_get_data(const struct ublk_queue *ubq, struct ublk_io *io,
+			 struct io_uring_cmd *cmd,
+			 const struct ublksrv_io_cmd *ub_cmd)
+{
+	struct blk_mq_tags *tags = ubq->dev->tag_set.tags[ub_cmd->q_id];
+	struct request *req = blk_mq_tag_to_rq(tags, ub_cmd->tag);
+
+	if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
+		return -EINVAL;
+
+	ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
+	ublk_queue_cmd(ubq, req);
+
+	return 0;
+}
+
 static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
 			       unsigned int issue_flags,
 			       const struct ublksrv_io_cmd *ub_cmd)
@@ -2097,10 +2104,9 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
 			goto out;
 		break;
 	case UBLK_IO_NEED_GET_DATA:
-		if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
+		ret = ublk_get_data(ubq, io, cmd, ub_cmd);
+		if (ret)
 			goto out;
-		ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
-		ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag);
 		break;
 	default:
 		goto out;

-- 
2.34.1