Add helper __ublk_fetch() for the coming batch io feature.

Meantime move ublk_config_io_buf() out of __ublk_fetch() because batch
io has new interface for configuring buffer.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/block/ublk_drv.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index e53f623b0efe..f265795a8d57 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -2206,18 +2206,12 @@ static int ublk_check_fetch_buf(const struct ublk_queue *ubq, __u64 buf_addr)
 	return 0;
 }
 
-static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
-		      struct ublk_io *io, __u64 buf_addr)
+static int __ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
+			struct ublk_io *io)
 {
 	struct ublk_device *ub = ubq->dev;
 	int ret = 0;
 
-	/*
-	 * When handling FETCH command for setting up ublk uring queue,
-	 * ub->mutex is the innermost lock, and we won't block for handling
-	 * FETCH, so it is fine even for IO_URING_F_NONBLOCK.
-	 */
-	mutex_lock(&ub->mutex);
 	/* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
 	if (ublk_queue_ready(ubq)) {
 		ret = -EBUSY;
@@ -2233,13 +2227,28 @@ static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
 	WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV);
 
 	ublk_fill_io_cmd(io, cmd);
-	ret = ublk_config_io_buf(ubq, io, cmd, buf_addr, NULL);
-	if (ret)
-		goto out;
 
 	WRITE_ONCE(io->task, get_task_struct(current));
 	ublk_mark_io_ready(ub, ubq);
 out:
+	return ret;
+}
+
+static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_queue *ubq,
+		      struct ublk_io *io, __u64 buf_addr)
+{
+	struct ublk_device *ub = ubq->dev;
+	int ret;
+
+	/*
+	 * When handling FETCH command for setting up ublk uring queue,
+	 * ub->mutex is the innermost lock, and we won't block for handling
+	 * FETCH, so it is fine even for IO_URING_F_NONBLOCK.
+	 */
+	mutex_lock(&ub->mutex);
+	ret = ublk_config_io_buf(ubq, io, cmd, buf_addr, NULL);
+	if (!ret)
+		ret = __ublk_fetch(cmd, ubq, io);
 	mutex_unlock(&ub->mutex);
 	return ret;
 }
-- 
2.47.0