ublk: add helper of __ublk_fetch()

Add helper __ublk_fetch() for refactoring ublk_fetch().

Meantime move ublk_config_io_buf() out of __ublk_fetch() to make
the code structure cleaner.

Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Ming Lei

drivers/block/ublk_drv.c

@@ -2234,39 +2234,41 @@ static int ublk_check_fetch_buf(const struct ublk_device *ub, __u64 buf_addr)
 	return 0;
 }
 
-static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_device *ub,
-		      struct ublk_io *io, __u64 buf_addr)
+static int __ublk_fetch(struct io_uring_cmd *cmd, struct ublk_device *ub,
+			struct ublk_io *io)
 {
-	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 dev is setup */
-	if (ublk_dev_ready(ub)) {
-		ret = -EBUSY;
-		goto out;
-	}
+	if (ublk_dev_ready(ub))
+		return -EBUSY;
 
 	/* allow each command to be FETCHed at most once */
-	if (io->flags & UBLK_IO_FLAG_ACTIVE) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (io->flags & UBLK_IO_FLAG_ACTIVE)
+		return -EINVAL;
 
 	WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV);
 
 	ublk_fill_io_cmd(io, cmd);
-	ret = ublk_config_io_buf(ub, io, cmd, buf_addr, NULL);
-	if (ret)
-		goto out;
 
 	WRITE_ONCE(io->task, get_task_struct(current));
 	ublk_mark_io_ready(ub);
-out:
+
+	return 0;
+}
+
+static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_device *ub,
+		      struct ublk_io *io, __u64 buf_addr)
+{
+	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_fetch(cmd, ub, io);
+	if (!ret)
+		ret = ublk_config_io_buf(ub, io, cmd, buf_addr, NULL);
 	mutex_unlock(&ub->mutex);
 	return ret;
 }