block: Introduce op_needs_zoned_write_locking()

Introduce a helper function for checking whether write serialization is
required if the operation will be sent to a zoned device. A second caller
for op_needs_zoned_write_locking() will be introduced in the next patch
in this series.
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230517174230.897144-5-bvanassche@acm.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/blkdev.h

@@ -1281,13 +1281,16 @@ static inline unsigned int bdev_zone_no(struct block_device *bdev, sector_t sec)
 	return disk_zone_no(bdev->bd_disk, sec);
 }
 
+/* Whether write serialization is required for @op on zoned devices. */
+static inline bool op_needs_zoned_write_locking(enum req_op op)
+{
+	return op == REQ_OP_WRITE || op == REQ_OP_WRITE_ZEROES;
+}
+
 static inline bool bdev_op_is_zoned_write(struct block_device *bdev,
 					  enum req_op op)
 {
-	if (!bdev_is_zoned(bdev))
-		return false;
-
-	return op == REQ_OP_WRITE || op == REQ_OP_WRITE_ZEROES;
+	return bdev_is_zoned(bdev) && op_needs_zoned_write_locking(op);
 }
 
 static inline sector_t bdev_zone_sectors(struct block_device *bdev)