block: introduce bdev_iter_is_aligned helper

Provide a convenient function for this repeatable coding pattern.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220610195830.3574005-10-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/blkdev.h

@@ -1370,6 +1370,13 @@ static inline unsigned int bdev_dma_alignment(struct block_device *bdev)
 	return queue_dma_alignment(bdev_get_queue(bdev));
 }
 
+static inline bool bdev_iter_is_aligned(struct block_device *bdev,
+					struct iov_iter *iter)
+{
+	return iov_iter_is_aligned(iter, bdev_dma_alignment(bdev),
+				   bdev_logical_block_size(bdev) - 1);
+}
+
 static inline int blk_rq_aligned(struct request_queue *q, unsigned long addr,
 				 unsigned int len)
 {