iomap: open code bio_iov_iter_get_bdev_pages

Prepare for passing different alignments, and to retired
bio_iov_iter_get_bdev_pages as a global helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

fs/iomap/direct-io.c

@@ -433,7 +433,8 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
 		bio->bi_private = dio;
 		bio->bi_end_io = iomap_dio_bio_end_io;
 
-		ret = bio_iov_iter_get_bdev_pages(bio, dio->submit.iter, iomap->bdev);
+		ret = bio_iov_iter_get_pages(bio, dio->submit.iter,
+				bdev_logical_block_size(iomap->bdev) - 1);
 		if (unlikely(ret)) {
 			/*
 			 * We have to stop part way through an IO. We must fall