iomap: add support for dma aligned direct-io

Use the address alignment requirements from the block_device for direct
io instead of requiring addresses be aligned to the block size.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220610195830.3574005-12-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/iomap/direct-io.c

@@ -242,7 +242,6 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
 	struct inode *inode = iter->inode;
 	unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
 	unsigned int fs_block_size = i_blocksize(inode), pad;
-	unsigned int align = iov_iter_alignment(dio->submit.iter);
 	loff_t length = iomap_length(iter);
 	loff_t pos = iter->pos;
 	unsigned int bio_opf;
@@ -253,7 +252,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
 	size_t copied = 0;
 	size_t orig_count;
 
-	if ((pos | length | align) & ((1 << blkbits) - 1))
+	if ((pos | length) & ((1 << blkbits) - 1) ||
+	    !bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
 		return -EINVAL;
 
 	if (iomap->type == IOMAP_UNWRITTEN) {