[PATCHv4 9/9] fs: add support for dma aligned direct-io

[Keith Busch <kbusch@fb.com>]

From: Keith Busch <kbusch@kernel.org>

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

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 fs/direct-io.c       | 11 +++++++----
 fs/iomap/direct-io.c |  3 ++-
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 840752006f60..64cc176be60c 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1131,7 +1131,7 @@ ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 	struct dio_submit sdio = { 0, };
 	struct buffer_head map_bh = { 0, };
 	struct blk_plug plug;
-	unsigned long align = offset | iov_iter_alignment(iter);
+	unsigned long align = iov_iter_alignment(iter);
 
 	/*
 	 * Avoid references to bdev if not absolutely needed to give
@@ -1165,11 +1165,14 @@ ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 		goto fail_dio;
 	}
 
-	if (align & blocksize_mask) {
-		if (bdev)
+	if ((offset | align) & blocksize_mask) {
+		if (bdev) {
 			blkbits = blksize_bits(bdev_logical_block_size(bdev));
+			if (align & bdev_dma_alignment(bdev))
+				goto fail_dio;
+		}
 		blocksize_mask = (1 << blkbits) - 1;
-		if (align & blocksize_mask)
+		if ((offset | count) & blocksize_mask)
 			goto fail_dio;
 	}
 
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 80f9b047aa1b..0256d28baa8e 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -244,7 +244,8 @@ 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) ||
+	    align & bdev_dma_alignment(iomap->bdev))
 		return -EINVAL;
 
 	if (iomap->type == IOMAP_UNWRITTEN) {
-- 
2.30.2