From: Jens Axboe <axboe@kernel.dk>
Date: Thu, 11 Feb 2021 15:35:43 +0000 (-0700)
Subject: iomap: relax memory alignment restriction for O_DIRECT
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=refs%2Fheads%2Fdio-mem-align;p=linux-2.6-block.git

iomap: relax memory alignment restriction for O_DIRECT

We currently require blocksize alignment for both position/length and the
memory range. The latter is overly restrictive, as most devices can do DMA
at a much finer granularity.

Honor the bdev setting for DMA alignment, and use that for checking if we
can process the IO or need to error it.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 933f234d5bec..7f962011fa0c 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -207,7 +207,8 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 {
 	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);
+	struct request_queue *q = bdev_get_queue(iomap->bdev);
+	unsigned long mem_align = q->dma_alignment;
 	struct bio *bio;
 	bool need_zeroout = false;
 	bool use_fua = false;
@@ -215,7 +216,9 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 	size_t copied = 0;
 	size_t orig_count;
 
-	if ((pos | length | align) & ((1 << blkbits) - 1))
+	if ((pos | length) & ((1 << blkbits) - 1))
+		return -EINVAL;
+	if (iov_iter_alignment(dio->submit.iter) & mem_align)
 		return -EINVAL;
 
 	if (iomap->type == IOMAP_UNWRITTEN) {
@@ -237,8 +240,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 		 * cache flushes on IO completion.
 		 */
 		if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) &&
-		    (dio->flags & IOMAP_DIO_WRITE_FUA) &&
-		    blk_queue_fua(bdev_get_queue(iomap->bdev)))
+		    (dio->flags & IOMAP_DIO_WRITE_FUA) && blk_queue_fua(q))
 			use_fua = true;
 	}