On Thu, Jun 23, 2022 at 10:23:20AM -0700, Eric Biggers wrote:

On Thu, Jun 23, 2022 at 08:58:12AM -0700, Darrick J. Wong wrote:

quoted

quoted

diff --git a/include/linux/stat.h b/include/linux/stat.h
index 7df06931f25d8..ff277ced50e9f 100644
--- a/include/linux/stat.h
+++ b/include/linux/stat.h

@@ -50,6 +50,8 @@ struct kstat {
 	struct timespec64 btime;			/* File creation time */
 	u64		blocks;
 	u64		mnt_id;
+	u32		dio_mem_align;
+	u32		dio_offset_align;

Hmm.  Does the XFS port of XFS_IOC_DIOINFO to STATX_DIOALIGN look like
this?

	struct xfs_buftarg	*target = xfs_inode_buftarg(ip);

	kstat.dio_mem_align = target->bt_logical_sectorsize;
	kstat.dio_offset_align = target->bt_logical_sectorsize;
	kstat.result_mask |= STATX_DIOALIGN;

Yes, I think so.

By the way, the patchset "[PATCHv6 00/11] direct-io dma alignment"
(https://lore.kernel.org/linux-block/20220610195830.3574005-1-kbusch@fb.com/T/#u (local)),
which is currently queued in linux-block/for-next for 5.20, will relax the user
buffer alignment requirement to the dma alignment for all filesystems using the
iomap direct I/O implementation.  If that goes in, the XFS implementation of
STATX_DIOALIGN, as well as the ext4 and f2fs ones, will need to be changed
accordingly.  Also, the existing XFS_IOC_DIOINFO will need to be changed.

- Eric