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

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.

However, if we need more fields as Avi Kivity requested at
https://lore.kernel.org/r/6c06b2d4-2d96-c4a6-7aca-5147a91e7cf2@scylladb.com (local)
that is going to complicate things.  I haven't had a chance to look
into whether those extra fields are really needed.  Your opinion on whether XFS
(and any other filesystem) needs them would be appreciated.

And I guess you're tabling the "optimal" IO discussions for now, because
there are too many variants of what that means?

Yes, that's omitted for now due to the apparent redundancy with stx_blksize.

- Eric