[PATCH] xfs: reinstate the old i_version counter as STATX_CHANGE_COOKIE

[Jeff Layton <jlayton@kernel.org>]

The handling of STATX_CHANGE_COOKIE was moved into generic_fillattr in
commit 0d72b92883c6 (fs: pass the request_mask to generic_fillattr), but
we didn't account for the fact that xfs doesn't call generic_fillattr at
all.

Make XFS report its i_version as the STATX_CHANGE_COOKIE.

Fixes: 0d72b92883c6 (fs: pass the request_mask to generic_fillattr)
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
I had hoped to fix this in a better way with the multigrain patches, but
it's taking longer than expected (if it even pans out at this point).

Until then, make sure we use XFS's i_version as the STATX_CHANGE_COOKIE,
even if it's bumped due to atime updates. Too many invalidations is
preferable to not enough.
---
 fs/xfs/xfs_iops.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 1c1e6171209d..2b3b05c28e9e 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -584,6 +584,11 @@ xfs_vn_getattr(
 		}
 	}
 
+	if ((request_mask & STATX_CHANGE_COOKIE) && IS_I_VERSION(inode)) {
+		stat->change_cookie = inode_query_iversion(inode);
+		stat->result_mask |= STATX_CHANGE_COOKIE;
+	}
+
 	/*
 	 * Note: If you add another clause to set an attribute flag, please
 	 * update attributes_mask below.

---
base-commit: df964ce9ef9fea10cf131bf6bad8658fde7956f6
change-id: 20230929-xfs-iversion-819fa2c18591

Best regards,
-- 
Jeff Layton <jlayton@kernel.org>