2022-08-22 13:46:47

by Jeff Layton

Subject: [PATCH v2] xfs: don't bump the i_version on an atime update in xfs_vn_update_time

xfs will update the i_version when updating only the atime value, which
is not desirable for any of the current consumers of i_version. Doing so
leads to unnecessary cache invalidations on NFS and extra measurement
activity in IMA.

Add a new XFS_ILOG_NOIVER flag, and use that to indicate that the
transaction should not update the i_version. Set that value in
xfs_vn_update_time if we're only updating the atime.

Cc: Dave Chinner <[email protected]>
Cc: NeilBrown <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: David Wysochanski <[email protected]>
Signed-off-by: Jeff Layton <[email protected]>
---
fs/xfs/libxfs/xfs_log_format.h | 2 +-
fs/xfs/libxfs/xfs_trans_inode.c | 2 +-
fs/xfs/xfs_iops.c | 11 +++++++++--
3 files changed, 11 insertions(+), 4 deletions(-)

v2: don't set the NOIVERS flag if S_VERSION is set

diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
index b351b9dc6561..866a4c5cf70c 100644
--- a/fs/xfs/libxfs/xfs_log_format.h
+++ b/fs/xfs/libxfs/xfs_log_format.h
@@ -323,7 +323,7 @@ struct xfs_inode_log_format_32 {
#define XFS_ILOG_ABROOT 0x100 /* log i_af.i_broot */
#define XFS_ILOG_DOWNER 0x200 /* change the data fork owner on replay */
#define XFS_ILOG_AOWNER 0x400 /* change the attr fork owner on replay */
-
+#define XFS_ILOG_NOIVER 0x800 /* don't bump i_version */

/*
* The timestamps are dirty, but not necessarily anything else in the inode
diff --git a/fs/xfs/libxfs/xfs_trans_inode.c b/fs/xfs/libxfs/xfs_trans_inode.c
index 8b5547073379..ffe6d296e7f9 100644
--- a/fs/xfs/libxfs/xfs_trans_inode.c
+++ b/fs/xfs/libxfs/xfs_trans_inode.c
@@ -126,7 +126,7 @@ xfs_trans_log_inode(
* unconditionally.
*/
if (!test_and_set_bit(XFS_LI_DIRTY, &iip->ili_item.li_flags)) {
- if (IS_I_VERSION(inode) &&
+ if (!(flags & XFS_ILOG_NOIVER) && IS_I_VERSION(inode) &&
inode_maybe_inc_iversion(inode, flags & XFS_ILOG_CORE))
iversion_flags = XFS_ILOG_CORE;
}
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 45518b8c613c..94f14d96641b 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1041,10 +1041,17 @@ xfs_vn_update_time(
return error;

xfs_ilock(ip, XFS_ILOCK_EXCL);
- if (flags & S_CTIME)
+
+ if (!(flags & S_VERSION))
+ log_flags |= XFS_ILOG_NOIVER;
+ if (flags & S_CTIME) {
inode->i_ctime = *now;
- if (flags & S_MTIME)
+ log_flags &= ~XFS_ILOG_NOIVER;
+ }
+ if (flags & S_MTIME) {
inode->i_mtime = *now;
+ log_flags &= ~XFS_ILOG_NOIVER;
+ }
if (flags & S_ATIME)
inode->i_atime = *now;

--
2.37.2

2022-08-22 23:45:13

by Dave Chinner

Subject: Re: [PATCH v2] xfs: don't bump the i_version on an atime update in xfs_vn_update_time

On Mon, Aug 22, 2022 at 09:40:11AM -0400, Jeff Layton wrote:
> xfs will update the i_version when updating only the atime value, which
> is not desirable for any of the current consumers of i_version. Doing so
> leads to unnecessary cache invalidations on NFS and extra measurement
> activity in IMA.
>
> Add a new XFS_ILOG_NOIVER flag, and use that to indicate that the
> transaction should not update the i_version. Set that value in
> xfs_vn_update_time if we're only updating the atime.
>
> Cc: Dave Chinner <[email protected]>
> Cc: NeilBrown <[email protected]>
> Cc: Trond Myklebust <[email protected]>
> Cc: David Wysochanski <[email protected]>
> Signed-off-by: Jeff Layton <[email protected]>

NACK.

We need to define exactly what iversion covers first before we go
changing how filesystems update it. We only want to change iversion
behaviour once, and we want it done right the first time.

-Dave.
--
Dave Chinner
[email protected]