Re: [RFC PATCH 3/3][RESEND] xfs: mark the inode for high-res timestamp update in getattr

Darrick J. Wong
2023-04-11T14:55:16Z

On Tue, Apr 11, 2023 at 10:37:02AM -0400, Jeff Layton wrote:
> When the mtime or ctime is being queried via getattr, ensure that we
> mark the inode for a high-res timestamp update on the next pass. Also,
> switch to current_cmtime for other c/mtime updates.
>
> With this change, we're better off having the NFS server just ignore
> the i_version field and have it use the ctime instead, so clear the
> STATX_CHANGE_COOKIE flag in the result mask in ->getattr.
>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
> fs/xfs/libxfs/xfs_trans_inode.c | 2 +-
> fs/xfs/xfs_acl.c | 2 +-
> fs/xfs/xfs_inode.c | 2 +-
> fs/xfs/xfs_iops.c | 15 ++++++++++++---
> 4 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_trans_inode.c b/fs/xfs/libxfs/xfs_trans_inode.c
> index 8b5547073379..9ad7c229c617 100644
> --- a/fs/xfs/libxfs/xfs_trans_inode.c
> +++ b/fs/xfs/libxfs/xfs_trans_inode.c
> @@ -63,7 +63,7 @@ xfs_trans_ichgtime(
> ASSERT(tp);
> ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
>
> - tv = current_time(inode);
> + tv = current_cmtime(inode);
>
> if (flags & XFS_ICHGTIME_MOD)
> inode->i_mtime = tv;
> diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
> index 791db7d9c849..461adc58cf8c 100644
> --- a/fs/xfs/xfs_acl.c
> +++ b/fs/xfs/xfs_acl.c
> @@ -233,7 +233,7 @@ xfs_acl_set_mode(
> xfs_ilock(ip, XFS_ILOCK_EXCL);
> xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
> inode->i_mode = mode;
> - inode->i_ctime = current_time(inode);
> + inode->i_ctime = current_cmtime(inode);

Hmm, now we're adding a spinlock to all these updates.
Does lockdep have anything exciting to say about this?

(I don't think it will, just wondering aloud...)

> xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
>
> if (xfs_has_wsync(mp))
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 5808abab786c..80f9d731e261 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -843,7 +843,7 @@ xfs_init_new_inode(
> ip->i_df.if_nextents = 0;
> ASSERT(ip->i_nblocks == 0);
>
> - tv = current_time(inode);
> + tv = current_cmtime(inode);
> inode->i_mtime = tv;
> inode->i_atime = tv;
> inode->i_ctime = tv;
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 24718adb3c16..a0b07f90e16c 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -565,6 +565,15 @@ xfs_vn_getattr(
> if (xfs_is_shutdown(mp))
> return -EIO;
>
> + /*
> + * XFS uses the i_version infrastructure to track any change to
> + * the inode, including atime updates. This means that the i_version
> + * returned by getattr doesn't conform to what the callers expect.
> + * Clear it here so that nfsd will fake up a change cookie from the
> + * ctime instead.
> + */
> + stat->result_mask &= ~STATX_CHANGE_COOKIE;
> +
> stat->size = XFS_ISIZE(ip);
> stat->dev = inode->i_sb->s_dev;
> stat->mode = inode->i_mode;
> @@ -573,8 +582,8 @@ xfs_vn_getattr(
> stat->gid = vfsgid_into_kgid(vfsgid);
> stat->ino = ip->i_ino;
> stat->atime = inode->i_atime;
> - stat->mtime = inode->i_mtime;
> - stat->ctime = inode->i_ctime;
> + if (request_mask & (STATX_CTIME|STATX_MTIME))
> + fill_cmtime_and_mark(inode, stat);

Should we be setting STATX_[CM]TIME in the result_mask, just in case the
caller asked for ctime and not mtime?

--D

> stat->blocks = XFS_FSB_TO_BB(mp, ip->i_nblocks + ip->i_delayed_blks);
>
> if (xfs_has_v3inodes(mp)) {
> @@ -917,7 +926,7 @@ xfs_setattr_size(
> if (newsize != oldsize &&
> !(iattr->ia_valid & (ATTR_CTIME | ATTR_MTIME))) {
> iattr->ia_ctime = iattr->ia_mtime =
> - current_time(inode);
> + current_cmtime(inode);
> iattr->ia_valid |= ATTR_CTIME | ATTR_MTIME;
> }
>
> --
> 2.39.2
>