Re: [PATCH v6 5/7] xfs: switch to multigrain timestamps

Jeff Layton
2023-08-02T18:22:06Z

On Wed, 2023-08-02 at 10:48 -0700, Darrick J. Wong wrote:
> On Tue, Jul 25, 2023 at 10:58:18AM -0400, Jeff Layton wrote:
> > Enable multigrain timestamps, which should ensure that there is an
> > apparent change to the timestamp whenever it has been written after
> > being actively observed via getattr.
> >
> > Also, anytime the mtime changes, the ctime must also change, and those
> > are now the only two options for xfs_trans_ichgtime. Have that function
> > unconditionally bump the ctime, and ASSERT that XFS_ICHGTIME_CHG is
> > always set.
> >
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > ---
> > fs/xfs/libxfs/xfs_trans_inode.c | 6 +++---
> > fs/xfs/xfs_iops.c | 4 ++--
> > fs/xfs/xfs_super.c | 2 +-
> > 3 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_trans_inode.c b/fs/xfs/libxfs/xfs_trans_inode.c
> > index 6b2296ff248a..ad22656376d3 100644
> > --- a/fs/xfs/libxfs/xfs_trans_inode.c
> > +++ b/fs/xfs/libxfs/xfs_trans_inode.c
> > @@ -62,12 +62,12 @@ xfs_trans_ichgtime(
> > ASSERT(tp);
> > ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
> >
> > - tv = current_time(inode);
> > + /* If the mtime changes, then ctime must also change */
> > + ASSERT(flags & XFS_ICHGTIME_CHG);
> >
> > + tv = inode_set_ctime_current(inode);
> > if (flags & XFS_ICHGTIME_MOD)
> > inode->i_mtime = tv;
> > - if (flags & XFS_ICHGTIME_CHG)
> > - inode_set_ctime_to_ts(inode, tv);
> > if (flags & XFS_ICHGTIME_CREATE)
> > ip->i_crtime = tv;
> > }
> > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> > index 3a9363953ef2..3f89ef5a2820 100644
> > --- a/fs/xfs/xfs_iops.c
> > +++ b/fs/xfs/xfs_iops.c
> > @@ -573,10 +573,10 @@ 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_get_ctime(inode);
> > stat->blocks = XFS_FSB_TO_BB(mp, ip->i_nblocks + ip->i_delayed_blks);
> >
> > + fill_mg_cmtime(request_mask, inode, stat);
>
> Huh. I would've thought @stat would come first since that's what we're
> acting upon, but ... eh. :)
>
> If everyone else is ok with the fill_mg_cmtime signature,
> Acked-by: Darrick J. Wong <djwong@kernel.org>
>
>

Good point. We can change the signature. I think xfs is the only caller
outside of the generic vfs right now, and it'd be best to do it now.

Christian, would you prefer that I send an updated series, or patches on
top of vfs.ctime that can be folded in?

--
Jeff Layton <jlayton@kernel.org>