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Date:   Thu, 3 Aug 2023 09:05:55 +0200
From:   Christian Brauner <brauner@kernel.org>
To:     Jeff Layton <jlayton@kernel.org>
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Subject: Re: [PATCH v6 5/7] xfs: switch to multigrain timestamps
Message-ID: <20230803-mulmig-rennen-adbe9b2a6608@brauner>
References: <20230725-mgctime-v6-0-a794c2b7abca@kernel.org>
 <20230725-mgctime-v6-5-a794c2b7abca@kernel.org>
 <20230802174853.GC11352@frogsfrogsfrogs>
 <16f46a9e6d88582d53d31a320589a7ba9d232e0c.camel@kernel.org>
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In-Reply-To: <16f46a9e6d88582d53d31a320589a7ba9d232e0c.camel@kernel.org>
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On Wed, Aug 02, 2023 at 02:21:49PM -0400, Jeff Layton wrote:
> 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?

Let's fold instead of inundate everyone with almost 100 patches.
When I'll apply I'll remind everyone where the series can be pulled
from anyway.