linux-kernel - Re: [PATCH v2 3/7] nfsd: use ATTR_CTIME

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Message-ID: <8ec5b19dc1d0ce26f1cd86d7db2ba5a2d260c073.camel@kernel.org>
Date: Sat, 26 Jul 2025 15:03:53 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, Alexander Viro	
 <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara
	 <jack@...e.cz>, Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu	
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
 NeilBrown <neil@...wn.name>, Olga Kornievskaia <okorniev@...hat.com>, Dai
 Ngo <Dai.Ngo@...cle.com>,  Tom Talpey <tom@...pey.com>
Cc: Trond Myklebust <trondmy@...merspace.com>, Anna Schumaker
 <anna@...nel.org>, 	linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org, 	linux-trace-kernel@...r.kernel.org,
 linux-nfs@...r.kernel.org
Subject: Re: [PATCH v2 3/7] nfsd: use ATTR_CTIME_SET for delegated ctime
 updates

On Sat, 2025-07-26 at 14:48 -0400, Chuck Lever wrote:
> Hi Jeff -
> 
> Thanks again for your focus on getting this straightened out!
> 
> 
> On 7/26/25 10:31 AM, Jeff Layton wrote:
> > Ensure that notify_change() doesn't clobber a delegated ctime update
> > with current_time() by setting ATTR_CTIME_SET for those updates.
> > 
> > Also, set the tv_nsec field the nfsd4_decode_fattr4 to the correct
> > value.
> 
> I don't yet see the connection of the above tv_nsec fix to the other
> changes in this patch. Wouldn't this be an independent fix?
> 

I felt like they were related. Yes, the ia_ctime field is currently
being set wrong, but it's also being clobbered by notify_change(), so
it doesn't matter much. I can break this into a separate patch (with a
Fixes: tag) if you prefer though.

> > Don't bother setting the timestamps in cb_getattr_update_times() in the
> > non-delegated case. notify_change() will do that itself.
> > 
> > Signed-off-by: Jeff Layton <jlayton@...nel.org>
> 
> General comments:
> 
> I don't feel that any of the patches in this series need to be tagged
> for stable, since there is already a Kconfig setting that defaults to
> leaving timestamp delegation disabled. But I would like to see Fixes:
> tags, where that makes sense?
> 

I don't think any of these need to go to stable since this is still
under a non-default Kconfig option, and the main effect of the bug is
wonky timestamps. I should be able to add some Fixes: tags though.

> Is this set on top of the set you posted a day or two ago with the new
> trace point? Or does this set replace that one?
> 

This set should replace those.

> 
> > ---
> >  fs/nfsd/nfs4state.c | 6 +++---
> >  fs/nfsd/nfs4xdr.c   | 5 +++--
> >  2 files changed, 6 insertions(+), 5 deletions(-)
> > 
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 88c347957da5b8f352be63f84f207d2225f81cb9..77eea2ad93cc07939f045fc4b983b1ac00d068b8 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -9167,7 +9167,6 @@ static bool set_cb_time(struct timespec64 *cb, const struct timespec64 *orig,
> >  static int cb_getattr_update_times(struct dentry *dentry, struct nfs4_delegation *dp)
> >  {
> >  	struct inode *inode = d_inode(dentry);
> > -	struct timespec64 now = current_time(inode);
> >  	struct nfs4_cb_fattr *ncf = &dp->dl_cb_fattr;
> >  	struct iattr attrs = { };
> >  	int ret;
> > @@ -9175,6 +9174,7 @@ static int cb_getattr_update_times(struct dentry *dentry, struct nfs4_delegation
> >  	if (deleg_attrs_deleg(dp->dl_type)) {
> >  		struct timespec64 atime = inode_get_atime(inode);
> >  		struct timespec64 mtime = inode_get_mtime(inode);
> > +		struct timespec64 now = current_time(inode);
> >  
> >  		attrs.ia_atime = ncf->ncf_cb_atime;
> >  		attrs.ia_mtime = ncf->ncf_cb_mtime;
> > @@ -9183,12 +9183,12 @@ static int cb_getattr_update_times(struct dentry *dentry, struct nfs4_delegation
> >  			attrs.ia_valid |= ATTR_ATIME | ATTR_ATIME_SET;
> >  
> >  		if (set_cb_time(&attrs.ia_mtime, &mtime, &now)) {
> > -			attrs.ia_valid |= ATTR_CTIME | ATTR_MTIME | ATTR_MTIME_SET;
> > +			attrs.ia_valid |= ATTR_CTIME | ATTR_CTIME_SET |
> > +					  ATTR_MTIME | ATTR_MTIME_SET;
> >  			attrs.ia_ctime = attrs.ia_mtime;
> >  		}
> >  	} else {
> >  		attrs.ia_valid |= ATTR_MTIME | ATTR_CTIME;
> > -		attrs.ia_mtime = attrs.ia_ctime = now;
> >  	}
> >  
> >  	if (!attrs.ia_valid)
> > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> > index 8b68f74a8cf08c6aa1305a2a3093467656085e4a..c0a3c6a7c8bb70d62940115c3101e9f897401456 100644
> > --- a/fs/nfsd/nfs4xdr.c
> > +++ b/fs/nfsd/nfs4xdr.c
> > @@ -538,8 +538,9 @@ nfsd4_decode_fattr4(struct nfsd4_compoundargs *argp, u32 *bmval, u32 bmlen,
> >  		iattr->ia_mtime.tv_sec = modify.seconds;
> >  		iattr->ia_mtime.tv_nsec = modify.nseconds;
> >  		iattr->ia_ctime.tv_sec = modify.seconds;
> > -		iattr->ia_ctime.tv_nsec = modify.seconds;
> > -		iattr->ia_valid |= ATTR_CTIME | ATTR_MTIME | ATTR_MTIME_SET | ATTR_DELEG;
> > +		iattr->ia_ctime.tv_nsec = modify.nseconds;
> > +		iattr->ia_valid |= ATTR_CTIME | ATTR_CTIME_SET |
> > +				   ATTR_MTIME | ATTR_MTIME_SET | ATTR_DELEG;
> >  	}
> >  
> >  	/* request sanity: did attrlist4 contain the expected number of words? */
> > 
> 
> 

-- 
Jeff Layton <jlayton@...nel.org>