Re: [PATCH 1/1] nfsd: update mtime/ctime on CLONE and COPY in presence of delegated attributes

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2026-04-03 at 12:53 -0400, Olga Kornievskaia wrote:
> When delegated attributes are given on open the file is opened with NOCMTIME
> and modifying operations do not update mtime/ctime as to not get out-of-sync
> with the client's delegated view. However, for operations CLONE/COPY server
> should update its view of mtime/ctime and reflect that in any GETATTR queries.
> 
> Fixes: e5e9b24ab8fa ("nfsd: freeze c/mtime updates with outstanding WRITE_ATTRS delegation")
> Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
> ---
>  fs/nfsd/nfs4proc.c | 27 ++++++++++++++++++++++++++-
>  1 file changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 99b44b6ec056..66bde3732b03 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1396,6 +1396,24 @@ nfsd4_verify_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	goto out;
>  }
>  
> +static bool nfsd4_clear_nocmtime(struct file *f)
> +{
> +	if ((READ_ONCE(f->f_mode) & FMODE_NOCMTIME) != 0) {
> +		spin_lock(&f->f_lock);
> +		f->f_mode &= ~FMODE_NOCMTIME;
> +		spin_unlock(&f->f_lock);
> +		return true;
> +	}
> +	return false;
> +}
> +
> +static void nfsd4_restore_nocmtime(struct file *f)
> +{
> +	spin_lock(&f->f_lock);
> +	f->f_mode |= FMODE_NOCMTIME;
> +	spin_unlock(&f->f_lock);
> +}
> +
>  static __be32
>  nfsd4_clone(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  		union nfsd4_op_u *u)
> @@ -1403,16 +1421,19 @@ nfsd4_clone(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	struct nfsd4_clone *clone = &u->clone;
>  	struct nfsd_file *src, *dst;
>  	__be32 status;
> +	bool restore_nocmtime = false;
>  
>  	status = nfsd4_verify_copy(rqstp, cstate, &clone->cl_src_stateid, &src,
>  				   &clone->cl_dst_stateid, &dst);
>  	if (status)
>  		goto out;
>  
> +	restore_nocmtime = nfsd4_clear_nocmtime(dst->nf_file);
>  	status = nfsd4_clone_file_range(rqstp, src, clone->cl_src_pos,
>  			dst, clone->cl_dst_pos, clone->cl_count,
>  			EX_ISSYNC(cstate->current_fh.fh_export));
> -
> +	if (restore_nocmtime)
> +		nfsd4_restore_nocmtime(dst->nf_file);
>  	nfsd_file_put(dst);
>  	nfsd_file_put(src);
>  out:
> @@ -2132,6 +2153,7 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	struct nfsd4_copy *copy = &u->copy;
>  	struct nfsd42_write_res *result;
>  	__be32 status;
> +	bool restore_nocmtime = false;
>  
>  	result = &copy->cp_res;
>  	nfsd_copy_write_verifier((__be32 *)&result->wr_verifier.data, nn);
> @@ -2157,6 +2179,7 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  		}
>  	}
>  
> +	restore_nocmtime = nfsd4_clear_nocmtime(copy->nf_dst->nf_file);
>  	memcpy(&copy->fh, &cstate->current_fh.fh_handle,
>  		sizeof(struct knfsd_fh));
>  	if (nfsd4_copy_is_async(copy)) {
> @@ -2199,6 +2222,8 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  				       copy->nf_dst->nf_file, true);
>  	}
>  out:
> +	if (restore_nocmtime)
> +		nfsd4_restore_nocmtime(copy->nf_dst->nf_file);
>  	trace_nfsd_copy_done(copy, status);
>  	release_copy_files(copy);
>  	return status;

This seems simple enough, but there is some raciness involved if other
calls are running concurrently with the COPY/CLONE. You might end up
reenabling FMODE_NOCMTIME before a second COPY/CLONE finishes.

A simpler idea might be to just do a notify_change() for ATTR_MTIME
after each COPY or CLONE operation done on a file with FMODE_NOCMTIME
set.

That should set the timestamp to something pretty close to whatever the
last write() would have set it to, but without having to monkey with
the fmode.
-- 
Jeff Layton <jlayton@kernel.org>