On Thu, 06 Nov 2025, Chuck Lever wrote:

From: Chuck Lever chuck.lever@oracle.com

Mike noted that when NFSD responds to an NFS_FILE_SYNC WRITE, it does not also persist file time stamps. To wit, Section 18.32.3 of RFC 8881 mandates:

...

The client specifies with the stable parameter the method of how the data is to be processed by the server. If stable is FILE_SYNC4, the server MUST commit the data written plus all file system metadata to stable storage before returning results. This corresponds to the NFSv2 protocol semantics. Any other behavior constitutes a protocol violation. If stable is DATA_SYNC4, then the server MUST commit all of the data to stable storage and enough of the metadata to retrieve the data before returning.

Commit 3f3503adb332 ("NFSD: Use vfs_iocb_iter_write()") replaced:

• flags |= RWF_SYNC;
  
  

with:

• kiocb.ki_flags |= IOCB_DSYNC;
  
  

which appears to be correct given:

if (flags & RWF_SYNC) kiocb_flags |= IOCB_DSYNC;

in kiocb_set_rw_flags(). However the author of that commit did not

"the author and reviewers of that commit"

Reviewed-by: NeilBrown neil@brown.name

Thanks, NeilBrown

appreciate that the previous line in kiocb_set_rw_flags() results in IOCB_SYNC also being set:

kiocb_flags |= (__force int) (flags & RWF_SUPPORTED);

RWF_SUPPORTED contains RWF_SYNC, and RWF_SYNC is the same bit as IOCB_SYNC. Reviewers at the time did not catch the omission.

Reported-by: Mike Snitzer snitzer@kernel.org Closes: https://lore.kernel.org/linux-nfs/20251018005431.3403-1-cel@kernel.org/T/#t Reviewed-by: Jeff Layton jlayton@kernel.org Fixes: 3f3503adb332 ("NFSD: Use vfs_iocb_iter_write()") Cc: stable@vger.kernel.org Signed-off-by: Chuck Lever chuck.lever@oracle.com

---

fs/nfsd/vfs.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index f537a7b4ee01..5333d49910d9 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1314,8 +1314,18 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, stable = NFS_UNSTABLE; init_sync_kiocb(&kiocb, file); kiocb.ki_pos = offset;

• if (stable && !fhp->fh_use_wgather)

• kiocb.ki_flags |= IOCB_DSYNC;
  

• if (likely(!fhp->fh_use_wgather)) {

• switch (stable) {
  

• case NFS_FILE_SYNC:
  

• 	/* persist data and timestamps */
  

• 	kiocb.ki_flags |= IOCB_DSYNC | IOCB_SYNC;
  

• 	break;
  

• case NFS_DATA_SYNC:
  

• 	/* persist data only */
  

• 	kiocb.ki_flags |= IOCB_DSYNC;
  

• 	break;
  

• }
  

• }

nvecs = xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, payload); iov_iter_bvec(&iter, ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt); -- 2.51.0