On Sun, Nov 24, 2019 at 09:31:45PM +0200, Amir Goldstein wrote:
> Push clamping timestamps down the call stack into notify_change(), so
> in-kernel callers like nfsd and overlayfs will get similar timestamp
> set behavior as utimes.
So, nfsd has always bypassed timestamp_truncate() and we've never
noticed till now? What are the symptoms? (Do timestamps go backwards
after cache eviction on filesystems with large time granularity?)
Looks like generic/402 has never run in my tests:
generic/402 [not run] no kernel support for y2038 sysfs switch
--b.
>
> Suggested-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> Fixes: 42e729b9ddbb ("utimes: Clamp the timestamps before update")
> Cc: stable@xxxxxxxxxxxxxxx # v5.4
> Cc: Deepa Dinamani <deepa.kernel@xxxxxxxxx>
> Cc: Jeff Layton <jlayton@xxxxxxxxxx>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
>
> Arnd,
>
> This fixes xfstest generic/402 when run with -overlay setup.
> Note that running the test requires latest xfstests with:
> acb2ba78 - overlay: support timestamp range check
>
> I had previously posted a fix specific for overlayfs [1],
> but Miklos suggested this more generic fix, which should also
> serve nfsd and other in-kernel users.
>
> I tested this change with test generic/402 on ext4/xfs/btrfs
> and overlayfs, but not with nfsd.
>
> Jeff, could you ack this change is good for nfsd as well?
>
> Thanks,
> Amir.
>
> [1] https://lore.kernel.org/linux-fsdevel/20191111073000.2957-1-amir73il@xxxxxxxxx/
>
> fs/attr.c | 5 +++++
> fs/utimes.c | 4 ++--
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/fs/attr.c b/fs/attr.c
> index df28035aa23e..e8de5e636e66 100644
> --- a/fs/attr.c
> +++ b/fs/attr.c
> @@ -268,8 +268,13 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de
> attr->ia_ctime = now;
> if (!(ia_valid & ATTR_ATIME_SET))
> attr->ia_atime = now;
> + else
> + attr->ia_atime = timestamp_truncate(attr->ia_atime, inode);
> if (!(ia_valid & ATTR_MTIME_SET))
> attr->ia_mtime = now;
> + else
> + attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode);
> +
> if (ia_valid & ATTR_KILL_PRIV) {
> error = security_inode_need_killpriv(dentry);
> if (error < 0)
> diff --git a/fs/utimes.c b/fs/utimes.c
> index 1ba3f7883870..090739322463 100644
> --- a/fs/utimes.c
> +++ b/fs/utimes.c
> @@ -36,14 +36,14 @@ static int utimes_common(const struct path *path, struct timespec64 *times)
> if (times[0].tv_nsec == UTIME_OMIT)
> newattrs.ia_valid &= ~ATTR_ATIME;
> else if (times[0].tv_nsec != UTIME_NOW) {
> - newattrs.ia_atime = timestamp_truncate(times[0], inode);
> + newattrs.ia_atime = times[0];
> newattrs.ia_valid |= ATTR_ATIME_SET;
> }
>
> if (times[1].tv_nsec == UTIME_OMIT)
> newattrs.ia_valid &= ~ATTR_MTIME;
> else if (times[1].tv_nsec != UTIME_NOW) {
> - newattrs.ia_mtime = timestamp_truncate(times[1], inode);
> + newattrs.ia_mtime = times[1];
> newattrs.ia_valid |= ATTR_MTIME_SET;
> }
> /*
> --
> 2.17.1
