Re: [PATCH] ecryptfs: set s_time_gran to get correct time granularity

Dear all,

On Fri, Dec 6, 2024 at 1:29 PM Bert Wesarg <[email protected]> wrote:
>
> Hi,
>
> On 17.05.24 12:09, Frank Hsiao 蕭法宣 wrote:
> > related to: https://bugs.launchpad.net/ecryptfs/+bug/1890486
> >
> > This bug happens in the two following situations:
> > cp -p: copy a file and preserve its atime and mtime
> > touch -r: touch a file and use a ref file's time instead of current time
>
> was there some discussion for this solution. I came to the same conclusion but cannot test it right now.

now that there is renewed activity in eCryptfs (thanks, btw). Can we
please consider this patch for a next cycle?

Thanks.

Best
Bert

>
> Thanks
> Bert
>
> >
> > In fs/attr.c notify_change(), atime and mtime is truncated by timestamp_truncate(),
> > ecryptfs gets wrong s_time_gran (10^9 instead of original fs time granularity) and
> > truncates a/mtime to whole second. Setting s_time_gran when mounting ecryptfs
> >   solves the issue.
> >
> > Signed-off-by: Frank Hsiao 蕭法宣 <[email protected]>
> >
> > diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
> > index b2f6a1937d239..19dbe9d1187e1 100644
> > --- a/fs/ecryptfs/main.c
> > +++ b/fs/ecryptfs/main.c
> > @@ -567,6 +567,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type
> >   *fs_type, int flags
> >       s->s_blocksize = path.dentry->d_sb->s_blocksize;
> >       s->s_magic = ECRYPTFS_SUPER_MAGIC;
> >       s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
> > +     s->s_time_gran = path.dentry->d_sb->s_time_gran;
> >
> >       rc = -EINVAL;
> >       if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {