Re: [PATCH v2 6/8] vfs: copy_file_range should update file timestamps

Amir Goldstein
2019-05-28T16:37:07Z

On Tue, May 28, 2019 at 7:30 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> On Sun, May 26, 2019 at 09:10:57AM +0300, Amir Goldstein wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> >
> > Timestamps are not updated right now, so programs looking for
> > timestamp updates for file modifications (like rsync) will not
> > detect that files have changed. We are also accessing the source
> > data when doing a copy (but not when cloning) so we need to update
> > atime on the source file as well.
> >
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> > fs/read_write.c | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/fs/read_write.c b/fs/read_write.c
> > index e16bcafc0da2..4b23a86aacd9 100644
> > --- a/fs/read_write.c
> > +++ b/fs/read_write.c
> > @@ -1576,6 +1576,16 @@ int generic_copy_file_range_prep(struct file *file_in, struct file *file_out)
> >
> > WARN_ON_ONCE(!inode_is_locked(file_inode(file_out)));
> >
> > + /* Update source timestamps, because we are accessing file data */
> > + file_accessed(file_in);
> > +
> > + /* Update destination timestamps, since we can alter file contents. */
> > + if (!(file_out->f_mode & FMODE_NOCMTIME)) {
> > + ret = file_update_time(file_out);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > /*
> > * Clear the security bits if the process is not being run by root.
> > * This keeps people from modifying setuid and setgid binaries.
>
> Should the file_update_time and file_remove_privs calls be factored into
> a separate small function to be called by generic_{copy,remap}_range_prep?
>

Ok. same helper could be called also after copy when inode is not locked
throughout the copy.

Thanks,
Amir.