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From: Dave Chinner <david@fromorbit.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	Olga Kornievskaia <olga.kornievskaia@gmail.com>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org
Subject: Re: [PATCH 07/11] vfs: copy_file_range should update file timestamps
Date: Tue, 4 Dec 2018 10:19:21 +1100
Message-ID: <20181203231921.GJ6311@dastard> (raw)
In-Reply-To: <CAOQ4uxiCi9qJ15J=L6fNjuLGykQm5CDuJ-=Y=TwTP5c=jx-_fA@mail.gmail.com>

On Mon, Dec 03, 2018 at 12:47:39PM +0200, Amir Goldstein wrote:
> On Mon, Dec 3, 2018 at 10:34 AM Dave Chinner <david@fromorbit.com> 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>
> > ---
> >  fs/read_write.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/fs/read_write.c b/fs/read_write.c
> > index 3b101183ea19..3288db1d5f21 100644
> > --- a/fs/read_write.c
> > +++ b/fs/read_write.c
> > @@ -1576,6 +1576,16 @@ static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in,
> >  {
> >         ssize_t ret;
> >
> > +       /* 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;
> > +       }
> > +
> 
> If there is a consistency about who is responsible of calling file_accessed()
> and file_update_time() it eludes me. grep tells me that they are mostly
> handled by filesystem code or generic helpers called by filesystem code
> and not in the vfs helpers.

This isn't the "vfs helper" - this is the code that executes a data
copy. We have to do these timestamp updates regardless of the copy
mechanism used so it makes no real sense to force every
implementation to do it, and then also have to ensure the generic
fallback does it as well. Do it once for everyone, then nobody else
needs to care about it.

> FMODE_NOCMTIME seems like an xfs specific flag (for DMAPI?), which

It's a generic VFS flag that originally only XFS used. We check it
in places where data IO to XFS files might be done. Given that we
have vfs functions doing write on behalf of XFS filesystems (such as
remap_file_range() and copy_file_range() the timestamp updates need
to check this flag.

> most generic callers of file_update_time() completely ignore.

Because most cases don't get called from a context that can have
FMODE_NOCMTIME set. If more filesystems start to use FMODE_NOCMTIME
then it will have to be more widely checked.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  parent reply index

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-03  8:34 [PATCH 0/11] fs: fixes for major copy_file_range() issues Dave Chinner
2018-12-03  8:34 ` [PATCH 01/11] vfs: copy_file_range source range over EOF should fail Dave Chinner
2018-12-03 12:46   ` Amir Goldstein
2018-12-04 15:13     ` Christoph Hellwig
2018-12-04 21:29       ` Dave Chinner
2018-12-04 21:47         ` Olga Kornievskaia
2018-12-04 22:31           ` Dave Chinner
2018-12-05 16:51             ` bfields
2019-05-20  9:10             ` Amir Goldstein
2019-05-20 13:12               ` Olga Kornievskaia
2019-05-20 13:36                 ` Amir Goldstein
2019-05-20 13:58                   ` Olga Kornievskaia
2019-05-20 14:02                     ` Amir Goldstein
2018-12-05 14:12         ` Christoph Hellwig
2018-12-05 21:08           ` Dave Chinner
2018-12-05 21:30             ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 02/11] vfs: introduce generic_copy_file_range() Dave Chinner
2018-12-03 10:03   ` Amir Goldstein
2018-12-03 23:00     ` Dave Chinner
2018-12-04 15:14   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 03/11] vfs: no fallback for ->copy_file_range Dave Chinner
2018-12-03 10:22   ` Amir Goldstein
2018-12-03 23:02     ` Dave Chinner
2018-12-06  4:16       ` Amir Goldstein
2018-12-06 21:30         ` Dave Chinner
2018-12-07  5:38           ` Amir Goldstein
2018-12-03 18:23   ` Anna Schumaker
2018-12-04 15:16   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 04/11] vfs: add missing checks to copy_file_range Dave Chinner
2018-12-03 12:42   ` Amir Goldstein
2018-12-03 19:04   ` Darrick J. Wong
2018-12-03 21:33   ` Olga Kornievskaia
2018-12-03 23:04     ` Dave Chinner
2018-12-04 15:18   ` Christoph Hellwig
2018-12-12 11:31   ` Luis Henriques
2018-12-12 16:42     ` Darrick J. Wong
2018-12-12 18:55     ` Olga Kornievskaia
2018-12-12 19:42       ` Matthew Wilcox
2018-12-12 20:22         ` Olga Kornievskaia
2018-12-13 10:29           ` Luis Henriques
2018-12-03  8:34 ` [PATCH 05/11] vfs: use inode_permission in copy_file_range() Dave Chinner
2018-12-03 12:47   ` Amir Goldstein
2018-12-03 18:18   ` Darrick J. Wong
2018-12-03 23:55     ` Dave Chinner
2018-12-05 17:28       ` bfields
2018-12-03 18:53   ` Eric Biggers
2018-12-04 15:19   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 06/11] vfs: copy_file_range needs to strip setuid bits Dave Chinner
2018-12-03 12:51   ` Amir Goldstein
2018-12-04 15:21   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 07/11] vfs: copy_file_range should update file timestamps Dave Chinner
2018-12-03 10:47   ` Amir Goldstein
2018-12-03 17:33     ` Olga Kornievskaia
2018-12-03 18:22       ` Darrick J. Wong
2018-12-03 23:19     ` Dave Chinner [this message]
2018-12-04 15:24   ` Christoph Hellwig
2018-12-03  8:34 ` [PATCH 08/11] vfs: push EXDEV check down into ->remap_file_range Dave Chinner
2018-12-03 11:04   ` Amir Goldstein
2018-12-03 19:11     ` Darrick J. Wong
2018-12-03 23:37       ` Dave Chinner
2018-12-03 23:58         ` Darrick J. Wong
2018-12-04  9:17           ` Amir Goldstein
2018-12-03 23:34     ` Dave Chinner
2018-12-03 18:24   ` Darrick J. Wong
2018-12-04  8:18   ` Olga Kornievskaia
2018-12-03  8:34 ` [PATCH 09/11] vfs: push copy_file_ranges -EXDEV checks down Dave Chinner
2018-12-03 12:36   ` Amir Goldstein
2018-12-03 17:58   ` Olga Kornievskaia
2018-12-03 18:53   ` Anna Schumaker
2018-12-03 19:27     ` Olga Kornievskaia
2018-12-03 23:40     ` Dave Chinner
2018-12-04 15:43   ` Christoph Hellwig
2018-12-04 22:18     ` Dave Chinner
2018-12-04 23:33       ` Olga Kornievskaia
2018-12-05 14:09       ` Christoph Hellwig
2018-12-05 17:01         ` Olga Kornievskaia
2018-12-03  8:34 ` [PATCH 10/11] vfs: allow generic_copy_file_range to copy across devices Dave Chinner
2018-12-03 12:54   ` Amir Goldstein
2018-12-03  8:34 ` [PATCH 11/11] ovl: allow cross-device copy_file_range calls Dave Chinner
2018-12-03 12:55   ` Amir Goldstein
2018-12-03  8:39 ` [PATCH 12/11] man-pages: copy_file_range updates Dave Chinner
2018-12-03 13:05   ` Amir Goldstein
2019-05-21  5:52   ` Amir Goldstein

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