Re: [PATCH 24/25] xfs: support returning partial reflink results

Darrick J. Wong
2018-10-15T15:49:59Z

On Mon, Oct 15, 2018 at 10:05:36AM +1100, Dave Chinner wrote:
> On Sun, Oct 14, 2018 at 10:35:46AM -0700, Christoph Hellwig wrote:
> > On Fri, Oct 12, 2018 at 05:08:32PM -0700, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > >
> > > Back when the XFS reflink code only supported clone_file_range, we were
> > > only able to return zero or negative error codes to userspace. However,
> > > now that copy_file_range (which returns bytes copied) can use XFS'
> > > clone_file_range, we have the opportunity to return partial results.
> > > For example, if userspace sends a 1GB clone request and we run out of
> > > space halfway through, we at least can tell userspace that we completed
> > > 512M of that request like a regular write.
> > >
> > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > > ---
> > > fs/xfs/xfs_file.c | 5 +----
> > > fs/xfs/xfs_reflink.c | 20 +++++++++++++++-----
> > > fs/xfs/xfs_reflink.h | 2 +-
> > > 3 files changed, 17 insertions(+), 10 deletions(-)
> > >
> > >
> > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > > index bc9e94bcb7a3..b2b15b8dc4a1 100644
> > > --- a/fs/xfs/xfs_file.c
> > > +++ b/fs/xfs/xfs_file.c
> > > @@ -928,14 +928,11 @@ xfs_file_remap_range(
> > > loff_t len,
> > > unsigned int remap_flags)
> > > {
> > > - int ret;
> > > -
> > > if (!remap_check_flags(remap_flags, RFR_SAME_DATA))
> > > return -EINVAL;
> > >
> > > - ret = xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
> > > + return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
> > > len, remap_flags);
> >
> > Is there any reason not to merge xfs_file_remap_range and
> > xfs_reflink_remap_range at this point?
>
> Yeah, that seems like a good idea to me - pulling all the
> vfs/generic code interactions back up into xfs_file.c would match
> how the rest of the file operations are layered w.r.t. external and
> internal XFS code...

Yeah, ditto ocfs2. I'll look into throwing a few more refactors onto
the end of this series... 8-D

--D

> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@fromorbit.com