[Ocfs2-devel] [PATCH 24/25] xfs: support returning partial reflink results

[Dave Chinner]

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 at 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 at 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...

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com