Re: [PATCH 1/2] vfs: vfs_dedupe_file_range() doesn't return EOPNOTSUPP

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Thu, Nov 08, 2018 at 03:03:49PM -0800, Darrick J. Wong wrote:
> On Fri, Nov 09, 2018 at 09:19:08AM +1100, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> > 
> > It returns EINVAL when the operation is not supported by the
> > filesystem. Fix it to return EOPNOTSUPP to be consistent with
> > the man page and clone_file_range().
> > 
> > Clean up the inconsistent error return handling while I'm there.
> > (I know, lipstick on a pig, but every little bit helps...)
> > 
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> 
> Looks ok, would rather just shred this ioctl and make a better one. :P
> 
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> --D
> 
> > ---
> >  fs/read_write.c | 15 +++++++--------
> >  1 file changed, 7 insertions(+), 8 deletions(-)
> > 
> > diff --git a/fs/read_write.c b/fs/read_write.c
> > index bfcb4ced5664..aa43224bcec6 100644
> > --- a/fs/read_write.c
> > +++ b/fs/read_write.c
> > @@ -2094,17 +2094,18 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
> >  	off = same->src_offset;
> >  	len = same->src_length;
> >  
> > -	ret = -EISDIR;
> > +	if (!file->f_op->remap_file_range)
> > +		return -EOPNOTSUPP;

Minor downside: this causes regressions in generic/158 because
directories and device files don't have a ->remap_file_range
implementation.  I think it can be solved by moving this check after the
!S_ISREG check below.

--D

> > +
> >  	if (S_ISDIR(src->i_mode))
> > -		goto out;
> > +		return -EISDIR;
> >  
> > -	ret = -EINVAL;
> >  	if (!S_ISREG(src->i_mode))
> > -		goto out;
> > +		return -EINVAL;
> >  
> >  	ret = remap_verify_area(file, off, len, false);
> >  	if (ret < 0)
> > -		goto out;
> > +		return ret;
> >  	ret = 0;
> >  
> >  	if (off + len > i_size_read(src))
> > @@ -2147,10 +2148,8 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
> >  		fdput(dst_fd);
> >  next_loop:
> >  		if (fatal_signal_pending(current))
> > -			goto out;
> > +			break;
> >  	}
> > -
> > -out:
> >  	return ret;
> >  }
> >  EXPORT_SYMBOL(vfs_dedupe_file_range);
> > -- 
> > 2.19.1
> >