Re: [PATCH 2/2] vfs: dedupe should return EPERM if permission is not granted

[Mark Fasheh <mfasheh@suse.de>]

On Thu, May 17, 2018 at 01:15:51AM -0400, Zygo Blaxell wrote:
> On Sun, May 13, 2018 at 11:26:39AM -0700, Darrick J. Wong wrote:
> > On Sun, May 13, 2018 at 06:21:52PM +0000, Mark Fasheh wrote:
> > > On Fri, May 11, 2018 at 05:06:34PM -0700, Darrick J. Wong wrote:
> > > > On Fri, May 11, 2018 at 12:26:51PM -0700, Mark Fasheh wrote:
> > > > > Right now we return EINVAL if a process does not have permission to dedupe a
> > > > > file. This was an oversight on my part. EPERM gives a true description of
> > > > > the nature of our error, and EINVAL is already used for the case that the
> > > > > filesystem does not support dedupe.
> > > > > 
> > > > > Signed-off-by: Mark Fasheh <mfasheh@suse.de>
> > > > > ---
> > > > >  fs/read_write.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/fs/read_write.c b/fs/read_write.c
> > > > > index 77986a2e2a3b..8edef43a182c 100644
> > > > > --- a/fs/read_write.c
> > > > > +++ b/fs/read_write.c
> > > > > @@ -2038,7 +2038,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
> > > > >  			info->status = -EINVAL;
> > > > >  		} else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE) ||
> > > > >  			     uid_eq(current_fsuid(), dst->i_uid))) {
> > > > > -			info->status = -EINVAL;
> > > > > +			info->status = -EPERM;
> > > > 
> > > > Hmm, are we allowed to change this aspect of the kabi after the fact?
> > > > 
> > > > Granted, we're only trading one error code for another, but will the
> > > > existing users of this care?  xfs_io won't and I assume duperemove won't
> > > > either, but what about bees? :)
> > > 
> > > Yeah if you see my initial e-mail I check bees and also rust-btrfs. I think
> > > this is fine as we're simply expanding on an error code return. There's no
> > > magic behavior expected with respect to these error codes either.
> > 
> > Ok.  No objections from me, then.
> > 
> > Acked-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> For what it's worth, no objection from me either.  ;)
> 
> bees runs only with admin privilege and will never hit the modified line.

Awesome, thanks for the review Zygo.
	--Mark