On Mon, Feb 05, 2018 at 06:07:13PM +0100, Martin Wilck wrote:
> On Mon, 2018-02-05 at 16:46 +0100, Julian Andres Klode wrote:
> > On Mon, Feb 05, 2018 at 04:12:00PM +0100, Martin Wilck wrote:
> > >
> > > Can we agree on the following:
> > >
> > > 1 if realpath (filename) results in error, abort
> >
> > OK
> >
> >
> > > 2 if realpath(lo_name) results in ENODEV and filename matches
> > > lo_name,
> > > remove loop device
> > > 3 if realpath(lo_name) results in another error code, skip it
> > > 4 remove if realpath(filename) matches realpath(lo_name)
> >
> >
> > This seems like a lot of ifs. It might be easier to just path if
> > realpath(path) fails (as realpath(1) does), something like:
> >
> >
> > char *loopname = loopinfo.lo_name;
> > if (realpath(loopinfo.lo_name, rloopfilename) != NULL)
> > loopname = rloopfilename;
> >
> > if (0 == strcmp(filename, loopinfo.lo_name) ||my
> 0 == strcmp(rfilename, loopname))) {
> > found = realpath(path, NULL);
> > break;
> > }
> >
> >
> > That should solve all problems and produce useful results with not
> > a lot of logic.
>
> I've reproduced your issue. I can see that the current behavior is
> wrong.
>
> This may be paranoid, but I really want to avoid false positives -
> kpartx removing mappings it isn't supposed to remove. Therefore I'd
> like to avoid compare by "filename" and "loopname". I think it's
> possible.
>
> IMO it would be better to have kpartx use the realpath while *creating*
> the partition mapping already:
>
> --- a/kpartx/kpartx.c
> +++ b/kpartx/kpartx.c
> @@ -341,7 +341,7 @@ main(int argc, char **argv){
> if (!loopdev) {
> loopdev = find_unused_loop_device();
>
> - if (set_loop(loopdev, device, 0, &ro)) {
> + if (set_loop(loopdev, rpath, 0, &ro)) {
> fprintf(stderr, "can't set up loop\n");
> exit (1);
> }
>
>
> That would make sure that kpartx can delete loop devices created by
> itself, which is what we want. IMO it's sufficient to solve your issue.
I was about to suggest that, but did not do it, as it's kind of weird. You
add /a/b/c.img (pointing to /x/y/z.img) and losetup then shows you /x/y/z.img
- I fear this might break some stuff that checks whether the binding was
actually created (or checks which loop device it was created at).
--
debian developer - deb.li/jak | jak-linux.org - free software dev
ubuntu core developer i speak de, en
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
