Re: [BUG] grub-install fails on devices with high minor numbers

[Andrei Borzenkov]

06.11.2015 22:59, Tim Walberg пишет:
> On 11/06/2015 21:26 +0300, Andrei Borzenkov wrote:
> > >         06.11.2015 19:08, Tim Walberg ??????????:
> > >         >On some relatively large systems that are used for virtualization,
> > >         >often containing upwards of 100 virtual machines, we've started running
> > >         >into issues with GRUB not being able to install on a new virtual 
> > > machine
> > >         >(using the typical process of mounting all the VM file systems on the 
> > > host
> > >         >and running grub-install under chroot). We've tracked the issue down 
> > > to this
> > >         >code, which is clearly erroneous - device minor numbers have been more 
> > > than
> > >         >8 bits for quite some time now - in 
> > > grub-core/osdep/devmapper/getroot.c:
> > >         >
> > >         >     char *
> > >         >     grub_util_devmapper_part_to_disk (struct stat *st,
> > >         >                                   int *is_part, const char *path)
> > >         >     {
> > >         >       int major, minor;
> > >         >
> > >         >       if (grub_util_get_dm_node_linear_info (st->st_rdev,
> > >         >                                          &major, &minor, 0))
> > >         >         {
> > >         >           *is_part = 1;
> > >         >           return grub_find_device ("/dev",
> > >         >                                    (major << 8) | minor);         
> > > <<<<< --------- ERROR!
> > >         >         }
> > >         >       *is_part = 0;
> > >         >       return xstrdup (path);
> > >         >     }
> > >         >
> > >         >When we have enough device-mapper devices (including all their 
> > > partitions)
> > >         >on a host that the next newly-added set of devices ends up with minor 
> > > numbers
> > >         >outside the 8-bit range, this code fails, with the result that 
> > > grub-install
> > >         >can't find the devices that it needs to complete the install.
> > >         >
> > >         >There might be other places in the code where similar assumptions are 
> > > made.
> > >         >Someone more familiar with the code would probably be better for 
> > > tracking
> > >         >those down. But, this one at least needs to be fixed.
> > >         >
> > >         
> > >         
> > >         Does attached patch help?
>
> > >         From: Andrei Borzenkov <address@hidden>
> > >         Subject: [PATCH] devmapper/getroot: use makedev instead of direct shift
> > >         
> > >         Fixes device detection with large number of devices.
> > >         
> > >         Reported by Tim Wallberg <address@hidden>
> > >         
> > >         ---
> > >          grub-core/osdep/devmapper/getroot.c | 3 +--
> > >          1 file changed, 1 insertion(+), 2 deletions(-)
> > >         
> > >         diff --git a/grub-core/osdep/devmapper/getroot.c 
> > > b/grub-core/osdep/devmapper/getroot.c
> > >         index 0a77a04..64419f6 100644
> > >         --- a/grub-core/osdep/devmapper/getroot.c
> > >         +++ b/grub-core/osdep/devmapper/getroot.c
> > >         @@ -208,8 +208,7 @@ grub_util_devmapper_part_to_disk (struct stat *st,
> > >                                                  &major, &minor, 0))
> > >              {
> > >                *is_part = 1;
> > >         -      return grub_find_device ("/dev",
> > >         -                              (major << 8) | minor);
> > >         +      return grub_find_device ("/dev", makedev (major, minor));
> > >              }
> > >            *is_part = 0;
> > >            return xstrdup (path);
> > >         --
> > >         tg: (cd6d79c..) u/makedev (depends on: master)
>
> End of included message
>
>
> Yes, that appears to have resolved the issue. I was already testing essentially
> that patch on my own, but wasn't sure if there might be similar assumptions
> made elsewhere in the code.

As far as I can tell, other places used makedev() already. Committed. 
Thanks!