Re: crash zfs_clone_range()

On 11/14/23, Rick Macklem <rick.macklem@gmail.com> wrote:
> On Tue, Nov 14, 2023 at 10:46 AM Alexander Motin <mav@freebsd.org> wrote:
>>
>> On 14.11.2023 12:44, Alexander Motin wrote:
>> > On 14.11.2023 12:39, Mateusz Guzik wrote:
>> >> One of the vnodes is probably not zfs, I suspect this will do it
>> >> (untested):
>> >>
>> >> diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
>> >> b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
>> >> index 107cd69c756c..e799a7091b8e 100644
>> >> --- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
>> >> +++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
>> >> @@ -6270,6 +6270,11 @@ zfs_freebsd_copy_file_range(struct
>> >> vop_copy_file_range_args *ap)
>> >>                          goto bad_write_fallback;
>> >>                  }
>> >>          }
>> >> +
>> >> +       if (invp->v_mount->mnt_vfc != outvp->v_mount->mnt_vfc) {
>> >> +               goto bad_write_fallback;
>> >> +       }
>> >> +
>> >>          if (invp == outvp) {
>> >>                  if (vn_lock(outvp, LK_EXCLUSIVE) != 0) {
>> >>                          goto bad_write_fallback;
>> >>
>> >
>> > vn_copy_file_range() verifies for that:
>> >
>> >          /*
>> >           * If the two vnodes are for the same file system type, call
>> >           * VOP_COPY_FILE_RANGE(), otherwise call
>> > vn_generic_copy_file_range()
>> >           * which can handle copies across multiple file system types.
>> >           */
>> >          *lenp = len;
>> >          if (inmp == outmp || strcmp(inmp->mnt_vfc->vfc_name,
>> >              outmp->mnt_vfc->vfc_name) == 0)
>> >                  error = VOP_COPY_FILE_RANGE(invp, inoffp, outvp,
>> > outoffp,
>> >                      lenp, flags, incred, outcred, fsize_td);
>> >          else
>> >                  error = vn_generic_copy_file_range(invp, inoffp,
>> > outvp,
>> >                      outoffp, lenp, flags, incred, outcred, fsize_td);
>>
>> Thinking again, what happen if there are two nullfs mounts on top of two
>> different file systems, one of which is indeed not ZFS?  Do we need to
>> add those checks to all ZFS, NFS and FUSE, implementing
>> VOP_COPY_FILE_RANGE, or it is responsibility of nullfs or VFS?
> Although it would be nice to do the check before the VOP call, I don't
> see an easy way to do that.
>
> It looks like the simple solution is to add a check in each of the
> VOP_COPY_FILE_RANGE() calls, such as mjg@ has proposed
> for ZFS. At this point there is only the three and I can easily do the
> NFS one.
>

All filesystems except for zfs are already covered because they check
for mismatched mount.

-- 
Mateusz Guzik <mjguzik gmail.com>