Re: [PATCH 1/2] nfsd: fix version-setting regression on old kernels

J. Bruce Fields
2010-02-04T22:15:52Z

On Thu, Feb 04, 2010 at 05:06:34PM -0500, Steve Dickson wrote:
>
>
> On 02/04/2010 04:47 PM, J. Bruce Fields wrote:
> > On Thu, Feb 04, 2010 at 04:37:52PM -0500, Steve Dickson wrote:
> >>
> >>
> >> On 01/27/2010 05:26 PM, J. Bruce Fields wrote:
> >>> /proc/fs/nfsd/versions was extended to allow turning on/off minor
> >>> versions by echoing "+4.1" or "-4.1" to /proc/fs/nsfd/versions.
> >>>
> >>> Unfortunately, pre-2.6.30 kernels just stop parsing at first non-digit,
> >>> so "-4.1" is interpreted as "-4". If new nfs-utils (on old kernel)
> >>> writes "+2", "+3", "+4", then "-4.1", result therefore is to turn off
> >>> 4.1.
> >>>
> >>> Given that historical behavior, it may have been a mistake to extend the
> >>> interface the way we did; but at this point we're probably stuck with
> >>> it. So, just reverse the order we write versions in.
> >>>
> >>> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
> >>> ---
> >>> utils/nfsd/nfssvc.c | 10 +++++-----
> >>> 1 files changed, 5 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/utils/nfsd/nfssvc.c b/utils/nfsd/nfssvc.c
> >>> index b8028bb..7bbbaba 100644
> >>> --- a/utils/nfsd/nfssvc.c
> >>> +++ b/utils/nfsd/nfssvc.c
> >>> @@ -238,17 +238,17 @@ nfssvc_setvers(unsigned int ctlbits, int minorvers4)
> >>> if (fd < 0)
> >>> return;
> >>>
> >>> + n = minorvers4 >= 0 ? minorvers4 : -minorvers4;
> >>> + if (n >= NFSD_MINMINORVERS4 && n <= NFSD_MAXMINORVERS4)
> >>> + off += snprintf(ptr+off, sizeof(buf) - off, "%c4.%d",
> >> There needs to be a space between the %d and ".
> >>
> >> But more importantly what problem is the patch fixing?? I've tested this
> >> on a 2.6.29 and 2.6.31 as well as a 2.6.33 kernel and I see no different
> >> in how the versions are ordered.
> >
> > See the patch description. A test case:
> >
> > - boot 2.6.29
> > - run 'nfsd -N4.1'
> > - try to mount v4.0.
> >
> > See also https://bugzilla.redhat.com/show_bug.cgi?id=512377.
> Ah... I see it now... for some reason I thought this was fixed already..

I think you worked around it in fedora by dropping the -N4.1 from the
initscripts temporarily?

Thanks for catching the missing space, obviously I hadn't tested this
version properly!

--b.