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

Steve Dickson
2010-02-04T22:06:42Z

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..

Committed...

steved.