Re: [PATCH 0/2] autofs: fix two related bugs with lookup + expired yp maps

[Jeff Mahoney <jeffm@suse.com>]

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On 5/5/16 6:21 AM, Ian Kent wrote:
> On Thu, 2016-05-05 at 16:35 +0800, Ian Kent wrote:
>> On Wed, 2016-05-04 at 20:03 -0400, jeffm@suse.com wrote:
>>> From: Jeff Mahoney <jeffm@suse.com>
>>>
>>> Hi Ian -
>>>
>>> We recently encountered an issue where a client would all of a sudden
>>> start returning ELOOP for anything involving crossing an autofs mount.
>>> We tracked it down to two bugs, one which obscured the other.  The
>>> first
>>> is that we were not properly updating the map age for yp maps when we
>>> retry
>>> the lookup with dots instead of underscores.  The second is that it is
>>> possible under several situations to return success when there was a
>>> failure in lookup_nss_mount.  In this particular case, it was the only
>>> map in the list and since the age wasn't update, it was skipped.  Then
>>> we exit the while loop with ret == 0, ultimately returning success to
>>> the caller.  Autofs would tell the kernel it succeeded, the kernel
>>> would
>>> retry the lookup, and we'd loop until we hit the kernel loop limit
>>> (40).
>>>
>>> These two patches fix each of the issues.
>>
>> OK, that sounds good.
>>
>> I'll have a look at the code to make sure I understand what's going on
>> before adding these to the list of patches I have.
>>
>> That list is getting a bit large now so I'll likely be committing them
>> soonish but I can't say yet when I'll release 5.1.2.
>>
>> Up until now I thought that the source of the ELOOP returns that some
>> people have seen were due to incorrect returns of in kernel mounted
>> checks where mounts were present in other namespaces.
>>
>> My most recent attempt at resolving that had a positive response from a
>> tester here on the list but another tester experienced file system
>> corruption. I'm totally at mystified by this so I'm a bit stuck at the
>> moment. 
> 
> When importing these I've made a couple of changes I hope you will be ok with.
> The content of the patches remains the same (assuming I have no other questions
> when I properly review them).
> 
> Due to my convention of trying to always have the patch title the same as the
> patch name I had to change the first patch.
> 
> I changed the patch name (and title with "-" changed to " ") to:
> autofs-5.1.1-fix-yp-map-age-not-updated-during-map-lookup.patch
> 
> The description remains the same and I think still conveys the intent of the
> change.
> 
> I changed only autofs: to autofs-5.1.1 in the second patch.
> 
> Finally I assume your ok with me adding your "Signed-off-by:" to both patches,
> along with mine.

Yep, sounds good to me.

Thanks,

-Jeff


-- 
Jeff Mahoney
SUSE Labs


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