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

[Ian Kent <raven@themaw.net>]

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.

> 
> > 
> > Thanks,
> > 
> > -Jeff
> > 
> > Jeff Mahoney (2):
> >   autofs: fix yp map age not updated in s/_/./g case
> >   autofs: properly handle errors in lookup_nss_mount
> > 
> >  daemon/lookup.c     |  5 ++++-
> >  modules/lookup_yp.c | 17 ++++++++---------
> >  2 files changed, 12 insertions(+), 10 deletions(-)
> > 
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