[OpenAFS] freezes acessing /afs/.git

Troy Benjegerdes hozer@hozed.org
Sun, 10 Aug 2014 00:31:14 -0500

On Wed, Aug 06, 2014 at 10:45:56AM -0400, chas williams - CONTRACTOR wrote:
> On Wed, 6 Aug 2014 13:47:28 +0000
> Brandon Allbery <ballbery@sinenomine.net> wrote:
> > I'm not sure how to mitigate this, though. Even if you could add a
> > "dummy" AFSDB or SRV record to intercept this lookup, last night I
> > tripped over a similar issue when rebooting my Mac:
> > http://lpaste.net/108884 (partial trace, it took several minutes to give
> > up on querying for both AFSDB and SRV records for many names it
> > shouldn't have been trying to look up IMO --- wtf is Finder doing?!)
> > Given my normal usage on this machine, I may well just knock down
> > -dynroot.
> > 
> I started working on a patch to 'fix' this issue:
> http://gerrit.openafs.org/#change,8011
> But as pointed out in the comments, it's too specific and should be a
> more general mechanism.  Unfortunately, the preceding '.' is stripped
> from names before passing down to afsd for resolution so it wouldn't be
> possible to block /afs/.git without also blocking /afs/git
> Also, as was pointed out, negative caching would help as well.

This really needs some sort of testcase and regression tests. 

I keep randomly hitting this stuff and I just 'got used to' my machine 
(or maybe just a process) become unusable for awhile. It's the kind of
thing that someone tries AFS, and runs into this, and then never uses
it again.

Part of the problem is also applications that look for random files all
over the place

I think negative caching and maybe some sort of 'cell-configured' negative
cache file is going to be necessary.

Troy Benjegerdes                 'da hozer'                  hozer@hozed.org
7 elements      earth::water::air::fire::mind::spirit::soul        grid.coop

      Never pick a fight with someone who buys ink by the barrel,
         nor try buy a hacker who makes money by the megahash