[OpenAFS] cm fails to invalidate cache for deleted files in volume root w/ fakestat

[Stephan Wiesand]

On Mon, 14 Apr 2008, Rainer Toebbicke wrote:

> We ran into this over a year ago and fixed it, but I must have forgotten to 
> submit the fix.
>
> It is actually the detection of a "cell" in the mount point string which 
> triggers the (loosely consistent) fakestat handling - it's treated like a 
> foreign cell and the mount point is never "completely evaluated", i.e. 
> logically replaced by the root directory of the volume in question. As a 
> result, callbacks are ignored, as they go against the directory and not the 
> mount point.
>
> The attached patch takes care of that.

Thanks a lot for the patch, and to Derrick for pulling it into 1.4.7.
This will allow us to enable fakestat again on certain clients.

- Stephan

> (Bcc'ed openafs-bugs)
>
>
> Stephan Wiesand schrieb:
>> If a client runs with the -fakestat[-all] option, and has a file cached 
>> that resides in the root directory of a volume affected by fakestat, it 
>> fails to invalidate its cache for this file when it's deleted:
>> 
>> ClientA: touch x
>> ClientB: ls -l x
>> ... 0 Apr 10 13:10 x
>> 
>> ClientA: echo a >> x
>> ClientB: ls -l x; cat x
>> ... 2 Apr 10 13:11 x
>> a
>> 
>> ClientA: rm x
>> ClientB: ls -l x; cat x
>> ... 2 Apr 10 13:11 x                   (!)
>> a                                      (!)
>> 
>> ClientA: echo b > x
>> ClientB: ls -l x; cat x
>> ... 2 Apr 10 13:11 x                   (!)
>> a                                      (!)
>> 
>> ClientB: fs flushv; ls -l x; cat x
>> ... 2 Apr 10 13:12 x
>> b
>> 
>> 
>> I guess it's the same issue reported by Jack Neely on March 17th. We're not 
>> running with -fakestat-all, just -fakestat. The problem struck when mount 
>> points for local volumes were accidentally created with the -cell option. 
>> We can reproduce the problem with local and foreign volumes. Turning off 
>> fakestat eliminates it reliably.
>> 
>> We observe this with various Linux clients. OpenAFS 1.4.6 or 1.4.7pre3, 
>> SL3/4/5, 32/64-bit.
>> 
>> An SL3 client still running 1.2.13 does not exhibit this problem.
>> 
>> Bcc to openafs-bugs.
>> 
>
>
>

-- 
Stephan Wiesand
   DESY - DV -
   Platanenallee 6
   15738 Zeuthen, Germany