Re: [PATCH] Reinstantiating stale inodes

[Steve Dickson <SteveD@redhat.com>]

Hi Olaf,

Olaf Kirch wrote:

>On Fri, Apr 23, 2004 at 10:15:35AM -0400, Steve Dickson wrote:
>  
>
>>Here is a 2.4 patch that will reinstantiate an inode
>>when a ESTALE error is returned on a getattr. When
>>the error occurs, a lookup is immediately issued
>>to get a new fh.
>>    
>>
>
>Brrr. Are you sure this is such a good idea?  It will have all sorts of
>bad side effects. 
>
This is why I'm asking.... In the beginning I also thought this ideas was
a bit brain dead ...  but after a bunch of trials and tribulations and not
being able to do it any other way that didn't effect normal
traffic... it kinda grew on me... :)

>For instance, you may be writing a file named "foo".
>Someone else replaces foo with their copy (mv foo-new foo) and your file
>handle becomes stale.
>  
>
True... but the write or commit will still fail with ESTALE. This
patch only effects getattrs (or stat()s). I guess my subject line
was a bit miss leading...

>If you issue a lookup immediately, you will continue writing, but
>now your writes go to the new file and produce garbage.
>  
>
Here are the tests I ran:

client: writes 100m file called foo
server: rm foo
client: the write or commit failed with ESTALE

client: writes 100m file called foo
server: renames foo to foo.old and immediately creates foo
client: failed with ESTALE

client: writes 100m file called foo
Same client: rm foo
client: finishes writing then the file is removed

client: writes 100m file called foo
Same client: renames foo to foo.old and immediately creates foo
client: both write to foo and foo.old complete and sum -r shows
        they are identical

Again only getattrs will be followed up with lookups..

>At a minimum, the lookup should occur at file open, and only if
>there are no other users of the inode.
>  
>
Unfortunately, in this particular case, there were no opens...


SteveD.


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