Hello,

Currently there is no way for modules to define dynamically sized caches that 
shrink upon memory pressure. We need this for implementing Extended Attribute 
caches on ext2, ext3, and ReiserFS. Other caches could also make use of the 
same mechanism (e.g., nfsd's permission cache, dcache, icache, dqache).

I propose this patch, which adds the register_cache() and unregister_cache() 
functions. They allow to register a callback which is invoked on memory 
pressure. This callback shall then try to free some memory; the parameters 
and semantics are similar to the other shrink functions in mm/vmscan.c.


Regards,
Andreas.

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 Andreas Gruenbacher                                SuSE Linux AG
 mailto:agruen@suse.de                     Deutschherrnstr. 15-19
 http://www.suse.de/                   D-90429 Nuernberg, Germany