[Linux-cachefs] fscache 2 GB file size limitation

[Eric Becker]

I've attempted to benchmark cachefs on an ubuntu 10.04 machine using 
ext4 on / as the filesystem cache.  I've been reading files into memory 
using cat and redirecting the output to /dev/null.  This seems to 
utilize the cache just fine if the file is <= 2 GB.  However, if the 
file is anything over 2 GB, the cache is completely unused.  I'll clear 
stop cachefilesd, clear out the file system cache (rm -f -r 
/var/cache/fscache/*), and then restart cachefilesd to make sure there's 
nothing in it.  Then if I cat a 2.1 GB file to /dev/null du shows the 
/var/cache/fscache dir as a few KB large.  If I do the same thing with a 
2 GB file du shows the cache as using 2 GB of disk space.

Is this expected behavior or is there something I'm overlooking?

-Eric