fscache, cachefiles: Display stat of culling events

Add a stat counter of culling events whereby the cache backend culls a file
to make space (when asked by cachefilesd in this case) and display in
/proc/fs/fscache/stats.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
3 files changed