[Pvfs2-developers] patch: ncache.patch

[Bart Taylor]

This patch is a reimplementation of name cache based off tcache, and it now
bears a striking resemblance to the attribute cache.  There was a
significant API change, but that did not have an effect other than fixing
the calls already in place.  There are no changes to the wire protocol or
the storage format.  It also includes perf-counter support for monitoring.

The state machines have several changes to use the new API, but the
functionality stayed the same in most places.  Sys-readdir.sm and
sys-lookup.sm had some minor changes/additions to make ncache update
properly. Lookup-ncache.sm now only checks the cache for one segment of the
path at a time instead of the entire path at once.   The new ncache stores
individual path segments independently.

There were updates to pvfs2-client.c and pvfs2-client-core.c to accept the
new ncache options and deal with them appropriately. There were also
additions in upcall.h and pvfs2-proc.c.  Pvfs2-proc has a generalization of
one of the functions to be used for both attribute cache and name cache.

Tuning for ncache can be done with the proc files in
/proc/sys/pvfs2/ncache.  They mimic the acache options: hard-limit,
soft-limit, reclaim-percentage, and timeout-msecs.  The performace counters
also imitate acache and are located in /proc/sys/pvfs2/perf-counters/ncache.
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