FS-Cache: Add the FS-Cache cache backend API and documentation

Add the API for a generic facility (FS-Cache) by which caches may declare them
selves open for business, and may obtain work to be done from network
filesystems.  The header file is included by:

	#include <linux/fscache-cache.h>

Documentation for the API is also added to:

	Documentation/filesystems/caching/backend-api.txt

This API is not usable without the implementation of the utility functions
which will be added in further patches.

Signed-off-by: David Howells <[email protected]>
Acked-by: Steve Dickson <[email protected]>
Acked-by: Trond Myklebust <[email protected]>
Acked-by: Al Viro <[email protected]>
Tested-by: Daire Byrne <[email protected]>
2 files changed