FS-Cache: Add cache tag handling

Implement two features of FS-Cache:

 (1) The ability to request and release cache tags - names by which a cache may
     be known to a netfs, and thus selected for use.

 (2) An internal function by which a cache is selected by consulting the netfs,
     if the netfs wishes to be consulted.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 4113af8d1660..0a2069afa417 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -28,6 +28,15 @@
 #define FSCACHE_MAX_THREADS     32
 
 /*
+ * fsc-cache.c
+ */
+extern struct list_head fscache_cache_list;
+extern struct rw_semaphore fscache_addremove_sem;
+
+extern struct fscache_cache *fscache_select_cache_for_object(
+        struct fscache_cookie *);
+
+/*
  * fsc-fsdef.c
  */
 extern struct fscache_cookie fscache_fsdef_index;
@@ -168,6 +177,17 @@ extern const struct file_operations fscache_stats_fops;
 #define fscache_stat(stat) do {} while (0)
 #endif
 
+/*
+ * raise an event on an object
+ * - if the event is not masked for that object, then the object is
+ *   queued for attention by the thread pool.
+ */
+static inline void fscache_raise_event(struct fscache_object *object,
+                                       unsigned event)
+{
+        BUG();  // TODO
+}
+
 /*****************************************************************************/
 /*
  * debug tracing