SUNRPC: Allow the cache_detail to specify alternative upcall mechanisms

For events that are rare, such as referral DNS lookups, it makes limited
sense to have a daemon constantly listening for upcalls on a channel. An
alternative in those cases might simply be to run the app that fills the
cache using call_usermodehelper_exec() and friends.

The following patch allows the cache_detail to specify alternative upcall
mechanisms for these particular cases.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index 3d1fad22185a..23ee25981a0c 100644
--- a/include/linux/sunrpc/cache.h
+++ b/include/linux/sunrpc/cache.h
@@ -70,9 +70,9 @@ struct cache_detail {
         char                    *name;
         void                    (*cache_put)(struct kref *);
 
-        void                    (*cache_request)(struct cache_detail *cd,
-                                                 struct cache_head *h,
-                                                 char **bpp, int *blen);
+        int                     (*cache_upcall)(struct cache_detail *,
+                                                struct cache_head *);
+
         int                     (*cache_parse)(struct cache_detail *,
                                                char *buf, int len);
 
@@ -135,6 +135,13 @@ extern struct cache_head *
 sunrpc_cache_update(struct cache_detail *detail,
                     struct cache_head *new, struct cache_head *old, int hash);
 
+extern int
+sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h,
+                void (*cache_request)(struct cache_detail *,
+                                      struct cache_head *,
+                                      char **,
+                                      int *));
+
 
 extern void cache_clean_deferred(void *owner);