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, 14 insertions, 2 deletions

diff --git a/fs/nfsd/nfs4idmap.c b/fs/nfsd/nfs4idmap.c
index e9012ad36ac0..cdfa86fa1471 100644
--- a/fs/nfsd/nfs4idmap.c
+++ b/fs/nfsd/nfs4idmap.c
@@ -146,6 +146,12 @@ idtoname_request(struct cache_detail *cd, struct cache_head *ch, char **bpp,
 }
 
 static int
+idtoname_upcall(struct cache_detail *cd, struct cache_head *ch)
+{
+        return sunrpc_cache_pipe_upcall(cd, ch, idtoname_request);
+}
+
+static int
 idtoname_match(struct cache_head *ca, struct cache_head *cb)
 {
         struct ent *a = container_of(ca, struct ent, h);
@@ -192,7 +198,7 @@ static struct cache_detail idtoname_cache = {
         .hash_table     = idtoname_table,
         .name           = "nfs4.idtoname",
         .cache_put      = ent_put,
-        .cache_request  = idtoname_request,
+        .cache_upcall   = idtoname_upcall,
         .cache_parse    = idtoname_parse,
         .cache_show     = idtoname_show,
         .warn_no_listener = warn_no_idmapd,
@@ -325,6 +331,12 @@ nametoid_request(struct cache_detail *cd, struct cache_head *ch, char **bpp,
 }
 
 static int
+nametoid_upcall(struct cache_detail *cd, struct cache_head *ch)
+{
+        return sunrpc_cache_pipe_upcall(cd, ch, nametoid_request);
+}
+
+static int
 nametoid_match(struct cache_head *ca, struct cache_head *cb)
 {
         struct ent *a = container_of(ca, struct ent, h);
@@ -363,7 +375,7 @@ static struct cache_detail nametoid_cache = {
         .hash_table     = nametoid_table,
         .name           = "nfs4.nametoid",
         .cache_put      = ent_put,
-        .cache_request  = nametoid_request,
+        .cache_upcall   = nametoid_upcall,
         .cache_parse    = nametoid_parse,
         .cache_show     = nametoid_show,
         .warn_no_listener = warn_no_idmapd,