NFS: simplify and clean cache library

This is a cleanup patch.
Such helpers like nfs_cache_init() and nfs_cache_destroy() are redundant,
because they are just a wrappers around sunrpc_init_cache_detail() and
sunrpc_destroy_cache_detail() respectively.
So let's remove them completely and move corresponding logic to
nfs_cache_register_net() and nfs_cache_unregister_net() respectively (since
they are called together anyway).

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfs/cache_lib.c b/fs/nfs/cache_lib.c
index 862a2f1..5f7b053 100644
--- a/fs/nfs/cache_lib.c
+++ b/fs/nfs/cache_lib.c
@@ -128,10 +128,13 @@
 	struct super_block *pipefs_sb;
 	int ret = 0;
 
+	sunrpc_init_cache_detail(cd);
 	pipefs_sb = rpc_get_sb_net(net);
 	if (pipefs_sb) {
 		ret = nfs_cache_register_sb(pipefs_sb, cd);
 		rpc_put_sb_net(net);
+		if (ret)
+			sunrpc_destroy_cache_detail(cd);
 	}
 	return ret;
 }
@@ -151,14 +154,5 @@
 		nfs_cache_unregister_sb(pipefs_sb, cd);
 		rpc_put_sb_net(net);
 	}
-}
-
-void nfs_cache_init(struct cache_detail *cd)
-{
-	sunrpc_init_cache_detail(cd);
-}
-
-void nfs_cache_destroy(struct cache_detail *cd)
-{
 	sunrpc_destroy_cache_detail(cd);
 }