NFS: split cache creation and PipeFS registration

This precursor patch splits NFS cache creation and PipeFS registartion.
It's required for latter split of NFS DNS resolver cache creation per network
namespace context and PipeFS registration/unregistration on MOUNT/UMOUNT
events.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/cache_lib.c

@@ -120,7 +120,6 @@ int nfs_cache_register(struct cache_detail *cd)
 	mnt = rpc_get_mount();
 	if (IS_ERR(mnt))
 		return PTR_ERR(mnt);
-	sunrpc_init_cache_detail(cd);
 	ret = vfs_path_lookup(mnt->mnt_root, mnt, "/cache", 0, &path);
 	if (ret)
 		goto err;
@@ -129,7 +128,6 @@ int nfs_cache_register(struct cache_detail *cd)
 	if (!ret)
 		return ret;
 err:
-	sunrpc_destroy_cache_detail(cd);
 	rpc_put_mount();
 	return ret;
 }
@@ -141,3 +139,12 @@ void nfs_cache_unregister(struct cache_detail *cd)
 	rpc_put_mount();
 }
 
+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);
+}

fs/nfs/cache_lib.h

@@ -23,5 +23,7 @@ extern struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void);
 extern void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq);
 extern int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq);
 
+extern void nfs_cache_init(struct cache_detail *cd);
+extern void nfs_cache_destroy(struct cache_detail *cd);
 extern int nfs_cache_register(struct cache_detail *cd);
 extern void nfs_cache_unregister(struct cache_detail *cd);

fs/nfs/dns_resolve.c

@@ -361,12 +361,21 @@ ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
 
 int nfs_dns_resolver_init(void)
 {
-	return nfs_cache_register(&nfs_dns_resolve);
+	int err;
+
+	nfs_cache_init(&nfs_dns_resolve);
+	err = nfs_cache_register(&nfs_dns_resolve);
+	if (err) {
+		nfs_cache_destroy(&nfs_dns_resolve);
+		return err;
+	}
+	return 0;
 }
 
 void nfs_dns_resolver_destroy(void)
 {
 	nfs_cache_unregister(&nfs_dns_resolve);
+	nfs_cache_destroy(&nfs_dns_resolve);
 }
 
 #endif