>From 36bdb502360461a8426821a37728aef3a3b8c738 Mon Sep 17 00:00:00 2001
From: Kirill A. Shutemov <kas@openvz.org>
Date: Mon, 20 Dec 2010 04:03:52 +0200
Subject: [PATCH] sunrpc: introduce get_rpc_pipefs()

Get rpc_pipefs mount point by path.

Signed-off-by: Kirill A. Shutemov <kas@openvz.org>
---
 include/linux/sunrpc/rpc_pipe_fs.h |    2 +
 net/sunrpc/rpc_pipe.c              |   51 ++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 0 deletions(-)

diff --git a/include/linux/sunrpc/rpc_pipe_fs.h b/include/linux/sunrpc/rpc_pipe_fs.h
index b09bfa5..922057c 100644
--- a/include/linux/sunrpc/rpc_pipe_fs.h
+++ b/include/linux/sunrpc/rpc_pipe_fs.h
@@ -46,6 +46,8 @@ RPC_I(struct inode *inode)
 
 extern struct vfsmount *init_rpc_pipefs;
 
+struct vfsmount *get_rpc_pipefs(const char *path);
+
 extern int rpc_queue_upcall(struct inode *, struct rpc_pipe_msg *);
 
 struct rpc_clnt;
diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index b1e299b..4e09a90 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -16,6 +16,9 @@
 #include <linux/namei.h>
 #include <linux/fsnotify.h>
 #include <linux/kernel.h>
+#include <linux/nsproxy.h>
+#include <linux/mnt_namespace.h>
+#include <linux/fs_struct.h>
 
 #include <asm/ioctls.h>
 #include <linux/fs.h>
@@ -931,6 +934,54 @@ static const struct super_operations s_ops = {
 
 #define RPCAUTH_GSSMAGIC 0x67596969
 
+static int check_rpc_pipefs(struct vfsmount *mnt, void *arg)
+{
+	struct vfsmount **rpcmount = arg;
+	struct path path = {
+		.mnt = mnt,
+		.dentry = mnt->mnt_root,
+	};
+
+	if (!mnt->mnt_sb)
+		return 0;
+	if (mnt->mnt_sb->s_magic != RPCAUTH_GSSMAGIC)
+		return 0;
+
+	if (!path_is_under(&path, &current->fs->root))
+		return 0;
+
+	*rpcmount = mntget(mnt);
+	return 1;
+}
+
+struct vfsmount *get_rpc_pipefs(const char *p)
+{
+	int error;
+	struct vfsmount *rpcmount = ERR_PTR(-EINVAL);
+	struct path path;
+
+	if (!p) {
+		iterate_mounts(check_rpc_pipefs, &rpcmount,
+				current->nsproxy->mnt_ns->root);
+
+		if (IS_ERR(rpcmount) && (current->nsproxy->mnt_ns ==
+					init_task.nsproxy->mnt_ns))
+			return mntget(init_rpc_pipefs);
+
+		return rpcmount;
+	}
+
+	error = kern_path(p, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
+	if (error)
+		return ERR_PTR(error);
+
+	check_rpc_pipefs(path.mnt, &rpcmount);
+	path_put(&path);
+
+	return rpcmount;
+}
+EXPORT_SYMBOL_GPL(get_rpc_pipefs);
+
 /*
  * We have a single directory with 1 node in it.
  */
-- 
1.7.3.4