[PATCH] new helpers - collect_mounts() and release_collected_mounts()

Get a snapshot of a subtree, creating private clones of vfsmounts
for all its components and release such snapshot resp.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/pnode.h b/fs/pnode.h
index d45bd8e..f249be2 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -22,6 +22,7 @@
 #define CL_COPY_ALL 		0x04
 #define CL_MAKE_SHARED 		0x08
 #define CL_PROPAGATION 		0x10
+#define CL_PRIVATE 		0x20
 
 static inline void set_mnt_shared(struct vfsmount *mnt)
 {