vfs: take /proc/*/mounts and friends to fs/proc_namespace.c

rationale: that stuff is far tighter bound to fs/namespace.c than to
the guts of procfs proper.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/mount.h b/fs/mount.h
index e094c86..c6e99e0 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -1,4 +1,14 @@
 #include <linux/mount.h>
+#include <linux/seq_file.h>
+#include <linux/poll.h>
+
+struct mnt_namespace {
+	atomic_t		count;
+	struct vfsmount *	root;
+	struct list_head	list;
+	wait_queue_head_t poll;
+	int event;
+};
 
 struct mnt_pcp {
 	int mnt_count;
@@ -49,3 +59,17 @@
 }
 
 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
+
+static inline void get_mnt_ns(struct mnt_namespace *ns)
+{
+	atomic_inc(&ns->count);
+}
+
+struct proc_mounts {
+	struct seq_file m; /* must be the first element */
+	struct mnt_namespace *ns;
+	struct path root;
+	int (*show)(struct seq_file *, struct vfsmount *);
+};
+
+extern const struct seq_operations mounts_op;