proc/maps: replace proc_maps_private->pid with "struct inode *inode"

m_start() can use get_proc_task() instead, and "struct inode *"
provides more potentially useful info, see the next changes.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_nommu.c

@@ -212,7 +212,7 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 	loff_t n = *pos;
 
 	/* pin the task and mm whilst we play with them */
-	priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
+	priv->task = get_proc_task(priv->inode);
 	if (!priv->task)
 		return ERR_PTR(-ESRCH);
 
@@ -276,7 +276,7 @@ static int maps_open(struct inode *inode, struct file *file,
 	if (!priv)
 		return -ENOMEM;
 
-	priv->pid = proc_pid(inode);
+	priv->inode = inode;
 	priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
 	if (IS_ERR(priv->mm)) {
 		int err = PTR_ERR(priv->mm);