take check for new events in namespace (guts of mounts_poll()) to nam…

…espace.c

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namespace.c

@@ -737,6 +737,21 @@ static void m_stop(struct seq_file *m, void *v)
 	up_read(&namespace_sem);
 }
 
+int mnt_had_events(struct proc_mounts *p)
+{
+	struct mnt_namespace *ns = p->ns;
+	int res = 0;
+
+	spin_lock(&vfsmount_lock);
+	if (p->event != ns->event) {
+		p->event = ns->event;
+		res = 1;
+	}
+	spin_unlock(&vfsmount_lock);
+
+	return res;
+}
+
 struct proc_fs_info {
 	int flag;
 	const char *str;

fs/proc/base.c

@@ -647,17 +647,11 @@ static int mounts_release(struct inode *inode, struct file *file)
 static unsigned mounts_poll(struct file *file, poll_table *wait)
 {
 	struct proc_mounts *p = file->private_data;
-	struct mnt_namespace *ns = p->ns;
 	unsigned res = POLLIN | POLLRDNORM;
 
-	poll_wait(file, &ns->poll, wait);
-
-	spin_lock(&vfsmount_lock);
-	if (p->event != ns->event) {
-		p->event = ns->event;
+	poll_wait(file, &p->ns->poll, wait);
+	if (mnt_had_events(p))
 		res |= POLLERR | POLLPRI;
-	}
-	spin_unlock(&vfsmount_lock);
 
 	return res;
 }

include/linux/mnt_namespace.h

@@ -35,6 +35,7 @@ static inline void get_mnt_ns(struct mnt_namespace *ns)
 extern const struct seq_operations mounts_op;
 extern const struct seq_operations mountinfo_op;
 extern const struct seq_operations mountstats_op;
+extern int mnt_had_events(struct proc_mounts *);
 
 #endif
 #endif