[PATCH] teach seq_file to discard entries

Allow ->show() return SEQ_SKIP; that will discard all
output from that element and move on.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/pnode.h b/fs/pnode.h
index f249be2..973c3f8 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -35,4 +35,5 @@
 		struct list_head *);
 int propagate_umount(struct list_head *);
 int propagate_mount_busy(struct vfsmount *, int);
+void mnt_release_group_id(struct vfsmount *);
 #endif /* _LINUX_PNODE_H */