[JFFS2] Track parent inode for directories (for NFS export)

To support NFS export, we need to know the parent inode of directories.
Rather than growing the jffs2_inode_cache structure, share space with
the nlink field -- which was always set to 1 for directories anyway.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

fs/jffs2/nodemgmt.c

diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
index 9df8f3e..a9bf9603 100644
--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -709,7 +709,7 @@
 				break;
 #endif
 			default:
-				if (ic->nodes == (void *)ic && ic->nlink == 0)
+				if (ic->nodes == (void *)ic && ic->pino_nlink == 0)
 					jffs2_del_ino_cache(c, ic);
 				break;
 		}