[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>
diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index 4cb4d76..9fc4833c 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c
@@ -1123,7 +1123,8 @@
 	size_t retlen;
 	int ret;
 
-	dbg_readinode("ino #%u nlink is %d\n", f->inocache->ino, f->inocache->nlink);
+	dbg_readinode("ino #%u pino/nlink is %d\n", f->inocache->ino,
+		      f->inocache->pino_nlink);
 
 	memset(&rii, 0, sizeof(rii));
 
@@ -1358,7 +1359,7 @@
 		}
 		dbg_readinode("creating inocache for root inode\n");
 		memset(f->inocache, 0, sizeof(struct jffs2_inode_cache));
-		f->inocache->ino = f->inocache->nlink = 1;
+		f->inocache->ino = f->inocache->pino_nlink = 1;
 		f->inocache->nodes = (struct jffs2_raw_node_ref *)f->inocache;
 		f->inocache->state = INO_STATE_READING;
 		jffs2_add_ino_cache(c, f->inocache);
@@ -1401,7 +1402,7 @@
 	jffs2_clear_acl(f);
 	jffs2_xattr_delete_inode(c, f->inocache);
 	mutex_lock(&f->sem);
-	deleted = f->inocache && !f->inocache->nlink;
+	deleted = f->inocache && !f->inocache->pino_nlink;
 
 	if (f->inocache && f->inocache->state != INO_STATE_CHECKING)
 		jffs2_set_inocache_state(c, f->inocache, INO_STATE_CLEARING);