UBIFS: fix LPT out-of-space bug (again)

The function to traverse and dirty the LPT was still not
dirtying all nodes, with the result that the LPT could
run out of space.
Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

fs/ubifs/lpt_commit.c

@@ -556,23 +556,23 @@ static int write_cnodes(struct ubifs_info *c)
 }
 
 /**
- * next_pnode - find next pnode.
+ * next_pnode_to_dirty - find next pnode to dirty.
  * @c: UBIFS file-system description object
  * @pnode: pnode
  *
- * This function returns the next pnode or %NULL if there are no more pnodes.
+ * This function returns the next pnode to dirty or %NULL if there are no more
+ * pnodes.  Note that pnodes that have never been written (lnum == 0) are
+ * skipped.
  */
-static struct ubifs_pnode *next_pnode(struct ubifs_info *c,
-				      struct ubifs_pnode *pnode)
+static struct ubifs_pnode *next_pnode_to_dirty(struct ubifs_info *c,
+					       struct ubifs_pnode *pnode)
 {
 	struct ubifs_nnode *nnode;
 	int iip;
 
 	/* Try to go right */
 	nnode = pnode->parent;
-	iip = pnode->iip + 1;
-	if (iip < UBIFS_LPT_FANOUT) {
-		/* We assume here that LEB zero is never an LPT LEB */
+	for (iip = pnode->iip + 1; iip < UBIFS_LPT_FANOUT; iip++) {
 		if (nnode->nbranch[iip].lnum)
 			return ubifs_get_pnode(c, nnode, iip);
 	}
@@ -583,8 +583,11 @@ static struct ubifs_pnode *next_pnode(struct ubifs_info *c,
 		nnode = nnode->parent;
 		if (!nnode)
 			return NULL;
-		/* We assume here that LEB zero is never an LPT LEB */
-	} while (iip >= UBIFS_LPT_FANOUT || !nnode->nbranch[iip].lnum);
+		for (; iip < UBIFS_LPT_FANOUT; iip++) {
+			if (nnode->nbranch[iip].lnum)
+				break;
+		}
+       } while (iip >= UBIFS_LPT_FANOUT);
 
 	/* Go right */
 	nnode = ubifs_get_nnode(c, nnode, iip);
@@ -593,12 +596,29 @@ static struct ubifs_pnode *next_pnode(struct ubifs_info *c,
 
 	/* Go down to level 1 */
 	while (nnode->level > 1) {
-		nnode = ubifs_get_nnode(c, nnode, 0);
+		for (iip = 0; iip < UBIFS_LPT_FANOUT; iip++) {
+			if (nnode->nbranch[iip].lnum)
+				break;
+		}
+		if (iip >= UBIFS_LPT_FANOUT) {
+			/*
+			 * Should not happen, but we need to keep going
+			 * if it does.
+			 */
+			iip = 0;
+		}
+		nnode = ubifs_get_nnode(c, nnode, iip);
 		if (IS_ERR(nnode))
 			return (void *)nnode;
 	}
 
-	return ubifs_get_pnode(c, nnode, 0);
+	for (iip = 0; iip < UBIFS_LPT_FANOUT; iip++)
+		if (nnode->nbranch[iip].lnum)
+			break;
+	if (iip >= UBIFS_LPT_FANOUT)
+		/* Should not happen, but we need to keep going if it does */
+		iip = 0;
+	return ubifs_get_pnode(c, nnode, iip);
 }
 
 /**
@@ -688,7 +708,7 @@ static int make_tree_dirty(struct ubifs_info *c)
 	pnode = pnode_lookup(c, 0);
 	while (pnode) {
 		do_make_pnode_dirty(c, pnode);
-		pnode = next_pnode(c, pnode);
+		pnode = next_pnode_to_dirty(c, pnode);
 		if (IS_ERR(pnode))
 			return PTR_ERR(pnode);
 	}