JFS: Corrupted block map should not cause trap

Replace assert statements with better error handling.
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>

fs/jfs/jfs_dmap.c

@@ -74,7 +74,7 @@
 static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
 			int nblocks);
 static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval);
-static void dbBackSplit(dmtree_t * tp, int leafno);
+static int dbBackSplit(dmtree_t * tp, int leafno);
 static int dbJoin(dmtree_t * tp, int leafno, int newval);
 static void dbAdjTree(dmtree_t * tp, int leafno, int newval);
 static int dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc,
@@ -2466,7 +2466,9 @@ dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
 		 * that it is at the front of a binary buddy system.
 		 */
 		if (oldval == NOFREE) {
-			dbBackSplit((dmtree_t *) dcp, leafno);
+			rc = dbBackSplit((dmtree_t *) dcp, leafno);
+			if (rc)
+				return rc;
 			oldval = dcp->stree[ti];
 		}
 		dbSplit((dmtree_t *) dcp, leafno, dcp->budmin, newval);
@@ -2626,7 +2628,7 @@ static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
  *
  * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
  */
-static void dbBackSplit(dmtree_t * tp, int leafno)
+static int dbBackSplit(dmtree_t * tp, int leafno)
 {
 	int budsz, bud, w, bsz, size;
 	int cursz;
@@ -2661,7 +2663,10 @@ static void dbBackSplit(dmtree_t * tp, int leafno)
 		 */
 		for (w = leafno, bsz = budsz;; bsz <<= 1,
 		     w = (w < bud) ? w : bud) {
-			assert(bsz < le32_to_cpu(tp->dmt_nleafs));
+			if (bsz >= le32_to_cpu(tp->dmt_nleafs)) {
+				jfs_err("JFS: block map error in dbBackSplit");
+				return -EIO;
+			}
 
 			/* determine the buddy.
 			 */
@@ -2680,7 +2685,11 @@ static void dbBackSplit(dmtree_t * tp, int leafno)
 		}
 	}
 
-	assert(leaf[leafno] == size);
+	if (leaf[leafno] != size) {
+		jfs_err("JFS: wrong leaf value in dbBackSplit");
+		return -EIO;
+	}
+	return 0;
 }