UBIFS: check ubifs_scan error codes better

The 'ubifs_scan()' function returns -EUCLEAN if something is corrupted
and recovery is needed, otherwise it returns other error codes. However,
in few places UBIFS does not check the error codes and runs recovery.
This patch changes this behavior and makes UBIFS start recovery only
on -EUCLEAN errors.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: NAdrian Hunter <Adrian.Hunter@nokia.com>

fs/ubifs/master.c

@@ -29,7 +29,8 @@
  * @c: UBIFS file-system description object
  *
  * This function scans the master node LEBs and search for the latest master
- * node. Returns zero in case of success and a negative error code in case of
+ * node. Returns zero in case of success, %-EUCLEAN if there master area is
+ * corrupted and requires recovery, and a negative error code in case of
  * failure.
  */
 static int scan_for_master(struct ubifs_info *c)
@@ -48,7 +49,7 @@ static int scan_for_master(struct ubifs_info *c)
 		snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
 				  list);
 		if (snod->type != UBIFS_MST_NODE)
-			goto out;
+			goto out_dump;
 		memcpy(c->mst_node, snod->node, snod->len);
 		offs = snod->offs;
 	}
@@ -65,7 +66,7 @@ static int scan_for_master(struct ubifs_info *c)
 		goto out;
 	snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node, list);
 	if (snod->type != UBIFS_MST_NODE)
-		goto out;
+		goto out_dump;
 	if (snod->offs != offs)
 		goto out;
 	if (memcmp((void *)c->mst_node + UBIFS_CH_SZ,
@@ -78,6 +79,12 @@ static int scan_for_master(struct ubifs_info *c)
 
 out:
 	ubifs_scan_destroy(sleb);
+	return -EUCLEAN;
+
+out_dump:
+	ubifs_err("unexpected node type %d master LEB %d:%d",
+		  snod->type, lnum, snod->offs);
+	ubifs_scan_destroy(sleb);
 	return -EINVAL;
 }
 
@@ -256,6 +263,7 @@ int ubifs_read_master(struct ubifs_info *c)
 
 	err = scan_for_master(c);
 	if (err) {
+		if (err == -EUCLEAN)
 			err = ubifs_recover_master_node(c);
 		if (err)
 			/*

fs/ubifs/orphan.c

@@ -672,6 +672,7 @@ static int kill_orphans(struct ubifs_info *c)
 		dbg_rcvry("LEB %d", lnum);
 		sleb = ubifs_scan(c, lnum, 0, c->sbuf, 1);
 		if (IS_ERR(sleb)) {
+			if (PTR_ERR(sleb) == -EUCLEAN)
 				sleb = ubifs_recover_leb(c, lnum, 0, c->sbuf, 0);
 			if (IS_ERR(sleb)) {
 				err = PTR_ERR(sleb);