Merge branch 'for-linus' of git://git.infradead.org/ubifs-2.6

* 'for-linus' of git://git.infradead.org/ubifs-2.6:
  UBIFS: fix master node recovery
  UBIFS: fix false assertion warning in case of I/O failures
  UBIFS: fix false space checking failure

fs/ubifs/recovery.c

@@ -317,6 +317,32 @@ int ubifs_recover_master_node(struct ubifs_info *c)
 			goto out_free;
 		}
 		memcpy(c->rcvrd_mst_node, c->mst_node, UBIFS_MST_NODE_SZ);
+
+		/*
+		 * We had to recover the master node, which means there was an
+		 * unclean reboot. However, it is possible that the master node
+		 * is clean at this point, i.e., %UBIFS_MST_DIRTY is not set.
+		 * E.g., consider the following chain of events:
+		 *
+		 * 1. UBIFS was cleanly unmounted, so the master node is clean
+		 * 2. UBIFS is being mounted R/W and starts changing the master
+		 *    node in the first (%UBIFS_MST_LNUM). A power cut happens,
+		 *    so this LEB ends up with some amount of garbage at the
+		 *    end.
+		 * 3. UBIFS is being mounted R/O. We reach this place and
+		 *    recover the master node from the second LEB
+		 *    (%UBIFS_MST_LNUM + 1). But we cannot update the media
+		 *    because we are being mounted R/O. We have to defer the
+		 *    operation.
+		 * 4. However, this master node (@c->mst_node) is marked as
+		 *    clean (since the step 1). And if we just return, the
+		 *    mount code will be confused and won't recover the master
+		 *    node when it is re-mounter R/W later.
+		 *
+		 *    Thus, to force the recovery by marking the master node as
+		 *    dirty.
+		 */
+		c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
 	} else {
 		/* Write the recovered master node */
 		c->max_sqnum = le64_to_cpu(mst->ch.sqnum) - 1;

fs/ubifs/super.c

@@ -1671,14 +1671,25 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 	if (err)
 		goto out;
 
+	dbg_gen("re-mounted read-write");
+	c->remounting_rw = 0;
+
 	if (c->need_recovery) {
 		c->need_recovery = 0;
 		ubifs_msg("deferred recovery completed");
-	}
-
-	dbg_gen("re-mounted read-write");
-	c->remounting_rw = 0;
+	} else {
+		/*
+		 * Do not run the debugging space check if the were doing
+		 * recovery, because when we saved the information we had the
+		 * file-system in a state where the TNC and lprops has been
+		 * modified in memory, but all the I/O operations (including a
+		 * commit) were deferred. So the file-system was in
+		 * "non-committed" state. Now the file-system is in committed
+		 * state, and of course the amount of free space will change
+		 * because, for example, the old index size was imprecise.
+		 */
 		err = dbg_check_space_info(c);
+	}
 	mutex_unlock(&c->umount_mutex);
 	return err;
 
@@ -1761,10 +1772,12 @@ static void ubifs_put_super(struct super_block *sb)
 	 * of the media. For example, there will be dirty inodes if we failed
 	 * to write them back because of I/O errors.
 	 */
+	if (!c->ro_error) {
 		ubifs_assert(atomic_long_read(&c->dirty_pg_cnt) == 0);
 		ubifs_assert(c->budg_idx_growth == 0);
 		ubifs_assert(c->budg_dd_growth == 0);
 		ubifs_assert(c->budg_data_growth == 0);
+	}
 
 	/*
 	 * The 'c->umount_lock' prevents races between UBIFS memory shrinker