UBIFS: fix LEB list freeing

When freeing the c->idx_lebs list, we have to release the LEBs as well,
because we might be called from mount to read-only mode code. Otherwise
the LEBs stay taken forever, which may cause problems when we re-mount
back ro RW mode.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

fs/ubifs/gc.c

@@ -830,21 +830,29 @@ int ubifs_gc_end_commit(struct ubifs_info *c)
  * ubifs_destroy_idx_gc - destroy idx_gc list.
  * @c: UBIFS file-system description object
  *
- * This function destroys the idx_gc list. It is called when unmounting or
- * remounting read-only so locks are not needed.
+ * This function destroys the @c->idx_gc list. It is called when unmounting or
+ * remounting read-only so locks are not needed. Returns zero in case of
+ * success and a negative error code in case of failure.
  */
-void ubifs_destroy_idx_gc(struct ubifs_info *c)
+int ubifs_destroy_idx_gc(struct ubifs_info *c)
 {
+	int ret = 0;
+
 	while (!list_empty(&c->idx_gc)) {
+		int err;
 		struct ubifs_gced_idx_leb *idx_gc;
 
 		idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb,
 				    list);
-		c->idx_gc_cnt -= 1;
+		err = ubifs_change_one_lp(c, idx_gc->lnum, LPROPS_NC,
+					  LPROPS_NC, 0, LPROPS_TAKEN, -1);
+		if (err && !ret)
+			ret = err;
 		list_del(&idx_gc->list);
 		kfree(idx_gc);
 	}
 
+	return ret;
 }
 
 /**

fs/ubifs/lprops.c

@@ -678,6 +678,9 @@ int ubifs_change_one_lp(struct ubifs_info *c, int lnum, int free, int dirty,
 
 out:
 	ubifs_release_lprops(c);
+	if (err)
+		ubifs_err("cannot change properties of LEB %d, error %d",
+			  lnum, err);
 	return err;
 }
 
@@ -714,6 +717,9 @@ int ubifs_update_one_lp(struct ubifs_info *c, int lnum, int free, int dirty,
 
 out:
 	ubifs_release_lprops(c);
+	if (err)
+		ubifs_err("cannot update properties of LEB %d, error %d",
+			  lnum, err);
 	return err;
 }
 
@@ -737,6 +743,8 @@ int ubifs_read_one_lp(struct ubifs_info *c, int lnum, struct ubifs_lprops *lp)
 	lpp = ubifs_lpt_lookup(c, lnum);
 	if (IS_ERR(lpp)) {
 		err = PTR_ERR(lpp);
+		ubifs_err("cannot read properties of LEB %d, error %d",
+			  lnum, err);
 		goto out;
 	}
 

fs/ubifs/super.c

@@ -1469,9 +1469,6 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 {
 	int err, lnum;
 
-	if (c->ro_media)
-		return -EINVAL;
-
 	mutex_lock(&c->umount_mutex);
 	c->remounting_rw = 1;
 	c->always_chk_crc = 1;
@@ -1605,9 +1602,13 @@ static int ubifs_remount_rw(struct ubifs_info *c)
  */
 static void commit_on_unmount(struct ubifs_info *c)
 {
-	struct super_block *sb = c->vfs_sb;
 	long long bud_bytes;
 
+	if (!c->fast_unmount) {
+		dbg_gen("skip committing - fast unmount enabled");
+		return;
+	}
+
 	/*
 	 * This function is called before the background thread is stopped, so
 	 * we may race with ongoing commit, which means we have to take
@@ -1617,8 +1618,11 @@ static void commit_on_unmount(struct ubifs_info *c)
 	bud_bytes = c->bud_bytes;
 	spin_unlock(&c->buds_lock);
 
-	if (!c->fast_unmount && !(sb->s_flags & MS_RDONLY) && bud_bytes)
+	if (bud_bytes) {
+		dbg_gen("run commit");
 		ubifs_run_commit(c);
+	} else
+		dbg_gen("journal is empty, do not run commit");
 }
 
 /**
@@ -1633,6 +1637,8 @@ static void ubifs_remount_ro(struct ubifs_info *c)
 	int i, err;
 
 	ubifs_assert(!c->need_recovery);
+	ubifs_assert(!c->ro_media);
+
 	commit_on_unmount(c);
 
 	mutex_lock(&c->umount_mutex);
@@ -1646,16 +1652,17 @@ static void ubifs_remount_ro(struct ubifs_info *c)
 		del_timer_sync(&c->jheads[i].wbuf.timer);
 	}
 
-	if (!c->ro_media) {
 	c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
 	c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
 	c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
 	err = ubifs_write_master(c);
 	if (err)
 		ubifs_ro_mode(c, err);
-	}
 
-	ubifs_destroy_idx_gc(c);
+	err = ubifs_destroy_idx_gc(c);
+	if (err)
+		ubifs_ro_mode(c, err);
+
 	free_wbufs(c);
 	vfree(c->orph_buf);
 	c->orph_buf = NULL;
@@ -1754,6 +1761,11 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
 	}
 
 	if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
+		if (c->ro_media) {
+			ubifs_msg("cannot re-mount R/W, UBIFS is working in "
+				  "R/O mode");
+			return -EINVAL;
+		}
 		err = ubifs_remount_rw(c);
 		if (err)
 			return err;
@@ -2044,7 +2056,7 @@ static void ubifs_kill_sb(struct super_block *sb)
 	 * We do 'commit_on_unmount()' here instead of 'ubifs_put_super()'
 	 * in order to be outside BKL.
 	 */
-	if (sb->s_root)
+	if (sb->s_root && !(sb->s_flags & MS_RDONLY))
 		commit_on_unmount(c);
 	/* The un-mount routine is actually done in put_super() */
 	generic_shutdown_super(sb);

fs/ubifs/ubifs.h

@@ -1593,7 +1593,7 @@ int ubifs_replay_journal(struct ubifs_info *c);
 int ubifs_garbage_collect(struct ubifs_info *c, int anyway);
 int ubifs_gc_start_commit(struct ubifs_info *c);
 int ubifs_gc_end_commit(struct ubifs_info *c);
-void ubifs_destroy_idx_gc(struct ubifs_info *c);
+int ubifs_destroy_idx_gc(struct ubifs_info *c);
 int ubifs_get_idx_gc_leb(struct ubifs_info *c);
 int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp);