UBIFS: remount ro fixes

- preserve the idx_gc list - it will be needed in the same
state, should UBIFS be remounted rw again
- prevent remounting ro if we have switched to read only
mode (due to a fatal error)

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

fs/ubifs/gc.c

@@ -830,29 +830,21 @@ 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 @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.
+ * This function destroys the @c->idx_gc list. It is called when unmounting
+ * so locks are not needed. Returns zero in case of success and a negative
+ * error code in case of failure.
  */
-int ubifs_destroy_idx_gc(struct ubifs_info *c)
+void 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);
-		err = ubifs_change_one_lp(c, idx_gc->lnum, LPROPS_NC,
-					  LPROPS_NC, 0, LPROPS_TAKEN, -1);
-		if (err && !ret)
-			ret = err;
+		c->idx_gc_cnt -= 1;
 		list_del(&idx_gc->list);
 		kfree(idx_gc);
 	}
-
-	return ret;
 }
 
 /**

fs/ubifs/super.c

@@ -1687,10 +1687,6 @@ static void ubifs_remount_ro(struct ubifs_info *c)
 	if (err)
 		ubifs_ro_mode(c, err);
 
-	err = ubifs_destroy_idx_gc(c);
-	if (err)
-		ubifs_ro_mode(c, err);
-
 	free_wbufs(c);
 	vfree(c->orph_buf);
 	c->orph_buf = NULL;
@@ -1793,15 +1789,19 @@ 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");
+			ubifs_msg("cannot re-mount due to prior errors");
 			return -EINVAL;
 		}
 		err = ubifs_remount_rw(c);
 		if (err)
 			return err;
-	} else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY))
+	} else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY)) {
+		if (c->ro_media) {
+			ubifs_msg("cannot re-mount due to prior errors");
+			return -EINVAL;
+		}
 		ubifs_remount_ro(c);
+	}
 
 	if (c->bulk_read == 1)
 		bu_init(c);

fs/ubifs/ubifs.h

@@ -1594,7 +1594,7 @@ 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);
-int ubifs_destroy_idx_gc(struct ubifs_info *c);
+void 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);