+/*
+ * add_new_gdb_meta_bg is the sister of add_new_gdb.
+ */
+static int add_new_gdb_meta_bg(struct super_block *sb,
+ handle_t *handle, ext4_group_t group) {
+ ext4_fsblk_t gdblock;
+ struct buffer_head *gdb_bh;
+ struct buffer_head **o_group_desc, **n_group_desc;
+ unsigned long gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
+ int err;
+
+ gdblock = ext4_meta_bg_first_block_no(sb, group) +
+ ext4_bg_has_super(sb, group);
+ gdb_bh = sb_bread(sb, gdblock);
+ if (!gdb_bh)
+ return -EIO;
+ n_group_desc = ext4_kvmalloc((gdb_num + 1) *
+ sizeof(struct buffer_head *),
+ GFP_NOFS);
+ if (!n_group_desc) {
+ err = -ENOMEM;
+ ext4_warning(sb, "not enough memory for %lu groups",
+ gdb_num + 1);
+ return err;
+ }
+
+ o_group_desc = EXT4_SB(sb)->s_group_desc;
+ memcpy(n_group_desc, o_group_desc,
+ EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
+ n_group_desc[gdb_num] = gdb_bh;
+ EXT4_SB(sb)->s_group_desc = n_group_desc;
+ EXT4_SB(sb)->s_gdb_count++;
+ ext4_kvfree(o_group_desc);
+ err = ext4_journal_get_write_access(handle, gdb_bh);
+ if (unlikely(err))
+ brelse(gdb_bh);
+ return err;
+}
+