+/* Initializes an uninitialized block bitmap */
+void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
+ ext4_group_t block_group,
+ struct ext4_group_desc *gdp)
+{
+ unsigned int bit, bit_max;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ ext4_fsblk_t start, tmp;
+ int flex_bg = 0;
+
+ J_ASSERT_BH(bh, buffer_locked(bh));
+
+ /* If checksum is bad mark all blocks used to prevent allocation
+ * essentially implementing a per-group read-only flag. */
+ if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
+ ext4_error(sb, "Checksum bad for group %u", block_group);
+ ext4_free_group_clusters_set(sb, gdp, 0);
+ ext4_free_inodes_set(sb, gdp, 0);
+ ext4_itable_unused_set(sb, gdp, 0);
+ memset(bh->b_data, 0xff, sb->s_blocksize);
+ return;
+ }
+ memset(bh->b_data, 0, sb->s_blocksize);