static int ext4_check_descriptors(struct super_block *sb,
				  ext4_fsblk_t sb_block,
				  ext4_group_t *first_not_zeroed)
{
	struct ext4_sb_info *sbi = EXT4_SB(sb);
	ext4_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
	ext4_fsblk_t last_block;
	ext4_fsblk_t last_bg_block = sb_block + ext4_bg_num_gdb(sb, 0) + 1;
	ext4_fsblk_t block_bitmap;
	ext4_fsblk_t inode_bitmap;
	ext4_fsblk_t inode_table;
	int flexbg_flag = 0;
	ext4_group_t i, grp = sbi->s_groups_count;

	if (ext4_has_feature_flex_bg(sb))
		flexbg_flag = 1;

	ext4_debug("Checking group descriptors");

	for (i = 0; i < sbi->s_groups_count; i++) {
		struct ext4_group_desc *gdp = ext4_get_group_desc(sb, i, NULL);

		if (i == sbi->s_groups_count - 1 || flexbg_flag)
			last_block = ext4_blocks_count(sbi->s_es) - 1;
		else
			last_block = first_block +
				(EXT4_BLOCKS_PER_GROUP(sb) - 1);

		if ((grp == sbi->s_groups_count) &&
		   !(gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED)))
			grp = i;

		block_bitmap = ext4_block_bitmap(sb, gdp);
		if (block_bitmap == sb_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
				 "Block bitmap for group %u overlaps "
				 "superblock", i);
			if (!sb_rdonly(sb))
				return 0;
		}
		if (block_bitmap >= sb_block + 1 &&
		    block_bitmap <= last_bg_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
				 "Block bitmap for group %u overlaps "
				 "block group descriptors", i);
			if (!sb_rdonly(sb))
				return 0;
		}
		if (block_bitmap < first_block || block_bitmap > last_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
			       "Block bitmap for group %u not in group "
			       "(block %llu)!", i, block_bitmap);
			return 0;
		}
		inode_bitmap = ext4_inode_bitmap(sb, gdp);
		if (inode_bitmap == sb_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
				 "Inode bitmap for group %u overlaps "
				 "superblock", i);
			if (!sb_rdonly(sb))
				return 0;
		}
		if (inode_bitmap >= sb_block + 1 &&
		    inode_bitmap <= last_bg_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
				 "Inode bitmap for group %u overlaps "
				 "block group descriptors", i);
			if (!sb_rdonly(sb))
				return 0;
		}
		if (inode_bitmap < first_block || inode_bitmap > last_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
			       "Inode bitmap for group %u not in group "
			       "(block %llu)!", i, inode_bitmap);
			return 0;
		}
		inode_table = ext4_inode_table(sb, gdp);
		if (inode_table == sb_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
				 "Inode table for group %u overlaps "
				 "superblock", i);
			if (!sb_rdonly(sb))
				return 0;
		}
		if (inode_table >= sb_block + 1 &&
		    inode_table <= last_bg_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
				 "Inode table for group %u overlaps "
				 "block group descriptors", i);
			if (!sb_rdonly(sb))
				return 0;
		}
		if (inode_table < first_block ||
		    inode_table + sbi->s_itb_per_group - 1 > last_block) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
			       "Inode table for group %u not in group "
			       "(block %llu)!", i, inode_table);
			return 0;
		}
		ext4_lock_group(sb, i);
		if (!ext4_group_desc_csum_verify(sb, i, gdp)) {
			ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
				 "Checksum for group %u failed (%u!=%u)",
				 i, le16_to_cpu(ext4_group_desc_csum(sb, i,
				     gdp)), le16_to_cpu(gdp->bg_checksum));
			if (!sb_rdonly(sb)) {
				ext4_unlock_group(sb, i);
				return 0;
			}
		}
		ext4_unlock_group(sb, i);
		if (!flexbg_flag)
			first_block += EXT4_BLOCKS_PER_GROUP(sb);
	}
	if (NULL != first_not_zeroed)
		*first_not_zeroed = grp;
	return 1;
}