/* *  linux/fs/ext4/bitmap.c * * Copyright (C) 1992, 1993, 1994, 1995 * Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) */ #include <linux/buffer_head.h>#include <linux/jbd2.h>#include "ext4.h" #ifdef EXT4FS_DEBUG static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars){	unsigned int i, sum = 0; 	if (!map)		return 0;	for (i = 0; i < numchars; i++)		sum += nibblemap[map->b_data[i] & 0xf] +			nibblemap[(map->b_data[i] >> 4) & 0xf];	return sum;} #endif  /*  EXT4FS_DEBUG  */ int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,				  struct ext4_group_desc *gdp,				  struct buffer_head *bh, int sz){	__u32 hi;	__u32 provided, calculated;	struct ext4_sb_info *sbi = EXT4_SB(sb); 	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))		return 1; 	provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);	calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);	if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {		hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);		provided |= (hi << 16);	} else		calculated &= 0xFFFF; 	return provided == calculated;} void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,				struct ext4_group_desc *gdp,				struct buffer_head *bh, int sz){	__u32 csum;	struct ext4_sb_info *sbi = EXT4_SB(sb); 	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))		return; 	csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);	gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);	if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)		gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);} int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,				  struct ext4_group_desc *gdp,				  struct buffer_head *bh, int sz){	__u32 hi;	__u32 provided, calculated;	struct ext4_sb_info *sbi = EXT4_SB(sb); 	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))		return 1; 	provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);	calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);	if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {		hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);		provided |= (hi << 16);	} else		calculated &= 0xFFFF; 	if (provided == calculated)		return 1; 	ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);	return 0;} void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,				struct ext4_group_desc *gdp,				struct buffer_head *bh, int sz){	__u32 csum;	struct ext4_sb_info *sbi = EXT4_SB(sb); 	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,			EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))		return; 	csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);	gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);	if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)		gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);}