Quelle  bitmap.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 *  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 "ext4.h"

unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
{
 return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
}

int ext4_inode_bitmap_csum_verify(struct super_block *sb,
      struct ext4_group_desc *gdp,
      struct buffer_head *bh)
{
 __u32 hi;
 __u32 provided, calculated;
 struct ext4_sb_info *sbi = EXT4_SB(sb);
 int sz;

 if (!ext4_has_feature_metadata_csum(sb))
  return 1;

 sz = EXT4_INODES_PER_GROUP(sb) >> 3;
 provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
 calculated = ext4_chksum(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,
    struct ext4_group_desc *gdp,
    struct buffer_head *bh)
{
 __u32 csum;
 struct ext4_sb_info *sbi = EXT4_SB(sb);
 int sz;

 if (!ext4_has_feature_metadata_csum(sb))
  return;

 sz = EXT4_INODES_PER_GROUP(sb) >> 3;
 csum = ext4_chksum(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,
      struct ext4_group_desc *gdp,
      struct buffer_head *bh)
{
 __u32 hi;
 __u32 provided, calculated;
 struct ext4_sb_info *sbi = EXT4_SB(sb);
 int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;

 if (!ext4_has_feature_metadata_csum(sb))
  return 1;

 provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
 calculated = ext4_chksum(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;

 return provided == calculated;
}

void ext4_block_bitmap_csum_set(struct super_block *sb,
    struct ext4_group_desc *gdp,
    struct buffer_head *bh)
{
 int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
 __u32 csum;
 struct ext4_sb_info *sbi = EXT4_SB(sb);

 if (!ext4_has_feature_metadata_csum(sb))
  return;

 csum = ext4_chksum(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);
}