LXR linux/fs/ext4/bitmap.c

   1/*
   2 *  linux/fs/ext4/bitmap.c
   3 *
   4 * Copyright (C) 1992, 1993, 1994, 1995
   5 * Remy Card (card@masi.ibp.fr)
   6 * Laboratoire MASI - Institut Blaise Pascal
   7 * Universite Pierre et Marie Curie (Paris VI)
   8 */
   9
  10#include <linux/buffer_head.h>
  11#include "ext4.h"
  12
  13unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
  14{
  15        return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
  16}
  17
  18int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  19                                  struct ext4_group_desc *gdp,
  20                                  struct buffer_head *bh, int sz)
  21{
  22        __u32 hi;
  23        __u32 provided, calculated;
  24        struct ext4_sb_info *sbi = EXT4_SB(sb);
  25
  26        if (!ext4_has_metadata_csum(sb))
  27                return 1;
  28
  29        provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
  30        calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  31        if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
  32                hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
  33                provided |= (hi << 16);
  34        } else
  35                calculated &= 0xFFFF;
  36
  37        return provided == calculated;
  38}
  39
  40void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  41                                struct ext4_group_desc *gdp,
  42                                struct buffer_head *bh, int sz)
  43{
  44        __u32 csum;
  45        struct ext4_sb_info *sbi = EXT4_SB(sb);
  46
  47        if (!ext4_has_metadata_csum(sb))
  48                return;
  49
  50        csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  51        gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  52        if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  53                gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  54}
  55
  56int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  57                                  struct ext4_group_desc *gdp,
  58                                  struct buffer_head *bh)
  59{
  60        __u32 hi;
  61        __u32 provided, calculated;
  62        struct ext4_sb_info *sbi = EXT4_SB(sb);
  63        int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  64
  65        if (!ext4_has_metadata_csum(sb))
  66                return 1;
  67
  68        provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
  69        calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  70        if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
  71                hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
  72                provided |= (hi << 16);
  73        } else
  74                calculated &= 0xFFFF;
  75
  76        if (provided == calculated)
  77                return 1;
  78
  79        return 0;
  80}
  81
  82void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  83                                struct ext4_group_desc *gdp,
  84                                struct buffer_head *bh)
  85{
  86        int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  87        __u32 csum;
  88        struct ext4_sb_info *sbi = EXT4_SB(sb);
  89
  90        if (!ext4_has_metadata_csum(sb))
  91                return;
  92
  93        csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  94        gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  95        if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
  96                gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  97}
  98