LXR linux/fs/ext4/bitmap.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/fs/ext4/bitmap.c
   4 *
   5 * Copyright (C) 1992, 1993, 1994, 1995
   6 * Remy Card (card@masi.ibp.fr)
   7 * Laboratoire MASI - Institut Blaise Pascal
   8 * Universite Pierre et Marie Curie (Paris VI)
   9 */
  10
  11#include <linux/buffer_head.h>
  12#include "ext4.h"
  13
  14unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
  15{
  16        return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
  17}
  18
  19int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  20                                  struct ext4_group_desc *gdp,
  21                                  struct buffer_head *bh, int sz)
  22{
  23        __u32 hi;
  24        __u32 provided, calculated;
  25        struct ext4_sb_info *sbi = EXT4_SB(sb);
  26
  27        if (!ext4_has_metadata_csum(sb))
  28                return 1;
  29
  30        provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
  31        calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  32        if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
  33                hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
  34                provided |= (hi << 16);
  35        } else
  36                calculated &= 0xFFFF;
  37
  38        return provided == calculated;
  39}
  40
  41void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  42                                struct ext4_group_desc *gdp,
  43                                struct buffer_head *bh, int sz)
  44{
  45        __u32 csum;
  46        struct ext4_sb_info *sbi = EXT4_SB(sb);
  47
  48        if (!ext4_has_metadata_csum(sb))
  49                return;
  50
  51        csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  52        gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  53        if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  54                gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  55}
  56
  57int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  58                                  struct ext4_group_desc *gdp,
  59                                  struct buffer_head *bh)
  60{
  61        __u32 hi;
  62        __u32 provided, calculated;
  63        struct ext4_sb_info *sbi = EXT4_SB(sb);
  64        int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  65
  66        if (!ext4_has_metadata_csum(sb))
  67                return 1;
  68
  69        provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
  70        calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  71        if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
  72                hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
  73                provided |= (hi << 16);
  74        } else
  75                calculated &= 0xFFFF;
  76
  77        if (provided == calculated)
  78                return 1;
  79
  80        return 0;
  81}
  82
  83void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  84                                struct ext4_group_desc *gdp,
  85                                struct buffer_head *bh)
  86{
  87        int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  88        __u32 csum;
  89        struct ext4_sb_info *sbi = EXT4_SB(sb);
  90
  91        if (!ext4_has_metadata_csum(sb))
  92                return;
  93
  94        csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  95        gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  96        if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
  97                gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  98}
  99