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
  14 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
  15 {
  16         return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
  17 }
  18
  19 int 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
  41 void 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
  57 int 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
  83 void 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 }