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
  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,
  20                                   struct ext4_group_desc *gdp,
  21                                   struct buffer_head *bh)
  22 {
  23         __u32 hi;
  24         __u32 provided, calculated;
  25         struct ext4_sb_info *sbi = EXT4_SB(sb);
  26         int sz;
  27
  28         if (!ext4_has_metadata_csum(sb))
  29                 return 1;
  30
  31         sz = EXT4_INODES_PER_GROUP(sb) >> 3;
  32         provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
  33         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  34         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
  35                 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
  36                 provided |= (hi << 16);
  37         } else
  38                 calculated &= 0xFFFF;
  39
  40         return provided == calculated;
  41 }
  42
  43 void ext4_inode_bitmap_csum_set(struct super_block *sb,
  44                                 struct ext4_group_desc *gdp,
  45                                 struct buffer_head *bh)
  46 {
  47         __u32 csum;
  48         struct ext4_sb_info *sbi = EXT4_SB(sb);
  49         int sz;
  50
  51         if (!ext4_has_metadata_csum(sb))
  52                 return;
  53
  54         sz = EXT4_INODES_PER_GROUP(sb) >> 3;
  55         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  56         gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  57         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  58                 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  59 }
  60
  61 int ext4_block_bitmap_csum_verify(struct super_block *sb,
  62                                   struct ext4_group_desc *gdp,
  63                                   struct buffer_head *bh)
  64 {
  65         __u32 hi;
  66         __u32 provided, calculated;
  67         struct ext4_sb_info *sbi = EXT4_SB(sb);
  68         int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  69
  70         if (!ext4_has_metadata_csum(sb))
  71                 return 1;
  72
  73         provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
  74         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  75         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
  76                 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
  77                 provided |= (hi << 16);
  78         } else
  79                 calculated &= 0xFFFF;
  80
  81         return provided == calculated;
  82 }
  83
  84 void ext4_block_bitmap_csum_set(struct super_block *sb,
  85                                 struct ext4_group_desc *gdp,
  86                                 struct buffer_head *bh)
  87 {
  88         int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  89         __u32 csum;
  90         struct ext4_sb_info *sbi = EXT4_SB(sb);
  91
  92         if (!ext4_has_metadata_csum(sb))
  93                 return;
  94
  95         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  96         gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  97         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
  98                 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  99 }