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 <linux/jbd2.h> 12 #include "ext4.h" 13 14 #ifdef EXT4FS_DEBUG 15 16 static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; 17 18 unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars) 19 { 20 unsigned int i, sum = 0; 21 22 if (!map) 23 return 0; 24 for (i = 0; i < numchars; i++) 25 sum += nibblemap[map->b_data[i] & 0xf] + 26 nibblemap[(map->b_data[i] >> 4) & 0xf]; 27 return sum; 28 } 29 30 #endif /* EXT4FS_DEBUG */ 31 32 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group, 33 struct ext4_group_desc *gdp, 34 struct buffer_head *bh, int sz) 35 { 36 __u32 hi; 37 __u32 provided, calculated; 38 struct ext4_sb_info *sbi = EXT4_SB(sb); 39 40 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 41 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 42 return 1; 43 44 provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo); 45 calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 46 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) { 47 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi); 48 provided |= (hi << 16); 49 } else 50 calculated &= 0xFFFF; 51 52 return provided == calculated; 53 } 54 55 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group, 56 struct ext4_group_desc *gdp, 57 struct buffer_head *bh, int sz) 58 { 59 __u32 csum; 60 struct ext4_sb_info *sbi = EXT4_SB(sb); 61 62 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 63 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 64 return; 65 66 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 67 gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF); 68 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) 69 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16); 70 } 71 72 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group, 73 struct ext4_group_desc *gdp, 74 struct buffer_head *bh, int sz) 75 { 76 __u32 hi; 77 __u32 provided, calculated; 78 struct ext4_sb_info *sbi = EXT4_SB(sb); 79 80 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 81 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 82 return 1; 83 84 provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo); 85 calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 86 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) { 87 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi); 88 provided |= (hi << 16); 89 } else 90 calculated &= 0xFFFF; 91 92 if (provided == calculated) 93 return 1; 94 95 ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group); 96 return 0; 97 } 98 99 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group, 100 struct ext4_group_desc *gdp, 101 struct buffer_head *bh, int sz) 102 { 103 __u32 csum; 104 struct ext4_sb_info *sbi = EXT4_SB(sb); 105 106 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 107 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 108 return; 109 110 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 111 gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF); 112 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) 113 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16); 114 } 115