fa77dcfafe
Compute and verify the checksum of the block bitmap; this checksum is stored in the block group descriptor. Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
114 lines
3.1 KiB
C
114 lines
3.1 KiB
C
/*
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* linux/fs/ext4/bitmap.c
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*
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* Copyright (C) 1992, 1993, 1994, 1995
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* Remy Card (card@masi.ibp.fr)
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* Laboratoire MASI - Institut Blaise Pascal
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* Universite Pierre et Marie Curie (Paris VI)
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*/
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#include <linux/buffer_head.h>
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#include <linux/jbd2.h>
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#include "ext4.h"
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#ifdef EXT4FS_DEBUG
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static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
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unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
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{
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unsigned int i, sum = 0;
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if (!map)
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return 0;
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for (i = 0; i < numchars; i++)
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sum += nibblemap[map->b_data[i] & 0xf] +
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nibblemap[(map->b_data[i] >> 4) & 0xf];
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return sum;
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}
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#endif /* EXT4FS_DEBUG */
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int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
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struct ext4_group_desc *gdp,
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struct buffer_head *bh, int sz)
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{
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__u32 hi;
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__u32 provided, calculated;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
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EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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return 1;
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provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
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calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
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if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
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hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
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provided |= (hi << 16);
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} else
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calculated &= 0xFFFF;
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return provided == calculated;
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}
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void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
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struct ext4_group_desc *gdp,
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struct buffer_head *bh, int sz)
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{
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__u32 csum;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
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EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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return;
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csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
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gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
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if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
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gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
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}
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int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
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struct ext4_group_desc *gdp,
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struct buffer_head *bh, int sz)
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{
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__u32 hi;
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__u32 provided, calculated;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
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EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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return 1;
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provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
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calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
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if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
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hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
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provided |= (hi << 16);
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} else
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calculated &= 0xFFFF;
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if (provided == calculated)
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return 1;
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ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);
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return 0;
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}
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void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
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struct ext4_group_desc *gdp,
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struct buffer_head *bh, int sz)
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{
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__u32 csum;
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struct ext4_sb_info *sbi = EXT4_SB(sb);
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if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
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EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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return;
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csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
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gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
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if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
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gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
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}
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