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- /*
- * linux/fs/ext4/bitmap.c
- *
- * Copyright (C) 1992, 1993, 1994, 1995
- * Remy Card (card@masi.ibp.fr)
- * Laboratoire MASI - Institut Blaise Pascal
- * Universite Pierre et Marie Curie (Paris VI)
- */
- #include <linux/buffer_head.h>
- #include <linux/jbd2.h>
- #include "ext4.h"
- static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
- unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
- {
- unsigned int i, sum = 0;
- for (i = 0; i < numchars; i++)
- sum += nibblemap[bitmap[i] & 0xf] +
- nibblemap[(bitmap[i] >> 4) & 0xf];
- return sum;
- }
- int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
- struct ext4_group_desc *gdp,
- struct buffer_head *bh, int sz)
- {
- __u32 hi;
- __u32 provided, calculated;
- struct ext4_sb_info *sbi = EXT4_SB(sb);
- if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
- EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
- return 1;
- provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
- calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
- if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
- hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
- provided |= (hi << 16);
- } else
- calculated &= 0xFFFF;
- return provided == calculated;
- }
- void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
- struct ext4_group_desc *gdp,
- struct buffer_head *bh, int sz)
- {
- __u32 csum;
- struct ext4_sb_info *sbi = EXT4_SB(sb);
- if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
- EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
- return;
- csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
- gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
- if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
- gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
- }
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