bitmap.c

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/*
 *  linux/fs/ext4/bitmap.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card ([email protected])
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 */

#include <linux/buffer_head.h>
#include <linux/jbd2.h>
#include "ext4.h"

unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
{
    return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
}

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);
}

int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
                  struct ext4_group_desc *gdp,
                  struct buffer_head *bh)
{
    __u32 hi;
    __u32 provided, calculated;
    struct ext4_sb_info *sbi = EXT4_SB(sb);
    int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;

    if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
                    EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
        return 1;

    provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
    calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
    if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
        hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
        provided |= (hi << 16);
    } else
        calculated &= 0xFFFF;

    if (provided == calculated)
        return 1;

    return 0;
}

void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
                struct ext4_group_desc *gdp,
                struct buffer_head *bh)
{
    int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
    __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_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
    if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
        gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
}