fs/ext4/bitmap.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  linux/fs/ext4/bitmap.c
0004  *
0005  * Copyright (C) 1992, 1993, 1994, 1995
0006  * Remy Card (card@masi.ibp.fr)
0007  * Laboratoire MASI - Institut Blaise Pascal
0008  * Universite Pierre et Marie Curie (Paris VI)
0009  */
0010
0011 #include <linux/buffer_head.h>
0012 #include "ext4.h"
0013
0014 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
0015 {
0016     return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
0017 }
0018
0019 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
0020                   struct ext4_group_desc *gdp,
0021                   struct buffer_head *bh, int sz)
0022 {
0023     __u32 hi;
0024     __u32 provided, calculated;
0025     struct ext4_sb_info *sbi = EXT4_SB(sb);
0026
0027     if (!ext4_has_metadata_csum(sb))
0028         return 1;
0029
0030     provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
0031     calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
0032     if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
0033         hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
0034         provided |= (hi << 16);
0035     } else
0036         calculated &= 0xFFFF;
0037
0038     return provided == calculated;
0039 }
0040
0041 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
0042                 struct ext4_group_desc *gdp,
0043                 struct buffer_head *bh, int sz)
0044 {
0045     __u32 csum;
0046     struct ext4_sb_info *sbi = EXT4_SB(sb);
0047
0048     if (!ext4_has_metadata_csum(sb))
0049         return;
0050
0051     csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
0052     gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
0053     if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
0054         gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
0055 }
0056
0057 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
0058                   struct ext4_group_desc *gdp,
0059                   struct buffer_head *bh)
0060 {
0061     __u32 hi;
0062     __u32 provided, calculated;
0063     struct ext4_sb_info *sbi = EXT4_SB(sb);
0064     int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
0065
0066     if (!ext4_has_metadata_csum(sb))
0067         return 1;
0068
0069     provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
0070     calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
0071     if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
0072         hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
0073         provided |= (hi << 16);
0074     } else
0075         calculated &= 0xFFFF;
0076
0077     if (provided == calculated)
0078         return 1;
0079
0080     return 0;
0081 }
0082
0083 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
0084                 struct ext4_group_desc *gdp,
0085                 struct buffer_head *bh)
0086 {
0087     int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
0088     __u32 csum;
0089     struct ext4_sb_info *sbi = EXT4_SB(sb);
0090
0091     if (!ext4_has_metadata_csum(sb))
0092         return;
0093
0094     csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
0095     gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
0096     if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
0097         gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
0098 }