ref: 9ae6dcb7e063d495267e7a53ddecb4d8356645ba
dir: /src/ext4_super.c/
/*
* Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
*
*
* HelenOS:
* Copyright (c) 2012 Martin Sucha
* Copyright (c) 2012 Frantisek Princ
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup lwext4
* @{
*/
/**
* @file ext4_super.h
* @brief Superblock operations.
*/
#include "ext4_config.h"
#include "ext4_types.h"
#include "ext4_misc.h"
#include "ext4_errno.h"
#include "ext4_debug.h"
#include "ext4_super.h"
#include "ext4_crc32.h"
uint32_t ext4_block_group_cnt(struct ext4_sblock *s)
{
uint64_t blocks_count = ext4_sb_get_blocks_cnt(s);
uint32_t blocks_per_group = ext4_get32(s, blocks_per_group);
uint32_t block_groups_count = (uint32_t)(blocks_count / blocks_per_group);
if (blocks_count % blocks_per_group)
block_groups_count++;
return block_groups_count;
}
uint32_t ext4_blocks_in_group_cnt(struct ext4_sblock *s, uint32_t bgid)
{
uint32_t block_group_count = ext4_block_group_cnt(s);
uint32_t blocks_per_group = ext4_get32(s, blocks_per_group);
uint64_t total_blocks = ext4_sb_get_blocks_cnt(s);
if (bgid < block_group_count - 1)
return blocks_per_group;
return (uint32_t)(total_blocks - ((block_group_count - 1) * blocks_per_group));
}
uint32_t ext4_inodes_in_group_cnt(struct ext4_sblock *s, uint32_t bgid)
{
uint32_t block_group_count = ext4_block_group_cnt(s);
uint32_t inodes_per_group = ext4_get32(s, inodes_per_group);
uint32_t total_inodes = ext4_get32(s, inodes_count);
if (bgid < block_group_count - 1)
return inodes_per_group;
return (total_inodes - ((block_group_count - 1) * inodes_per_group));
}
#if CONFIG_META_CSUM_ENABLE
static uint32_t ext4_sb_csum(struct ext4_sblock *s)
{
return ext4_crc32c(EXT4_CRC32_INIT, s,
offsetof(struct ext4_sblock, checksum));
}
#else
#define ext4_sb_csum(...) 0
#endif
static bool ext4_sb_verify_csum(struct ext4_sblock *s)
{
if (!ext4_sb_feature_ro_com(s, EXT4_FRO_COM_METADATA_CSUM))
return true;
if (s->checksum_type != to_le32(EXT4_CHECKSUM_CRC32C))
return false;
return s->checksum == to_le32(ext4_sb_csum(s));
}
static void ext4_sb_set_csum(struct ext4_sblock *s)
{
if (!ext4_sb_feature_ro_com(s, EXT4_FRO_COM_METADATA_CSUM))
return;
s->checksum = to_le32(ext4_sb_csum(s));
}
int ext4_sb_write(struct ext4_blockdev *bdev, struct ext4_sblock *s)
{
ext4_sb_set_csum(s);
return ext4_block_writebytes(bdev, EXT4_SUPERBLOCK_OFFSET, s,
EXT4_SUPERBLOCK_SIZE);
}
int ext4_sb_read(struct ext4_blockdev *bdev, struct ext4_sblock *s)
{
return ext4_block_readbytes(bdev, EXT4_SUPERBLOCK_OFFSET, s,
EXT4_SUPERBLOCK_SIZE);
}
bool ext4_sb_check(struct ext4_sblock *s)
{
if (ext4_get16(s, magic) != EXT4_SUPERBLOCK_MAGIC)
return false;
if (ext4_get32(s, inodes_count) == 0)
return false;
if (ext4_sb_get_blocks_cnt(s) == 0)
return false;
if (ext4_get32(s, blocks_per_group) == 0)
return false;
if (ext4_get32(s, inodes_per_group) == 0)
return false;
if (ext4_get16(s, inode_size) < 128)
return false;
if (ext4_get32(s, first_inode) < 11)
return false;
if (ext4_sb_get_desc_size(s) < EXT4_MIN_BLOCK_GROUP_DESCRIPTOR_SIZE)
return false;
if (ext4_sb_get_desc_size(s) > EXT4_MAX_BLOCK_GROUP_DESCRIPTOR_SIZE)
return false;
if (!ext4_sb_verify_csum(s))
return false;
return true;
}
static inline int is_power_of(uint32_t a, uint32_t b)
{
while (1) {
if (a < b)
return 0;
if (a == b)
return 1;
if ((a % b) != 0)
return 0;
a = a / b;
}
}
bool ext4_sb_sparse(uint32_t group)
{
if (group <= 1)
return 1;
if (!(group & 1))
return 0;
return (is_power_of(group, 7) || is_power_of(group, 5) ||
is_power_of(group, 3));
}
bool ext4_sb_is_super_in_bg(struct ext4_sblock *s, uint32_t group)
{
if (ext4_sb_feature_ro_com(s, EXT4_FRO_COM_SPARSE_SUPER) &&
!ext4_sb_sparse(group))
return false;
return true;
}
static uint32_t ext4_bg_num_gdb_meta(struct ext4_sblock *s, uint32_t group)
{
uint32_t dsc_per_block =
ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s);
uint32_t metagroup = group / dsc_per_block;
uint32_t first = metagroup * dsc_per_block;
uint32_t last = first + dsc_per_block - 1;
if (group == first || group == first + 1 || group == last)
return 1;
return 0;
}
static uint32_t ext4_bg_num_gdb_nometa(struct ext4_sblock *s, uint32_t group)
{
if (!ext4_sb_is_super_in_bg(s, group))
return 0;
uint32_t dsc_per_block =
ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s);
uint32_t db_count =
(ext4_block_group_cnt(s) + dsc_per_block - 1) / dsc_per_block;
if (ext4_sb_feature_incom(s, EXT4_FINCOM_META_BG))
return ext4_sb_first_meta_bg(s);
return db_count;
}
uint32_t ext4_bg_num_gdb(struct ext4_sblock *s, uint32_t group)
{
uint32_t dsc_per_block =
ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s);
uint32_t first_meta_bg = ext4_sb_first_meta_bg(s);
uint32_t metagroup = group / dsc_per_block;
if (!ext4_sb_feature_incom(s,EXT4_FINCOM_META_BG) ||
metagroup < first_meta_bg)
return ext4_bg_num_gdb_nometa(s, group);
return ext4_bg_num_gdb_meta(s, group);
}
uint32_t ext4_num_base_meta_clusters(struct ext4_sblock *s,
uint32_t block_group)
{
uint32_t num;
uint32_t dsc_per_block =
ext4_sb_get_block_size(s) / ext4_sb_get_desc_size(s);
num = ext4_sb_is_super_in_bg(s, block_group);
if (!ext4_sb_feature_incom(s, EXT4_FINCOM_META_BG) ||
block_group < ext4_sb_first_meta_bg(s) * dsc_per_block) {
if (num) {
num += ext4_bg_num_gdb(s, block_group);
num += ext4_get16(s, s_reserved_gdt_blocks);
}
} else {
num += ext4_bg_num_gdb(s, block_group);
}
uint32_t clustersize = 1024 << ext4_get32(s, log_cluster_size);
uint32_t cluster_ratio = clustersize / ext4_sb_get_block_size(s);
uint32_t v =
(num + cluster_ratio - 1) >> ext4_get32(s, log_cluster_size);
return v;
}
/**
* @}
*/