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exfat: add bitmap operations
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This adds the implementation of bitmap operations for exfat.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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namjaejeon authored and Al Viro committed Mar 6, 2020
1 parent 3102386 commit 1e49a94
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280 changes: 280 additions & 0 deletions fs/exfat/balloc.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
*/

#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/buffer_head.h>

#include "exfat_raw.h"
#include "exfat_fs.h"

static const unsigned char free_bit[] = {
0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/* 0 ~ 19*/
0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3,/* 20 ~ 39*/
0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/* 40 ~ 59*/
0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/* 60 ~ 79*/
0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2,/* 80 ~ 99*/
0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3,/*100 ~ 119*/
0, 1, 0, 2, 0, 1, 0, 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*120 ~ 139*/
0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5,/*140 ~ 159*/
0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*160 ~ 179*/
0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3,/*180 ~ 199*/
0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*200 ~ 219*/
0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/*220 ~ 239*/
0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0 /*240 ~ 254*/
};

static const unsigned char used_bit[] = {
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3,/* 0 ~ 19*/
2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4,/* 20 ~ 39*/
2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,/* 40 ~ 59*/
4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,/* 60 ~ 79*/
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,/* 80 ~ 99*/
3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,/*100 ~ 119*/
4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4,/*120 ~ 139*/
3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,/*140 ~ 159*/
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5,/*160 ~ 179*/
4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5,/*180 ~ 199*/
3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6,/*200 ~ 219*/
5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,/*220 ~ 239*/
4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8 /*240 ~ 255*/
};

/*
* Allocation Bitmap Management Functions
*/
static int exfat_allocate_bitmap(struct super_block *sb,
struct exfat_dentry *ep)
{
struct exfat_sb_info *sbi = EXFAT_SB(sb);
long long map_size;
unsigned int i, need_map_size;
sector_t sector;

sbi->map_clu = le32_to_cpu(ep->dentry.bitmap.start_clu);
map_size = le64_to_cpu(ep->dentry.bitmap.size);
need_map_size = ((EXFAT_DATA_CLUSTER_COUNT(sbi) - 1) / BITS_PER_BYTE)
+ 1;
if (need_map_size != map_size) {
exfat_msg(sb, KERN_ERR,
"bogus allocation bitmap size(need : %u, cur : %lld)",
need_map_size, map_size);
/*
* Only allowed when bogus allocation
* bitmap size is large
*/
if (need_map_size > map_size)
return -EIO;
}
sbi->map_sectors = ((need_map_size - 1) >>
(sb->s_blocksize_bits)) + 1;
sbi->vol_amap = kmalloc_array(sbi->map_sectors,
sizeof(struct buffer_head *), GFP_KERNEL);
if (!sbi->vol_amap)
return -ENOMEM;

sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
for (i = 0; i < sbi->map_sectors; i++) {
sbi->vol_amap[i] = sb_bread(sb, sector + i);
if (!sbi->vol_amap[i]) {
/* release all buffers and free vol_amap */
int j = 0;

while (j < i)
brelse(sbi->vol_amap[j++]);

kfree(sbi->vol_amap);
sbi->vol_amap = NULL;
return -EIO;
}
}

sbi->pbr_bh = NULL;
return 0;
}

int exfat_load_bitmap(struct super_block *sb)
{
unsigned int i, type;
struct exfat_chain clu;
struct exfat_sb_info *sbi = EXFAT_SB(sb);

exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
while (clu.dir != EXFAT_EOF_CLUSTER) {
for (i = 0; i < sbi->dentries_per_clu; i++) {
struct exfat_dentry *ep;
struct buffer_head *bh;

ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
if (!ep)
return -EIO;

type = exfat_get_entry_type(ep);
if (type == TYPE_UNUSED)
break;
if (type != TYPE_BITMAP)
continue;
if (ep->dentry.bitmap.flags == 0x0) {
int err;

err = exfat_allocate_bitmap(sb, ep);
brelse(bh);
return err;
}
brelse(bh);
}

if (exfat_get_next_cluster(sb, &clu.dir))
return -EIO;
}

return -EINVAL;
}

void exfat_free_bitmap(struct exfat_sb_info *sbi)
{
int i;

brelse(sbi->pbr_bh);

for (i = 0; i < sbi->map_sectors; i++)
__brelse(sbi->vol_amap[i]);

kfree(sbi->vol_amap);
}

/*
* If the value of "clu" is 0, it means cluster 2 which is the first cluster of
* the cluster heap.
*/
int exfat_set_bitmap(struct inode *inode, unsigned int clu)
{
int i, b;
unsigned int ent_idx;
struct super_block *sb = inode->i_sb;
struct exfat_sb_info *sbi = EXFAT_SB(sb);

WARN_ON(clu < EXFAT_FIRST_CLUSTER);
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);

set_bit_le(b, sbi->vol_amap[i]->b_data);
exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));
return 0;
}

/*
* If the value of "clu" is 0, it means cluster 2 which is the first cluster of
* the cluster heap.
*/
void exfat_clear_bitmap(struct inode *inode, unsigned int clu)
{
int i, b;
unsigned int ent_idx;
struct super_block *sb = inode->i_sb;
struct exfat_sb_info *sbi = EXFAT_SB(sb);
struct exfat_mount_options *opts = &sbi->options;

WARN_ON(clu < EXFAT_FIRST_CLUSTER);
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);

clear_bit_le(b, sbi->vol_amap[i]->b_data);
exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));

if (opts->discard) {
int ret_discard;

ret_discard = sb_issue_discard(sb,
exfat_cluster_to_sector(sbi, clu +
EXFAT_RESERVED_CLUSTERS),
(1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);

if (ret_discard == -EOPNOTSUPP) {
exfat_msg(sb, KERN_ERR,
"discard not supported by device, disabling");
opts->discard = 0;
}
}
}

/*
* If the value of "clu" is 0, it means cluster 2 which is the first cluster of
* the cluster heap.
*/
unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
{
unsigned int i, map_i, map_b, ent_idx;
unsigned int clu_base, clu_free;
unsigned char k, clu_mask;
struct exfat_sb_info *sbi = EXFAT_SB(sb);

WARN_ON(clu < EXFAT_FIRST_CLUSTER);
ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));
clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);

map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);

for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
i += BITS_PER_BYTE) {
k = *(sbi->vol_amap[map_i]->b_data + map_b);
if (clu_mask > 0) {
k |= clu_mask;
clu_mask = 0;
}
if (k < 0xFF) {
clu_free = clu_base + free_bit[k];
if (clu_free < sbi->num_clusters)
return clu_free;
}
clu_base += BITS_PER_BYTE;

if (++map_b >= sb->s_blocksize ||
clu_base >= sbi->num_clusters) {
if (++map_i >= sbi->map_sectors) {
clu_base = EXFAT_FIRST_CLUSTER;
map_i = 0;
}
map_b = 0;
}
}

return EXFAT_EOF_CLUSTER;
}

int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
{
struct exfat_sb_info *sbi = EXFAT_SB(sb);
unsigned int count = 0;
unsigned int i, map_i = 0, map_b = 0;
unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;
unsigned char clu_bits;
const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};

total_clus &= ~last_mask;
for (i = 0; i < total_clus; i += BITS_PER_BYTE) {
clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
count += used_bit[clu_bits];
if (++map_b >= (unsigned int)sb->s_blocksize) {
map_i++;
map_b = 0;
}
}

if (last_mask) {
clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
clu_bits &= last_bit_mask[last_mask];
count += used_bit[clu_bits];
}

*ret_count = count;
return 0;
}

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