forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
407 lines
10 KiB
407 lines
10 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
|
* linux/fs/adfs/map.c |
|
* |
|
* Copyright (C) 1997-2002 Russell King |
|
*/ |
|
#include <linux/slab.h> |
|
#include <linux/statfs.h> |
|
#include <asm/unaligned.h> |
|
#include "adfs.h" |
|
|
|
/* |
|
* The ADFS map is basically a set of sectors. Each sector is called a |
|
* zone which contains a bitstream made up of variable sized fragments. |
|
* Each bit refers to a set of bytes in the filesystem, defined by |
|
* log2bpmb. This may be larger or smaller than the sector size, but |
|
* the overall size it describes will always be a round number of |
|
* sectors. A fragment id is always idlen bits long. |
|
* |
|
* < idlen > < n > <1> |
|
* +---------+-------//---------+---+ |
|
* | frag id | 0000....000000 | 1 | |
|
* +---------+-------//---------+---+ |
|
* |
|
* The physical disk space used by a fragment is taken from the start of |
|
* the fragment id up to and including the '1' bit - ie, idlen + n + 1 |
|
* bits. |
|
* |
|
* A fragment id can be repeated multiple times in the whole map for |
|
* large or fragmented files. The first map zone a fragment starts in |
|
* is given by fragment id / ids_per_zone - this allows objects to start |
|
* from any zone on the disk. |
|
* |
|
* Free space is described by a linked list of fragments. Each free |
|
* fragment describes free space in the same way as the other fragments, |
|
* however, the frag id specifies an offset (in map bits) from the end |
|
* of this fragment to the start of the next free fragment. |
|
* |
|
* Objects stored on the disk are allocated object ids (we use these as |
|
* our inode numbers.) Object ids contain a fragment id and an optional |
|
* offset. This allows a directory fragment to contain small files |
|
* associated with that directory. |
|
*/ |
|
|
|
/* |
|
* For the future... |
|
*/ |
|
static DEFINE_RWLOCK(adfs_map_lock); |
|
|
|
/* |
|
* This is fun. We need to load up to 19 bits from the map at an |
|
* arbitrary bit alignment. (We're limited to 19 bits by F+ version 2). |
|
*/ |
|
#define GET_FRAG_ID(_map,_start,_idmask) \ |
|
({ \ |
|
unsigned char *_m = _map + (_start >> 3); \ |
|
u32 _frag = get_unaligned_le32(_m); \ |
|
_frag >>= (_start & 7); \ |
|
_frag & _idmask; \ |
|
}) |
|
|
|
/* |
|
* return the map bit offset of the fragment frag_id in the zone dm. |
|
* Note that the loop is optimised for best asm code - look at the |
|
* output of: |
|
* gcc -D__KERNEL__ -O2 -I../../include -o - -S map.c |
|
*/ |
|
static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen, |
|
const u32 frag_id, unsigned int *offset) |
|
{ |
|
const unsigned int endbit = dm->dm_endbit; |
|
const u32 idmask = (1 << idlen) - 1; |
|
unsigned char *map = dm->dm_bh->b_data; |
|
unsigned int start = dm->dm_startbit; |
|
unsigned int freelink, fragend; |
|
u32 frag; |
|
|
|
frag = GET_FRAG_ID(map, 8, idmask & 0x7fff); |
|
freelink = frag ? 8 + frag : 0; |
|
|
|
do { |
|
frag = GET_FRAG_ID(map, start, idmask); |
|
|
|
fragend = find_next_bit_le(map, endbit, start + idlen); |
|
if (fragend >= endbit) |
|
goto error; |
|
|
|
if (start == freelink) { |
|
freelink += frag & 0x7fff; |
|
} else if (frag == frag_id) { |
|
unsigned int length = fragend + 1 - start; |
|
|
|
if (*offset < length) |
|
return start + *offset; |
|
*offset -= length; |
|
} |
|
|
|
start = fragend + 1; |
|
} while (start < endbit); |
|
return -1; |
|
|
|
error: |
|
printk(KERN_ERR "adfs: oversized fragment 0x%x at 0x%x-0x%x\n", |
|
frag, start, fragend); |
|
return -1; |
|
} |
|
|
|
/* |
|
* Scan the free space map, for this zone, calculating the total |
|
* number of map bits in each free space fragment. |
|
* |
|
* Note: idmask is limited to 15 bits [3.2] |
|
*/ |
|
static unsigned int |
|
scan_free_map(struct adfs_sb_info *asb, struct adfs_discmap *dm) |
|
{ |
|
const unsigned int endbit = dm->dm_endbit; |
|
const unsigned int idlen = asb->s_idlen; |
|
const unsigned int frag_idlen = idlen <= 15 ? idlen : 15; |
|
const u32 idmask = (1 << frag_idlen) - 1; |
|
unsigned char *map = dm->dm_bh->b_data; |
|
unsigned int start = 8, fragend; |
|
u32 frag; |
|
unsigned long total = 0; |
|
|
|
/* |
|
* get fragment id |
|
*/ |
|
frag = GET_FRAG_ID(map, start, idmask); |
|
|
|
/* |
|
* If the freelink is null, then no free fragments |
|
* exist in this zone. |
|
*/ |
|
if (frag == 0) |
|
return 0; |
|
|
|
do { |
|
start += frag; |
|
|
|
frag = GET_FRAG_ID(map, start, idmask); |
|
|
|
fragend = find_next_bit_le(map, endbit, start + idlen); |
|
if (fragend >= endbit) |
|
goto error; |
|
|
|
total += fragend + 1 - start; |
|
} while (frag >= idlen + 1); |
|
|
|
if (frag != 0) |
|
printk(KERN_ERR "adfs: undersized free fragment\n"); |
|
|
|
return total; |
|
error: |
|
printk(KERN_ERR "adfs: oversized free fragment\n"); |
|
return 0; |
|
} |
|
|
|
static int scan_map(struct adfs_sb_info *asb, unsigned int zone, |
|
const u32 frag_id, unsigned int mapoff) |
|
{ |
|
const unsigned int idlen = asb->s_idlen; |
|
struct adfs_discmap *dm, *dm_end; |
|
int result; |
|
|
|
dm = asb->s_map + zone; |
|
zone = asb->s_map_size; |
|
dm_end = asb->s_map + zone; |
|
|
|
do { |
|
result = lookup_zone(dm, idlen, frag_id, &mapoff); |
|
|
|
if (result != -1) |
|
goto found; |
|
|
|
dm ++; |
|
if (dm == dm_end) |
|
dm = asb->s_map; |
|
} while (--zone > 0); |
|
|
|
return -1; |
|
found: |
|
result -= dm->dm_startbit; |
|
result += dm->dm_startblk; |
|
|
|
return result; |
|
} |
|
|
|
/* |
|
* calculate the amount of free blocks in the map. |
|
* |
|
* n=1 |
|
* total_free = E(free_in_zone_n) |
|
* nzones |
|
*/ |
|
void adfs_map_statfs(struct super_block *sb, struct kstatfs *buf) |
|
{ |
|
struct adfs_sb_info *asb = ADFS_SB(sb); |
|
struct adfs_discrecord *dr = adfs_map_discrecord(asb->s_map); |
|
struct adfs_discmap *dm; |
|
unsigned int total = 0; |
|
unsigned int zone; |
|
|
|
dm = asb->s_map; |
|
zone = asb->s_map_size; |
|
|
|
do { |
|
total += scan_free_map(asb, dm++); |
|
} while (--zone > 0); |
|
|
|
buf->f_blocks = adfs_disc_size(dr) >> sb->s_blocksize_bits; |
|
buf->f_files = asb->s_ids_per_zone * asb->s_map_size; |
|
buf->f_bavail = |
|
buf->f_bfree = signed_asl(total, asb->s_map2blk); |
|
} |
|
|
|
int adfs_map_lookup(struct super_block *sb, u32 frag_id, unsigned int offset) |
|
{ |
|
struct adfs_sb_info *asb = ADFS_SB(sb); |
|
unsigned int zone, mapoff; |
|
int result; |
|
|
|
/* |
|
* map & root fragment is special - it starts in the center of the |
|
* disk. The other fragments start at zone (frag / ids_per_zone) |
|
*/ |
|
if (frag_id == ADFS_ROOT_FRAG) |
|
zone = asb->s_map_size >> 1; |
|
else |
|
zone = frag_id / asb->s_ids_per_zone; |
|
|
|
if (zone >= asb->s_map_size) |
|
goto bad_fragment; |
|
|
|
/* Convert sector offset to map offset */ |
|
mapoff = signed_asl(offset, -asb->s_map2blk); |
|
|
|
read_lock(&adfs_map_lock); |
|
result = scan_map(asb, zone, frag_id, mapoff); |
|
read_unlock(&adfs_map_lock); |
|
|
|
if (result > 0) { |
|
unsigned int secoff; |
|
|
|
/* Calculate sector offset into map block */ |
|
secoff = offset - signed_asl(mapoff, asb->s_map2blk); |
|
return secoff + signed_asl(result, asb->s_map2blk); |
|
} |
|
|
|
adfs_error(sb, "fragment 0x%04x at offset %d not found in map", |
|
frag_id, offset); |
|
return 0; |
|
|
|
bad_fragment: |
|
adfs_error(sb, "invalid fragment 0x%04x (zone = %d, max = %d)", |
|
frag_id, zone, asb->s_map_size); |
|
return 0; |
|
} |
|
|
|
static unsigned char adfs_calczonecheck(struct super_block *sb, unsigned char *map) |
|
{ |
|
unsigned int v0, v1, v2, v3; |
|
int i; |
|
|
|
v0 = v1 = v2 = v3 = 0; |
|
for (i = sb->s_blocksize - 4; i; i -= 4) { |
|
v0 += map[i] + (v3 >> 8); |
|
v3 &= 0xff; |
|
v1 += map[i + 1] + (v0 >> 8); |
|
v0 &= 0xff; |
|
v2 += map[i + 2] + (v1 >> 8); |
|
v1 &= 0xff; |
|
v3 += map[i + 3] + (v2 >> 8); |
|
v2 &= 0xff; |
|
} |
|
v0 += v3 >> 8; |
|
v1 += map[1] + (v0 >> 8); |
|
v2 += map[2] + (v1 >> 8); |
|
v3 += map[3] + (v2 >> 8); |
|
|
|
return v0 ^ v1 ^ v2 ^ v3; |
|
} |
|
|
|
static int adfs_checkmap(struct super_block *sb, struct adfs_discmap *dm) |
|
{ |
|
unsigned char crosscheck = 0, zonecheck = 1; |
|
int i; |
|
|
|
for (i = 0; i < ADFS_SB(sb)->s_map_size; i++) { |
|
unsigned char *map; |
|
|
|
map = dm[i].dm_bh->b_data; |
|
|
|
if (adfs_calczonecheck(sb, map) != map[0]) { |
|
adfs_error(sb, "zone %d fails zonecheck", i); |
|
zonecheck = 0; |
|
} |
|
crosscheck ^= map[3]; |
|
} |
|
if (crosscheck != 0xff) |
|
adfs_error(sb, "crosscheck != 0xff"); |
|
return crosscheck == 0xff && zonecheck; |
|
} |
|
|
|
/* |
|
* Layout the map - the first zone contains a copy of the disc record, |
|
* and the last zone must be limited to the size of the filesystem. |
|
*/ |
|
static void adfs_map_layout(struct adfs_discmap *dm, unsigned int nzones, |
|
struct adfs_discrecord *dr) |
|
{ |
|
unsigned int zone, zone_size; |
|
u64 size; |
|
|
|
zone_size = (8 << dr->log2secsize) - le16_to_cpu(dr->zone_spare); |
|
|
|
dm[0].dm_bh = NULL; |
|
dm[0].dm_startblk = 0; |
|
dm[0].dm_startbit = 32 + ADFS_DR_SIZE_BITS; |
|
dm[0].dm_endbit = 32 + zone_size; |
|
|
|
for (zone = 1; zone < nzones; zone++) { |
|
dm[zone].dm_bh = NULL; |
|
dm[zone].dm_startblk = zone * zone_size - ADFS_DR_SIZE_BITS; |
|
dm[zone].dm_startbit = 32; |
|
dm[zone].dm_endbit = 32 + zone_size; |
|
} |
|
|
|
size = adfs_disc_size(dr) >> dr->log2bpmb; |
|
size -= (nzones - 1) * zone_size - ADFS_DR_SIZE_BITS; |
|
dm[nzones - 1].dm_endbit = 32 + size; |
|
} |
|
|
|
static int adfs_map_read(struct adfs_discmap *dm, struct super_block *sb, |
|
unsigned int map_addr, unsigned int nzones) |
|
{ |
|
unsigned int zone; |
|
|
|
for (zone = 0; zone < nzones; zone++) { |
|
dm[zone].dm_bh = sb_bread(sb, map_addr + zone); |
|
if (!dm[zone].dm_bh) |
|
return -EIO; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static void adfs_map_relse(struct adfs_discmap *dm, unsigned int nzones) |
|
{ |
|
unsigned int zone; |
|
|
|
for (zone = 0; zone < nzones; zone++) |
|
brelse(dm[zone].dm_bh); |
|
} |
|
|
|
struct adfs_discmap *adfs_read_map(struct super_block *sb, struct adfs_discrecord *dr) |
|
{ |
|
struct adfs_sb_info *asb = ADFS_SB(sb); |
|
struct adfs_discmap *dm; |
|
unsigned int map_addr, zone_size, nzones; |
|
int ret; |
|
|
|
nzones = dr->nzones | dr->nzones_high << 8; |
|
zone_size = (8 << dr->log2secsize) - le16_to_cpu(dr->zone_spare); |
|
|
|
asb->s_idlen = dr->idlen; |
|
asb->s_map_size = nzones; |
|
asb->s_map2blk = dr->log2bpmb - dr->log2secsize; |
|
asb->s_log2sharesize = dr->log2sharesize; |
|
asb->s_ids_per_zone = zone_size / (asb->s_idlen + 1); |
|
|
|
map_addr = (nzones >> 1) * zone_size - |
|
((nzones > 1) ? ADFS_DR_SIZE_BITS : 0); |
|
map_addr = signed_asl(map_addr, asb->s_map2blk); |
|
|
|
dm = kmalloc_array(nzones, sizeof(*dm), GFP_KERNEL); |
|
if (dm == NULL) { |
|
adfs_error(sb, "not enough memory"); |
|
return ERR_PTR(-ENOMEM); |
|
} |
|
|
|
adfs_map_layout(dm, nzones, dr); |
|
|
|
ret = adfs_map_read(dm, sb, map_addr, nzones); |
|
if (ret) { |
|
adfs_error(sb, "unable to read map"); |
|
goto error_free; |
|
} |
|
|
|
if (adfs_checkmap(sb, dm)) |
|
return dm; |
|
|
|
adfs_error(sb, "map corrupted"); |
|
|
|
error_free: |
|
adfs_map_relse(dm, nzones); |
|
kfree(dm); |
|
return ERR_PTR(-EIO); |
|
} |
|
|
|
void adfs_free_map(struct super_block *sb) |
|
{ |
|
struct adfs_sb_info *asb = ADFS_SB(sb); |
|
|
|
adfs_map_relse(asb->s_map, asb->s_map_size); |
|
kfree(asb->s_map); |
|
}
|
|
|