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DEFINITIONS
This source file includes following definitions.
- get_chunk
- sysv_free_block
- sysv_new_block
- sysv_count_free_blocks
/*
* linux/fs/sysv/balloc.c
*
* minix/bitmap.c
* Copyright (C) 1991, 1992 Linus Torvalds
*
* ext/freelists.c
* Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
*
* xenix/alloc.c
* Copyright (C) 1992 Doug Evans
*
* coh/alloc.c
* Copyright (C) 1993 Pascal Haible, Bruno Haible
*
* sysv/balloc.c
* Copyright (C) 1993 Bruno Haible
*
* This file contains code for allocating/freeing blocks.
*/
#include <linux/buffer_head.h>
#include <linux/string.h>
#include "sysv.h"
/* We don't trust the value of
sb->sv_sbd2->s_tfree = *sb->sv_free_blocks
but we nevertheless keep it up to date. */
static inline sysv_zone_t *get_chunk(struct super_block *sb, struct buffer_head *bh)
{
char *bh_data = bh->b_data;
if (SYSV_SB(sb)->s_type == FSTYPE_SYSV4)
return (sysv_zone_t*)(bh_data+4);
else
return (sysv_zone_t*)(bh_data+2);
}
/* NOTE NOTE NOTE: nr is a block number _as_ _stored_ _on_ _disk_ */
void sysv_free_block(struct super_block * sb, sysv_zone_t nr)
{
struct sysv_sb_info * sbi = SYSV_SB(sb);
struct buffer_head * bh;
sysv_zone_t *blocks = sbi->s_bcache;
unsigned count;
unsigned block = fs32_to_cpu(sbi, nr);
/*
* This code does not work at all for AFS (it has a bitmap
* free list). As AFS is supposed to be read-only no one
* should call this for an AFS filesystem anyway...
*/
if (sbi->s_type == FSTYPE_AFS)
return;
if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
printk("sysv_free_block: trying to free block not in datazone\n");
return;
}
lock_super(sb);
count = fs16_to_cpu(sbi, *sbi->s_bcache_count);
if (count > sbi->s_flc_size) {
printk("sysv_free_block: flc_count > flc_size\n");
unlock_super(sb);
return;
}
/* If the free list head in super-block is full, it is copied
* into this block being freed, ditto if it's completely empty
* (applies only on Coherent).
*/
if (count == sbi->s_flc_size || count == 0) {
block += sbi->s_block_base;
bh = sb_getblk(sb, block);
if (!bh) {
printk("sysv_free_block: getblk() failed\n");
unlock_super(sb);
return;
}
memset(bh->b_data, 0, sb->s_blocksize);
*(__fs16*)bh->b_data = cpu_to_fs16(sbi, count);
memcpy(get_chunk(sb,bh), blocks, count * sizeof(sysv_zone_t));
mark_buffer_dirty(bh);
set_buffer_uptodate(bh);
brelse(bh);
count = 0;
}
sbi->s_bcache[count++] = nr;
*sbi->s_bcache_count = cpu_to_fs16(sbi, count);
fs32_add(sbi, sbi->s_free_blocks, 1);
dirty_sb(sb);
unlock_super(sb);
}
sysv_zone_t sysv_new_block(struct super_block * sb)
{
struct sysv_sb_info *sbi = SYSV_SB(sb);
unsigned int block;
sysv_zone_t nr;
struct buffer_head * bh;
unsigned count;
lock_super(sb);
count = fs16_to_cpu(sbi, *sbi->s_bcache_count);
if (count == 0) /* Applies only to Coherent FS */
goto Enospc;
nr = sbi->s_bcache[--count];
if (nr == 0) /* Applies only to Xenix FS, SystemV FS */
goto Enospc;
block = fs32_to_cpu(sbi, nr);
*sbi->s_bcache_count = cpu_to_fs16(sbi, count);
if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
printk("sysv_new_block: new block %d is not in data zone\n",
block);
goto Enospc;
}
if (count == 0) { /* the last block continues the free list */
unsigned count;
block += sbi->s_block_base;
if (!(bh = sb_bread(sb, block))) {
printk("sysv_new_block: cannot read free-list block\n");
/* retry this same block next time */
*sbi->s_bcache_count = cpu_to_fs16(sbi, 1);
goto Enospc;
}
count = fs16_to_cpu(sbi, *(__fs16*)bh->b_data);
if (count > sbi->s_flc_size) {
printk("sysv_new_block: free-list block with >flc_size entries\n");
brelse(bh);
goto Enospc;
}
*sbi->s_bcache_count = cpu_to_fs16(sbi, count);
memcpy(sbi->s_bcache, get_chunk(sb, bh),
count * sizeof(sysv_zone_t));
brelse(bh);
}
/* Now the free list head in the superblock is valid again. */
fs32_add(sbi, sbi->s_free_blocks, -1);
dirty_sb(sb);
unlock_super(sb);
return nr;
Enospc:
unlock_super(sb);
return 0;
}
unsigned long sysv_count_free_blocks(struct super_block * sb)
{
struct sysv_sb_info * sbi = SYSV_SB(sb);
int sb_count;
int count;
struct buffer_head * bh = NULL;
sysv_zone_t *blocks;
unsigned block;
int n;
/*
* This code does not work at all for AFS (it has a bitmap
* free list). As AFS is supposed to be read-only we just
* lie and say it has no free block at all.
*/
if (sbi->s_type == FSTYPE_AFS)
return 0;
lock_super(sb);
sb_count = fs32_to_cpu(sbi, *sbi->s_free_blocks);
if (0)
goto trust_sb;
/* this causes a lot of disk traffic ... */
count = 0;
n = fs16_to_cpu(sbi, *sbi->s_bcache_count);
blocks = sbi->s_bcache;
while (1) {
sysv_zone_t zone;
if (n > sbi->s_flc_size)
goto E2big;
zone = 0;
while (n && (zone = blocks[--n]) != 0)
count++;
if (zone == 0)
break;
block = fs32_to_cpu(sbi, zone);
if (bh)
brelse(bh);
if (block < sbi->s_firstdatazone || block >= sbi->s_nzones)
goto Einval;
block += sbi->s_block_base;
bh = sb_bread(sb, block);
if (!bh)
goto Eio;
n = fs16_to_cpu(sbi, *(__fs16*)bh->b_data);
blocks = get_chunk(sb, bh);
}
if (bh)
brelse(bh);
if (count != sb_count)
goto Ecount;
done:
unlock_super(sb);
return count;
Einval:
printk("sysv_count_free_blocks: new block %d is not in data zone\n",
block);
goto trust_sb;
Eio:
printk("sysv_count_free_blocks: cannot read free-list block\n");
goto trust_sb;
E2big:
printk("sysv_count_free_blocks: >flc_size entries in free-list block\n");
if (bh)
brelse(bh);
trust_sb:
count = sb_count;
goto done;
Ecount:
printk("sysv_count_free_blocks: free block count was %d, "
"correcting to %d\n", sb_count, count);
if (!(sb->s_flags & MS_RDONLY)) {
*sbi->s_free_blocks = cpu_to_fs32(sbi, count);
dirty_sb(sb);
}
goto done;
}