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/*
* linux/fs/truncate.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/minix_fs.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
/*
* Truncate has the most races in the whole filesystem: coding it is
* a pain in the a**. Especially as I don't do any locking...
*
* The code may look a bit weird, but that's just because I've tried to
* handle things like file-size changes in a somewhat graceful manner.
* Anyway, truncating a file at the same time somebody else writes to it
* is likely to result in pretty weird behaviour...
*
* The new code handles normal truncates (size = 0) as well as the more
* general case (size = XXX). I hope.
*/
static int trunc_direct(struct inode * inode)
{
unsigned short * p;
struct buffer_head * bh;
int i, tmp;
int retry = 0;
#define DIRECT_BLOCK ((inode->i_size + 1023) >> 10)
repeat:
for (i = DIRECT_BLOCK ; i < 7 ; i++) {
p = i + inode->u.minix_i.i_data;
if (!(tmp = *p))
continue;
bh = get_hash_table(inode->i_dev,tmp,BLOCK_SIZE);
if (i < DIRECT_BLOCK) {
brelse(bh);
goto repeat;
}
if ((bh && bh->b_count != 1) || tmp != *p) {
retry = 1;
brelse(bh);
continue;
}
*p = 0;
inode->i_dirt = 1;
brelse(bh);
minix_free_block(inode->i_sb,tmp);
}
return retry;
}
static int trunc_indirect(struct inode * inode, int offset, unsigned short * p)
{
struct buffer_head * bh;
int i, tmp;
struct buffer_head * ind_bh;
unsigned short * ind;
int retry = 0;
#define INDIRECT_BLOCK (DIRECT_BLOCK-offset)
tmp = *p;
if (!tmp)
return 0;
ind_bh = bread(inode->i_dev, tmp, BLOCK_SIZE);
if (tmp != *p) {
brelse(ind_bh);
return 1;
}
if (!ind_bh) {
*p = 0;
return 0;
}
repeat:
for (i = INDIRECT_BLOCK ; i < 512 ; i++) {
if (i < 0)
i = 0;
if (i < INDIRECT_BLOCK)
goto repeat;
ind = i+(unsigned short *) ind_bh->b_data;
tmp = *ind;
if (!tmp)
continue;
bh = get_hash_table(inode->i_dev,tmp,BLOCK_SIZE);
if (i < INDIRECT_BLOCK) {
brelse(bh);
goto repeat;
}
if ((bh && bh->b_count != 1) || tmp != *ind) {
retry = 1;
brelse(bh);
continue;
}
*ind = 0;
ind_bh->b_dirt = 1;
brelse(bh);
minix_free_block(inode->i_sb,tmp);
}
ind = (unsigned short *) ind_bh->b_data;
for (i = 0; i < 512; i++)
if (*(ind++))
break;
if (i >= 512)
if (ind_bh->b_count != 1)
retry = 1;
else {
tmp = *p;
*p = 0;
minix_free_block(inode->i_sb,tmp);
}
brelse(ind_bh);
return retry;
}
static int trunc_dindirect(struct inode * inode)
{
int i, tmp;
struct buffer_head * dind_bh;
unsigned short * dind, * p;
int retry = 0;
#define DINDIRECT_BLOCK ((DIRECT_BLOCK-(512+7))>>9)
p = 8 + inode->u.minix_i.i_data;
if (!(tmp = *p))
return 0;
dind_bh = bread(inode->i_dev, tmp, BLOCK_SIZE);
if (tmp != *p) {
brelse(dind_bh);
return 1;
}
if (!dind_bh) {
*p = 0;
return 0;
}
repeat:
for (i = DINDIRECT_BLOCK ; i < 512 ; i ++) {
if (i < 0)
i = 0;
if (i < DINDIRECT_BLOCK)
goto repeat;
dind = i+(unsigned short *) dind_bh->b_data;
retry |= trunc_indirect(inode,7+512+(i<<9),dind);
dind_bh->b_dirt = 1;
}
dind = (unsigned short *) dind_bh->b_data;
for (i = 0; i < 512; i++)
if (*(dind++))
break;
if (i >= 512)
if (dind_bh->b_count != 1)
retry = 1;
else {
tmp = *p;
*p = 0;
inode->i_dirt = 1;
minix_free_block(inode->i_sb,tmp);
}
brelse(dind_bh);
return retry;
}
void minix_truncate(struct inode * inode)
{
int retry;
if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
S_ISLNK(inode->i_mode)))
return;
while (1) {
retry = trunc_direct(inode);
retry |= trunc_indirect(inode,7,inode->u.minix_i.i_data+7);
retry |= trunc_dindirect(inode);
if (!retry)
break;
current->counter = 0;
schedule();
}
inode->i_mtime = inode->i_ctime = CURRENT_TIME;
inode->i_dirt = 1;
}