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/*
* linux/fs/xiafs/truncate.c
*
* Copyright (C) Q. Frank Xia, 1993.
*
* Based on Linus' minix/truncate.c
* Copyright (C) Linus Torvalds, 1991, 1992.
*
* This software may be redistributed per Linux Copyright.
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/xia_fs.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include "xiafs_mac.h"
/*
* Linus' comment:
*
* 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.
*/
#define DT_ZONE ((inode->i_size + XIAFS_ZSIZE(inode->i_sb) - 1) \
>> XIAFS_ZSIZE_BITS(inode->i_sb) )
static int trunc_direct(struct inode * inode)
{
u_long * lp;
struct buffer_head * bh;
int i, tmp;
int retry = 0;
repeat:
for (i = DT_ZONE ; i < 8 ; i++) {
if (i < DT_ZONE)
goto repeat;
lp=i + inode->u.xiafs_i.i_zone;
if (!(tmp = *lp))
continue;
bh = getblk(inode->i_dev, tmp, XIAFS_ZSIZE(inode->i_sb));
if (i < DT_ZONE) {
brelse(bh);
goto repeat;
}
if ((bh && bh->b_count != 1) || tmp != *lp)
retry = 1;
else {
*lp = 0;
inode->i_dirt = 1;
inode->i_blocks-=2 << XIAFS_ZSHIFT(inode->i_sb);
xiafs_free_zone(inode->i_sb, tmp);
}
brelse(bh);
}
return retry;
}
static int trunc_indirect(struct inode * inode, int addr_off, u_long * lp)
{
#define INDT_ZONE (DT_ZONE - addr_off)
struct buffer_head * bh, * ind_bh;
int i, tmp;
u_long * indp;
int retry = 0;
if ( !(tmp=*lp) )
return 0;
ind_bh = bread(inode->i_dev, tmp, XIAFS_ZSIZE(inode->i_sb));
if (tmp != *lp) {
brelse(ind_bh);
return 1;
}
if (!ind_bh) {
*lp = 0;
return 0;
}
repeat:
for (i = INDT_ZONE<0?0:INDT_ZONE; i < XIAFS_ADDRS_PER_Z(inode->i_sb); i++) {
if (i < INDT_ZONE)
goto repeat;
indp = i+(u_long *) ind_bh->b_data;
if (!(tmp=*indp))
continue;
bh = getblk(inode->i_dev, tmp, XIAFS_ZSIZE(inode->i_sb));
if (i < INDT_ZONE) {
brelse(bh);
goto repeat;
}
if ((bh && bh->b_count != 1) || tmp != *indp)
retry = 1;
else {
*indp = 0;
ind_bh->b_dirt = 1;
inode->i_blocks-= 2 << XIAFS_ZSHIFT(inode->i_sb);
xiafs_free_zone(inode->i_sb, tmp);
}
brelse(bh);
}
indp = (u_long *) ind_bh->b_data;
for (i = 0; i < XIAFS_ADDRS_PER_Z(inode->i_sb) && !(*indp++); i++) ;
if (i >= XIAFS_ADDRS_PER_Z(inode->i_sb)) {
if (ind_bh->b_count != 1)
retry = 1;
else {
tmp = *lp;
*lp = 0;
inode->i_blocks-= 2 << XIAFS_ZSHIFT(inode->i_sb);
xiafs_free_zone(inode->i_sb, tmp);
}
}
brelse(ind_bh);
return retry;
}
static int trunc_dindirect(struct inode * inode)
{
#define DINDT_ZONE \
((DT_ZONE-XIAFS_ADDRS_PER_Z(inode->i_sb)-8)>>XIAFS_ADDRS_PER_Z_BITS(inode->i_sb))
int i, tmp;
struct buffer_head * dind_bh;
u_long * dindp, * lp;
int retry = 0;
lp = &(inode->u.xiafs_i.i_dind_zone);
if (!(tmp = *lp))
return 0;
dind_bh = bread(inode->i_dev, tmp, XIAFS_ZSIZE(inode->i_sb));
if (tmp != *lp) {
brelse(dind_bh);
return 1;
}
if (!dind_bh) {
*lp = 0;
return 0;
}
repeat:
for (i=DINDT_ZONE<0?0:DINDT_ZONE ; i < XIAFS_ADDRS_PER_Z(inode->i_sb) ; i ++) {
if (i < DINDT_ZONE)
goto repeat;
dindp = i+(u_long *) dind_bh->b_data;
retry |= trunc_indirect(inode,
8+((1+i)<<XIAFS_ADDRS_PER_Z_BITS(inode->i_sb)),
dindp);
dind_bh->b_dirt = 1;
}
dindp = (u_long *) dind_bh->b_data;
for (i = 0; i < XIAFS_ADDRS_PER_Z(inode->i_sb) && !(*dindp++); i++);
if (i >= XIAFS_ADDRS_PER_Z(inode->i_sb)) {
if (dind_bh->b_count != 1)
retry = 1;
else {
tmp = *lp;
*lp = 0;
inode->i_dirt = 1;
inode->i_blocks-=2 << XIAFS_ZSHIFT(inode->i_sb);
xiafs_free_zone(inode->i_sb, tmp);
}
}
brelse(dind_bh);
return retry;
}
void xiafs_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, 8, &(inode->u.xiafs_i.i_ind_zone));
retry |= trunc_dindirect(inode);
if (!retry)
break;
current->counter = 0;
schedule();
}
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
inode->i_dirt = 1;
}