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|
/*
* linux/fs/sysv/truncate.c
*
* minix/truncate.c
* Copyright (C) 1991, 1992 Linus Torvalds
*
* coh/truncate.c
* Copyright (C) 1993 Pascal Haible, Bruno Haible
*
* sysv/truncate.c
* Copyright (C) 1993 Bruno Haible
*/
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/sysv_fs.h>
#include <linux/stat.h>
/* Linus' implementation of truncate.
* It doesn't need locking because it can tell from looking at bh->b_count
* whether a given block is in use elsewhere.
*/
/*
* 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.
*/
/* We throw away any data beyond inode->i_size. */
static int trunc_direct(struct inode * inode)
{
struct super_block * sb;
unsigned int i;
unsigned long * p;
unsigned long block;
struct buffer_head * bh;
int retry = 0;
sb = inode->i_sb;
repeat:
for (i = ((unsigned long) inode->i_size + sb->sv_block_size_1) >> sb->sv_block_size_bits; i < 10; i++) {
p = inode->u.sysv_i.i_data + i;
block = *p;
if (!block)
continue;
bh = sv_get_hash_table(sb, inode->i_dev, block);
if ((i << sb->sv_block_size_bits) < inode->i_size) {
brelse(bh);
goto repeat;
}
if ((bh && bh->b_count != 1) || (block != *p)) {
retry = 1;
brelse(bh);
continue;
}
*p = 0;
mark_inode_dirty(inode);
brelse(bh);
sysv_free_block(sb,block);
}
return retry;
}
static int trunc_indirect(struct inode * inode, unsigned long offset, unsigned long * p, int convert, unsigned char * dirt)
{
unsigned long indtmp, indblock;
struct super_block * sb;
struct buffer_head * indbh;
unsigned int i;
sysv_zone_t * ind;
unsigned long tmp, block;
struct buffer_head * bh;
int retry = 0;
indblock = indtmp = *p;
if (convert)
indblock = from_coh_ulong(indblock);
if (!indblock)
return 0;
sb = inode->i_sb;
indbh = sv_bread(sb, inode->i_dev, indblock);
if (indtmp != *p) {
brelse(indbh);
return 1;
}
if (!indbh) {
*p = 0;
*dirt = 1;
return 0;
}
repeat:
if (inode->i_size < offset)
i = 0;
else
i = (inode->i_size - offset + sb->sv_block_size_1) >> sb->sv_block_size_bits;
for (; i < sb->sv_ind_per_block; i++) {
ind = ((sysv_zone_t *) indbh->b_data) + i;
block = tmp = *ind;
if (sb->sv_convert)
block = from_coh_ulong(block);
if (!block)
continue;
bh = sv_get_hash_table(sb, inode->i_dev, block);
if ((i << sb->sv_block_size_bits) + offset < inode->i_size) {
brelse(bh);
goto repeat;
}
if ((bh && bh->b_count != 1) || (tmp != *ind)) {
retry = 1;
brelse(bh);
continue;
}
*ind = 0;
mark_buffer_dirty(indbh, 1);
brelse(bh);
sysv_free_block(sb,block);
}
for (i = 0; i < sb->sv_ind_per_block; i++)
if (((sysv_zone_t *) indbh->b_data)[i])
goto done;
if ((indbh->b_count != 1) || (indtmp != *p)) {
brelse(indbh);
return 1;
}
*p = 0;
*dirt = 1;
sysv_free_block(sb,indblock);
done:
brelse(indbh);
return retry;
}
static int trunc_dindirect(struct inode * inode, unsigned long offset, unsigned long * p, int convert, unsigned char * dirt)
{
unsigned long indtmp, indblock;
struct super_block * sb;
struct buffer_head * indbh;
unsigned int i;
sysv_zone_t * ind;
unsigned long tmp, block;
int retry = 0;
indblock = indtmp = *p;
if (convert)
indblock = from_coh_ulong(indblock);
if (!indblock)
return 0;
sb = inode->i_sb;
indbh = sv_bread(sb, inode->i_dev, indblock);
if (indtmp != *p) {
brelse(indbh);
return 1;
}
if (!indbh) {
*p = 0;
*dirt = 1;
return 0;
}
if (inode->i_size < offset)
i = 0;
else
i = (inode->i_size - offset + sb->sv_ind_per_block_block_size_1) >> sb->sv_ind_per_block_block_size_bits;
for (; i < sb->sv_ind_per_block; i++) {
unsigned char dirty = 0;
ind = ((sysv_zone_t *) indbh->b_data) + i;
block = tmp = *ind;
if (sb->sv_convert)
block = from_coh_ulong(block);
if (!block)
continue;
retry |= trunc_indirect(inode,offset+(i<<sb->sv_ind_per_block_bits),ind,sb->sv_convert,&dirty);
if (dirty)
mark_buffer_dirty(indbh, 1);
}
for (i = 0; i < sb->sv_ind_per_block; i++)
if (((sysv_zone_t *) indbh->b_data)[i])
goto done;
if ((indbh->b_count != 1) || (indtmp != *p)) {
brelse(indbh);
return 1;
}
*p = 0;
*dirt = 1;
sysv_free_block(sb,indblock);
done:
brelse(indbh);
return retry;
}
static int trunc_tindirect(struct inode * inode, unsigned long offset, unsigned long * p, int convert, unsigned char * dirt)
{
unsigned long indtmp, indblock;
struct super_block * sb;
struct buffer_head * indbh;
unsigned int i;
sysv_zone_t * ind;
unsigned long tmp, block;
int retry = 0;
indblock = indtmp = *p;
if (convert)
indblock = from_coh_ulong(indblock);
if (!indblock)
return 0;
sb = inode->i_sb;
indbh = sv_bread(sb, inode->i_dev, indblock);
if (indtmp != *p) {
brelse(indbh);
return 1;
}
if (!indbh) {
*p = 0;
*dirt = 1;
return 0;
}
if (inode->i_size < offset)
i = 0;
else
i = (inode->i_size - offset + sb->sv_ind_per_block_2_block_size_1) >> sb->sv_ind_per_block_2_block_size_bits;
for (; i < sb->sv_ind_per_block; i++) {
unsigned char dirty = 0;
ind = ((sysv_zone_t *) indbh->b_data) + i;
block = tmp = *ind;
if (sb->sv_convert)
block = from_coh_ulong(block);
if (!block)
continue;
retry |= trunc_dindirect(inode,offset+(i<<sb->sv_ind_per_block_2_bits),ind,sb->sv_convert,&dirty);
if (dirty)
mark_buffer_dirty(indbh, 1);
}
for (i = 0; i < sb->sv_ind_per_block; i++)
if (((sysv_zone_t *) indbh->b_data)[i])
goto done;
if ((indbh->b_count != 1) || (indtmp != *p)) {
brelse(indbh);
return 1;
}
*p = 0;
*dirt = 1;
sysv_free_block(sb,indblock);
done:
brelse(indbh);
return retry;
}
static int trunc_all(struct inode * inode)
{
struct super_block * sb;
char dirty;
sb = inode->i_sb;
return trunc_direct(inode)
| trunc_indirect(inode,sb->sv_ind0_size,&inode->u.sysv_i.i_data[10],0,&dirty)
| trunc_dindirect(inode,sb->sv_ind1_size,&inode->u.sysv_i.i_data[11],0,&dirty)
| trunc_tindirect(inode,sb->sv_ind2_size,&inode->u.sysv_i.i_data[12],0,&dirty);
}
void sysv_truncate(struct inode * inode)
{
/* If this is called from sysv_put_inode, we needn't worry about
* races as we are just losing the last reference to the inode.
* If this is called from another place, let's hope it's a regular
* file.
* Truncating symbolic links is strange. We assume we don't truncate
* a directory we are just modifying. We ensure we don't truncate
* a regular file we are just writing to, by use of a lock.
*/
if (S_ISLNK(inode->i_mode))
printk("sysv_truncate: truncating symbolic link\n");
else if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
return;
while (trunc_all(inode)) {
current->counter = 0;
schedule();
}
inode->i_mtime = inode->i_ctime = CURRENT_TIME;
mark_inode_dirty(inode);
}
|
