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/*
* linux/fs/fat/buffer.c
*
*
*/
#include <linux/mm.h>
#include <linux/malloc.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/fat_cvf.h>
#if 0
# define PRINTK(x) printk x
#else
# define PRINTK(x)
#endif
struct buffer_head *fat_bread(struct super_block *sb, int block)
{
return MSDOS_SB(sb)->cvf_format->cvf_bread(sb,block);
}
struct buffer_head *fat_getblk(struct super_block *sb, int block)
{
return MSDOS_SB(sb)->cvf_format->cvf_getblk(sb,block);
}
void fat_brelse (struct super_block *sb, struct buffer_head *bh)
{
if (bh)
MSDOS_SB(sb)->cvf_format->cvf_brelse(sb,bh);
}
void fat_mark_buffer_dirty (
struct super_block *sb,
struct buffer_head *bh)
{
MSDOS_SB(sb)->cvf_format->cvf_mark_buffer_dirty(sb,bh);
}
void fat_set_uptodate (
struct super_block *sb,
struct buffer_head *bh,
int val)
{
MSDOS_SB(sb)->cvf_format->cvf_set_uptodate(sb,bh,val);
}
int fat_is_uptodate(struct super_block *sb, struct buffer_head *bh)
{
return MSDOS_SB(sb)->cvf_format->cvf_is_uptodate(sb,bh);
}
void fat_ll_rw_block (
struct super_block *sb,
int opr,
int nbreq,
struct buffer_head *bh[32])
{
MSDOS_SB(sb)->cvf_format->cvf_ll_rw_block(sb,opr,nbreq,bh);
}
struct buffer_head *default_fat_bread(struct super_block *sb, int block)
{
return bread (sb->s_dev,block,512);
}
struct buffer_head *default_fat_getblk(struct super_block *sb, int block)
{
return getblk (sb->s_dev,block,512);
}
void default_fat_brelse(struct super_block *sb, struct buffer_head *bh)
{
brelse (bh);
}
void default_fat_mark_buffer_dirty (
struct super_block *sb,
struct buffer_head *bh)
{
mark_buffer_dirty (bh);
}
void default_fat_set_uptodate (
struct super_block *sb,
struct buffer_head *bh,
int val)
{
mark_buffer_uptodate(bh, val);
}
int default_fat_is_uptodate (struct super_block *sb, struct buffer_head *bh)
{
return buffer_uptodate(bh);
}
void default_fat_ll_rw_block (
struct super_block *sb,
int opr,
int nbreq,
struct buffer_head *bh[32])
{
ll_rw_block(opr,nbreq,bh);
}
struct buffer_head *bigblock_fat_bread (
struct super_block *sb,
int block)
{
struct buffer_head *ret = NULL;
struct buffer_head *real;
if (sb->s_blocksize == 1024){
real = bread (sb->s_dev,block>>1,1024);
} else {
real = bread (sb->s_dev,block>>2,2048);
}
if (real != NULL) {
ret = (struct buffer_head *)
kmalloc (sizeof(struct buffer_head), GFP_KERNEL);
if (ret != NULL) {
/* #Specification: msdos / strategy / special device / dummy blocks
* Many special device (Scsi optical disk for one) use
* larger hardware sector size. This allows for higher
* capacity.
* Most of the time, the MS-DOS filesystem that sits
* on this device is totally unaligned. It use logically
* 512 bytes sector size, with logical sector starting
* in the middle of a hardware block. The bad news is
* that a hardware sector may hold data own by two
* different files. This means that the hardware sector
* must be read, patch and written almost all the time.
* Needless to say that it kills write performance
* on all OS.
* Internally the linux msdos fs is using 512 bytes
* logical sector. When accessing such a device, we
* allocate dummy buffer cache blocks, that we stuff
* with the information of a real one (1k large).
* This strategy is used to hide this difference to
* the core of the msdos fs. The slowdown is not
* hidden though!
*/
/*
* The memset is there only to catch errors. The msdos
* fs is only using b_data
*/
memset (ret,0,sizeof(*ret));
ret->b_data = real->b_data;
if (sb->s_blocksize == 2048) {
if (block & 3) ret->b_data += (block & 3) << 9;
}else{
if (block & 1) ret->b_data += 512;
}
ret->b_next = real;
}else{
brelse (real);
}
}
return ret;
}
void bigblock_fat_brelse (
struct super_block *sb,
struct buffer_head *bh)
{
brelse (bh->b_next);
/*
* We can free the dummy because a new one is allocated at
* each fat_getblk() and fat_bread().
*/
kfree (bh);
}
void bigblock_fat_mark_buffer_dirty (
struct super_block *sb,
struct buffer_head *bh)
{
mark_buffer_dirty (bh->b_next);
}
void bigblock_fat_set_uptodate (
struct super_block *sb,
struct buffer_head *bh,
int val)
{
mark_buffer_uptodate(bh->b_next, val);
}
int bigblock_fat_is_uptodate (
struct super_block *sb,
struct buffer_head *bh)
{
return buffer_uptodate(bh->b_next);
}
void bigblock_fat_ll_rw_block (
struct super_block *sb,
int opr,
int nbreq,
struct buffer_head *bh[32])
{
struct buffer_head *tmp[32];
int i;
for (i=0; i<nbreq; i++)
tmp[i] = bh[i]->b_next;
ll_rw_block(opr,nbreq,tmp);
}
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