लिनक्स/linux-0.01.tar/fs/block dev.c
< लिनक्स | linux-0.01.tar
#include <errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#define NR_BLK_DEV ((sizeof (rd_blk))/(sizeof (rd_blk[0])))
int block_write(int dev, long * pos, char * buf, int count)
{
int block = *pos / BLOCK_SIZE;
int offset = *pos % BLOCK_SIZE;
int chars;
int written = 0;
struct buffer_head * bh;
register char * p;
while (count>0) {
bh = bread(dev,block);
if (!bh)
return written?written:-EIO;
chars = (count<BLOCK_SIZE) ? count : BLOCK_SIZE;
p = offset + bh->b_data;
offset = 0;
block++;
*pos += chars;
written += chars;
count -= chars;
while (chars-->0)
*(p++) = get_fs_byte(buf++);
bh->b_dirt = 1;
brelse(bh);
}
return written;
}
int block_read(int dev, unsigned long * pos, char * buf, int count)
{
int block = *pos / BLOCK_SIZE;
int offset = *pos % BLOCK_SIZE;
int chars;
int read = 0;
struct buffer_head * bh;
register char * p;
while (count>0) {
bh = bread(dev,block);
if (!bh)
return read?read:-EIO;
chars = (count<BLOCK_SIZE) ? count : BLOCK_SIZE;
p = offset + bh->b_data;
offset = 0;
block++;
*pos += chars;
read += chars;
count -= chars;
while (chars-->0)
put_fs_byte(*(p++),buf++);
bh->b_dirt = 1;
brelse(bh);
}
return read;
}
extern void rw_hd(int rw, struct buffer_head * bh);
typedef void (*blk_fn)(int rw, struct buffer_head * bh);
static blk_fn rd_blk[]={
NULL, /* nodev */
NULL, /* dev mem */
NULL, /* dev fd */
rw_hd, /* dev hd */
NULL, /* dev ttyx */
NULL, /* dev tty */
NULL}; /* dev lp */
void ll_rw_block(int rw, struct buffer_head * bh)
{
blk_fn blk_addr;
unsigned int major;
if ((major=MAJOR(bh->b_dev)) >= NR_BLK_DEV || !(blk_addr=rd_blk[major]))
panic("Trying to read nonexistent block-device");
blk_addr(rw, bh);
}