/* *  linux/fs/block_dev.c * *  (C) 1991  Linus Torvalds */#include <errno.h>#include <linux/sched.h>#include <linux/kernel.h>#include <asm/segment.h>#include <asm/system.h>int block_write(int dev, long * pos, char * buf, int count){	int block = *pos >> BLOCK_SIZE_BITS;	int offset = *pos & (BLOCK_SIZE-1);	int chars;	int written = 0;	struct buffer_head * bh;	register char * p;	while (count>0) {		chars = BLOCK_SIZE - offset;		if (chars > count)			chars=count;		if (chars == BLOCK_SIZE)			bh = getblk(dev,block);		else			bh = breada(dev,block,block+1,block+2,-1);		block++;		if (!bh)			return written?written:-EIO;		p = offset + bh->b_data;		offset = 0;		*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_BITS;	int offset = *pos & (BLOCK_SIZE-1);	int chars;	int read = 0;	struct buffer_head * bh;	register char * p;	while (count>0) {		chars = BLOCK_SIZE-offset;		if (chars > count)			chars = count;		if (!(bh = breada(dev,block,block+1,block+2,-1)))			return read?read:-EIO;		block++;		p = offset + bh->b_data;		offset = 0;		*pos += chars;		read += chars;		count -= chars;		while (chars-->0)			put_fs_byte(*(p++),buf++);		brelse(bh);	}	return read;}