#include <u.h>#include <libc.h>#include <blockalloc.h> u64intoffset2block(Disk *d, u64int offset){	return offset/(d->meta->blocksize);} u64intdread(Disk* d ,void *buf, u64int len, u64int offset){	Blockptr *block;	void *bbuf;	u64int ll = len;	u64int start = offset2block(d,offset);	u64int tblocks = len/(d->meta->blocksize);	u64int block0offset = offset - (start*d->meta->blocksize); 	buf = mallocz(len,0); // for performance reasons	if(len%(d->meta->blocksize) != 0)		tblocks++;	if(tblocks == 1){		readbptr(d,block,start);		readblock(d,block,bbuf);		memcpy(buf,(void*)((uchar*)bbuf+block0offset),(ulong)len);		free(bbuf);		return len;	}	for(u64int i = 0; i < tblocks; i++){		readbptr(d,block,start+i);		readblock(d,block,bbuf);		if(i == 0){			memcpy(buf,(void*)((uchar*)bbuf+block0offset),(ulong)(d->meta->blocksize-block0offset));			len = len - (d->meta->blocksize-block0offset);		} else {			if(len >= d->meta->blocksize){				memcpy((void*)((uchar*)buf+d->meta->blocksize*i),bbuf,d->meta->blocksize);			} else {				memcpy((void*)((uchar*)buf+d->meta->blocksize*i),bbuf,len);			}		}		free(bbuf);	}	return ll;} u64intdwrite(Disk* d , void *buf, u64int len, u64int offset){	Blockptr *block;	void *bbuf;	u64int ll = len;	u64int start = offset2block(d,offset);	u64int tblocks = len/(d->meta->blocksize);	u64int block0offset = offset - (start*d->meta->blocksize); 	if(len%(d->meta->blocksize) != 0)		tblocks++;	if(tblocks == 1){		readbptr(d,block,start);		readblock(d,block,bbuf);		memcpy((void*)((uchar*)bbuf+block0offset),buf,(ulong)len);		free(bbuf);		return len;	}	for(u64int i = 0; i < tblocks; i++){	start:		readbptr(d,block,start+i);		readblock(d,block,bbuf);		if(i == 0){			memcpy((void*)((uchar*)bbuf+block0offset),buf,(ulong)(d->meta->blocksize-block0offset));			len = len - (d->meta->blocksize-block0offset);		} else {			if(len >= d->meta->blocksize)				memcpy(bbuf,(void*)((uchar*)buf+d->meta->blocksize*i),d->meta->blocksize);			else				memcpy(bbuf,(void*)((uchar*)buf+d->meta->blocksize*i),len);		}		if(writeblock(d,block,bbuf) < d->meta->blocksize){			len = ll;			goto start;		}		free(bbuf);	}	return ll;}