cfs.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>

#include "cformat.h"
#include "lru.h"
#include "bcache.h"
#include "disk.h"
#include "inode.h"
#include "file.h"
#include "stats.h"

enum
{
	Nfid=		10240,
};

/* maximum length of a file */
#define MAXLEN 0x7fffffffffffffffLL

typedef struct Mfile Mfile;
typedef struct Ram Ram;
typedef struct P9fs P9fs;

struct Mfile
{
	Qid	qid;
	char	busy;
};

Mfile	mfile[Nfid];
Icache	ic;
int	debug, statson;

struct P9fs
{
	int	fd[2];
	Fcall	rhdr;
	Fcall	thdr;
	long	len;
	char	*name;
};

P9fs	c;	/* client conversation */
P9fs	s;	/* server conversation */

struct Cfsstat  cfsstat, cfsprev;
char	statbuf[2048];
int	statlen;

#define	MAXFDATA	8192	/* i/o size for read/write */

int		messagesize = MAXFDATA+IOHDRSZ;

uchar	datasnd[MAXFDATA + IOHDRSZ];
uchar	datarcv[MAXFDATA + IOHDRSZ];

Qid	rootqid;
Qid	ctlqid = {0x5555555555555555LL, 0, 0};

void	rversion(void);
void	rauth(Mfile*);
void	rflush(void);
void	rattach(Mfile*);
void	rwalk(Mfile*);
void	ropen(Mfile*);
void	rcreate(Mfile*);
void	rread(Mfile*);
void	rwrite(Mfile*);
void	rclunk(Mfile*);
void	rremove(Mfile*);
void	rstat(Mfile*);
void	rwstat(Mfile*);
void	error(char*, ...);
void	warning(char*);
void	mountinit(char*, char*);
void	io(void);
void	sendreply(char*);
void	sendmsg(P9fs*, Fcall*);
void	rcvmsg(P9fs*, Fcall*);
int	delegate(void);
int	askserver(void);
void	cachesetup(int, char*);
int	ctltest(Mfile*);
void	genstats(void);

char *mname[]={
	[Tversion]		"Tversion",
	[Tauth]	"Tauth",
	[Tflush]	"Tflush",
	[Tattach]	"Tattach",
	[Twalk]		"Twalk",
	[Topen]		"Topen",
	[Tcreate]	"Tcreate",
	[Tclunk]	"Tclunk",
	[Tread]		"Tread",
	[Twrite]	"Twrite",
	[Tremove]	"Tremove",
	[Tstat]		"Tstat",
	[Twstat]	"Twstat",
	[Rversion]	"Rversion",
	[Rauth]	"Rauth",
	[Rerror]	"Rerror",
	[Rflush]	"Rflush",
	[Rattach]	"Rattach",
	[Rwalk]		"Rwalk",
	[Ropen]		"Ropen",
	[Rcreate]	"Rcreate",
	[Rclunk]	"Rclunk",
	[Rread]		"Rread",
	[Rwrite]	"Rwrite",
	[Rremove]	"Rremove",
	[Rstat]		"Rstat",
	[Rwstat]	"Rwstat",
			0,
};

void
usage(void)
{
	fprint(2, "usage:\tcfs -s [-rd] [-f partition]");
	fprint(2, "\tcfs [-rd] [-f partition] [-a netaddr] [mt-pt]\n");
	exits("usage");
}

void
main(int argc, char *argv[])
{
	int std;
	int format;
	char *part;
	char *server;
	char *mtpt;

	std = 0;
	format = 0;
	part = "/dev/sdC0/cache";
	server = "il!emelie";
	mtpt = "/tmp";

	ARGBEGIN{
	case 'a':
		server = ARGF();
		if(server == 0)
			usage();
		break;
	case 'S':
		statson = 1;
		break;
	case 's':
		std = 1;
		break;
	case 'r':
		format = 1;
		break;
	case 'f':
		part = ARGF();
		if(part == 0)
			usage();
		break;
	case 'd':
		debug = 1;
		break;
	default:
		usage();
	}ARGEND
	if(argc && *argv)
		mtpt = *argv;

	if(debug)
		fmtinstall('F', fcallfmt);

	cachesetup(format, part);

	c.name = "client";
	s.name = "server";
	if(std){
		c.fd[0] = c.fd[1] = 1;
		s.fd[0] = s.fd[1] = 0;
	}else
		mountinit(server, mtpt);

	switch(fork()){
	case 0:
		io();
		exits("");
	case -1:
		error("fork");
	default:
		exits("");
	}
}

void
cachesetup(int format, char *partition)
{
	int f;
	int secsize;
	int inodes;
	int blocksize;

	secsize = 512;
	inodes = 1024;
	blocksize = 4*1024;

	f = open(partition, ORDWR);
	if(f < 0)
		error("opening partition");

	if(format || iinit(&ic, f, secsize)<0){
		if(iformat(&ic, f, inodes, "bootes", blocksize, secsize) < 0)
			error("formatting failed");
	}
}

void
mountinit(char *server, char *mountpoint)
{
	int p[2];

	/*
	 *  grab a channel and call up the file server
	 */
	s.fd[0] = s.fd[1] = dial(netmkaddr(server, 0, "9fs"), 0, 0, 0);
	if(s.fd[0] < 0)
		error("opening data");

	/*
 	 *  mount onto name space
	 */
	if(pipe(p) < 0)
		error("pipe failed");
	switch(fork()){
	case 0:
		break;
	default:
		if(amount(p[1], mountpoint, MREPL|MCREATE, "") < 0)
			error("mount failed");
		exits(0);
	case -1:
		error("fork failed\n");
/*BUG: no wait!*/
	}
	c.fd[0] = c.fd[1] = p[0];
}

void
io(void)
{
	int type;
	Mfile *mf;
    loop:
	rcvmsg(&c, &c.thdr);

	type = c.thdr.type;

	if(statson){
		cfsstat.cm[type].n++;
		cfsstat.cm[type].s = nsec();
	}
	mf = &mfile[c.thdr.fid];
	switch(type){
	default:
		error("type");
		break;
	case Tversion:
		rversion();
		break;
	case Tauth:
		mf = &mfile[c.thdr.afid];
		rauth(mf);
		break;
	case Tflush:
		rflush();
		break;
	case Tattach:
		rattach(mf);
		break;
	case Twalk:
		rwalk(mf);
		break;
	case Topen:
		ropen(mf);
		break;
	case Tcreate:
		rcreate(mf);
		break;
	case Tread:
		rread(mf);
		break;
	case Twrite:
		rwrite(mf);
		break;
	case Tclunk:
		rclunk(mf);
		break;
	case Tremove:
		rremove(mf);
		break;
	case Tstat:
		rstat(mf);
		break;
	case Twstat:
		rwstat(mf);
		break;
	}
	if(statson){
		cfsstat.cm[type].t += nsec() -cfsstat.cm[type].s;
	}
	goto loop;
}

void
rversion(void)
{
	if(messagesize > c.thdr.msize)
		messagesize = c.thdr.msize;
	c.thdr.msize = messagesize;	/* set downstream size */
	delegate();
}

void
rauth(Mfile *mf)
{
	if(mf->busy)
		error("auth to used channel");

	if(delegate() == 0){
		mf->qid = s.rhdr.aqid;
		mf->busy = 1;
	}
}

void
rflush(void)		/* synchronous so easy */
{
	sendreply(0);
}

void
rattach(Mfile *mf)
{
	if(delegate() == 0){
		mf->qid = s.rhdr.qid;
		mf->busy = 1;
		if (statson == 1){
			statson++;
			rootqid = mf->qid;
		}
	}
}

void
rwalk(Mfile *mf)
{
	Mfile *nmf;

	nmf = nil;
	if(statson
	  && mf->qid.type == rootqid.type && mf->qid.path == rootqid.path
	  && c.thdr.nwname == 1 && strcmp(c.thdr.wname[0], "cfsctl") == 0){
		/* This is the ctl file */
		nmf = &mfile[c.thdr.newfid];
		if(c.thdr.newfid != c.thdr.fid && nmf->busy)
			error("clone to used channel");
		nmf = &mfile[c.thdr.newfid];
		nmf->qid = ctlqid;
		nmf->busy = 1;
		c.rhdr.nwqid = 1;
		c.rhdr.wqid[0] = ctlqid;
		sendreply(0);
		return;
	}
	if(c.thdr.newfid != c.thdr.fid){
		if(c.thdr.newfid >= Nfid)
			error("clone nfid out of range");
		nmf = &mfile[c.thdr.newfid];
		if(nmf->busy)
			error("clone to used channel");
		nmf = &mfile[c.thdr.newfid];
		nmf->qid = mf->qid;
		nmf->busy = 1;
		mf = nmf; /* Walk mf */
	}

	if(delegate() < 0){	/* complete failure */
		if(nmf)
			nmf->busy = 0;
		return;
	}

	if(s.rhdr.nwqid == c.thdr.nwname){	/* complete success */
		if(s.rhdr.nwqid > 0)
			mf->qid = s.rhdr.wqid[s.rhdr.nwqid-1];
		return;
	}

	/* partial success; release fid */
	if(nmf)
		nmf->busy = 0;
}

void
ropen(Mfile *mf)
{
	if(statson && ctltest(mf)){
		/* Opening ctl file */
		if(c.thdr.mode != OREAD){
			sendreply("does not exist");
			return;
		}
		c.rhdr.qid = ctlqid;
		c.rhdr.iounit = 0;
		sendreply(0);
		genstats();
		return;
	}
	if(delegate() == 0){
		mf->qid = s.rhdr.qid;
		if(c.thdr.mode & OTRUNC)
			iget(&ic, mf->qid);
	}
}

void
rcreate(Mfile *mf)
{
	if(statson && ctltest(mf)){
		sendreply("exists");
		return;
	}
	if(delegate() == 0){
		mf->qid = s.rhdr.qid;
		mf->qid.vers++;
	}