statfs.h

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

/*
 * statfs.h - definitions for statistic gathering file server
 */

#define DEBUGFILE	"iostats.out"
#define DONESTR		"done"
#define DEBUG		if(!dbg){}else fprint
#define MAXPROC		16
#define FHASHSIZE	64
#define fidhash(s)	fhash[s%FHASHSIZE]

enum{
	Maxfdata	= 8192,	/* max size of data in 9P message */
	Maxrpc		= 20000,/* number of RPCs we'll log */
};

typedef struct Fsrpc Fsrpc;
typedef struct Fid Fid;
typedef struct File File;
typedef struct Proc Proc;
typedef struct Stats Stats;
typedef struct Rpc Rpc;
typedef struct Frec Frec;

struct Frec
{
	Frec	*next;
	char	*op;
	ulong	nread;
	ulong	nwrite;
	ulong	bread;
	ulong	bwrite;
	ulong	opens;
};

struct Rpc
{
	char	*name;
	ulong	count;
	vlong	time;
	vlong	lo;
	vlong	hi;
	ulong	bin;
	ulong	bout;
};

struct Stats
{
	ulong	totread;
	ulong	totwrite;
	ulong	nrpc;
	ulong	nproto;
	Rpc	rpc[Maxrpc];
};

struct Fsrpc
{
	int	busy;			/* Work buffer has pending rpc to service */
	uintptr	pid;			/* Pid of slave process executing the rpc */
	int	canint;			/* Interrupt gate */
	int	flushtag;		/* Tag on which to reply to flush */
	Fcall	work;			/* Plan 9 incoming Fcall */
	uchar	buf[IOHDRSZ+Maxfdata];	/* Data buffer */
};

struct Fid
{
	int	fid;			/* system fd for i/o */
	File	*f;			/* File attached to this fid */
	int	mode;
	int	nr;			/* fid number */
	Fid	*next;			/* hash link */
	ulong	nread;
	ulong	nwrite;
	ulong	bread;
	ulong	bwrite;
	vlong	offset;			/* for directories */
};

struct File
{
	char	*name;
	Qid	qid;
	int	inval;
	File	*parent;
	File	*child;
	File	*childlist;
};

struct Proc
{
	uintptr	pid;
	int	busy;
	Proc	*next;
};

enum
{
	Nr_workbufs 	= 40,
	Dsegpad		= 8192,
	Fidchunk	= 1000,
};

Extern Fsrpc	*Workq;
Extern int  	dbg;
Extern File	*root;
Extern Fid	**fhash;
Extern Fid	*fidfree;
Extern int	qid;
Extern Proc	*Proclist;
Extern int	done;
Extern Stats	*stats;
Extern Frec	*frhead;
Extern Frec	*frtail;
Extern int	myiounit;

/* File system protocol service procedures */
void Xcreate(Fsrpc*), Xclunk(Fsrpc*); 
void Xversion(Fsrpc*), Xauth(Fsrpc*), Xflush(Fsrpc*); 
void Xattach(Fsrpc*), Xwalk(Fsrpc*), Xauth(Fsrpc*);
void Xremove(Fsrpc*), Xstat(Fsrpc*), Xwstat(Fsrpc*);
void slave(Fsrpc*);

void	reply(Fcall*, Fcall*, char*);
Fid 	*getfid(int);
int	freefid(int);
Fid	*newfid(int);
Fsrpc	*getsbuf(void);
void	initroot(void);
void	fatal(char*);
void	makepath(char*, File*, char*);
File	*file(File*, char*);
void	slaveopen(Fsrpc*);
void	slaveread(Fsrpc*);
void	slavewrite(Fsrpc*);
void	blockingslave(void);
void	reopen(Fid *f);
void	noteproc(int, char*);
void	flushaction(void*, char*);
void	catcher(void*, char*);
ulong	msec(void);
void	fidreport(Fid*);