NFS Lockd Kernel Patch Proposal

The following file includes patch to export set/reset capabilityes of the
grace period to user-level via the proc filesystem.
Traces of the need for this feature were included in the code but the code
was not actually included so this should not be
big news to the previous writers of the lockd code.

I will appreciate this to be considered for inclusion in the kernel
distribution. This feature is an enabler for HA-NFS.

(See attached file: svc.c)

Regards, Juan Gomez
/*
 * linux/fs/lockd/svc.c
 *
 * This is the central lockd service.
 *
 * FIXME: Separate the lockd NFS server functionality from the lockd NFS
 * 	  client functionality. Oh why didn't Sun create two separate
 *	  services in the first place?
 *
 * Authors:	Olaf Kirch (okir@monad.swb.de)
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#define __KERNEL_SYSCALLS__
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/uio.h>
#include <linux/version.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>

#include <linux/sunrpc/types.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/lockd/lockd.h>
#include <linux/nfs.h>

#define NLM_PROC_FS     /* Enable a proc filesystem to set NLM varibales */

#ifdef NLM_PROC_FS

#include <linux/proc_fs.h>

#endif                  /* #ifdef NLM_PROC_FS */

#define NLMDBG_FACILITY		NLMDBG_SVC
#define LOCKD_BUFSIZE		(1024 + NLMSSVC_XDRSIZE)
#define ALLOWED_SIGS		(sigmask(SIGKILL))

extern struct svc_program	nlmsvc_program;
struct nlmsvc_binding *		nlmsvc_ops;
static DECLARE_MUTEX(nlmsvc_sema);
static unsigned int		nlmsvc_users;
static pid_t			nlmsvc_pid;
int				nlmsvc_grace_period;
unsigned long			nlmsvc_timeout;

static DECLARE_MUTEX_LOCKED(lockd_start);
static DECLARE_WAIT_QUEUE_HEAD(lockd_exit);

/*
 * Currently the following can be set only at insmod time.
 * Ideally, they would be accessible through the sysctl interface.
 */
unsigned long			nlm_grace_period;
unsigned long			nlm_timeout = LOCKD_DFLT_TIMEO;
unsigned long			nlm_udpport, nlm_tcpport;

static unsigned long set_grace_period(void)
{
	unsigned long grace_period;

	/* Note: nlm_timeout should always be nonzero */
	if (nlm_grace_period)
		grace_period = ((nlm_grace_period + nlm_timeout - 1)
				/ nlm_timeout) * nlm_timeout * HZ;
	else
		grace_period = nlm_timeout * 5 * HZ;
	nlmsvc_grace_period = 1;
	return grace_period + jiffies;
}

static inline void clear_grace_period(void)
{
	nlmsvc_grace_period = 0;
}


#ifdef  NLM_PROC_FS

/*
 * This code enable user-level control of the grace period state of the lockd
 * daemon.
 */


/* 1: nlm_proc_fs not intialized, 0: initialized */
static int nlm_proc_fs_init_flag = 1;

static unsigned long grace_period_expire;




/* Function used to read grace period status of lockd */

static ssize_t
nlmsvc_grace_period_read(char *page, 
                         char **start, 
                         off_t off,
                         int count, 
                         int *eof, 
                         void *data)
{
    char        *s = nlmsvc_grace_period ? "1" : "0";
    int         len = strlen(s);

    *eof = 0;
    *start = page;

    if (off < 0)
        return -EINVAL;

    if (off >= len){
      *eof = 1;
      return 0;
    }

    if (len < (off + count)) {

      *eof = 1;
      count = len - off;

    } else {

      count = len;

    }

    memcpy(page, s + off, count);

    return count;

}/* static ssize_t nlmsvc_grace_period_read() */


/*
 * Set status of entry/binfmt_misc:
 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
 */
static int parse_command(const char *buffer, size_t count)
{
	char s[4];

	if (!count)
		return 0;

	if (count > 3)
		return -EINVAL;

	memcpy(s, buffer, count);

	if (s[count-1] == '\n')
		count--;

	if (count == 1 && s[0] == '0')
		return 1;

	if (count == 1 && s[0] == '1')
		return 2;

	return -EINVAL;

}

/* Function used to set/reset grace period status of lockd */

static ssize_t nlmsvc_grace_period_write(struct file *file, 
                                         const char *buffer,
                                         unsigned long count,
                                         void *data)
{
    int res = parse_command(buffer, count);
    struct dentry *root;
    
    switch (res) {
    case 1: 
        clear_grace_period();
        break;
    case 2: 
        grace_period_expire = set_grace_period();
        break;
    default: 
        return res;
    }
    return count;

}/* static ssize_t nlmsvc_grace_period_write() */





static struct proc_dir_entry *base;


static void nlm_proc_fs_init()
{
  struct proc_dir_entry *p;

  if (nlm_proc_fs_init_flag){
    
    if (!(base = proc_mkdir("nlm", proc_root_fs)))
      return;
    
    nlm_proc_fs_init_flag = 0;

    if ((p = create_proc_entry("nlmsvc_grace_period", 0, base))) {

      p->read_proc = nlmsvc_grace_period_read;
      p->write_proc = nlmsvc_grace_period_write;

    }
    
  }

}/* static int nlm_proc_fs_init() */




static void nlm_proc_fs_exit()
{

    if (!nlm_proc_fs_init_flag && base){
        
      remove_proc_entry("nlmsvc_grace_period", base);
      remove_proc_entry("nlm", proc_root_fs);

    }

}/* static void nlm_proc_fs_exit() */

#endif  /* #ifdef  NLM_PROC_FS */


/*
 * This is the lockd kernel thread
 */
static void
lockd(struct svc_rqst *rqstp)
{
	struct svc_serv	*serv = rqstp->rq_server;
	int		err = 0;
#ifndef NLM_PROC_FS
        unsigned long grace_period_expire;
#endif

	/* Lock module and set up kernel thread */
	MOD_INC_USE_COUNT;
	lock_kernel();

	/*
	 * Let our maker know we're running.
	 */
	nlmsvc_pid = current->pid;
	up(&lockd_start);

	daemonize();
	reparent_to_init();
	sprintf(current->comm, "lockd");

	/* Process request with signals blocked.  */
	spin_lock_irq(&current->sigmask_lock);
	siginitsetinv(&current->blocked, sigmask(SIGKILL));
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);

	/* kick rpciod */
	rpciod_up();

	dprintk("NFS locking service started (ver " LOCKD_VERSION ").\n");

	if (!nlm_timeout)
		nlm_timeout = LOCKD_DFLT_TIMEO;
	nlmsvc_timeout = nlm_timeout * HZ;

	grace_period_expire = set_grace_period();

	/*
	 * The main request loop. We don't terminate until the last
	 * NFS mount or NFS daemon has gone away, and we've been sent a
	 * signal, or else another process has taken over our job.
	 */
	while ((nlmsvc_users || !signalled()) && nlmsvc_pid == current->pid)
	{
		long timeout = MAX_SCHEDULE_TIMEOUT;
		if (signalled()) {
			spin_lock_irq(&current->sigmask_lock);
			flush_signals(current);
			spin_unlock_irq(&current->sigmask_lock);
			if (nlmsvc_ops) {
				nlmsvc_ops->detach();
				grace_period_expire = set_grace_period();
			}
		}

		/*
		 * Retry any blocked locks that have been notified by
		 * the VFS. Don't do this during grace period.
		 * (Theoretically, there shouldn't even be blocked locks
		 * during grace period).
		 */
		if (!nlmsvc_grace_period) {
			timeout = nlmsvc_retry_blocked();
		} else if (time_before(grace_period_expire, jiffies))
			clear_grace_period();

		/*
		 * Find a socket with data available and call its
		 * recvfrom routine.
		 */
		err = svc_recv(serv, rqstp, timeout);
		if (err == -EAGAIN || err == -EINTR)
			continue;
		if (err < 0) {
			printk(KERN_WARNING
			       "lockd: terminating on error %d\n",
			       -err);
			break;
		}

		dprintk("lockd: request from %08x\n",
			(unsigned)ntohl(rqstp->rq_addr.sin_addr.s_addr));

		/*
		 * Look up the NFS client handle. The handle is needed for
		 * all but the GRANTED callback RPCs.
		 */
		rqstp->rq_client = NULL;
		if (nlmsvc_ops) {
			nlmsvc_ops->exp_readlock();
			rqstp->rq_client =
				nlmsvc_ops->exp_getclient(&rqstp->rq_addr);
		}

		svc_process(serv, rqstp);

		/* Unlock export hash tables */
		if (nlmsvc_ops)
			nlmsvc_ops->exp_unlock();
	}

	/*
	 * Check whether there's a new lockd process before
	 * shutting down the hosts and clearing the slot.
	 */
	if (!nlmsvc_pid || current->pid == nlmsvc_pid) {
		if (nlmsvc_ops)
			nlmsvc_ops->detach();
		nlm_shutdown_hosts();
		nlmsvc_pid = 0;
	} else
		printk(KERN_DEBUG
			"lockd: new process, skipping host shutdown\n");
	wake_up(&lockd_exit);
		
	/* Exit the RPC thread */
	svc_exit_thread(rqstp);

	/* release rpciod */
	rpciod_down();

	/* Release module */
	MOD_DEC_USE_COUNT;
}


/*
 * Bring up the lockd process if it's not already up.
 */
int
lockd_up(void)
{
	static int		warned = 0; 
	struct svc_serv *	serv;
	int			error = 0;

	down(&nlmsvc_sema);


	/*
	 * Unconditionally increment the user count ... this is
	 * the number of clients who _want_ a lockd process.
	 */
	nlmsvc_users++; 
	/*
	 * Check whether we're already up and running.
	 */
	if (nlmsvc_pid)
		goto out;

#ifdef NLM_PROC_FS      
        nlm_proc_fs_init();
#endif
	/*
	 * Sanity check: if there's no pid,
	 * we should be the first user ...
	 */
	if (nlmsvc_users > 1)
		printk(KERN_WARNING
			"lockd_up: no pid, %d users??\n", nlmsvc_users);

	error = -ENOMEM;
	serv = svc_create(&nlmsvc_program, 0, NLMSVC_XDRSIZE);
	if (!serv) {
		printk(KERN_WARNING "lockd_up: create service failed\n");
		goto out;
	}

	if ((error = svc_makesock(serv, IPPROTO_UDP, nlm_udpport)) < 0 
#ifdef CONFIG_NFSD_TCP
	 || (error = svc_makesock(serv, IPPROTO_TCP, nlm_tcpport)) < 0
#endif
		) {
		if (warned++ == 0) 
			printk(KERN_WARNING
				"lockd_up: makesock failed, error=%d\n", error);
		goto destroy_and_out;
	} 
	warned = 0;

	/*
	 * Create the kernel thread and wait for it to start.
	 */
	error = svc_create_thread(lockd, serv);
	if (error) {
		printk(KERN_WARNING
			"lockd_up: create thread failed, error=%d\n", error);
		goto destroy_and_out;
	}
	down(&lockd_start);

	/*
	 * Note: svc_serv structures have an initial use count of 1,
	 * so we exit through here on both success and failure.
	 */
destroy_and_out:
	svc_destroy(serv);
out:
	up(&nlmsvc_sema);
	return error;
}

/*
 * Decrement the user count and bring down lockd if we're the last.
 */
void
lockd_down(void)
{
	static int warned = 0; 

	down(&nlmsvc_sema);

	if (nlmsvc_users) {
		if (--nlmsvc_users)
			goto out;
	} else
		printk(KERN_WARNING "lockd_down: no users! pid=%d\n", nlmsvc_pid);

#ifdef NLM_PROC_FS      
        nlm_proc_fs_exit();
#endif

	if (!nlmsvc_pid) {
		if (warned++ == 0)
			printk(KERN_WARNING "lockd_down: no lockd running.\n"); 
		goto out;
	}
	warned = 0;

	kill_proc(nlmsvc_pid, SIGKILL, 1);
	/*
	 * Wait for the lockd process to exit, but since we're holding
	 * the lockd semaphore, we can't wait around forever ...
	 */
	current->sigpending = 0;
	interruptible_sleep_on_timeout(&lockd_exit, HZ);
	if (nlmsvc_pid) {
		printk(KERN_WARNING 
			"lockd_down: lockd failed to exit, clearing pid\n");
		nlmsvc_pid = 0;
	}
	spin_lock_irq(&current->sigmask_lock);
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);
out:
	up(&nlmsvc_sema);
}

#ifdef MODULE
/* New module support in 2.1.18 */

MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
MODULE_DESCRIPTION("NFS file locking service version " LOCKD_VERSION ".");
MODULE_LICENSE("GPL");
MODULE_PARM(nlm_grace_period, "10-240l");
MODULE_PARM(nlm_timeout, "3-20l");
MODULE_PARM(nlm_udpport, "0-65535l");
MODULE_PARM(nlm_tcpport, "0-65535l");

int
init_module(void)
{
	/* Init the static variables */
	init_MUTEX(&nlmsvc_sema);
	nlmsvc_users = 0;
	nlmsvc_pid = 0;
	return 0;
}

void
cleanup_module(void)
{
	/* FIXME: delete all NLM clients */
	nlm_shutdown_hosts();
}
#else
/* not a module, so process bootargs
 * lockd.udpport and lockd.tcpport
 */

static int __init udpport_set(char *str)
{
	nlm_udpport = simple_strtoul(str, NULL, 0);
	return 1;
}
static int __init tcpport_set(char *str)
{
	nlm_tcpport = simple_strtoul(str, NULL, 0);
	return 1;
}
__setup("lockd.udpport=", udpport_set);
__setup("lockd.tcpport=", tcpport_set);

#endif

/*
 * Define NLM program and procedures
 */
static struct svc_version	nlmsvc_version1 = {
	1, 17, nlmsvc_procedures, NULL
};
static struct svc_version	nlmsvc_version3 = {
	3, 24, nlmsvc_procedures, NULL
};
#ifdef CONFIG_LOCKD_V4
static struct svc_version	nlmsvc_version4 = {
	4, 24, nlmsvc_procedures4, NULL
};
#endif
static struct svc_version *	nlmsvc_version[] = {
	NULL,
	&nlmsvc_version1,
	NULL,
	&nlmsvc_version3,
#ifdef CONFIG_LOCKD_V4
	&nlmsvc_version4,
#endif
};

static struct svc_stat		nlmsvc_stats;

#define NLM_NRVERS	(sizeof(nlmsvc_version)/sizeof(nlmsvc_version[0]))
struct svc_program		nlmsvc_program = {
	NLM_PROGRAM,		/* program number */
	1, NLM_NRVERS-1,	/* version range */
	NLM_NRVERS,		/* number of entries in nlmsvc_version */
	nlmsvc_version,		/* version table */
	"lockd",		/* service name */
	&nlmsvc_stats,		/* stats table */
};