clntproc.c

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	struct nlm_host	*host = req->a_host;
	struct rpc_clnt	*clnt;
	struct nlm_args	*argp = &req->a_args;
	struct nlm_res	*resp = &req->a_res;
	struct file	*file = argp->lock.fl.fl_file;
	struct rpc_message msg;
	int		status;

	dprintk("lockd: call procedure %s on %s (async)\n",
			nlm_procname(proc), host->h_name);

	/* If we have no RPC client yet, create one. */
	if ((clnt = nlm_bind_host(host)) == NULL)
		return -ENOLCK;

        /* bootstrap and kick off the async RPC call */
	msg.rpc_proc = proc;
	msg.rpc_argp = argp;
	msg.rpc_resp =resp;
	if (file)
		msg.rpc_cred = nfs_file_cred(file);
	else
		msg.rpc_cred = NULL;
	/* Increment host refcount */
	nlm_get_host(host);
        status = rpc_call_async(clnt, &msg, RPC_TASK_ASYNC, callback, req);
	if (status < 0)
		nlm_release_host(host);
	return status;
}

/*
 * TEST for the presence of a conflicting lock
 */
static int
nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
{
	int	status;

	if ((status = nlmclnt_call(req, NLMPROC_TEST)) < 0)
		return status;

	status = req->a_res.status;
	if (status == NLM_LCK_GRANTED) {
		fl->fl_type = F_UNLCK;
	} if (status == NLM_LCK_DENIED) {
		/*
		 * Report the conflicting lock back to the application.
		 * FIXME: Is it OK to report the pid back as well?
		 */
		locks_copy_lock(fl, &req->a_res.lock.fl);
		/* fl->fl_pid = 0; */
	} else {
		return nlm_stat_to_errno(req->a_res.status);
	}

	return 0;
}

static
void nlmclnt_insert_lock_callback(struct file_lock *fl)
{
	nlm_get_host(fl->fl_u.nfs_fl.host);
}
static
void nlmclnt_remove_lock_callback(struct file_lock *fl)
{
	if (fl->fl_u.nfs_fl.host) {
		nlm_release_host(fl->fl_u.nfs_fl.host);
		fl->fl_u.nfs_fl.host = NULL;
	}
}

/*
 * LOCK: Try to create a lock
 *
 *			Programmer Harassment Alert
 *
 * When given a blocking lock request in a sync RPC call, the HPUX lockd
 * will faithfully return LCK_BLOCKED but never cares to notify us when
 * the lock could be granted. This way, our local process could hang
 * around forever waiting for the callback.
 *
 *  Solution A:	Implement busy-waiting
 *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 *
 * For now I am implementing solution A, because I hate the idea of
 * re-implementing lockd for a third time in two months. The async
 * calls shouldn't be too hard to do, however.
 *
 * This is one of the lovely things about standards in the NFS area:
 * they're so soft and squishy you can't really blame HP for doing this.
 */
static int
nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
{
	struct nlm_host	*host = req->a_host;
	struct nlm_res	*resp = &req->a_res;
	int		status;

	if (!host->h_monitored && nsm_monitor(host) < 0) {
		printk(KERN_NOTICE "lockd: failed to monitor %s\n",
					host->h_name);
		return -ENOLCK;
	}

	do {
		if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0) {
			if (resp->status != NLM_LCK_BLOCKED)
				break;
			status = nlmclnt_block(host, fl, &resp->status);
		}
		if (status < 0)
			return status;
	} while (resp->status == NLM_LCK_BLOCKED);

	if (resp->status == NLM_LCK_GRANTED) {
		fl->fl_u.nfs_fl.state = host->h_state;
		fl->fl_u.nfs_fl.flags |= NFS_LCK_GRANTED;
		fl->fl_u.nfs_fl.host = host;
		fl->fl_insert = nlmclnt_insert_lock_callback;
		fl->fl_remove = nlmclnt_remove_lock_callback;
	}

	return nlm_stat_to_errno(resp->status);
}

/*
 * RECLAIM: Try to reclaim a lock
 */
int
nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
{
	struct nlm_rqst reqst, *req;
	int		status;

	req = &reqst;
	memset(req, 0, sizeof(*req));
	locks_init_lock(&req->a_args.lock.fl);
	locks_init_lock(&req->a_res.lock.fl);
	req->a_host  = host;
	req->a_flags = 0;

	/* Set up the argument struct */
	nlmclnt_setlockargs(req, fl);
	req->a_args.reclaim = 1;

	if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0
	 && req->a_res.status == NLM_LCK_GRANTED)
		return 0;

	printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
				"(errno %d, status %d)\n", fl->fl_pid,
				status, req->a_res.status);

	/*
	 * FIXME: This is a serious failure. We can
	 *
	 *  a.	Ignore the problem
	 *  b.	Send the owning process some signal (Linux doesn't have
	 *	SIGLOST, though...)
	 *  c.	Retry the operation
	 *
	 * Until someone comes up with a simple implementation
	 * for b or c, I'll choose option a.
	 */

	return -ENOLCK;
}

/*
 * UNLOCK: remove an existing lock
 */
static int
nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
{
	struct nlm_res	*resp = &req->a_res;
	int		status;

	/* Clean the GRANTED flag now so the lock doesn't get
	 * reclaimed while we're stuck in the unlock call. */
	fl->fl_u.nfs_fl.flags &= ~NFS_LCK_GRANTED;

	if (req->a_flags & RPC_TASK_ASYNC) {
		return nlmclnt_async_call(req, NLMPROC_UNLOCK,
					nlmclnt_unlock_callback);
	}

	if ((status = nlmclnt_call(req, NLMPROC_UNLOCK)) < 0)
		return status;

	if (resp->status == NLM_LCK_GRANTED)
		return 0;

	if (resp->status != NLM_LCK_DENIED_NOLOCKS)
		printk("lockd: unexpected unlock status: %d\n", resp->status);

	/* What to do now? I'm out of my depth... */

	return -ENOLCK;
}

static void
nlmclnt_unlock_callback(struct rpc_task *task)
{
	struct nlm_rqst	*req = (struct nlm_rqst *) task->tk_calldata;
	int		status = req->a_res.status;

	if (RPC_ASSASSINATED(task))
		goto die;

	if (task->tk_status < 0) {
		dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
		goto retry_rebind;
	}
	if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
		rpc_delay(task, NLMCLNT_GRACE_WAIT);
		goto retry_unlock;
	}
	if (status != NLM_LCK_GRANTED)
		printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);

die:
	nlm_release_host(req->a_host);
	kfree(req);
	return;
 retry_rebind:
	nlm_rebind_host(req->a_host);
 retry_unlock:
	rpc_restart_call(task);
}

/*
 * Cancel a blocked lock request.
 * We always use an async RPC call for this in order not to hang a
 * process that has been Ctrl-C'ed.
 */
int
nlmclnt_cancel(struct nlm_host *host, struct file_lock *fl)
{
	struct nlm_rqst	*req;
	unsigned long	flags;
	sigset_t	oldset;
	int		status;

	/* Block all signals while setting up call */
	spin_lock_irqsave(&current->sigmask_lock, flags);
	oldset = current->blocked;
	sigfillset(&current->blocked);
	recalc_sigpending(current);
	spin_unlock_irqrestore(&current->sigmask_lock, flags);

	req = nlmclnt_alloc_call();
	if (!req)
		return -ENOMEM;
	req->a_host  = host;
	req->a_flags = RPC_TASK_ASYNC;

	nlmclnt_setlockargs(req, fl);

	status = nlmclnt_async_call(req, NLMPROC_CANCEL,
					nlmclnt_cancel_callback);
	if (status < 0)
		kfree(req);

	spin_lock_irqsave(&current->sigmask_lock, flags);
	current->blocked = oldset;
	recalc_sigpending(current);
	spin_unlock_irqrestore(&current->sigmask_lock, flags);

	return status;
}

static void
nlmclnt_cancel_callback(struct rpc_task *task)
{
	struct nlm_rqst	*req = (struct nlm_rqst *) task->tk_calldata;

	if (RPC_ASSASSINATED(task))
		goto die;

	if (task->tk_status < 0) {
		dprintk("lockd: CANCEL call error %d, retrying.\n",
					task->tk_status);
		goto retry_cancel;
	}

	dprintk("lockd: cancel status %d (task %d)\n",
			req->a_res.status, task->tk_pid);

	switch (req->a_res.status) {
	case NLM_LCK_GRANTED:
	case NLM_LCK_DENIED_GRACE_PERIOD:
		/* Everything's good */
		break;
	case NLM_LCK_DENIED_NOLOCKS:
		dprintk("lockd: CANCEL failed (server has no locks)\n");
		goto retry_cancel;
	default:
		printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
			req->a_res.status);
	}

die:
	nlm_release_host(req->a_host);
	kfree(req);
	return;

retry_cancel:
	nlm_rebind_host(req->a_host);
	rpc_restart_call(task);
	rpc_delay(task, 30 * HZ);
}

/*
 * Convert an NLM status code to a generic kernel errno
 */
static int
nlm_stat_to_errno(u32 status)
{
	switch(status) {
	case NLM_LCK_GRANTED:
		return 0;
	case NLM_LCK_DENIED:
		return -EAGAIN;
	case NLM_LCK_DENIED_NOLOCKS:
	case NLM_LCK_DENIED_GRACE_PERIOD:
		return -ENOLCK;
	case NLM_LCK_BLOCKED:
		printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
		return -ENOLCK;
#ifdef CONFIG_LOCKD_V4
	case NLM_DEADLCK:
		return -EDEADLK;
	case NLM_ROFS:
		return -EROFS;
	case NLM_STALE_FH:
		return -ESTALE;
	case NLM_FBIG:
		return -EOVERFLOW;
	case NLM_FAILED:
		return -ENOLCK;
#endif
	}
	printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
	return -ENOLCK;
}