clntproc.c 20.6 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
/*
 * linux/fs/lockd/clntproc.c
 *
 * RPC procedures for the client side NLM implementation
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/nfs_fs.h>
#include <linux/utsname.h>
#include <linux/smp_lock.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/sm_inter.h>

#define NLMDBG_FACILITY		NLMDBG_CLIENT
#define NLMCLNT_GRACE_WAIT	(5*HZ)
24
#define NLMCLNT_POLL_TIMEOUT	(30*HZ)
L
Linus Torvalds 已提交
25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556

static int	nlmclnt_test(struct nlm_rqst *, struct file_lock *);
static int	nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
static int	nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
static void	nlmclnt_unlock_callback(struct rpc_task *);
static void	nlmclnt_cancel_callback(struct rpc_task *);
static int	nlm_stat_to_errno(u32 stat);
static void	nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);

/*
 * Cookie counter for NLM requests
 */
static u32	nlm_cookie = 0x1234;

static inline void nlmclnt_next_cookie(struct nlm_cookie *c)
{
	memcpy(c->data, &nlm_cookie, 4);
	memset(c->data+4, 0, 4);
	c->len=4;
	nlm_cookie++;
}

static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
{
	atomic_inc(&lockowner->count);
	return lockowner;
}

static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
{
	if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
		return;
	list_del(&lockowner->list);
	spin_unlock(&lockowner->host->h_lock);
	nlm_release_host(lockowner->host);
	kfree(lockowner);
}

static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
{
	struct nlm_lockowner *lockowner;
	list_for_each_entry(lockowner, &host->h_lockowners, list) {
		if (lockowner->pid == pid)
			return -EBUSY;
	}
	return 0;
}

static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
{
	uint32_t res;
	do {
		res = host->h_pidcount++;
	} while (nlm_pidbusy(host, res) < 0);
	return res;
}

static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
{
	struct nlm_lockowner *lockowner;
	list_for_each_entry(lockowner, &host->h_lockowners, list) {
		if (lockowner->owner != owner)
			continue;
		return nlm_get_lockowner(lockowner);
	}
	return NULL;
}

static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
{
	struct nlm_lockowner *res, *new = NULL;

	spin_lock(&host->h_lock);
	res = __nlm_find_lockowner(host, owner);
	if (res == NULL) {
		spin_unlock(&host->h_lock);
		new = (struct nlm_lockowner *)kmalloc(sizeof(*new), GFP_KERNEL);
		spin_lock(&host->h_lock);
		res = __nlm_find_lockowner(host, owner);
		if (res == NULL && new != NULL) {
			res = new;
			atomic_set(&new->count, 1);
			new->owner = owner;
			new->pid = __nlm_alloc_pid(host);
			new->host = nlm_get_host(host);
			list_add(&new->list, &host->h_lockowners);
			new = NULL;
		}
	}
	spin_unlock(&host->h_lock);
	if (new != NULL)
		kfree(new);
	return res;
}

/*
 * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 */
static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
{
	struct nlm_args	*argp = &req->a_args;
	struct nlm_lock	*lock = &argp->lock;

	nlmclnt_next_cookie(&argp->cookie);
	argp->state   = nsm_local_state;
	memcpy(&lock->fh, NFS_FH(fl->fl_file->f_dentry->d_inode), sizeof(struct nfs_fh));
	lock->caller  = system_utsname.nodename;
	lock->oh.data = req->a_owner;
	lock->oh.len  = sprintf(req->a_owner, "%d@%s",
				current->pid, system_utsname.nodename);
	locks_copy_lock(&lock->fl, fl);
}

static void nlmclnt_release_lockargs(struct nlm_rqst *req)
{
	struct file_lock *fl = &req->a_args.lock.fl;

	if (fl->fl_ops && fl->fl_ops->fl_release_private)
		fl->fl_ops->fl_release_private(fl);
}

/*
 * Initialize arguments for GRANTED call. The nlm_rqst structure
 * has been cleared already.
 */
int
nlmclnt_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
{
	locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
	memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
	call->a_args.lock.caller = system_utsname.nodename;
	call->a_args.lock.oh.len = lock->oh.len;

	/* set default data area */
	call->a_args.lock.oh.data = call->a_owner;

	if (lock->oh.len > NLMCLNT_OHSIZE) {
		void *data = kmalloc(lock->oh.len, GFP_KERNEL);
		if (!data) {
			nlmclnt_freegrantargs(call);
			return 0;
		}
		call->a_args.lock.oh.data = (u8 *) data;
	}

	memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
	return 1;
}

void
nlmclnt_freegrantargs(struct nlm_rqst *call)
{
	struct file_lock *fl = &call->a_args.lock.fl;
	/*
	 * Check whether we allocated memory for the owner.
	 */
	if (call->a_args.lock.oh.data != (u8 *) call->a_owner) {
		kfree(call->a_args.lock.oh.data);
	}
	if (fl->fl_ops && fl->fl_ops->fl_release_private)
		fl->fl_ops->fl_release_private(fl);
}

/*
 * This is the main entry point for the NLM client.
 */
int
nlmclnt_proc(struct inode *inode, int cmd, struct file_lock *fl)
{
	struct nfs_server	*nfssrv = NFS_SERVER(inode);
	struct nlm_host		*host;
	struct nlm_rqst		reqst, *call = &reqst;
	sigset_t		oldset;
	unsigned long		flags;
	int			status, proto, vers;

	vers = (NFS_PROTO(inode)->version == 3) ? 4 : 1;
	if (NFS_PROTO(inode)->version > 3) {
		printk(KERN_NOTICE "NFSv4 file locking not implemented!\n");
		return -ENOLCK;
	}

	/* Retrieve transport protocol from NFS client */
	proto = NFS_CLIENT(inode)->cl_xprt->prot;

	if (!(host = nlmclnt_lookup_host(NFS_ADDR(inode), proto, vers)))
		return -ENOLCK;

	/* Create RPC client handle if not there, and copy soft
	 * and intr flags from NFS client. */
	if (host->h_rpcclnt == NULL) {
		struct rpc_clnt	*clnt;

		/* Bind an rpc client to this host handle (does not
		 * perform a portmapper lookup) */
		if (!(clnt = nlm_bind_host(host))) {
			status = -ENOLCK;
			goto done;
		}
		clnt->cl_softrtry = nfssrv->client->cl_softrtry;
		clnt->cl_intr     = nfssrv->client->cl_intr;
		clnt->cl_chatty   = nfssrv->client->cl_chatty;
	}

	/* Keep the old signal mask */
	spin_lock_irqsave(&current->sighand->siglock, flags);
	oldset = current->blocked;

	/* If we're cleaning up locks because the process is exiting,
	 * perform the RPC call asynchronously. */
	if ((IS_SETLK(cmd) || IS_SETLKW(cmd))
	    && fl->fl_type == F_UNLCK
	    && (current->flags & PF_EXITING)) {
		sigfillset(&current->blocked);	/* Mask all signals */
		recalc_sigpending();
		spin_unlock_irqrestore(&current->sighand->siglock, flags);

		call = nlmclnt_alloc_call();
		if (!call) {
			status = -ENOMEM;
			goto out_restore;
		}
		call->a_flags = RPC_TASK_ASYNC;
	} else {
		spin_unlock_irqrestore(&current->sighand->siglock, flags);
		memset(call, 0, sizeof(*call));
		locks_init_lock(&call->a_args.lock.fl);
		locks_init_lock(&call->a_res.lock.fl);
	}
	call->a_host = host;

	nlmclnt_locks_init_private(fl, host);

	/* Set up the argument struct */
	nlmclnt_setlockargs(call, fl);

	if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
		if (fl->fl_type != F_UNLCK) {
			call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
			status = nlmclnt_lock(call, fl);
		} else
			status = nlmclnt_unlock(call, fl);
	} else if (IS_GETLK(cmd))
		status = nlmclnt_test(call, fl);
	else
		status = -EINVAL;

 out_restore:
	spin_lock_irqsave(&current->sighand->siglock, flags);
	current->blocked = oldset;
	recalc_sigpending();
	spin_unlock_irqrestore(&current->sighand->siglock, flags);

done:
	dprintk("lockd: clnt proc returns %d\n", status);
	nlm_release_host(host);
	return status;
}
EXPORT_SYMBOL(nlmclnt_proc);

/*
 * Allocate an NLM RPC call struct
 */
struct nlm_rqst *
nlmclnt_alloc_call(void)
{
	struct nlm_rqst	*call;

	while (!signalled()) {
		call = (struct nlm_rqst *) kmalloc(sizeof(struct nlm_rqst), GFP_KERNEL);
		if (call) {
			memset(call, 0, sizeof(*call));
			locks_init_lock(&call->a_args.lock.fl);
			locks_init_lock(&call->a_res.lock.fl);
			return call;
		}
		printk("nlmclnt_alloc_call: failed, waiting for memory\n");
		current->state = TASK_INTERRUPTIBLE;
		schedule_timeout(5*HZ);
	}
	return NULL;
}

static int nlm_wait_on_grace(wait_queue_head_t *queue)
{
	DEFINE_WAIT(wait);
	int status = -EINTR;

	prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
	if (!signalled ()) {
		schedule_timeout(NLMCLNT_GRACE_WAIT);
		try_to_freeze(PF_FREEZE);
		if (!signalled ())
			status = 0;
	}
	finish_wait(queue, &wait);
	return status;
}

/*
 * Generic NLM call
 */
static int
nlmclnt_call(struct nlm_rqst *req, u32 proc)
{
	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 rpc_message msg = {
		.rpc_argp	= argp,
		.rpc_resp	= resp,
	};
	int		status;

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

	do {
		if (host->h_reclaiming && !argp->reclaim)
			goto in_grace_period;

		/* If we have no RPC client yet, create one. */
		if ((clnt = nlm_bind_host(host)) == NULL)
			return -ENOLCK;
		msg.rpc_proc = &clnt->cl_procinfo[proc];

		/* Perform the RPC call. If an error occurs, try again */
		if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
			dprintk("lockd: rpc_call returned error %d\n", -status);
			switch (status) {
			case -EPROTONOSUPPORT:
				status = -EINVAL;
				break;
			case -ECONNREFUSED:
			case -ETIMEDOUT:
			case -ENOTCONN:
				nlm_rebind_host(host);
				status = -EAGAIN;
				break;
			case -ERESTARTSYS:
				return signalled () ? -EINTR : status;
			default:
				break;
			}
			break;
		} else
		if (resp->status == NLM_LCK_DENIED_GRACE_PERIOD) {
			dprintk("lockd: server in grace period\n");
			if (argp->reclaim) {
				printk(KERN_WARNING
				     "lockd: spurious grace period reject?!\n");
				return -ENOLCK;
			}
		} else {
			if (!argp->reclaim) {
				/* We appear to be out of the grace period */
				wake_up_all(&host->h_gracewait);
			}
			dprintk("lockd: server returns status %d\n", resp->status);
			return 0;	/* Okay, call complete */
		}

in_grace_period:
		/*
		 * The server has rebooted and appears to be in the grace
		 * period during which locks are only allowed to be
		 * reclaimed.
		 * We can only back off and try again later.
		 */
		status = nlm_wait_on_grace(&host->h_gracewait);
	} while (status == 0);

	return status;
}

/*
 * Generic NLM call, async version.
 */
int
nlmsvc_async_call(struct nlm_rqst *req, u32 proc, rpc_action callback)
{
	struct nlm_host	*host = req->a_host;
	struct rpc_clnt	*clnt;
	struct rpc_message msg = {
		.rpc_argp	= &req->a_args,
		.rpc_resp	= &req->a_res,
	};
	int		status;

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

	/* If we have no RPC client yet, create one. */
	if ((clnt = nlm_bind_host(host)) == NULL)
		return -ENOLCK;
	msg.rpc_proc = &clnt->cl_procinfo[proc];

        /* bootstrap and kick off the async RPC call */
        status = rpc_call_async(clnt, &msg, RPC_TASK_ASYNC, callback, req);

	return status;
}

static int
nlmclnt_async_call(struct nlm_rqst *req, u32 proc, rpc_action callback)
{
	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 rpc_message msg = {
		.rpc_argp	= argp,
		.rpc_resp	= resp,
	};
	int		status;

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

	/* If we have no RPC client yet, create one. */
	if ((clnt = nlm_bind_host(host)) == NULL)
		return -ENOLCK;
	msg.rpc_proc = &clnt->cl_procinfo[proc];

	/* Increment host refcount */
	nlm_get_host(host);
        /* bootstrap and kick off the async RPC call */
        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;

	status = nlmclnt_call(req, NLMPROC_TEST);
	nlmclnt_release_lockargs(req);
	if (status < 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.
		 */
		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_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
	memcpy(&new->fl_u.nfs_fl, &fl->fl_u.nfs_fl, sizeof(new->fl_u.nfs_fl));
	nlm_get_lockowner(new->fl_u.nfs_fl.owner);
}

static void nlmclnt_locks_release_private(struct file_lock *fl)
{
	nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
	fl->fl_ops = NULL;
}

static struct file_lock_operations nlmclnt_lock_ops = {
	.fl_copy_lock = nlmclnt_locks_copy_lock,
	.fl_release_private = nlmclnt_locks_release_private,
};

static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
{
	BUG_ON(fl->fl_ops != NULL);
	fl->fl_u.nfs_fl.state = 0;
	fl->fl_u.nfs_fl.flags = 0;
	fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
	fl->fl_ops = &nlmclnt_lock_ops;
}

static void do_vfs_lock(struct file_lock *fl)
{
	int res = 0;
	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
		case FL_POSIX:
			res = posix_lock_file_wait(fl->fl_file, fl);
			break;
		case FL_FLOCK:
			res = flock_lock_file_wait(fl->fl_file, fl);
			break;
		default:
			BUG();
	}
	if (res < 0)
		printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n",
				__FUNCTION__);
}

/*
 * 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;
557 558
	long timeout;
	int status;
L
Linus Torvalds 已提交
559 560 561 562 563 564 565 566

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

567 568
	if (req->a_args.block) {
		status = nlmclnt_prepare_block(req, host, fl);
L
Linus Torvalds 已提交
569 570
		if (status < 0)
			goto out;
571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592
	}
	for(;;) {
		status = nlmclnt_call(req, NLMPROC_LOCK);
		if (status < 0)
			goto out_unblock;
		if (resp->status != NLM_LCK_BLOCKED)
			break;
		/* Wait on an NLM blocking lock */
		timeout = nlmclnt_block(req, NLMCLNT_POLL_TIMEOUT);
		/* Did a reclaimer thread notify us of a server reboot? */
		if (resp->status ==  NLM_LCK_DENIED_GRACE_PERIOD)
			continue;
		if (resp->status != NLM_LCK_BLOCKED)
			break;
		if (timeout >= 0)
			continue;
		/* We were interrupted. Send a CANCEL request to the server
		 * and exit
		 */
		status = (int)timeout;
		goto out_unblock;
	}
L
Linus Torvalds 已提交
593 594 595 596 597 598 599 600

	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_flags |= FL_SLEEP;
		do_vfs_lock(fl);
	}
	status = nlm_stat_to_errno(resp->status);
601 602 603 604 605
out_unblock:
	nlmclnt_finish_block(req);
	/* Cancel the blocked request if it is still pending */
	if (resp->status == NLM_LCK_BLOCKED)
		nlmclnt_cancel(host, fl);
L
Linus Torvalds 已提交
606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844
out:
	nlmclnt_release_lockargs(req);
	return 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) {
		status = nlmclnt_async_call(req, NLMPROC_UNLOCK,
					nlmclnt_unlock_callback);
		/* Hrmf... Do the unlock early since locks_remove_posix()
		 * really expects us to free the lock synchronously */
		do_vfs_lock(fl);
		if (status < 0) {
			nlmclnt_release_lockargs(req);
			kfree(req);
		}
		return status;
	}

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

	do_vfs_lock(fl);
	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);
	nlmclnt_release_lockargs(req);
	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->sighand->siglock, flags);
	oldset = current->blocked;
	sigfillset(&current->blocked);
	recalc_sigpending();
	spin_unlock_irqrestore(&current->sighand->siglock, 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) {
		nlmclnt_release_lockargs(req);
		kfree(req);
	}

	spin_lock_irqsave(&current->sighand->siglock, flags);
	current->blocked = oldset;
	recalc_sigpending();
	spin_unlock_irqrestore(&current->sighand->siglock, 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);
	nlmclnt_release_lockargs(req);
	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;
}