xref: /netbsd-src/sys/kern/vfs_lockf.c (revision ce0bb6e8d2e560ecacbe865a848624f94498063b)
1 /*	$NetBSD: vfs_lockf.c,v 1.6 1995/03/19 23:45:03 mycroft Exp $	*/
2 
3 /*
4  * Copyright (c) 1982, 1986, 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Scooter Morris at Genentech Inc.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *	@(#)ufs_lockf.c	8.3 (Berkeley) 1/6/94
39  */
40 
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/kernel.h>
44 #include <sys/file.h>
45 #include <sys/proc.h>
46 #include <sys/vnode.h>
47 #include <sys/malloc.h>
48 #include <sys/fcntl.h>
49 #include <sys/lockf.h>
50 
51 /*
52  * This variable controls the maximum number of processes that will
53  * be checked in doing deadlock detection.
54  */
55 int maxlockdepth = MAXDEPTH;
56 
57 #ifdef LOCKF_DEBUG
58 int	lockf_debug = 0;
59 #endif
60 
61 #define NOLOCKF (struct lockf *)0
62 #define SELF	0x1
63 #define OTHERS	0x2
64 
65 /*
66  * Do an advisory lock operation.
67  */
68 int
69 lf_advlock(head, size, id, op, fl, flags)
70 	struct lockf **head;
71 	off_t size;
72 	caddr_t id;
73 	int op;
74 	register struct flock *fl;
75 	int flags;
76 {
77 	register struct lockf *lock;
78 	off_t start, end;
79 	int error;
80 
81 	/*
82 	 * Avoid the common case of unlocking when inode has no locks.
83 	 */
84 	if (*head == (struct lockf *)0) {
85 		if (op != F_SETLK) {
86 			fl->l_type = F_UNLCK;
87 			return (0);
88 		}
89 	}
90 	/*
91 	 * Convert the flock structure into a start and end.
92 	 */
93 	switch (fl->l_whence) {
94 
95 	case SEEK_SET:
96 	case SEEK_CUR:
97 		/*
98 		 * Caller is responsible for adding any necessary offset
99 		 * when SEEK_CUR is used.
100 		 */
101 		start = fl->l_start;
102 		break;
103 
104 	case SEEK_END:
105 		start = size + fl->l_start;
106 		break;
107 
108 	default:
109 		return (EINVAL);
110 	}
111 	if (start < 0)
112 		return (EINVAL);
113 	if (fl->l_len == 0)
114 		end = -1;
115 	else
116 		end = start + fl->l_len - 1;
117 	/*
118 	 * Create the lockf structure.
119 	 */
120 	MALLOC(lock, struct lockf *, sizeof *lock, M_LOCKF, M_WAITOK);
121 	lock->lf_start = start;
122 	lock->lf_end = end;
123 	lock->lf_id = id;
124 	lock->lf_head = head;
125 	lock->lf_type = fl->l_type;
126 	lock->lf_next = (struct lockf *)0;
127 	lock->lf_block = (struct lockf *)0;
128 	lock->lf_flags = flags;
129 	/*
130 	 * Do the requested operation.
131 	 */
132 	switch (op) {
133 
134 	case F_SETLK:
135 		return (lf_setlock(lock));
136 
137 	case F_UNLCK:
138 		error = lf_clearlock(lock);
139 		FREE(lock, M_LOCKF);
140 		return (error);
141 
142 	case F_GETLK:
143 		error = lf_getlock(lock, fl);
144 		FREE(lock, M_LOCKF);
145 		return (error);
146 
147 	default:
148 		FREE(lock, M_LOCKF);
149 		return (EINVAL);
150 	}
151 	/* NOTREACHED */
152 }
153 
154 /*
155  * Set a byte-range lock.
156  */
157 int
158 lf_setlock(lock)
159 	register struct lockf *lock;
160 {
161 	register struct lockf *block;
162 	struct lockf **head = lock->lf_head;
163 	struct lockf **prev, *overlap, *ltmp;
164 	static char lockstr[] = "lockf";
165 	int ovcase, priority, needtolink, error;
166 
167 #ifdef LOCKF_DEBUG
168 	if (lockf_debug & 1)
169 		lf_print("lf_setlock", lock);
170 #endif /* LOCKF_DEBUG */
171 
172 	/*
173 	 * Set the priority
174 	 */
175 	priority = PLOCK;
176 	if (lock->lf_type == F_WRLCK)
177 		priority += 4;
178 	priority |= PCATCH;
179 	/*
180 	 * Scan lock list for this file looking for locks that would block us.
181 	 */
182 	while (block = lf_getblock(lock)) {
183 		/*
184 		 * Free the structure and return if nonblocking.
185 		 */
186 		if ((lock->lf_flags & F_WAIT) == 0) {
187 			FREE(lock, M_LOCKF);
188 			return (EAGAIN);
189 		}
190 		/*
191 		 * We are blocked. Since flock style locks cover
192 		 * the whole file, there is no chance for deadlock.
193 		 * For byte-range locks we must check for deadlock.
194 		 *
195 		 * Deadlock detection is done by looking through the
196 		 * wait channels to see if there are any cycles that
197 		 * involve us. MAXDEPTH is set just to make sure we
198 		 * do not go off into neverland.
199 		 */
200 		if ((lock->lf_flags & F_POSIX) &&
201 		    (block->lf_flags & F_POSIX)) {
202 			register struct proc *wproc;
203 			register struct lockf *waitblock;
204 			int i = 0;
205 
206 			/* The block is waiting on something */
207 			wproc = (struct proc *)block->lf_id;
208 			while (wproc->p_wchan &&
209 			       (wproc->p_wmesg == lockstr) &&
210 			       (i++ < maxlockdepth)) {
211 				waitblock = (struct lockf *)wproc->p_wchan;
212 				/* Get the owner of the blocking lock */
213 				waitblock = waitblock->lf_next;
214 				if ((waitblock->lf_flags & F_POSIX) == 0)
215 					break;
216 				wproc = (struct proc *)waitblock->lf_id;
217 				if (wproc == (struct proc *)lock->lf_id) {
218 					free(lock, M_LOCKF);
219 					return (EDEADLK);
220 				}
221 			}
222 		}
223 		/*
224 		 * For flock type locks, we must first remove
225 		 * any shared locks that we hold before we sleep
226 		 * waiting for an exclusive lock.
227 		 */
228 		if ((lock->lf_flags & F_FLOCK) &&
229 		    lock->lf_type == F_WRLCK) {
230 			lock->lf_type = F_UNLCK;
231 			(void) lf_clearlock(lock);
232 			lock->lf_type = F_WRLCK;
233 		}
234 		/*
235 		 * Add our lock to the blocked list and sleep until we're free.
236 		 * Remember who blocked us (for deadlock detection).
237 		 */
238 		lock->lf_next = block;
239 		lf_addblock(block, lock);
240 #ifdef LOCKF_DEBUG
241 		if (lockf_debug & 1) {
242 			lf_print("lf_setlock: blocking on", block);
243 			lf_printlist("lf_setlock", block);
244 		}
245 #endif /* LOCKF_DEBUG */
246 		if (error = tsleep((caddr_t)lock, priority, lockstr, 0)) {
247 			/*
248 			 * Delete ourselves from the waiting to lock list.
249 			 */
250 			for (block = lock->lf_next;
251 			     block != NOLOCKF;
252 			     block = block->lf_block) {
253 				if (block->lf_block != lock)
254 					continue;
255 				block->lf_block = block->lf_block->lf_block;
256 				break;
257 			}
258 			/*
259 			 * If we did not find ourselves on the list, but
260 			 * are still linked onto a lock list, then something
261 			 * is very wrong.
262 			 */
263 			if (block == NOLOCKF && lock->lf_next != NOLOCKF)
264 				panic("lf_setlock: lost lock");
265 			free(lock, M_LOCKF);
266 			return (error);
267 		}
268 	}
269 	/*
270 	 * No blocks!!  Add the lock.  Note that we will
271 	 * downgrade or upgrade any overlapping locks this
272 	 * process already owns.
273 	 *
274 	 * Skip over locks owned by other processes.
275 	 * Handle any locks that overlap and are owned by ourselves.
276 	 */
277 	prev = head;
278 	block = *head;
279 	needtolink = 1;
280 	for (;;) {
281 		if (ovcase = lf_findoverlap(block, lock, SELF, &prev, &overlap))
282 			block = overlap->lf_next;
283 		/*
284 		 * Six cases:
285 		 *	0) no overlap
286 		 *	1) overlap == lock
287 		 *	2) overlap contains lock
288 		 *	3) lock contains overlap
289 		 *	4) overlap starts before lock
290 		 *	5) overlap ends after lock
291 		 */
292 		switch (ovcase) {
293 		case 0: /* no overlap */
294 			if (needtolink) {
295 				*prev = lock;
296 				lock->lf_next = overlap;
297 			}
298 			break;
299 
300 		case 1: /* overlap == lock */
301 			/*
302 			 * If downgrading lock, others may be
303 			 * able to acquire it.
304 			 */
305 			if (lock->lf_type == F_RDLCK &&
306 			    overlap->lf_type == F_WRLCK)
307 				lf_wakelock(overlap);
308 			overlap->lf_type = lock->lf_type;
309 			FREE(lock, M_LOCKF);
310 			lock = overlap; /* for debug output below */
311 			break;
312 
313 		case 2: /* overlap contains lock */
314 			/*
315 			 * Check for common starting point and different types.
316 			 */
317 			if (overlap->lf_type == lock->lf_type) {
318 				free(lock, M_LOCKF);
319 				lock = overlap; /* for debug output below */
320 				break;
321 			}
322 			if (overlap->lf_start == lock->lf_start) {
323 				*prev = lock;
324 				lock->lf_next = overlap;
325 				overlap->lf_start = lock->lf_end + 1;
326 			} else
327 				lf_split(overlap, lock);
328 			lf_wakelock(overlap);
329 			break;
330 
331 		case 3: /* lock contains overlap */
332 			/*
333 			 * If downgrading lock, others may be able to
334 			 * acquire it, otherwise take the list.
335 			 */
336 			if (lock->lf_type == F_RDLCK &&
337 			    overlap->lf_type == F_WRLCK) {
338 				lf_wakelock(overlap);
339 			} else {
340 				ltmp = lock->lf_block;
341 				lock->lf_block = overlap->lf_block;
342 				lf_addblock(lock, ltmp);
343 			}
344 			/*
345 			 * Add the new lock if necessary and delete the overlap.
346 			 */
347 			if (needtolink) {
348 				*prev = lock;
349 				lock->lf_next = overlap->lf_next;
350 				prev = &lock->lf_next;
351 				needtolink = 0;
352 			} else
353 				*prev = overlap->lf_next;
354 			free(overlap, M_LOCKF);
355 			continue;
356 
357 		case 4: /* overlap starts before lock */
358 			/*
359 			 * Add lock after overlap on the list.
360 			 */
361 			lock->lf_next = overlap->lf_next;
362 			overlap->lf_next = lock;
363 			overlap->lf_end = lock->lf_start - 1;
364 			prev = &lock->lf_next;
365 			lf_wakelock(overlap);
366 			needtolink = 0;
367 			continue;
368 
369 		case 5: /* overlap ends after lock */
370 			/*
371 			 * Add the new lock before overlap.
372 			 */
373 			if (needtolink) {
374 				*prev = lock;
375 				lock->lf_next = overlap;
376 			}
377 			overlap->lf_start = lock->lf_end + 1;
378 			lf_wakelock(overlap);
379 			break;
380 		}
381 		break;
382 	}
383 #ifdef LOCKF_DEBUG
384 	if (lockf_debug & 1) {
385 		lf_print("lf_setlock: got the lock", lock);
386 		lf_printlist("lf_setlock", lock);
387 	}
388 #endif /* LOCKF_DEBUG */
389 	return (0);
390 }
391 
392 /*
393  * Remove a byte-range lock on an inode.
394  *
395  * Generally, find the lock (or an overlap to that lock)
396  * and remove it (or shrink it), then wakeup anyone we can.
397  */
398 int
399 lf_clearlock(unlock)
400 	register struct lockf *unlock;
401 {
402 	struct lockf **head = unlock->lf_head;
403 	register struct lockf *lf = *head;
404 	struct lockf *overlap, **prev;
405 	int ovcase;
406 
407 	if (lf == NOLOCKF)
408 		return (0);
409 #ifdef LOCKF_DEBUG
410 	if (unlock->lf_type != F_UNLCK)
411 		panic("lf_clearlock: bad type");
412 	if (lockf_debug & 1)
413 		lf_print("lf_clearlock", unlock);
414 #endif /* LOCKF_DEBUG */
415 	prev = head;
416 	while (ovcase = lf_findoverlap(lf, unlock, SELF, &prev, &overlap)) {
417 		/*
418 		 * Wakeup the list of locks to be retried.
419 		 */
420 		lf_wakelock(overlap);
421 
422 		switch (ovcase) {
423 
424 		case 1: /* overlap == lock */
425 			*prev = overlap->lf_next;
426 			FREE(overlap, M_LOCKF);
427 			break;
428 
429 		case 2: /* overlap contains lock: split it */
430 			if (overlap->lf_start == unlock->lf_start) {
431 				overlap->lf_start = unlock->lf_end + 1;
432 				break;
433 			}
434 			lf_split(overlap, unlock);
435 			overlap->lf_next = unlock->lf_next;
436 			break;
437 
438 		case 3: /* lock contains overlap */
439 			*prev = overlap->lf_next;
440 			lf = overlap->lf_next;
441 			free(overlap, M_LOCKF);
442 			continue;
443 
444 		case 4: /* overlap starts before lock */
445 			overlap->lf_end = unlock->lf_start - 1;
446 			prev = &overlap->lf_next;
447 			lf = overlap->lf_next;
448 			continue;
449 
450 		case 5: /* overlap ends after lock */
451 			overlap->lf_start = unlock->lf_end + 1;
452 			break;
453 		}
454 		break;
455 	}
456 #ifdef LOCKF_DEBUG
457 	if (lockf_debug & 1)
458 		lf_printlist("lf_clearlock", unlock);
459 #endif /* LOCKF_DEBUG */
460 	return (0);
461 }
462 
463 /*
464  * Check whether there is a blocking lock,
465  * and if so return its process identifier.
466  */
467 int
468 lf_getlock(lock, fl)
469 	register struct lockf *lock;
470 	register struct flock *fl;
471 {
472 	register struct lockf *block;
473 
474 #ifdef LOCKF_DEBUG
475 	if (lockf_debug & 1)
476 		lf_print("lf_getlock", lock);
477 #endif /* LOCKF_DEBUG */
478 
479 	if (block = lf_getblock(lock)) {
480 		fl->l_type = block->lf_type;
481 		fl->l_whence = SEEK_SET;
482 		fl->l_start = block->lf_start;
483 		if (block->lf_end == -1)
484 			fl->l_len = 0;
485 		else
486 			fl->l_len = block->lf_end - block->lf_start + 1;
487 		if (block->lf_flags & F_POSIX)
488 			fl->l_pid = ((struct proc *)(block->lf_id))->p_pid;
489 		else
490 			fl->l_pid = -1;
491 	} else {
492 		fl->l_type = F_UNLCK;
493 	}
494 	return (0);
495 }
496 
497 /*
498  * Walk the list of locks for an inode and
499  * return the first blocking lock.
500  */
501 struct lockf *
502 lf_getblock(lock)
503 	register struct lockf *lock;
504 {
505 	struct lockf **prev, *overlap, *lf = *(lock->lf_head);
506 	int ovcase;
507 
508 	prev = lock->lf_head;
509 	while (ovcase = lf_findoverlap(lf, lock, OTHERS, &prev, &overlap)) {
510 		/*
511 		 * We've found an overlap, see if it blocks us
512 		 */
513 		if ((lock->lf_type == F_WRLCK || overlap->lf_type == F_WRLCK))
514 			return (overlap);
515 		/*
516 		 * Nope, point to the next one on the list and
517 		 * see if it blocks us
518 		 */
519 		lf = overlap->lf_next;
520 	}
521 	return (NOLOCKF);
522 }
523 
524 /*
525  * Walk the list of locks for an inode to
526  * find an overlapping lock (if any).
527  *
528  * NOTE: this returns only the FIRST overlapping lock.  There
529  *	 may be more than one.
530  */
531 int
532 lf_findoverlap(lf, lock, type, prev, overlap)
533 	register struct lockf *lf;
534 	struct lockf *lock;
535 	int type;
536 	struct lockf ***prev;
537 	struct lockf **overlap;
538 {
539 	off_t start, end;
540 
541 	*overlap = lf;
542 	if (lf == NOLOCKF)
543 		return (0);
544 #ifdef LOCKF_DEBUG
545 	if (lockf_debug & 2)
546 		lf_print("lf_findoverlap: looking for overlap in", lock);
547 #endif /* LOCKF_DEBUG */
548 	start = lock->lf_start;
549 	end = lock->lf_end;
550 	while (lf != NOLOCKF) {
551 		if (((type & SELF) && lf->lf_id != lock->lf_id) ||
552 		    ((type & OTHERS) && lf->lf_id == lock->lf_id)) {
553 			*prev = &lf->lf_next;
554 			*overlap = lf = lf->lf_next;
555 			continue;
556 		}
557 #ifdef LOCKF_DEBUG
558 		if (lockf_debug & 2)
559 			lf_print("\tchecking", lf);
560 #endif /* LOCKF_DEBUG */
561 		/*
562 		 * OK, check for overlap
563 		 *
564 		 * Six cases:
565 		 *	0) no overlap
566 		 *	1) overlap == lock
567 		 *	2) overlap contains lock
568 		 *	3) lock contains overlap
569 		 *	4) overlap starts before lock
570 		 *	5) overlap ends after lock
571 		 */
572 		if ((lf->lf_end != -1 && start > lf->lf_end) ||
573 		    (end != -1 && lf->lf_start > end)) {
574 			/* Case 0 */
575 #ifdef LOCKF_DEBUG
576 			if (lockf_debug & 2)
577 				printf("no overlap\n");
578 #endif /* LOCKF_DEBUG */
579 			if ((type & SELF) && end != -1 && lf->lf_start > end)
580 				return (0);
581 			*prev = &lf->lf_next;
582 			*overlap = lf = lf->lf_next;
583 			continue;
584 		}
585 		if ((lf->lf_start == start) && (lf->lf_end == end)) {
586 			/* Case 1 */
587 #ifdef LOCKF_DEBUG
588 			if (lockf_debug & 2)
589 				printf("overlap == lock\n");
590 #endif /* LOCKF_DEBUG */
591 			return (1);
592 		}
593 		if ((lf->lf_start <= start) &&
594 		    (end != -1) &&
595 		    ((lf->lf_end >= end) || (lf->lf_end == -1))) {
596 			/* Case 2 */
597 #ifdef LOCKF_DEBUG
598 			if (lockf_debug & 2)
599 				printf("overlap contains lock\n");
600 #endif /* LOCKF_DEBUG */
601 			return (2);
602 		}
603 		if (start <= lf->lf_start &&
604 		           (end == -1 ||
605 			   (lf->lf_end != -1 && end >= lf->lf_end))) {
606 			/* Case 3 */
607 #ifdef LOCKF_DEBUG
608 			if (lockf_debug & 2)
609 				printf("lock contains overlap\n");
610 #endif /* LOCKF_DEBUG */
611 			return (3);
612 		}
613 		if ((lf->lf_start < start) &&
614 			((lf->lf_end >= start) || (lf->lf_end == -1))) {
615 			/* Case 4 */
616 #ifdef LOCKF_DEBUG
617 			if (lockf_debug & 2)
618 				printf("overlap starts before lock\n");
619 #endif /* LOCKF_DEBUG */
620 			return (4);
621 		}
622 		if ((lf->lf_start > start) &&
623 			(end != -1) &&
624 			((lf->lf_end > end) || (lf->lf_end == -1))) {
625 			/* Case 5 */
626 #ifdef LOCKF_DEBUG
627 			if (lockf_debug & 2)
628 				printf("overlap ends after lock\n");
629 #endif /* LOCKF_DEBUG */
630 			return (5);
631 		}
632 		panic("lf_findoverlap: default");
633 	}
634 	return (0);
635 }
636 
637 /*
638  * Add a lock to the end of the blocked list.
639  */
640 void
641 lf_addblock(lock, blocked)
642 	struct lockf *lock;
643 	struct lockf *blocked;
644 {
645 	register struct lockf *lf;
646 
647 	if (blocked == NOLOCKF)
648 		return;
649 #ifdef LOCKF_DEBUG
650 	if (lockf_debug & 2) {
651 		lf_print("addblock: adding", blocked);
652 		lf_print("to blocked list of", lock);
653 	}
654 #endif /* LOCKF_DEBUG */
655 	if ((lf = lock->lf_block) == NOLOCKF) {
656 		lock->lf_block = blocked;
657 		return;
658 	}
659 	while (lf->lf_block != NOLOCKF)
660 		lf = lf->lf_block;
661 	lf->lf_block = blocked;
662 	return;
663 }
664 
665 /*
666  * Split a lock and a contained region into
667  * two or three locks as necessary.
668  */
669 void
670 lf_split(lock1, lock2)
671 	register struct lockf *lock1;
672 	register struct lockf *lock2;
673 {
674 	register struct lockf *splitlock;
675 
676 #ifdef LOCKF_DEBUG
677 	if (lockf_debug & 2) {
678 		lf_print("lf_split", lock1);
679 		lf_print("splitting from", lock2);
680 	}
681 #endif /* LOCKF_DEBUG */
682 	/*
683 	 * Check to see if spliting into only two pieces.
684 	 */
685 	if (lock1->lf_start == lock2->lf_start) {
686 		lock1->lf_start = lock2->lf_end + 1;
687 		lock2->lf_next = lock1;
688 		return;
689 	}
690 	if (lock1->lf_end == lock2->lf_end) {
691 		lock1->lf_end = lock2->lf_start - 1;
692 		lock2->lf_next = lock1->lf_next;
693 		lock1->lf_next = lock2;
694 		return;
695 	}
696 	/*
697 	 * Make a new lock consisting of the last part of
698 	 * the encompassing lock
699 	 */
700 	MALLOC(splitlock, struct lockf *, sizeof *splitlock, M_LOCKF, M_WAITOK);
701 	bcopy((caddr_t)lock1, (caddr_t)splitlock, sizeof *splitlock);
702 	splitlock->lf_start = lock2->lf_end + 1;
703 	splitlock->lf_block = NOLOCKF;
704 	lock1->lf_end = lock2->lf_start - 1;
705 	/*
706 	 * OK, now link it in
707 	 */
708 	splitlock->lf_next = lock1->lf_next;
709 	lock2->lf_next = splitlock;
710 	lock1->lf_next = lock2;
711 }
712 
713 /*
714  * Wakeup a blocklist
715  */
716 void
717 lf_wakelock(listhead)
718 	struct lockf *listhead;
719 {
720 	register struct lockf *blocklist, *wakelock;
721 
722 	blocklist = listhead->lf_block;
723 	listhead->lf_block = NOLOCKF;
724 	while (blocklist != NOLOCKF) {
725 		wakelock = blocklist;
726 		blocklist = blocklist->lf_block;
727 		wakelock->lf_block = NOLOCKF;
728 		wakelock->lf_next = NOLOCKF;
729 #ifdef LOCKF_DEBUG
730 		if (lockf_debug & 2)
731 			lf_print("lf_wakelock: awakening", wakelock);
732 #endif /* LOCKF_DEBUG */
733 		wakeup((caddr_t)wakelock);
734 	}
735 }
736 
737 #ifdef LOCKF_DEBUG
738 /*
739  * Print out a lock.
740  */
741 void
742 lf_print(tag, lock)
743 	char *tag;
744 	register struct lockf *lock;
745 {
746 
747 	printf("%s: lock %p for ", tag, lock);
748 	if (lock->lf_flags & F_POSIX)
749 		printf("proc %d", ((struct proc *)(lock->lf_id))->p_pid);
750 	else
751 		printf("id 0x%x", lock->lf_id);
752 	printf(" in ino %d on dev <%d, %d>, %s, start %d, end %d",
753 		lock->lf_inode->i_number,
754 		major(lock->lf_inode->i_dev),
755 		minor(lock->lf_inode->i_dev),
756 		lock->lf_type == F_RDLCK ? "shared" :
757 		lock->lf_type == F_WRLCK ? "exclusive" :
758 		lock->lf_type == F_UNLCK ? "unlock" :
759 		"unknown", lock->lf_start, lock->lf_end);
760 	if (lock->lf_block)
761 		printf(" block %p\n", lock->lf_block);
762 	else
763 		printf("\n");
764 }
765 
766 void
767 lf_printlist(tag, lock)
768 	char *tag;
769 	struct lockf *lock;
770 {
771 	register struct lockf *lf;
772 
773 	printf("%s: Lock list for ino %d on dev <%d, %d>:\n",
774 		tag, lock->lf_inode->i_number,
775 		major(lock->lf_inode->i_dev),
776 		minor(lock->lf_inode->i_dev));
777 	for (lf = lock->lf_inode->i_lockf; lf; lf = lf->lf_next) {
778 		printf("\tlock %p for ", lf);
779 		if (lf->lf_flags & F_POSIX)
780 			printf("proc %d", ((struct proc *)(lf->lf_id))->p_pid);
781 		else
782 			printf("id 0x%x", lf->lf_id);
783 		printf(", %s, start %d, end %d",
784 			lf->lf_type == F_RDLCK ? "shared" :
785 			lf->lf_type == F_WRLCK ? "exclusive" :
786 			lf->lf_type == F_UNLCK ? "unlock" :
787 			"unknown", lf->lf_start, lf->lf_end);
788 		if (lf->lf_block)
789 			printf(" block %p\n", lf->lf_block);
790 		else
791 			printf("\n");
792 	}
793 }
794 #endif /* LOCKF_DEBUG */
795