xref: /freebsd/sys/kern/kern_lockf.c (revision e627b39baccd1ec9129690167cf5e6d860509655)
1 /*
2  * Copyright (c) 1982, 1986, 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Scooter Morris at Genentech Inc.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  *	@(#)ufs_lockf.c	8.3 (Berkeley) 1/6/94
37  * $Id: kern_lockf.c,v 1.5 1995/12/14 08:31:26 phk Exp $
38  */
39 
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/kernel.h>
43 #include <sys/proc.h>
44 #include <sys/unistd.h>
45 #include <sys/vnode.h>
46 #include <sys/malloc.h>
47 #include <sys/fcntl.h>
48 
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 static void	 lf_addblock __P((struct lockf *, struct lockf *));
65 static int	 lf_clearlock __P((struct lockf *));
66 static int	 lf_findoverlap __P((struct lockf *,
67 	    struct lockf *, int, struct lockf ***, struct lockf **));
68 static struct lockf *
69 	 lf_getblock __P((struct lockf *));
70 static int	 lf_getlock __P((struct lockf *, struct flock *));
71 static int	 lf_setlock __P((struct lockf *));
72 static void	 lf_split __P((struct lockf *, struct lockf *));
73 static void	 lf_wakelock __P((struct lockf *));
74 
75 /*
76  * Advisory record locking support
77  */
78 int
79 lf_advlock(ap, head, size)
80 	struct vop_advlock_args /* {
81 		struct vnode *a_vp;
82 		caddr_t  a_id;
83 		int  a_op;
84 		struct flock *a_fl;
85 		int  a_flags;
86 	} */ *ap;
87 	struct lockf **head;
88 	u_quad_t size;
89 {
90 	register struct flock *fl = ap->a_fl;
91 	register struct lockf *lock;
92 	off_t start, end;
93 	int error;
94 
95 	/*
96 	 * Avoid the common case of unlocking when inode has no locks.
97 	 */
98 	if (*head == (struct lockf *)0) {
99 		if (ap->a_op != F_SETLK) {
100 			fl->l_type = F_UNLCK;
101 			return (0);
102 		}
103 	}
104 	/*
105 	 * Convert the flock structure into a start and end.
106 	 */
107 	switch (fl->l_whence) {
108 
109 	case SEEK_SET:
110 	case SEEK_CUR:
111 		/*
112 		 * Caller is responsible for adding any necessary offset
113 		 * when SEEK_CUR is used.
114 		 */
115 		start = fl->l_start;
116 		break;
117 
118 	case SEEK_END:
119 		start = size + fl->l_start;
120 		break;
121 
122 	default:
123 		return (EINVAL);
124 	}
125 	if (start < 0)
126 		return (EINVAL);
127 	if (fl->l_len == 0)
128 		end = -1;
129 	else
130 		end = start + fl->l_len - 1;
131 	/*
132 	 * Create the lockf structure
133 	 */
134 	MALLOC(lock, struct lockf *, sizeof *lock, M_LOCKF, M_WAITOK);
135 	lock->lf_start = start;
136 	lock->lf_end = end;
137 	lock->lf_id = ap->a_id;
138 	lock->lf_head = head;
139 	lock->lf_type = fl->l_type;
140 	lock->lf_next = (struct lockf *)0;
141 	lock->lf_block = (struct lockf *)0;
142 	lock->lf_flags = ap->a_flags;
143 	/*
144 	 * Do the requested operation.
145 	 */
146 	switch(ap->a_op) {
147 	case F_SETLK:
148 		return (lf_setlock(lock));
149 
150 	case F_UNLCK:
151 		error = lf_clearlock(lock);
152 		FREE(lock, M_LOCKF);
153 		return (error);
154 
155 	case F_GETLK:
156 		error = lf_getlock(lock, fl);
157 		FREE(lock, M_LOCKF);
158 		return (error);
159 
160 	default:
161 		free(lock, M_LOCKF);
162 		return (EINVAL);
163 	}
164 	/* NOTREACHED */
165 }
166 
167 /*
168  * Set a byte-range lock.
169  */
170 static int
171 lf_setlock(lock)
172 	register struct lockf *lock;
173 {
174 	register struct lockf *block;
175 	struct lockf **head = lock->lf_head;
176 	struct lockf **prev, *overlap, *ltmp;
177 	static char lockstr[] = "lockf";
178 	int ovcase, priority, needtolink, error;
179 
180 #ifdef LOCKF_DEBUG
181 	if (lockf_debug & 1)
182 		lf_print("lf_setlock", lock);
183 #endif /* LOCKF_DEBUG */
184 
185 	/*
186 	 * Set the priority
187 	 */
188 	priority = PLOCK;
189 	if (lock->lf_type == F_WRLCK)
190 		priority += 4;
191 	priority |= PCATCH;
192 	/*
193 	 * Scan lock list for this file looking for locks that would block us.
194 	 */
195 	while ((block = lf_getblock(lock))) {
196 		/*
197 		 * Free the structure and return if nonblocking.
198 		 */
199 		if ((lock->lf_flags & F_WAIT) == 0) {
200 			FREE(lock, M_LOCKF);
201 			return (EAGAIN);
202 		}
203 		/*
204 		 * We are blocked. Since flock style locks cover
205 		 * the whole file, there is no chance for deadlock.
206 		 * For byte-range locks we must check for deadlock.
207 		 *
208 		 * Deadlock detection is done by looking through the
209 		 * wait channels to see if there are any cycles that
210 		 * involve us. MAXDEPTH is set just to make sure we
211 		 * do not go off into neverland.
212 		 */
213 		if ((lock->lf_flags & F_POSIX) &&
214 		    (block->lf_flags & F_POSIX)) {
215 			register struct proc *wproc;
216 			register struct lockf *waitblock;
217 			int i = 0;
218 
219 			/* The block is waiting on something */
220 			wproc = (struct proc *)block->lf_id;
221 			while (wproc->p_wchan &&
222 			       (wproc->p_wmesg == lockstr) &&
223 			       (i++ < maxlockdepth)) {
224 				waitblock = (struct lockf *)wproc->p_wchan;
225 				/* Get the owner of the blocking lock */
226 				waitblock = waitblock->lf_next;
227 				if ((waitblock->lf_flags & F_POSIX) == 0)
228 					break;
229 				wproc = (struct proc *)waitblock->lf_id;
230 				if (wproc == (struct proc *)lock->lf_id) {
231 					free(lock, M_LOCKF);
232 					return (EDEADLK);
233 				}
234 			}
235 		}
236 		/*
237 		 * For flock type locks, we must first remove
238 		 * any shared locks that we hold before we sleep
239 		 * waiting for an exclusive lock.
240 		 */
241 		if ((lock->lf_flags & F_FLOCK) &&
242 		    lock->lf_type == F_WRLCK) {
243 			lock->lf_type = F_UNLCK;
244 			(void) lf_clearlock(lock);
245 			lock->lf_type = F_WRLCK;
246 		}
247 		/*
248 		 * Add our lock to the blocked list and sleep until we're free.
249 		 * Remember who blocked us (for deadlock detection).
250 		 */
251 		lock->lf_next = block;
252 		lf_addblock(block, lock);
253 #ifdef LOCKF_DEBUG
254 		if (lockf_debug & 1) {
255 			lf_print("lf_setlock: blocking on", block);
256 			lf_printlist("lf_setlock", block);
257 		}
258 #endif /* LOCKF_DEBUG */
259 		if ((error = tsleep((caddr_t)lock, priority, lockstr, 0))) {
260 			/*
261 			 * Delete ourselves from the waiting to lock list.
262 			 */
263 			for (block = lock->lf_next;
264 			     block != NOLOCKF;
265 			     block = block->lf_block) {
266 				if (block->lf_block != lock)
267 					continue;
268 				block->lf_block = block->lf_block->lf_block;
269 				break;
270 			}
271 			/*
272 			 * If we did not find ourselves on the list, but
273 			 * are still linked onto a lock list, then something
274 			 * is very wrong.
275 			 */
276 			if (block == NOLOCKF && lock->lf_next != NOLOCKF)
277 				panic("lf_setlock: lost lock");
278 			free(lock, M_LOCKF);
279 			return (error);
280 		}
281 	}
282 	/*
283 	 * No blocks!!  Add the lock.  Note that we will
284 	 * downgrade or upgrade any overlapping locks this
285 	 * process already owns.
286 	 *
287 	 * Skip over locks owned by other processes.
288 	 * Handle any locks that overlap and are owned by ourselves.
289 	 */
290 	prev = head;
291 	block = *head;
292 	needtolink = 1;
293 	for (;;) {
294 		ovcase = lf_findoverlap(block, lock, SELF, &prev, &overlap);
295 		if (ovcase)
296 			block = overlap->lf_next;
297 		/*
298 		 * Six cases:
299 		 *	0) no overlap
300 		 *	1) overlap == lock
301 		 *	2) overlap contains lock
302 		 *	3) lock contains overlap
303 		 *	4) overlap starts before lock
304 		 *	5) overlap ends after lock
305 		 */
306 		switch (ovcase) {
307 		case 0: /* no overlap */
308 			if (needtolink) {
309 				*prev = lock;
310 				lock->lf_next = overlap;
311 			}
312 			break;
313 
314 		case 1: /* overlap == lock */
315 			/*
316 			 * If downgrading lock, others may be
317 			 * able to acquire it.
318 			 */
319 			if (lock->lf_type == F_RDLCK &&
320 			    overlap->lf_type == F_WRLCK)
321 				lf_wakelock(overlap);
322 			overlap->lf_type = lock->lf_type;
323 			FREE(lock, M_LOCKF);
324 			lock = overlap; /* for debug output below */
325 			break;
326 
327 		case 2: /* overlap contains lock */
328 			/*
329 			 * Check for common starting point and different types.
330 			 */
331 			if (overlap->lf_type == lock->lf_type) {
332 				free(lock, M_LOCKF);
333 				lock = overlap; /* for debug output below */
334 				break;
335 			}
336 			if (overlap->lf_start == lock->lf_start) {
337 				*prev = lock;
338 				lock->lf_next = overlap;
339 				overlap->lf_start = lock->lf_end + 1;
340 			} else
341 				lf_split(overlap, lock);
342 			lf_wakelock(overlap);
343 			break;
344 
345 		case 3: /* lock contains overlap */
346 			/*
347 			 * If downgrading lock, others may be able to
348 			 * acquire it, otherwise take the list.
349 			 */
350 			if (lock->lf_type == F_RDLCK &&
351 			    overlap->lf_type == F_WRLCK) {
352 				lf_wakelock(overlap);
353 			} else {
354 				ltmp = lock->lf_block;
355 				lock->lf_block = overlap->lf_block;
356 				lf_addblock(lock, ltmp);
357 			}
358 			/*
359 			 * Add the new lock if necessary and delete the overlap.
360 			 */
361 			if (needtolink) {
362 				*prev = lock;
363 				lock->lf_next = overlap->lf_next;
364 				prev = &lock->lf_next;
365 				needtolink = 0;
366 			} else
367 				*prev = overlap->lf_next;
368 			free(overlap, M_LOCKF);
369 			continue;
370 
371 		case 4: /* overlap starts before lock */
372 			/*
373 			 * Add lock after overlap on the list.
374 			 */
375 			lock->lf_next = overlap->lf_next;
376 			overlap->lf_next = lock;
377 			overlap->lf_end = lock->lf_start - 1;
378 			prev = &lock->lf_next;
379 			lf_wakelock(overlap);
380 			needtolink = 0;
381 			continue;
382 
383 		case 5: /* overlap ends after lock */
384 			/*
385 			 * Add the new lock before overlap.
386 			 */
387 			if (needtolink) {
388 				*prev = lock;
389 				lock->lf_next = overlap;
390 			}
391 			overlap->lf_start = lock->lf_end + 1;
392 			lf_wakelock(overlap);
393 			break;
394 		}
395 		break;
396 	}
397 #ifdef LOCKF_DEBUG
398 	if (lockf_debug & 1) {
399 		lf_print("lf_setlock: got the lock", lock);
400 		lf_printlist("lf_setlock", lock);
401 	}
402 #endif /* LOCKF_DEBUG */
403 	return (0);
404 }
405 
406 /*
407  * Remove a byte-range lock on an inode.
408  *
409  * Generally, find the lock (or an overlap to that lock)
410  * and remove it (or shrink it), then wakeup anyone we can.
411  */
412 static int
413 lf_clearlock(unlock)
414 	register struct lockf *unlock;
415 {
416 	struct lockf **head = unlock->lf_head;
417 	register struct lockf *lf = *head;
418 	struct lockf *overlap, **prev;
419 	int ovcase;
420 
421 	if (lf == NOLOCKF)
422 		return (0);
423 #ifdef LOCKF_DEBUG
424 	if (unlock->lf_type != F_UNLCK)
425 		panic("lf_clearlock: bad type");
426 	if (lockf_debug & 1)
427 		lf_print("lf_clearlock", unlock);
428 #endif /* LOCKF_DEBUG */
429 	prev = head;
430 	while ((ovcase = lf_findoverlap(lf, unlock, SELF, &prev, &overlap))) {
431 		/*
432 		 * Wakeup the list of locks to be retried.
433 		 */
434 		lf_wakelock(overlap);
435 
436 		switch (ovcase) {
437 
438 		case 1: /* overlap == lock */
439 			*prev = overlap->lf_next;
440 			FREE(overlap, M_LOCKF);
441 			break;
442 
443 		case 2: /* overlap contains lock: split it */
444 			if (overlap->lf_start == unlock->lf_start) {
445 				overlap->lf_start = unlock->lf_end + 1;
446 				break;
447 			}
448 			lf_split(overlap, unlock);
449 			overlap->lf_next = unlock->lf_next;
450 			break;
451 
452 		case 3: /* lock contains overlap */
453 			*prev = overlap->lf_next;
454 			lf = overlap->lf_next;
455 			free(overlap, M_LOCKF);
456 			continue;
457 
458 		case 4: /* overlap starts before lock */
459 			overlap->lf_end = unlock->lf_start - 1;
460 			prev = &overlap->lf_next;
461 			lf = overlap->lf_next;
462 			continue;
463 
464 		case 5: /* overlap ends after lock */
465 			overlap->lf_start = unlock->lf_end + 1;
466 			break;
467 		}
468 		break;
469 	}
470 #ifdef LOCKF_DEBUG
471 	if (lockf_debug & 1)
472 		lf_printlist("lf_clearlock", unlock);
473 #endif /* LOCKF_DEBUG */
474 	return (0);
475 }
476 
477 /*
478  * Check whether there is a blocking lock,
479  * and if so return its process identifier.
480  */
481 static int
482 lf_getlock(lock, fl)
483 	register struct lockf *lock;
484 	register struct flock *fl;
485 {
486 	register struct lockf *block;
487 
488 #ifdef LOCKF_DEBUG
489 	if (lockf_debug & 1)
490 		lf_print("lf_getlock", lock);
491 #endif /* LOCKF_DEBUG */
492 
493 	if ((block = lf_getblock(lock))) {
494 		fl->l_type = block->lf_type;
495 		fl->l_whence = SEEK_SET;
496 		fl->l_start = block->lf_start;
497 		if (block->lf_end == -1)
498 			fl->l_len = 0;
499 		else
500 			fl->l_len = block->lf_end - block->lf_start + 1;
501 		if (block->lf_flags & F_POSIX)
502 			fl->l_pid = ((struct proc *)(block->lf_id))->p_pid;
503 		else
504 			fl->l_pid = -1;
505 	} else {
506 		fl->l_type = F_UNLCK;
507 	}
508 	return (0);
509 }
510 
511 /*
512  * Walk the list of locks for an inode and
513  * return the first blocking lock.
514  */
515 static struct lockf *
516 lf_getblock(lock)
517 	register struct lockf *lock;
518 {
519 	struct lockf **prev, *overlap, *lf = *(lock->lf_head);
520 	int ovcase;
521 
522 	prev = lock->lf_head;
523 	while ((ovcase = lf_findoverlap(lf, lock, OTHERS, &prev, &overlap))) {
524 		/*
525 		 * We've found an overlap, see if it blocks us
526 		 */
527 		if ((lock->lf_type == F_WRLCK || overlap->lf_type == F_WRLCK))
528 			return (overlap);
529 		/*
530 		 * Nope, point to the next one on the list and
531 		 * see if it blocks us
532 		 */
533 		lf = overlap->lf_next;
534 	}
535 	return (NOLOCKF);
536 }
537 
538 /*
539  * Walk the list of locks for an inode to
540  * find an overlapping lock (if any).
541  *
542  * NOTE: this returns only the FIRST overlapping lock.  There
543  *	 may be more than one.
544  */
545 static int
546 lf_findoverlap(lf, lock, type, prev, overlap)
547 	register struct lockf *lf;
548 	struct lockf *lock;
549 	int type;
550 	struct lockf ***prev;
551 	struct lockf **overlap;
552 {
553 	off_t start, end;
554 
555 	*overlap = lf;
556 	if (lf == NOLOCKF)
557 		return (0);
558 #ifdef LOCKF_DEBUG
559 	if (lockf_debug & 2)
560 		lf_print("lf_findoverlap: looking for overlap in", lock);
561 #endif /* LOCKF_DEBUG */
562 	start = lock->lf_start;
563 	end = lock->lf_end;
564 	while (lf != NOLOCKF) {
565 		if (((type & SELF) && lf->lf_id != lock->lf_id) ||
566 		    ((type & OTHERS) && lf->lf_id == lock->lf_id)) {
567 			*prev = &lf->lf_next;
568 			*overlap = lf = lf->lf_next;
569 			continue;
570 		}
571 #ifdef LOCKF_DEBUG
572 		if (lockf_debug & 2)
573 			lf_print("\tchecking", lf);
574 #endif /* LOCKF_DEBUG */
575 		/*
576 		 * OK, check for overlap
577 		 *
578 		 * Six cases:
579 		 *	0) no overlap
580 		 *	1) overlap == lock
581 		 *	2) overlap contains lock
582 		 *	3) lock contains overlap
583 		 *	4) overlap starts before lock
584 		 *	5) overlap ends after lock
585 		 */
586 		if ((lf->lf_end != -1 && start > lf->lf_end) ||
587 		    (end != -1 && lf->lf_start > end)) {
588 			/* Case 0 */
589 #ifdef LOCKF_DEBUG
590 			if (lockf_debug & 2)
591 				printf("no overlap\n");
592 #endif /* LOCKF_DEBUG */
593 			if ((type & SELF) && end != -1 && lf->lf_start > end)
594 				return (0);
595 			*prev = &lf->lf_next;
596 			*overlap = lf = lf->lf_next;
597 			continue;
598 		}
599 		if ((lf->lf_start == start) && (lf->lf_end == end)) {
600 			/* Case 1 */
601 #ifdef LOCKF_DEBUG
602 			if (lockf_debug & 2)
603 				printf("overlap == lock\n");
604 #endif /* LOCKF_DEBUG */
605 			return (1);
606 		}
607 		if ((lf->lf_start <= start) &&
608 		    (end != -1) &&
609 		    ((lf->lf_end >= end) || (lf->lf_end == -1))) {
610 			/* Case 2 */
611 #ifdef LOCKF_DEBUG
612 			if (lockf_debug & 2)
613 				printf("overlap contains lock\n");
614 #endif /* LOCKF_DEBUG */
615 			return (2);
616 		}
617 		if (start <= lf->lf_start &&
618 		           (end == -1 ||
619 			   (lf->lf_end != -1 && end >= lf->lf_end))) {
620 			/* Case 3 */
621 #ifdef LOCKF_DEBUG
622 			if (lockf_debug & 2)
623 				printf("lock contains overlap\n");
624 #endif /* LOCKF_DEBUG */
625 			return (3);
626 		}
627 		if ((lf->lf_start < start) &&
628 			((lf->lf_end >= start) || (lf->lf_end == -1))) {
629 			/* Case 4 */
630 #ifdef LOCKF_DEBUG
631 			if (lockf_debug & 2)
632 				printf("overlap starts before lock\n");
633 #endif /* LOCKF_DEBUG */
634 			return (4);
635 		}
636 		if ((lf->lf_start > start) &&
637 			(end != -1) &&
638 			((lf->lf_end > end) || (lf->lf_end == -1))) {
639 			/* Case 5 */
640 #ifdef LOCKF_DEBUG
641 			if (lockf_debug & 2)
642 				printf("overlap ends after lock\n");
643 #endif /* LOCKF_DEBUG */
644 			return (5);
645 		}
646 		panic("lf_findoverlap: default");
647 	}
648 	return (0);
649 }
650 
651 /*
652  * Add a lock to the end of the blocked list.
653  */
654 static void
655 lf_addblock(blocklist, lock)
656 	struct lockf *blocklist;
657 	struct lockf *lock;
658 {
659 	register struct lockf *lf;
660 
661 	if (lock == NOLOCKF)
662 		return;
663 #ifdef LOCKF_DEBUG
664 	if (lockf_debug & 2) {
665 		lf_print("addblock: adding", lock);
666 		lf_print("to blocked list of", blocklist);
667 	}
668 #endif /* LOCKF_DEBUG */
669 	if ((lf = blocklist->lf_block) == NOLOCKF) {
670 		blocklist->lf_block = lock;
671 		return;
672 	}
673 	while (lf->lf_block != NOLOCKF)
674 		lf = lf->lf_block;
675 	lf->lf_block = lock;
676 	return;
677 }
678 
679 /*
680  * Split a lock and a contained region into
681  * two or three locks as necessary.
682  */
683 static void
684 lf_split(lock1, lock2)
685 	register struct lockf *lock1;
686 	register struct lockf *lock2;
687 {
688 	register struct lockf *splitlock;
689 
690 #ifdef LOCKF_DEBUG
691 	if (lockf_debug & 2) {
692 		lf_print("lf_split", lock1);
693 		lf_print("splitting from", lock2);
694 	}
695 #endif /* LOCKF_DEBUG */
696 	/*
697 	 * Check to see if spliting into only two pieces.
698 	 */
699 	if (lock1->lf_start == lock2->lf_start) {
700 		lock1->lf_start = lock2->lf_end + 1;
701 		lock2->lf_next = lock1;
702 		return;
703 	}
704 	if (lock1->lf_end == lock2->lf_end) {
705 		lock1->lf_end = lock2->lf_start - 1;
706 		lock2->lf_next = lock1->lf_next;
707 		lock1->lf_next = lock2;
708 		return;
709 	}
710 	/*
711 	 * Make a new lock consisting of the last part of
712 	 * the encompassing lock
713 	 */
714 	MALLOC(splitlock, struct lockf *, sizeof *splitlock, M_LOCKF, M_WAITOK);
715 	bcopy((caddr_t)lock1, (caddr_t)splitlock, sizeof *splitlock);
716 	splitlock->lf_start = lock2->lf_end + 1;
717 	splitlock->lf_block = NOLOCKF;
718 	lock1->lf_end = lock2->lf_start - 1;
719 	/*
720 	 * OK, now link it in
721 	 */
722 	splitlock->lf_next = lock1->lf_next;
723 	lock2->lf_next = splitlock;
724 	lock1->lf_next = lock2;
725 }
726 
727 /*
728  * Wakeup a blocklist
729  */
730 static void
731 lf_wakelock(listhead)
732 	struct lockf *listhead;
733 {
734         register struct lockf *blocklist, *wakelock;
735 
736 	blocklist = listhead->lf_block;
737 	listhead->lf_block = NOLOCKF;
738         while (blocklist != NOLOCKF) {
739                 wakelock = blocklist;
740                 blocklist = blocklist->lf_block;
741 		wakelock->lf_block = NOLOCKF;
742 		wakelock->lf_next = NOLOCKF;
743 #ifdef LOCKF_DEBUG
744 		if (lockf_debug & 2)
745 			lf_print("lf_wakelock: awakening", wakelock);
746 #endif /* LOCKF_DEBUG */
747                 wakeup((caddr_t)wakelock);
748         }
749 }
750 
751 #ifdef LOCKF_DEBUG
752 /*
753  * Print out a lock.
754  */
755 void
756 lf_print(tag, lock)
757 	char *tag;
758 	register struct lockf *lock;
759 {
760 
761 	printf("%s: lock 0x%lx for ", tag, lock);
762 	if (lock->lf_flags & F_POSIX)
763 		printf("proc %d", ((struct proc *)(lock->lf_id))->p_pid);
764 	else
765 		printf("id 0x%x", lock->lf_id);
766 	printf(" in ino %d on dev <%d, %d>, %s, start %d, end %d",
767 		lock->lf_inode->i_number,
768 		major(lock->lf_inode->i_dev),
769 		minor(lock->lf_inode->i_dev),
770 		lock->lf_type == F_RDLCK ? "shared" :
771 		lock->lf_type == F_WRLCK ? "exclusive" :
772 		lock->lf_type == F_UNLCK ? "unlock" :
773 		"unknown", lock->lf_start, lock->lf_end);
774 	if (lock->lf_block)
775 		printf(" block 0x%x\n", lock->lf_block);
776 	else
777 		printf("\n");
778 }
779 
780 void
781 lf_printlist(tag, lock)
782 	char *tag;
783 	struct lockf *lock;
784 {
785 	register struct lockf *lf;
786 
787 	printf("%s: Lock list for ino %d on dev <%d, %d>:\n",
788 		tag, lock->lf_inode->i_number,
789 		major(lock->lf_inode->i_dev),
790 		minor(lock->lf_inode->i_dev));
791 	for (lf = lock->lf_inode->i_lockf; lf; lf = lf->lf_next) {
792 		printf("\tlock 0x%lx for ", lf);
793 		if (lf->lf_flags & F_POSIX)
794 			printf("proc %d", ((struct proc *)(lf->lf_id))->p_pid);
795 		else
796 			printf("id 0x%x", lf->lf_id);
797 		printf(", %s, start %d, end %d",
798 			lf->lf_type == F_RDLCK ? "shared" :
799 			lf->lf_type == F_WRLCK ? "exclusive" :
800 			lf->lf_type == F_UNLCK ? "unlock" :
801 			"unknown", lf->lf_start, lf->lf_end);
802 		if (lf->lf_block)
803 			printf(" block 0x%x\n", lf->lf_block);
804 		else
805 			printf("\n");
806 	}
807 }
808 #endif /* LOCKF_DEBUG */
809