xref: /netbsd-src/sys/kern/vfs_lockf.c (revision 3b01aba77a7a698587faaae455bbfe740923c1f5)
1 /*	$NetBSD: vfs_lockf.c,v 1.17 2000/07/22 15:26:13 jdolecek 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	8.4 (Berkeley) 10/26/94
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  * XXX TODO
67  * Misc cleanups: "caddr_t id" should be visible in the API as a
68  * "struct proc *".
69  * (This requires rototilling all VFS's which support advisory locking).
70  *
71  * Use pools for lock allocation.
72  */
73 
74 /*
75  * XXXSMP TODO: Using either (a) a global lock, or (b) the vnode's
76  * interlock should be sufficient; (b) requires a change to the API
77  * because the vnode isn't visible here.
78  *
79  * If there's a lot of lock contention on a single vnode, locking
80  * schemes which allow for more paralleism would be needed.  Given how
81  * infrequently byte-range locks are actually used in typical BSD
82  * code, a more complex approach probably isn't worth it.
83  */
84 
85 /*
86  * Do an advisory lock operation.
87  */
88 int
89 lf_advlock(ap, head, size)
90 	struct vop_advlock_args *ap;
91 	struct lockf **head;
92 	off_t size;
93 {
94 	struct flock *fl = ap->a_fl;
95 	struct lockf *lock;
96 	off_t start, end;
97 	int error;
98 
99 	/*
100 	 * Convert the flock structure into a start and end.
101 	 */
102 	switch (fl->l_whence) {
103 	case SEEK_SET:
104 	case SEEK_CUR:
105 		/*
106 		 * Caller is responsible for adding any necessary offset
107 		 * when SEEK_CUR is used.
108 		 */
109 		start = fl->l_start;
110 		break;
111 
112 	case SEEK_END:
113 		start = size + fl->l_start;
114 		break;
115 
116 	default:
117 		return (EINVAL);
118 	}
119 	if (start < 0)
120 		return (EINVAL);
121 
122 	/*
123 	 * Avoid the common case of unlocking when inode has no locks.
124 	 */
125 	if (*head == (struct lockf *)0) {
126 		if (ap->a_op != F_SETLK) {
127 			fl->l_type = F_UNLCK;
128 			return (0);
129 		}
130 	}
131 
132 	if (fl->l_len == 0)
133 		end = -1;
134 	else
135 		end = start + fl->l_len - 1;
136 	/*
137 	 * Create the lockf structure.
138 	 */
139 	MALLOC(lock, struct lockf *, sizeof(*lock), M_LOCKF, M_WAITOK);
140 	lock->lf_start = start;
141 	lock->lf_end = end;
142 	lock->lf_id = ap->a_id;
143 	lock->lf_head = head;
144 	lock->lf_type = fl->l_type;
145 	lock->lf_next = (struct lockf *)0;
146 	TAILQ_INIT(&lock->lf_blkhd);
147 	lock->lf_flags = ap->a_flags;
148 	/*
149 	 * Do the requested operation.
150 	 */
151 	switch (ap->a_op) {
152 
153 	case F_SETLK:
154 		return (lf_setlock(lock));
155 
156 	case F_UNLCK:
157 		error = lf_clearlock(lock);
158 		FREE(lock, M_LOCKF);
159 		return (error);
160 
161 	case F_GETLK:
162 		error = lf_getlock(lock, fl);
163 		FREE(lock, M_LOCKF);
164 		return (error);
165 
166 	default:
167 		FREE(lock, M_LOCKF);
168 		return (EINVAL);
169 	}
170 	/* NOTREACHED */
171 }
172 
173 /*
174  * Set a byte-range lock.
175  */
176 int
177 lf_setlock(lock)
178 	struct lockf *lock;
179 {
180 	struct lockf *block;
181 	struct lockf **head = lock->lf_head;
182 	struct lockf **prev, *overlap, *ltmp;
183 	static char lockstr[] = "lockf";
184 	int ovcase, priority, needtolink, error;
185 
186 #ifdef LOCKF_DEBUG
187 	if (lockf_debug & 1)
188 		lf_print("lf_setlock", lock);
189 #endif /* LOCKF_DEBUG */
190 
191 	/*
192 	 * Set the priority
193 	 */
194 	priority = PLOCK;
195 	if (lock->lf_type == F_WRLCK)
196 		priority += 4;
197 	priority |= PCATCH;
198 	/*
199 	 * Scan lock list for this file looking for locks that would block us.
200 	 */
201 	while ((block = lf_getblock(lock)) != NULL) {
202 		/*
203 		 * Free the structure and return if nonblocking.
204 		 */
205 		if ((lock->lf_flags & F_WAIT) == 0) {
206 			FREE(lock, M_LOCKF);
207 			return (EAGAIN);
208 		}
209 		/*
210 		 * We are blocked. Since flock style locks cover
211 		 * the whole file, there is no chance for deadlock.
212 		 * For byte-range locks we must check for deadlock.
213 		 *
214 		 * Deadlock detection is done by looking through the
215 		 * wait channels to see if there are any cycles that
216 		 * involve us. MAXDEPTH is set just to make sure we
217 		 * do not go off into neverneverland.
218 		 */
219 		if ((lock->lf_flags & F_POSIX) &&
220 		    (block->lf_flags & F_POSIX)) {
221 			struct proc *wproc;
222 			struct lockf *waitblock;
223 			int i = 0;
224 
225 			/* The block is waiting on something */
226 			wproc = (struct proc *)block->lf_id;
227 			while (wproc->p_wchan &&
228 			       (wproc->p_wmesg == lockstr) &&
229 			       (i++ < maxlockdepth)) {
230 				waitblock = (struct lockf *)wproc->p_wchan;
231 				/* Get the owner of the blocking lock */
232 				waitblock = waitblock->lf_next;
233 				if ((waitblock->lf_flags & F_POSIX) == 0)
234 					break;
235 				wproc = (struct proc *)waitblock->lf_id;
236 				if (wproc == (struct proc *)lock->lf_id) {
237 					free(lock, M_LOCKF);
238 					return (EDEADLK);
239 				}
240 			}
241 			/*
242 			 * If we're still following a dependancy chain
243 			 * after maxlockdepth iterations, assume we're in
244 			 * a cycle to be safe.
245 			 */
246 			if (i >= maxlockdepth) {
247 				free(lock, M_LOCKF);
248 				return (EDEADLK);
249 			}
250 		}
251 		/*
252 		 * For flock type locks, we must first remove
253 		 * any shared locks that we hold before we sleep
254 		 * waiting for an exclusive lock.
255 		 */
256 		if ((lock->lf_flags & F_FLOCK) &&
257 		    lock->lf_type == F_WRLCK) {
258 			lock->lf_type = F_UNLCK;
259 			(void) lf_clearlock(lock);
260 			lock->lf_type = F_WRLCK;
261 		}
262 		/*
263 		 * Add our lock to the blocked list and sleep until we're free.
264 		 * Remember who blocked us (for deadlock detection).
265 		 */
266 		lock->lf_next = block;
267 		TAILQ_INSERT_TAIL(&block->lf_blkhd, lock, lf_block);
268 #ifdef LOCKF_DEBUG
269 		if (lockf_debug & 1) {
270 			lf_print("lf_setlock: blocking on", block);
271 			lf_printlist("lf_setlock", block);
272 		}
273 #endif /* LOCKF_DEBUG */
274 		error = tsleep((caddr_t)lock, priority, lockstr, 0);
275 
276 		/*
277 		 * We may have been awakened by a signal (in
278 		 * which case we must remove ourselves from the
279 		 * blocked list) and/or by another process
280 		 * releasing a lock (in which case we have already
281 		 * been removed from the blocked list and our
282 		 * lf_next field set to NOLOCKF).
283 		 */
284 		if (lock->lf_next != NOLOCKF) {
285 			TAILQ_REMOVE(&lock->lf_next->lf_blkhd, lock, lf_block);
286 			lock->lf_next = NOLOCKF;
287 		}
288 		if (error) {
289 			free(lock, M_LOCKF);
290 			return (error);
291 		}
292 	}
293 	/*
294 	 * No blocks!!  Add the lock.  Note that we will
295 	 * downgrade or upgrade any overlapping locks this
296 	 * process already owns.
297 	 *
298 	 * Skip over locks owned by other processes.
299 	 * Handle any locks that overlap and are owned by ourselves.
300 	 */
301 	prev = head;
302 	block = *head;
303 	needtolink = 1;
304 	for (;;) {
305 		ovcase = lf_findoverlap(block, lock, SELF, &prev, &overlap);
306 		if (ovcase)
307 			block = overlap->lf_next;
308 		/*
309 		 * Six cases:
310 		 *	0) no overlap
311 		 *	1) overlap == lock
312 		 *	2) overlap contains lock
313 		 *	3) lock contains overlap
314 		 *	4) overlap starts before lock
315 		 *	5) overlap ends after lock
316 		 */
317 		switch (ovcase) {
318 		case 0: /* no overlap */
319 			if (needtolink) {
320 				*prev = lock;
321 				lock->lf_next = overlap;
322 			}
323 			break;
324 
325 		case 1: /* overlap == lock */
326 			/*
327 			 * If downgrading lock, others may be
328 			 * able to acquire it.
329 			 */
330 			if (lock->lf_type == F_RDLCK &&
331 			    overlap->lf_type == F_WRLCK)
332 				lf_wakelock(overlap);
333 			overlap->lf_type = lock->lf_type;
334 			FREE(lock, M_LOCKF);
335 			lock = overlap; /* for debug output below */
336 			break;
337 
338 		case 2: /* overlap contains lock */
339 			/*
340 			 * Check for common starting point and different types.
341 			 */
342 			if (overlap->lf_type == lock->lf_type) {
343 				free(lock, M_LOCKF);
344 				lock = overlap; /* for debug output below */
345 				break;
346 			}
347 			if (overlap->lf_start == lock->lf_start) {
348 				*prev = lock;
349 				lock->lf_next = overlap;
350 				overlap->lf_start = lock->lf_end + 1;
351 			} else
352 				lf_split(overlap, lock);
353 			lf_wakelock(overlap);
354 			break;
355 
356 		case 3: /* lock contains overlap */
357 			/*
358 			 * If downgrading lock, others may be able to
359 			 * acquire it, otherwise take the list.
360 			 */
361 			if (lock->lf_type == F_RDLCK &&
362 			    overlap->lf_type == F_WRLCK) {
363 				lf_wakelock(overlap);
364 			} else {
365 				while ((ltmp = overlap->lf_blkhd.tqh_first)) {
366 					KASSERT(ltmp->lf_next == overlap);
367 					TAILQ_REMOVE(&overlap->lf_blkhd, ltmp,
368 					    lf_block);
369 					ltmp->lf_next = lock;
370 					TAILQ_INSERT_TAIL(&lock->lf_blkhd,
371 					    ltmp, lf_block);
372 				}
373 			}
374 			/*
375 			 * Add the new lock if necessary and delete the overlap.
376 			 */
377 			if (needtolink) {
378 				*prev = lock;
379 				lock->lf_next = overlap->lf_next;
380 				prev = &lock->lf_next;
381 				needtolink = 0;
382 			} else
383 				*prev = overlap->lf_next;
384 			free(overlap, M_LOCKF);
385 			continue;
386 
387 		case 4: /* overlap starts before lock */
388 			/*
389 			 * Add lock after overlap on the list.
390 			 */
391 			lock->lf_next = overlap->lf_next;
392 			overlap->lf_next = lock;
393 			overlap->lf_end = lock->lf_start - 1;
394 			prev = &lock->lf_next;
395 			lf_wakelock(overlap);
396 			needtolink = 0;
397 			continue;
398 
399 		case 5: /* overlap ends after lock */
400 			/*
401 			 * Add the new lock before overlap.
402 			 */
403 			if (needtolink) {
404 				*prev = lock;
405 				lock->lf_next = overlap;
406 			}
407 			overlap->lf_start = lock->lf_end + 1;
408 			lf_wakelock(overlap);
409 			break;
410 		}
411 		break;
412 	}
413 #ifdef LOCKF_DEBUG
414 	if (lockf_debug & 1) {
415 		lf_print("lf_setlock: got the lock", lock);
416 		lf_printlist("lf_setlock", lock);
417 	}
418 #endif /* LOCKF_DEBUG */
419 	return (0);
420 }
421 
422 /*
423  * Remove a byte-range lock on an inode.
424  *
425  * Generally, find the lock (or an overlap to that lock)
426  * and remove it (or shrink it), then wakeup anyone we can.
427  */
428 int
429 lf_clearlock(unlock)
430 	struct lockf *unlock;
431 {
432 	struct lockf **head = unlock->lf_head;
433 	struct lockf *lf = *head;
434 	struct lockf *overlap, **prev;
435 	int ovcase;
436 
437 	if (lf == NOLOCKF)
438 		return (0);
439 #ifdef LOCKF_DEBUG
440 	if (unlock->lf_type != F_UNLCK)
441 		panic("lf_clearlock: bad type");
442 	if (lockf_debug & 1)
443 		lf_print("lf_clearlock", unlock);
444 #endif /* LOCKF_DEBUG */
445 	prev = head;
446 	while ((ovcase = lf_findoverlap(lf, unlock, SELF,
447 					&prev, &overlap)) != 0) {
448 		/*
449 		 * Wakeup the list of locks to be retried.
450 		 */
451 		lf_wakelock(overlap);
452 
453 		switch (ovcase) {
454 
455 		case 1: /* overlap == lock */
456 			*prev = overlap->lf_next;
457 			FREE(overlap, M_LOCKF);
458 			break;
459 
460 		case 2: /* overlap contains lock: split it */
461 			if (overlap->lf_start == unlock->lf_start) {
462 				overlap->lf_start = unlock->lf_end + 1;
463 				break;
464 			}
465 			lf_split(overlap, unlock);
466 			overlap->lf_next = unlock->lf_next;
467 			break;
468 
469 		case 3: /* lock contains overlap */
470 			*prev = overlap->lf_next;
471 			lf = overlap->lf_next;
472 			free(overlap, M_LOCKF);
473 			continue;
474 
475 		case 4: /* overlap starts before lock */
476 			overlap->lf_end = unlock->lf_start - 1;
477 			prev = &overlap->lf_next;
478 			lf = overlap->lf_next;
479 			continue;
480 
481 		case 5: /* overlap ends after lock */
482 			overlap->lf_start = unlock->lf_end + 1;
483 			break;
484 		}
485 		break;
486 	}
487 #ifdef LOCKF_DEBUG
488 	if (lockf_debug & 1)
489 		lf_printlist("lf_clearlock", unlock);
490 #endif /* LOCKF_DEBUG */
491 	return (0);
492 }
493 
494 /*
495  * Check whether there is a blocking lock,
496  * and if so return its process identifier.
497  */
498 int
499 lf_getlock(lock, fl)
500 	struct lockf *lock;
501 	struct flock *fl;
502 {
503 	struct lockf *block;
504 
505 #ifdef LOCKF_DEBUG
506 	if (lockf_debug & 1)
507 		lf_print("lf_getlock", lock);
508 #endif /* LOCKF_DEBUG */
509 
510 	if ((block = lf_getblock(lock)) != NULL) {
511 		fl->l_type = block->lf_type;
512 		fl->l_whence = SEEK_SET;
513 		fl->l_start = block->lf_start;
514 		if (block->lf_end == -1)
515 			fl->l_len = 0;
516 		else
517 			fl->l_len = block->lf_end - block->lf_start + 1;
518 		if (block->lf_flags & F_POSIX)
519 			fl->l_pid = ((struct proc *)(block->lf_id))->p_pid;
520 		else
521 			fl->l_pid = -1;
522 	} else {
523 		fl->l_type = F_UNLCK;
524 	}
525 	return (0);
526 }
527 
528 /*
529  * Walk the list of locks for an inode and
530  * return the first blocking lock.
531  */
532 struct lockf *
533 lf_getblock(lock)
534 	struct lockf *lock;
535 {
536 	struct lockf **prev, *overlap, *lf = *(lock->lf_head);
537 	int ovcase;
538 
539 	prev = lock->lf_head;
540 	while ((ovcase = lf_findoverlap(lf, lock, OTHERS,
541 					&prev, &overlap)) != 0) {
542 		/*
543 		 * We've found an overlap, see if it blocks us
544 		 */
545 		if ((lock->lf_type == F_WRLCK || overlap->lf_type == F_WRLCK))
546 			return (overlap);
547 		/*
548 		 * Nope, point to the next one on the list and
549 		 * see if it blocks us
550 		 */
551 		lf = overlap->lf_next;
552 	}
553 	return (NOLOCKF);
554 }
555 
556 /*
557  * Walk the list of locks for an inode to
558  * find an overlapping lock (if any).
559  *
560  * NOTE: this returns only the FIRST overlapping lock.  There
561  *	 may be more than one.
562  */
563 int
564 lf_findoverlap(lf, lock, type, prev, overlap)
565 	struct lockf *lf;
566 	struct lockf *lock;
567 	int type;
568 	struct lockf ***prev;
569 	struct lockf **overlap;
570 {
571 	off_t start, end;
572 
573 	*overlap = lf;
574 	if (lf == NOLOCKF)
575 		return (0);
576 #ifdef LOCKF_DEBUG
577 	if (lockf_debug & 2)
578 		lf_print("lf_findoverlap: looking for overlap in", lock);
579 #endif /* LOCKF_DEBUG */
580 	start = lock->lf_start;
581 	end = lock->lf_end;
582 	while (lf != NOLOCKF) {
583 		if (((type & SELF) && lf->lf_id != lock->lf_id) ||
584 		    ((type & OTHERS) && lf->lf_id == lock->lf_id)) {
585 			*prev = &lf->lf_next;
586 			*overlap = lf = lf->lf_next;
587 			continue;
588 		}
589 #ifdef LOCKF_DEBUG
590 		if (lockf_debug & 2)
591 			lf_print("\tchecking", lf);
592 #endif /* LOCKF_DEBUG */
593 		/*
594 		 * OK, check for overlap
595 		 *
596 		 * Six cases:
597 		 *	0) no overlap
598 		 *	1) overlap == lock
599 		 *	2) overlap contains lock
600 		 *	3) lock contains overlap
601 		 *	4) overlap starts before lock
602 		 *	5) overlap ends after lock
603 		 */
604 		if ((lf->lf_end != -1 && start > lf->lf_end) ||
605 		    (end != -1 && lf->lf_start > end)) {
606 			/* Case 0 */
607 #ifdef LOCKF_DEBUG
608 			if (lockf_debug & 2)
609 				printf("no overlap\n");
610 #endif /* LOCKF_DEBUG */
611 			if ((type & SELF) && end != -1 && lf->lf_start > end)
612 				return (0);
613 			*prev = &lf->lf_next;
614 			*overlap = lf = lf->lf_next;
615 			continue;
616 		}
617 		if ((lf->lf_start == start) && (lf->lf_end == end)) {
618 			/* Case 1 */
619 #ifdef LOCKF_DEBUG
620 			if (lockf_debug & 2)
621 				printf("overlap == lock\n");
622 #endif /* LOCKF_DEBUG */
623 			return (1);
624 		}
625 		if ((lf->lf_start <= start) &&
626 		    (end != -1) &&
627 		    ((lf->lf_end >= end) || (lf->lf_end == -1))) {
628 			/* Case 2 */
629 #ifdef LOCKF_DEBUG
630 			if (lockf_debug & 2)
631 				printf("overlap contains lock\n");
632 #endif /* LOCKF_DEBUG */
633 			return (2);
634 		}
635 		if (start <= lf->lf_start &&
636 		           (end == -1 ||
637 			   (lf->lf_end != -1 && end >= lf->lf_end))) {
638 			/* Case 3 */
639 #ifdef LOCKF_DEBUG
640 			if (lockf_debug & 2)
641 				printf("lock contains overlap\n");
642 #endif /* LOCKF_DEBUG */
643 			return (3);
644 		}
645 		if ((lf->lf_start < start) &&
646 			((lf->lf_end >= start) || (lf->lf_end == -1))) {
647 			/* Case 4 */
648 #ifdef LOCKF_DEBUG
649 			if (lockf_debug & 2)
650 				printf("overlap starts before lock\n");
651 #endif /* LOCKF_DEBUG */
652 			return (4);
653 		}
654 		if ((lf->lf_start > start) &&
655 			(end != -1) &&
656 			((lf->lf_end > end) || (lf->lf_end == -1))) {
657 			/* Case 5 */
658 #ifdef LOCKF_DEBUG
659 			if (lockf_debug & 2)
660 				printf("overlap ends after lock\n");
661 #endif /* LOCKF_DEBUG */
662 			return (5);
663 		}
664 		panic("lf_findoverlap: default");
665 	}
666 	return (0);
667 }
668 
669 /*
670  * Split a lock and a contained region into
671  * two or three locks as necessary.
672  */
673 void
674 lf_split(lock1, lock2)
675 	struct lockf *lock1;
676 	struct lockf *lock2;
677 {
678 	struct lockf *splitlock;
679 
680 #ifdef LOCKF_DEBUG
681 	if (lockf_debug & 2) {
682 		lf_print("lf_split", lock1);
683 		lf_print("splitting from", lock2);
684 	}
685 #endif /* LOCKF_DEBUG */
686 	/*
687 	 * Check to see if spliting into only two pieces.
688 	 */
689 	if (lock1->lf_start == lock2->lf_start) {
690 		lock1->lf_start = lock2->lf_end + 1;
691 		lock2->lf_next = lock1;
692 		return;
693 	}
694 	if (lock1->lf_end == lock2->lf_end) {
695 		lock1->lf_end = lock2->lf_start - 1;
696 		lock2->lf_next = lock1->lf_next;
697 		lock1->lf_next = lock2;
698 		return;
699 	}
700 	/*
701 	 * Make a new lock consisting of the last part of
702 	 * the encompassing lock
703 	 */
704 	MALLOC(splitlock, struct lockf *, sizeof(*splitlock), M_LOCKF, M_WAITOK);
705 	memcpy((caddr_t)splitlock, (caddr_t)lock1, sizeof(*splitlock));
706 	splitlock->lf_start = lock2->lf_end + 1;
707 	TAILQ_INIT(&splitlock->lf_blkhd);
708 	lock1->lf_end = lock2->lf_start - 1;
709 	/*
710 	 * OK, now link it in
711 	 */
712 	splitlock->lf_next = lock1->lf_next;
713 	lock2->lf_next = splitlock;
714 	lock1->lf_next = lock2;
715 }
716 
717 /*
718  * Wakeup a blocklist
719  */
720 void
721 lf_wakelock(listhead)
722 	struct lockf *listhead;
723 {
724 	struct lockf *wakelock;
725 
726 	while ((wakelock = listhead->lf_blkhd.tqh_first)) {
727 		KASSERT(wakelock->lf_next == listhead);
728 		TAILQ_REMOVE(&listhead->lf_blkhd, wakelock, lf_block);
729 		wakelock->lf_next = NOLOCKF;
730 #ifdef LOCKF_DEBUG
731 		if (lockf_debug & 2)
732 			lf_print("lf_wakelock: awakening", wakelock);
733 #endif
734 		wakeup((caddr_t)wakelock);
735 	}
736 }
737 
738 #ifdef LOCKF_DEBUG
739 /*
740  * Print out a lock.
741  */
742 void
743 lf_print(tag, lock)
744 	char *tag;
745 	struct lockf *lock;
746 {
747 
748 	printf("%s: lock %p for ", tag, lock);
749 	if (lock->lf_flags & F_POSIX)
750 		printf("proc %d", ((struct proc *)(lock->lf_id))->p_pid);
751 	else
752 		printf("id 0x%p", lock->lf_id);
753 	printf(" %s, start %qx, end %qx",
754 		lock->lf_type == F_RDLCK ? "shared" :
755 		lock->lf_type == F_WRLCK ? "exclusive" :
756 		lock->lf_type == F_UNLCK ? "unlock" :
757 		"unknown", lock->lf_start, lock->lf_end);
758 	if (lock->lf_blkhd.tqh_first)
759 		printf(" block %p\n", lock->lf_blkhd.tqh_first);
760 	else
761 		printf("\n");
762 }
763 
764 void
765 lf_printlist(tag, lock)
766 	char *tag;
767 	struct lockf *lock;
768 {
769 	struct lockf *lf, *blk;
770 
771 	printf("%s: Lock list:\n", tag);
772 	for (lf = *lock->lf_head; lf; lf = lf->lf_next) {
773 		printf("\tlock %p for ", lf);
774 		if (lf->lf_flags & F_POSIX)
775 			printf("proc %d", ((struct proc *)(lf->lf_id))->p_pid);
776 		else
777 			printf("id 0x%p", lf->lf_id);
778 		printf(", %s, start %qx, end %qx",
779 			lf->lf_type == F_RDLCK ? "shared" :
780 			lf->lf_type == F_WRLCK ? "exclusive" :
781 			lf->lf_type == F_UNLCK ? "unlock" :
782 			"unknown", lf->lf_start, lf->lf_end);
783 		for (blk = lf->lf_blkhd.tqh_first; blk;
784 		     blk = blk->lf_block.tqe_next) {
785 			if (blk->lf_flags & F_POSIX)
786 				printf("proc %d",
787 				    ((struct proc *)(blk->lf_id))->p_pid);
788 			else
789 				printf("id 0x%p", blk->lf_id);
790 			printf(", %s, start %qx, end %qx",
791 				blk->lf_type == F_RDLCK ? "shared" :
792 				blk->lf_type == F_WRLCK ? "exclusive" :
793 				blk->lf_type == F_UNLCK ? "unlock" :
794 				"unknown", blk->lf_start, blk->lf_end);
795 			if (blk->lf_blkhd.tqh_first)
796 				 panic("lf_printlist: bad list");
797 		}
798 		printf("\n");
799 	}
800 }
801 #endif /* LOCKF_DEBUG */
802