vfs_lockf.c revision 1.1
1/*
2 * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
3 * 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 *	from: @(#)ufs_lockf.c	7.7 (Berkeley) 7/2/91
37 *	$Id: vfs_lockf.c,v 1.1 1994/03/09 21:23:50 ws Exp $
38 */
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/kernel.h>
43#include <sys/file.h>
44#include <sys/proc.h>
45#include <sys/vnode.h>
46#include <sys/malloc.h>
47#include <sys/fcntl.h>
48#include <sys/lockf.h>
49
50
51
52/*
53 * Advisory record locking support
54 */
55lf_advlock(head, size, id, op, fl, flags)
56	struct lockf **head;
57	u_long size;
58	caddr_t id;
59	int op;
60	register struct flock *fl;
61	int flags;
62{
63	register struct lockf *lock;
64	off_t start, end;
65	int error;
66
67	/*
68	 * Avoid the common case of unlocking when inode has no locks.
69	 */
70	if (*head == (struct lockf *)0) {
71		if (op != F_SETLK) {
72			fl->l_type = F_UNLCK;
73			return (0);
74		}
75	}
76
77	/*
78	 * Convert the flock structure into a start and end.
79	 */
80	switch (fl->l_whence) {
81
82	case SEEK_SET:
83	case SEEK_CUR:
84		/*
85		 * Caller is responsible for adding any necessary offset
86		 * when SEEK_CUR is used.
87		 */
88		start = fl->l_start;
89		break;
90
91	case SEEK_END:
92		start = size + fl->l_start;
93		break;
94
95	default:
96		return (EINVAL);
97	}
98	if (start < 0)
99		return (EINVAL);
100	if (fl->l_len == 0)
101		end = -1;
102	else
103		end = start + fl->l_len - 1;
104	/*
105	 * Create the lockf structure
106	 */
107	MALLOC(lock, struct lockf *, sizeof *lock, M_LOCKF, M_WAITOK);
108	lock->lf_start = start;
109	lock->lf_end = end;
110	lock->lf_id = id;
111	lock->lf_head = head;
112	lock->lf_type = fl->l_type;
113	lock->lf_next = (struct lockf *)0;
114	lock->lf_block = (struct lockf *)0;
115	lock->lf_flags = flags;
116	/*
117	 * Do the requested operation.
118	 */
119	switch(op) {
120	case F_SETLK:
121		return (lf_setlock(lock));
122
123	case F_UNLCK:
124		error = lf_clearlock(lock);
125		FREE(lock, M_LOCKF);
126		return (error);
127
128	case F_GETLK:
129		error = lf_getlock(lock, fl);
130		FREE(lock, M_LOCKF);
131		return (error);
132
133	default:
134		free(lock, M_LOCKF);
135		return (EINVAL);
136	}
137	/* NOTREACHED */
138}
139
140/*
141 * This variable controls the maximum number of processes that will
142 * be checked in doing deadlock detection.
143 */
144int maxlockdepth = MAXDEPTH;
145
146#ifdef LOCKF_DEBUG
147int	lockf_debug = 0;
148#endif /* LOCKF_DEBUG */
149
150#define NOLOCKF (struct lockf *)0
151#define SELF	0x1
152#define OTHERS	0x2
153
154/*
155 * Set a byte-range lock.
156 */
157lf_setlock(lock)
158	register struct lockf *lock;
159{
160	register struct lockf *block;
161	struct lockf **head = lock->lf_head;
162	struct lockf **prev, *overlap, *ltmp;
163	static char lockstr[] = "lockf";
164	int ovcase, priority, needtolink, error;
165
166#ifdef LOCKF_DEBUG
167	if (lockf_debug & 1)
168		lf_print("lf_setlock", lock);
169#endif /* LOCKF_DEBUG */
170
171	/*
172	 * Set the priority
173	 */
174	priority = PLOCK;
175	if (lock->lf_type == F_WRLCK)
176		priority += 4;
177	priority |= PCATCH;
178	/*
179	 * Scan lock list for this file looking for locks that would block us.
180	 */
181	while (block = lf_getblock(lock)) {
182		/*
183		 * Free the structure and return if nonblocking.
184		 */
185		if ((lock->lf_flags & F_WAIT) == 0) {
186			FREE(lock, M_LOCKF);
187			return (EAGAIN);
188		}
189		/*
190		 * We are blocked. Since flock style locks cover
191		 * the whole file, there is no chance for deadlock.
192		 * For byte-range locks we must check for deadlock.
193		 *
194		 * Deadlock detection is done by looking through the
195		 * wait channels to see if there are any cycles that
196		 * involve us. MAXDEPTH is set just to make sure we
197		 * do not go off into neverland.
198		 */
199		if ((lock->lf_flags & F_POSIX) &&
200		    (block->lf_flags & F_POSIX)) {
201			register struct proc *wproc;
202			register struct lockf *waitblock;
203			int i = 0;
204
205			/* The block is waiting on something */
206			wproc = (struct proc *)block->lf_id;
207			while (wproc->p_wchan &&
208			       (wproc->p_wmesg == lockstr) &&
209			       (i++ < maxlockdepth)) {
210				waitblock = (struct lockf *)wproc->p_wchan;
211				/* Get the owner of the blocking lock */
212				waitblock = waitblock->lf_next;
213				if ((waitblock->lf_flags & F_POSIX) == 0)
214					break;
215				wproc = (struct proc *)waitblock->lf_id;
216				if (wproc == (struct proc *)lock->lf_id) {
217					free(lock, M_LOCKF);
218					return (EDEADLK);
219				}
220			}
221		}
222		/*
223		 * For flock type locks, we must first remove
224		 * any shared locks that we hold before we sleep
225		 * waiting for an exclusive lock.
226		 */
227		if ((lock->lf_flags & F_FLOCK) &&
228		    lock->lf_type == F_WRLCK) {
229			lock->lf_type = F_UNLCK;
230			(void) lf_clearlock(lock);
231			lock->lf_type = F_WRLCK;
232		}
233		/*
234		 * Add our lock to the blocked list and sleep until we're free.
235		 * Remember who blocked us (for deadlock detection).
236		 */
237		lock->lf_next = block;
238		lf_addblock(block, lock);
239#ifdef LOCKF_DEBUG
240		if (lockf_debug & 1) {
241			lf_print("lf_setlock: blocking on", block);
242			lf_printlist("lf_setlock", block);
243		}
244#endif /* LOCKF_DEBUG */
245	if (error = tsleep((caddr_t)lock, priority, lockstr, 0)) {
246			/*
247			 * Delete ourselves from the waiting to lock list.
248			 */
249			for (block = lock->lf_next;
250			     block != NOLOCKF;
251			     block = block->lf_block) {
252				if (block->lf_block != lock)
253					continue;
254				block->lf_block = block->lf_block->lf_block;
255				free(lock, M_LOCKF);
256				return (error);
257			}
258			panic("lf_setlock: lost lock");
259		}
260	}
261	/*
262	 * No blocks!!  Add the lock.  Note that we will
263	 * downgrade or upgrade any overlapping locks this
264	 * process already owns.
265	 *
266	 * Skip over locks owned by other processes.
267	 * Handle any locks that overlap and are owned by ourselves.
268	 */
269	prev = head;
270	block = *head;
271	needtolink = 1;
272	for (;;) {
273		if (ovcase = lf_findoverlap(block, lock, SELF, &prev, &overlap))
274			block = overlap->lf_next;
275		/*
276		 * Six cases:
277		 *	0) no overlap
278		 *	1) overlap == lock
279		 *	2) overlap contains lock
280		 *	3) lock contains overlap
281		 *	4) overlap starts before lock
282		 *	5) overlap ends after lock
283		 */
284		switch (ovcase) {
285		case 0: /* no overlap */
286			if (needtolink) {
287				*prev = lock;
288				lock->lf_next = overlap;
289			}
290			break;
291
292		case 1: /* overlap == lock */
293			/*
294			 * If downgrading lock, others may be
295			 * able to acquire it.
296			 */
297			if (lock->lf_type == F_RDLCK &&
298			    overlap->lf_type == F_WRLCK)
299				lf_wakelock(overlap);
300			overlap->lf_type = lock->lf_type;
301			FREE(lock, M_LOCKF);
302			lock = overlap; /* for debug output below */
303			break;
304
305		case 2: /* overlap contains lock */
306			/*
307			 * Check for common starting point and different types.
308			 */
309			if (overlap->lf_type == lock->lf_type) {
310				free(lock, M_LOCKF);
311				lock = overlap; /* for debug output below */
312				break;
313			}
314			if (overlap->lf_start == lock->lf_start) {
315				*prev = lock;
316				lock->lf_next = overlap;
317				overlap->lf_start = lock->lf_end + 1;
318			} else
319				lf_split(overlap, lock);
320			lf_wakelock(overlap);
321			break;
322
323		case 3: /* lock contains overlap */
324			/*
325			 * If downgrading lock, others may be able to
326			 * acquire it, otherwise take the list.
327			 */
328			if (lock->lf_type == F_RDLCK &&
329			    overlap->lf_type == F_WRLCK) {
330				lf_wakelock(overlap);
331			} else {
332				ltmp = lock->lf_block;
333				lock->lf_block = overlap->lf_block;
334				lf_addblock(lock, ltmp);
335			}
336			/*
337			 * Add the new lock if necessary and delete the overlap.
338			 */
339			if (needtolink) {
340				*prev = lock;
341				lock->lf_next = overlap->lf_next;
342				prev = &lock->lf_next;
343				needtolink = 0;
344			} else
345				*prev = overlap->lf_next;
346			free(overlap, M_LOCKF);
347			continue;
348
349		case 4: /* overlap starts before lock */
350			/*
351			 * Add lock after overlap on the list.
352			 */
353			lock->lf_next = overlap->lf_next;
354			overlap->lf_next = lock;
355			overlap->lf_end = lock->lf_start - 1;
356			prev = &lock->lf_next;
357			lf_wakelock(overlap);
358			needtolink = 0;
359			continue;
360
361		case 5: /* overlap ends after lock */
362			/*
363			 * Add the new lock before overlap.
364			 */
365			if (needtolink) {
366				*prev = lock;
367				lock->lf_next = overlap;
368			}
369			overlap->lf_start = lock->lf_end + 1;
370			lf_wakelock(overlap);
371			break;
372		}
373		break;
374	}
375#ifdef LOCKF_DEBUG
376	if (lockf_debug & 1) {
377		lf_print("lf_setlock: got the lock", lock);
378		lf_printlist("lf_setlock", lock);
379	}
380#endif /* LOCKF_DEBUG */
381	return (0);
382}
383
384/*
385 * Remove a byte-range lock on an inode.
386 *
387 * Generally, find the lock (or an overlap to that lock)
388 * and remove it (or shrink it), then wakeup anyone we can.
389 */
390lf_clearlock(unlock)
391	register struct lockf *unlock;
392{
393	struct lockf **head = unlock->lf_head;
394	register struct lockf *lf = *head;
395	struct lockf *overlap, **prev;
396	int ovcase;
397
398	if (lf == NOLOCKF)
399		return (0);
400#ifdef LOCKF_DEBUG
401	if (unlock->lf_type != F_UNLCK)
402		panic("lf_clearlock: bad type");
403	if (lockf_debug & 1)
404		lf_print("lf_clearlock", unlock);
405#endif /* LOCKF_DEBUG */
406	prev = head;
407	while (ovcase = lf_findoverlap(lf, unlock, SELF, &prev, &overlap)) {
408		/*
409		 * Wakeup the list of locks to be retried.
410		 */
411		lf_wakelock(overlap);
412
413		switch (ovcase) {
414
415		case 1: /* overlap == lock */
416			*prev = overlap->lf_next;
417			FREE(overlap, M_LOCKF);
418			break;
419
420		case 2: /* overlap contains lock: split it */
421			if (overlap->lf_start == unlock->lf_start) {
422				overlap->lf_start = unlock->lf_end + 1;
423				break;
424			}
425			lf_split(overlap, unlock);
426			overlap->lf_next = unlock->lf_next;
427			break;
428
429		case 3: /* lock contains overlap */
430			*prev = overlap->lf_next;
431			lf = overlap->lf_next;
432			free(overlap, M_LOCKF);
433			continue;
434
435		case 4: /* overlap starts before lock */
436			overlap->lf_end = unlock->lf_start - 1;
437			prev = &overlap->lf_next;
438			lf = overlap->lf_next;
439			continue;
440
441		case 5: /* overlap ends after lock */
442			overlap->lf_start = unlock->lf_end + 1;
443			break;
444		}
445		break;
446	}
447#ifdef LOCKF_DEBUG
448	if (lockf_debug & 1)
449		lf_printlist("lf_clearlock", unlock);
450#endif /* LOCKF_DEBUG */
451	return (0);
452}
453
454/*
455 * Check whether there is a blocking lock,
456 * and if so return its process identifier.
457 */
458lf_getlock(lock, fl)
459	register struct lockf *lock;
460	register struct flock *fl;
461{
462	register struct lockf *block;
463	off_t start, end;
464
465#ifdef LOCKF_DEBUG
466	if (lockf_debug & 1)
467		lf_print("lf_getlock", lock);
468#endif /* LOCKF_DEBUG */
469
470	if (block = lf_getblock(lock)) {
471		fl->l_type = block->lf_type;
472		fl->l_whence = SEEK_SET;
473		fl->l_start = block->lf_start;
474		if (block->lf_end == -1)
475			fl->l_len = 0;
476		else
477			fl->l_len = block->lf_end - block->lf_start + 1;
478		if (block->lf_flags & F_POSIX)
479			fl->l_pid = ((struct proc *)(block->lf_id))->p_pid;
480		else
481			fl->l_pid = -1;
482	} else {
483		fl->l_type = F_UNLCK;
484	}
485	return (0);
486}
487
488/*
489 * Walk the list of locks for an inode and
490 * return the first blocking lock.
491 */
492struct lockf *
493lf_getblock(lock)
494	register struct lockf *lock;
495{
496	struct lockf **prev, *overlap, *lf = *(lock->lf_head);
497	int ovcase;
498
499	prev = lock->lf_head;
500	while (ovcase = lf_findoverlap(lf, lock, OTHERS, &prev, &overlap)) {
501		/*
502		 * We've found an overlap, see if it blocks us
503		 */
504		if ((lock->lf_type == F_WRLCK || overlap->lf_type == F_WRLCK))
505			return (overlap);
506		/*
507		 * Nope, point to the next one on the list and
508		 * see if it blocks us
509		 */
510		lf = overlap->lf_next;
511	}
512	return (NOLOCKF);
513}
514
515/*
516 * Walk the list of locks for an inode to
517 * find an overlapping lock (if any).
518 *
519 * NOTE: this returns only the FIRST overlapping lock.  There
520 *	 may be more than one.
521 */
522lf_findoverlap(lf, lock, type, prev, overlap)
523	register struct lockf *lf;
524	struct lockf *lock;
525	int type;
526	struct lockf ***prev;
527	struct lockf **overlap;
528{
529	off_t start, end;
530
531	*overlap = lf;
532	if (lf == NOLOCKF)
533		return (0);
534#ifdef LOCKF_DEBUG
535	if (lockf_debug & 2)
536		lf_print("lf_findoverlap: looking for overlap in", lock);
537#endif /* LOCKF_DEBUG */
538	start = lock->lf_start;
539	end = lock->lf_end;
540	while (lf != NOLOCKF) {
541		if (((type & SELF) && lf->lf_id != lock->lf_id) ||
542		    ((type & OTHERS) && lf->lf_id == lock->lf_id)) {
543			*prev = &lf->lf_next;
544			*overlap = lf = lf->lf_next;
545			continue;
546		}
547#ifdef LOCKF_DEBUG
548		if (lockf_debug & 2)
549			lf_print("\tchecking", lf);
550#endif /* LOCKF_DEBUG */
551		/*
552		 * OK, check for overlap
553		 *
554		 * Six cases:
555		 *	0) no overlap
556		 *	1) overlap == lock
557		 *	2) overlap contains lock
558		 *	3) lock contains overlap
559		 *	4) overlap starts before lock
560		 *	5) overlap ends after lock
561		 */
562		if ((lf->lf_end != -1 && start > lf->lf_end) ||
563		    (end != -1 && lf->lf_start > end)) {
564			/* Case 0 */
565#ifdef LOCKF_DEBUG
566			if (lockf_debug & 2)
567				printf("no overlap\n");
568#endif /* LOCKF_DEBUG */
569			if ((type & SELF) && end != -1 && lf->lf_start > end)
570				return (0);
571			*prev = &lf->lf_next;
572			*overlap = lf = lf->lf_next;
573			continue;
574		}
575		if ((lf->lf_start == start) && (lf->lf_end == end)) {
576			/* Case 1 */
577#ifdef LOCKF_DEBUG
578			if (lockf_debug & 2)
579				printf("overlap == lock\n");
580#endif /* LOCKF_DEBUG */
581			return (1);
582		}
583		if ((lf->lf_start <= start) &&
584		    (end != -1) &&
585		    ((lf->lf_end >= end) || (lf->lf_end == -1))) {
586			/* Case 2 */
587#ifdef LOCKF_DEBUG
588			if (lockf_debug & 2)
589				printf("overlap contains lock\n");
590#endif /* LOCKF_DEBUG */
591			return (2);
592		}
593		if (start <= lf->lf_start &&
594			   (end == -1 ||
595			   (lf->lf_end != -1 && end >= lf->lf_end))) {
596			/* Case 3 */
597#ifdef LOCKF_DEBUG
598			if (lockf_debug & 2)
599				printf("lock contains overlap\n");
600#endif /* LOCKF_DEBUG */
601			return (3);
602		}
603		if ((lf->lf_start < start) &&
604			((lf->lf_end >= start) || (lf->lf_end == -1))) {
605			/* Case 4 */
606#ifdef LOCKF_DEBUG
607			if (lockf_debug & 2)
608				printf("overlap starts before lock\n");
609#endif /* LOCKF_DEBUG */
610			return (4);
611		}
612		if ((lf->lf_start > start) &&
613			(end != -1) &&
614			((lf->lf_end > end) || (lf->lf_end == -1))) {
615			/* Case 5 */
616#ifdef LOCKF_DEBUG
617			if (lockf_debug & 2)
618				printf("overlap ends after lock\n");
619#endif /* LOCKF_DEBUG */
620			return (5);
621		}
622		panic("lf_findoverlap: default");
623	}
624	return (0);
625}
626
627/*
628 * Add a lock to the end of the blocked list.
629 */
630lf_addblock(lock, blocked)
631	struct lockf *lock;
632	struct lockf *blocked;
633{
634	register struct lockf *lf;
635
636	if (blocked == NOLOCKF)
637		return;
638#ifdef LOCKF_DEBUG
639	if (lockf_debug & 2) {
640		lf_print("addblock: adding", blocked);
641		lf_print("to blocked list of", lock);
642	}
643#endif /* LOCKF_DEBUG */
644	if ((lf = lock->lf_block) == NOLOCKF) {
645		lock->lf_block = blocked;
646		return;
647	}
648	while (lf->lf_block != NOLOCKF)
649		lf = lf->lf_block;
650	lf->lf_block = blocked;
651	return;
652}
653
654/*
655 * Split a lock and a contained region into
656 * two or three locks as necessary.
657 */
658lf_split(lock1, lock2)
659	register struct lockf *lock1;
660	register struct lockf *lock2;
661{
662	register struct lockf *splitlock;
663
664#ifdef LOCKF_DEBUG
665	if (lockf_debug & 2) {
666		lf_print("lf_split", lock1);
667		lf_print("splitting from", lock2);
668	}
669#endif /* LOCKF_DEBUG */
670	/*
671	 * Check to see if spliting into only two pieces.
672	 */
673	if (lock1->lf_start == lock2->lf_start) {
674		lock1->lf_start = lock2->lf_end + 1;
675		lock2->lf_next = lock1;
676		return;
677	}
678	if (lock1->lf_end == lock2->lf_end) {
679		lock1->lf_end = lock2->lf_start - 1;
680		lock2->lf_next = lock1->lf_next;
681		lock1->lf_next = lock2;
682		return;
683	}
684	/*
685	 * Make a new lock consisting of the last part of
686	 * the encompassing lock
687	 */
688	MALLOC(splitlock, struct lockf *, sizeof *splitlock, M_LOCKF, M_WAITOK);
689	bcopy((caddr_t)lock1, (caddr_t)splitlock, sizeof *splitlock);
690	splitlock->lf_start = lock2->lf_end + 1;
691	splitlock->lf_block = NOLOCKF;
692	lock1->lf_end = lock2->lf_start - 1;
693	/*
694	 * OK, now link it in
695	 */
696	splitlock->lf_next = lock1->lf_next;
697	lock2->lf_next = splitlock;
698	lock1->lf_next = lock2;
699}
700
701/*
702 * Wakeup a blocklist
703 */
704lf_wakelock(listhead)
705	struct lockf *listhead;
706{
707	register struct lockf *blocklist, *wakelock;
708
709	blocklist = listhead->lf_block;
710	listhead->lf_block = NOLOCKF;
711	while (blocklist != NOLOCKF) {
712		wakelock = blocklist;
713		blocklist = blocklist->lf_block;
714		wakelock->lf_block = NOLOCKF;
715		wakelock->lf_next = NOLOCKF;
716#ifdef LOCKF_DEBUG
717		if (lockf_debug & 2)
718			lf_print("lf_wakelock: awakening", wakelock);
719#endif /* LOCKF_DEBUG */
720		wakeup((caddr_t)wakelock);
721	}
722}
723
724#ifdef LOCKF_DEBUG
725/*
726 * Print out a lock.
727 */
728lf_print(tag, lock)
729	char *tag;
730	register struct lockf *lock;
731{
732
733	printf("%s: lock 0x%lx for ", tag, lock);
734	if (lock->lf_flags & F_POSIX)
735		printf("proc %d", ((struct proc *)(lock->lf_id))->p_pid);
736	else
737		printf("id 0x%x", lock->lf_id);
738	printf(" in ino %d on dev <%d, %d>, %s, start %d, end %d",
739		lock->lf_inode->i_number,
740		major(lock->lf_inode->i_dev),
741		minor(lock->lf_inode->i_dev),
742		lock->lf_type == F_RDLCK ? "shared" :
743		lock->lf_type == F_WRLCK ? "exclusive" :
744		lock->lf_type == F_UNLCK ? "unlock" :
745		"unknown", lock->lf_start, lock->lf_end);
746	if (lock->lf_block)
747		printf(" block 0x%x\n", lock->lf_block);
748	else
749		printf("\n");
750}
751
752lf_printlist(tag, lock)
753	char *tag;
754	struct lockf *lock;
755{
756	register struct lockf *lf;
757
758	printf("%s: Lock list for ino %d on dev <%d, %d>:\n",
759		tag, lock->lf_inode->i_number,
760		major(lock->lf_inode->i_dev),
761		minor(lock->lf_inode->i_dev));
762	for (lf = lock->lf_inode->i_lockf; lf; lf = lf->lf_next) {
763		printf("\tlock 0x%lx for ", lf);
764		if (lf->lf_flags & F_POSIX)
765			printf("proc %d", ((struct proc *)(lf->lf_id))->p_pid);
766		else
767			printf("id 0x%x", lf->lf_id);
768		printf(", %s, start %d, end %d",
769			lf->lf_type == F_RDLCK ? "shared" :
770			lf->lf_type == F_WRLCK ? "exclusive" :
771			lf->lf_type == F_UNLCK ? "unlock" :
772			"unknown", lf->lf_start, lf->lf_end);
773		if (lf->lf_block)
774			printf(" block 0x%x\n", lf->lf_block);
775		else
776			printf("\n");
777	}
778}
779#endif /* LOCKF_DEBUG */
780