xref: /linux/fs/dlm/debug_fs.c (revision 7ec7fb394298c212c30e063c57e0aa895efe9439)
1 /******************************************************************************
2 *******************************************************************************
3 **
4 **  Copyright (C) 2005-2008 Red Hat, Inc.  All rights reserved.
5 **
6 **  This copyrighted material is made available to anyone wishing to use,
7 **  modify, copy, or redistribute it subject to the terms and conditions
8 **  of the GNU General Public License v.2.
9 **
10 *******************************************************************************
11 ******************************************************************************/
12 
13 #include <linux/pagemap.h>
14 #include <linux/seq_file.h>
15 #include <linux/module.h>
16 #include <linux/ctype.h>
17 #include <linux/debugfs.h>
18 
19 #include "dlm_internal.h"
20 #include "lock.h"
21 
22 #define DLM_DEBUG_BUF_LEN 4096
23 static char debug_buf[DLM_DEBUG_BUF_LEN];
24 static struct mutex debug_buf_lock;
25 
26 static struct dentry *dlm_root;
27 
28 struct rsb_iter {
29 	int entry;
30 	int format;
31 	int header;
32 	struct dlm_ls *ls;
33 	struct list_head *next;
34 	struct dlm_rsb *rsb;
35 };
36 
37 /*
38  * dump all rsb's in the lockspace hash table
39  */
40 
41 static char *print_lockmode(int mode)
42 {
43 	switch (mode) {
44 	case DLM_LOCK_IV:
45 		return "--";
46 	case DLM_LOCK_NL:
47 		return "NL";
48 	case DLM_LOCK_CR:
49 		return "CR";
50 	case DLM_LOCK_CW:
51 		return "CW";
52 	case DLM_LOCK_PR:
53 		return "PR";
54 	case DLM_LOCK_PW:
55 		return "PW";
56 	case DLM_LOCK_EX:
57 		return "EX";
58 	default:
59 		return "??";
60 	}
61 }
62 
63 static void print_format1_lock(struct seq_file *s, struct dlm_lkb *lkb,
64 			       struct dlm_rsb *res)
65 {
66 	seq_printf(s, "%08x %s", lkb->lkb_id, print_lockmode(lkb->lkb_grmode));
67 
68 	if (lkb->lkb_status == DLM_LKSTS_CONVERT
69 	    || lkb->lkb_status == DLM_LKSTS_WAITING)
70 		seq_printf(s, " (%s)", print_lockmode(lkb->lkb_rqmode));
71 
72 	if (lkb->lkb_nodeid) {
73 		if (lkb->lkb_nodeid != res->res_nodeid)
74 			seq_printf(s, " Remote: %3d %08x", lkb->lkb_nodeid,
75 				   lkb->lkb_remid);
76 		else
77 			seq_printf(s, " Master:     %08x", lkb->lkb_remid);
78 	}
79 
80 	if (lkb->lkb_wait_type)
81 		seq_printf(s, " wait_type: %d", lkb->lkb_wait_type);
82 
83 	seq_printf(s, "\n");
84 }
85 
86 static int print_format1(struct dlm_rsb *res, struct seq_file *s)
87 {
88 	struct dlm_lkb *lkb;
89 	int i, lvblen = res->res_ls->ls_lvblen, recover_list, root_list;
90 
91 	lock_rsb(res);
92 
93 	seq_printf(s, "\nResource %p Name (len=%d) \"", res, res->res_length);
94 	for (i = 0; i < res->res_length; i++) {
95 		if (isprint(res->res_name[i]))
96 			seq_printf(s, "%c", res->res_name[i]);
97 		else
98 			seq_printf(s, "%c", '.');
99 	}
100 	if (res->res_nodeid > 0)
101 		seq_printf(s, "\"  \nLocal Copy, Master is node %d\n",
102 			   res->res_nodeid);
103 	else if (res->res_nodeid == 0)
104 		seq_printf(s, "\"  \nMaster Copy\n");
105 	else if (res->res_nodeid == -1)
106 		seq_printf(s, "\"  \nLooking up master (lkid %x)\n",
107 			   res->res_first_lkid);
108 	else
109 		seq_printf(s, "\"  \nInvalid master %d\n", res->res_nodeid);
110 
111 	/* Print the LVB: */
112 	if (res->res_lvbptr) {
113 		seq_printf(s, "LVB: ");
114 		for (i = 0; i < lvblen; i++) {
115 			if (i == lvblen / 2)
116 				seq_printf(s, "\n     ");
117 			seq_printf(s, "%02x ",
118 				   (unsigned char) res->res_lvbptr[i]);
119 		}
120 		if (rsb_flag(res, RSB_VALNOTVALID))
121 			seq_printf(s, " (INVALID)");
122 		seq_printf(s, "\n");
123 	}
124 
125 	root_list = !list_empty(&res->res_root_list);
126 	recover_list = !list_empty(&res->res_recover_list);
127 
128 	if (root_list || recover_list) {
129 		seq_printf(s, "Recovery: root %d recover %d flags %lx "
130 			   "count %d\n", root_list, recover_list,
131 			   res->res_flags, res->res_recover_locks_count);
132 	}
133 
134 	/* Print the locks attached to this resource */
135 	seq_printf(s, "Granted Queue\n");
136 	list_for_each_entry(lkb, &res->res_grantqueue, lkb_statequeue)
137 		print_format1_lock(s, lkb, res);
138 
139 	seq_printf(s, "Conversion Queue\n");
140 	list_for_each_entry(lkb, &res->res_convertqueue, lkb_statequeue)
141 		print_format1_lock(s, lkb, res);
142 
143 	seq_printf(s, "Waiting Queue\n");
144 	list_for_each_entry(lkb, &res->res_waitqueue, lkb_statequeue)
145 		print_format1_lock(s, lkb, res);
146 
147 	if (list_empty(&res->res_lookup))
148 		goto out;
149 
150 	seq_printf(s, "Lookup Queue\n");
151 	list_for_each_entry(lkb, &res->res_lookup, lkb_rsb_lookup) {
152 		seq_printf(s, "%08x %s", lkb->lkb_id,
153 			   print_lockmode(lkb->lkb_rqmode));
154 		if (lkb->lkb_wait_type)
155 			seq_printf(s, " wait_type: %d", lkb->lkb_wait_type);
156 		seq_printf(s, "\n");
157 	}
158  out:
159 	unlock_rsb(res);
160 	return 0;
161 }
162 
163 static void print_format2_lock(struct seq_file *s, struct dlm_lkb *lkb,
164 			       struct dlm_rsb *r)
165 {
166 	u64 xid = 0;
167 	u64 us;
168 
169 	if (lkb->lkb_flags & DLM_IFL_USER) {
170 		if (lkb->lkb_ua)
171 			xid = lkb->lkb_ua->xid;
172 	}
173 
174 	/* microseconds since lkb was added to current queue */
175 	us = ktime_to_us(ktime_sub(ktime_get(), lkb->lkb_timestamp));
176 
177 	/* id nodeid remid pid xid exflags flags sts grmode rqmode time_us
178 	   r_nodeid r_len r_name */
179 
180 	seq_printf(s, "%x %d %x %u %llu %x %x %d %d %d %llu %u %d \"%s\"\n",
181 		   lkb->lkb_id,
182 		   lkb->lkb_nodeid,
183 		   lkb->lkb_remid,
184 		   lkb->lkb_ownpid,
185 		   (unsigned long long)xid,
186 		   lkb->lkb_exflags,
187 		   lkb->lkb_flags,
188 		   lkb->lkb_status,
189 		   lkb->lkb_grmode,
190 		   lkb->lkb_rqmode,
191 		   (unsigned long long)us,
192 		   r->res_nodeid,
193 		   r->res_length,
194 		   r->res_name);
195 }
196 
197 static int print_format2(struct dlm_rsb *r, struct seq_file *s)
198 {
199 	struct dlm_lkb *lkb;
200 
201 	lock_rsb(r);
202 
203 	list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue)
204 		print_format2_lock(s, lkb, r);
205 
206 	list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue)
207 		print_format2_lock(s, lkb, r);
208 
209 	list_for_each_entry(lkb, &r->res_waitqueue, lkb_statequeue)
210 		print_format2_lock(s, lkb, r);
211 
212 	unlock_rsb(r);
213 	return 0;
214 }
215 
216 static void print_format3_lock(struct seq_file *s, struct dlm_lkb *lkb,
217 			       int rsb_lookup)
218 {
219 	u64 xid = 0;
220 
221 	if (lkb->lkb_flags & DLM_IFL_USER) {
222 		if (lkb->lkb_ua)
223 			xid = lkb->lkb_ua->xid;
224 	}
225 
226 	seq_printf(s, "lkb %x %d %x %u %llu %x %x %d %d %d %d %d %d %u %llu %llu\n",
227 		   lkb->lkb_id,
228 		   lkb->lkb_nodeid,
229 		   lkb->lkb_remid,
230 		   lkb->lkb_ownpid,
231 		   (unsigned long long)xid,
232 		   lkb->lkb_exflags,
233 		   lkb->lkb_flags,
234 		   lkb->lkb_status,
235 		   lkb->lkb_grmode,
236 		   lkb->lkb_rqmode,
237 		   lkb->lkb_highbast,
238 		   rsb_lookup,
239 		   lkb->lkb_wait_type,
240 		   lkb->lkb_lvbseq,
241 		   (unsigned long long)ktime_to_ns(lkb->lkb_timestamp),
242 		   (unsigned long long)ktime_to_ns(lkb->lkb_time_bast));
243 }
244 
245 static int print_format3(struct dlm_rsb *r, struct seq_file *s)
246 {
247 	struct dlm_lkb *lkb;
248 	int i, lvblen = r->res_ls->ls_lvblen;
249 	int print_name = 1;
250 
251 	lock_rsb(r);
252 
253 	seq_printf(s, "rsb %p %d %x %lx %d %d %u %d ",
254 		   r,
255 		   r->res_nodeid,
256 		   r->res_first_lkid,
257 		   r->res_flags,
258 		   !list_empty(&r->res_root_list),
259 		   !list_empty(&r->res_recover_list),
260 		   r->res_recover_locks_count,
261 		   r->res_length);
262 
263 	for (i = 0; i < r->res_length; i++) {
264 		if (!isascii(r->res_name[i]) || !isprint(r->res_name[i]))
265 			print_name = 0;
266 	}
267 
268 	seq_printf(s, "%s", print_name ? "str " : "hex");
269 
270 	for (i = 0; i < r->res_length; i++) {
271 		if (print_name)
272 			seq_printf(s, "%c", r->res_name[i]);
273 		else
274 			seq_printf(s, " %02x", (unsigned char)r->res_name[i]);
275 	}
276 	seq_printf(s, "\n");
277 
278 	if (!r->res_lvbptr)
279 		goto do_locks;
280 
281 	seq_printf(s, "lvb %u %d", r->res_lvbseq, lvblen);
282 
283 	for (i = 0; i < lvblen; i++)
284 		seq_printf(s, " %02x", (unsigned char)r->res_lvbptr[i]);
285 	seq_printf(s, "\n");
286 
287  do_locks:
288 	list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue)
289 		print_format3_lock(s, lkb, 0);
290 
291 	list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue)
292 		print_format3_lock(s, lkb, 0);
293 
294 	list_for_each_entry(lkb, &r->res_waitqueue, lkb_statequeue)
295 		print_format3_lock(s, lkb, 0);
296 
297 	list_for_each_entry(lkb, &r->res_lookup, lkb_rsb_lookup)
298 		print_format3_lock(s, lkb, 1);
299 
300 	unlock_rsb(r);
301 	return 0;
302 }
303 
304 static int rsb_iter_next(struct rsb_iter *ri)
305 {
306 	struct dlm_ls *ls = ri->ls;
307 	int i;
308 
309 	if (!ri->next) {
310  top:
311 		/* Find the next non-empty hash bucket */
312 		for (i = ri->entry; i < ls->ls_rsbtbl_size; i++) {
313 			read_lock(&ls->ls_rsbtbl[i].lock);
314 			if (!list_empty(&ls->ls_rsbtbl[i].list)) {
315 				ri->next = ls->ls_rsbtbl[i].list.next;
316 				ri->rsb = list_entry(ri->next, struct dlm_rsb,
317 							res_hashchain);
318 				dlm_hold_rsb(ri->rsb);
319 				read_unlock(&ls->ls_rsbtbl[i].lock);
320 				break;
321 			}
322 			read_unlock(&ls->ls_rsbtbl[i].lock);
323 		}
324 		ri->entry = i;
325 
326 		if (ri->entry >= ls->ls_rsbtbl_size)
327 			return 1;
328 	} else {
329 		struct dlm_rsb *old = ri->rsb;
330 		i = ri->entry;
331 		read_lock(&ls->ls_rsbtbl[i].lock);
332 		ri->next = ri->next->next;
333 		if (ri->next->next == ls->ls_rsbtbl[i].list.next) {
334 			/* End of list - move to next bucket */
335 			ri->next = NULL;
336 			ri->entry++;
337 			read_unlock(&ls->ls_rsbtbl[i].lock);
338 			dlm_put_rsb(old);
339 			goto top;
340 		}
341 		ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
342 		dlm_hold_rsb(ri->rsb);
343 		read_unlock(&ls->ls_rsbtbl[i].lock);
344 		dlm_put_rsb(old);
345 	}
346 
347 	return 0;
348 }
349 
350 static void rsb_iter_free(struct rsb_iter *ri)
351 {
352 	kfree(ri);
353 }
354 
355 static struct rsb_iter *rsb_iter_init(struct dlm_ls *ls)
356 {
357 	struct rsb_iter *ri;
358 
359 	ri = kzalloc(sizeof *ri, GFP_KERNEL);
360 	if (!ri)
361 		return NULL;
362 
363 	ri->ls = ls;
364 	ri->entry = 0;
365 	ri->next = NULL;
366 	ri->format = 1;
367 
368 	if (rsb_iter_next(ri)) {
369 		rsb_iter_free(ri);
370 		return NULL;
371 	}
372 
373 	return ri;
374 }
375 
376 static void *rsb_seq_start(struct seq_file *file, loff_t *pos)
377 {
378 	struct rsb_iter *ri;
379 	loff_t n = *pos;
380 
381 	ri = rsb_iter_init(file->private);
382 	if (!ri)
383 		return NULL;
384 
385 	while (n--) {
386 		if (rsb_iter_next(ri)) {
387 			rsb_iter_free(ri);
388 			return NULL;
389 		}
390 	}
391 
392 	return ri;
393 }
394 
395 static void *rsb_seq_next(struct seq_file *file, void *iter_ptr, loff_t *pos)
396 {
397 	struct rsb_iter *ri = iter_ptr;
398 
399 	(*pos)++;
400 
401 	if (rsb_iter_next(ri)) {
402 		rsb_iter_free(ri);
403 		return NULL;
404 	}
405 
406 	return ri;
407 }
408 
409 static void rsb_seq_stop(struct seq_file *file, void *iter_ptr)
410 {
411 	/* nothing for now */
412 }
413 
414 static int rsb_seq_show(struct seq_file *file, void *iter_ptr)
415 {
416 	struct rsb_iter *ri = iter_ptr;
417 
418 	switch (ri->format) {
419 	case 1:
420 		print_format1(ri->rsb, file);
421 		break;
422 	case 2:
423 		if (ri->header) {
424 			seq_printf(file, "id nodeid remid pid xid exflags "
425 					 "flags sts grmode rqmode time_ms "
426 					 "r_nodeid r_len r_name\n");
427 			ri->header = 0;
428 		}
429 		print_format2(ri->rsb, file);
430 		break;
431 	case 3:
432 		if (ri->header) {
433 			seq_printf(file, "version rsb 1.1 lvb 1.1 lkb 1.1\n");
434 			ri->header = 0;
435 		}
436 		print_format3(ri->rsb, file);
437 		break;
438 	}
439 
440 	return 0;
441 }
442 
443 static struct seq_operations rsb_seq_ops = {
444 	.start = rsb_seq_start,
445 	.next  = rsb_seq_next,
446 	.stop  = rsb_seq_stop,
447 	.show  = rsb_seq_show,
448 };
449 
450 static int rsb_open(struct inode *inode, struct file *file)
451 {
452 	struct seq_file *seq;
453 	int ret;
454 
455 	ret = seq_open(file, &rsb_seq_ops);
456 	if (ret)
457 		return ret;
458 
459 	seq = file->private_data;
460 	seq->private = inode->i_private;
461 
462 	return 0;
463 }
464 
465 static const struct file_operations rsb_fops = {
466 	.owner   = THIS_MODULE,
467 	.open    = rsb_open,
468 	.read    = seq_read,
469 	.llseek  = seq_lseek,
470 	.release = seq_release
471 };
472 
473 /*
474  * Dump state in compact per-lock listing
475  */
476 
477 static struct rsb_iter *locks_iter_init(struct dlm_ls *ls, loff_t *pos)
478 {
479 	struct rsb_iter *ri;
480 
481 	ri = kzalloc(sizeof *ri, GFP_KERNEL);
482 	if (!ri)
483 		return NULL;
484 
485 	ri->ls = ls;
486 	ri->entry = 0;
487 	ri->next = NULL;
488 	ri->format = 2;
489 
490 	if (*pos == 0)
491 		ri->header = 1;
492 
493 	if (rsb_iter_next(ri)) {
494 		rsb_iter_free(ri);
495 		return NULL;
496 	}
497 
498 	return ri;
499 }
500 
501 static void *locks_seq_start(struct seq_file *file, loff_t *pos)
502 {
503 	struct rsb_iter *ri;
504 	loff_t n = *pos;
505 
506 	ri = locks_iter_init(file->private, pos);
507 	if (!ri)
508 		return NULL;
509 
510 	while (n--) {
511 		if (rsb_iter_next(ri)) {
512 			rsb_iter_free(ri);
513 			return NULL;
514 		}
515 	}
516 
517 	return ri;
518 }
519 
520 static struct seq_operations locks_seq_ops = {
521 	.start = locks_seq_start,
522 	.next  = rsb_seq_next,
523 	.stop  = rsb_seq_stop,
524 	.show  = rsb_seq_show,
525 };
526 
527 static int locks_open(struct inode *inode, struct file *file)
528 {
529 	struct seq_file *seq;
530 	int ret;
531 
532 	ret = seq_open(file, &locks_seq_ops);
533 	if (ret)
534 		return ret;
535 
536 	seq = file->private_data;
537 	seq->private = inode->i_private;
538 
539 	return 0;
540 }
541 
542 static const struct file_operations locks_fops = {
543 	.owner   = THIS_MODULE,
544 	.open    = locks_open,
545 	.read    = seq_read,
546 	.llseek  = seq_lseek,
547 	.release = seq_release
548 };
549 
550 /*
551  * Dump all rsb/lvb/lkb state in compact listing, more complete than _locks
552  * This can replace both formats 1 and 2 eventually.
553  */
554 
555 static struct rsb_iter *all_iter_init(struct dlm_ls *ls, loff_t *pos)
556 {
557 	struct rsb_iter *ri;
558 
559 	ri = kzalloc(sizeof *ri, GFP_KERNEL);
560 	if (!ri)
561 		return NULL;
562 
563 	ri->ls = ls;
564 	ri->entry = 0;
565 	ri->next = NULL;
566 	ri->format = 3;
567 
568 	if (*pos == 0)
569 		ri->header = 1;
570 
571 	if (rsb_iter_next(ri)) {
572 		rsb_iter_free(ri);
573 		return NULL;
574 	}
575 
576 	return ri;
577 }
578 
579 static void *all_seq_start(struct seq_file *file, loff_t *pos)
580 {
581 	struct rsb_iter *ri;
582 	loff_t n = *pos;
583 
584 	ri = all_iter_init(file->private, pos);
585 	if (!ri)
586 		return NULL;
587 
588 	while (n--) {
589 		if (rsb_iter_next(ri)) {
590 			rsb_iter_free(ri);
591 			return NULL;
592 		}
593 	}
594 
595 	return ri;
596 }
597 
598 static struct seq_operations all_seq_ops = {
599 	.start = all_seq_start,
600 	.next  = rsb_seq_next,
601 	.stop  = rsb_seq_stop,
602 	.show  = rsb_seq_show,
603 };
604 
605 static int all_open(struct inode *inode, struct file *file)
606 {
607 	struct seq_file *seq;
608 	int ret;
609 
610 	ret = seq_open(file, &all_seq_ops);
611 	if (ret)
612 		return ret;
613 
614 	seq = file->private_data;
615 	seq->private = inode->i_private;
616 
617 	return 0;
618 }
619 
620 static const struct file_operations all_fops = {
621 	.owner   = THIS_MODULE,
622 	.open    = all_open,
623 	.read    = seq_read,
624 	.llseek  = seq_lseek,
625 	.release = seq_release
626 };
627 
628 /*
629  * dump lkb's on the ls_waiters list
630  */
631 
632 static int waiters_open(struct inode *inode, struct file *file)
633 {
634 	file->private_data = inode->i_private;
635 	return 0;
636 }
637 
638 static ssize_t waiters_read(struct file *file, char __user *userbuf,
639 			    size_t count, loff_t *ppos)
640 {
641 	struct dlm_ls *ls = file->private_data;
642 	struct dlm_lkb *lkb;
643 	size_t len = DLM_DEBUG_BUF_LEN, pos = 0, ret, rv;
644 
645 	mutex_lock(&debug_buf_lock);
646 	mutex_lock(&ls->ls_waiters_mutex);
647 	memset(debug_buf, 0, sizeof(debug_buf));
648 
649 	list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
650 		ret = snprintf(debug_buf + pos, len - pos, "%x %d %d %s\n",
651 			       lkb->lkb_id, lkb->lkb_wait_type,
652 			       lkb->lkb_nodeid, lkb->lkb_resource->res_name);
653 		if (ret >= len - pos)
654 			break;
655 		pos += ret;
656 	}
657 	mutex_unlock(&ls->ls_waiters_mutex);
658 
659 	rv = simple_read_from_buffer(userbuf, count, ppos, debug_buf, pos);
660 	mutex_unlock(&debug_buf_lock);
661 	return rv;
662 }
663 
664 static const struct file_operations waiters_fops = {
665 	.owner   = THIS_MODULE,
666 	.open    = waiters_open,
667 	.read    = waiters_read
668 };
669 
670 void dlm_delete_debug_file(struct dlm_ls *ls)
671 {
672 	if (ls->ls_debug_rsb_dentry)
673 		debugfs_remove(ls->ls_debug_rsb_dentry);
674 	if (ls->ls_debug_waiters_dentry)
675 		debugfs_remove(ls->ls_debug_waiters_dentry);
676 	if (ls->ls_debug_locks_dentry)
677 		debugfs_remove(ls->ls_debug_locks_dentry);
678 	if (ls->ls_debug_all_dentry)
679 		debugfs_remove(ls->ls_debug_all_dentry);
680 }
681 
682 int dlm_create_debug_file(struct dlm_ls *ls)
683 {
684 	char name[DLM_LOCKSPACE_LEN+8];
685 
686 	/* format 1 */
687 
688 	ls->ls_debug_rsb_dentry = debugfs_create_file(ls->ls_name,
689 						      S_IFREG | S_IRUGO,
690 						      dlm_root,
691 						      ls,
692 						      &rsb_fops);
693 	if (!ls->ls_debug_rsb_dentry)
694 		goto fail;
695 
696 	/* format 2 */
697 
698 	memset(name, 0, sizeof(name));
699 	snprintf(name, DLM_LOCKSPACE_LEN+8, "%s_locks", ls->ls_name);
700 
701 	ls->ls_debug_locks_dentry = debugfs_create_file(name,
702 							S_IFREG | S_IRUGO,
703 							dlm_root,
704 							ls,
705 							&locks_fops);
706 	if (!ls->ls_debug_locks_dentry)
707 		goto fail;
708 
709 	/* format 3 */
710 
711 	memset(name, 0, sizeof(name));
712 	snprintf(name, DLM_LOCKSPACE_LEN+8, "%s_all", ls->ls_name);
713 
714 	ls->ls_debug_all_dentry = debugfs_create_file(name,
715 						      S_IFREG | S_IRUGO,
716 						      dlm_root,
717 						      ls,
718 						      &all_fops);
719 	if (!ls->ls_debug_all_dentry)
720 		goto fail;
721 
722 	memset(name, 0, sizeof(name));
723 	snprintf(name, DLM_LOCKSPACE_LEN+8, "%s_waiters", ls->ls_name);
724 
725 	ls->ls_debug_waiters_dentry = debugfs_create_file(name,
726 							  S_IFREG | S_IRUGO,
727 							  dlm_root,
728 							  ls,
729 							  &waiters_fops);
730 	if (!ls->ls_debug_waiters_dentry)
731 		goto fail;
732 
733 	return 0;
734 
735  fail:
736 	dlm_delete_debug_file(ls);
737 	return -ENOMEM;
738 }
739 
740 int __init dlm_register_debugfs(void)
741 {
742 	mutex_init(&debug_buf_lock);
743 	dlm_root = debugfs_create_dir("dlm", NULL);
744 	return dlm_root ? 0 : -ENOMEM;
745 }
746 
747 void dlm_unregister_debugfs(void)
748 {
749 	debugfs_remove(dlm_root);
750 }
751 
752