xref: /freebsd/sys/geom/geom_io.c (revision d056fa046c6a91b90cd98165face0e42a33a5173)
1 /*-
2  * Copyright (c) 2002 Poul-Henning Kamp
3  * Copyright (c) 2002 Networks Associates Technology, Inc.
4  * All rights reserved.
5  *
6  * This software was developed for the FreeBSD Project by Poul-Henning Kamp
7  * and NAI Labs, the Security Research Division of Network Associates, Inc.
8  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
9  * DARPA CHATS research program.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. The names of the authors may not be used to endorse or promote
20  *    products derived from this software without specific prior written
21  *    permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/bio.h>
44 #include <sys/ktr.h>
45 #include <sys/proc.h>
46 #include <sys/stack.h>
47 
48 #include <sys/errno.h>
49 #include <geom/geom.h>
50 #include <geom/geom_int.h>
51 #include <sys/devicestat.h>
52 
53 #include <vm/uma.h>
54 
55 static struct g_bioq g_bio_run_down;
56 static struct g_bioq g_bio_run_up;
57 static struct g_bioq g_bio_run_task;
58 
59 static u_int pace;
60 static uma_zone_t	biozone;
61 
62 #include <machine/atomic.h>
63 
64 static void
65 g_bioq_lock(struct g_bioq *bq)
66 {
67 
68 	mtx_lock(&bq->bio_queue_lock);
69 }
70 
71 static void
72 g_bioq_unlock(struct g_bioq *bq)
73 {
74 
75 	mtx_unlock(&bq->bio_queue_lock);
76 }
77 
78 #if 0
79 static void
80 g_bioq_destroy(struct g_bioq *bq)
81 {
82 
83 	mtx_destroy(&bq->bio_queue_lock);
84 }
85 #endif
86 
87 static void
88 g_bioq_init(struct g_bioq *bq)
89 {
90 
91 	TAILQ_INIT(&bq->bio_queue);
92 	mtx_init(&bq->bio_queue_lock, "bio queue", NULL, MTX_DEF);
93 }
94 
95 static struct bio *
96 g_bioq_first(struct g_bioq *bq)
97 {
98 	struct bio *bp;
99 
100 	bp = TAILQ_FIRST(&bq->bio_queue);
101 	if (bp != NULL) {
102 		KASSERT((bp->bio_flags & BIO_ONQUEUE),
103 		    ("Bio not on queue bp=%p target %p", bp, bq));
104 		bp->bio_flags &= ~BIO_ONQUEUE;
105 		TAILQ_REMOVE(&bq->bio_queue, bp, bio_queue);
106 		bq->bio_queue_length--;
107 	}
108 	return (bp);
109 }
110 
111 struct bio *
112 g_new_bio(void)
113 {
114 	struct bio *bp;
115 
116 	bp = uma_zalloc(biozone, M_NOWAIT | M_ZERO);
117 #ifdef KTR
118 	if (KTR_COMPILE & KTR_GEOM) {
119 		struct stack st;
120 
121 		CTR1(KTR_GEOM, "g_new_bio(): %p", bp);
122 		stack_save(&st);
123 		CTRSTACK(KTR_GEOM, &st, 3, 0);
124 	}
125 #endif
126 	return (bp);
127 }
128 
129 struct bio *
130 g_alloc_bio(void)
131 {
132 	struct bio *bp;
133 
134 	bp = uma_zalloc(biozone, M_WAITOK | M_ZERO);
135 #ifdef KTR
136 	if (KTR_COMPILE & KTR_GEOM) {
137 		struct stack st;
138 
139 		CTR1(KTR_GEOM, "g_alloc_bio(): %p", bp);
140 		stack_save(&st);
141 		CTRSTACK(KTR_GEOM, &st, 3, 0);
142 	}
143 #endif
144 	return (bp);
145 }
146 
147 void
148 g_destroy_bio(struct bio *bp)
149 {
150 #ifdef KTR
151 	if (KTR_COMPILE & KTR_GEOM) {
152 		struct stack st;
153 
154 		CTR1(KTR_GEOM, "g_destroy_bio(): %p", bp);
155 		stack_save(&st);
156 		CTRSTACK(KTR_GEOM, &st, 3, 0);
157 	}
158 #endif
159 	uma_zfree(biozone, bp);
160 }
161 
162 struct bio *
163 g_clone_bio(struct bio *bp)
164 {
165 	struct bio *bp2;
166 
167 	bp2 = uma_zalloc(biozone, M_NOWAIT | M_ZERO);
168 	if (bp2 != NULL) {
169 		bp2->bio_parent = bp;
170 		bp2->bio_cmd = bp->bio_cmd;
171 		bp2->bio_length = bp->bio_length;
172 		bp2->bio_offset = bp->bio_offset;
173 		bp2->bio_data = bp->bio_data;
174 		bp2->bio_attribute = bp->bio_attribute;
175 		bp->bio_children++;
176 	}
177 #ifdef KTR
178 	if (KTR_COMPILE & KTR_GEOM) {
179 		struct stack st;
180 
181 		CTR2(KTR_GEOM, "g_clone_bio(%p): %p", bp, bp2);
182 		stack_save(&st);
183 		CTRSTACK(KTR_GEOM, &st, 3, 0);
184 	}
185 #endif
186 	return(bp2);
187 }
188 
189 struct bio *
190 g_duplicate_bio(struct bio *bp)
191 {
192 	struct bio *bp2;
193 
194 	bp2 = uma_zalloc(biozone, M_WAITOK | M_ZERO);
195 	bp2->bio_parent = bp;
196 	bp2->bio_cmd = bp->bio_cmd;
197 	bp2->bio_length = bp->bio_length;
198 	bp2->bio_offset = bp->bio_offset;
199 	bp2->bio_data = bp->bio_data;
200 	bp2->bio_attribute = bp->bio_attribute;
201 	bp->bio_children++;
202 #ifdef KTR
203 	if (KTR_COMPILE & KTR_GEOM) {
204 		struct stack st;
205 
206 		CTR2(KTR_GEOM, "g_duplicate_bio(%p): %p", bp, bp2);
207 		stack_save(&st);
208 		CTRSTACK(KTR_GEOM, &st, 3, 0);
209 	}
210 #endif
211 	return(bp2);
212 }
213 
214 void
215 g_io_init()
216 {
217 
218 	g_bioq_init(&g_bio_run_down);
219 	g_bioq_init(&g_bio_run_up);
220 	g_bioq_init(&g_bio_run_task);
221 	biozone = uma_zcreate("g_bio", sizeof (struct bio),
222 	    NULL, NULL,
223 	    NULL, NULL,
224 	    0, 0);
225 }
226 
227 int
228 g_io_getattr(const char *attr, struct g_consumer *cp, int *len, void *ptr)
229 {
230 	struct bio *bp;
231 	int error;
232 
233 	g_trace(G_T_BIO, "bio_getattr(%s)", attr);
234 	bp = g_alloc_bio();
235 	bp->bio_cmd = BIO_GETATTR;
236 	bp->bio_done = NULL;
237 	bp->bio_attribute = attr;
238 	bp->bio_length = *len;
239 	bp->bio_data = ptr;
240 	g_io_request(bp, cp);
241 	error = biowait(bp, "ggetattr");
242 	*len = bp->bio_completed;
243 	g_destroy_bio(bp);
244 	return (error);
245 }
246 
247 static int
248 g_io_check(struct bio *bp)
249 {
250 	struct g_consumer *cp;
251 	struct g_provider *pp;
252 
253 	cp = bp->bio_from;
254 	pp = bp->bio_to;
255 
256 	/* Fail if access counters dont allow the operation */
257 	switch(bp->bio_cmd) {
258 	case BIO_READ:
259 	case BIO_GETATTR:
260 		if (cp->acr == 0)
261 			return (EPERM);
262 		break;
263 	case BIO_WRITE:
264 	case BIO_DELETE:
265 		if (cp->acw == 0)
266 			return (EPERM);
267 		break;
268 	default:
269 		return (EPERM);
270 	}
271 	/* if provider is marked for error, don't disturb. */
272 	if (pp->error)
273 		return (pp->error);
274 
275 	switch(bp->bio_cmd) {
276 	case BIO_READ:
277 	case BIO_WRITE:
278 	case BIO_DELETE:
279 		/* Zero sectorsize is a probably lack of media */
280 		if (pp->sectorsize == 0)
281 			return (ENXIO);
282 		/* Reject I/O not on sector boundary */
283 		if (bp->bio_offset % pp->sectorsize)
284 			return (EINVAL);
285 		/* Reject I/O not integral sector long */
286 		if (bp->bio_length % pp->sectorsize)
287 			return (EINVAL);
288 		/* Reject requests before or past the end of media. */
289 		if (bp->bio_offset < 0)
290 			return (EIO);
291 		if (bp->bio_offset > pp->mediasize)
292 			return (EIO);
293 		break;
294 	default:
295 		break;
296 	}
297 	return (0);
298 }
299 
300 void
301 g_io_request(struct bio *bp, struct g_consumer *cp)
302 {
303 	struct g_provider *pp;
304 
305 	KASSERT(cp != NULL, ("NULL cp in g_io_request"));
306 	KASSERT(bp != NULL, ("NULL bp in g_io_request"));
307 	KASSERT(bp->bio_data != NULL, ("NULL bp->data in g_io_request"));
308 	pp = cp->provider;
309 	KASSERT(pp != NULL, ("consumer not attached in g_io_request"));
310 #ifdef DIAGNOSTIC
311 	KASSERT(bp->bio_driver1 == NULL,
312 	    ("bio_driver1 used by the consumer (geom %s)", cp->geom->name));
313 	KASSERT(bp->bio_driver2 == NULL,
314 	    ("bio_driver2 used by the consumer (geom %s)", cp->geom->name));
315 	KASSERT(bp->bio_pflags == 0,
316 	    ("bio_pflags used by the consumer (geom %s)", cp->geom->name));
317 	/*
318 	 * Remember consumer's private fields, so we can detect if they were
319 	 * modified by the provider.
320 	 */
321 	bp->_bio_caller1 = bp->bio_caller1;
322 	bp->_bio_caller2 = bp->bio_caller2;
323 	bp->_bio_cflags = bp->bio_cflags;
324 #endif
325 
326 	if (bp->bio_cmd & (BIO_READ|BIO_WRITE|BIO_DELETE)) {
327 		KASSERT(bp->bio_offset % cp->provider->sectorsize == 0,
328 		    ("wrong offset %jd for sectorsize %u",
329 		    bp->bio_offset, cp->provider->sectorsize));
330 		KASSERT(bp->bio_length % cp->provider->sectorsize == 0,
331 		    ("wrong length %jd for sectorsize %u",
332 		    bp->bio_length, cp->provider->sectorsize));
333 	}
334 
335 	g_trace(G_T_BIO, "bio_request(%p) from %p(%s) to %p(%s) cmd %d",
336 	    bp, cp, cp->geom->name, pp, pp->name, bp->bio_cmd);
337 
338 	bp->bio_from = cp;
339 	bp->bio_to = pp;
340 	bp->bio_error = 0;
341 	bp->bio_completed = 0;
342 
343 	KASSERT(!(bp->bio_flags & BIO_ONQUEUE),
344 	    ("Bio already on queue bp=%p", bp));
345 	bp->bio_flags |= BIO_ONQUEUE;
346 
347 	binuptime(&bp->bio_t0);
348 
349 	/*
350 	 * The statistics collection is lockless, as such, but we
351 	 * can not update one instance of the statistics from more
352 	 * than one thread at a time, so grab the lock first.
353 	 */
354 	g_bioq_lock(&g_bio_run_down);
355 	if (g_collectstats & 1)
356 		devstat_start_transaction(pp->stat, &bp->bio_t0);
357 	if (g_collectstats & 2)
358 		devstat_start_transaction(cp->stat, &bp->bio_t0);
359 
360 	pp->nstart++;
361 	cp->nstart++;
362 	TAILQ_INSERT_TAIL(&g_bio_run_down.bio_queue, bp, bio_queue);
363 	g_bio_run_down.bio_queue_length++;
364 	g_bioq_unlock(&g_bio_run_down);
365 
366 	/* Pass it on down. */
367 	wakeup(&g_wait_down);
368 }
369 
370 void
371 g_io_deliver(struct bio *bp, int error)
372 {
373 	struct g_consumer *cp;
374 	struct g_provider *pp;
375 
376 	KASSERT(bp != NULL, ("NULL bp in g_io_deliver"));
377 	pp = bp->bio_to;
378 	KASSERT(pp != NULL, ("NULL bio_to in g_io_deliver"));
379 #ifdef DIAGNOSTIC
380 	KASSERT(bp->bio_caller1 == bp->_bio_caller1,
381 	    ("bio_caller1 used by the provider %s", pp->name));
382 	KASSERT(bp->bio_caller2 == bp->_bio_caller2,
383 	    ("bio_caller2 used by the provider %s", pp->name));
384 	KASSERT(bp->bio_cflags == bp->_bio_cflags,
385 	    ("bio_cflags used by the provider %s", pp->name));
386 #endif
387 	cp = bp->bio_from;
388 	if (cp == NULL) {
389 		bp->bio_error = error;
390 		bp->bio_done(bp);
391 		return;
392 	}
393 	KASSERT(cp != NULL, ("NULL bio_from in g_io_deliver"));
394 	KASSERT(cp->geom != NULL, ("NULL bio_from->geom in g_io_deliver"));
395 	KASSERT(bp->bio_completed >= 0, ("bio_completed can't be less than 0"));
396 	KASSERT(bp->bio_completed <= bp->bio_length,
397 	    ("bio_completed can't be greater than bio_length"));
398 
399 	g_trace(G_T_BIO,
400 "g_io_deliver(%p) from %p(%s) to %p(%s) cmd %d error %d off %jd len %jd",
401 	    bp, cp, cp->geom->name, pp, pp->name, bp->bio_cmd, error,
402 	    (intmax_t)bp->bio_offset, (intmax_t)bp->bio_length);
403 
404 	KASSERT(!(bp->bio_flags & BIO_ONQUEUE),
405 	    ("Bio already on queue bp=%p", bp));
406 
407 	/*
408 	 * XXX: next two doesn't belong here
409 	 */
410 	bp->bio_bcount = bp->bio_length;
411 	bp->bio_resid = bp->bio_bcount - bp->bio_completed;
412 
413 	/*
414 	 * The statistics collection is lockless, as such, but we
415 	 * can not update one instance of the statistics from more
416 	 * than one thread at a time, so grab the lock first.
417 	 */
418 	g_bioq_lock(&g_bio_run_up);
419 	if (g_collectstats & 1)
420 		devstat_end_transaction_bio(pp->stat, bp);
421 	if (g_collectstats & 2)
422 		devstat_end_transaction_bio(cp->stat, bp);
423 
424 	cp->nend++;
425 	pp->nend++;
426 	if (error != ENOMEM) {
427 		bp->bio_error = error;
428 		TAILQ_INSERT_TAIL(&g_bio_run_up.bio_queue, bp, bio_queue);
429 		bp->bio_flags |= BIO_ONQUEUE;
430 		g_bio_run_up.bio_queue_length++;
431 		g_bioq_unlock(&g_bio_run_up);
432 		wakeup(&g_wait_up);
433 		return;
434 	}
435 	g_bioq_unlock(&g_bio_run_up);
436 
437 	if (bootverbose)
438 		printf("ENOMEM %p on %p(%s)\n", bp, pp, pp->name);
439 	bp->bio_children = 0;
440 	bp->bio_inbed = 0;
441 	g_io_request(bp, cp);
442 	pace++;
443 	return;
444 }
445 
446 void
447 g_io_schedule_down(struct thread *tp __unused)
448 {
449 	struct bio *bp;
450 	off_t excess;
451 	int error;
452 
453 	for(;;) {
454 		g_bioq_lock(&g_bio_run_down);
455 		bp = g_bioq_first(&g_bio_run_down);
456 		if (bp == NULL) {
457 			CTR0(KTR_GEOM, "g_down going to sleep");
458 			msleep(&g_wait_down, &g_bio_run_down.bio_queue_lock,
459 			    PRIBIO | PDROP, "-", hz/10);
460 			continue;
461 		}
462 		CTR0(KTR_GEOM, "g_down has work to do");
463 		g_bioq_unlock(&g_bio_run_down);
464 		if (pace > 0) {
465 			CTR1(KTR_GEOM, "g_down pacing self (pace %d)", pace);
466 			msleep(&error, NULL, PRIBIO, "g_down", hz/10);
467 			pace--;
468 		}
469 		error = g_io_check(bp);
470 		if (error) {
471 			CTR3(KTR_GEOM, "g_down g_io_check on bp %p provider "
472 			    "%s returned %d", bp, bp->bio_to->name, error);
473 			g_io_deliver(bp, error);
474 			continue;
475 		}
476 		CTR2(KTR_GEOM, "g_down processing bp %p provider %s", bp,
477 		    bp->bio_to->name);
478 		switch (bp->bio_cmd) {
479 		case BIO_READ:
480 		case BIO_WRITE:
481 		case BIO_DELETE:
482 			/* Truncate requests to the end of providers media. */
483 			/*
484 			 * XXX: What if we truncate because of offset being
485 			 * bad, not length?
486 			 */
487 			excess = bp->bio_offset + bp->bio_length;
488 			if (excess > bp->bio_to->mediasize) {
489 				excess -= bp->bio_to->mediasize;
490 				bp->bio_length -= excess;
491 				if (excess > 0)
492 					CTR3(KTR_GEOM, "g_down truncated bio "
493 					    "%p provider %s by %d", bp,
494 					    bp->bio_to->name, excess);
495 			}
496 			/* Deliver zero length transfers right here. */
497 			if (bp->bio_length == 0) {
498 				g_io_deliver(bp, 0);
499 				CTR2(KTR_GEOM, "g_down terminated 0-length "
500 				    "bp %p provider %s", bp, bp->bio_to->name);
501 				continue;
502 			}
503 			break;
504 		default:
505 			break;
506 		}
507 		THREAD_NO_SLEEPING();
508 		CTR4(KTR_GEOM, "g_down starting bp %p provider %s off %ld "
509 		    "len %ld", bp, bp->bio_to->name, bp->bio_offset,
510 		    bp->bio_length);
511 		bp->bio_to->geom->start(bp);
512 		THREAD_SLEEPING_OK();
513 	}
514 }
515 
516 void
517 bio_taskqueue(struct bio *bp, bio_task_t *func, void *arg)
518 {
519 	bp->bio_task = func;
520 	bp->bio_task_arg = arg;
521 	/*
522 	 * The taskqueue is actually just a second queue off the "up"
523 	 * queue, so we use the same lock.
524 	 */
525 	g_bioq_lock(&g_bio_run_up);
526 	KASSERT(!(bp->bio_flags & BIO_ONQUEUE),
527 	    ("Bio already on queue bp=%p target taskq", bp));
528 	bp->bio_flags |= BIO_ONQUEUE;
529 	TAILQ_INSERT_TAIL(&g_bio_run_task.bio_queue, bp, bio_queue);
530 	g_bio_run_task.bio_queue_length++;
531 	wakeup(&g_wait_up);
532 	g_bioq_unlock(&g_bio_run_up);
533 }
534 
535 
536 void
537 g_io_schedule_up(struct thread *tp __unused)
538 {
539 	struct bio *bp;
540 	for(;;) {
541 		g_bioq_lock(&g_bio_run_up);
542 		bp = g_bioq_first(&g_bio_run_task);
543 		if (bp != NULL) {
544 			g_bioq_unlock(&g_bio_run_up);
545 			THREAD_NO_SLEEPING();
546 			CTR1(KTR_GEOM, "g_up processing task bp %p", bp);
547 			bp->bio_task(bp->bio_task_arg);
548 			THREAD_SLEEPING_OK();
549 			continue;
550 		}
551 		bp = g_bioq_first(&g_bio_run_up);
552 		if (bp != NULL) {
553 			g_bioq_unlock(&g_bio_run_up);
554 			THREAD_NO_SLEEPING();
555 			CTR4(KTR_GEOM, "g_up biodone bp %p provider %s off "
556 			    "%ld len %ld", bp, bp->bio_to->name,
557 			    bp->bio_offset, bp->bio_length);
558 			biodone(bp);
559 			THREAD_SLEEPING_OK();
560 			continue;
561 		}
562 		CTR0(KTR_GEOM, "g_up going to sleep");
563 		msleep(&g_wait_up, &g_bio_run_up.bio_queue_lock,
564 		    PRIBIO | PDROP, "-", hz/10);
565 	}
566 }
567 
568 void *
569 g_read_data(struct g_consumer *cp, off_t offset, off_t length, int *error)
570 {
571 	struct bio *bp;
572 	void *ptr;
573 	int errorc;
574 
575 	KASSERT(length > 0 && length >= cp->provider->sectorsize &&
576 	    length <= MAXPHYS, ("g_read_data(): invalid length %jd",
577 	    (intmax_t)length));
578 
579 	bp = g_alloc_bio();
580 	bp->bio_cmd = BIO_READ;
581 	bp->bio_done = NULL;
582 	bp->bio_offset = offset;
583 	bp->bio_length = length;
584 	ptr = g_malloc(length, M_WAITOK);
585 	bp->bio_data = ptr;
586 	g_io_request(bp, cp);
587 	errorc = biowait(bp, "gread");
588 	if (error != NULL)
589 		*error = errorc;
590 	g_destroy_bio(bp);
591 	if (errorc) {
592 		g_free(ptr);
593 		ptr = NULL;
594 	}
595 	return (ptr);
596 }
597 
598 int
599 g_write_data(struct g_consumer *cp, off_t offset, void *ptr, off_t length)
600 {
601 	struct bio *bp;
602 	int error;
603 
604 	KASSERT(length > 0 && length >= cp->provider->sectorsize &&
605 	    length <= MAXPHYS, ("g_write_data(): invalid length %jd",
606 	    (intmax_t)length));
607 
608 	bp = g_alloc_bio();
609 	bp->bio_cmd = BIO_WRITE;
610 	bp->bio_done = NULL;
611 	bp->bio_offset = offset;
612 	bp->bio_length = length;
613 	bp->bio_data = ptr;
614 	g_io_request(bp, cp);
615 	error = biowait(bp, "gwrite");
616 	g_destroy_bio(bp);
617 	return (error);
618 }
619 
620 void
621 g_print_bio(struct bio *bp)
622 {
623 	const char *pname, *cmd = NULL;
624 
625 	if (bp->bio_to != NULL)
626 		pname = bp->bio_to->name;
627 	else
628 		pname = "[unknown]";
629 
630 	switch (bp->bio_cmd) {
631 	case BIO_GETATTR:
632 		cmd = "GETATTR";
633 		printf("%s[%s(attr=%s)]", pname, cmd, bp->bio_attribute);
634 		return;
635 	case BIO_READ:
636 		cmd = "READ";
637 	case BIO_WRITE:
638 		if (cmd == NULL)
639 			cmd = "WRITE";
640 	case BIO_DELETE:
641 		if (cmd == NULL)
642 			cmd = "DELETE";
643 		printf("%s[%s(offset=%jd, length=%jd)]", pname, cmd,
644 		    (intmax_t)bp->bio_offset, (intmax_t)bp->bio_length);
645 		return;
646 	default:
647 		cmd = "UNKNOWN";
648 		printf("%s[%s()]", pname, cmd);
649 		return;
650 	}
651 	/* NOTREACHED */
652 }
653