1 /*-
2 * Copyright (c) 2013 Peter Grehan <grehan@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD$
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <sys/param.h>
33 #include <sys/queue.h>
34 #include <sys/errno.h>
35 #include <sys/stat.h>
36 #include <sys/ioctl.h>
37 #include <sys/disk.h>
38
39 #include <assert.h>
40 #include <fcntl.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <pthread.h>
45 #include <pthread_np.h>
46 #include <signal.h>
47 #include <unistd.h>
48
49 #include <machine/atomic.h>
50
51 #include "bhyverun.h"
52 #include "mevent.h"
53 #include "block_if.h"
54
55 #define BLOCKIF_SIG 0xb109b109
56
57 #define BLOCKIF_NUMTHR 8
58 #define BLOCKIF_MAXREQ (64 + BLOCKIF_NUMTHR)
59
60 enum blockop {
61 BOP_READ,
62 BOP_WRITE,
63 BOP_FLUSH,
64 BOP_DELETE
65 };
66
67 enum blockstat {
68 BST_FREE,
69 BST_BLOCK,
70 BST_PEND,
71 BST_BUSY,
72 BST_DONE
73 };
74
75 struct blockif_elem {
76 TAILQ_ENTRY(blockif_elem) be_link;
77 struct blockif_req *be_req;
78 enum blockop be_op;
79 enum blockstat be_status;
80 pthread_t be_tid;
81 off_t be_block;
82 };
83
84 struct blockif_ctxt {
85 int bc_magic;
86 int bc_fd;
87 int bc_ischr;
88 int bc_isgeom;
89 int bc_candelete;
90 int bc_rdonly;
91 off_t bc_size;
92 int bc_sectsz;
93 int bc_psectsz;
94 int bc_psectoff;
95 int bc_closing;
96 pthread_t bc_btid[BLOCKIF_NUMTHR];
97 pthread_mutex_t bc_mtx;
98 pthread_cond_t bc_cond;
99
100 /* Request elements and free/pending/busy queues */
101 TAILQ_HEAD(, blockif_elem) bc_freeq;
102 TAILQ_HEAD(, blockif_elem) bc_pendq;
103 TAILQ_HEAD(, blockif_elem) bc_busyq;
104 struct blockif_elem bc_reqs[BLOCKIF_MAXREQ];
105 };
106
107 static pthread_once_t blockif_once = PTHREAD_ONCE_INIT;
108
109 struct blockif_sig_elem {
110 pthread_mutex_t bse_mtx;
111 pthread_cond_t bse_cond;
112 int bse_pending;
113 struct blockif_sig_elem *bse_next;
114 };
115
116 static struct blockif_sig_elem *blockif_bse_head;
117
118 static int
blockif_enqueue(struct blockif_ctxt * bc,struct blockif_req * breq,enum blockop op)119 blockif_enqueue(struct blockif_ctxt *bc, struct blockif_req *breq,
120 enum blockop op)
121 {
122 struct blockif_elem *be, *tbe;
123 off_t off;
124 int i;
125
126 be = TAILQ_FIRST(&bc->bc_freeq);
127 assert(be != NULL);
128 assert(be->be_status == BST_FREE);
129 TAILQ_REMOVE(&bc->bc_freeq, be, be_link);
130 be->be_req = breq;
131 be->be_op = op;
132 switch (op) {
133 case BOP_READ:
134 case BOP_WRITE:
135 case BOP_DELETE:
136 off = breq->br_offset;
137 for (i = 0; i < breq->br_iovcnt; i++)
138 off += breq->br_iov[i].iov_len;
139 break;
140 default:
141 off = OFF_MAX;
142 }
143 be->be_block = off;
144 TAILQ_FOREACH(tbe, &bc->bc_pendq, be_link) {
145 if (tbe->be_block == breq->br_offset)
146 break;
147 }
148 if (tbe == NULL) {
149 TAILQ_FOREACH(tbe, &bc->bc_busyq, be_link) {
150 if (tbe->be_block == breq->br_offset)
151 break;
152 }
153 }
154 if (tbe == NULL)
155 be->be_status = BST_PEND;
156 else
157 be->be_status = BST_BLOCK;
158 TAILQ_INSERT_TAIL(&bc->bc_pendq, be, be_link);
159 return (be->be_status == BST_PEND);
160 }
161
162 static int
blockif_dequeue(struct blockif_ctxt * bc,pthread_t t,struct blockif_elem ** bep)163 blockif_dequeue(struct blockif_ctxt *bc, pthread_t t, struct blockif_elem **bep)
164 {
165 struct blockif_elem *be;
166
167 TAILQ_FOREACH(be, &bc->bc_pendq, be_link) {
168 if (be->be_status == BST_PEND)
169 break;
170 assert(be->be_status == BST_BLOCK);
171 }
172 if (be == NULL)
173 return (0);
174 TAILQ_REMOVE(&bc->bc_pendq, be, be_link);
175 be->be_status = BST_BUSY;
176 be->be_tid = t;
177 TAILQ_INSERT_TAIL(&bc->bc_busyq, be, be_link);
178 *bep = be;
179 return (1);
180 }
181
182 static void
blockif_complete(struct blockif_ctxt * bc,struct blockif_elem * be)183 blockif_complete(struct blockif_ctxt *bc, struct blockif_elem *be)
184 {
185 struct blockif_elem *tbe;
186
187 if (be->be_status == BST_DONE || be->be_status == BST_BUSY)
188 TAILQ_REMOVE(&bc->bc_busyq, be, be_link);
189 else
190 TAILQ_REMOVE(&bc->bc_pendq, be, be_link);
191 TAILQ_FOREACH(tbe, &bc->bc_pendq, be_link) {
192 if (tbe->be_req->br_offset == be->be_block)
193 tbe->be_status = BST_PEND;
194 }
195 be->be_tid = 0;
196 be->be_status = BST_FREE;
197 be->be_req = NULL;
198 TAILQ_INSERT_TAIL(&bc->bc_freeq, be, be_link);
199 }
200
201 static void
blockif_proc(struct blockif_ctxt * bc,struct blockif_elem * be,uint8_t * buf)202 blockif_proc(struct blockif_ctxt *bc, struct blockif_elem *be, uint8_t *buf)
203 {
204 struct blockif_req *br;
205 off_t arg[2];
206 ssize_t clen, len, off, boff, voff;
207 int i, err;
208
209 br = be->be_req;
210 if (br->br_iovcnt <= 1)
211 buf = NULL;
212 err = 0;
213 switch (be->be_op) {
214 case BOP_READ:
215 if (buf == NULL) {
216 if ((len = preadv(bc->bc_fd, br->br_iov, br->br_iovcnt,
217 br->br_offset)) < 0)
218 err = errno;
219 else
220 br->br_resid -= len;
221 break;
222 }
223 i = 0;
224 off = voff = 0;
225 while (br->br_resid > 0) {
226 len = MIN(br->br_resid, MAXPHYS);
227 if (pread(bc->bc_fd, buf, len, br->br_offset +
228 off) < 0) {
229 err = errno;
230 break;
231 }
232 boff = 0;
233 do {
234 clen = MIN(len - boff, br->br_iov[i].iov_len -
235 voff);
236 memcpy(br->br_iov[i].iov_base + voff,
237 buf + boff, clen);
238 if (clen < br->br_iov[i].iov_len - voff)
239 voff += clen;
240 else {
241 i++;
242 voff = 0;
243 }
244 boff += clen;
245 } while (boff < len);
246 off += len;
247 br->br_resid -= len;
248 }
249 break;
250 case BOP_WRITE:
251 if (bc->bc_rdonly) {
252 err = EROFS;
253 break;
254 }
255 if (buf == NULL) {
256 if ((len = pwritev(bc->bc_fd, br->br_iov, br->br_iovcnt,
257 br->br_offset)) < 0)
258 err = errno;
259 else
260 br->br_resid -= len;
261 break;
262 }
263 i = 0;
264 off = voff = 0;
265 while (br->br_resid > 0) {
266 len = MIN(br->br_resid, MAXPHYS);
267 boff = 0;
268 do {
269 clen = MIN(len - boff, br->br_iov[i].iov_len -
270 voff);
271 memcpy(buf + boff,
272 br->br_iov[i].iov_base + voff, clen);
273 if (clen < br->br_iov[i].iov_len - voff)
274 voff += clen;
275 else {
276 i++;
277 voff = 0;
278 }
279 boff += clen;
280 } while (boff < len);
281 if (pwrite(bc->bc_fd, buf, len, br->br_offset +
282 off) < 0) {
283 err = errno;
284 break;
285 }
286 off += len;
287 br->br_resid -= len;
288 }
289 break;
290 case BOP_FLUSH:
291 if (bc->bc_ischr) {
292 if (ioctl(bc->bc_fd, DIOCGFLUSH))
293 err = errno;
294 } else if (fsync(bc->bc_fd))
295 err = errno;
296 break;
297 case BOP_DELETE:
298 if (!bc->bc_candelete)
299 err = EOPNOTSUPP;
300 else if (bc->bc_rdonly)
301 err = EROFS;
302 else if (bc->bc_ischr) {
303 arg[0] = br->br_offset;
304 arg[1] = br->br_resid;
305 if (ioctl(bc->bc_fd, DIOCGDELETE, arg))
306 err = errno;
307 else
308 br->br_resid = 0;
309 } else
310 err = EOPNOTSUPP;
311 break;
312 default:
313 err = EINVAL;
314 break;
315 }
316
317 be->be_status = BST_DONE;
318
319 (*br->br_callback)(br, err);
320 }
321
322 static void *
blockif_thr(void * arg)323 blockif_thr(void *arg)
324 {
325 struct blockif_ctxt *bc;
326 struct blockif_elem *be;
327 pthread_t t;
328 uint8_t *buf;
329
330 bc = arg;
331 if (bc->bc_isgeom)
332 buf = malloc(MAXPHYS);
333 else
334 buf = NULL;
335 t = pthread_self();
336
337 pthread_mutex_lock(&bc->bc_mtx);
338 for (;;) {
339 while (blockif_dequeue(bc, t, &be)) {
340 pthread_mutex_unlock(&bc->bc_mtx);
341 blockif_proc(bc, be, buf);
342 pthread_mutex_lock(&bc->bc_mtx);
343 blockif_complete(bc, be);
344 }
345 /* Check ctxt status here to see if exit requested */
346 if (bc->bc_closing)
347 break;
348 pthread_cond_wait(&bc->bc_cond, &bc->bc_mtx);
349 }
350 pthread_mutex_unlock(&bc->bc_mtx);
351
352 if (buf)
353 free(buf);
354 pthread_exit(NULL);
355 return (NULL);
356 }
357
358 static void
blockif_sigcont_handler(int signal,enum ev_type type,void * arg)359 blockif_sigcont_handler(int signal, enum ev_type type, void *arg)
360 {
361 struct blockif_sig_elem *bse;
362
363 for (;;) {
364 /*
365 * Process the entire list even if not intended for
366 * this thread.
367 */
368 do {
369 bse = blockif_bse_head;
370 if (bse == NULL)
371 return;
372 } while (!atomic_cmpset_ptr((uintptr_t *)&blockif_bse_head,
373 (uintptr_t)bse,
374 (uintptr_t)bse->bse_next));
375
376 pthread_mutex_lock(&bse->bse_mtx);
377 bse->bse_pending = 0;
378 pthread_cond_signal(&bse->bse_cond);
379 pthread_mutex_unlock(&bse->bse_mtx);
380 }
381 }
382
383 static void
blockif_init(void)384 blockif_init(void)
385 {
386 mevent_add(SIGCONT, EVF_SIGNAL, blockif_sigcont_handler, NULL);
387 (void) signal(SIGCONT, SIG_IGN);
388 }
389
390 struct blockif_ctxt *
blockif_open(const char * optstr,const char * ident)391 blockif_open(const char *optstr, const char *ident)
392 {
393 char tname[MAXCOMLEN + 1];
394 char name[MAXPATHLEN];
395 char *nopt, *xopts, *cp;
396 struct blockif_ctxt *bc;
397 struct stat sbuf;
398 struct diocgattr_arg arg;
399 off_t size, psectsz, psectoff;
400 int extra, fd, i, sectsz;
401 int nocache, sync, ro, candelete, geom, ssopt, pssopt;
402
403 pthread_once(&blockif_once, blockif_init);
404
405 fd = -1;
406 ssopt = 0;
407 nocache = 0;
408 sync = 0;
409 ro = 0;
410
411 /*
412 * The first element in the optstring is always a pathname.
413 * Optional elements follow
414 */
415 nopt = xopts = strdup(optstr);
416 while (xopts != NULL) {
417 cp = strsep(&xopts, ",");
418 if (cp == nopt) /* file or device pathname */
419 continue;
420 else if (!strcmp(cp, "nocache"))
421 nocache = 1;
422 else if (!strcmp(cp, "sync") || !strcmp(cp, "direct"))
423 sync = 1;
424 else if (!strcmp(cp, "ro"))
425 ro = 1;
426 else if (sscanf(cp, "sectorsize=%d/%d", &ssopt, &pssopt) == 2)
427 ;
428 else if (sscanf(cp, "sectorsize=%d", &ssopt) == 1)
429 pssopt = ssopt;
430 else {
431 fprintf(stderr, "Invalid device option \"%s\"\n", cp);
432 goto err;
433 }
434 }
435
436 extra = 0;
437 if (nocache)
438 extra |= O_DIRECT;
439 if (sync)
440 extra |= O_SYNC;
441
442 fd = open(nopt, (ro ? O_RDONLY : O_RDWR) | extra);
443 if (fd < 0 && !ro) {
444 /* Attempt a r/w fail with a r/o open */
445 fd = open(nopt, O_RDONLY | extra);
446 ro = 1;
447 }
448
449 if (fd < 0) {
450 perror("Could not open backing file");
451 goto err;
452 }
453
454 if (fstat(fd, &sbuf) < 0) {
455 perror("Could not stat backing file");
456 goto err;
457 }
458
459 /*
460 * Deal with raw devices
461 */
462 size = sbuf.st_size;
463 sectsz = DEV_BSIZE;
464 psectsz = psectoff = 0;
465 candelete = geom = 0;
466 if (S_ISCHR(sbuf.st_mode)) {
467 if (ioctl(fd, DIOCGMEDIASIZE, &size) < 0 ||
468 ioctl(fd, DIOCGSECTORSIZE, §sz)) {
469 perror("Could not fetch dev blk/sector size");
470 goto err;
471 }
472 assert(size != 0);
473 assert(sectsz != 0);
474 if (ioctl(fd, DIOCGSTRIPESIZE, &psectsz) == 0 && psectsz > 0)
475 ioctl(fd, DIOCGSTRIPEOFFSET, &psectoff);
476 strlcpy(arg.name, "GEOM::candelete", sizeof(arg.name));
477 arg.len = sizeof(arg.value.i);
478 if (ioctl(fd, DIOCGATTR, &arg) == 0)
479 candelete = arg.value.i;
480 if (ioctl(fd, DIOCGPROVIDERNAME, name) == 0)
481 geom = 1;
482 } else
483 psectsz = sbuf.st_blksize;
484
485 if (ssopt != 0) {
486 if (!powerof2(ssopt) || !powerof2(pssopt) || ssopt < 512 ||
487 ssopt > pssopt) {
488 fprintf(stderr, "Invalid sector size %d/%d\n",
489 ssopt, pssopt);
490 goto err;
491 }
492
493 /*
494 * Some backend drivers (e.g. cd0, ada0) require that the I/O
495 * size be a multiple of the device's sector size.
496 *
497 * Validate that the emulated sector size complies with this
498 * requirement.
499 */
500 if (S_ISCHR(sbuf.st_mode)) {
501 if (ssopt < sectsz || (ssopt % sectsz) != 0) {
502 fprintf(stderr, "Sector size %d incompatible "
503 "with underlying device sector size %d\n",
504 ssopt, sectsz);
505 goto err;
506 }
507 }
508
509 sectsz = ssopt;
510 psectsz = pssopt;
511 psectoff = 0;
512 }
513
514 bc = calloc(1, sizeof(struct blockif_ctxt));
515 if (bc == NULL) {
516 perror("calloc");
517 goto err;
518 }
519
520 bc->bc_magic = BLOCKIF_SIG;
521 bc->bc_fd = fd;
522 bc->bc_ischr = S_ISCHR(sbuf.st_mode);
523 bc->bc_isgeom = geom;
524 bc->bc_candelete = candelete;
525 bc->bc_rdonly = ro;
526 bc->bc_size = size;
527 bc->bc_sectsz = sectsz;
528 bc->bc_psectsz = psectsz;
529 bc->bc_psectoff = psectoff;
530 pthread_mutex_init(&bc->bc_mtx, NULL);
531 pthread_cond_init(&bc->bc_cond, NULL);
532 TAILQ_INIT(&bc->bc_freeq);
533 TAILQ_INIT(&bc->bc_pendq);
534 TAILQ_INIT(&bc->bc_busyq);
535 for (i = 0; i < BLOCKIF_MAXREQ; i++) {
536 bc->bc_reqs[i].be_status = BST_FREE;
537 TAILQ_INSERT_HEAD(&bc->bc_freeq, &bc->bc_reqs[i], be_link);
538 }
539
540 for (i = 0; i < BLOCKIF_NUMTHR; i++) {
541 pthread_create(&bc->bc_btid[i], NULL, blockif_thr, bc);
542 snprintf(tname, sizeof(tname), "blk-%s-%d", ident, i);
543 pthread_set_name_np(bc->bc_btid[i], tname);
544 }
545
546 return (bc);
547 err:
548 if (fd >= 0)
549 close(fd);
550 return (NULL);
551 }
552
553 static int
blockif_request(struct blockif_ctxt * bc,struct blockif_req * breq,enum blockop op)554 blockif_request(struct blockif_ctxt *bc, struct blockif_req *breq,
555 enum blockop op)
556 {
557 int err;
558
559 err = 0;
560
561 pthread_mutex_lock(&bc->bc_mtx);
562 if (!TAILQ_EMPTY(&bc->bc_freeq)) {
563 /*
564 * Enqueue and inform the block i/o thread
565 * that there is work available
566 */
567 if (blockif_enqueue(bc, breq, op))
568 pthread_cond_signal(&bc->bc_cond);
569 } else {
570 /*
571 * Callers are not allowed to enqueue more than
572 * the specified blockif queue limit. Return an
573 * error to indicate that the queue length has been
574 * exceeded.
575 */
576 err = E2BIG;
577 }
578 pthread_mutex_unlock(&bc->bc_mtx);
579
580 return (err);
581 }
582
583 int
blockif_read(struct blockif_ctxt * bc,struct blockif_req * breq)584 blockif_read(struct blockif_ctxt *bc, struct blockif_req *breq)
585 {
586
587 assert(bc->bc_magic == BLOCKIF_SIG);
588 return (blockif_request(bc, breq, BOP_READ));
589 }
590
591 int
blockif_write(struct blockif_ctxt * bc,struct blockif_req * breq)592 blockif_write(struct blockif_ctxt *bc, struct blockif_req *breq)
593 {
594
595 assert(bc->bc_magic == BLOCKIF_SIG);
596 return (blockif_request(bc, breq, BOP_WRITE));
597 }
598
599 int
blockif_flush(struct blockif_ctxt * bc,struct blockif_req * breq)600 blockif_flush(struct blockif_ctxt *bc, struct blockif_req *breq)
601 {
602
603 assert(bc->bc_magic == BLOCKIF_SIG);
604 return (blockif_request(bc, breq, BOP_FLUSH));
605 }
606
607 int
blockif_delete(struct blockif_ctxt * bc,struct blockif_req * breq)608 blockif_delete(struct blockif_ctxt *bc, struct blockif_req *breq)
609 {
610
611 assert(bc->bc_magic == BLOCKIF_SIG);
612 return (blockif_request(bc, breq, BOP_DELETE));
613 }
614
615 int
blockif_cancel(struct blockif_ctxt * bc,struct blockif_req * breq)616 blockif_cancel(struct blockif_ctxt *bc, struct blockif_req *breq)
617 {
618 struct blockif_elem *be;
619
620 assert(bc->bc_magic == BLOCKIF_SIG);
621
622 pthread_mutex_lock(&bc->bc_mtx);
623 /*
624 * Check pending requests.
625 */
626 TAILQ_FOREACH(be, &bc->bc_pendq, be_link) {
627 if (be->be_req == breq)
628 break;
629 }
630 if (be != NULL) {
631 /*
632 * Found it.
633 */
634 blockif_complete(bc, be);
635 pthread_mutex_unlock(&bc->bc_mtx);
636
637 return (0);
638 }
639
640 /*
641 * Check in-flight requests.
642 */
643 TAILQ_FOREACH(be, &bc->bc_busyq, be_link) {
644 if (be->be_req == breq)
645 break;
646 }
647 if (be == NULL) {
648 /*
649 * Didn't find it.
650 */
651 pthread_mutex_unlock(&bc->bc_mtx);
652 return (EINVAL);
653 }
654
655 /*
656 * Interrupt the processing thread to force it return
657 * prematurely via it's normal callback path.
658 */
659 while (be->be_status == BST_BUSY) {
660 struct blockif_sig_elem bse, *old_head;
661
662 pthread_mutex_init(&bse.bse_mtx, NULL);
663 pthread_cond_init(&bse.bse_cond, NULL);
664
665 bse.bse_pending = 1;
666
667 do {
668 old_head = blockif_bse_head;
669 bse.bse_next = old_head;
670 } while (!atomic_cmpset_ptr((uintptr_t *)&blockif_bse_head,
671 (uintptr_t)old_head,
672 (uintptr_t)&bse));
673
674 pthread_kill(be->be_tid, SIGCONT);
675
676 pthread_mutex_lock(&bse.bse_mtx);
677 while (bse.bse_pending)
678 pthread_cond_wait(&bse.bse_cond, &bse.bse_mtx);
679 pthread_mutex_unlock(&bse.bse_mtx);
680 }
681
682 pthread_mutex_unlock(&bc->bc_mtx);
683
684 /*
685 * The processing thread has been interrupted. Since it's not
686 * clear if the callback has been invoked yet, return EBUSY.
687 */
688 return (EBUSY);
689 }
690
691 int
blockif_close(struct blockif_ctxt * bc)692 blockif_close(struct blockif_ctxt *bc)
693 {
694 void *jval;
695 int err, i;
696
697 err = 0;
698
699 assert(bc->bc_magic == BLOCKIF_SIG);
700
701 /*
702 * Stop the block i/o thread
703 */
704 pthread_mutex_lock(&bc->bc_mtx);
705 bc->bc_closing = 1;
706 pthread_mutex_unlock(&bc->bc_mtx);
707 pthread_cond_broadcast(&bc->bc_cond);
708 for (i = 0; i < BLOCKIF_NUMTHR; i++)
709 pthread_join(bc->bc_btid[i], &jval);
710
711 /* XXX Cancel queued i/o's ??? */
712
713 /*
714 * Release resources
715 */
716 bc->bc_magic = 0;
717 close(bc->bc_fd);
718 free(bc);
719
720 return (0);
721 }
722
723 /*
724 * Return virtual C/H/S values for a given block. Use the algorithm
725 * outlined in the VHD specification to calculate values.
726 */
727 void
blockif_chs(struct blockif_ctxt * bc,uint16_t * c,uint8_t * h,uint8_t * s)728 blockif_chs(struct blockif_ctxt *bc, uint16_t *c, uint8_t *h, uint8_t *s)
729 {
730 off_t sectors; /* total sectors of the block dev */
731 off_t hcyl; /* cylinders times heads */
732 uint16_t secpt; /* sectors per track */
733 uint8_t heads;
734
735 assert(bc->bc_magic == BLOCKIF_SIG);
736
737 sectors = bc->bc_size / bc->bc_sectsz;
738
739 /* Clamp the size to the largest possible with CHS */
740 if (sectors > 65535UL*16*255)
741 sectors = 65535UL*16*255;
742
743 if (sectors >= 65536UL*16*63) {
744 secpt = 255;
745 heads = 16;
746 hcyl = sectors / secpt;
747 } else {
748 secpt = 17;
749 hcyl = sectors / secpt;
750 heads = (hcyl + 1023) / 1024;
751
752 if (heads < 4)
753 heads = 4;
754
755 if (hcyl >= (heads * 1024) || heads > 16) {
756 secpt = 31;
757 heads = 16;
758 hcyl = sectors / secpt;
759 }
760 if (hcyl >= (heads * 1024)) {
761 secpt = 63;
762 heads = 16;
763 hcyl = sectors / secpt;
764 }
765 }
766
767 *c = hcyl / heads;
768 *h = heads;
769 *s = secpt;
770 }
771
772 /*
773 * Accessors
774 */
775 off_t
blockif_size(struct blockif_ctxt * bc)776 blockif_size(struct blockif_ctxt *bc)
777 {
778
779 assert(bc->bc_magic == BLOCKIF_SIG);
780 return (bc->bc_size);
781 }
782
783 int
blockif_sectsz(struct blockif_ctxt * bc)784 blockif_sectsz(struct blockif_ctxt *bc)
785 {
786
787 assert(bc->bc_magic == BLOCKIF_SIG);
788 return (bc->bc_sectsz);
789 }
790
791 void
blockif_psectsz(struct blockif_ctxt * bc,int * size,int * off)792 blockif_psectsz(struct blockif_ctxt *bc, int *size, int *off)
793 {
794
795 assert(bc->bc_magic == BLOCKIF_SIG);
796 *size = bc->bc_psectsz;
797 *off = bc->bc_psectoff;
798 }
799
800 int
blockif_queuesz(struct blockif_ctxt * bc)801 blockif_queuesz(struct blockif_ctxt *bc)
802 {
803
804 assert(bc->bc_magic == BLOCKIF_SIG);
805 return (BLOCKIF_MAXREQ - 1);
806 }
807
808 int
blockif_is_ro(struct blockif_ctxt * bc)809 blockif_is_ro(struct blockif_ctxt *bc)
810 {
811
812 assert(bc->bc_magic == BLOCKIF_SIG);
813 return (bc->bc_rdonly);
814 }
815
816 int
blockif_candelete(struct blockif_ctxt * bc)817 blockif_candelete(struct blockif_ctxt *bc)
818 {
819
820 assert(bc->bc_magic == BLOCKIF_SIG);
821 return (bc->bc_candelete);
822 }
823