usr.sbin/bhyve/block_if.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2013  Peter Grehan <grehan@freebsd.org>
   5  * All rights reserved.
   6  * Copyright 2020 Joyent, 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  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD$
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include <sys/param.h>
  36 #ifndef WITHOUT_CAPSICUM
  37 #include <sys/capsicum.h>
  38 #endif
  39 #include <sys/queue.h>
  40 #include <sys/errno.h>
  41 #include <sys/stat.h>
  42 #include <sys/ioctl.h>
  43 #include <sys/disk.h>
  44
  45 #include <assert.h>
  46 #ifndef WITHOUT_CAPSICUM
  47 #include <capsicum_helpers.h>
  48 #endif
  49 #include <err.h>
  50 #include <fcntl.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54 #include <pthread.h>
  55 #include <pthread_np.h>
  56 #include <signal.h>
  57 #include <sysexits.h>
  58 #include <unistd.h>
  59
  60 #include <machine/atomic.h>
  61
  62 #include "bhyverun.h"
  63 #include "debug.h"
  64 #include "mevent.h"
  65 #include "block_if.h"
  66
  67 #define BLOCKIF_SIG     0xb109b109
  68
  69 #define BLOCKIF_NUMTHR  8
  70 #define BLOCKIF_MAXREQ  (BLOCKIF_RING_MAX + BLOCKIF_NUMTHR)
  71
  72 enum blockop {
  73         BOP_READ,
  74         BOP_WRITE,
  75         BOP_FLUSH,
  76         BOP_DELETE
  77 };
  78
  79 enum blockstat {
  80         BST_FREE,
  81         BST_BLOCK,
  82         BST_PEND,
  83         BST_BUSY,
  84         BST_DONE
  85 };
  86
  87 struct blockif_elem {
  88         TAILQ_ENTRY(blockif_elem) be_link;
  89         struct blockif_req  *be_req;
  90         enum blockop         be_op;
  91         enum blockstat       be_status;
  92         pthread_t            be_tid;
  93         off_t                be_block;
  94 };
  95
  96 struct blockif_ctxt {
  97         int                     bc_magic;
  98         int                     bc_fd;
  99         int                     bc_ischr;
 100         int                     bc_isgeom;
 101         int                     bc_candelete;
 102         int                     bc_rdonly;
 103         off_t                   bc_size;
 104         int                     bc_sectsz;
 105         int                     bc_psectsz;
 106         int                     bc_psectoff;
 107         int                     bc_closing;
 108         pthread_t               bc_btid[BLOCKIF_NUMTHR];
 109         pthread_mutex_t         bc_mtx;
 110         pthread_cond_t          bc_cond;
 111
 112         /* Request elements and free/pending/busy queues */
 113         TAILQ_HEAD(, blockif_elem) bc_freeq;
 114         TAILQ_HEAD(, blockif_elem) bc_pendq;
 115         TAILQ_HEAD(, blockif_elem) bc_busyq;
 116         struct blockif_elem     bc_reqs[BLOCKIF_MAXREQ];
 117 };
 118
 119 static pthread_once_t blockif_once = PTHREAD_ONCE_INIT;
 120
 121 struct blockif_sig_elem {
 122         pthread_mutex_t                 bse_mtx;
 123         pthread_cond_t                  bse_cond;
 124         int                             bse_pending;
 125         struct blockif_sig_elem         *bse_next;
 126 };
 127
 128 static struct blockif_sig_elem *blockif_bse_head;
 129
 130 static int
 131 blockif_enqueue(struct blockif_ctxt *bc, struct blockif_req *breq,
 132                 enum blockop op)
 133 {
 134         struct blockif_elem *be, *tbe;
 135         off_t off;
 136         int i;
 137
 138         be = TAILQ_FIRST(&bc->bc_freeq);
 139         assert(be != NULL);
 140         assert(be->be_status == BST_FREE);
 141         TAILQ_REMOVE(&bc->bc_freeq, be, be_link);
 142         be->be_req = breq;
 143         be->be_op = op;
 144         switch (op) {
 145         case BOP_READ:
 146         case BOP_WRITE:
 147         case BOP_DELETE:
 148                 off = breq->br_offset;
 149                 for (i = 0; i < breq->br_iovcnt; i++)
 150                         off += breq->br_iov[i].iov_len;
 151                 break;
 152         default:
 153                 off = OFF_MAX;
 154         }
 155         be->be_block = off;
 156         TAILQ_FOREACH(tbe, &bc->bc_pendq, be_link) {
 157                 if (tbe->be_block == breq->br_offset)
 158                         break;
 159         }
 160         if (tbe == NULL) {
 161                 TAILQ_FOREACH(tbe, &bc->bc_busyq, be_link) {
 162                         if (tbe->be_block == breq->br_offset)
 163                                 break;
 164                 }
 165         }
 166         if (tbe == NULL)
 167                 be->be_status = BST_PEND;
 168         else
 169                 be->be_status = BST_BLOCK;
 170         TAILQ_INSERT_TAIL(&bc->bc_pendq, be, be_link);
 171         return (be->be_status == BST_PEND);
 172 }
 173
 174 static int
 175 blockif_dequeue(struct blockif_ctxt *bc, pthread_t t, struct blockif_elem **bep)
 176 {
 177         struct blockif_elem *be;
 178
 179         TAILQ_FOREACH(be, &bc->bc_pendq, be_link) {
 180                 if (be->be_status == BST_PEND)
 181                         break;
 182                 assert(be->be_status == BST_BLOCK);
 183         }
 184         if (be == NULL)
 185                 return (0);
 186         TAILQ_REMOVE(&bc->bc_pendq, be, be_link);
 187         be->be_status = BST_BUSY;
 188         be->be_tid = t;
 189         TAILQ_INSERT_TAIL(&bc->bc_busyq, be, be_link);
 190         *bep = be;
 191         return (1);
 192 }
 193
 194 static void
 195 blockif_complete(struct blockif_ctxt *bc, struct blockif_elem *be)
 196 {
 197         struct blockif_elem *tbe;
 198
 199         if (be->be_status == BST_DONE || be->be_status == BST_BUSY)
 200                 TAILQ_REMOVE(&bc->bc_busyq, be, be_link);
 201         else
 202                 TAILQ_REMOVE(&bc->bc_pendq, be, be_link);
 203         TAILQ_FOREACH(tbe, &bc->bc_pendq, be_link) {
 204                 if (tbe->be_req->br_offset == be->be_block)
 205                         tbe->be_status = BST_PEND;
 206         }
 207         be->be_tid = 0;
 208         be->be_status = BST_FREE;
 209         be->be_req = NULL;
 210         TAILQ_INSERT_TAIL(&bc->bc_freeq, be, be_link);
 211 }
 212
 213 static void
 214 blockif_proc(struct blockif_ctxt *bc, struct blockif_elem *be, uint8_t *buf)
 215 {
 216         struct blockif_req *br;
 217         off_t arg[2];
 218         ssize_t clen, len, off, boff, voff;
 219         int i, err;
 220
 221         br = be->be_req;
 222         if (br->br_iovcnt <= 1)
 223                 buf = NULL;
 224         err = 0;
 225         switch (be->be_op) {
 226         case BOP_READ:
 227                 if (buf == NULL) {
 228                         if ((len = preadv(bc->bc_fd, br->br_iov, br->br_iovcnt,
 229                                    br->br_offset)) < 0)
 230                                 err = errno;
 231                         else
 232                                 br->br_resid -= len;
 233                         break;
 234                 }
 235                 i = 0;
 236                 off = voff = 0;
 237                 while (br->br_resid > 0) {
 238                         len = MIN(br->br_resid, MAXPHYS);
 239                         if (pread(bc->bc_fd, buf, len, br->br_offset +
 240                             off) < 0) {
 241                                 err = errno;
 242                                 break;
 243                         }
 244                         boff = 0;
 245                         do {
 246                                 clen = MIN(len - boff, br->br_iov[i].iov_len -
 247                                     voff);
 248                                 memcpy(br->br_iov[i].iov_base + voff,
 249                                     buf + boff, clen);
 250                                 if (clen < br->br_iov[i].iov_len - voff)
 251                                         voff += clen;
 252                                 else {
 253                                         i++;
 254                                         voff = 0;
 255                                 }
 256                                 boff += clen;
 257                         } while (boff < len);
 258                         off += len;
 259                         br->br_resid -= len;
 260                 }
 261                 break;
 262         case BOP_WRITE:
 263                 if (bc->bc_rdonly) {
 264                         err = EROFS;
 265                         break;
 266                 }
 267                 if (buf == NULL) {
 268                         if ((len = pwritev(bc->bc_fd, br->br_iov, br->br_iovcnt,
 269                                     br->br_offset)) < 0)
 270                                 err = errno;
 271                         else
 272                                 br->br_resid -= len;
 273                         break;
 274                 }
 275                 i = 0;
 276                 off = voff = 0;
 277                 while (br->br_resid > 0) {
 278                         len = MIN(br->br_resid, MAXPHYS);
 279                         boff = 0;
 280                         do {
 281                                 clen = MIN(len - boff, br->br_iov[i].iov_len -
 282                                     voff);
 283                                 memcpy(buf + boff,
 284                                     br->br_iov[i].iov_base + voff, clen);
 285                                 if (clen < br->br_iov[i].iov_len - voff)
 286                                         voff += clen;
 287                                 else {
 288                                         i++;
 289                                         voff = 0;
 290                                 }
 291                                 boff += clen;
 292                         } while (boff < len);
 293                         if (pwrite(bc->bc_fd, buf, len, br->br_offset +
 294                             off) < 0) {
 295                                 err = errno;
 296                                 break;
 297                         }
 298                         off += len;
 299                         br->br_resid -= len;
 300                 }
 301                 break;
 302         case BOP_FLUSH:
 303                 if (bc->bc_ischr) {
 304                         if (ioctl(bc->bc_fd, DIOCGFLUSH))
 305                                 err = errno;
 306                 } else if (fsync(bc->bc_fd))
 307                         err = errno;
 308                 break;
 309         case BOP_DELETE:
 310                 if (!bc->bc_candelete)
 311                         err = EOPNOTSUPP;
 312                 else if (bc->bc_rdonly)
 313                         err = EROFS;
 314                 else if (bc->bc_ischr) {
 315                         arg[0] = br->br_offset;
 316                         arg[1] = br->br_resid;
 317                         if (ioctl(bc->bc_fd, DIOCGDELETE, arg))
 318                                 err = errno;
 319                         else
 320                                 br->br_resid = 0;
 321                 } else
 322                         err = EOPNOTSUPP;
 323                 break;
 324         default:
 325                 err = EINVAL;
 326                 break;
 327         }
 328
 329         be->be_status = BST_DONE;
 330
 331         (*br->br_callback)(br, err);
 332 }
 333
 334 static void *
 335 blockif_thr(void *arg)
 336 {
 337         struct blockif_ctxt *bc;
 338         struct blockif_elem *be;
 339         pthread_t t;
 340         uint8_t *buf;
 341
 342         bc = arg;
 343         if (bc->bc_isgeom)
 344                 buf = malloc(MAXPHYS);
 345         else
 346                 buf = NULL;
 347         t = pthread_self();
 348
 349         pthread_mutex_lock(&bc->bc_mtx);
 350         for (;;) {
 351                 while (blockif_dequeue(bc, t, &be)) {
 352                         pthread_mutex_unlock(&bc->bc_mtx);
 353                         blockif_proc(bc, be, buf);
 354                         pthread_mutex_lock(&bc->bc_mtx);
 355                         blockif_complete(bc, be);
 356                 }
 357                 /* Check ctxt status here to see if exit requested */
 358                 if (bc->bc_closing)
 359                         break;
 360                 pthread_cond_wait(&bc->bc_cond, &bc->bc_mtx);
 361         }
 362         pthread_mutex_unlock(&bc->bc_mtx);
 363
 364         if (buf)
 365                 free(buf);
 366         pthread_exit(NULL);
 367         return (NULL);
 368 }
 369
 370 static void
 371 blockif_sigcont_handler(int signal, enum ev_type type, void *arg)
 372 {
 373         struct blockif_sig_elem *bse;
 374
 375         for (;;) {
 376                 /*
 377                  * Process the entire list even if not intended for
 378                  * this thread.
 379                  */
 380                 do {
 381                         bse = blockif_bse_head;
 382                         if (bse == NULL)
 383                                 return;
 384                 } while (!atomic_cmpset_ptr((uintptr_t *)&blockif_bse_head,
 385                                             (uintptr_t)bse,
 386                                             (uintptr_t)bse->bse_next));
 387
 388                 pthread_mutex_lock(&bse->bse_mtx);
 389                 bse->bse_pending = 0;
 390                 pthread_cond_signal(&bse->bse_cond);
 391                 pthread_mutex_unlock(&bse->bse_mtx);
 392         }
 393 }
 394
 395 static void
 396 blockif_init(void)
 397 {
 398         mevent_add(SIGCONT, EVF_SIGNAL, blockif_sigcont_handler, NULL);
 399         (void) signal(SIGCONT, SIG_IGN);
 400 }
 401
 402 struct blockif_ctxt *
 403 blockif_open(const char *optstr, const char *ident)
 404 {
 405         char tname[MAXCOMLEN + 1];
 406         char name[MAXPATHLEN];
 407         char *nopt, *xopts, *cp;
 408         struct blockif_ctxt *bc;
 409         struct stat sbuf;
 410         struct diocgattr_arg arg;
 411         off_t size, psectsz, psectoff;
 412         int extra, fd, i, sectsz;
 413         int nocache, sync, ro, candelete, geom, ssopt, pssopt;
 414         int nodelete;
 415
 416 #ifndef WITHOUT_CAPSICUM
 417         cap_rights_t rights;
 418         cap_ioctl_t cmds[] = { DIOCGFLUSH, DIOCGDELETE };
 419 #endif
 420
 421         pthread_once(&blockif_once, blockif_init);
 422
 423         fd = -1;
 424         ssopt = 0;
 425         nocache = 0;
 426         sync = 0;
 427         ro = 0;
 428         nodelete = 0;
 429
 430         /*
 431          * The first element in the optstring is always a pathname.
 432          * Optional elements follow
 433          */
 434         nopt = xopts = strdup(optstr);
 435         while (xopts != NULL) {
 436                 cp = strsep(&xopts, ",");
 437                 if (cp == nopt)         /* file or device pathname */
 438                         continue;
 439                 else if (!strcmp(cp, "nocache"))
 440                         nocache = 1;
 441                 else if (!strcmp(cp, "nodelete"))
 442                         nodelete = 1;
 443                 else if (!strcmp(cp, "sync") || !strcmp(cp, "direct"))
 444                         sync = 1;
 445                 else if (!strcmp(cp, "ro"))
 446                         ro = 1;
 447                 else if (sscanf(cp, "sectorsize=%d/%d", &ssopt, &pssopt) == 2)
 448                         ;
 449                 else if (sscanf(cp, "sectorsize=%d", &ssopt) == 1)
 450                         pssopt = ssopt;
 451                 else {
 452                         EPRINTLN("Invalid device option \"%s\"", cp);
 453                         goto err;
 454                 }
 455         }
 456
 457         extra = 0;
 458         if (nocache)
 459                 extra |= O_DIRECT;
 460         if (sync)
 461                 extra |= O_SYNC;
 462
 463         fd = open(nopt, (ro ? O_RDONLY : O_RDWR) | extra);
 464         if (fd < 0 && !ro) {
 465                 /* Attempt a r/w fail with a r/o open */
 466                 fd = open(nopt, O_RDONLY | extra);
 467                 ro = 1;
 468         }
 469
 470         if (fd < 0) {
 471                 warn("Could not open backing file: %s", nopt);
 472                 goto err;
 473         }
 474
 475         if (fstat(fd, &sbuf) < 0) {
 476                 warn("Could not stat backing file %s", nopt);
 477                 goto err;
 478         }
 479
 480 #ifndef WITHOUT_CAPSICUM
 481         cap_rights_init(&rights, CAP_FSYNC, CAP_IOCTL, CAP_READ, CAP_SEEK,
 482             CAP_WRITE);
 483         if (ro)
 484                 cap_rights_clear(&rights, CAP_FSYNC, CAP_WRITE);
 485
 486         if (caph_rights_limit(fd, &rights) == -1)
 487                 errx(EX_OSERR, "Unable to apply rights for sandbox");
 488 #endif
 489
 490         /*
 491          * Deal with raw devices
 492          */
 493         size = sbuf.st_size;
 494         sectsz = DEV_BSIZE;
 495         psectsz = psectoff = 0;
 496         candelete = geom = 0;
 497         if (S_ISCHR(sbuf.st_mode)) {
 498                 if (ioctl(fd, DIOCGMEDIASIZE, &size) < 0 ||
 499                     ioctl(fd, DIOCGSECTORSIZE, &sectsz)) {
 500                         perror("Could not fetch dev blk/sector size");
 501                         goto err;
 502                 }
 503                 assert(size != 0);
 504                 assert(sectsz != 0);
 505                 if (ioctl(fd, DIOCGSTRIPESIZE, &psectsz) == 0 && psectsz > 0)
 506                         ioctl(fd, DIOCGSTRIPEOFFSET, &psectoff);
 507                 strlcpy(arg.name, "GEOM::candelete", sizeof(arg.name));
 508                 arg.len = sizeof(arg.value.i);
 509                 if (nodelete == 0 && ioctl(fd, DIOCGATTR, &arg) == 0)
 510                         candelete = arg.value.i;
 511                 if (ioctl(fd, DIOCGPROVIDERNAME, name) == 0)
 512                         geom = 1;
 513         } else
 514                 psectsz = sbuf.st_blksize;
 515
 516 #ifndef WITHOUT_CAPSICUM
 517         if (caph_ioctls_limit(fd, cmds, nitems(cmds)) == -1)
 518                 errx(EX_OSERR, "Unable to apply rights for sandbox");
 519 #endif
 520
 521         if (ssopt != 0) {
 522                 if (!powerof2(ssopt) || !powerof2(pssopt) || ssopt < 512 ||
 523                     ssopt > pssopt) {
 524                         EPRINTLN("Invalid sector size %d/%d",
 525                             ssopt, pssopt);
 526                         goto err;
 527                 }
 528
 529                 /*
 530                  * Some backend drivers (e.g. cd0, ada0) require that the I/O
 531                  * size be a multiple of the device's sector size.
 532                  *
 533                  * Validate that the emulated sector size complies with this
 534                  * requirement.
 535                  */
 536                 if (S_ISCHR(sbuf.st_mode)) {
 537                         if (ssopt < sectsz || (ssopt % sectsz) != 0) {
 538                                 EPRINTLN("Sector size %d incompatible "
 539                                     "with underlying device sector size %d",
 540                                     ssopt, sectsz);
 541                                 goto err;
 542                         }
 543                 }
 544
 545                 sectsz = ssopt;
 546                 psectsz = pssopt;
 547                 psectoff = 0;
 548         }
 549
 550         bc = calloc(1, sizeof(struct blockif_ctxt));
 551         if (bc == NULL) {
 552                 perror("calloc");
 553                 goto err;
 554         }
 555
 556         bc->bc_magic = BLOCKIF_SIG;
 557         bc->bc_fd = fd;
 558         bc->bc_ischr = S_ISCHR(sbuf.st_mode);
 559         bc->bc_isgeom = geom;
 560         bc->bc_candelete = candelete;
 561         bc->bc_rdonly = ro;
 562         bc->bc_size = size;
 563         bc->bc_sectsz = sectsz;
 564         bc->bc_psectsz = psectsz;
 565         bc->bc_psectoff = psectoff;
 566         pthread_mutex_init(&bc->bc_mtx, NULL);
 567         pthread_cond_init(&bc->bc_cond, NULL);
 568         TAILQ_INIT(&bc->bc_freeq);
 569         TAILQ_INIT(&bc->bc_pendq);
 570         TAILQ_INIT(&bc->bc_busyq);
 571         for (i = 0; i < BLOCKIF_MAXREQ; i++) {
 572                 bc->bc_reqs[i].be_status = BST_FREE;
 573                 TAILQ_INSERT_HEAD(&bc->bc_freeq, &bc->bc_reqs[i], be_link);
 574         }
 575
 576         for (i = 0; i < BLOCKIF_NUMTHR; i++) {
 577                 pthread_create(&bc->bc_btid[i], NULL, blockif_thr, bc);
 578                 snprintf(tname, sizeof(tname), "blk-%s-%d", ident, i);
 579                 pthread_set_name_np(bc->bc_btid[i], tname);
 580         }
 581
 582         return (bc);
 583 err:
 584         if (fd >= 0)
 585                 close(fd);
 586         free(nopt);
 587         return (NULL);
 588 }
 589
 590 static int
 591 blockif_request(struct blockif_ctxt *bc, struct blockif_req *breq,
 592                 enum blockop op)
 593 {
 594         int err;
 595
 596         err = 0;
 597
 598         pthread_mutex_lock(&bc->bc_mtx);
 599         if (!TAILQ_EMPTY(&bc->bc_freeq)) {
 600                 /*
 601                  * Enqueue and inform the block i/o thread
 602                  * that there is work available
 603                  */
 604                 if (blockif_enqueue(bc, breq, op))
 605                         pthread_cond_signal(&bc->bc_cond);
 606         } else {
 607                 /*
 608                  * Callers are not allowed to enqueue more than
 609                  * the specified blockif queue limit. Return an
 610                  * error to indicate that the queue length has been
 611                  * exceeded.
 612                  */
 613                 err = E2BIG;
 614         }
 615         pthread_mutex_unlock(&bc->bc_mtx);
 616
 617         return (err);
 618 }
 619
 620 int
 621 blockif_read(struct blockif_ctxt *bc, struct blockif_req *breq)
 622 {
 623
 624         assert(bc->bc_magic == BLOCKIF_SIG);
 625         return (blockif_request(bc, breq, BOP_READ));
 626 }
 627
 628 int
 629 blockif_write(struct blockif_ctxt *bc, struct blockif_req *breq)
 630 {
 631
 632         assert(bc->bc_magic == BLOCKIF_SIG);
 633         return (blockif_request(bc, breq, BOP_WRITE));
 634 }
 635
 636 int
 637 blockif_flush(struct blockif_ctxt *bc, struct blockif_req *breq)
 638 {
 639
 640         assert(bc->bc_magic == BLOCKIF_SIG);
 641         return (blockif_request(bc, breq, BOP_FLUSH));
 642 }
 643
 644 int
 645 blockif_delete(struct blockif_ctxt *bc, struct blockif_req *breq)
 646 {
 647
 648         assert(bc->bc_magic == BLOCKIF_SIG);
 649         return (blockif_request(bc, breq, BOP_DELETE));
 650 }
 651
 652 int
 653 blockif_cancel(struct blockif_ctxt *bc, struct blockif_req *breq)
 654 {
 655         struct blockif_elem *be;
 656
 657         assert(bc->bc_magic == BLOCKIF_SIG);
 658
 659         pthread_mutex_lock(&bc->bc_mtx);
 660         /*
 661          * Check pending requests.
 662          */
 663         TAILQ_FOREACH(be, &bc->bc_pendq, be_link) {
 664                 if (be->be_req == breq)
 665                         break;
 666         }
 667         if (be != NULL) {
 668                 /*
 669                  * Found it.
 670                  */
 671                 blockif_complete(bc, be);
 672                 pthread_mutex_unlock(&bc->bc_mtx);
 673
 674                 return (0);
 675         }
 676
 677         /*
 678          * Check in-flight requests.
 679          */
 680         TAILQ_FOREACH(be, &bc->bc_busyq, be_link) {
 681                 if (be->be_req == breq)
 682                         break;
 683         }
 684         if (be == NULL) {
 685                 /*
 686                  * Didn't find it.
 687                  */
 688                 pthread_mutex_unlock(&bc->bc_mtx);
 689                 return (EINVAL);
 690         }
 691
 692         /*
 693          * Interrupt the processing thread to force it return
 694          * prematurely via it's normal callback path.
 695          */
 696         while (be->be_status == BST_BUSY) {
 697                 struct blockif_sig_elem bse, *old_head;
 698
 699                 pthread_mutex_init(&bse.bse_mtx, NULL);
 700                 pthread_cond_init(&bse.bse_cond, NULL);
 701
 702                 bse.bse_pending = 1;
 703
 704                 do {
 705                         old_head = blockif_bse_head;
 706                         bse.bse_next = old_head;
 707                 } while (!atomic_cmpset_ptr((uintptr_t *)&blockif_bse_head,
 708                                             (uintptr_t)old_head,
 709                                             (uintptr_t)&bse));
 710
 711                 pthread_kill(be->be_tid, SIGCONT);
 712
 713                 pthread_mutex_lock(&bse.bse_mtx);
 714                 while (bse.bse_pending)
 715                         pthread_cond_wait(&bse.bse_cond, &bse.bse_mtx);
 716                 pthread_mutex_unlock(&bse.bse_mtx);
 717         }
 718
 719         pthread_mutex_unlock(&bc->bc_mtx);
 720
 721         /*
 722          * The processing thread has been interrupted.  Since it's not
 723          * clear if the callback has been invoked yet, return EBUSY.
 724          */
 725         return (EBUSY);
 726 }
 727
 728 int
 729 blockif_close(struct blockif_ctxt *bc)
 730 {
 731         void *jval;
 732         int i;
 733
 734         assert(bc->bc_magic == BLOCKIF_SIG);
 735
 736         /*
 737          * Stop the block i/o thread
 738          */
 739         pthread_mutex_lock(&bc->bc_mtx);
 740         bc->bc_closing = 1;
 741         pthread_mutex_unlock(&bc->bc_mtx);
 742         pthread_cond_broadcast(&bc->bc_cond);
 743         for (i = 0; i < BLOCKIF_NUMTHR; i++)
 744                 pthread_join(bc->bc_btid[i], &jval);
 745
 746         /* XXX Cancel queued i/o's ??? */
 747
 748         /*
 749          * Release resources
 750          */
 751         bc->bc_magic = 0;
 752         close(bc->bc_fd);
 753         free(bc);
 754
 755         return (0);
 756 }
 757
 758 /*
 759  * Return virtual C/H/S values for a given block. Use the algorithm
 760  * outlined in the VHD specification to calculate values.
 761  */
 762 void
 763 blockif_chs(struct blockif_ctxt *bc, uint16_t *c, uint8_t *h, uint8_t *s)
 764 {
 765         off_t sectors;          /* total sectors of the block dev */
 766         off_t hcyl;             /* cylinders times heads */
 767         uint16_t secpt;         /* sectors per track */
 768         uint8_t heads;
 769
 770         assert(bc->bc_magic == BLOCKIF_SIG);
 771
 772         sectors = bc->bc_size / bc->bc_sectsz;
 773
 774         /* Clamp the size to the largest possible with CHS */
 775         if (sectors > 65535UL*16*255)
 776                 sectors = 65535UL*16*255;
 777
 778         if (sectors >= 65536UL*16*63) {
 779                 secpt = 255;
 780                 heads = 16;
 781                 hcyl = sectors / secpt;
 782         } else {
 783                 secpt = 17;
 784                 hcyl = sectors / secpt;
 785                 heads = (hcyl + 1023) / 1024;
 786
 787                 if (heads < 4)
 788                         heads = 4;
 789
 790                 if (hcyl >= (heads * 1024) || heads > 16) {
 791                         secpt = 31;
 792                         heads = 16;
 793                         hcyl = sectors / secpt;
 794                 }
 795                 if (hcyl >= (heads * 1024)) {
 796                         secpt = 63;
 797                         heads = 16;
 798                         hcyl = sectors / secpt;
 799                 }
 800         }
 801
 802         *c = hcyl / heads;
 803         *h = heads;
 804         *s = secpt;
 805 }
 806
 807 /*
 808  * Accessors
 809  */
 810 off_t
 811 blockif_size(struct blockif_ctxt *bc)
 812 {
 813
 814         assert(bc->bc_magic == BLOCKIF_SIG);
 815         return (bc->bc_size);
 816 }
 817
 818 int
 819 blockif_sectsz(struct blockif_ctxt *bc)
 820 {
 821
 822         assert(bc->bc_magic == BLOCKIF_SIG);
 823         return (bc->bc_sectsz);
 824 }
 825
 826 void
 827 blockif_psectsz(struct blockif_ctxt *bc, int *size, int *off)
 828 {
 829
 830         assert(bc->bc_magic == BLOCKIF_SIG);
 831         *size = bc->bc_psectsz;
 832         *off = bc->bc_psectoff;
 833 }
 834
 835 int
 836 blockif_queuesz(struct blockif_ctxt *bc)
 837 {
 838
 839         assert(bc->bc_magic == BLOCKIF_SIG);
 840         return (BLOCKIF_MAXREQ - 1);
 841 }
 842
 843 int
 844 blockif_is_ro(struct blockif_ctxt *bc)
 845 {
 846
 847         assert(bc->bc_magic == BLOCKIF_SIG);
 848         return (bc->bc_rdonly);
 849 }
 850
 851 int
 852 blockif_candelete(struct blockif_ctxt *bc)
 853 {
 854
 855         assert(bc->bc_magic == BLOCKIF_SIG);
 856         return (bc->bc_candelete);
 857 }