nbd.c

   1 /*
   2  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   3  *
   4  *  Network Block Device
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; under version 2 of the License.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "nbd.h"
  20 #include "block.h"
  21
  22 #include <errno.h>
  23 #include <string.h>
  24 #ifndef _WIN32
  25 #include <sys/ioctl.h>
  26 #endif
  27 #if defined(__sun__) || defined(__HAIKU__)
  28 #include <sys/ioccom.h>
  29 #endif
  30 #include <ctype.h>
  31 #include <inttypes.h>
  32
  33 #ifdef __linux__
  34 #include <linux/fs.h>
  35 #endif
  36
  37 #include "qemu_socket.h"
  38
  39 //#define DEBUG_NBD
  40
  41 #ifdef DEBUG_NBD
  42 #define TRACE(msg, ...) do { \
  43     LOG(msg, ## __VA_ARGS__); \
  44 } while(0)
  45 #else
  46 #define TRACE(msg, ...) \
  47     do { } while (0)
  48 #endif
  49
  50 #define LOG(msg, ...) do { \
  51     fprintf(stderr, "%s:%s():L%d: " msg "\n", \
  52             __FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \
  53 } while(0)
  54
  55 /* This is all part of the "official" NBD API */
  56
  57 #define NBD_REPLY_SIZE          (4 + 4 + 8)
  58 #define NBD_REQUEST_MAGIC       0x25609513
  59 #define NBD_REPLY_MAGIC         0x67446698
  60
  61 #define NBD_SET_SOCK            _IO(0xab, 0)
  62 #define NBD_SET_BLKSIZE         _IO(0xab, 1)
  63 #define NBD_SET_SIZE            _IO(0xab, 2)
  64 #define NBD_DO_IT               _IO(0xab, 3)
  65 #define NBD_CLEAR_SOCK          _IO(0xab, 4)
  66 #define NBD_CLEAR_QUE           _IO(0xab, 5)
  67 #define NBD_PRINT_DEBUG         _IO(0xab, 6)
  68 #define NBD_SET_SIZE_BLOCKS     _IO(0xab, 7)
  69 #define NBD_DISCONNECT          _IO(0xab, 8)
  70 #define NBD_SET_TIMEOUT         _IO(0xab, 9)
  71 #define NBD_SET_FLAGS           _IO(0xab, 10)
  72
  73 #define NBD_OPT_EXPORT_NAME     (1 << 0)
  74
  75 /* That's all folks */
  76
  77 #define read_sync(fd, buffer, size) nbd_wr_sync(fd, buffer, size, true)
  78 #define write_sync(fd, buffer, size) nbd_wr_sync(fd, buffer, size, false)
  79
  80 size_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
  81 {
  82     size_t offset = 0;
  83
  84     if (qemu_in_coroutine()) {
  85         if (do_read) {
  86             return qemu_co_recv(fd, buffer, size);
  87         } else {
  88             return qemu_co_send(fd, buffer, size);
  89         }
  90     }
  91
  92     while (offset < size) {
  93         ssize_t len;
  94
  95         if (do_read) {
  96             len = qemu_recv(fd, buffer + offset, size - offset, 0);
  97         } else {
  98             len = send(fd, buffer + offset, size - offset, 0);
  99         }
 100
 101         if (len == -1)
 102             errno = socket_error();
 103
 104         /* recoverable error */
 105         if (len == -1 && (errno == EAGAIN || errno == EINTR)) {
 106             continue;
 107         }
 108
 109         /* eof */
 110         if (len == 0) {
 111             break;
 112         }
 113
 114         /* unrecoverable error */
 115         if (len == -1) {
 116             return 0;
 117         }
 118
 119         offset += len;
 120     }
 121
 122     return offset;
 123 }
 124
 125 static void combine_addr(char *buf, size_t len, const char* address,
 126                          uint16_t port)
 127 {
 128     /* If the address-part contains a colon, it's an IPv6 IP so needs [] */
 129     if (strstr(address, ":")) {
 130         snprintf(buf, len, "[%s]:%u", address, port);
 131     } else {
 132         snprintf(buf, len, "%s:%u", address, port);
 133     }
 134 }
 135
 136 int tcp_socket_outgoing(const char *address, uint16_t port)
 137 {
 138     char address_and_port[128];
 139     combine_addr(address_and_port, 128, address, port);
 140     return tcp_socket_outgoing_spec(address_and_port);
 141 }
 142
 143 int tcp_socket_outgoing_spec(const char *address_and_port)
 144 {
 145     return inet_connect(address_and_port, SOCK_STREAM);
 146 }
 147
 148 int tcp_socket_incoming(const char *address, uint16_t port)
 149 {
 150     char address_and_port[128];
 151     combine_addr(address_and_port, 128, address, port);
 152     return tcp_socket_incoming_spec(address_and_port);
 153 }
 154
 155 int tcp_socket_incoming_spec(const char *address_and_port)
 156 {
 157     char *ostr  = NULL;
 158     int olen = 0;
 159     return inet_listen(address_and_port, ostr, olen, SOCK_STREAM, 0);
 160 }
 161
 162 int unix_socket_incoming(const char *path)
 163 {
 164     char *ostr = NULL;
 165     int olen = 0;
 166
 167     return unix_listen(path, ostr, olen);
 168 }
 169
 170 int unix_socket_outgoing(const char *path)
 171 {
 172     return unix_connect(path);
 173 }
 174
 175 /* Basic flow
 176
 177    Server         Client
 178
 179    Negotiate
 180                   Request
 181    Response
 182                   Request
 183    Response
 184                   ...
 185    ...
 186                   Request (type == 2)
 187 */
 188
 189 int nbd_negotiate(int csock, off_t size, uint32_t flags)
 190 {
 191     char buf[8 + 8 + 8 + 128];
 192
 193     /* Negotiate
 194         [ 0 ..   7]   passwd   ("NBDMAGIC")
 195         [ 8 ..  15]   magic    (0x00420281861253)
 196         [16 ..  23]   size
 197         [24 ..  27]   flags
 198         [28 .. 151]   reserved (0)
 199      */
 200
 201     TRACE("Beginning negotiation.");
 202     memcpy(buf, "NBDMAGIC", 8);
 203     cpu_to_be64w((uint64_t*)(buf + 8), 0x00420281861253LL);
 204     cpu_to_be64w((uint64_t*)(buf + 16), size);
 205     cpu_to_be32w((uint32_t*)(buf + 24),
 206                  flags | NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
 207                  NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
 208     memset(buf + 28, 0, 124);
 209
 210     if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
 211         LOG("write failed");
 212         errno = EINVAL;
 213         return -1;
 214     }
 215
 216     TRACE("Negotiation succeeded.");
 217
 218     return 0;
 219 }
 220
 221 int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
 222                           off_t *size, size_t *blocksize)
 223 {
 224     char buf[256];
 225     uint64_t magic, s;
 226     uint16_t tmp;
 227
 228     TRACE("Receiving negotiation.");
 229
 230     if (read_sync(csock, buf, 8) != 8) {
 231         LOG("read failed");
 232         errno = EINVAL;
 233         return -1;
 234     }
 235
 236     buf[8] = '\0';
 237     if (strlen(buf) == 0) {
 238         LOG("server connection closed");
 239         errno = EINVAL;
 240         return -1;
 241     }
 242
 243     TRACE("Magic is %c%c%c%c%c%c%c%c",
 244           qemu_isprint(buf[0]) ? buf[0] : '.',
 245           qemu_isprint(buf[1]) ? buf[1] : '.',
 246           qemu_isprint(buf[2]) ? buf[2] : '.',
 247           qemu_isprint(buf[3]) ? buf[3] : '.',
 248           qemu_isprint(buf[4]) ? buf[4] : '.',
 249           qemu_isprint(buf[5]) ? buf[5] : '.',
 250           qemu_isprint(buf[6]) ? buf[6] : '.',
 251           qemu_isprint(buf[7]) ? buf[7] : '.');
 252
 253     if (memcmp(buf, "NBDMAGIC", 8) != 0) {
 254         LOG("Invalid magic received");
 255         errno = EINVAL;
 256         return -1;
 257     }
 258
 259     if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
 260         LOG("read failed");
 261         errno = EINVAL;
 262         return -1;
 263     }
 264     magic = be64_to_cpu(magic);
 265     TRACE("Magic is 0x%" PRIx64, magic);
 266
 267     if (name) {
 268         uint32_t reserved = 0;
 269         uint32_t opt;
 270         uint32_t namesize;
 271
 272         TRACE("Checking magic (opts_magic)");
 273         if (magic != 0x49484156454F5054LL) {
 274             LOG("Bad magic received");
 275             errno = EINVAL;
 276             return -1;
 277         }
 278         if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
 279             LOG("flags read failed");
 280             errno = EINVAL;
 281             return -1;
 282         }
 283         *flags = be16_to_cpu(tmp) << 16;
 284         /* reserved for future use */
 285         if (write_sync(csock, &reserved, sizeof(reserved)) !=
 286             sizeof(reserved)) {
 287             LOG("write failed (reserved)");
 288             errno = EINVAL;
 289             return -1;
 290         }
 291         /* write the export name */
 292         magic = cpu_to_be64(magic);
 293         if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
 294             LOG("write failed (magic)");
 295             errno = EINVAL;
 296             return -1;
 297         }
 298         opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
 299         if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
 300             LOG("write failed (opt)");
 301             errno = EINVAL;
 302             return -1;
 303         }
 304         namesize = cpu_to_be32(strlen(name));
 305         if (write_sync(csock, &namesize, sizeof(namesize)) !=
 306             sizeof(namesize)) {
 307             LOG("write failed (namesize)");
 308             errno = EINVAL;
 309             return -1;
 310         }
 311         if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) {
 312             LOG("write failed (name)");
 313             errno = EINVAL;
 314             return -1;
 315         }
 316     } else {
 317         TRACE("Checking magic (cli_magic)");
 318
 319         if (magic != 0x00420281861253LL) {
 320             LOG("Bad magic received");
 321             errno = EINVAL;
 322             return -1;
 323         }
 324     }
 325
 326     if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) {
 327         LOG("read failed");
 328         errno = EINVAL;
 329         return -1;
 330     }
 331     *size = be64_to_cpu(s);
 332     *blocksize = 1024;
 333     TRACE("Size is %" PRIu64, *size);
 334
 335     if (!name) {
 336         if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) {
 337             LOG("read failed (flags)");
 338             errno = EINVAL;
 339             return -1;
 340         }
 341         *flags = be32_to_cpup(flags);
 342     } else {
 343         if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
 344             LOG("read failed (tmp)");
 345             errno = EINVAL;
 346             return -1;
 347         }
 348         *flags |= be32_to_cpu(tmp);
 349     }
 350     if (read_sync(csock, &buf, 124) != 124) {
 351         LOG("read failed (buf)");
 352         errno = EINVAL;
 353         return -1;
 354     }
 355         return 0;
 356 }
 357
 358 #ifdef __linux__
 359 int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
 360 {
 361     TRACE("Setting NBD socket");
 362
 363     if (ioctl(fd, NBD_SET_SOCK, csock) == -1) {
 364         int serrno = errno;
 365         LOG("Failed to set NBD socket");
 366         errno = serrno;
 367         return -1;
 368     }
 369
 370     TRACE("Setting block size to %lu", (unsigned long)blocksize);
 371
 372     if (ioctl(fd, NBD_SET_BLKSIZE, blocksize) == -1) {
 373         int serrno = errno;
 374         LOG("Failed setting NBD block size");
 375         errno = serrno;
 376         return -1;
 377     }
 378
 379         TRACE("Setting size to %zd block(s)", (size_t)(size / blocksize));
 380
 381     if (ioctl(fd, NBD_SET_SIZE_BLOCKS, size / blocksize) == -1) {
 382         int serrno = errno;
 383         LOG("Failed setting size (in blocks)");
 384         errno = serrno;
 385         return -1;
 386     }
 387
 388     if (flags & NBD_FLAG_READ_ONLY) {
 389         int read_only = 1;
 390         TRACE("Setting readonly attribute");
 391
 392         if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
 393             int serrno = errno;
 394             LOG("Failed setting read-only attribute");
 395             errno = serrno;
 396             return -1;
 397         }
 398     }
 399
 400     if (ioctl(fd, NBD_SET_FLAGS, flags) < 0
 401         && errno != ENOTTY) {
 402         int serrno = errno;
 403         LOG("Failed setting flags");
 404         errno = serrno;
 405         return -1;
 406     }
 407
 408     TRACE("Negotiation ended");
 409
 410     return 0;
 411 }
 412
 413 int nbd_disconnect(int fd)
 414 {
 415     ioctl(fd, NBD_CLEAR_QUE);
 416     ioctl(fd, NBD_DISCONNECT);
 417     ioctl(fd, NBD_CLEAR_SOCK);
 418     return 0;
 419 }
 420
 421 int nbd_client(int fd)
 422 {
 423     int ret;
 424     int serrno;
 425
 426     TRACE("Doing NBD loop");
 427
 428     ret = ioctl(fd, NBD_DO_IT);
 429     if (ret == -1 && errno == EPIPE) {
 430         /* NBD_DO_IT normally returns EPIPE when someone has disconnected
 431          * the socket via NBD_DISCONNECT.  We do not want to return 1 in
 432          * that case.
 433          */
 434         ret = 0;
 435     }
 436     serrno = errno;
 437
 438     TRACE("NBD loop returned %d: %s", ret, strerror(serrno));
 439
 440     TRACE("Clearing NBD queue");
 441     ioctl(fd, NBD_CLEAR_QUE);
 442
 443     TRACE("Clearing NBD socket");
 444     ioctl(fd, NBD_CLEAR_SOCK);
 445
 446     errno = serrno;
 447     return ret;
 448 }
 449 #else
 450 int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
 451 {
 452     errno = ENOTSUP;
 453     return -1;
 454 }
 455
 456 int nbd_disconnect(int fd)
 457 {
 458     errno = ENOTSUP;
 459     return -1;
 460 }
 461
 462 int nbd_client(int fd)
 463 {
 464     errno = ENOTSUP;
 465     return -1;
 466 }
 467 #endif
 468
 469 int nbd_send_request(int csock, struct nbd_request *request)
 470 {
 471     uint8_t buf[4 + 4 + 8 + 8 + 4];
 472
 473     cpu_to_be32w((uint32_t*)buf, NBD_REQUEST_MAGIC);
 474     cpu_to_be32w((uint32_t*)(buf + 4), request->type);
 475     cpu_to_be64w((uint64_t*)(buf + 8), request->handle);
 476     cpu_to_be64w((uint64_t*)(buf + 16), request->from);
 477     cpu_to_be32w((uint32_t*)(buf + 24), request->len);
 478
 479     TRACE("Sending request to client: "
 480           "{ .from = %" PRIu64", .len = %u, .handle = %" PRIu64", .type=%i}",
 481           request->from, request->len, request->handle, request->type);
 482
 483     if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
 484         LOG("writing to socket failed");
 485         errno = EINVAL;
 486         return -1;
 487     }
 488     return 0;
 489 }
 490
 491 static int nbd_receive_request(int csock, struct nbd_request *request)
 492 {
 493     uint8_t buf[4 + 4 + 8 + 8 + 4];
 494     uint32_t magic;
 495
 496     if (read_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
 497         LOG("read failed");
 498         errno = EINVAL;
 499         return -1;
 500     }
 501
 502     /* Request
 503        [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
 504        [ 4 ..  7]   type    (0 == READ, 1 == WRITE)
 505        [ 8 .. 15]   handle
 506        [16 .. 23]   from
 507        [24 .. 27]   len
 508      */
 509
 510     magic = be32_to_cpup((uint32_t*)buf);
 511     request->type  = be32_to_cpup((uint32_t*)(buf + 4));
 512     request->handle = be64_to_cpup((uint64_t*)(buf + 8));
 513     request->from  = be64_to_cpup((uint64_t*)(buf + 16));
 514     request->len   = be32_to_cpup((uint32_t*)(buf + 24));
 515
 516     TRACE("Got request: "
 517           "{ magic = 0x%x, .type = %d, from = %" PRIu64" , len = %u }",
 518           magic, request->type, request->from, request->len);
 519
 520     if (magic != NBD_REQUEST_MAGIC) {
 521         LOG("invalid magic (got 0x%x)", magic);
 522         errno = EINVAL;
 523         return -1;
 524     }
 525     return 0;
 526 }
 527
 528 int nbd_receive_reply(int csock, struct nbd_reply *reply)
 529 {
 530     uint8_t buf[NBD_REPLY_SIZE];
 531     uint32_t magic;
 532
 533     memset(buf, 0xAA, sizeof(buf));
 534
 535     if (read_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
 536         LOG("read failed");
 537         errno = EINVAL;
 538         return -1;
 539     }
 540
 541     /* Reply
 542        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 543        [ 4 ..  7]    error   (0 == no error)
 544        [ 7 .. 15]    handle
 545      */
 546
 547     magic = be32_to_cpup((uint32_t*)buf);
 548     reply->error  = be32_to_cpup((uint32_t*)(buf + 4));
 549     reply->handle = be64_to_cpup((uint64_t*)(buf + 8));
 550
 551     TRACE("Got reply: "
 552           "{ magic = 0x%x, .error = %d, handle = %" PRIu64" }",
 553           magic, reply->error, reply->handle);
 554
 555     if (magic != NBD_REPLY_MAGIC) {
 556         LOG("invalid magic (got 0x%x)", magic);
 557         errno = EINVAL;
 558         return -1;
 559     }
 560     return 0;
 561 }
 562
 563 static int nbd_send_reply(int csock, struct nbd_reply *reply)
 564 {
 565     uint8_t buf[4 + 4 + 8];
 566
 567     /* Reply
 568        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 569        [ 4 ..  7]    error   (0 == no error)
 570        [ 7 .. 15]    handle
 571      */
 572     cpu_to_be32w((uint32_t*)buf, NBD_REPLY_MAGIC);
 573     cpu_to_be32w((uint32_t*)(buf + 4), reply->error);
 574     cpu_to_be64w((uint64_t*)(buf + 8), reply->handle);
 575
 576     TRACE("Sending response to client");
 577
 578     if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
 579         LOG("writing to socket failed");
 580         errno = EINVAL;
 581         return -1;
 582     }
 583     return 0;
 584 }
 585
 586 static int nbd_do_send_reply(int csock, struct nbd_reply *reply,
 587                              uint8_t *data, int len)
 588 {
 589     int rc, ret;
 590
 591     if (!len) {
 592         rc = nbd_send_reply(csock, reply);
 593         if (rc == -1) {
 594             rc = -errno;
 595         }
 596     } else {
 597         socket_set_cork(csock, 1);
 598         rc = nbd_send_reply(csock, reply);
 599         if (rc != -1) {
 600             ret = write_sync(csock, data, len);
 601             if (ret != len) {
 602                 errno = EIO;
 603                 rc = -1;
 604             }
 605         }
 606         if (rc == -1) {
 607             rc = -errno;
 608         }
 609         socket_set_cork(csock, 0);
 610     }
 611     return rc;
 612 }
 613
 614 int nbd_trip(BlockDriverState *bs, int csock, off_t size,
 615              uint64_t dev_offset, uint32_t nbdflags,
 616              uint8_t *data)
 617 {
 618     struct nbd_request request;
 619     struct nbd_reply reply;
 620     int ret;
 621
 622     TRACE("Reading request.");
 623
 624     if (nbd_receive_request(csock, &request) == -1)
 625         return -1;
 626
 627     if (request.len > NBD_BUFFER_SIZE) {
 628         LOG("len (%u) is larger than max len (%u)",
 629             request.len, NBD_BUFFER_SIZE);
 630         errno = EINVAL;
 631         return -1;
 632     }
 633
 634     if ((request.from + request.len) < request.from) {
 635         LOG("integer overflow detected! "
 636             "you're probably being attacked");
 637         errno = EINVAL;
 638         return -1;
 639     }
 640
 641     if ((request.from + request.len) > size) {
 642             LOG("From: %" PRIu64 ", Len: %u, Size: %" PRIu64
 643             ", Offset: %" PRIu64 "\n",
 644                     request.from, request.len, (uint64_t)size, dev_offset);
 645         LOG("requested operation past EOF--bad client?");
 646         errno = EINVAL;
 647         return -1;
 648     }
 649
 650     TRACE("Decoding type");
 651
 652     reply.handle = request.handle;
 653     reply.error = 0;
 654
 655     switch (request.type & NBD_CMD_MASK_COMMAND) {
 656     case NBD_CMD_READ:
 657         TRACE("Request type is READ");
 658
 659         ret = bdrv_read(bs, (request.from + dev_offset) / 512,
 660                         data, request.len / 512);
 661         if (ret < 0) {
 662             LOG("reading from file failed");
 663             reply.error = -ret;
 664             request.len = 0;
 665         }
 666
 667         TRACE("Read %u byte(s)", request.len);
 668         if (nbd_do_send_reply(csock, &reply, data, request.len) < 0)
 669             return -1;
 670         break;
 671     case NBD_CMD_WRITE:
 672         TRACE("Request type is WRITE");
 673
 674         TRACE("Reading %u byte(s)", request.len);
 675
 676         if (read_sync(csock, data, request.len) != request.len) {
 677             LOG("reading from socket failed");
 678             errno = EINVAL;
 679             return -1;
 680         }
 681
 682         if (nbdflags & NBD_FLAG_READ_ONLY) {
 683             TRACE("Server is read-only, return error");
 684             reply.error = 1;
 685         } else {
 686             TRACE("Writing to device");
 687
 688             ret = bdrv_write(bs, (request.from + dev_offset) / 512,
 689                              data, request.len / 512);
 690             if (ret < 0) {
 691                 LOG("writing to file failed");
 692                 reply.error = -ret;
 693                 request.len = 0;
 694             }
 695
 696             if (request.type & NBD_CMD_FLAG_FUA) {
 697                 ret = bdrv_flush(bs);
 698                 if (ret < 0) {
 699                     LOG("flush failed");
 700                     reply.error = -ret;
 701                 }
 702             }
 703         }
 704
 705         if (nbd_do_send_reply(csock, &reply, NULL, 0) < 0)
 706             return -1;
 707         break;
 708     case NBD_CMD_DISC:
 709         TRACE("Request type is DISCONNECT");
 710         errno = 0;
 711         return 1;
 712     case NBD_CMD_FLUSH:
 713         TRACE("Request type is FLUSH");
 714
 715         ret = bdrv_flush(bs);
 716         if (ret < 0) {
 717             LOG("flush failed");
 718             reply.error = -ret;
 719         }
 720
 721         if (nbd_do_send_reply(csock, &reply, NULL, 0) < 0)
 722             return -1;
 723         break;
 724     case NBD_CMD_TRIM:
 725         TRACE("Request type is TRIM");
 726         ret = bdrv_discard(bs, (request.from + dev_offset) / 512,
 727                            request.len / 512);
 728         if (ret < 0) {
 729             LOG("discard failed");
 730             reply.error = -ret;
 731         }
 732         if (nbd_do_send_reply(csock, &reply, NULL, 0) < 0)
 733             return -1;
 734         break;
 735     default:
 736         LOG("invalid request type (%u) received", request.type);
 737         errno = EINVAL;
 738         return -1;
 739     }
 740
 741     TRACE("Request/Reply complete");
 742
 743     return 0;
 744 }