block/rbd.c

   1 /*
   2  * QEMU Block driver for RADOS (Ceph)
   3  *
   4  * Copyright (C) 2010-2011 Christian Brunner <chb@muc.de>,
   5  *                         Josh Durgin <josh.durgin@dreamhost.com>
   6  *
   7  * This work is licensed under the terms of the GNU GPL, version 2.  See
   8  * the COPYING file in the top-level directory.
   9  *
  10  */
  11
  12 #include <inttypes.h>
  13
  14 #include "qemu-common.h"
  15 #include "qemu-error.h"
  16 #include "block_int.h"
  17
  18 #include <rbd/librbd.h>
  19
  20 /*
  21  * When specifying the image filename use:
  22  *
  23  * rbd:poolname/devicename[@snapshotname][:option1=value1[:option2=value2...]]
  24  *
  25  * poolname must be the name of an existing rados pool.
  26  *
  27  * devicename is the name of the rbd image.
  28  *
  29  * Each option given is used to configure rados, and may be any valid
  30  * Ceph option, "id", or "conf".
  31  *
  32  * The "id" option indicates what user we should authenticate as to
  33  * the Ceph cluster.  If it is excluded we will use the Ceph default
  34  * (normally 'admin').
  35  *
  36  * The "conf" option specifies a Ceph configuration file to read.  If
  37  * it is not specified, we will read from the default Ceph locations
  38  * (e.g., /etc/ceph/ceph.conf).  To avoid reading _any_ configuration
  39  * file, specify conf=/dev/null.
  40  *
  41  * Configuration values containing :, @, or = can be escaped with a
  42  * leading "\".
  43  */
  44
  45 #define OBJ_MAX_SIZE (1UL << OBJ_DEFAULT_OBJ_ORDER)
  46
  47 #define RBD_MAX_CONF_NAME_SIZE 128
  48 #define RBD_MAX_CONF_VAL_SIZE 512
  49 #define RBD_MAX_CONF_SIZE 1024
  50 #define RBD_MAX_POOL_NAME_SIZE 128
  51 #define RBD_MAX_SNAP_NAME_SIZE 128
  52 #define RBD_MAX_SNAPS 100
  53
  54 typedef struct RBDAIOCB {
  55     BlockDriverAIOCB common;
  56     QEMUBH *bh;
  57     int ret;
  58     QEMUIOVector *qiov;
  59     char *bounce;
  60     int write;
  61     int64_t sector_num;
  62     int error;
  63     struct BDRVRBDState *s;
  64     int cancelled;
  65 } RBDAIOCB;
  66
  67 typedef struct RADOSCB {
  68     int rcbid;
  69     RBDAIOCB *acb;
  70     struct BDRVRBDState *s;
  71     int done;
  72     int64_t size;
  73     char *buf;
  74     int ret;
  75 } RADOSCB;
  76
  77 #define RBD_FD_READ 0
  78 #define RBD_FD_WRITE 1
  79
  80 typedef struct BDRVRBDState {
  81     int fds[2];
  82     rados_t cluster;
  83     rados_ioctx_t io_ctx;
  84     rbd_image_t image;
  85     char name[RBD_MAX_IMAGE_NAME_SIZE];
  86     int qemu_aio_count;
  87     char *snap;
  88     int event_reader_pos;
  89     RADOSCB *event_rcb;
  90 } BDRVRBDState;
  91
  92 static void rbd_aio_bh_cb(void *opaque);
  93
  94 static int qemu_rbd_next_tok(char *dst, int dst_len,
  95                              char *src, char delim,
  96                              const char *name,
  97                              char **p)
  98 {
  99     int l;
 100     char *end;
 101
 102     *p = NULL;
 103
 104     if (delim != '\0') {
 105         for (end = src; *end; ++end) {
 106             if (*end == delim) {
 107                 break;
 108             }
 109             if (*end == '\\' && end[1] != '\0') {
 110                 end++;
 111             }
 112         }
 113         if (*end == delim) {
 114             *p = end + 1;
 115             *end = '\0';
 116         }
 117     }
 118     l = strlen(src);
 119     if (l >= dst_len) {
 120         error_report("%s too long", name);
 121         return -EINVAL;
 122     } else if (l == 0) {
 123         error_report("%s too short", name);
 124         return -EINVAL;
 125     }
 126
 127     pstrcpy(dst, dst_len, src);
 128
 129     return 0;
 130 }
 131
 132 static void qemu_rbd_unescape(char *src)
 133 {
 134     char *p;
 135
 136     for (p = src; *src; ++src, ++p) {
 137         if (*src == '\\' && src[1] != '\0') {
 138             src++;
 139         }
 140         *p = *src;
 141     }
 142     *p = '\0';
 143 }
 144
 145 static int qemu_rbd_parsename(const char *filename,
 146                               char *pool, int pool_len,
 147                               char *snap, int snap_len,
 148                               char *name, int name_len,
 149                               char *conf, int conf_len)
 150 {
 151     const char *start;
 152     char *p, *buf;
 153     int ret;
 154
 155     if (!strstart(filename, "rbd:", &start)) {
 156         return -EINVAL;
 157     }
 158
 159     buf = g_strdup(start);
 160     p = buf;
 161     *snap = '\0';
 162     *conf = '\0';
 163
 164     ret = qemu_rbd_next_tok(pool, pool_len, p, '/', "pool name", &p);
 165     if (ret < 0 || !p) {
 166         ret = -EINVAL;
 167         goto done;
 168     }
 169     qemu_rbd_unescape(pool);
 170
 171     if (strchr(p, '@')) {
 172         ret = qemu_rbd_next_tok(name, name_len, p, '@', "object name", &p);
 173         if (ret < 0) {
 174             goto done;
 175         }
 176         ret = qemu_rbd_next_tok(snap, snap_len, p, ':', "snap name", &p);
 177         qemu_rbd_unescape(snap);
 178     } else {
 179         ret = qemu_rbd_next_tok(name, name_len, p, ':', "object name", &p);
 180     }
 181     qemu_rbd_unescape(name);
 182     if (ret < 0 || !p) {
 183         goto done;
 184     }
 185
 186     ret = qemu_rbd_next_tok(conf, conf_len, p, '\0', "configuration", &p);
 187
 188 done:
 189     g_free(buf);
 190     return ret;
 191 }
 192
 193 static char *qemu_rbd_parse_clientname(const char *conf, char *clientname)
 194 {
 195     const char *p = conf;
 196
 197     while (*p) {
 198         int len;
 199         const char *end = strchr(p, ':');
 200
 201         if (end) {
 202             len = end - p;
 203         } else {
 204             len = strlen(p);
 205         }
 206
 207         if (strncmp(p, "id=", 3) == 0) {
 208             len -= 3;
 209             strncpy(clientname, p + 3, len);
 210             clientname[len] = '\0';
 211             return clientname;
 212         }
 213         if (end == NULL) {
 214             break;
 215         }
 216         p = end + 1;
 217     }
 218     return NULL;
 219 }
 220
 221 static int qemu_rbd_set_conf(rados_t cluster, const char *conf)
 222 {
 223     char *p, *buf;
 224     char name[RBD_MAX_CONF_NAME_SIZE];
 225     char value[RBD_MAX_CONF_VAL_SIZE];
 226     int ret = 0;
 227
 228     buf = g_strdup(conf);
 229     p = buf;
 230
 231     while (p) {
 232         ret = qemu_rbd_next_tok(name, sizeof(name), p,
 233                                 '=', "conf option name", &p);
 234         if (ret < 0) {
 235             break;
 236         }
 237         qemu_rbd_unescape(name);
 238
 239         if (!p) {
 240             error_report("conf option %s has no value", name);
 241             ret = -EINVAL;
 242             break;
 243         }
 244
 245         ret = qemu_rbd_next_tok(value, sizeof(value), p,
 246                                 ':', "conf option value", &p);
 247         if (ret < 0) {
 248             break;
 249         }
 250         qemu_rbd_unescape(value);
 251
 252         if (strcmp(name, "conf") == 0) {
 253             ret = rados_conf_read_file(cluster, value);
 254             if (ret < 0) {
 255                 error_report("error reading conf file %s", value);
 256                 break;
 257             }
 258         } else if (strcmp(name, "id") == 0) {
 259             /* ignore, this is parsed by qemu_rbd_parse_clientname() */
 260         } else {
 261             ret = rados_conf_set(cluster, name, value);
 262             if (ret < 0) {
 263                 error_report("invalid conf option %s", name);
 264                 ret = -EINVAL;
 265                 break;
 266             }
 267         }
 268     }
 269
 270     g_free(buf);
 271     return ret;
 272 }
 273
 274 static int qemu_rbd_create(const char *filename, QEMUOptionParameter *options)
 275 {
 276     int64_t bytes = 0;
 277     int64_t objsize;
 278     int obj_order = 0;
 279     char pool[RBD_MAX_POOL_NAME_SIZE];
 280     char name[RBD_MAX_IMAGE_NAME_SIZE];
 281     char snap_buf[RBD_MAX_SNAP_NAME_SIZE];
 282     char conf[RBD_MAX_CONF_SIZE];
 283     char clientname_buf[RBD_MAX_CONF_SIZE];
 284     char *clientname;
 285     rados_t cluster;
 286     rados_ioctx_t io_ctx;
 287     int ret;
 288
 289     if (qemu_rbd_parsename(filename, pool, sizeof(pool),
 290                            snap_buf, sizeof(snap_buf),
 291                            name, sizeof(name),
 292                            conf, sizeof(conf)) < 0) {
 293         return -EINVAL;
 294     }
 295
 296     /* Read out options */
 297     while (options && options->name) {
 298         if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
 299             bytes = options->value.n;
 300         } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
 301             if (options->value.n) {
 302                 objsize = options->value.n;
 303                 if ((objsize - 1) & objsize) {    /* not a power of 2? */
 304                     error_report("obj size needs to be power of 2");
 305                     return -EINVAL;
 306                 }
 307                 if (objsize < 4096) {
 308                     error_report("obj size too small");
 309                     return -EINVAL;
 310                 }
 311                 obj_order = ffs(objsize) - 1;
 312             }
 313         }
 314         options++;
 315     }
 316
 317     clientname = qemu_rbd_parse_clientname(conf, clientname_buf);
 318     if (rados_create(&cluster, clientname) < 0) {
 319         error_report("error initializing");
 320         return -EIO;
 321     }
 322
 323     if (strstr(conf, "conf=") == NULL) {
 324         /* try default location, but ignore failure */
 325         rados_conf_read_file(cluster, NULL);
 326     }
 327
 328     if (conf[0] != '\0' &&
 329         qemu_rbd_set_conf(cluster, conf) < 0) {
 330         error_report("error setting config options");
 331         rados_shutdown(cluster);
 332         return -EIO;
 333     }
 334
 335     if (rados_connect(cluster) < 0) {
 336         error_report("error connecting");
 337         rados_shutdown(cluster);
 338         return -EIO;
 339     }
 340
 341     if (rados_ioctx_create(cluster, pool, &io_ctx) < 0) {
 342         error_report("error opening pool %s", pool);
 343         rados_shutdown(cluster);
 344         return -EIO;
 345     }
 346
 347     ret = rbd_create(io_ctx, name, bytes, &obj_order);
 348     rados_ioctx_destroy(io_ctx);
 349     rados_shutdown(cluster);
 350
 351     return ret;
 352 }
 353
 354 /*
 355  * This aio completion is being called from qemu_rbd_aio_event_reader()
 356  * and runs in qemu context. It schedules a bh, but just in case the aio
 357  * was not cancelled before.
 358  */
 359 static void qemu_rbd_complete_aio(RADOSCB *rcb)
 360 {
 361     RBDAIOCB *acb = rcb->acb;
 362     int64_t r;
 363
 364     if (acb->cancelled) {
 365         qemu_vfree(acb->bounce);
 366         qemu_aio_release(acb);
 367         goto done;
 368     }
 369
 370     r = rcb->ret;
 371
 372     if (acb->write) {
 373         if (r < 0) {
 374             acb->ret = r;
 375             acb->error = 1;
 376         } else if (!acb->error) {
 377             acb->ret = rcb->size;
 378         }
 379     } else {
 380         if (r < 0) {
 381             memset(rcb->buf, 0, rcb->size);
 382             acb->ret = r;
 383             acb->error = 1;
 384         } else if (r < rcb->size) {
 385             memset(rcb->buf + r, 0, rcb->size - r);
 386             if (!acb->error) {
 387                 acb->ret = rcb->size;
 388             }
 389         } else if (!acb->error) {
 390             acb->ret = r;
 391         }
 392     }
 393     /* Note that acb->bh can be NULL in case where the aio was cancelled */
 394     acb->bh = qemu_bh_new(rbd_aio_bh_cb, acb);
 395     qemu_bh_schedule(acb->bh);
 396 done:
 397     g_free(rcb);
 398 }
 399
 400 /*
 401  * aio fd read handler. It runs in the qemu context and calls the
 402  * completion handling of completed rados aio operations.
 403  */
 404 static void qemu_rbd_aio_event_reader(void *opaque)
 405 {
 406     BDRVRBDState *s = opaque;
 407
 408     ssize_t ret;
 409
 410     do {
 411         char *p = (char *)&s->event_rcb;
 412
 413         /* now read the rcb pointer that was sent from a non qemu thread */
 414         ret = read(s->fds[RBD_FD_READ], p + s->event_reader_pos,
 415                    sizeof(s->event_rcb) - s->event_reader_pos);
 416         if (ret > 0) {
 417             s->event_reader_pos += ret;
 418             if (s->event_reader_pos == sizeof(s->event_rcb)) {
 419                 s->event_reader_pos = 0;
 420                 qemu_rbd_complete_aio(s->event_rcb);
 421                 s->qemu_aio_count--;
 422             }
 423         }
 424     } while (ret < 0 && errno == EINTR);
 425 }
 426
 427 static int qemu_rbd_aio_flush_cb(void *opaque)
 428 {
 429     BDRVRBDState *s = opaque;
 430
 431     return (s->qemu_aio_count > 0);
 432 }
 433
 434 static int qemu_rbd_open(BlockDriverState *bs, const char *filename, int flags)
 435 {
 436     BDRVRBDState *s = bs->opaque;
 437     char pool[RBD_MAX_POOL_NAME_SIZE];
 438     char snap_buf[RBD_MAX_SNAP_NAME_SIZE];
 439     char conf[RBD_MAX_CONF_SIZE];
 440     char clientname_buf[RBD_MAX_CONF_SIZE];
 441     char *clientname;
 442     int r;
 443
 444     if (qemu_rbd_parsename(filename, pool, sizeof(pool),
 445                            snap_buf, sizeof(snap_buf),
 446                            s->name, sizeof(s->name),
 447                            conf, sizeof(conf)) < 0) {
 448         return -EINVAL;
 449     }
 450
 451     clientname = qemu_rbd_parse_clientname(conf, clientname_buf);
 452     r = rados_create(&s->cluster, clientname);
 453     if (r < 0) {
 454         error_report("error initializing");
 455         return r;
 456     }
 457
 458     s->snap = NULL;
 459     if (snap_buf[0] != '\0') {
 460         s->snap = g_strdup(snap_buf);
 461     }
 462
 463     if (strstr(conf, "conf=") == NULL) {
 464         /* try default location, but ignore failure */
 465         rados_conf_read_file(s->cluster, NULL);
 466     }
 467
 468     if (conf[0] != '\0') {
 469         r = qemu_rbd_set_conf(s->cluster, conf);
 470         if (r < 0) {
 471             error_report("error setting config options");
 472             goto failed_shutdown;
 473         }
 474     }
 475
 476     r = rados_connect(s->cluster);
 477     if (r < 0) {
 478         error_report("error connecting");
 479         goto failed_shutdown;
 480     }
 481
 482     r = rados_ioctx_create(s->cluster, pool, &s->io_ctx);
 483     if (r < 0) {
 484         error_report("error opening pool %s", pool);
 485         goto failed_shutdown;
 486     }
 487
 488     r = rbd_open(s->io_ctx, s->name, &s->image, s->snap);
 489     if (r < 0) {
 490         error_report("error reading header from %s", s->name);
 491         goto failed_open;
 492     }
 493
 494     bs->read_only = (s->snap != NULL);
 495
 496     s->event_reader_pos = 0;
 497     r = qemu_pipe(s->fds);
 498     if (r < 0) {
 499         error_report("error opening eventfd");
 500         goto failed;
 501     }
 502     fcntl(s->fds[0], F_SETFL, O_NONBLOCK);
 503     fcntl(s->fds[1], F_SETFL, O_NONBLOCK);
 504     qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], qemu_rbd_aio_event_reader,
 505                             NULL, qemu_rbd_aio_flush_cb, NULL, s);
 506
 507
 508     return 0;
 509
 510 failed:
 511     rbd_close(s->image);
 512 failed_open:
 513     rados_ioctx_destroy(s->io_ctx);
 514 failed_shutdown:
 515     rados_shutdown(s->cluster);
 516     g_free(s->snap);
 517     return r;
 518 }
 519
 520 static void qemu_rbd_close(BlockDriverState *bs)
 521 {
 522     BDRVRBDState *s = bs->opaque;
 523
 524     close(s->fds[0]);
 525     close(s->fds[1]);
 526     qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], NULL , NULL, NULL, NULL,
 527         NULL);
 528
 529     rbd_close(s->image);
 530     rados_ioctx_destroy(s->io_ctx);
 531     g_free(s->snap);
 532     rados_shutdown(s->cluster);
 533 }
 534
 535 /*
 536  * Cancel aio. Since we don't reference acb in a non qemu threads,
 537  * it is safe to access it here.
 538  */
 539 static void qemu_rbd_aio_cancel(BlockDriverAIOCB *blockacb)
 540 {
 541     RBDAIOCB *acb = (RBDAIOCB *) blockacb;
 542     acb->cancelled = 1;
 543 }
 544
 545 static AIOPool rbd_aio_pool = {
 546     .aiocb_size = sizeof(RBDAIOCB),
 547     .cancel = qemu_rbd_aio_cancel,
 548 };
 549
 550 static int qemu_rbd_send_pipe(BDRVRBDState *s, RADOSCB *rcb)
 551 {
 552     int ret = 0;
 553     while (1) {
 554         fd_set wfd;
 555         int fd = s->fds[RBD_FD_WRITE];
 556
 557         /* send the op pointer to the qemu thread that is responsible
 558            for the aio/op completion. Must do it in a qemu thread context */
 559         ret = write(fd, (void *)&rcb, sizeof(rcb));
 560         if (ret >= 0) {
 561             break;
 562         }
 563         if (errno == EINTR) {
 564             continue;
 565         }
 566         if (errno != EAGAIN) {
 567             break;
 568         }
 569
 570         FD_ZERO(&wfd);
 571         FD_SET(fd, &wfd);
 572         do {
 573             ret = select(fd + 1, NULL, &wfd, NULL, NULL);
 574         } while (ret < 0 && errno == EINTR);
 575     }
 576
 577     return ret;
 578 }
 579
 580 /*
 581  * This is the callback function for rbd_aio_read and _write
 582  *
 583  * Note: this function is being called from a non qemu thread so
 584  * we need to be careful about what we do here. Generally we only
 585  * write to the block notification pipe, and do the rest of the
 586  * io completion handling from qemu_rbd_aio_event_reader() which
 587  * runs in a qemu context.
 588  */
 589 static void rbd_finish_aiocb(rbd_completion_t c, RADOSCB *rcb)
 590 {
 591     int ret;
 592     rcb->ret = rbd_aio_get_return_value(c);
 593     rbd_aio_release(c);
 594     ret = qemu_rbd_send_pipe(rcb->s, rcb);
 595     if (ret < 0) {
 596         error_report("failed writing to acb->s->fds");
 597         g_free(rcb);
 598     }
 599 }
 600
 601 /* Callback when all queued rbd_aio requests are complete */
 602
 603 static void rbd_aio_bh_cb(void *opaque)
 604 {
 605     RBDAIOCB *acb = opaque;
 606
 607     if (!acb->write) {
 608         qemu_iovec_from_buffer(acb->qiov, acb->bounce, acb->qiov->size);
 609     }
 610     qemu_vfree(acb->bounce);
 611     acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));
 612     qemu_bh_delete(acb->bh);
 613     acb->bh = NULL;
 614
 615     qemu_aio_release(acb);
 616 }
 617
 618 static BlockDriverAIOCB *rbd_aio_rw_vector(BlockDriverState *bs,
 619                                            int64_t sector_num,
 620                                            QEMUIOVector *qiov,
 621                                            int nb_sectors,
 622                                            BlockDriverCompletionFunc *cb,
 623                                            void *opaque, int write)
 624 {
 625     RBDAIOCB *acb;
 626     RADOSCB *rcb;
 627     rbd_completion_t c;
 628     int64_t off, size;
 629     char *buf;
 630     int r;
 631
 632     BDRVRBDState *s = bs->opaque;
 633
 634     acb = qemu_aio_get(&rbd_aio_pool, bs, cb, opaque);
 635     if (!acb) {
 636         return NULL;
 637     }
 638     acb->write = write;
 639     acb->qiov = qiov;
 640     acb->bounce = qemu_blockalign(bs, qiov->size);
 641     acb->ret = 0;
 642     acb->error = 0;
 643     acb->s = s;
 644     acb->cancelled = 0;
 645     acb->bh = NULL;
 646
 647     if (write) {
 648         qemu_iovec_to_buffer(acb->qiov, acb->bounce);
 649     }
 650
 651     buf = acb->bounce;
 652
 653     off = sector_num * BDRV_SECTOR_SIZE;
 654     size = nb_sectors * BDRV_SECTOR_SIZE;
 655
 656     s->qemu_aio_count++; /* All the RADOSCB */
 657
 658     rcb = g_malloc(sizeof(RADOSCB));
 659     rcb->done = 0;
 660     rcb->acb = acb;
 661     rcb->buf = buf;
 662     rcb->s = acb->s;
 663     rcb->size = size;
 664     r = rbd_aio_create_completion(rcb, (rbd_callback_t) rbd_finish_aiocb, &c);
 665     if (r < 0) {
 666         goto failed;
 667     }
 668
 669     if (write) {
 670         r = rbd_aio_write(s->image, off, size, buf, c);
 671     } else {
 672         r = rbd_aio_read(s->image, off, size, buf, c);
 673     }
 674
 675     if (r < 0) {
 676         goto failed;
 677     }
 678
 679     return &acb->common;
 680
 681 failed:
 682     g_free(rcb);
 683     s->qemu_aio_count--;
 684     qemu_aio_release(acb);
 685     return NULL;
 686 }
 687
 688 static BlockDriverAIOCB *qemu_rbd_aio_readv(BlockDriverState *bs,
 689                                             int64_t sector_num,
 690                                             QEMUIOVector *qiov,
 691                                             int nb_sectors,
 692                                             BlockDriverCompletionFunc *cb,
 693                                             void *opaque)
 694 {
 695     return rbd_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
 696 }
 697
 698 static BlockDriverAIOCB *qemu_rbd_aio_writev(BlockDriverState *bs,
 699                                              int64_t sector_num,
 700                                              QEMUIOVector *qiov,
 701                                              int nb_sectors,
 702                                              BlockDriverCompletionFunc *cb,
 703                                              void *opaque)
 704 {
 705     return rbd_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
 706 }
 707
 708 static int qemu_rbd_co_flush(BlockDriverState *bs)
 709 {
 710 #if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(0, 1, 1)
 711     /* rbd_flush added in 0.1.1 */
 712     BDRVRBDState *s = bs->opaque;
 713     return rbd_flush(s->image);
 714 #else
 715     return 0;
 716 #endif
 717 }
 718
 719 static int qemu_rbd_getinfo(BlockDriverState *bs, BlockDriverInfo *bdi)
 720 {
 721     BDRVRBDState *s = bs->opaque;
 722     rbd_image_info_t info;
 723     int r;
 724
 725     r = rbd_stat(s->image, &info, sizeof(info));
 726     if (r < 0) {
 727         return r;
 728     }
 729
 730     bdi->cluster_size = info.obj_size;
 731     return 0;
 732 }
 733
 734 static int64_t qemu_rbd_getlength(BlockDriverState *bs)
 735 {
 736     BDRVRBDState *s = bs->opaque;
 737     rbd_image_info_t info;
 738     int r;
 739
 740     r = rbd_stat(s->image, &info, sizeof(info));
 741     if (r < 0) {
 742         return r;
 743     }
 744
 745     return info.size;
 746 }
 747
 748 static int qemu_rbd_truncate(BlockDriverState *bs, int64_t offset)
 749 {
 750     BDRVRBDState *s = bs->opaque;
 751     int r;
 752
 753     r = rbd_resize(s->image, offset);
 754     if (r < 0) {
 755         return r;
 756     }
 757
 758     return 0;
 759 }
 760
 761 static int qemu_rbd_snap_create(BlockDriverState *bs,
 762                                 QEMUSnapshotInfo *sn_info)
 763 {
 764     BDRVRBDState *s = bs->opaque;
 765     int r;
 766
 767     if (sn_info->name[0] == '\0') {
 768         return -EINVAL; /* we need a name for rbd snapshots */
 769     }
 770
 771     /*
 772      * rbd snapshots are using the name as the user controlled unique identifier
 773      * we can't use the rbd snapid for that purpose, as it can't be set
 774      */
 775     if (sn_info->id_str[0] != '\0' &&
 776         strcmp(sn_info->id_str, sn_info->name) != 0) {
 777         return -EINVAL;
 778     }
 779
 780     if (strlen(sn_info->name) >= sizeof(sn_info->id_str)) {
 781         return -ERANGE;
 782     }
 783
 784     r = rbd_snap_create(s->image, sn_info->name);
 785     if (r < 0) {
 786         error_report("failed to create snap: %s", strerror(-r));
 787         return r;
 788     }
 789
 790     return 0;
 791 }
 792
 793 static int qemu_rbd_snap_list(BlockDriverState *bs,
 794                               QEMUSnapshotInfo **psn_tab)
 795 {
 796     BDRVRBDState *s = bs->opaque;
 797     QEMUSnapshotInfo *sn_info, *sn_tab = NULL;
 798     int i, snap_count;
 799     rbd_snap_info_t *snaps;
 800     int max_snaps = RBD_MAX_SNAPS;
 801
 802     do {
 803         snaps = g_malloc(sizeof(*snaps) * max_snaps);
 804         snap_count = rbd_snap_list(s->image, snaps, &max_snaps);
 805         if (snap_count < 0) {
 806             g_free(snaps);
 807         }
 808     } while (snap_count == -ERANGE);
 809
 810     if (snap_count <= 0) {
 811         return snap_count;
 812     }
 813
 814     sn_tab = g_malloc0(snap_count * sizeof(QEMUSnapshotInfo));
 815
 816     for (i = 0; i < snap_count; i++) {
 817         const char *snap_name = snaps[i].name;
 818
 819         sn_info = sn_tab + i;
 820         pstrcpy(sn_info->id_str, sizeof(sn_info->id_str), snap_name);
 821         pstrcpy(sn_info->name, sizeof(sn_info->name), snap_name);
 822
 823         sn_info->vm_state_size = snaps[i].size;
 824         sn_info->date_sec = 0;
 825         sn_info->date_nsec = 0;
 826         sn_info->vm_clock_nsec = 0;
 827     }
 828     rbd_snap_list_end(snaps);
 829
 830     *psn_tab = sn_tab;
 831     return snap_count;
 832 }
 833
 834 static QEMUOptionParameter qemu_rbd_create_options[] = {
 835     {
 836      .name = BLOCK_OPT_SIZE,
 837      .type = OPT_SIZE,
 838      .help = "Virtual disk size"
 839     },
 840     {
 841      .name = BLOCK_OPT_CLUSTER_SIZE,
 842      .type = OPT_SIZE,
 843      .help = "RBD object size"
 844     },
 845     {NULL}
 846 };
 847
 848 static BlockDriver bdrv_rbd = {
 849     .format_name        = "rbd",
 850     .instance_size      = sizeof(BDRVRBDState),
 851     .bdrv_file_open     = qemu_rbd_open,
 852     .bdrv_close         = qemu_rbd_close,
 853     .bdrv_create        = qemu_rbd_create,
 854     .bdrv_get_info      = qemu_rbd_getinfo,
 855     .create_options     = qemu_rbd_create_options,
 856     .bdrv_getlength     = qemu_rbd_getlength,
 857     .bdrv_truncate      = qemu_rbd_truncate,
 858     .protocol_name      = "rbd",
 859
 860     .bdrv_aio_readv         = qemu_rbd_aio_readv,
 861     .bdrv_aio_writev        = qemu_rbd_aio_writev,
 862     .bdrv_co_flush_to_disk  = qemu_rbd_co_flush,
 863
 864     .bdrv_snapshot_create   = qemu_rbd_snap_create,
 865     .bdrv_snapshot_list     = qemu_rbd_snap_list,
 866 };
 867
 868 static void bdrv_rbd_init(void)
 869 {
 870     bdrv_register(&bdrv_rbd);
 871 }
 872
 873 block_init(bdrv_rbd_init);