block-migration.c

   1 /*
   2  * QEMU live block migration
   3  *
   4  * Copyright IBM, Corp. 2009
   5  *
   6  * Authors:
   7  *  Liran Schour   <lirans@il.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "block_int.h"
  16 #include "hw/hw.h"
  17 #include "qemu-queue.h"
  18 #include "qemu-timer.h"
  19 #include "monitor.h"
  20 #include "block-migration.h"
  21 #include "migration.h"
  22 #include "blockdev.h"
  23 #include <assert.h>
  24
  25 #define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << BDRV_SECTOR_BITS)
  26
  27 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
  28 #define BLK_MIG_FLAG_EOS                0x02
  29 #define BLK_MIG_FLAG_PROGRESS           0x04
  30
  31 #define MAX_IS_ALLOCATED_SEARCH 65536
  32
  33 //#define DEBUG_BLK_MIGRATION
  34
  35 #ifdef DEBUG_BLK_MIGRATION
  36 #define DPRINTF(fmt, ...) \
  37     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
  38 #else
  39 #define DPRINTF(fmt, ...) \
  40     do { } while (0)
  41 #endif
  42
  43 typedef struct BlkMigDevState {
  44     BlockDriverState *bs;
  45     int bulk_completed;
  46     int shared_base;
  47     int64_t cur_sector;
  48     int64_t cur_dirty;
  49     int64_t completed_sectors;
  50     int64_t total_sectors;
  51     int64_t dirty;
  52     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  53     unsigned long *aio_bitmap;
  54 } BlkMigDevState;
  55
  56 typedef struct BlkMigBlock {
  57     uint8_t *buf;
  58     BlkMigDevState *bmds;
  59     int64_t sector;
  60     int nr_sectors;
  61     struct iovec iov;
  62     QEMUIOVector qiov;
  63     BlockDriverAIOCB *aiocb;
  64     int ret;
  65     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  66 } BlkMigBlock;
  67
  68 typedef struct BlkMigState {
  69     int blk_enable;
  70     int shared_base;
  71     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  72     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
  73     int submitted;
  74     int read_done;
  75     int transferred;
  76     int64_t total_sector_sum;
  77     int prev_progress;
  78     int bulk_completed;
  79     long double total_time;
  80     long double prev_time_offset;
  81     int reads;
  82 } BlkMigState;
  83
  84 static BlkMigState block_mig_state;
  85
  86 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
  87 {
  88     int len;
  89
  90     /* sector number and flags */
  91     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
  92                      | BLK_MIG_FLAG_DEVICE_BLOCK);
  93
  94     /* device name */
  95     len = strlen(blk->bmds->bs->device_name);
  96     qemu_put_byte(f, len);
  97     qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
  98
  99     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 100 }
 101
 102 int blk_mig_active(void)
 103 {
 104     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 105 }
 106
 107 uint64_t blk_mig_bytes_transferred(void)
 108 {
 109     BlkMigDevState *bmds;
 110     uint64_t sum = 0;
 111
 112     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 113         sum += bmds->completed_sectors;
 114     }
 115     return sum << BDRV_SECTOR_BITS;
 116 }
 117
 118 uint64_t blk_mig_bytes_remaining(void)
 119 {
 120     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 121 }
 122
 123 uint64_t blk_mig_bytes_total(void)
 124 {
 125     BlkMigDevState *bmds;
 126     uint64_t sum = 0;
 127
 128     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 129         sum += bmds->total_sectors;
 130     }
 131     return sum << BDRV_SECTOR_BITS;
 132 }
 133
 134 static inline long double compute_read_bwidth(void)
 135 {
 136     assert(block_mig_state.total_time != 0);
 137     return (block_mig_state.reads / block_mig_state.total_time) * BLOCK_SIZE;
 138 }
 139
 140 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
 141 {
 142     int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 143
 144     if ((sector << BDRV_SECTOR_BITS) < bdrv_getlength(bmds->bs)) {
 145         return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
 146             (1UL << (chunk % (sizeof(unsigned long) * 8))));
 147     } else {
 148         return 0;
 149     }
 150 }
 151
 152 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
 153                              int nb_sectors, int set)
 154 {
 155     int64_t start, end;
 156     unsigned long val, idx, bit;
 157
 158     start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
 159     end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
 160
 161     for (; start <= end; start++) {
 162         idx = start / (sizeof(unsigned long) * 8);
 163         bit = start % (sizeof(unsigned long) * 8);
 164         val = bmds->aio_bitmap[idx];
 165         if (set) {
 166             val |= 1UL << bit;
 167         } else {
 168             val &= ~(1UL << bit);
 169         }
 170         bmds->aio_bitmap[idx] = val;
 171     }
 172 }
 173
 174 static void alloc_aio_bitmap(BlkMigDevState *bmds)
 175 {
 176     BlockDriverState *bs = bmds->bs;
 177     int64_t bitmap_size;
 178
 179     bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
 180             BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
 181     bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 182
 183     bmds->aio_bitmap = g_malloc0(bitmap_size);
 184 }
 185
 186 static void blk_mig_read_cb(void *opaque, int ret)
 187 {
 188     long double curr_time = qemu_get_clock_ns(rt_clock);
 189     BlkMigBlock *blk = opaque;
 190
 191     blk->ret = ret;
 192
 193     block_mig_state.reads++;
 194     block_mig_state.total_time += (curr_time - block_mig_state.prev_time_offset);
 195     block_mig_state.prev_time_offset = curr_time;
 196
 197     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
 198     bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
 199
 200     block_mig_state.submitted--;
 201     block_mig_state.read_done++;
 202     assert(block_mig_state.submitted >= 0);
 203 }
 204
 205 static int mig_save_device_bulk(Monitor *mon, QEMUFile *f,
 206                                 BlkMigDevState *bmds)
 207 {
 208     int64_t total_sectors = bmds->total_sectors;
 209     int64_t cur_sector = bmds->cur_sector;
 210     BlockDriverState *bs = bmds->bs;
 211     BlkMigBlock *blk;
 212     int nr_sectors;
 213
 214     if (bmds->shared_base) {
 215         while (cur_sector < total_sectors &&
 216                !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
 217                                   &nr_sectors)) {
 218             cur_sector += nr_sectors;
 219         }
 220     }
 221
 222     if (cur_sector >= total_sectors) {
 223         bmds->cur_sector = bmds->completed_sectors = total_sectors;
 224         return 1;
 225     }
 226
 227     bmds->completed_sectors = cur_sector;
 228
 229     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 230
 231     /* we are going to transfer a full block even if it is not allocated */
 232     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 233
 234     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 235         nr_sectors = total_sectors - cur_sector;
 236     }
 237
 238     blk = g_malloc(sizeof(BlkMigBlock));
 239     blk->buf = g_malloc(BLOCK_SIZE);
 240     blk->bmds = bmds;
 241     blk->sector = cur_sector;
 242     blk->nr_sectors = nr_sectors;
 243
 244     blk->iov.iov_base = blk->buf;
 245     blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 246     qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 247
 248     if (block_mig_state.submitted == 0) {
 249         block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
 250     }
 251
 252     blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
 253                                 nr_sectors, blk_mig_read_cb, blk);
 254     if (!blk->aiocb) {
 255         goto error;
 256     }
 257     block_mig_state.submitted++;
 258
 259     bdrv_reset_dirty(bs, cur_sector, nr_sectors);
 260     bmds->cur_sector = cur_sector + nr_sectors;
 261
 262     return (bmds->cur_sector >= total_sectors);
 263
 264 error:
 265     monitor_printf(mon, "Error reading sector %" PRId64 "\n", cur_sector);
 266     qemu_file_set_error(f);
 267     g_free(blk->buf);
 268     g_free(blk);
 269     return 0;
 270 }
 271
 272 static void set_dirty_tracking(int enable)
 273 {
 274     BlkMigDevState *bmds;
 275
 276     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 277         bdrv_set_dirty_tracking(bmds->bs, enable);
 278     }
 279 }
 280
 281 static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
 282 {
 283     Monitor *mon = opaque;
 284     BlkMigDevState *bmds;
 285     int64_t sectors;
 286
 287     if (!bdrv_is_read_only(bs)) {
 288         sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 289         if (sectors <= 0) {
 290             return;
 291         }
 292
 293         bmds = g_malloc0(sizeof(BlkMigDevState));
 294         bmds->bs = bs;
 295         bmds->bulk_completed = 0;
 296         bmds->total_sectors = sectors;
 297         bmds->completed_sectors = 0;
 298         bmds->shared_base = block_mig_state.shared_base;
 299         alloc_aio_bitmap(bmds);
 300         drive_get_ref(drive_get_by_blockdev(bs));
 301         bdrv_set_in_use(bs, 1);
 302
 303         block_mig_state.total_sector_sum += sectors;
 304
 305         if (bmds->shared_base) {
 306             monitor_printf(mon, "Start migration for %s with shared base "
 307                                 "image\n",
 308                            bs->device_name);
 309         } else {
 310             monitor_printf(mon, "Start full migration for %s\n",
 311                            bs->device_name);
 312         }
 313
 314         QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 315     }
 316 }
 317
 318 static void init_blk_migration(Monitor *mon, QEMUFile *f)
 319 {
 320     block_mig_state.submitted = 0;
 321     block_mig_state.read_done = 0;
 322     block_mig_state.transferred = 0;
 323     block_mig_state.total_sector_sum = 0;
 324     block_mig_state.prev_progress = -1;
 325     block_mig_state.bulk_completed = 0;
 326     block_mig_state.total_time = 0;
 327     block_mig_state.reads = 0;
 328
 329     bdrv_iterate(init_blk_migration_it, mon);
 330 }
 331
 332 static int blk_mig_save_bulked_block(Monitor *mon, QEMUFile *f)
 333 {
 334     int64_t completed_sector_sum = 0;
 335     BlkMigDevState *bmds;
 336     int progress;
 337     int ret = 0;
 338
 339     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 340         if (bmds->bulk_completed == 0) {
 341             if (mig_save_device_bulk(mon, f, bmds) == 1) {
 342                 /* completed bulk section for this device */
 343                 bmds->bulk_completed = 1;
 344             }
 345             completed_sector_sum += bmds->completed_sectors;
 346             ret = 1;
 347             break;
 348         } else {
 349             completed_sector_sum += bmds->completed_sectors;
 350         }
 351     }
 352
 353     if (block_mig_state.total_sector_sum != 0) {
 354         progress = completed_sector_sum * 100 /
 355                    block_mig_state.total_sector_sum;
 356     } else {
 357         progress = 100;
 358     }
 359     if (progress != block_mig_state.prev_progress) {
 360         block_mig_state.prev_progress = progress;
 361         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 362                          | BLK_MIG_FLAG_PROGRESS);
 363         monitor_printf(mon, "Completed %d %%\r", progress);
 364         monitor_flush(mon);
 365     }
 366
 367     return ret;
 368 }
 369
 370 static void blk_mig_reset_dirty_cursor(void)
 371 {
 372     BlkMigDevState *bmds;
 373
 374     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 375         bmds->cur_dirty = 0;
 376     }
 377 }
 378
 379 static int mig_save_device_dirty(Monitor *mon, QEMUFile *f,
 380                                  BlkMigDevState *bmds, int is_async)
 381 {
 382     BlkMigBlock *blk;
 383     int64_t total_sectors = bmds->total_sectors;
 384     int64_t sector;
 385     int nr_sectors;
 386
 387     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 388         if (bmds_aio_inflight(bmds, sector)) {
 389             qemu_aio_flush();
 390         }
 391         if (bdrv_get_dirty(bmds->bs, sector)) {
 392
 393             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 394                 nr_sectors = total_sectors - sector;
 395             } else {
 396                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 397             }
 398             blk = g_malloc(sizeof(BlkMigBlock));
 399             blk->buf = g_malloc(BLOCK_SIZE);
 400             blk->bmds = bmds;
 401             blk->sector = sector;
 402             blk->nr_sectors = nr_sectors;
 403
 404             if (is_async) {
 405                 blk->iov.iov_base = blk->buf;
 406                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 407                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 408
 409                 if (block_mig_state.submitted == 0) {
 410                     block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
 411                 }
 412
 413                 blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
 414                                             nr_sectors, blk_mig_read_cb, blk);
 415                 if (!blk->aiocb) {
 416                     goto error;
 417                 }
 418                 block_mig_state.submitted++;
 419                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 420             } else {
 421                 if (bdrv_read(bmds->bs, sector, blk->buf,
 422                               nr_sectors) < 0) {
 423                     goto error;
 424                 }
 425                 blk_send(f, blk);
 426
 427                 g_free(blk->buf);
 428                 g_free(blk);
 429             }
 430
 431             bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
 432             break;
 433         }
 434         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 435         bmds->cur_dirty = sector;
 436     }
 437
 438     return (bmds->cur_dirty >= bmds->total_sectors);
 439
 440 error:
 441     monitor_printf(mon, "Error reading sector %" PRId64 "\n", sector);
 442     qemu_file_set_error(f);
 443     g_free(blk->buf);
 444     g_free(blk);
 445     return 0;
 446 }
 447
 448 static int blk_mig_save_dirty_block(Monitor *mon, QEMUFile *f, int is_async)
 449 {
 450     BlkMigDevState *bmds;
 451     int ret = 0;
 452
 453     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 454         if (mig_save_device_dirty(mon, f, bmds, is_async) == 0) {
 455             ret = 1;
 456             break;
 457         }
 458     }
 459
 460     return ret;
 461 }
 462
 463 static void flush_blks(QEMUFile* f)
 464 {
 465     BlkMigBlock *blk;
 466
 467     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 468             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 469             block_mig_state.transferred);
 470
 471     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 472         if (qemu_file_rate_limit(f)) {
 473             break;
 474         }
 475         if (blk->ret < 0) {
 476             qemu_file_set_error(f);
 477             break;
 478         }
 479         blk_send(f, blk);
 480
 481         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 482         g_free(blk->buf);
 483         g_free(blk);
 484
 485         block_mig_state.read_done--;
 486         block_mig_state.transferred++;
 487         assert(block_mig_state.read_done >= 0);
 488     }
 489
 490     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 491             block_mig_state.submitted, block_mig_state.read_done,
 492             block_mig_state.transferred);
 493 }
 494
 495 static int64_t get_remaining_dirty(void)
 496 {
 497     BlkMigDevState *bmds;
 498     int64_t dirty = 0;
 499
 500     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 501         dirty += bdrv_get_dirty_count(bmds->bs);
 502     }
 503
 504     return dirty * BLOCK_SIZE;
 505 }
 506
 507 static int is_stage2_completed(void)
 508 {
 509     int64_t remaining_dirty;
 510     long double bwidth;
 511
 512     if (block_mig_state.bulk_completed == 1) {
 513
 514         remaining_dirty = get_remaining_dirty();
 515         if (remaining_dirty == 0) {
 516             return 1;
 517         }
 518
 519         bwidth = compute_read_bwidth();
 520
 521         if ((remaining_dirty / bwidth) <=
 522             migrate_max_downtime()) {
 523             /* finish stage2 because we think that we can finish remaing work
 524                below max_downtime */
 525
 526             return 1;
 527         }
 528     }
 529
 530     return 0;
 531 }
 532
 533 static void blk_mig_cleanup(Monitor *mon)
 534 {
 535     BlkMigDevState *bmds;
 536     BlkMigBlock *blk;
 537
 538     set_dirty_tracking(0);
 539
 540     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 541         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 542         bdrv_set_in_use(bmds->bs, 0);
 543         drive_put_ref(drive_get_by_blockdev(bmds->bs));
 544         g_free(bmds->aio_bitmap);
 545         g_free(bmds);
 546     }
 547
 548     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 549         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 550         g_free(blk->buf);
 551         g_free(blk);
 552     }
 553
 554     monitor_printf(mon, "\n");
 555 }
 556
 557 static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
 558 {
 559     DPRINTF("Enter save live stage %d submitted %d transferred %d\n",
 560             stage, block_mig_state.submitted, block_mig_state.transferred);
 561
 562     if (stage < 0) {
 563         blk_mig_cleanup(mon);
 564         return 0;
 565     }
 566
 567     if (block_mig_state.blk_enable != 1) {
 568         /* no need to migrate storage */
 569         qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 570         return 1;
 571     }
 572
 573     if (stage == 1) {
 574         init_blk_migration(mon, f);
 575
 576         /* start track dirty blocks */
 577         set_dirty_tracking(1);
 578     }
 579
 580     flush_blks(f);
 581
 582     if (qemu_file_has_error(f)) {
 583         blk_mig_cleanup(mon);
 584         return 0;
 585     }
 586
 587     blk_mig_reset_dirty_cursor();
 588
 589     if (stage == 2) {
 590         /* control the rate of transfer */
 591         while ((block_mig_state.submitted +
 592                 block_mig_state.read_done) * BLOCK_SIZE <
 593                qemu_file_get_rate_limit(f)) {
 594             if (block_mig_state.bulk_completed == 0) {
 595                 /* first finish the bulk phase */
 596                 if (blk_mig_save_bulked_block(mon, f) == 0) {
 597                     /* finished saving bulk on all devices */
 598                     block_mig_state.bulk_completed = 1;
 599                 }
 600             } else {
 601                 if (blk_mig_save_dirty_block(mon, f, 1) == 0) {
 602                     /* no more dirty blocks */
 603                     break;
 604                 }
 605             }
 606         }
 607
 608         flush_blks(f);
 609
 610         if (qemu_file_has_error(f)) {
 611             blk_mig_cleanup(mon);
 612             return 0;
 613         }
 614     }
 615
 616     if (stage == 3) {
 617         /* we know for sure that save bulk is completed and
 618            all async read completed */
 619         assert(block_mig_state.submitted == 0);
 620
 621         while (blk_mig_save_dirty_block(mon, f, 0) != 0);
 622         blk_mig_cleanup(mon);
 623
 624         /* report completion */
 625         qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 626
 627         if (qemu_file_has_error(f)) {
 628             return 0;
 629         }
 630
 631         monitor_printf(mon, "Block migration completed\n");
 632     }
 633
 634     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 635
 636     return ((stage == 2) && is_stage2_completed());
 637 }
 638
 639 static int block_load(QEMUFile *f, void *opaque, int version_id)
 640 {
 641     static int banner_printed;
 642     int len, flags;
 643     char device_name[256];
 644     int64_t addr;
 645     BlockDriverState *bs, *bs_prev = NULL;
 646     uint8_t *buf;
 647     int64_t total_sectors = 0;
 648     int nr_sectors;
 649
 650     do {
 651         addr = qemu_get_be64(f);
 652
 653         flags = addr & ~BDRV_SECTOR_MASK;
 654         addr >>= BDRV_SECTOR_BITS;
 655
 656         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 657             int ret;
 658             /* get device name */
 659             len = qemu_get_byte(f);
 660             qemu_get_buffer(f, (uint8_t *)device_name, len);
 661             device_name[len] = '\0';
 662
 663             bs = bdrv_find(device_name);
 664             if (!bs) {
 665                 fprintf(stderr, "Error unknown block device %s\n",
 666                         device_name);
 667                 return -EINVAL;
 668             }
 669
 670             if (bs != bs_prev) {
 671                 bs_prev = bs;
 672                 total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 673                 if (total_sectors <= 0) {
 674                     error_report("Error getting length of block device %s",
 675                                  device_name);
 676                     return -EINVAL;
 677                 }
 678             }
 679
 680             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 681                 nr_sectors = total_sectors - addr;
 682             } else {
 683                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 684             }
 685
 686             buf = g_malloc(BLOCK_SIZE);
 687
 688             qemu_get_buffer(f, buf, BLOCK_SIZE);
 689             ret = bdrv_write(bs, addr, buf, nr_sectors);
 690
 691             g_free(buf);
 692             if (ret < 0) {
 693                 return ret;
 694             }
 695         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 696             if (!banner_printed) {
 697                 printf("Receiving block device images\n");
 698                 banner_printed = 1;
 699             }
 700             printf("Completed %d %%%c", (int)addr,
 701                    (addr == 100) ? '\n' : '\r');
 702             fflush(stdout);
 703         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 704             fprintf(stderr, "Unknown flags\n");
 705             return -EINVAL;
 706         }
 707         if (qemu_file_has_error(f)) {
 708             return -EIO;
 709         }
 710     } while (!(flags & BLK_MIG_FLAG_EOS));
 711
 712     return 0;
 713 }
 714
 715 static void block_set_params(int blk_enable, int shared_base, void *opaque)
 716 {
 717     block_mig_state.blk_enable = blk_enable;
 718     block_mig_state.shared_base = shared_base;
 719
 720     /* shared base means that blk_enable = 1 */
 721     block_mig_state.blk_enable |= shared_base;
 722 }
 723
 724 void blk_mig_init(void)
 725 {
 726     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 727     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 728
 729     register_savevm_live(NULL, "block", 0, 1, block_set_params,
 730                          block_save_live, NULL, block_load, &block_mig_state);
 731 }