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  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "block_int.h"
  18 #include "hw/hw.h"
  19 #include "qemu-queue.h"
  20 #include "qemu-timer.h"
  21 #include "monitor.h"
  22 #include "block-migration.h"
  23 #include "migration.h"
  24 #include "blockdev.h"
  25 #include <assert.h>
  26
  27 #define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << BDRV_SECTOR_BITS)
  28
  29 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
  30 #define BLK_MIG_FLAG_EOS                0x02
  31 #define BLK_MIG_FLAG_PROGRESS           0x04
  32
  33 #define MAX_IS_ALLOCATED_SEARCH 65536
  34
  35 //#define DEBUG_BLK_MIGRATION
  36
  37 #ifdef DEBUG_BLK_MIGRATION
  38 #define DPRINTF(fmt, ...) \
  39     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
  40 #else
  41 #define DPRINTF(fmt, ...) \
  42     do { } while (0)
  43 #endif
  44
  45 typedef struct BlkMigDevState {
  46     BlockDriverState *bs;
  47     int bulk_completed;
  48     int shared_base;
  49     int64_t cur_sector;
  50     int64_t cur_dirty;
  51     int64_t completed_sectors;
  52     int64_t total_sectors;
  53     int64_t dirty;
  54     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  55     unsigned long *aio_bitmap;
  56 } BlkMigDevState;
  57
  58 typedef struct BlkMigBlock {
  59     uint8_t *buf;
  60     BlkMigDevState *bmds;
  61     int64_t sector;
  62     int nr_sectors;
  63     struct iovec iov;
  64     QEMUIOVector qiov;
  65     BlockDriverAIOCB *aiocb;
  66     int ret;
  67     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  68 } BlkMigBlock;
  69
  70 typedef struct BlkMigState {
  71     int blk_enable;
  72     int shared_base;
  73     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  74     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
  75     int submitted;
  76     int read_done;
  77     int transferred;
  78     int64_t total_sector_sum;
  79     int prev_progress;
  80     int bulk_completed;
  81     long double total_time;
  82     long double prev_time_offset;
  83     int reads;
  84 } BlkMigState;
  85
  86 static BlkMigState block_mig_state;
  87
  88 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
  89 {
  90     int len;
  91
  92     /* sector number and flags */
  93     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
  94                      | BLK_MIG_FLAG_DEVICE_BLOCK);
  95
  96     /* device name */
  97     len = strlen(blk->bmds->bs->device_name);
  98     qemu_put_byte(f, len);
  99     qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
 100
 101     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 102 }
 103
 104 int blk_mig_active(void)
 105 {
 106     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 107 }
 108
 109 uint64_t blk_mig_bytes_transferred(void)
 110 {
 111     BlkMigDevState *bmds;
 112     uint64_t sum = 0;
 113
 114     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 115         sum += bmds->completed_sectors;
 116     }
 117     return sum << BDRV_SECTOR_BITS;
 118 }
 119
 120 uint64_t blk_mig_bytes_remaining(void)
 121 {
 122     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 123 }
 124
 125 uint64_t blk_mig_bytes_total(void)
 126 {
 127     BlkMigDevState *bmds;
 128     uint64_t sum = 0;
 129
 130     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 131         sum += bmds->total_sectors;
 132     }
 133     return sum << BDRV_SECTOR_BITS;
 134 }
 135
 136 static inline long double compute_read_bwidth(void)
 137 {
 138     assert(block_mig_state.total_time != 0);
 139     return (block_mig_state.reads / block_mig_state.total_time) * BLOCK_SIZE;
 140 }
 141
 142 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
 143 {
 144     int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 145
 146     if ((sector << BDRV_SECTOR_BITS) < bdrv_getlength(bmds->bs)) {
 147         return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
 148             (1UL << (chunk % (sizeof(unsigned long) * 8))));
 149     } else {
 150         return 0;
 151     }
 152 }
 153
 154 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
 155                              int nb_sectors, int set)
 156 {
 157     int64_t start, end;
 158     unsigned long val, idx, bit;
 159
 160     start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
 161     end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
 162
 163     for (; start <= end; start++) {
 164         idx = start / (sizeof(unsigned long) * 8);
 165         bit = start % (sizeof(unsigned long) * 8);
 166         val = bmds->aio_bitmap[idx];
 167         if (set) {
 168             val |= 1UL << bit;
 169         } else {
 170             val &= ~(1UL << bit);
 171         }
 172         bmds->aio_bitmap[idx] = val;
 173     }
 174 }
 175
 176 static void alloc_aio_bitmap(BlkMigDevState *bmds)
 177 {
 178     BlockDriverState *bs = bmds->bs;
 179     int64_t bitmap_size;
 180
 181     bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
 182             BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
 183     bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 184
 185     bmds->aio_bitmap = g_malloc0(bitmap_size);
 186 }
 187
 188 static void blk_mig_read_cb(void *opaque, int ret)
 189 {
 190     long double curr_time = qemu_get_clock_ns(rt_clock);
 191     BlkMigBlock *blk = opaque;
 192
 193     blk->ret = ret;
 194
 195     block_mig_state.reads++;
 196     block_mig_state.total_time += (curr_time - block_mig_state.prev_time_offset);
 197     block_mig_state.prev_time_offset = curr_time;
 198
 199     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
 200     bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
 201
 202     block_mig_state.submitted--;
 203     block_mig_state.read_done++;
 204     assert(block_mig_state.submitted >= 0);
 205 }
 206
 207 static int mig_save_device_bulk(Monitor *mon, QEMUFile *f,
 208                                 BlkMigDevState *bmds)
 209 {
 210     int64_t total_sectors = bmds->total_sectors;
 211     int64_t cur_sector = bmds->cur_sector;
 212     BlockDriverState *bs = bmds->bs;
 213     BlkMigBlock *blk;
 214     int nr_sectors;
 215
 216     if (bmds->shared_base) {
 217         while (cur_sector < total_sectors &&
 218                !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
 219                                   &nr_sectors)) {
 220             cur_sector += nr_sectors;
 221         }
 222     }
 223
 224     if (cur_sector >= total_sectors) {
 225         bmds->cur_sector = bmds->completed_sectors = total_sectors;
 226         return 1;
 227     }
 228
 229     bmds->completed_sectors = cur_sector;
 230
 231     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 232
 233     /* we are going to transfer a full block even if it is not allocated */
 234     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 235
 236     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 237         nr_sectors = total_sectors - cur_sector;
 238     }
 239
 240     blk = g_malloc(sizeof(BlkMigBlock));
 241     blk->buf = g_malloc(BLOCK_SIZE);
 242     blk->bmds = bmds;
 243     blk->sector = cur_sector;
 244     blk->nr_sectors = nr_sectors;
 245
 246     blk->iov.iov_base = blk->buf;
 247     blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 248     qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 249
 250     if (block_mig_state.submitted == 0) {
 251         block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
 252     }
 253
 254     blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
 255                                 nr_sectors, blk_mig_read_cb, blk);
 256     block_mig_state.submitted++;
 257
 258     bdrv_reset_dirty(bs, cur_sector, nr_sectors);
 259     bmds->cur_sector = cur_sector + nr_sectors;
 260
 261     return (bmds->cur_sector >= total_sectors);
 262 }
 263
 264 static void set_dirty_tracking(int enable)
 265 {
 266     BlkMigDevState *bmds;
 267
 268     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 269         bdrv_set_dirty_tracking(bmds->bs, enable);
 270     }
 271 }
 272
 273 static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
 274 {
 275     Monitor *mon = opaque;
 276     BlkMigDevState *bmds;
 277     int64_t sectors;
 278
 279     if (!bdrv_is_read_only(bs)) {
 280         sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 281         if (sectors <= 0) {
 282             return;
 283         }
 284
 285         bmds = g_malloc0(sizeof(BlkMigDevState));
 286         bmds->bs = bs;
 287         bmds->bulk_completed = 0;
 288         bmds->total_sectors = sectors;
 289         bmds->completed_sectors = 0;
 290         bmds->shared_base = block_mig_state.shared_base;
 291         alloc_aio_bitmap(bmds);
 292         drive_get_ref(drive_get_by_blockdev(bs));
 293         bdrv_set_in_use(bs, 1);
 294
 295         block_mig_state.total_sector_sum += sectors;
 296
 297         if (bmds->shared_base) {
 298             monitor_printf(mon, "Start migration for %s with shared base "
 299                                 "image\n",
 300                            bs->device_name);
 301         } else {
 302             monitor_printf(mon, "Start full migration for %s\n",
 303                            bs->device_name);
 304         }
 305
 306         QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 307     }
 308 }
 309
 310 static void init_blk_migration(Monitor *mon, QEMUFile *f)
 311 {
 312     block_mig_state.submitted = 0;
 313     block_mig_state.read_done = 0;
 314     block_mig_state.transferred = 0;
 315     block_mig_state.total_sector_sum = 0;
 316     block_mig_state.prev_progress = -1;
 317     block_mig_state.bulk_completed = 0;
 318     block_mig_state.total_time = 0;
 319     block_mig_state.reads = 0;
 320
 321     bdrv_iterate(init_blk_migration_it, mon);
 322 }
 323
 324 static int blk_mig_save_bulked_block(Monitor *mon, QEMUFile *f)
 325 {
 326     int64_t completed_sector_sum = 0;
 327     BlkMigDevState *bmds;
 328     int progress;
 329     int ret = 0;
 330
 331     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 332         if (bmds->bulk_completed == 0) {
 333             if (mig_save_device_bulk(mon, f, bmds) == 1) {
 334                 /* completed bulk section for this device */
 335                 bmds->bulk_completed = 1;
 336             }
 337             completed_sector_sum += bmds->completed_sectors;
 338             ret = 1;
 339             break;
 340         } else {
 341             completed_sector_sum += bmds->completed_sectors;
 342         }
 343     }
 344
 345     if (block_mig_state.total_sector_sum != 0) {
 346         progress = completed_sector_sum * 100 /
 347                    block_mig_state.total_sector_sum;
 348     } else {
 349         progress = 100;
 350     }
 351     if (progress != block_mig_state.prev_progress) {
 352         block_mig_state.prev_progress = progress;
 353         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 354                          | BLK_MIG_FLAG_PROGRESS);
 355         monitor_printf(mon, "Completed %d %%\r", progress);
 356         monitor_flush(mon);
 357     }
 358
 359     return ret;
 360 }
 361
 362 static void blk_mig_reset_dirty_cursor(void)
 363 {
 364     BlkMigDevState *bmds;
 365
 366     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 367         bmds->cur_dirty = 0;
 368     }
 369 }
 370
 371 static int mig_save_device_dirty(Monitor *mon, QEMUFile *f,
 372                                  BlkMigDevState *bmds, int is_async)
 373 {
 374     BlkMigBlock *blk;
 375     int64_t total_sectors = bmds->total_sectors;
 376     int64_t sector;
 377     int nr_sectors;
 378     int ret = -EIO;
 379
 380     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 381         if (bmds_aio_inflight(bmds, sector)) {
 382             bdrv_drain_all();
 383         }
 384         if (bdrv_get_dirty(bmds->bs, sector)) {
 385
 386             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 387                 nr_sectors = total_sectors - sector;
 388             } else {
 389                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 390             }
 391             blk = g_malloc(sizeof(BlkMigBlock));
 392             blk->buf = g_malloc(BLOCK_SIZE);
 393             blk->bmds = bmds;
 394             blk->sector = sector;
 395             blk->nr_sectors = nr_sectors;
 396
 397             if (is_async) {
 398                 blk->iov.iov_base = blk->buf;
 399                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 400                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 401
 402                 if (block_mig_state.submitted == 0) {
 403                     block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
 404                 }
 405
 406                 blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
 407                                             nr_sectors, blk_mig_read_cb, blk);
 408                 block_mig_state.submitted++;
 409                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 410             } else {
 411                 ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
 412                 if (ret < 0) {
 413                     goto error;
 414                 }
 415                 blk_send(f, blk);
 416
 417                 g_free(blk->buf);
 418                 g_free(blk);
 419             }
 420
 421             bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
 422             break;
 423         }
 424         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 425         bmds->cur_dirty = sector;
 426     }
 427
 428     return (bmds->cur_dirty >= bmds->total_sectors);
 429
 430 error:
 431     monitor_printf(mon, "Error reading sector %" PRId64 "\n", sector);
 432     qemu_file_set_error(f, ret);
 433     g_free(blk->buf);
 434     g_free(blk);
 435     return 0;
 436 }
 437
 438 static int blk_mig_save_dirty_block(Monitor *mon, QEMUFile *f, int is_async)
 439 {
 440     BlkMigDevState *bmds;
 441     int ret = 0;
 442
 443     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 444         if (mig_save_device_dirty(mon, f, bmds, is_async) == 0) {
 445             ret = 1;
 446             break;
 447         }
 448     }
 449
 450     return ret;
 451 }
 452
 453 static void flush_blks(QEMUFile* f)
 454 {
 455     BlkMigBlock *blk;
 456
 457     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 458             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 459             block_mig_state.transferred);
 460
 461     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 462         if (qemu_file_rate_limit(f)) {
 463             break;
 464         }
 465         if (blk->ret < 0) {
 466             qemu_file_set_error(f, blk->ret);
 467             break;
 468         }
 469         blk_send(f, blk);
 470
 471         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 472         g_free(blk->buf);
 473         g_free(blk);
 474
 475         block_mig_state.read_done--;
 476         block_mig_state.transferred++;
 477         assert(block_mig_state.read_done >= 0);
 478     }
 479
 480     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 481             block_mig_state.submitted, block_mig_state.read_done,
 482             block_mig_state.transferred);
 483 }
 484
 485 static int64_t get_remaining_dirty(void)
 486 {
 487     BlkMigDevState *bmds;
 488     int64_t dirty = 0;
 489
 490     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 491         dirty += bdrv_get_dirty_count(bmds->bs);
 492     }
 493
 494     return dirty * BLOCK_SIZE;
 495 }
 496
 497 static int is_stage2_completed(void)
 498 {
 499     int64_t remaining_dirty;
 500     long double bwidth;
 501
 502     if (block_mig_state.bulk_completed == 1) {
 503
 504         remaining_dirty = get_remaining_dirty();
 505         if (remaining_dirty == 0) {
 506             return 1;
 507         }
 508
 509         bwidth = compute_read_bwidth();
 510
 511         if ((remaining_dirty / bwidth) <=
 512             migrate_max_downtime()) {
 513             /* finish stage2 because we think that we can finish remaining work
 514                below max_downtime */
 515
 516             return 1;
 517         }
 518     }
 519
 520     return 0;
 521 }
 522
 523 static void blk_mig_cleanup(Monitor *mon)
 524 {
 525     BlkMigDevState *bmds;
 526     BlkMigBlock *blk;
 527
 528     set_dirty_tracking(0);
 529
 530     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 531         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 532         bdrv_set_in_use(bmds->bs, 0);
 533         drive_put_ref(drive_get_by_blockdev(bmds->bs));
 534         g_free(bmds->aio_bitmap);
 535         g_free(bmds);
 536     }
 537
 538     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 539         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 540         g_free(blk->buf);
 541         g_free(blk);
 542     }
 543
 544     monitor_printf(mon, "\n");
 545 }
 546
 547 static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
 548 {
 549     int ret;
 550
 551     DPRINTF("Enter save live stage %d submitted %d transferred %d\n",
 552             stage, block_mig_state.submitted, block_mig_state.transferred);
 553
 554     if (stage < 0) {
 555         blk_mig_cleanup(mon);
 556         return 0;
 557     }
 558
 559     if (block_mig_state.blk_enable != 1) {
 560         /* no need to migrate storage */
 561         qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 562         return 1;
 563     }
 564
 565     if (stage == 1) {
 566         init_blk_migration(mon, f);
 567
 568         /* start track dirty blocks */
 569         set_dirty_tracking(1);
 570     }
 571
 572     flush_blks(f);
 573
 574     ret = qemu_file_get_error(f);
 575     if (ret) {
 576         blk_mig_cleanup(mon);
 577         return ret;
 578     }
 579
 580     blk_mig_reset_dirty_cursor();
 581
 582     if (stage == 2) {
 583         /* control the rate of transfer */
 584         while ((block_mig_state.submitted +
 585                 block_mig_state.read_done) * BLOCK_SIZE <
 586                qemu_file_get_rate_limit(f)) {
 587             if (block_mig_state.bulk_completed == 0) {
 588                 /* first finish the bulk phase */
 589                 if (blk_mig_save_bulked_block(mon, f) == 0) {
 590                     /* finished saving bulk on all devices */
 591                     block_mig_state.bulk_completed = 1;
 592                 }
 593             } else {
 594                 if (blk_mig_save_dirty_block(mon, f, 1) == 0) {
 595                     /* no more dirty blocks */
 596                     break;
 597                 }
 598             }
 599         }
 600
 601         flush_blks(f);
 602
 603         ret = qemu_file_get_error(f);
 604         if (ret) {
 605             blk_mig_cleanup(mon);
 606             return ret;
 607         }
 608     }
 609
 610     if (stage == 3) {
 611         /* we know for sure that save bulk is completed and
 612            all async read completed */
 613         assert(block_mig_state.submitted == 0);
 614
 615         while (blk_mig_save_dirty_block(mon, f, 0) != 0);
 616         blk_mig_cleanup(mon);
 617
 618         /* report completion */
 619         qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 620
 621         ret = qemu_file_get_error(f);
 622         if (ret) {
 623             return ret;
 624         }
 625
 626         monitor_printf(mon, "Block migration completed\n");
 627     }
 628
 629     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 630
 631     return ((stage == 2) && is_stage2_completed());
 632 }
 633
 634 static int block_load(QEMUFile *f, void *opaque, int version_id)
 635 {
 636     static int banner_printed;
 637     int len, flags;
 638     char device_name[256];
 639     int64_t addr;
 640     BlockDriverState *bs, *bs_prev = NULL;
 641     uint8_t *buf;
 642     int64_t total_sectors = 0;
 643     int nr_sectors;
 644     int ret;
 645
 646     do {
 647         addr = qemu_get_be64(f);
 648
 649         flags = addr & ~BDRV_SECTOR_MASK;
 650         addr >>= BDRV_SECTOR_BITS;
 651
 652         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 653             /* get device name */
 654             len = qemu_get_byte(f);
 655             qemu_get_buffer(f, (uint8_t *)device_name, len);
 656             device_name[len] = '\0';
 657
 658             bs = bdrv_find(device_name);
 659             if (!bs) {
 660                 fprintf(stderr, "Error unknown block device %s\n",
 661                         device_name);
 662                 return -EINVAL;
 663             }
 664
 665             if (bs != bs_prev) {
 666                 bs_prev = bs;
 667                 total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 668                 if (total_sectors <= 0) {
 669                     error_report("Error getting length of block device %s",
 670                                  device_name);
 671                     return -EINVAL;
 672                 }
 673             }
 674
 675             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 676                 nr_sectors = total_sectors - addr;
 677             } else {
 678                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 679             }
 680
 681             buf = g_malloc(BLOCK_SIZE);
 682
 683             qemu_get_buffer(f, buf, BLOCK_SIZE);
 684             ret = bdrv_write(bs, addr, buf, nr_sectors);
 685
 686             g_free(buf);
 687             if (ret < 0) {
 688                 return ret;
 689             }
 690         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 691             if (!banner_printed) {
 692                 printf("Receiving block device images\n");
 693                 banner_printed = 1;
 694             }
 695             printf("Completed %d %%%c", (int)addr,
 696                    (addr == 100) ? '\n' : '\r');
 697             fflush(stdout);
 698         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 699             fprintf(stderr, "Unknown flags\n");
 700             return -EINVAL;
 701         }
 702         ret = qemu_file_get_error(f);
 703         if (ret != 0) {
 704             return ret;
 705         }
 706     } while (!(flags & BLK_MIG_FLAG_EOS));
 707
 708     return 0;
 709 }
 710
 711 static void block_set_params(int blk_enable, int shared_base, void *opaque)
 712 {
 713     block_mig_state.blk_enable = blk_enable;
 714     block_mig_state.shared_base = shared_base;
 715
 716     /* shared base means that blk_enable = 1 */
 717     block_mig_state.blk_enable |= shared_base;
 718 }
 719
 720 void blk_mig_init(void)
 721 {
 722     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 723     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 724
 725     register_savevm_live(NULL, "block", 0, 1, block_set_params,
 726                          block_save_live, NULL, block_load, &block_mig_state);
 727 }