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, -EIO);
 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     int ret = -EIO;
 387
 388     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 389         if (bmds_aio_inflight(bmds, sector)) {
 390             qemu_aio_flush();
 391         }
 392         if (bdrv_get_dirty(bmds->bs, sector)) {
 393
 394             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 395                 nr_sectors = total_sectors - sector;
 396             } else {
 397                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 398             }
 399             blk = g_malloc(sizeof(BlkMigBlock));
 400             blk->buf = g_malloc(BLOCK_SIZE);
 401             blk->bmds = bmds;
 402             blk->sector = sector;
 403             blk->nr_sectors = nr_sectors;
 404
 405             if (is_async) {
 406                 blk->iov.iov_base = blk->buf;
 407                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 408                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 409
 410                 if (block_mig_state.submitted == 0) {
 411                     block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
 412                 }
 413
 414                 blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
 415                                             nr_sectors, blk_mig_read_cb, blk);
 416                 if (!blk->aiocb) {
 417                     goto error;
 418                 }
 419                 block_mig_state.submitted++;
 420                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 421             } else {
 422                 ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
 423                 if (ret < 0) {
 424                     goto error;
 425                 }
 426                 blk_send(f, blk);
 427
 428                 g_free(blk->buf);
 429                 g_free(blk);
 430             }
 431
 432             bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
 433             break;
 434         }
 435         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 436         bmds->cur_dirty = sector;
 437     }
 438
 439     return (bmds->cur_dirty >= bmds->total_sectors);
 440
 441 error:
 442     monitor_printf(mon, "Error reading sector %" PRId64 "\n", sector);
 443     qemu_file_set_error(f, ret);
 444     g_free(blk->buf);
 445     g_free(blk);
 446     return 0;
 447 }
 448
 449 static int blk_mig_save_dirty_block(Monitor *mon, QEMUFile *f, int is_async)
 450 {
 451     BlkMigDevState *bmds;
 452     int ret = 0;
 453
 454     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 455         if (mig_save_device_dirty(mon, f, bmds, is_async) == 0) {
 456             ret = 1;
 457             break;
 458         }
 459     }
 460
 461     return ret;
 462 }
 463
 464 static void flush_blks(QEMUFile* f)
 465 {
 466     BlkMigBlock *blk;
 467
 468     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 469             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 470             block_mig_state.transferred);
 471
 472     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 473         if (qemu_file_rate_limit(f)) {
 474             break;
 475         }
 476         if (blk->ret < 0) {
 477             qemu_file_set_error(f, blk->ret);
 478             break;
 479         }
 480         blk_send(f, blk);
 481
 482         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 483         g_free(blk->buf);
 484         g_free(blk);
 485
 486         block_mig_state.read_done--;
 487         block_mig_state.transferred++;
 488         assert(block_mig_state.read_done >= 0);
 489     }
 490
 491     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 492             block_mig_state.submitted, block_mig_state.read_done,
 493             block_mig_state.transferred);
 494 }
 495
 496 static int64_t get_remaining_dirty(void)
 497 {
 498     BlkMigDevState *bmds;
 499     int64_t dirty = 0;
 500
 501     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 502         dirty += bdrv_get_dirty_count(bmds->bs);
 503     }
 504
 505     return dirty * BLOCK_SIZE;
 506 }
 507
 508 static int is_stage2_completed(void)
 509 {
 510     int64_t remaining_dirty;
 511     long double bwidth;
 512
 513     if (block_mig_state.bulk_completed == 1) {
 514
 515         remaining_dirty = get_remaining_dirty();
 516         if (remaining_dirty == 0) {
 517             return 1;
 518         }
 519
 520         bwidth = compute_read_bwidth();
 521
 522         if ((remaining_dirty / bwidth) <=
 523             migrate_max_downtime()) {
 524             /* finish stage2 because we think that we can finish remaining work
 525                below max_downtime */
 526
 527             return 1;
 528         }
 529     }
 530
 531     return 0;
 532 }
 533
 534 static void blk_mig_cleanup(Monitor *mon)
 535 {
 536     BlkMigDevState *bmds;
 537     BlkMigBlock *blk;
 538
 539     set_dirty_tracking(0);
 540
 541     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 542         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 543         bdrv_set_in_use(bmds->bs, 0);
 544         drive_put_ref(drive_get_by_blockdev(bmds->bs));
 545         g_free(bmds->aio_bitmap);
 546         g_free(bmds);
 547     }
 548
 549     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 550         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 551         g_free(blk->buf);
 552         g_free(blk);
 553     }
 554
 555     monitor_printf(mon, "\n");
 556 }
 557
 558 static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
 559 {
 560     int ret;
 561
 562     DPRINTF("Enter save live stage %d submitted %d transferred %d\n",
 563             stage, block_mig_state.submitted, block_mig_state.transferred);
 564
 565     if (stage < 0) {
 566         blk_mig_cleanup(mon);
 567         return 0;
 568     }
 569
 570     if (block_mig_state.blk_enable != 1) {
 571         /* no need to migrate storage */
 572         qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 573         return 1;
 574     }
 575
 576     if (stage == 1) {
 577         init_blk_migration(mon, f);
 578
 579         /* start track dirty blocks */
 580         set_dirty_tracking(1);
 581     }
 582
 583     flush_blks(f);
 584
 585     ret = qemu_file_get_error(f);
 586     if (ret) {
 587         blk_mig_cleanup(mon);
 588         return ret;
 589     }
 590
 591     blk_mig_reset_dirty_cursor();
 592
 593     if (stage == 2) {
 594         /* control the rate of transfer */
 595         while ((block_mig_state.submitted +
 596                 block_mig_state.read_done) * BLOCK_SIZE <
 597                qemu_file_get_rate_limit(f)) {
 598             if (block_mig_state.bulk_completed == 0) {
 599                 /* first finish the bulk phase */
 600                 if (blk_mig_save_bulked_block(mon, f) == 0) {
 601                     /* finished saving bulk on all devices */
 602                     block_mig_state.bulk_completed = 1;
 603                 }
 604             } else {
 605                 if (blk_mig_save_dirty_block(mon, f, 1) == 0) {
 606                     /* no more dirty blocks */
 607                     break;
 608                 }
 609             }
 610         }
 611
 612         flush_blks(f);
 613
 614         ret = qemu_file_get_error(f);
 615         if (ret) {
 616             blk_mig_cleanup(mon);
 617             return ret;
 618         }
 619     }
 620
 621     if (stage == 3) {
 622         /* we know for sure that save bulk is completed and
 623            all async read completed */
 624         assert(block_mig_state.submitted == 0);
 625
 626         while (blk_mig_save_dirty_block(mon, f, 0) != 0);
 627         blk_mig_cleanup(mon);
 628
 629         /* report completion */
 630         qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 631
 632         ret = qemu_file_get_error(f);
 633         if (ret) {
 634             return ret;
 635         }
 636
 637         monitor_printf(mon, "Block migration completed\n");
 638     }
 639
 640     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 641
 642     return ((stage == 2) && is_stage2_completed());
 643 }
 644
 645 static int block_load(QEMUFile *f, void *opaque, int version_id)
 646 {
 647     static int banner_printed;
 648     int len, flags;
 649     char device_name[256];
 650     int64_t addr;
 651     BlockDriverState *bs, *bs_prev = NULL;
 652     uint8_t *buf;
 653     int64_t total_sectors = 0;
 654     int nr_sectors;
 655     int ret;
 656
 657     do {
 658         addr = qemu_get_be64(f);
 659
 660         flags = addr & ~BDRV_SECTOR_MASK;
 661         addr >>= BDRV_SECTOR_BITS;
 662
 663         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 664             /* get device name */
 665             len = qemu_get_byte(f);
 666             qemu_get_buffer(f, (uint8_t *)device_name, len);
 667             device_name[len] = '\0';
 668
 669             bs = bdrv_find(device_name);
 670             if (!bs) {
 671                 fprintf(stderr, "Error unknown block device %s\n",
 672                         device_name);
 673                 return -EINVAL;
 674             }
 675
 676             if (bs != bs_prev) {
 677                 bs_prev = bs;
 678                 total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 679                 if (total_sectors <= 0) {
 680                     error_report("Error getting length of block device %s",
 681                                  device_name);
 682                     return -EINVAL;
 683                 }
 684             }
 685
 686             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 687                 nr_sectors = total_sectors - addr;
 688             } else {
 689                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 690             }
 691
 692             buf = g_malloc(BLOCK_SIZE);
 693
 694             qemu_get_buffer(f, buf, BLOCK_SIZE);
 695             ret = bdrv_write(bs, addr, buf, nr_sectors);
 696
 697             g_free(buf);
 698             if (ret < 0) {
 699                 return ret;
 700             }
 701         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 702             if (!banner_printed) {
 703                 printf("Receiving block device images\n");
 704                 banner_printed = 1;
 705             }
 706             printf("Completed %d %%%c", (int)addr,
 707                    (addr == 100) ? '\n' : '\r');
 708             fflush(stdout);
 709         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 710             fprintf(stderr, "Unknown flags\n");
 711             return -EINVAL;
 712         }
 713         ret = qemu_file_get_error(f);
 714         if (ret != 0) {
 715             return ret;
 716         }
 717     } while (!(flags & BLK_MIG_FLAG_EOS));
 718
 719     return 0;
 720 }
 721
 722 static void block_set_params(int blk_enable, int shared_base, void *opaque)
 723 {
 724     block_mig_state.blk_enable = blk_enable;
 725     block_mig_state.shared_base = shared_base;
 726
 727     /* shared base means that blk_enable = 1 */
 728     block_mig_state.blk_enable |= shared_base;
 729 }
 730
 731 void blk_mig_init(void)
 732 {
 733     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 734     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 735
 736     register_savevm_live(NULL, "block", 0, 1, block_set_params,
 737                          block_save_live, NULL, block_load, &block_mig_state);
 738 }