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 "block-migration.h"
  22 #include "migration.h"
  23 #include "blockdev.h"
  24 #include <assert.h>
  25
  26 #define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << BDRV_SECTOR_BITS)
  27
  28 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
  29 #define BLK_MIG_FLAG_EOS                0x02
  30 #define BLK_MIG_FLAG_PROGRESS           0x04
  31
  32 #define MAX_IS_ALLOCATED_SEARCH 65536
  33
  34 //#define DEBUG_BLK_MIGRATION
  35
  36 #ifdef DEBUG_BLK_MIGRATION
  37 #define DPRINTF(fmt, ...) \
  38     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
  39 #else
  40 #define DPRINTF(fmt, ...) \
  41     do { } while (0)
  42 #endif
  43
  44 typedef struct BlkMigDevState {
  45     BlockDriverState *bs;
  46     int bulk_completed;
  47     int shared_base;
  48     int64_t cur_sector;
  49     int64_t cur_dirty;
  50     int64_t completed_sectors;
  51     int64_t total_sectors;
  52     int64_t dirty;
  53     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  54     unsigned long *aio_bitmap;
  55 } BlkMigDevState;
  56
  57 typedef struct BlkMigBlock {
  58     uint8_t *buf;
  59     BlkMigDevState *bmds;
  60     int64_t sector;
  61     int nr_sectors;
  62     struct iovec iov;
  63     QEMUIOVector qiov;
  64     BlockDriverAIOCB *aiocb;
  65     int ret;
  66     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  67 } BlkMigBlock;
  68
  69 typedef struct BlkMigState {
  70     int blk_enable;
  71     int shared_base;
  72     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  73     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
  74     int submitted;
  75     int read_done;
  76     int transferred;
  77     int64_t total_sector_sum;
  78     int prev_progress;
  79     int bulk_completed;
  80     long double total_time;
  81     long double prev_time_offset;
  82     int reads;
  83 } BlkMigState;
  84
  85 static BlkMigState block_mig_state;
  86
  87 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
  88 {
  89     int len;
  90
  91     /* sector number and flags */
  92     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
  93                      | BLK_MIG_FLAG_DEVICE_BLOCK);
  94
  95     /* device name */
  96     len = strlen(blk->bmds->bs->device_name);
  97     qemu_put_byte(f, len);
  98     qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
  99
 100     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 101 }
 102
 103 int blk_mig_active(void)
 104 {
 105     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 106 }
 107
 108 uint64_t blk_mig_bytes_transferred(void)
 109 {
 110     BlkMigDevState *bmds;
 111     uint64_t sum = 0;
 112
 113     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 114         sum += bmds->completed_sectors;
 115     }
 116     return sum << BDRV_SECTOR_BITS;
 117 }
 118
 119 uint64_t blk_mig_bytes_remaining(void)
 120 {
 121     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 122 }
 123
 124 uint64_t blk_mig_bytes_total(void)
 125 {
 126     BlkMigDevState *bmds;
 127     uint64_t sum = 0;
 128
 129     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 130         sum += bmds->total_sectors;
 131     }
 132     return sum << BDRV_SECTOR_BITS;
 133 }
 134
 135 static inline long double compute_read_bwidth(void)
 136 {
 137     assert(block_mig_state.total_time != 0);
 138     return (block_mig_state.reads / block_mig_state.total_time) * BLOCK_SIZE;
 139 }
 140
 141 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
 142 {
 143     int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 144
 145     if ((sector << BDRV_SECTOR_BITS) < bdrv_getlength(bmds->bs)) {
 146         return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
 147             (1UL << (chunk % (sizeof(unsigned long) * 8))));
 148     } else {
 149         return 0;
 150     }
 151 }
 152
 153 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
 154                              int nb_sectors, int set)
 155 {
 156     int64_t start, end;
 157     unsigned long val, idx, bit;
 158
 159     start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
 160     end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
 161
 162     for (; start <= end; start++) {
 163         idx = start / (sizeof(unsigned long) * 8);
 164         bit = start % (sizeof(unsigned long) * 8);
 165         val = bmds->aio_bitmap[idx];
 166         if (set) {
 167             val |= 1UL << bit;
 168         } else {
 169             val &= ~(1UL << bit);
 170         }
 171         bmds->aio_bitmap[idx] = val;
 172     }
 173 }
 174
 175 static void alloc_aio_bitmap(BlkMigDevState *bmds)
 176 {
 177     BlockDriverState *bs = bmds->bs;
 178     int64_t bitmap_size;
 179
 180     bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
 181             BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
 182     bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 183
 184     bmds->aio_bitmap = g_malloc0(bitmap_size);
 185 }
 186
 187 static void blk_mig_read_cb(void *opaque, int ret)
 188 {
 189     long double curr_time = qemu_get_clock_ns(rt_clock);
 190     BlkMigBlock *blk = opaque;
 191
 192     blk->ret = ret;
 193
 194     block_mig_state.reads++;
 195     block_mig_state.total_time += (curr_time - block_mig_state.prev_time_offset);
 196     block_mig_state.prev_time_offset = curr_time;
 197
 198     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
 199     bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
 200
 201     block_mig_state.submitted--;
 202     block_mig_state.read_done++;
 203     assert(block_mig_state.submitted >= 0);
 204 }
 205
 206 static int mig_save_device_bulk(QEMUFile *f, 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     block_mig_state.submitted++;
 255
 256     bdrv_reset_dirty(bs, cur_sector, nr_sectors);
 257     bmds->cur_sector = cur_sector + nr_sectors;
 258
 259     return (bmds->cur_sector >= total_sectors);
 260 }
 261
 262 static void set_dirty_tracking(int enable)
 263 {
 264     BlkMigDevState *bmds;
 265
 266     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 267         bdrv_set_dirty_tracking(bmds->bs, enable);
 268     }
 269 }
 270
 271 static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
 272 {
 273     BlkMigDevState *bmds;
 274     int64_t sectors;
 275
 276     if (!bdrv_is_read_only(bs)) {
 277         sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 278         if (sectors <= 0) {
 279             return;
 280         }
 281
 282         bmds = g_malloc0(sizeof(BlkMigDevState));
 283         bmds->bs = bs;
 284         bmds->bulk_completed = 0;
 285         bmds->total_sectors = sectors;
 286         bmds->completed_sectors = 0;
 287         bmds->shared_base = block_mig_state.shared_base;
 288         alloc_aio_bitmap(bmds);
 289         drive_get_ref(drive_get_by_blockdev(bs));
 290         bdrv_set_in_use(bs, 1);
 291
 292         block_mig_state.total_sector_sum += sectors;
 293
 294         if (bmds->shared_base) {
 295             DPRINTF("Start migration for %s with shared base image\n",
 296                     bs->device_name);
 297         } else {
 298             DPRINTF("Start full migration for %s\n", bs->device_name);
 299         }
 300
 301         QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 302     }
 303 }
 304
 305 static void init_blk_migration(QEMUFile *f)
 306 {
 307     block_mig_state.submitted = 0;
 308     block_mig_state.read_done = 0;
 309     block_mig_state.transferred = 0;
 310     block_mig_state.total_sector_sum = 0;
 311     block_mig_state.prev_progress = -1;
 312     block_mig_state.bulk_completed = 0;
 313     block_mig_state.total_time = 0;
 314     block_mig_state.reads = 0;
 315
 316     bdrv_iterate(init_blk_migration_it, NULL);
 317 }
 318
 319 static int blk_mig_save_bulked_block(QEMUFile *f)
 320 {
 321     int64_t completed_sector_sum = 0;
 322     BlkMigDevState *bmds;
 323     int progress;
 324     int ret = 0;
 325
 326     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 327         if (bmds->bulk_completed == 0) {
 328             if (mig_save_device_bulk(f, bmds) == 1) {
 329                 /* completed bulk section for this device */
 330                 bmds->bulk_completed = 1;
 331             }
 332             completed_sector_sum += bmds->completed_sectors;
 333             ret = 1;
 334             break;
 335         } else {
 336             completed_sector_sum += bmds->completed_sectors;
 337         }
 338     }
 339
 340     if (block_mig_state.total_sector_sum != 0) {
 341         progress = completed_sector_sum * 100 /
 342                    block_mig_state.total_sector_sum;
 343     } else {
 344         progress = 100;
 345     }
 346     if (progress != block_mig_state.prev_progress) {
 347         block_mig_state.prev_progress = progress;
 348         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 349                          | BLK_MIG_FLAG_PROGRESS);
 350         DPRINTF("Completed %d %%\r", progress);
 351     }
 352
 353     return ret;
 354 }
 355
 356 static void blk_mig_reset_dirty_cursor(void)
 357 {
 358     BlkMigDevState *bmds;
 359
 360     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 361         bmds->cur_dirty = 0;
 362     }
 363 }
 364
 365 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
 366                                  int is_async)
 367 {
 368     BlkMigBlock *blk;
 369     int64_t total_sectors = bmds->total_sectors;
 370     int64_t sector;
 371     int nr_sectors;
 372     int ret = -EIO;
 373
 374     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 375         if (bmds_aio_inflight(bmds, sector)) {
 376             bdrv_drain_all();
 377         }
 378         if (bdrv_get_dirty(bmds->bs, sector)) {
 379
 380             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 381                 nr_sectors = total_sectors - sector;
 382             } else {
 383                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 384             }
 385             blk = g_malloc(sizeof(BlkMigBlock));
 386             blk->buf = g_malloc(BLOCK_SIZE);
 387             blk->bmds = bmds;
 388             blk->sector = sector;
 389             blk->nr_sectors = nr_sectors;
 390
 391             if (is_async) {
 392                 blk->iov.iov_base = blk->buf;
 393                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 394                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 395
 396                 if (block_mig_state.submitted == 0) {
 397                     block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
 398                 }
 399
 400                 blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
 401                                             nr_sectors, blk_mig_read_cb, blk);
 402                 block_mig_state.submitted++;
 403                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 404             } else {
 405                 ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
 406                 if (ret < 0) {
 407                     goto error;
 408                 }
 409                 blk_send(f, blk);
 410
 411                 g_free(blk->buf);
 412                 g_free(blk);
 413             }
 414
 415             bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
 416             break;
 417         }
 418         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 419         bmds->cur_dirty = sector;
 420     }
 421
 422     return (bmds->cur_dirty >= bmds->total_sectors);
 423
 424 error:
 425     DPRINTF("Error reading sector %" PRId64 "\n", sector);
 426     qemu_file_set_error(f, ret);
 427     g_free(blk->buf);
 428     g_free(blk);
 429     return 0;
 430 }
 431
 432 static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
 433 {
 434     BlkMigDevState *bmds;
 435     int ret = 0;
 436
 437     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 438         if (mig_save_device_dirty(f, bmds, is_async) == 0) {
 439             ret = 1;
 440             break;
 441         }
 442     }
 443
 444     return ret;
 445 }
 446
 447 static void flush_blks(QEMUFile* f)
 448 {
 449     BlkMigBlock *blk;
 450
 451     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 452             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 453             block_mig_state.transferred);
 454
 455     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 456         if (qemu_file_rate_limit(f)) {
 457             break;
 458         }
 459         if (blk->ret < 0) {
 460             qemu_file_set_error(f, blk->ret);
 461             break;
 462         }
 463         blk_send(f, blk);
 464
 465         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 466         g_free(blk->buf);
 467         g_free(blk);
 468
 469         block_mig_state.read_done--;
 470         block_mig_state.transferred++;
 471         assert(block_mig_state.read_done >= 0);
 472     }
 473
 474     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 475             block_mig_state.submitted, block_mig_state.read_done,
 476             block_mig_state.transferred);
 477 }
 478
 479 static int64_t get_remaining_dirty(void)
 480 {
 481     BlkMigDevState *bmds;
 482     int64_t dirty = 0;
 483
 484     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 485         dirty += bdrv_get_dirty_count(bmds->bs);
 486     }
 487
 488     return dirty * BLOCK_SIZE;
 489 }
 490
 491 static int is_stage2_completed(void)
 492 {
 493     int64_t remaining_dirty;
 494     long double bwidth;
 495
 496     if (block_mig_state.bulk_completed == 1) {
 497
 498         remaining_dirty = get_remaining_dirty();
 499         if (remaining_dirty == 0) {
 500             return 1;
 501         }
 502
 503         bwidth = compute_read_bwidth();
 504
 505         if ((remaining_dirty / bwidth) <=
 506             migrate_max_downtime()) {
 507             /* finish stage2 because we think that we can finish remaining work
 508                below max_downtime */
 509
 510             return 1;
 511         }
 512     }
 513
 514     return 0;
 515 }
 516
 517 static void blk_mig_cleanup(void)
 518 {
 519     BlkMigDevState *bmds;
 520     BlkMigBlock *blk;
 521
 522     set_dirty_tracking(0);
 523
 524     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 525         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 526         bdrv_set_in_use(bmds->bs, 0);
 527         drive_put_ref(drive_get_by_blockdev(bmds->bs));
 528         g_free(bmds->aio_bitmap);
 529         g_free(bmds);
 530     }
 531
 532     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 533         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 534         g_free(blk->buf);
 535         g_free(blk);
 536     }
 537 }
 538
 539 static void block_migration_cancel(void *opaque)
 540 {
 541     blk_mig_cleanup();
 542 }
 543
 544 static int block_save_setup(QEMUFile *f, void *opaque)
 545 {
 546     int ret;
 547
 548     DPRINTF("Enter save live setup submitted %d transferred %d\n",
 549             block_mig_state.submitted, block_mig_state.transferred);
 550
 551     init_blk_migration(f);
 552
 553     /* start track dirty blocks */
 554     set_dirty_tracking(1);
 555
 556     flush_blks(f);
 557
 558     ret = qemu_file_get_error(f);
 559     if (ret) {
 560         blk_mig_cleanup();
 561         return ret;
 562     }
 563
 564     blk_mig_reset_dirty_cursor();
 565
 566     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 567
 568     return 0;
 569 }
 570
 571 static int block_save_live(QEMUFile *f, int stage, void *opaque)
 572 {
 573     int ret;
 574
 575     DPRINTF("Enter save live stage %d submitted %d transferred %d\n",
 576             stage, block_mig_state.submitted, block_mig_state.transferred);
 577
 578     flush_blks(f);
 579
 580     ret = qemu_file_get_error(f);
 581     if (ret) {
 582         blk_mig_cleanup();
 583         return ret;
 584     }
 585
 586     blk_mig_reset_dirty_cursor();
 587
 588     if (stage == 2) {
 589         /* control the rate of transfer */
 590         while ((block_mig_state.submitted +
 591                 block_mig_state.read_done) * BLOCK_SIZE <
 592                qemu_file_get_rate_limit(f)) {
 593             if (block_mig_state.bulk_completed == 0) {
 594                 /* first finish the bulk phase */
 595                 if (blk_mig_save_bulked_block(f) == 0) {
 596                     /* finished saving bulk on all devices */
 597                     block_mig_state.bulk_completed = 1;
 598                 }
 599             } else {
 600                 if (blk_mig_save_dirty_block(f, 1) == 0) {
 601                     /* no more dirty blocks */
 602                     break;
 603                 }
 604             }
 605         }
 606
 607         flush_blks(f);
 608
 609         ret = qemu_file_get_error(f);
 610         if (ret) {
 611             blk_mig_cleanup();
 612             return ret;
 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(f, 0) != 0);
 622         blk_mig_cleanup();
 623
 624         /* report completion */
 625         qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 626
 627         ret = qemu_file_get_error(f);
 628         if (ret) {
 629             return ret;
 630         }
 631
 632         DPRINTF("Block migration completed\n");
 633     }
 634
 635     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 636
 637     return ((stage == 2) && is_stage2_completed());
 638 }
 639
 640 static int block_load(QEMUFile *f, void *opaque, int version_id)
 641 {
 642     static int banner_printed;
 643     int len, flags;
 644     char device_name[256];
 645     int64_t addr;
 646     BlockDriverState *bs, *bs_prev = NULL;
 647     uint8_t *buf;
 648     int64_t total_sectors = 0;
 649     int nr_sectors;
 650     int ret;
 651
 652     do {
 653         addr = qemu_get_be64(f);
 654
 655         flags = addr & ~BDRV_SECTOR_MASK;
 656         addr >>= BDRV_SECTOR_BITS;
 657
 658         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 659             /* get device name */
 660             len = qemu_get_byte(f);
 661             qemu_get_buffer(f, (uint8_t *)device_name, len);
 662             device_name[len] = '\0';
 663
 664             bs = bdrv_find(device_name);
 665             if (!bs) {
 666                 fprintf(stderr, "Error unknown block device %s\n",
 667                         device_name);
 668                 return -EINVAL;
 669             }
 670
 671             if (bs != bs_prev) {
 672                 bs_prev = bs;
 673                 total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 674                 if (total_sectors <= 0) {
 675                     error_report("Error getting length of block device %s",
 676                                  device_name);
 677                     return -EINVAL;
 678                 }
 679             }
 680
 681             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 682                 nr_sectors = total_sectors - addr;
 683             } else {
 684                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 685             }
 686
 687             buf = g_malloc(BLOCK_SIZE);
 688
 689             qemu_get_buffer(f, buf, BLOCK_SIZE);
 690             ret = bdrv_write(bs, addr, buf, nr_sectors);
 691
 692             g_free(buf);
 693             if (ret < 0) {
 694                 return ret;
 695             }
 696         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 697             if (!banner_printed) {
 698                 printf("Receiving block device images\n");
 699                 banner_printed = 1;
 700             }
 701             printf("Completed %d %%%c", (int)addr,
 702                    (addr == 100) ? '\n' : '\r');
 703             fflush(stdout);
 704         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 705             fprintf(stderr, "Unknown flags\n");
 706             return -EINVAL;
 707         }
 708         ret = qemu_file_get_error(f);
 709         if (ret != 0) {
 710             return ret;
 711         }
 712     } while (!(flags & BLK_MIG_FLAG_EOS));
 713
 714     return 0;
 715 }
 716
 717 static void block_set_params(const MigrationParams *params, void *opaque)
 718 {
 719     block_mig_state.blk_enable = params->blk;
 720     block_mig_state.shared_base = params->shared;
 721
 722     /* shared base means that blk_enable = 1 */
 723     block_mig_state.blk_enable |= params->shared;
 724 }
 725
 726 static bool block_is_active(void *opaque)
 727 {
 728     return block_mig_state.blk_enable == 1;
 729 }
 730
 731 SaveVMHandlers savevm_block_handlers = {
 732     .set_params = block_set_params,
 733     .save_live_setup = block_save_setup,
 734     .save_live_state = block_save_live,
 735     .load_state = block_load,
 736     .cancel = block_migration_cancel,
 737     .is_active = block_is_active,
 738 };
 739
 740 void blk_mig_init(void)
 741 {
 742     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 743     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 744
 745     register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
 746                          &block_mig_state);
 747 }