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/block_int.h"
  18 #include "hw/hw.h"
  19 #include "qemu/queue.h"
  20 #include "qemu/timer.h"
  21 #include "migration/block.h"
  22 #include "migration/migration.h"
  23 #include "sysemu/blockdev.h"
  24 #include <assert.h>
  25
  26 #define BLOCK_SIZE                       (1 << 20)
  27 #define BDRV_SECTORS_PER_DIRTY_CHUNK     (BLOCK_SIZE >> 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     /* Written during setup phase.  Can be read without a lock.  */
  47     BlockDriverState *bs;
  48     int shared_base;
  49     int64_t total_sectors;
  50     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  51
  52     /* Only used by migration thread.  Does not need a lock.  */
  53     int bulk_completed;
  54     int64_t cur_sector;
  55     int64_t cur_dirty;
  56
  57     /* Protected by iothread lock.  */
  58     unsigned long *aio_bitmap;
  59     int64_t completed_sectors;
  60 } BlkMigDevState;
  61
  62 typedef struct BlkMigBlock {
  63     /* Only used by migration thread.  */
  64     uint8_t *buf;
  65     BlkMigDevState *bmds;
  66     int64_t sector;
  67     int nr_sectors;
  68     struct iovec iov;
  69     QEMUIOVector qiov;
  70     BlockDriverAIOCB *aiocb;
  71
  72     /* Protected by iothread lock.  */
  73     int ret;
  74     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  75 } BlkMigBlock;
  76
  77 typedef struct BlkMigState {
  78     /* Written during setup phase.  Can be read without a lock.  */
  79     int blk_enable;
  80     int shared_base;
  81     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  82     int64_t total_sector_sum;
  83
  84     /* Protected by iothread lock.  */
  85     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
  86     int submitted;
  87     int read_done;
  88
  89     /* Only used by migration thread.  Does not need a lock.  */
  90     int transferred;
  91     int prev_progress;
  92     int bulk_completed;
  93 } BlkMigState;
  94
  95 static BlkMigState block_mig_state;
  96
  97 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
  98 {
  99     int len;
 100
 101     /* sector number and flags */
 102     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
 103                      | BLK_MIG_FLAG_DEVICE_BLOCK);
 104
 105     /* device name */
 106     len = strlen(blk->bmds->bs->device_name);
 107     qemu_put_byte(f, len);
 108     qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
 109
 110     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 111 }
 112
 113 int blk_mig_active(void)
 114 {
 115     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 116 }
 117
 118 uint64_t blk_mig_bytes_transferred(void)
 119 {
 120     BlkMigDevState *bmds;
 121     uint64_t sum = 0;
 122
 123     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 124         sum += bmds->completed_sectors;
 125     }
 126     return sum << BDRV_SECTOR_BITS;
 127 }
 128
 129 uint64_t blk_mig_bytes_remaining(void)
 130 {
 131     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 132 }
 133
 134 uint64_t blk_mig_bytes_total(void)
 135 {
 136     BlkMigDevState *bmds;
 137     uint64_t sum = 0;
 138
 139     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 140         sum += bmds->total_sectors;
 141     }
 142     return sum << BDRV_SECTOR_BITS;
 143 }
 144
 145 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
 146 {
 147     int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 148
 149     if ((sector << BDRV_SECTOR_BITS) < bdrv_getlength(bmds->bs)) {
 150         return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
 151             (1UL << (chunk % (sizeof(unsigned long) * 8))));
 152     } else {
 153         return 0;
 154     }
 155 }
 156
 157 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
 158                              int nb_sectors, int set)
 159 {
 160     int64_t start, end;
 161     unsigned long val, idx, bit;
 162
 163     start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
 164     end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
 165
 166     for (; start <= end; start++) {
 167         idx = start / (sizeof(unsigned long) * 8);
 168         bit = start % (sizeof(unsigned long) * 8);
 169         val = bmds->aio_bitmap[idx];
 170         if (set) {
 171             val |= 1UL << bit;
 172         } else {
 173             val &= ~(1UL << bit);
 174         }
 175         bmds->aio_bitmap[idx] = val;
 176     }
 177 }
 178
 179 static void alloc_aio_bitmap(BlkMigDevState *bmds)
 180 {
 181     BlockDriverState *bs = bmds->bs;
 182     int64_t bitmap_size;
 183
 184     bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
 185             BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
 186     bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 187
 188     bmds->aio_bitmap = g_malloc0(bitmap_size);
 189 }
 190
 191 static void blk_mig_read_cb(void *opaque, int ret)
 192 {
 193     BlkMigBlock *blk = opaque;
 194
 195     blk->ret = ret;
 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(QEMUFile *f, BlkMigDevState *bmds)
 206 {
 207     int64_t total_sectors = bmds->total_sectors;
 208     int64_t cur_sector = bmds->cur_sector;
 209     BlockDriverState *bs = bmds->bs;
 210     BlkMigBlock *blk;
 211     int nr_sectors;
 212
 213     if (bmds->shared_base) {
 214         while (cur_sector < total_sectors &&
 215                !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
 216                                   &nr_sectors)) {
 217             cur_sector += nr_sectors;
 218         }
 219     }
 220
 221     if (cur_sector >= total_sectors) {
 222         bmds->cur_sector = bmds->completed_sectors = total_sectors;
 223         return 1;
 224     }
 225
 226     bmds->completed_sectors = cur_sector;
 227
 228     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 229
 230     /* we are going to transfer a full block even if it is not allocated */
 231     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 232
 233     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 234         nr_sectors = total_sectors - cur_sector;
 235     }
 236
 237     blk = g_malloc(sizeof(BlkMigBlock));
 238     blk->buf = g_malloc(BLOCK_SIZE);
 239     blk->bmds = bmds;
 240     blk->sector = cur_sector;
 241     blk->nr_sectors = nr_sectors;
 242
 243     blk->iov.iov_base = blk->buf;
 244     blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 245     qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 246
 247     block_mig_state.submitted++;
 248
 249     blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
 250                                 nr_sectors, blk_mig_read_cb, blk);
 251
 252     bdrv_reset_dirty(bs, cur_sector, nr_sectors);
 253     bmds->cur_sector = cur_sector + nr_sectors;
 254
 255     return (bmds->cur_sector >= total_sectors);
 256 }
 257
 258 static void set_dirty_tracking(int enable)
 259 {
 260     BlkMigDevState *bmds;
 261
 262     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 263         bdrv_set_dirty_tracking(bmds->bs, enable ? BLOCK_SIZE : 0);
 264     }
 265 }
 266
 267 static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
 268 {
 269     BlkMigDevState *bmds;
 270     int64_t sectors;
 271
 272     if (!bdrv_is_read_only(bs)) {
 273         sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 274         if (sectors <= 0) {
 275             return;
 276         }
 277
 278         bmds = g_malloc0(sizeof(BlkMigDevState));
 279         bmds->bs = bs;
 280         bmds->bulk_completed = 0;
 281         bmds->total_sectors = sectors;
 282         bmds->completed_sectors = 0;
 283         bmds->shared_base = block_mig_state.shared_base;
 284         alloc_aio_bitmap(bmds);
 285         drive_get_ref(drive_get_by_blockdev(bs));
 286         bdrv_set_in_use(bs, 1);
 287
 288         block_mig_state.total_sector_sum += sectors;
 289
 290         if (bmds->shared_base) {
 291             DPRINTF("Start migration for %s with shared base image\n",
 292                     bs->device_name);
 293         } else {
 294             DPRINTF("Start full migration for %s\n", bs->device_name);
 295         }
 296
 297         QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 298     }
 299 }
 300
 301 static void init_blk_migration(QEMUFile *f)
 302 {
 303     block_mig_state.submitted = 0;
 304     block_mig_state.read_done = 0;
 305     block_mig_state.transferred = 0;
 306     block_mig_state.total_sector_sum = 0;
 307     block_mig_state.prev_progress = -1;
 308     block_mig_state.bulk_completed = 0;
 309
 310     bdrv_iterate(init_blk_migration_it, NULL);
 311 }
 312
 313 static int blk_mig_save_bulked_block(QEMUFile *f)
 314 {
 315     int64_t completed_sector_sum = 0;
 316     BlkMigDevState *bmds;
 317     int progress;
 318     int ret = 0;
 319
 320     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 321         if (bmds->bulk_completed == 0) {
 322             if (mig_save_device_bulk(f, bmds) == 1) {
 323                 /* completed bulk section for this device */
 324                 bmds->bulk_completed = 1;
 325             }
 326             completed_sector_sum += bmds->completed_sectors;
 327             ret = 1;
 328             break;
 329         } else {
 330             completed_sector_sum += bmds->completed_sectors;
 331         }
 332     }
 333
 334     if (block_mig_state.total_sector_sum != 0) {
 335         progress = completed_sector_sum * 100 /
 336                    block_mig_state.total_sector_sum;
 337     } else {
 338         progress = 100;
 339     }
 340     if (progress != block_mig_state.prev_progress) {
 341         block_mig_state.prev_progress = progress;
 342         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 343                          | BLK_MIG_FLAG_PROGRESS);
 344         DPRINTF("Completed %d %%\r", progress);
 345     }
 346
 347     return ret;
 348 }
 349
 350 static void blk_mig_reset_dirty_cursor(void)
 351 {
 352     BlkMigDevState *bmds;
 353
 354     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 355         bmds->cur_dirty = 0;
 356     }
 357 }
 358
 359 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
 360                                  int is_async)
 361 {
 362     BlkMigBlock *blk;
 363     int64_t total_sectors = bmds->total_sectors;
 364     int64_t sector;
 365     int nr_sectors;
 366     int ret = -EIO;
 367
 368     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 369         if (bmds_aio_inflight(bmds, sector)) {
 370             bdrv_drain_all();
 371         }
 372         if (bdrv_get_dirty(bmds->bs, sector)) {
 373
 374             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 375                 nr_sectors = total_sectors - sector;
 376             } else {
 377                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 378             }
 379             blk = g_malloc(sizeof(BlkMigBlock));
 380             blk->buf = g_malloc(BLOCK_SIZE);
 381             blk->bmds = bmds;
 382             blk->sector = sector;
 383             blk->nr_sectors = nr_sectors;
 384
 385             if (is_async) {
 386                 blk->iov.iov_base = blk->buf;
 387                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 388                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 389
 390                 blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
 391                                             nr_sectors, blk_mig_read_cb, blk);
 392                 block_mig_state.submitted++;
 393                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 394             } else {
 395                 ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
 396                 if (ret < 0) {
 397                     goto error;
 398                 }
 399                 blk_send(f, blk);
 400
 401                 g_free(blk->buf);
 402                 g_free(blk);
 403             }
 404
 405             bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
 406             break;
 407         }
 408         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 409         bmds->cur_dirty = sector;
 410     }
 411
 412     return (bmds->cur_dirty >= bmds->total_sectors);
 413
 414 error:
 415     DPRINTF("Error reading sector %" PRId64 "\n", sector);
 416     g_free(blk->buf);
 417     g_free(blk);
 418     return ret;
 419 }
 420
 421 /* return value:
 422  * 0: too much data for max_downtime
 423  * 1: few enough data for max_downtime
 424 */
 425 static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
 426 {
 427     BlkMigDevState *bmds;
 428     int ret = 1;
 429
 430     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 431         ret = mig_save_device_dirty(f, bmds, is_async);
 432         if (ret <= 0) {
 433             break;
 434         }
 435     }
 436
 437     return ret;
 438 }
 439
 440 static int flush_blks(QEMUFile *f)
 441 {
 442     BlkMigBlock *blk;
 443     int ret = 0;
 444
 445     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 446             __FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
 447             block_mig_state.transferred);
 448
 449     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 450         if (qemu_file_rate_limit(f)) {
 451             break;
 452         }
 453         if (blk->ret < 0) {
 454             ret = blk->ret;
 455             break;
 456         }
 457
 458         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 459         blk_send(f, blk);
 460
 461         g_free(blk->buf);
 462         g_free(blk);
 463
 464         block_mig_state.read_done--;
 465         block_mig_state.transferred++;
 466         assert(block_mig_state.read_done >= 0);
 467     }
 468
 469     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
 470             block_mig_state.submitted, block_mig_state.read_done,
 471             block_mig_state.transferred);
 472     return ret;
 473 }
 474
 475 static int64_t get_remaining_dirty(void)
 476 {
 477     BlkMigDevState *bmds;
 478     int64_t dirty = 0;
 479
 480     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 481         dirty += bdrv_get_dirty_count(bmds->bs);
 482     }
 483
 484     return dirty << BDRV_SECTOR_BITS;
 485 }
 486
 487 static void blk_mig_cleanup(void)
 488 {
 489     BlkMigDevState *bmds;
 490     BlkMigBlock *blk;
 491
 492     bdrv_drain_all();
 493
 494     set_dirty_tracking(0);
 495
 496     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 497         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 498         bdrv_set_in_use(bmds->bs, 0);
 499         drive_put_ref(drive_get_by_blockdev(bmds->bs));
 500         g_free(bmds->aio_bitmap);
 501         g_free(bmds);
 502     }
 503
 504     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 505         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 506         g_free(blk->buf);
 507         g_free(blk);
 508     }
 509 }
 510
 511 static void block_migration_cancel(void *opaque)
 512 {
 513     blk_mig_cleanup();
 514 }
 515
 516 static int block_save_setup(QEMUFile *f, void *opaque)
 517 {
 518     int ret;
 519
 520     DPRINTF("Enter save live setup submitted %d transferred %d\n",
 521             block_mig_state.submitted, block_mig_state.transferred);
 522
 523     init_blk_migration(f);
 524
 525     /* start track dirty blocks */
 526     set_dirty_tracking(1);
 527
 528     ret = flush_blks(f);
 529     blk_mig_reset_dirty_cursor();
 530     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 531
 532     return ret;
 533 }
 534
 535 static int block_save_iterate(QEMUFile *f, void *opaque)
 536 {
 537     int ret;
 538     int64_t last_ftell = qemu_ftell(f);
 539
 540     DPRINTF("Enter save live iterate submitted %d transferred %d\n",
 541             block_mig_state.submitted, block_mig_state.transferred);
 542
 543     ret = flush_blks(f);
 544     if (ret) {
 545         return ret;
 546     }
 547
 548     blk_mig_reset_dirty_cursor();
 549
 550     /* control the rate of transfer */
 551     while ((block_mig_state.submitted +
 552             block_mig_state.read_done) * BLOCK_SIZE <
 553            qemu_file_get_rate_limit(f)) {
 554         if (block_mig_state.bulk_completed == 0) {
 555             /* first finish the bulk phase */
 556             if (blk_mig_save_bulked_block(f) == 0) {
 557                 /* finished saving bulk on all devices */
 558                 block_mig_state.bulk_completed = 1;
 559             }
 560             ret = 0;
 561         } else {
 562             ret = blk_mig_save_dirty_block(f, 1);
 563         }
 564         if (ret < 0) {
 565             return ret;
 566         }
 567         if (ret != 0) {
 568             /* no more dirty blocks */
 569             break;
 570         }
 571     }
 572
 573     ret = flush_blks(f);
 574     if (ret) {
 575         return ret;
 576     }
 577
 578     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 579     return qemu_ftell(f) - last_ftell;
 580 }
 581
 582 static int block_save_complete(QEMUFile *f, void *opaque)
 583 {
 584     int ret;
 585
 586     DPRINTF("Enter save live complete submitted %d transferred %d\n",
 587             block_mig_state.submitted, block_mig_state.transferred);
 588
 589     ret = flush_blks(f);
 590     if (ret) {
 591         return ret;
 592     }
 593
 594     blk_mig_reset_dirty_cursor();
 595
 596     /* we know for sure that save bulk is completed and
 597        all async read completed */
 598     assert(block_mig_state.submitted == 0);
 599
 600     do {
 601         ret = blk_mig_save_dirty_block(f, 0);
 602         if (ret < 0) {
 603             return ret;
 604         }
 605     } while (ret == 0);
 606
 607     /* report completion */
 608     qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 609
 610     DPRINTF("Block migration completed\n");
 611
 612     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 613
 614     blk_mig_cleanup();
 615     return 0;
 616 }
 617
 618 static uint64_t block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
 619 {
 620     /* Estimate pending number of bytes to send */
 621     uint64_t pending;
 622
 623     pending = get_remaining_dirty() +
 624                        block_mig_state.submitted * BLOCK_SIZE +
 625                        block_mig_state.read_done * BLOCK_SIZE;
 626
 627     /* Report at least one block pending during bulk phase */
 628     if (pending == 0 && !block_mig_state.bulk_completed) {
 629         pending = BLOCK_SIZE;
 630     }
 631
 632     DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
 633     return pending;
 634 }
 635
 636 static int block_load(QEMUFile *f, void *opaque, int version_id)
 637 {
 638     static int banner_printed;
 639     int len, flags;
 640     char device_name[256];
 641     int64_t addr;
 642     BlockDriverState *bs, *bs_prev = NULL;
 643     uint8_t *buf;
 644     int64_t total_sectors = 0;
 645     int nr_sectors;
 646     int ret;
 647
 648     do {
 649         addr = qemu_get_be64(f);
 650
 651         flags = addr & ~BDRV_SECTOR_MASK;
 652         addr >>= BDRV_SECTOR_BITS;
 653
 654         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 655             /* get device name */
 656             len = qemu_get_byte(f);
 657             qemu_get_buffer(f, (uint8_t *)device_name, len);
 658             device_name[len] = '\0';
 659
 660             bs = bdrv_find(device_name);
 661             if (!bs) {
 662                 fprintf(stderr, "Error unknown block device %s\n",
 663                         device_name);
 664                 return -EINVAL;
 665             }
 666
 667             if (bs != bs_prev) {
 668                 bs_prev = bs;
 669                 total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
 670                 if (total_sectors <= 0) {
 671                     error_report("Error getting length of block device %s",
 672                                  device_name);
 673                     return -EINVAL;
 674                 }
 675             }
 676
 677             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 678                 nr_sectors = total_sectors - addr;
 679             } else {
 680                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 681             }
 682
 683             buf = g_malloc(BLOCK_SIZE);
 684
 685             qemu_get_buffer(f, buf, BLOCK_SIZE);
 686             ret = bdrv_write(bs, addr, buf, nr_sectors);
 687
 688             g_free(buf);
 689             if (ret < 0) {
 690                 return ret;
 691             }
 692         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 693             if (!banner_printed) {
 694                 printf("Receiving block device images\n");
 695                 banner_printed = 1;
 696             }
 697             printf("Completed %d %%%c", (int)addr,
 698                    (addr == 100) ? '\n' : '\r');
 699             fflush(stdout);
 700         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
 701             fprintf(stderr, "Unknown block migration flags: %#x\n", flags);
 702             return -EINVAL;
 703         }
 704         ret = qemu_file_get_error(f);
 705         if (ret != 0) {
 706             return ret;
 707         }
 708     } while (!(flags & BLK_MIG_FLAG_EOS));
 709
 710     return 0;
 711 }
 712
 713 static void block_set_params(const MigrationParams *params, void *opaque)
 714 {
 715     block_mig_state.blk_enable = params->blk;
 716     block_mig_state.shared_base = params->shared;
 717
 718     /* shared base means that blk_enable = 1 */
 719     block_mig_state.blk_enable |= params->shared;
 720 }
 721
 722 static bool block_is_active(void *opaque)
 723 {
 724     return block_mig_state.blk_enable == 1;
 725 }
 726
 727 SaveVMHandlers savevm_block_handlers = {
 728     .set_params = block_set_params,
 729     .save_live_setup = block_save_setup,
 730     .save_live_iterate = block_save_iterate,
 731     .save_live_complete = block_save_complete,
 732     .save_live_pending = block_save_pending,
 733     .load_state = block_load,
 734     .cancel = block_migration_cancel,
 735     .is_active = block_is_active,
 736 };
 737
 738 void blk_mig_init(void)
 739 {
 740     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
 741     QSIMPLEQ_INIT(&block_mig_state.blk_list);
 742
 743     register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
 744                          &block_mig_state);
 745 }