migration/block.c

   1 /*
   2  * QEMU live block migration
   3  *
   4  * Copyright IBM, Corp. 2009
   5  *
   6  * Authors:
   7  *  Liran Schour   <[email protected]>
   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/osdep.h"
  17 #include "qapi/error.h"
  18 #include "qemu/error-report.h"
  19 #include "qemu/cutils.h"
  20 #include "qemu/queue.h"
  21 #include "block.h"
  22 #include "migration/misc.h"
  23 #include "migration.h"
  24 #include "migration/register.h"
  25 #include "qemu-file.h"
  26 #include "migration/vmstate.h"
  27 #include "sysemu/block-backend.h"
  28
  29 #define BLOCK_SIZE                       (1 << 20)
  30 #define BDRV_SECTORS_PER_DIRTY_CHUNK     (BLOCK_SIZE >> BDRV_SECTOR_BITS)
  31
  32 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01
  33 #define BLK_MIG_FLAG_EOS                0x02
  34 #define BLK_MIG_FLAG_PROGRESS           0x04
  35 #define BLK_MIG_FLAG_ZERO_BLOCK         0x08
  36
  37 #define MAX_IS_ALLOCATED_SEARCH (65536 * BDRV_SECTOR_SIZE)
  38
  39 #define MAX_IO_BUFFERS 512
  40 #define MAX_PARALLEL_IO 16
  41
  42 //#define DEBUG_BLK_MIGRATION
  43
  44 #ifdef DEBUG_BLK_MIGRATION
  45 #define DPRINTF(fmt, ...) \
  46     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
  47 #else
  48 #define DPRINTF(fmt, ...) \
  49     do { } while (0)
  50 #endif
  51
  52 typedef struct BlkMigDevState {
  53     /* Written during setup phase.  Can be read without a lock.  */
  54     BlockBackend *blk;
  55     char *blk_name;
  56     int shared_base;
  57     int64_t total_sectors;
  58     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
  59     Error *blocker;
  60
  61     /* Only used by migration thread.  Does not need a lock.  */
  62     int bulk_completed;
  63     int64_t cur_sector;
  64     int64_t cur_dirty;
  65
  66     /* Data in the aio_bitmap is protected by block migration lock.
  67      * Allocation and free happen during setup and cleanup respectively.
  68      */
  69     unsigned long *aio_bitmap;
  70
  71     /* Protected by block migration lock.  */
  72     int64_t completed_sectors;
  73
  74     /* During migration this is protected by iothread lock / AioContext.
  75      * Allocation and free happen during setup and cleanup respectively.
  76      */
  77     BdrvDirtyBitmap *dirty_bitmap;
  78 } BlkMigDevState;
  79
  80 typedef struct BlkMigBlock {
  81     /* Only used by migration thread.  */
  82     uint8_t *buf;
  83     BlkMigDevState *bmds;
  84     int64_t sector;
  85     int nr_sectors;
  86     struct iovec iov;
  87     QEMUIOVector qiov;
  88     BlockAIOCB *aiocb;
  89
  90     /* Protected by block migration lock.  */
  91     int ret;
  92     QSIMPLEQ_ENTRY(BlkMigBlock) entry;
  93 } BlkMigBlock;
  94
  95 typedef struct BlkMigState {
  96     QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
  97     int64_t total_sector_sum;
  98     bool zero_blocks;
  99
 100     /* Protected by lock.  */
 101     QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
 102     int submitted;
 103     int read_done;
 104
 105     /* Only used by migration thread.  Does not need a lock.  */
 106     int transferred;
 107     int prev_progress;
 108     int bulk_completed;
 109
 110     /* Lock must be taken _inside_ the iothread lock and any AioContexts.  */
 111     QemuMutex lock;
 112 } BlkMigState;
 113
 114 static BlkMigState block_mig_state;
 115
 116 static void blk_mig_lock(void)
 117 {
 118     qemu_mutex_lock(&block_mig_state.lock);
 119 }
 120
 121 static void blk_mig_unlock(void)
 122 {
 123     qemu_mutex_unlock(&block_mig_state.lock);
 124 }
 125
 126 /* Must run outside of the iothread lock during the bulk phase,
 127  * or the VM will stall.
 128  */
 129
 130 static void blk_send(QEMUFile *f, BlkMigBlock * blk)
 131 {
 132     int len;
 133     uint64_t flags = BLK_MIG_FLAG_DEVICE_BLOCK;
 134
 135     if (block_mig_state.zero_blocks &&
 136         buffer_is_zero(blk->buf, BLOCK_SIZE)) {
 137         flags |= BLK_MIG_FLAG_ZERO_BLOCK;
 138     }
 139
 140     /* sector number and flags */
 141     qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
 142                      | flags);
 143
 144     /* device name */
 145     len = strlen(blk->bmds->blk_name);
 146     qemu_put_byte(f, len);
 147     qemu_put_buffer(f, (uint8_t *) blk->bmds->blk_name, len);
 148
 149     /* if a block is zero we need to flush here since the network
 150      * bandwidth is now a lot higher than the storage device bandwidth.
 151      * thus if we queue zero blocks we slow down the migration */
 152     if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
 153         qemu_fflush(f);
 154         return;
 155     }
 156
 157     qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 158 }
 159
 160 int blk_mig_active(void)
 161 {
 162     return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
 163 }
 164
 165 int blk_mig_bulk_active(void)
 166 {
 167     return blk_mig_active() && !block_mig_state.bulk_completed;
 168 }
 169
 170 uint64_t blk_mig_bytes_transferred(void)
 171 {
 172     BlkMigDevState *bmds;
 173     uint64_t sum = 0;
 174
 175     blk_mig_lock();
 176     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 177         sum += bmds->completed_sectors;
 178     }
 179     blk_mig_unlock();
 180     return sum << BDRV_SECTOR_BITS;
 181 }
 182
 183 uint64_t blk_mig_bytes_remaining(void)
 184 {
 185     return blk_mig_bytes_total() - blk_mig_bytes_transferred();
 186 }
 187
 188 uint64_t blk_mig_bytes_total(void)
 189 {
 190     BlkMigDevState *bmds;
 191     uint64_t sum = 0;
 192
 193     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 194         sum += bmds->total_sectors;
 195     }
 196     return sum << BDRV_SECTOR_BITS;
 197 }
 198
 199
 200 /* Called with migration lock held.  */
 201
 202 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
 203 {
 204     int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 205
 206     if (sector < blk_nb_sectors(bmds->blk)) {
 207         return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
 208             (1UL << (chunk % (sizeof(unsigned long) * 8))));
 209     } else {
 210         return 0;
 211     }
 212 }
 213
 214 /* Called with migration lock held.  */
 215
 216 static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
 217                              int nb_sectors, int set)
 218 {
 219     int64_t start, end;
 220     unsigned long val, idx, bit;
 221
 222     start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
 223     end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
 224
 225     for (; start <= end; start++) {
 226         idx = start / (sizeof(unsigned long) * 8);
 227         bit = start % (sizeof(unsigned long) * 8);
 228         val = bmds->aio_bitmap[idx];
 229         if (set) {
 230             val |= 1UL << bit;
 231         } else {
 232             val &= ~(1UL << bit);
 233         }
 234         bmds->aio_bitmap[idx] = val;
 235     }
 236 }
 237
 238 static void alloc_aio_bitmap(BlkMigDevState *bmds)
 239 {
 240     BlockBackend *bb = bmds->blk;
 241     int64_t bitmap_size;
 242
 243     bitmap_size = blk_nb_sectors(bb) + BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
 244     bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 245
 246     bmds->aio_bitmap = g_malloc0(bitmap_size);
 247 }
 248
 249 /* Never hold migration lock when yielding to the main loop!  */
 250
 251 static void blk_mig_read_cb(void *opaque, int ret)
 252 {
 253     BlkMigBlock *blk = opaque;
 254
 255     blk_mig_lock();
 256     blk->ret = ret;
 257
 258     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
 259     bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
 260
 261     block_mig_state.submitted--;
 262     block_mig_state.read_done++;
 263     assert(block_mig_state.submitted >= 0);
 264     blk_mig_unlock();
 265 }
 266
 267 /* Called with no lock taken.  */
 268
 269 static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
 270 {
 271     int64_t total_sectors = bmds->total_sectors;
 272     int64_t cur_sector = bmds->cur_sector;
 273     BlockBackend *bb = bmds->blk;
 274     BlkMigBlock *blk;
 275     int nr_sectors;
 276     int64_t count;
 277
 278     if (bmds->shared_base) {
 279         qemu_mutex_lock_iothread();
 280         aio_context_acquire(blk_get_aio_context(bb));
 281         /* Skip unallocated sectors; intentionally treats failure or
 282          * partial sector as an allocated sector */
 283         while (cur_sector < total_sectors &&
 284                !bdrv_is_allocated(blk_bs(bb), cur_sector * BDRV_SECTOR_SIZE,
 285                                   MAX_IS_ALLOCATED_SEARCH, &count)) {
 286             if (count < BDRV_SECTOR_SIZE) {
 287                 break;
 288             }
 289             cur_sector += count >> BDRV_SECTOR_BITS;
 290         }
 291         aio_context_release(blk_get_aio_context(bb));
 292         qemu_mutex_unlock_iothread();
 293     }
 294
 295     if (cur_sector >= total_sectors) {
 296         bmds->cur_sector = bmds->completed_sectors = total_sectors;
 297         return 1;
 298     }
 299
 300     bmds->completed_sectors = cur_sector;
 301
 302     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 303
 304     /* we are going to transfer a full block even if it is not allocated */
 305     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 306
 307     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 308         nr_sectors = total_sectors - cur_sector;
 309     }
 310
 311     blk = g_new(BlkMigBlock, 1);
 312     blk->buf = g_malloc(BLOCK_SIZE);
 313     blk->bmds = bmds;
 314     blk->sector = cur_sector;
 315     blk->nr_sectors = nr_sectors;
 316
 317     blk->iov.iov_base = blk->buf;
 318     blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 319     qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 320
 321     blk_mig_lock();
 322     block_mig_state.submitted++;
 323     blk_mig_unlock();
 324
 325     /* We do not know if bs is under the main thread (and thus does
 326      * not acquire the AioContext when doing AIO) or rather under
 327      * dataplane.  Thus acquire both the iothread mutex and the
 328      * AioContext.
 329      *
 330      * This is ugly and will disappear when we make bdrv_* thread-safe,
 331      * without the need to acquire the AioContext.
 332      */
 333     qemu_mutex_lock_iothread();
 334     aio_context_acquire(blk_get_aio_context(bmds->blk));
 335     bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, cur_sector * BDRV_SECTOR_SIZE,
 336                             nr_sectors * BDRV_SECTOR_SIZE);
 337     blk->aiocb = blk_aio_preadv(bb, cur_sector * BDRV_SECTOR_SIZE, &blk->qiov,
 338                                 0, blk_mig_read_cb, blk);
 339     aio_context_release(blk_get_aio_context(bmds->blk));
 340     qemu_mutex_unlock_iothread();
 341
 342     bmds->cur_sector = cur_sector + nr_sectors;
 343     return (bmds->cur_sector >= total_sectors);
 344 }
 345
 346 /* Called with iothread lock taken.  */
 347
 348 static int set_dirty_tracking(void)
 349 {
 350     BlkMigDevState *bmds;
 351     int ret;
 352
 353     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 354         bmds->dirty_bitmap = bdrv_create_dirty_bitmap(blk_bs(bmds->blk),
 355                                                       BLOCK_SIZE, NULL, NULL);
 356         if (!bmds->dirty_bitmap) {
 357             ret = -errno;
 358             goto fail;
 359         }
 360     }
 361     return 0;
 362
 363 fail:
 364     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 365         if (bmds->dirty_bitmap) {
 366             bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);
 367         }
 368     }
 369     return ret;
 370 }
 371
 372 /* Called with iothread lock taken.  */
 373
 374 static void unset_dirty_tracking(void)
 375 {
 376     BlkMigDevState *bmds;
 377
 378     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 379         bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);
 380     }
 381 }
 382
 383 static int init_blk_migration(QEMUFile *f)
 384 {
 385     BlockDriverState *bs;
 386     BlkMigDevState *bmds;
 387     int64_t sectors;
 388     BdrvNextIterator it;
 389     int i, num_bs = 0;
 390     struct {
 391         BlkMigDevState *bmds;
 392         BlockDriverState *bs;
 393     } *bmds_bs;
 394     Error *local_err = NULL;
 395     int ret;
 396
 397     block_mig_state.submitted = 0;
 398     block_mig_state.read_done = 0;
 399     block_mig_state.transferred = 0;
 400     block_mig_state.total_sector_sum = 0;
 401     block_mig_state.prev_progress = -1;
 402     block_mig_state.bulk_completed = 0;
 403     block_mig_state.zero_blocks = migrate_zero_blocks();
 404
 405     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
 406         num_bs++;
 407     }
 408     bmds_bs = g_malloc0(num_bs * sizeof(*bmds_bs));
 409
 410     for (i = 0, bs = bdrv_first(&it); bs; bs = bdrv_next(&it), i++) {
 411         if (bdrv_is_read_only(bs)) {
 412             continue;
 413         }
 414
 415         sectors = bdrv_nb_sectors(bs);
 416         if (sectors <= 0) {
 417             ret = sectors;
 418             bdrv_next_cleanup(&it);
 419             goto out;
 420         }
 421
 422         bmds = g_new0(BlkMigDevState, 1);
 423         bmds->blk = blk_new(BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
 424         bmds->blk_name = g_strdup(bdrv_get_device_name(bs));
 425         bmds->bulk_completed = 0;
 426         bmds->total_sectors = sectors;
 427         bmds->completed_sectors = 0;
 428         bmds->shared_base = migrate_use_block_incremental();
 429
 430         assert(i < num_bs);
 431         bmds_bs[i].bmds = bmds;
 432         bmds_bs[i].bs = bs;
 433
 434         block_mig_state.total_sector_sum += sectors;
 435
 436         if (bmds->shared_base) {
 437             DPRINTF("Start migration for %s with shared base image\n",
 438                     bdrv_get_device_name(bs));
 439         } else {
 440             DPRINTF("Start full migration for %s\n", bdrv_get_device_name(bs));
 441         }
 442
 443         QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
 444     }
 445
 446     /* Can only insert new BDSes now because doing so while iterating block
 447      * devices may end up in a deadlock (iterating the new BDSes, too). */
 448     for (i = 0; i < num_bs; i++) {
 449         BlkMigDevState *bmds = bmds_bs[i].bmds;
 450         BlockDriverState *bs = bmds_bs[i].bs;
 451
 452         if (bmds) {
 453             ret = blk_insert_bs(bmds->blk, bs, &local_err);
 454             if (ret < 0) {
 455                 error_report_err(local_err);
 456                 goto out;
 457             }
 458
 459             alloc_aio_bitmap(bmds);
 460             error_setg(&bmds->blocker, "block device is in use by migration");
 461             bdrv_op_block_all(bs, bmds->blocker);
 462         }
 463     }
 464
 465     ret = 0;
 466 out:
 467     g_free(bmds_bs);
 468     return ret;
 469 }
 470
 471 /* Called with no lock taken.  */
 472
 473 static int blk_mig_save_bulked_block(QEMUFile *f)
 474 {
 475     int64_t completed_sector_sum = 0;
 476     BlkMigDevState *bmds;
 477     int progress;
 478     int ret = 0;
 479
 480     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 481         if (bmds->bulk_completed == 0) {
 482             if (mig_save_device_bulk(f, bmds) == 1) {
 483                 /* completed bulk section for this device */
 484                 bmds->bulk_completed = 1;
 485             }
 486             completed_sector_sum += bmds->completed_sectors;
 487             ret = 1;
 488             break;
 489         } else {
 490             completed_sector_sum += bmds->completed_sectors;
 491         }
 492     }
 493
 494     if (block_mig_state.total_sector_sum != 0) {
 495         progress = completed_sector_sum * 100 /
 496                    block_mig_state.total_sector_sum;
 497     } else {
 498         progress = 100;
 499     }
 500     if (progress != block_mig_state.prev_progress) {
 501         block_mig_state.prev_progress = progress;
 502         qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
 503                          | BLK_MIG_FLAG_PROGRESS);
 504         DPRINTF("Completed %d %%\r", progress);
 505     }
 506
 507     return ret;
 508 }
 509
 510 static void blk_mig_reset_dirty_cursor(void)
 511 {
 512     BlkMigDevState *bmds;
 513
 514     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 515         bmds->cur_dirty = 0;
 516     }
 517 }
 518
 519 /* Called with iothread lock and AioContext taken.  */
 520
 521 static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
 522                                  int is_async)
 523 {
 524     BlkMigBlock *blk;
 525     BlockDriverState *bs = blk_bs(bmds->blk);
 526     int64_t total_sectors = bmds->total_sectors;
 527     int64_t sector;
 528     int nr_sectors;
 529     int ret = -EIO;
 530
 531     for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
 532         blk_mig_lock();
 533         if (bmds_aio_inflight(bmds, sector)) {
 534             blk_mig_unlock();
 535             blk_drain(bmds->blk);
 536         } else {
 537             blk_mig_unlock();
 538         }
 539         bdrv_dirty_bitmap_lock(bmds->dirty_bitmap);
 540         if (bdrv_get_dirty_locked(bs, bmds->dirty_bitmap,
 541                                   sector * BDRV_SECTOR_SIZE)) {
 542             if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 543                 nr_sectors = total_sectors - sector;
 544             } else {
 545                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 546             }
 547             bdrv_reset_dirty_bitmap_locked(bmds->dirty_bitmap,
 548                                            sector * BDRV_SECTOR_SIZE,
 549                                            nr_sectors * BDRV_SECTOR_SIZE);
 550             bdrv_dirty_bitmap_unlock(bmds->dirty_bitmap);
 551
 552             blk = g_new(BlkMigBlock, 1);
 553             blk->buf = g_malloc(BLOCK_SIZE);
 554             blk->bmds = bmds;
 555             blk->sector = sector;
 556             blk->nr_sectors = nr_sectors;
 557
 558             if (is_async) {
 559                 blk->iov.iov_base = blk->buf;
 560                 blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
 561                 qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
 562
 563                 blk->aiocb = blk_aio_preadv(bmds->blk,
 564                                             sector * BDRV_SECTOR_SIZE,
 565                                             &blk->qiov, 0, blk_mig_read_cb,
 566                                             blk);
 567
 568                 blk_mig_lock();
 569                 block_mig_state.submitted++;
 570                 bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
 571                 blk_mig_unlock();
 572             } else {
 573                 ret = blk_pread(bmds->blk, sector * BDRV_SECTOR_SIZE, blk->buf,
 574                                 nr_sectors * BDRV_SECTOR_SIZE);
 575                 if (ret < 0) {
 576                     goto error;
 577                 }
 578                 blk_send(f, blk);
 579
 580                 g_free(blk->buf);
 581                 g_free(blk);
 582             }
 583
 584             sector += nr_sectors;
 585             bmds->cur_dirty = sector;
 586             break;
 587         }
 588
 589         bdrv_dirty_bitmap_unlock(bmds->dirty_bitmap);
 590         sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
 591         bmds->cur_dirty = sector;
 592     }
 593
 594     return (bmds->cur_dirty >= bmds->total_sectors);
 595
 596 error:
 597     DPRINTF("Error reading sector %" PRId64 "\n", sector);
 598     g_free(blk->buf);
 599     g_free(blk);
 600     return ret;
 601 }
 602
 603 /* Called with iothread lock taken.
 604  *
 605  * return value:
 606  * 0: too much data for max_downtime
 607  * 1: few enough data for max_downtime
 608 */
 609 static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
 610 {
 611     BlkMigDevState *bmds;
 612     int ret = 1;
 613
 614     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 615         aio_context_acquire(blk_get_aio_context(bmds->blk));
 616         ret = mig_save_device_dirty(f, bmds, is_async);
 617         aio_context_release(blk_get_aio_context(bmds->blk));
 618         if (ret <= 0) {
 619             break;
 620         }
 621     }
 622
 623     return ret;
 624 }
 625
 626 /* Called with no locks taken.  */
 627
 628 static int flush_blks(QEMUFile *f)
 629 {
 630     BlkMigBlock *blk;
 631     int ret = 0;
 632
 633     DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
 634             __func__, block_mig_state.submitted, block_mig_state.read_done,
 635             block_mig_state.transferred);
 636
 637     blk_mig_lock();
 638     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 639         if (qemu_file_rate_limit(f)) {
 640             break;
 641         }
 642         if (blk->ret < 0) {
 643             ret = blk->ret;
 644             break;
 645         }
 646
 647         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 648         blk_mig_unlock();
 649         blk_send(f, blk);
 650         blk_mig_lock();
 651
 652         g_free(blk->buf);
 653         g_free(blk);
 654
 655         block_mig_state.read_done--;
 656         block_mig_state.transferred++;
 657         assert(block_mig_state.read_done >= 0);
 658     }
 659     blk_mig_unlock();
 660
 661     DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __func__,
 662             block_mig_state.submitted, block_mig_state.read_done,
 663             block_mig_state.transferred);
 664     return ret;
 665 }
 666
 667 /* Called with iothread lock taken.  */
 668
 669 static int64_t get_remaining_dirty(void)
 670 {
 671     BlkMigDevState *bmds;
 672     int64_t dirty = 0;
 673
 674     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
 675         aio_context_acquire(blk_get_aio_context(bmds->blk));
 676         dirty += bdrv_get_dirty_count(bmds->dirty_bitmap);
 677         aio_context_release(blk_get_aio_context(bmds->blk));
 678     }
 679
 680     return dirty;
 681 }
 682
 683
 684
 685 /* Called with iothread lock taken.  */
 686 static void block_migration_cleanup_bmds(void)
 687 {
 688     BlkMigDevState *bmds;
 689     AioContext *ctx;
 690
 691     unset_dirty_tracking();
 692
 693     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
 694         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
 695         bdrv_op_unblock_all(blk_bs(bmds->blk), bmds->blocker);
 696         error_free(bmds->blocker);
 697
 698         /* Save ctx, because bmds->blk can disappear during blk_unref.  */
 699         ctx = blk_get_aio_context(bmds->blk);
 700         aio_context_acquire(ctx);
 701         blk_unref(bmds->blk);
 702         aio_context_release(ctx);
 703
 704         g_free(bmds->blk_name);
 705         g_free(bmds->aio_bitmap);
 706         g_free(bmds);
 707     }
 708 }
 709
 710 /* Called with iothread lock taken.  */
 711 static void block_migration_cleanup(void *opaque)
 712 {
 713     BlkMigBlock *blk;
 714
 715     bdrv_drain_all();
 716
 717     block_migration_cleanup_bmds();
 718
 719     blk_mig_lock();
 720     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
 721         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
 722         g_free(blk->buf);
 723         g_free(blk);
 724     }
 725     blk_mig_unlock();
 726 }
 727
 728 static int block_save_setup(QEMUFile *f, void *opaque)
 729 {
 730     int ret;
 731
 732     DPRINTF("Enter save live setup submitted %d transferred %d\n",
 733             block_mig_state.submitted, block_mig_state.transferred);
 734
 735     qemu_mutex_lock_iothread();
 736     ret = init_blk_migration(f);
 737     if (ret < 0) {
 738         qemu_mutex_unlock_iothread();
 739         return ret;
 740     }
 741
 742     /* start track dirty blocks */
 743     ret = set_dirty_tracking();
 744
 745     qemu_mutex_unlock_iothread();
 746
 747     if (ret) {
 748         return ret;
 749     }
 750
 751     ret = flush_blks(f);
 752     blk_mig_reset_dirty_cursor();
 753     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 754
 755     return ret;
 756 }
 757
 758 static int block_save_iterate(QEMUFile *f, void *opaque)
 759 {
 760     int ret;
 761     int64_t last_ftell = qemu_ftell(f);
 762     int64_t delta_ftell;
 763
 764     DPRINTF("Enter save live iterate submitted %d transferred %d\n",
 765             block_mig_state.submitted, block_mig_state.transferred);
 766
 767     ret = flush_blks(f);
 768     if (ret) {
 769         return ret;
 770     }
 771
 772     blk_mig_reset_dirty_cursor();
 773
 774     /* control the rate of transfer */
 775     blk_mig_lock();
 776     while (block_mig_state.read_done * BLOCK_SIZE <
 777            qemu_file_get_rate_limit(f) &&
 778            block_mig_state.submitted < MAX_PARALLEL_IO &&
 779            (block_mig_state.submitted + block_mig_state.read_done) <
 780            MAX_IO_BUFFERS) {
 781         blk_mig_unlock();
 782         if (block_mig_state.bulk_completed == 0) {
 783             /* first finish the bulk phase */
 784             if (blk_mig_save_bulked_block(f) == 0) {
 785                 /* finished saving bulk on all devices */
 786                 block_mig_state.bulk_completed = 1;
 787             }
 788             ret = 0;
 789         } else {
 790             /* Always called with iothread lock taken for
 791              * simplicity, block_save_complete also calls it.
 792              */
 793             qemu_mutex_lock_iothread();
 794             ret = blk_mig_save_dirty_block(f, 1);
 795             qemu_mutex_unlock_iothread();
 796         }
 797         if (ret < 0) {
 798             return ret;
 799         }
 800         blk_mig_lock();
 801         if (ret != 0) {
 802             /* no more dirty blocks */
 803             break;
 804         }
 805     }
 806     blk_mig_unlock();
 807
 808     ret = flush_blks(f);
 809     if (ret) {
 810         return ret;
 811     }
 812
 813     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 814     delta_ftell = qemu_ftell(f) - last_ftell;
 815     if (delta_ftell > 0) {
 816         return 1;
 817     } else if (delta_ftell < 0) {
 818         return -1;
 819     } else {
 820         return 0;
 821     }
 822 }
 823
 824 /* Called with iothread lock taken.  */
 825
 826 static int block_save_complete(QEMUFile *f, void *opaque)
 827 {
 828     int ret;
 829
 830     DPRINTF("Enter save live complete submitted %d transferred %d\n",
 831             block_mig_state.submitted, block_mig_state.transferred);
 832
 833     ret = flush_blks(f);
 834     if (ret) {
 835         return ret;
 836     }
 837
 838     blk_mig_reset_dirty_cursor();
 839
 840     /* we know for sure that save bulk is completed and
 841        all async read completed */
 842     blk_mig_lock();
 843     assert(block_mig_state.submitted == 0);
 844     blk_mig_unlock();
 845
 846     do {
 847         ret = blk_mig_save_dirty_block(f, 0);
 848         if (ret < 0) {
 849             return ret;
 850         }
 851     } while (ret == 0);
 852
 853     /* report completion */
 854     qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
 855
 856     DPRINTF("Block migration completed\n");
 857
 858     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
 859
 860     /* Make sure that our BlockBackends are gone, so that the block driver
 861      * nodes can be inactivated. */
 862     block_migration_cleanup_bmds();
 863
 864     return 0;
 865 }
 866
 867 static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
 868                                uint64_t *res_precopy_only,
 869                                uint64_t *res_compatible,
 870                                uint64_t *res_postcopy_only)
 871 {
 872     /* Estimate pending number of bytes to send */
 873     uint64_t pending;
 874
 875     qemu_mutex_lock_iothread();
 876     pending = get_remaining_dirty();
 877     qemu_mutex_unlock_iothread();
 878
 879     blk_mig_lock();
 880     pending += block_mig_state.submitted * BLOCK_SIZE +
 881                block_mig_state.read_done * BLOCK_SIZE;
 882     blk_mig_unlock();
 883
 884     /* Report at least one block pending during bulk phase */
 885     if (pending <= max_size && !block_mig_state.bulk_completed) {
 886         pending = max_size + BLOCK_SIZE;
 887     }
 888
 889     DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
 890     /* We don't do postcopy */
 891     *res_precopy_only += pending;
 892 }
 893
 894 static int block_load(QEMUFile *f, void *opaque, int version_id)
 895 {
 896     static int banner_printed;
 897     int len, flags;
 898     char device_name[256];
 899     int64_t addr;
 900     BlockBackend *blk, *blk_prev = NULL;
 901     Error *local_err = NULL;
 902     uint8_t *buf;
 903     int64_t total_sectors = 0;
 904     int nr_sectors;
 905     int ret;
 906     BlockDriverInfo bdi;
 907     int cluster_size = BLOCK_SIZE;
 908
 909     do {
 910         addr = qemu_get_be64(f);
 911
 912         flags = addr & ~BDRV_SECTOR_MASK;
 913         addr >>= BDRV_SECTOR_BITS;
 914
 915         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
 916             /* get device name */
 917             len = qemu_get_byte(f);
 918             qemu_get_buffer(f, (uint8_t *)device_name, len);
 919             device_name[len] = '\0';
 920
 921             blk = blk_by_name(device_name);
 922             if (!blk) {
 923                 fprintf(stderr, "Error unknown block device %s\n",
 924                         device_name);
 925                 return -EINVAL;
 926             }
 927
 928             if (blk != blk_prev) {
 929                 blk_prev = blk;
 930                 total_sectors = blk_nb_sectors(blk);
 931                 if (total_sectors <= 0) {
 932                     error_report("Error getting length of block device %s",
 933                                  device_name);
 934                     return -EINVAL;
 935                 }
 936
 937                 blk_invalidate_cache(blk, &local_err);
 938                 if (local_err) {
 939                     error_report_err(local_err);
 940                     return -EINVAL;
 941                 }
 942
 943                 ret = bdrv_get_info(blk_bs(blk), &bdi);
 944                 if (ret == 0 && bdi.cluster_size > 0 &&
 945                     bdi.cluster_size <= BLOCK_SIZE &&
 946                     BLOCK_SIZE % bdi.cluster_size == 0) {
 947                     cluster_size = bdi.cluster_size;
 948                 } else {
 949                     cluster_size = BLOCK_SIZE;
 950                 }
 951             }
 952
 953             if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
 954                 nr_sectors = total_sectors - addr;
 955             } else {
 956                 nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 957             }
 958
 959             if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
 960                 ret = blk_pwrite_zeroes(blk, addr * BDRV_SECTOR_SIZE,
 961                                         nr_sectors * BDRV_SECTOR_SIZE,
 962                                         BDRV_REQ_MAY_UNMAP);
 963             } else {
 964                 int i;
 965                 int64_t cur_addr;
 966                 uint8_t *cur_buf;
 967
 968                 buf = g_malloc(BLOCK_SIZE);
 969                 qemu_get_buffer(f, buf, BLOCK_SIZE);
 970                 for (i = 0; i < BLOCK_SIZE / cluster_size; i++) {
 971                     cur_addr = addr * BDRV_SECTOR_SIZE + i * cluster_size;
 972                     cur_buf = buf + i * cluster_size;
 973
 974                     if ((!block_mig_state.zero_blocks ||
 975                         cluster_size < BLOCK_SIZE) &&
 976                         buffer_is_zero(cur_buf, cluster_size)) {
 977                         ret = blk_pwrite_zeroes(blk, cur_addr,
 978                                                 cluster_size,
 979                                                 BDRV_REQ_MAY_UNMAP);
 980                     } else {
 981                         ret = blk_pwrite(blk, cur_addr, cur_buf,
 982                                          cluster_size, 0);
 983                     }
 984                     if (ret < 0) {
 985                         break;
 986                     }
 987                 }
 988                 g_free(buf);
 989             }
 990
 991             if (ret < 0) {
 992                 return ret;
 993             }
 994         } else if (flags & BLK_MIG_FLAG_PROGRESS) {
 995             if (!banner_printed) {
 996                 printf("Receiving block device images\n");
 997                 banner_printed = 1;
 998             }
 999             printf("Completed %d %%%c", (int)addr,
1000                    (addr == 100) ? '\n' : '\r');
1001             fflush(stdout);
1002         } else if (!(flags & BLK_MIG_FLAG_EOS)) {
1003             fprintf(stderr, "Unknown block migration flags: %#x\n", flags);
1004             return -EINVAL;
1005         }
1006         ret = qemu_file_get_error(f);
1007         if (ret != 0) {
1008             return ret;
1009         }
1010     } while (!(flags & BLK_MIG_FLAG_EOS));
1011
1012     return 0;
1013 }
1014
1015 static bool block_is_active(void *opaque)
1016 {
1017     return migrate_use_block();
1018 }
1019
1020 static SaveVMHandlers savevm_block_handlers = {
1021     .save_setup = block_save_setup,
1022     .save_live_iterate = block_save_iterate,
1023     .save_live_complete_precopy = block_save_complete,
1024     .save_live_pending = block_save_pending,
1025     .load_state = block_load,
1026     .save_cleanup = block_migration_cleanup,
1027     .is_active = block_is_active,
1028 };
1029
1030 void blk_mig_init(void)
1031 {
1032     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
1033     QSIMPLEQ_INIT(&block_mig_state.blk_list);
1034     qemu_mutex_init(&block_mig_state.lock);
1035
1036     register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
1037                          &block_mig_state);
1038 }