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