block/block-copy.c

   1 /*
   2  * block_copy API
   3  *
   4  * Copyright (C) 2013 Proxmox Server Solutions
   5  * Copyright (c) 2019 Virtuozzo International GmbH.
   6  *
   7  * Authors:
   8  *  Dietmar Maurer (dietmar@proxmox.com)
   9  *  Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  12  * See the COPYING file in the top-level directory.
  13  */
  14
  15 #include "qemu/osdep.h"
  16
  17 #include "trace.h"
  18 #include "qapi/error.h"
  19 #include "block/block-copy.h"
  20 #include "sysemu/block-backend.h"
  21 #include "qemu/units.h"
  22 #include "qemu/coroutine.h"
  23 #include "block/aio_task.h"
  24
  25 #define BLOCK_COPY_MAX_COPY_RANGE (16 * MiB)
  26 #define BLOCK_COPY_MAX_BUFFER (1 * MiB)
  27 #define BLOCK_COPY_MAX_MEM (128 * MiB)
  28 #define BLOCK_COPY_MAX_WORKERS 64
  29 #define BLOCK_COPY_SLICE_TIME 100000000ULL /* ns */
  30
  31 static coroutine_fn int block_copy_task_entry(AioTask *task);
  32
  33 typedef struct BlockCopyCallState {
  34     /* IN parameters. Initialized in block_copy_async() and never changed. */
  35     BlockCopyState *s;
  36     int64_t offset;
  37     int64_t bytes;
  38     int max_workers;
  39     int64_t max_chunk;
  40     bool ignore_ratelimit;
  41     BlockCopyAsyncCallbackFunc cb;
  42     void *cb_opaque;
  43
  44     /* Coroutine where async block-copy is running */
  45     Coroutine *co;
  46
  47     /* To reference all call states from BlockCopyState */
  48     QLIST_ENTRY(BlockCopyCallState) list;
  49
  50     /* State */
  51     int ret;
  52     bool finished;
  53     QemuCoSleep sleep;
  54     bool cancelled;
  55
  56     /* OUT parameters */
  57     bool error_is_read;
  58 } BlockCopyCallState;
  59
  60 typedef struct BlockCopyTask {
  61     AioTask task;
  62
  63     BlockCopyState *s;
  64     BlockCopyCallState *call_state;
  65     int64_t offset;
  66     int64_t bytes;
  67     bool zeroes;
  68     bool copy_range;
  69     QLIST_ENTRY(BlockCopyTask) list;
  70     CoQueue wait_queue; /* coroutines blocked on this task */
  71 } BlockCopyTask;
  72
  73 static int64_t task_end(BlockCopyTask *task)
  74 {
  75     return task->offset + task->bytes;
  76 }
  77
  78 typedef struct BlockCopyState {
  79     /*
  80      * BdrvChild objects are not owned or managed by block-copy. They are
  81      * provided by block-copy user and user is responsible for appropriate
  82      * permissions on these children.
  83      */
  84     BdrvChild *source;
  85     BdrvChild *target;
  86     BdrvDirtyBitmap *copy_bitmap;
  87     int64_t in_flight_bytes;
  88     int64_t cluster_size;
  89     bool use_copy_range;
  90     int64_t copy_size;
  91     uint64_t len;
  92     QLIST_HEAD(, BlockCopyTask) tasks; /* All tasks from all block-copy calls */
  93     QLIST_HEAD(, BlockCopyCallState) calls;
  94
  95     BdrvRequestFlags write_flags;
  96
  97     /*
  98      * skip_unallocated:
  99      *
 100      * Used by sync=top jobs, which first scan the source node for unallocated
 101      * areas and clear them in the copy_bitmap.  During this process, the bitmap
 102      * is thus not fully initialized: It may still have bits set for areas that
 103      * are unallocated and should actually not be copied.
 104      *
 105      * This is indicated by skip_unallocated.
 106      *
 107      * In this case, block_copy() will query the source’s allocation status,
 108      * skip unallocated regions, clear them in the copy_bitmap, and invoke
 109      * block_copy_reset_unallocated() every time it does.
 110      */
 111     bool skip_unallocated;
 112
 113     ProgressMeter *progress;
 114
 115     SharedResource *mem;
 116
 117     RateLimit rate_limit;
 118 } BlockCopyState;
 119
 120 static BlockCopyTask *find_conflicting_task(BlockCopyState *s,
 121                                             int64_t offset, int64_t bytes)
 122 {
 123     BlockCopyTask *t;
 124
 125     QLIST_FOREACH(t, &s->tasks, list) {
 126         if (offset + bytes > t->offset && offset < t->offset + t->bytes) {
 127             return t;
 128         }
 129     }
 130
 131     return NULL;
 132 }
 133
 134 /*
 135  * If there are no intersecting tasks return false. Otherwise, wait for the
 136  * first found intersecting tasks to finish and return true.
 137  */
 138 static bool coroutine_fn block_copy_wait_one(BlockCopyState *s, int64_t offset,
 139                                              int64_t bytes)
 140 {
 141     BlockCopyTask *task = find_conflicting_task(s, offset, bytes);
 142
 143     if (!task) {
 144         return false;
 145     }
 146
 147     qemu_co_queue_wait(&task->wait_queue, NULL);
 148
 149     return true;
 150 }
 151
 152 /*
 153  * Search for the first dirty area in offset/bytes range and create task at
 154  * the beginning of it.
 155  */
 156 static BlockCopyTask *block_copy_task_create(BlockCopyState *s,
 157                                              BlockCopyCallState *call_state,
 158                                              int64_t offset, int64_t bytes)
 159 {
 160     BlockCopyTask *task;
 161     int64_t max_chunk = MIN_NON_ZERO(s->copy_size, call_state->max_chunk);
 162
 163     if (!bdrv_dirty_bitmap_next_dirty_area(s->copy_bitmap,
 164                                            offset, offset + bytes,
 165                                            max_chunk, &offset, &bytes))
 166     {
 167         return NULL;
 168     }
 169
 170     assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
 171     bytes = QEMU_ALIGN_UP(bytes, s->cluster_size);
 172
 173     /* region is dirty, so no existent tasks possible in it */
 174     assert(!find_conflicting_task(s, offset, bytes));
 175
 176     bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes);
 177     s->in_flight_bytes += bytes;
 178
 179     task = g_new(BlockCopyTask, 1);
 180     *task = (BlockCopyTask) {
 181         .task.func = block_copy_task_entry,
 182         .s = s,
 183         .call_state = call_state,
 184         .offset = offset,
 185         .bytes = bytes,
 186         .copy_range = s->use_copy_range,
 187     };
 188     qemu_co_queue_init(&task->wait_queue);
 189     QLIST_INSERT_HEAD(&s->tasks, task, list);
 190
 191     return task;
 192 }
 193
 194 /*
 195  * block_copy_task_shrink
 196  *
 197  * Drop the tail of the task to be handled later. Set dirty bits back and
 198  * wake up all tasks waiting for us (may be some of them are not intersecting
 199  * with shrunk task)
 200  */
 201 static void coroutine_fn block_copy_task_shrink(BlockCopyTask *task,
 202                                                 int64_t new_bytes)
 203 {
 204     if (new_bytes == task->bytes) {
 205         return;
 206     }
 207
 208     assert(new_bytes > 0 && new_bytes < task->bytes);
 209
 210     task->s->in_flight_bytes -= task->bytes - new_bytes;
 211     bdrv_set_dirty_bitmap(task->s->copy_bitmap,
 212                           task->offset + new_bytes, task->bytes - new_bytes);
 213
 214     task->bytes = new_bytes;
 215     qemu_co_queue_restart_all(&task->wait_queue);
 216 }
 217
 218 static void coroutine_fn block_copy_task_end(BlockCopyTask *task, int ret)
 219 {
 220     task->s->in_flight_bytes -= task->bytes;
 221     if (ret < 0) {
 222         bdrv_set_dirty_bitmap(task->s->copy_bitmap, task->offset, task->bytes);
 223     }
 224     QLIST_REMOVE(task, list);
 225     qemu_co_queue_restart_all(&task->wait_queue);
 226 }
 227
 228 void block_copy_state_free(BlockCopyState *s)
 229 {
 230     if (!s) {
 231         return;
 232     }
 233
 234     ratelimit_destroy(&s->rate_limit);
 235     bdrv_release_dirty_bitmap(s->copy_bitmap);
 236     shres_destroy(s->mem);
 237     g_free(s);
 238 }
 239
 240 static uint32_t block_copy_max_transfer(BdrvChild *source, BdrvChild *target)
 241 {
 242     return MIN_NON_ZERO(INT_MAX,
 243                         MIN_NON_ZERO(source->bs->bl.max_transfer,
 244                                      target->bs->bl.max_transfer));
 245 }
 246
 247 BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
 248                                      int64_t cluster_size, bool use_copy_range,
 249                                      BdrvRequestFlags write_flags, Error **errp)
 250 {
 251     BlockCopyState *s;
 252     BdrvDirtyBitmap *copy_bitmap;
 253
 254     copy_bitmap = bdrv_create_dirty_bitmap(source->bs, cluster_size, NULL,
 255                                            errp);
 256     if (!copy_bitmap) {
 257         return NULL;
 258     }
 259     bdrv_disable_dirty_bitmap(copy_bitmap);
 260
 261     s = g_new(BlockCopyState, 1);
 262     *s = (BlockCopyState) {
 263         .source = source,
 264         .target = target,
 265         .copy_bitmap = copy_bitmap,
 266         .cluster_size = cluster_size,
 267         .len = bdrv_dirty_bitmap_size(copy_bitmap),
 268         .write_flags = write_flags,
 269         .mem = shres_create(BLOCK_COPY_MAX_MEM),
 270     };
 271
 272     if (block_copy_max_transfer(source, target) < cluster_size) {
 273         /*
 274          * copy_range does not respect max_transfer. We don't want to bother
 275          * with requests smaller than block-copy cluster size, so fallback to
 276          * buffered copying (read and write respect max_transfer on their
 277          * behalf).
 278          */
 279         s->use_copy_range = false;
 280         s->copy_size = cluster_size;
 281     } else if (write_flags & BDRV_REQ_WRITE_COMPRESSED) {
 282         /* Compression supports only cluster-size writes and no copy-range. */
 283         s->use_copy_range = false;
 284         s->copy_size = cluster_size;
 285     } else {
 286         /*
 287          * We enable copy-range, but keep small copy_size, until first
 288          * successful copy_range (look at block_copy_do_copy).
 289          */
 290         s->use_copy_range = use_copy_range;
 291         s->copy_size = MAX(s->cluster_size, BLOCK_COPY_MAX_BUFFER);
 292     }
 293
 294     ratelimit_init(&s->rate_limit);
 295     QLIST_INIT(&s->tasks);
 296     QLIST_INIT(&s->calls);
 297
 298     return s;
 299 }
 300
 301 void block_copy_set_progress_meter(BlockCopyState *s, ProgressMeter *pm)
 302 {
 303     s->progress = pm;
 304 }
 305
 306 /*
 307  * Takes ownership of @task
 308  *
 309  * If pool is NULL directly run the task, otherwise schedule it into the pool.
 310  *
 311  * Returns: task.func return code if pool is NULL
 312  *          otherwise -ECANCELED if pool status is bad
 313  *          otherwise 0 (successfully scheduled)
 314  */
 315 static coroutine_fn int block_copy_task_run(AioTaskPool *pool,
 316                                             BlockCopyTask *task)
 317 {
 318     if (!pool) {
 319         int ret = task->task.func(&task->task);
 320
 321         g_free(task);
 322         return ret;
 323     }
 324
 325     aio_task_pool_wait_slot(pool);
 326     if (aio_task_pool_status(pool) < 0) {
 327         co_put_to_shres(task->s->mem, task->bytes);
 328         block_copy_task_end(task, -ECANCELED);
 329         g_free(task);
 330         return -ECANCELED;
 331     }
 332
 333     aio_task_pool_start_task(pool, &task->task);
 334
 335     return 0;
 336 }
 337
 338 /*
 339  * block_copy_do_copy
 340  *
 341  * Do copy of cluster-aligned chunk. Requested region is allowed to exceed
 342  * s->len only to cover last cluster when s->len is not aligned to clusters.
 343  *
 344  * No sync here: nor bitmap neighter intersecting requests handling, only copy.
 345  *
 346  * @copy_range is an in-out argument: if *copy_range is false, copy_range is not
 347  * done. If *copy_range is true, copy_range is attempted. If the copy_range
 348  * attempt fails, the function falls back to the usual read+write and
 349  * *copy_range is set to false. *copy_range and zeroes must not be true
 350  * simultaneously.
 351  *
 352  * Returns 0 on success.
 353  */
 354 static int coroutine_fn block_copy_do_copy(BlockCopyState *s,
 355                                            int64_t offset, int64_t bytes,
 356                                            bool zeroes, bool *copy_range,
 357                                            bool *error_is_read)
 358 {
 359     int ret;
 360     int64_t nbytes = MIN(offset + bytes, s->len) - offset;
 361     void *bounce_buffer = NULL;
 362
 363     assert(offset >= 0 && bytes > 0 && INT64_MAX - offset >= bytes);
 364     assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
 365     assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
 366     assert(offset < s->len);
 367     assert(offset + bytes <= s->len ||
 368            offset + bytes == QEMU_ALIGN_UP(s->len, s->cluster_size));
 369     assert(nbytes < INT_MAX);
 370     assert(!(*copy_range && zeroes));
 371
 372     if (zeroes) {
 373         ret = bdrv_co_pwrite_zeroes(s->target, offset, nbytes, s->write_flags &
 374                                     ~BDRV_REQ_WRITE_COMPRESSED);
 375         if (ret < 0) {
 376             trace_block_copy_write_zeroes_fail(s, offset, ret);
 377             *error_is_read = false;
 378         }
 379         return ret;
 380     }
 381
 382     if (*copy_range) {
 383         ret = bdrv_co_copy_range(s->source, offset, s->target, offset, nbytes,
 384                                  0, s->write_flags);
 385         if (ret < 0) {
 386             trace_block_copy_copy_range_fail(s, offset, ret);
 387             *copy_range = false;
 388             /* Fallback to read+write with allocated buffer */
 389         } else {
 390             return 0;
 391         }
 392     }
 393
 394     /*
 395      * In case of failed copy_range request above, we may proceed with buffered
 396      * request larger than BLOCK_COPY_MAX_BUFFER. Still, further requests will
 397      * be properly limited, so don't care too much. Moreover the most likely
 398      * case (copy_range is unsupported for the configuration, so the very first
 399      * copy_range request fails) is handled by setting large copy_size only
 400      * after first successful copy_range.
 401      */
 402
 403     bounce_buffer = qemu_blockalign(s->source->bs, nbytes);
 404
 405     ret = bdrv_co_pread(s->source, offset, nbytes, bounce_buffer, 0);
 406     if (ret < 0) {
 407         trace_block_copy_read_fail(s, offset, ret);
 408         *error_is_read = true;
 409         goto out;
 410     }
 411
 412     ret = bdrv_co_pwrite(s->target, offset, nbytes, bounce_buffer,
 413                          s->write_flags);
 414     if (ret < 0) {
 415         trace_block_copy_write_fail(s, offset, ret);
 416         *error_is_read = false;
 417         goto out;
 418     }
 419
 420 out:
 421     qemu_vfree(bounce_buffer);
 422
 423     return ret;
 424 }
 425
 426 static void block_copy_handle_copy_range_result(BlockCopyState *s,
 427                                                 bool is_success)
 428 {
 429     if (!s->use_copy_range) {
 430         /* already disabled */
 431         return;
 432     }
 433
 434     if (is_success) {
 435         /*
 436          * Successful copy-range. Now increase copy_size.  copy_range
 437          * does not respect max_transfer (it's a TODO), so we factor
 438          * that in here.
 439          */
 440         s->copy_size =
 441                 MIN(MAX(s->cluster_size, BLOCK_COPY_MAX_COPY_RANGE),
 442                     QEMU_ALIGN_DOWN(block_copy_max_transfer(s->source,
 443                                                             s->target),
 444                                     s->cluster_size));
 445     } else {
 446         /* Copy-range failed, disable it. */
 447         s->use_copy_range = false;
 448         s->copy_size = MAX(s->cluster_size, BLOCK_COPY_MAX_BUFFER);
 449     }
 450 }
 451
 452 static coroutine_fn int block_copy_task_entry(AioTask *task)
 453 {
 454     BlockCopyTask *t = container_of(task, BlockCopyTask, task);
 455     bool error_is_read = false;
 456     bool copy_range = t->copy_range;
 457     int ret;
 458
 459     ret = block_copy_do_copy(t->s, t->offset, t->bytes, t->zeroes,
 460                              &copy_range, &error_is_read);
 461     if (t->copy_range) {
 462         block_copy_handle_copy_range_result(t->s, copy_range);
 463     }
 464     if (ret < 0) {
 465         if (!t->call_state->ret) {
 466             t->call_state->ret = ret;
 467             t->call_state->error_is_read = error_is_read;
 468         }
 469     } else {
 470         progress_work_done(t->s->progress, t->bytes);
 471     }
 472     co_put_to_shres(t->s->mem, t->bytes);
 473     block_copy_task_end(t, ret);
 474
 475     return ret;
 476 }
 477
 478 static int block_copy_block_status(BlockCopyState *s, int64_t offset,
 479                                    int64_t bytes, int64_t *pnum)
 480 {
 481     int64_t num;
 482     BlockDriverState *base;
 483     int ret;
 484
 485     if (s->skip_unallocated) {
 486         base = bdrv_backing_chain_next(s->source->bs);
 487     } else {
 488         base = NULL;
 489     }
 490
 491     ret = bdrv_block_status_above(s->source->bs, base, offset, bytes, &num,
 492                                   NULL, NULL);
 493     if (ret < 0 || num < s->cluster_size) {
 494         /*
 495          * On error or if failed to obtain large enough chunk just fallback to
 496          * copy one cluster.
 497          */
 498         num = s->cluster_size;
 499         ret = BDRV_BLOCK_ALLOCATED | BDRV_BLOCK_DATA;
 500     } else if (offset + num == s->len) {
 501         num = QEMU_ALIGN_UP(num, s->cluster_size);
 502     } else {
 503         num = QEMU_ALIGN_DOWN(num, s->cluster_size);
 504     }
 505
 506     *pnum = num;
 507     return ret;
 508 }
 509
 510 /*
 511  * Check if the cluster starting at offset is allocated or not.
 512  * return via pnum the number of contiguous clusters sharing this allocation.
 513  */
 514 static int block_copy_is_cluster_allocated(BlockCopyState *s, int64_t offset,
 515                                            int64_t *pnum)
 516 {
 517     BlockDriverState *bs = s->source->bs;
 518     int64_t count, total_count = 0;
 519     int64_t bytes = s->len - offset;
 520     int ret;
 521
 522     assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
 523
 524     while (true) {
 525         ret = bdrv_is_allocated(bs, offset, bytes, &count);
 526         if (ret < 0) {
 527             return ret;
 528         }
 529
 530         total_count += count;
 531
 532         if (ret || count == 0) {
 533             /*
 534              * ret: partial segment(s) are considered allocated.
 535              * otherwise: unallocated tail is treated as an entire segment.
 536              */
 537             *pnum = DIV_ROUND_UP(total_count, s->cluster_size);
 538             return ret;
 539         }
 540
 541         /* Unallocated segment(s) with uncertain following segment(s) */
 542         if (total_count >= s->cluster_size) {
 543             *pnum = total_count / s->cluster_size;
 544             return 0;
 545         }
 546
 547         offset += count;
 548         bytes -= count;
 549     }
 550 }
 551
 552 /*
 553  * Reset bits in copy_bitmap starting at offset if they represent unallocated
 554  * data in the image. May reset subsequent contiguous bits.
 555  * @return 0 when the cluster at @offset was unallocated,
 556  *         1 otherwise, and -ret on error.
 557  */
 558 int64_t block_copy_reset_unallocated(BlockCopyState *s,
 559                                      int64_t offset, int64_t *count)
 560 {
 561     int ret;
 562     int64_t clusters, bytes;
 563
 564     ret = block_copy_is_cluster_allocated(s, offset, &clusters);
 565     if (ret < 0) {
 566         return ret;
 567     }
 568
 569     bytes = clusters * s->cluster_size;
 570
 571     if (!ret) {
 572         bdrv_reset_dirty_bitmap(s->copy_bitmap, offset, bytes);
 573         progress_set_remaining(s->progress,
 574                                bdrv_get_dirty_count(s->copy_bitmap) +
 575                                s->in_flight_bytes);
 576     }
 577
 578     *count = bytes;
 579     return ret;
 580 }
 581
 582 /*
 583  * block_copy_dirty_clusters
 584  *
 585  * Copy dirty clusters in @offset/@bytes range.
 586  * Returns 1 if dirty clusters found and successfully copied, 0 if no dirty
 587  * clusters found and -errno on failure.
 588  */
 589 static int coroutine_fn
 590 block_copy_dirty_clusters(BlockCopyCallState *call_state)
 591 {
 592     BlockCopyState *s = call_state->s;
 593     int64_t offset = call_state->offset;
 594     int64_t bytes = call_state->bytes;
 595
 596     int ret = 0;
 597     bool found_dirty = false;
 598     int64_t end = offset + bytes;
 599     AioTaskPool *aio = NULL;
 600
 601     /*
 602      * block_copy() user is responsible for keeping source and target in same
 603      * aio context
 604      */
 605     assert(bdrv_get_aio_context(s->source->bs) ==
 606            bdrv_get_aio_context(s->target->bs));
 607
 608     assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
 609     assert(QEMU_IS_ALIGNED(bytes, s->cluster_size));
 610
 611     while (bytes && aio_task_pool_status(aio) == 0 && !call_state->cancelled) {
 612         BlockCopyTask *task;
 613         int64_t status_bytes;
 614
 615         task = block_copy_task_create(s, call_state, offset, bytes);
 616         if (!task) {
 617             /* No more dirty bits in the bitmap */
 618             trace_block_copy_skip_range(s, offset, bytes);
 619             break;
 620         }
 621         if (task->offset > offset) {
 622             trace_block_copy_skip_range(s, offset, task->offset - offset);
 623         }
 624
 625         found_dirty = true;
 626
 627         ret = block_copy_block_status(s, task->offset, task->bytes,
 628                                       &status_bytes);
 629         assert(ret >= 0); /* never fail */
 630         if (status_bytes < task->bytes) {
 631             block_copy_task_shrink(task, status_bytes);
 632         }
 633         if (s->skip_unallocated && !(ret & BDRV_BLOCK_ALLOCATED)) {
 634             block_copy_task_end(task, 0);
 635             progress_set_remaining(s->progress,
 636                                    bdrv_get_dirty_count(s->copy_bitmap) +
 637                                    s->in_flight_bytes);
 638             trace_block_copy_skip_range(s, task->offset, task->bytes);
 639             offset = task_end(task);
 640             bytes = end - offset;
 641             g_free(task);
 642             continue;
 643         }
 644         if (ret & BDRV_BLOCK_ZERO) {
 645             task->zeroes = true;
 646             task->copy_range = false;
 647         }
 648
 649         if (!call_state->ignore_ratelimit) {
 650             uint64_t ns = ratelimit_calculate_delay(&s->rate_limit, 0);
 651             if (ns > 0) {
 652                 block_copy_task_end(task, -EAGAIN);
 653                 g_free(task);
 654                 qemu_co_sleep_ns_wakeable(&call_state->sleep,
 655                                           QEMU_CLOCK_REALTIME, ns);
 656                 continue;
 657             }
 658         }
 659
 660         ratelimit_calculate_delay(&s->rate_limit, task->bytes);
 661
 662         trace_block_copy_process(s, task->offset);
 663
 664         co_get_from_shres(s->mem, task->bytes);
 665
 666         offset = task_end(task);
 667         bytes = end - offset;
 668
 669         if (!aio && bytes) {
 670             aio = aio_task_pool_new(call_state->max_workers);
 671         }
 672
 673         ret = block_copy_task_run(aio, task);
 674         if (ret < 0) {
 675             goto out;
 676         }
 677     }
 678
 679 out:
 680     if (aio) {
 681         aio_task_pool_wait_all(aio);
 682
 683         /*
 684          * We are not really interested in -ECANCELED returned from
 685          * block_copy_task_run. If it fails, it means some task already failed
 686          * for real reason, let's return first failure.
 687          * Still, assert that we don't rewrite failure by success.
 688          *
 689          * Note: ret may be positive here because of block-status result.
 690          */
 691         assert(ret >= 0 || aio_task_pool_status(aio) < 0);
 692         ret = aio_task_pool_status(aio);
 693
 694         aio_task_pool_free(aio);
 695     }
 696
 697     return ret < 0 ? ret : found_dirty;
 698 }
 699
 700 void block_copy_kick(BlockCopyCallState *call_state)
 701 {
 702     qemu_co_sleep_wake(&call_state->sleep);
 703 }
 704
 705 /*
 706  * block_copy_common
 707  *
 708  * Copy requested region, accordingly to dirty bitmap.
 709  * Collaborate with parallel block_copy requests: if they succeed it will help
 710  * us. If they fail, we will retry not-copied regions. So, if we return error,
 711  * it means that some I/O operation failed in context of _this_ block_copy call,
 712  * not some parallel operation.
 713  */
 714 static int coroutine_fn block_copy_common(BlockCopyCallState *call_state)
 715 {
 716     int ret;
 717
 718     QLIST_INSERT_HEAD(&call_state->s->calls, call_state, list);
 719
 720     do {
 721         ret = block_copy_dirty_clusters(call_state);
 722
 723         if (ret == 0 && !call_state->cancelled) {
 724             ret = block_copy_wait_one(call_state->s, call_state->offset,
 725                                       call_state->bytes);
 726         }
 727
 728         /*
 729          * We retry in two cases:
 730          * 1. Some progress done
 731          *    Something was copied, which means that there were yield points
 732          *    and some new dirty bits may have appeared (due to failed parallel
 733          *    block-copy requests).
 734          * 2. We have waited for some intersecting block-copy request
 735          *    It may have failed and produced new dirty bits.
 736          */
 737     } while (ret > 0 && !call_state->cancelled);
 738
 739     call_state->finished = true;
 740
 741     if (call_state->cb) {
 742         call_state->cb(call_state->cb_opaque);
 743     }
 744
 745     QLIST_REMOVE(call_state, list);
 746
 747     return ret;
 748 }
 749
 750 int coroutine_fn block_copy(BlockCopyState *s, int64_t start, int64_t bytes,
 751                             bool ignore_ratelimit)
 752 {
 753     BlockCopyCallState call_state = {
 754         .s = s,
 755         .offset = start,
 756         .bytes = bytes,
 757         .ignore_ratelimit = ignore_ratelimit,
 758         .max_workers = BLOCK_COPY_MAX_WORKERS,
 759     };
 760
 761     return block_copy_common(&call_state);
 762 }
 763
 764 static void coroutine_fn block_copy_async_co_entry(void *opaque)
 765 {
 766     block_copy_common(opaque);
 767 }
 768
 769 BlockCopyCallState *block_copy_async(BlockCopyState *s,
 770                                      int64_t offset, int64_t bytes,
 771                                      int max_workers, int64_t max_chunk,
 772                                      BlockCopyAsyncCallbackFunc cb,
 773                                      void *cb_opaque)
 774 {
 775     BlockCopyCallState *call_state = g_new(BlockCopyCallState, 1);
 776
 777     *call_state = (BlockCopyCallState) {
 778         .s = s,
 779         .offset = offset,
 780         .bytes = bytes,
 781         .max_workers = max_workers,
 782         .max_chunk = max_chunk,
 783         .cb = cb,
 784         .cb_opaque = cb_opaque,
 785
 786         .co = qemu_coroutine_create(block_copy_async_co_entry, call_state),
 787     };
 788
 789     qemu_coroutine_enter(call_state->co);
 790
 791     return call_state;
 792 }
 793
 794 void block_copy_call_free(BlockCopyCallState *call_state)
 795 {
 796     if (!call_state) {
 797         return;
 798     }
 799
 800     assert(call_state->finished);
 801     g_free(call_state);
 802 }
 803
 804 bool block_copy_call_finished(BlockCopyCallState *call_state)
 805 {
 806     return call_state->finished;
 807 }
 808
 809 bool block_copy_call_succeeded(BlockCopyCallState *call_state)
 810 {
 811     return call_state->finished && !call_state->cancelled &&
 812         call_state->ret == 0;
 813 }
 814
 815 bool block_copy_call_failed(BlockCopyCallState *call_state)
 816 {
 817     return call_state->finished && !call_state->cancelled &&
 818         call_state->ret < 0;
 819 }
 820
 821 bool block_copy_call_cancelled(BlockCopyCallState *call_state)
 822 {
 823     return call_state->cancelled;
 824 }
 825
 826 int block_copy_call_status(BlockCopyCallState *call_state, bool *error_is_read)
 827 {
 828     assert(call_state->finished);
 829     if (error_is_read) {
 830         *error_is_read = call_state->error_is_read;
 831     }
 832     return call_state->ret;
 833 }
 834
 835 void block_copy_call_cancel(BlockCopyCallState *call_state)
 836 {
 837     call_state->cancelled = true;
 838     block_copy_kick(call_state);
 839 }
 840
 841 BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s)
 842 {
 843     return s->copy_bitmap;
 844 }
 845
 846 void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip)
 847 {
 848     s->skip_unallocated = skip;
 849 }
 850
 851 void block_copy_set_speed(BlockCopyState *s, uint64_t speed)
 852 {
 853     ratelimit_set_speed(&s->rate_limit, speed, BLOCK_COPY_SLICE_TIME);
 854
 855     /*
 856      * Note: it's good to kick all call states from here, but it should be done
 857      * only from a coroutine, to not crash if s->calls list changed while
 858      * entering one call. So for now, the only user of this function kicks its
 859      * only one call_state by hand.
 860      */
 861 }