block/backup.c

   1 /*
   2  * QEMU backup
   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  *
  10  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  11  * See the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #include "qemu/osdep.h"
  16
  17 #include "trace.h"
  18 #include "block/block.h"
  19 #include "block/block_int.h"
  20 #include "block/blockjob_int.h"
  21 #include "block/block_backup.h"
  22 #include "block/block-copy.h"
  23 #include "block/dirty-bitmap.h"
  24 #include "qapi/error.h"
  25 #include "qemu/cutils.h"
  26 #include "sysemu/block-backend.h"
  27 #include "qemu/bitmap.h"
  28 #include "qemu/error-report.h"
  29
  30 #include "block/copy-before-write.h"
  31
  32 typedef struct BackupBlockJob {
  33     BlockJob common;
  34     BlockDriverState *cbw;
  35     BlockDriverState *source_bs;
  36     BlockDriverState *target_bs;
  37
  38     BdrvDirtyBitmap *sync_bitmap;
  39
  40     MirrorSyncMode sync_mode;
  41     BitmapSyncMode bitmap_mode;
  42     BlockdevOnError on_source_error;
  43     BlockdevOnError on_target_error;
  44     uint64_t len;
  45     int64_t cluster_size;
  46     BackupPerf perf;
  47
  48     BlockCopyState *bcs;
  49
  50     bool wait;
  51     BlockCopyCallState *bg_bcs_call;
  52 } BackupBlockJob;
  53
  54 static const BlockJobDriver backup_job_driver;
  55
  56 static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
  57 {
  58     BdrvDirtyBitmap *bm;
  59     bool sync = (((ret == 0) || (job->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS)) \
  60                  && (job->bitmap_mode != BITMAP_SYNC_MODE_NEVER));
  61
  62     if (sync) {
  63         /*
  64          * We succeeded, or we always intended to sync the bitmap.
  65          * Delete this bitmap and install the child.
  66          */
  67         bm = bdrv_dirty_bitmap_abdicate(job->sync_bitmap, NULL);
  68     } else {
  69         /*
  70          * We failed, or we never intended to sync the bitmap anyway.
  71          * Merge the successor back into the parent, keeping all data.
  72          */
  73         bm = bdrv_reclaim_dirty_bitmap(job->sync_bitmap, NULL);
  74     }
  75
  76     assert(bm);
  77
  78     if (ret < 0 && job->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS) {
  79         /* If we failed and synced, merge in the bits we didn't copy: */
  80         bdrv_dirty_bitmap_merge_internal(bm, block_copy_dirty_bitmap(job->bcs),
  81                                          NULL, true);
  82     }
  83 }
  84
  85 static void backup_commit(Job *job)
  86 {
  87     BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
  88     if (s->sync_bitmap) {
  89         backup_cleanup_sync_bitmap(s, 0);
  90     }
  91 }
  92
  93 static void backup_abort(Job *job)
  94 {
  95     BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
  96     if (s->sync_bitmap) {
  97         backup_cleanup_sync_bitmap(s, -1);
  98     }
  99 }
 100
 101 static void backup_clean(Job *job)
 102 {
 103     BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
 104     block_job_remove_all_bdrv(&s->common);
 105     bdrv_cbw_drop(s->cbw);
 106 }
 107
 108 void backup_do_checkpoint(BlockJob *job, Error **errp)
 109 {
 110     BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
 111
 112     assert(block_job_driver(job) == &backup_job_driver);
 113
 114     if (backup_job->sync_mode != MIRROR_SYNC_MODE_NONE) {
 115         error_setg(errp, "The backup job only supports block checkpoint in"
 116                    " sync=none mode");
 117         return;
 118     }
 119
 120     bdrv_set_dirty_bitmap(block_copy_dirty_bitmap(backup_job->bcs), 0,
 121                           backup_job->len);
 122 }
 123
 124 static BlockErrorAction backup_error_action(BackupBlockJob *job,
 125                                             bool read, int error)
 126 {
 127     if (read) {
 128         return block_job_error_action(&job->common, job->on_source_error,
 129                                       true, error);
 130     } else {
 131         return block_job_error_action(&job->common, job->on_target_error,
 132                                       false, error);
 133     }
 134 }
 135
 136 static void coroutine_fn backup_block_copy_callback(void *opaque)
 137 {
 138     BackupBlockJob *s = opaque;
 139
 140     if (s->wait) {
 141         s->wait = false;
 142         aio_co_wake(s->common.job.co);
 143     } else {
 144         job_enter(&s->common.job);
 145     }
 146 }
 147
 148 static int coroutine_fn backup_loop(BackupBlockJob *job)
 149 {
 150     BlockCopyCallState *s = NULL;
 151     int ret = 0;
 152     bool error_is_read;
 153     BlockErrorAction act;
 154
 155     while (true) { /* retry loop */
 156         job->bg_bcs_call = s = block_copy_async(job->bcs, 0,
 157                 QEMU_ALIGN_UP(job->len, job->cluster_size),
 158                 job->perf.max_workers, job->perf.max_chunk,
 159                 backup_block_copy_callback, job);
 160
 161         while (!block_copy_call_finished(s) &&
 162                !job_is_cancelled(&job->common.job))
 163         {
 164             job_yield(&job->common.job);
 165         }
 166
 167         if (!block_copy_call_finished(s)) {
 168             assert(job_is_cancelled(&job->common.job));
 169             /*
 170              * Note that we can't use job_yield() here, as it doesn't work for
 171              * cancelled job.
 172              */
 173             block_copy_call_cancel(s);
 174             job->wait = true;
 175             qemu_coroutine_yield();
 176             assert(block_copy_call_finished(s));
 177             ret = 0;
 178             goto out;
 179         }
 180
 181         if (job_is_cancelled(&job->common.job) ||
 182             block_copy_call_succeeded(s))
 183         {
 184             ret = 0;
 185             goto out;
 186         }
 187
 188         if (block_copy_call_cancelled(s)) {
 189             /*
 190              * Job is not cancelled but only block-copy call. This is possible
 191              * after job pause. Now the pause is finished, start new block-copy
 192              * iteration.
 193              */
 194             block_copy_call_free(s);
 195             continue;
 196         }
 197
 198         /* The only remaining case is failed block-copy call. */
 199         assert(block_copy_call_failed(s));
 200
 201         ret = block_copy_call_status(s, &error_is_read);
 202         act = backup_error_action(job, error_is_read, -ret);
 203         switch (act) {
 204         case BLOCK_ERROR_ACTION_REPORT:
 205             goto out;
 206         case BLOCK_ERROR_ACTION_STOP:
 207             /*
 208              * Go to pause prior to starting new block-copy call on the next
 209              * iteration.
 210              */
 211             job_pause_point(&job->common.job);
 212             break;
 213         case BLOCK_ERROR_ACTION_IGNORE:
 214             /* Proceed to new block-copy call to retry. */
 215             break;
 216         default:
 217             abort();
 218         }
 219
 220         block_copy_call_free(s);
 221     }
 222
 223 out:
 224     block_copy_call_free(s);
 225     job->bg_bcs_call = NULL;
 226     return ret;
 227 }
 228
 229 static void backup_init_bcs_bitmap(BackupBlockJob *job)
 230 {
 231     uint64_t estimate;
 232     BdrvDirtyBitmap *bcs_bitmap = block_copy_dirty_bitmap(job->bcs);
 233
 234     if (job->sync_mode == MIRROR_SYNC_MODE_BITMAP) {
 235         bdrv_clear_dirty_bitmap(bcs_bitmap, NULL);
 236         bdrv_dirty_bitmap_merge_internal(bcs_bitmap, job->sync_bitmap, NULL,
 237                                          true);
 238     } else if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
 239         /*
 240          * We can't hog the coroutine to initialize this thoroughly.
 241          * Set a flag and resume work when we are able to yield safely.
 242          */
 243         block_copy_set_skip_unallocated(job->bcs, true);
 244     }
 245
 246     estimate = bdrv_get_dirty_count(bcs_bitmap);
 247     job_progress_set_remaining(&job->common.job, estimate);
 248 }
 249
 250 static int coroutine_fn backup_run(Job *job, Error **errp)
 251 {
 252     BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
 253     int ret;
 254
 255     backup_init_bcs_bitmap(s);
 256
 257     if (s->sync_mode == MIRROR_SYNC_MODE_TOP) {
 258         int64_t offset = 0;
 259         int64_t count;
 260
 261         for (offset = 0; offset < s->len; ) {
 262             if (job_is_cancelled(job)) {
 263                 return -ECANCELED;
 264             }
 265
 266             job_pause_point(job);
 267
 268             if (job_is_cancelled(job)) {
 269                 return -ECANCELED;
 270             }
 271
 272             /* rdlock protects the subsequent call to bdrv_is_allocated() */
 273             bdrv_graph_co_rdlock();
 274             ret = block_copy_reset_unallocated(s->bcs, offset, &count);
 275             bdrv_graph_co_rdunlock();
 276             if (ret < 0) {
 277                 return ret;
 278             }
 279
 280             offset += count;
 281         }
 282         block_copy_set_skip_unallocated(s->bcs, false);
 283     }
 284
 285     if (s->sync_mode == MIRROR_SYNC_MODE_NONE) {
 286         /*
 287          * All bits are set in bcs bitmap to allow any cluster to be copied.
 288          * This does not actually require them to be copied.
 289          */
 290         while (!job_is_cancelled(job)) {
 291             /*
 292              * Yield until the job is cancelled.  We just let our before_write
 293              * notify callback service CoW requests.
 294              */
 295             job_yield(job);
 296         }
 297     } else {
 298         return backup_loop(s);
 299     }
 300
 301     return 0;
 302 }
 303
 304 static void coroutine_fn backup_pause(Job *job)
 305 {
 306     BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
 307
 308     if (s->bg_bcs_call && !block_copy_call_finished(s->bg_bcs_call)) {
 309         block_copy_call_cancel(s->bg_bcs_call);
 310         s->wait = true;
 311         qemu_coroutine_yield();
 312     }
 313 }
 314
 315 static void backup_set_speed(BlockJob *job, int64_t speed)
 316 {
 317     BackupBlockJob *s = container_of(job, BackupBlockJob, common);
 318
 319     /*
 320      * block_job_set_speed() is called first from block_job_create(), when we
 321      * don't yet have s->bcs.
 322      */
 323     if (s->bcs) {
 324         block_copy_set_speed(s->bcs, speed);
 325         if (s->bg_bcs_call) {
 326             block_copy_kick(s->bg_bcs_call);
 327         }
 328     }
 329 }
 330
 331 static bool backup_cancel(Job *job, bool force)
 332 {
 333     BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
 334
 335     bdrv_cancel_in_flight(s->target_bs);
 336     return true;
 337 }
 338
 339 static const BlockJobDriver backup_job_driver = {
 340     .job_driver = {
 341         .instance_size          = sizeof(BackupBlockJob),
 342         .job_type               = JOB_TYPE_BACKUP,
 343         .free                   = block_job_free,
 344         .user_resume            = block_job_user_resume,
 345         .run                    = backup_run,
 346         .commit                 = backup_commit,
 347         .abort                  = backup_abort,
 348         .clean                  = backup_clean,
 349         .pause                  = backup_pause,
 350         .cancel                 = backup_cancel,
 351     },
 352     .set_speed = backup_set_speed,
 353 };
 354
 355 BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
 356                   BlockDriverState *target, int64_t speed,
 357                   MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
 358                   BitmapSyncMode bitmap_mode,
 359                   bool compress, bool discard_source,
 360                   const char *filter_node_name,
 361                   BackupPerf *perf,
 362                   BlockdevOnError on_source_error,
 363                   BlockdevOnError on_target_error,
 364                   int creation_flags,
 365                   BlockCompletionFunc *cb, void *opaque,
 366                   JobTxn *txn, Error **errp)
 367 {
 368     int64_t len, target_len;
 369     BackupBlockJob *job = NULL;
 370     int64_t cluster_size;
 371     BlockDriverState *cbw = NULL;
 372     BlockCopyState *bcs = NULL;
 373
 374     assert(bs);
 375     assert(target);
 376     GLOBAL_STATE_CODE();
 377
 378     /* QMP interface protects us from these cases */
 379     assert(sync_mode != MIRROR_SYNC_MODE_INCREMENTAL);
 380     assert(sync_bitmap || sync_mode != MIRROR_SYNC_MODE_BITMAP);
 381
 382     if (bs == target) {
 383         error_setg(errp, "Source and target cannot be the same");
 384         return NULL;
 385     }
 386
 387     bdrv_graph_rdlock_main_loop();
 388     if (!bdrv_is_inserted(bs)) {
 389         error_setg(errp, "Device is not inserted: %s",
 390                    bdrv_get_device_name(bs));
 391         goto error_rdlock;
 392     }
 393
 394     if (!bdrv_is_inserted(target)) {
 395         error_setg(errp, "Device is not inserted: %s",
 396                    bdrv_get_device_name(target));
 397         goto error_rdlock;
 398     }
 399
 400     if (compress && !bdrv_supports_compressed_writes(target)) {
 401         error_setg(errp, "Compression is not supported for this drive %s",
 402                    bdrv_get_device_name(target));
 403         goto error_rdlock;
 404     }
 405
 406     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
 407         goto error_rdlock;
 408     }
 409
 410     if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
 411         goto error_rdlock;
 412     }
 413     bdrv_graph_rdunlock_main_loop();
 414
 415     if (perf->max_workers < 1 || perf->max_workers > INT_MAX) {
 416         error_setg(errp, "max-workers must be between 1 and %d", INT_MAX);
 417         return NULL;
 418     }
 419
 420     if (perf->max_chunk < 0) {
 421         error_setg(errp, "max-chunk must be zero (which means no limit) or "
 422                    "positive");
 423         return NULL;
 424     }
 425
 426     if (sync_bitmap) {
 427         /* If we need to write to this bitmap, check that we can: */
 428         if (bitmap_mode != BITMAP_SYNC_MODE_NEVER &&
 429             bdrv_dirty_bitmap_check(sync_bitmap, BDRV_BITMAP_DEFAULT, errp)) {
 430             return NULL;
 431         }
 432
 433         /* Create a new bitmap, and freeze/disable this one. */
 434         if (bdrv_dirty_bitmap_create_successor(sync_bitmap, errp) < 0) {
 435             return NULL;
 436         }
 437     }
 438
 439     len = bdrv_getlength(bs);
 440     if (len < 0) {
 441         GRAPH_RDLOCK_GUARD_MAINLOOP();
 442         error_setg_errno(errp, -len, "Unable to get length for '%s'",
 443                          bdrv_get_device_or_node_name(bs));
 444         goto error;
 445     }
 446
 447     target_len = bdrv_getlength(target);
 448     if (target_len < 0) {
 449         GRAPH_RDLOCK_GUARD_MAINLOOP();
 450         error_setg_errno(errp, -target_len, "Unable to get length for '%s'",
 451                          bdrv_get_device_or_node_name(bs));
 452         goto error;
 453     }
 454
 455     if (target_len != len) {
 456         error_setg(errp, "Source and target image have different sizes");
 457         goto error;
 458     }
 459
 460     cbw = bdrv_cbw_append(bs, target, filter_node_name, discard_source,
 461                           &bcs, errp);
 462     if (!cbw) {
 463         goto error;
 464     }
 465
 466     cluster_size = block_copy_cluster_size(bcs);
 467
 468     if (perf->max_chunk && perf->max_chunk < cluster_size) {
 469         error_setg(errp, "Required max-chunk (%" PRIi64 ") is less than backup "
 470                    "cluster size (%" PRIi64 ")", perf->max_chunk, cluster_size);
 471         goto error;
 472     }
 473
 474     /* job->len is fixed, so we can't allow resize */
 475     job = block_job_create(job_id, &backup_job_driver, txn, cbw,
 476                            0, BLK_PERM_ALL,
 477                            speed, creation_flags, cb, opaque, errp);
 478     if (!job) {
 479         goto error;
 480     }
 481
 482     job->cbw = cbw;
 483     job->source_bs = bs;
 484     job->target_bs = target;
 485     job->on_source_error = on_source_error;
 486     job->on_target_error = on_target_error;
 487     job->sync_mode = sync_mode;
 488     job->sync_bitmap = sync_bitmap;
 489     job->bitmap_mode = bitmap_mode;
 490     job->bcs = bcs;
 491     job->cluster_size = cluster_size;
 492     job->len = len;
 493     job->perf = *perf;
 494
 495     block_copy_set_copy_opts(bcs, perf->use_copy_range, compress);
 496     block_copy_set_progress_meter(bcs, &job->common.job.progress);
 497     block_copy_set_speed(bcs, speed);
 498
 499     /* Required permissions are taken by copy-before-write filter target */
 500     bdrv_graph_wrlock();
 501     block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
 502                        &error_abort);
 503     bdrv_graph_wrunlock();
 504
 505     return &job->common;
 506
 507  error:
 508     if (sync_bitmap) {
 509         bdrv_reclaim_dirty_bitmap(sync_bitmap, NULL);
 510     }
 511     if (cbw) {
 512         bdrv_cbw_drop(cbw);
 513     }
 514
 515     return NULL;
 516
 517 error_rdlock:
 518     bdrv_graph_rdunlock_main_loop();
 519     return NULL;
 520 }