block/block-backend.c

   1 /*
   2  * QEMU Block backends
   3  *
   4  * Copyright (C) 2014-2016 Red Hat, Inc.
   5  *
   6  * Authors:
   7  *  Markus Armbruster <armbru@redhat.com>,
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2.1
  10  * or later.  See the COPYING.LIB file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "sysemu/block-backend.h"
  15 #include "block/block_int.h"
  16 #include "block/blockjob.h"
  17 #include "block/coroutines.h"
  18 #include "block/throttle-groups.h"
  19 #include "hw/qdev-core.h"
  20 #include "sysemu/blockdev.h"
  21 #include "sysemu/runstate.h"
  22 #include "sysemu/replay.h"
  23 #include "qapi/error.h"
  24 #include "qapi/qapi-events-block.h"
  25 #include "qemu/id.h"
  26 #include "qemu/main-loop.h"
  27 #include "qemu/option.h"
  28 #include "trace.h"
  29 #include "migration/misc.h"
  30
  31 /* Number of coroutines to reserve per attached device model */
  32 #define COROUTINE_POOL_RESERVATION 64
  33
  34 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
  35
  36 static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb);
  37
  38 typedef struct BlockBackendAioNotifier {
  39     void (*attached_aio_context)(AioContext *new_context, void *opaque);
  40     void (*detach_aio_context)(void *opaque);
  41     void *opaque;
  42     QLIST_ENTRY(BlockBackendAioNotifier) list;
  43 } BlockBackendAioNotifier;
  44
  45 struct BlockBackend {
  46     char *name;
  47     int refcnt;
  48     BdrvChild *root;
  49     AioContext *ctx;
  50     DriveInfo *legacy_dinfo;    /* null unless created by drive_new() */
  51     QTAILQ_ENTRY(BlockBackend) link;         /* for block_backends */
  52     QTAILQ_ENTRY(BlockBackend) monitor_link; /* for monitor_block_backends */
  53     BlockBackendPublic public;
  54
  55     DeviceState *dev;           /* attached device model, if any */
  56     const BlockDevOps *dev_ops;
  57     void *dev_opaque;
  58
  59     /* If the BDS tree is removed, some of its options are stored here (which
  60      * can be used to restore those options in the new BDS on insert) */
  61     BlockBackendRootState root_state;
  62
  63     bool enable_write_cache;
  64
  65     /* I/O stats (display with "info blockstats"). */
  66     BlockAcctStats stats;
  67
  68     BlockdevOnError on_read_error, on_write_error;
  69     bool iostatus_enabled;
  70     BlockDeviceIoStatus iostatus;
  71
  72     uint64_t perm;
  73     uint64_t shared_perm;
  74     bool disable_perm;
  75
  76     bool allow_aio_context_change;
  77     bool allow_write_beyond_eof;
  78
  79     /* Protected by BQL */
  80     NotifierList remove_bs_notifiers, insert_bs_notifiers;
  81     QLIST_HEAD(, BlockBackendAioNotifier) aio_notifiers;
  82
  83     int quiesce_counter;
  84     CoQueue queued_requests;
  85     bool disable_request_queuing;
  86
  87     VMChangeStateEntry *vmsh;
  88     bool force_allow_inactivate;
  89
  90     /* Number of in-flight aio requests.  BlockDriverState also counts
  91      * in-flight requests but aio requests can exist even when blk->root is
  92      * NULL, so we cannot rely on its counter for that case.
  93      * Accessed with atomic ops.
  94      */
  95     unsigned int in_flight;
  96 };
  97
  98 typedef struct BlockBackendAIOCB {
  99     BlockAIOCB common;
 100     BlockBackend *blk;
 101     int ret;
 102 } BlockBackendAIOCB;
 103
 104 static const AIOCBInfo block_backend_aiocb_info = {
 105     .get_aio_context = blk_aiocb_get_aio_context,
 106     .aiocb_size = sizeof(BlockBackendAIOCB),
 107 };
 108
 109 static void drive_info_del(DriveInfo *dinfo);
 110 static BlockBackend *bdrv_first_blk(BlockDriverState *bs);
 111
 112 /* All BlockBackends. Protected by BQL. */
 113 static QTAILQ_HEAD(, BlockBackend) block_backends =
 114     QTAILQ_HEAD_INITIALIZER(block_backends);
 115
 116 /*
 117  * All BlockBackends referenced by the monitor and which are iterated through by
 118  * blk_next(). Protected by BQL.
 119  */
 120 static QTAILQ_HEAD(, BlockBackend) monitor_block_backends =
 121     QTAILQ_HEAD_INITIALIZER(monitor_block_backends);
 122
 123 static void blk_root_inherit_options(BdrvChildRole role, bool parent_is_format,
 124                                      int *child_flags, QDict *child_options,
 125                                      int parent_flags, QDict *parent_options)
 126 {
 127     /* We're not supposed to call this function for root nodes */
 128     abort();
 129 }
 130 static void blk_root_drained_begin(BdrvChild *child);
 131 static bool blk_root_drained_poll(BdrvChild *child);
 132 static void blk_root_drained_end(BdrvChild *child, int *drained_end_counter);
 133
 134 static void blk_root_change_media(BdrvChild *child, bool load);
 135 static void blk_root_resize(BdrvChild *child);
 136
 137 static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
 138                                     GHashTable *visited, Transaction *tran,
 139                                     Error **errp);
 140
 141 static char *blk_root_get_parent_desc(BdrvChild *child)
 142 {
 143     BlockBackend *blk = child->opaque;
 144     g_autofree char *dev_id = NULL;
 145
 146     if (blk->name) {
 147         return g_strdup_printf("block device '%s'", blk->name);
 148     }
 149
 150     dev_id = blk_get_attached_dev_id(blk);
 151     if (*dev_id) {
 152         return g_strdup_printf("block device '%s'", dev_id);
 153     } else {
 154         /* TODO Callback into the BB owner for something more detailed */
 155         return g_strdup("an unnamed block device");
 156     }
 157 }
 158
 159 static const char *blk_root_get_name(BdrvChild *child)
 160 {
 161     return blk_name(child->opaque);
 162 }
 163
 164 static void blk_vm_state_changed(void *opaque, bool running, RunState state)
 165 {
 166     Error *local_err = NULL;
 167     BlockBackend *blk = opaque;
 168
 169     if (state == RUN_STATE_INMIGRATE) {
 170         return;
 171     }
 172
 173     qemu_del_vm_change_state_handler(blk->vmsh);
 174     blk->vmsh = NULL;
 175     blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
 176     if (local_err) {
 177         error_report_err(local_err);
 178     }
 179 }
 180
 181 /*
 182  * Notifies the user of the BlockBackend that migration has completed. qdev
 183  * devices can tighten their permissions in response (specifically revoke
 184  * shared write permissions that we needed for storage migration).
 185  *
 186  * If an error is returned, the VM cannot be allowed to be resumed.
 187  */
 188 static void blk_root_activate(BdrvChild *child, Error **errp)
 189 {
 190     BlockBackend *blk = child->opaque;
 191     Error *local_err = NULL;
 192     uint64_t saved_shared_perm;
 193
 194     if (!blk->disable_perm) {
 195         return;
 196     }
 197
 198     blk->disable_perm = false;
 199
 200     /*
 201      * blk->shared_perm contains the permissions we want to share once
 202      * migration is really completely done.  For now, we need to share
 203      * all; but we also need to retain blk->shared_perm, which is
 204      * overwritten by a successful blk_set_perm() call.  Save it and
 205      * restore it below.
 206      */
 207     saved_shared_perm = blk->shared_perm;
 208
 209     blk_set_perm(blk, blk->perm, BLK_PERM_ALL, &local_err);
 210     if (local_err) {
 211         error_propagate(errp, local_err);
 212         blk->disable_perm = true;
 213         return;
 214     }
 215     blk->shared_perm = saved_shared_perm;
 216
 217     if (runstate_check(RUN_STATE_INMIGRATE)) {
 218         /* Activation can happen when migration process is still active, for
 219          * example when nbd_server_add is called during non-shared storage
 220          * migration. Defer the shared_perm update to migration completion. */
 221         if (!blk->vmsh) {
 222             blk->vmsh = qemu_add_vm_change_state_handler(blk_vm_state_changed,
 223                                                          blk);
 224         }
 225         return;
 226     }
 227
 228     blk_set_perm(blk, blk->perm, blk->shared_perm, &local_err);
 229     if (local_err) {
 230         error_propagate(errp, local_err);
 231         blk->disable_perm = true;
 232         return;
 233     }
 234 }
 235
 236 void blk_set_force_allow_inactivate(BlockBackend *blk)
 237 {
 238     GLOBAL_STATE_CODE();
 239     blk->force_allow_inactivate = true;
 240 }
 241
 242 static bool blk_can_inactivate(BlockBackend *blk)
 243 {
 244     /* If it is a guest device, inactivate is ok. */
 245     if (blk->dev || blk_name(blk)[0]) {
 246         return true;
 247     }
 248
 249     /* Inactivating means no more writes to the image can be done,
 250      * even if those writes would be changes invisible to the
 251      * guest.  For block job BBs that satisfy this, we can just allow
 252      * it.  This is the case for mirror job source, which is required
 253      * by libvirt non-shared block migration. */
 254     if (!(blk->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED))) {
 255         return true;
 256     }
 257
 258     return blk->force_allow_inactivate;
 259 }
 260
 261 static int blk_root_inactivate(BdrvChild *child)
 262 {
 263     BlockBackend *blk = child->opaque;
 264
 265     if (blk->disable_perm) {
 266         return 0;
 267     }
 268
 269     if (!blk_can_inactivate(blk)) {
 270         return -EPERM;
 271     }
 272
 273     blk->disable_perm = true;
 274     if (blk->root) {
 275         bdrv_child_try_set_perm(blk->root, 0, BLK_PERM_ALL, &error_abort);
 276     }
 277
 278     return 0;
 279 }
 280
 281 static void blk_root_attach(BdrvChild *child)
 282 {
 283     BlockBackend *blk = child->opaque;
 284     BlockBackendAioNotifier *notifier;
 285
 286     trace_blk_root_attach(child, blk, child->bs);
 287
 288     QLIST_FOREACH(notifier, &blk->aio_notifiers, list) {
 289         bdrv_add_aio_context_notifier(child->bs,
 290                 notifier->attached_aio_context,
 291                 notifier->detach_aio_context,
 292                 notifier->opaque);
 293     }
 294 }
 295
 296 static void blk_root_detach(BdrvChild *child)
 297 {
 298     BlockBackend *blk = child->opaque;
 299     BlockBackendAioNotifier *notifier;
 300
 301     trace_blk_root_detach(child, blk, child->bs);
 302
 303     QLIST_FOREACH(notifier, &blk->aio_notifiers, list) {
 304         bdrv_remove_aio_context_notifier(child->bs,
 305                 notifier->attached_aio_context,
 306                 notifier->detach_aio_context,
 307                 notifier->opaque);
 308     }
 309 }
 310
 311 static AioContext *blk_root_get_parent_aio_context(BdrvChild *c)
 312 {
 313     BlockBackend *blk = c->opaque;
 314     IO_CODE();
 315
 316     return blk_get_aio_context(blk);
 317 }
 318
 319 static const BdrvChildClass child_root = {
 320     .inherit_options    = blk_root_inherit_options,
 321
 322     .change_media       = blk_root_change_media,
 323     .resize             = blk_root_resize,
 324     .get_name           = blk_root_get_name,
 325     .get_parent_desc    = blk_root_get_parent_desc,
 326
 327     .drained_begin      = blk_root_drained_begin,
 328     .drained_poll       = blk_root_drained_poll,
 329     .drained_end        = blk_root_drained_end,
 330
 331     .activate           = blk_root_activate,
 332     .inactivate         = blk_root_inactivate,
 333
 334     .attach             = blk_root_attach,
 335     .detach             = blk_root_detach,
 336
 337     .change_aio_ctx     = blk_root_change_aio_ctx,
 338
 339     .get_parent_aio_context = blk_root_get_parent_aio_context,
 340 };
 341
 342 /*
 343  * Create a new BlockBackend with a reference count of one.
 344  *
 345  * @perm is a bitmasks of BLK_PERM_* constants which describes the permissions
 346  * to request for a block driver node that is attached to this BlockBackend.
 347  * @shared_perm is a bitmask which describes which permissions may be granted
 348  * to other users of the attached node.
 349  * Both sets of permissions can be changed later using blk_set_perm().
 350  *
 351  * Return the new BlockBackend on success, null on failure.
 352  */
 353 BlockBackend *blk_new(AioContext *ctx, uint64_t perm, uint64_t shared_perm)
 354 {
 355     BlockBackend *blk;
 356
 357     GLOBAL_STATE_CODE();
 358
 359     blk = g_new0(BlockBackend, 1);
 360     blk->refcnt = 1;
 361     blk->ctx = ctx;
 362     blk->perm = perm;
 363     blk->shared_perm = shared_perm;
 364     blk_set_enable_write_cache(blk, true);
 365
 366     blk->on_read_error = BLOCKDEV_ON_ERROR_REPORT;
 367     blk->on_write_error = BLOCKDEV_ON_ERROR_ENOSPC;
 368
 369     block_acct_init(&blk->stats);
 370
 371     qemu_co_queue_init(&blk->queued_requests);
 372     notifier_list_init(&blk->remove_bs_notifiers);
 373     notifier_list_init(&blk->insert_bs_notifiers);
 374     QLIST_INIT(&blk->aio_notifiers);
 375
 376     QTAILQ_INSERT_TAIL(&block_backends, blk, link);
 377     return blk;
 378 }
 379
 380 /*
 381  * Create a new BlockBackend connected to an existing BlockDriverState.
 382  *
 383  * @perm is a bitmasks of BLK_PERM_* constants which describes the
 384  * permissions to request for @bs that is attached to this
 385  * BlockBackend.  @shared_perm is a bitmask which describes which
 386  * permissions may be granted to other users of the attached node.
 387  * Both sets of permissions can be changed later using blk_set_perm().
 388  *
 389  * Return the new BlockBackend on success, null on failure.
 390  */
 391 BlockBackend *blk_new_with_bs(BlockDriverState *bs, uint64_t perm,
 392                               uint64_t shared_perm, Error **errp)
 393 {
 394     BlockBackend *blk = blk_new(bdrv_get_aio_context(bs), perm, shared_perm);
 395
 396     GLOBAL_STATE_CODE();
 397
 398     if (blk_insert_bs(blk, bs, errp) < 0) {
 399         blk_unref(blk);
 400         return NULL;
 401     }
 402     return blk;
 403 }
 404
 405 /*
 406  * Creates a new BlockBackend, opens a new BlockDriverState, and connects both.
 407  * The new BlockBackend is in the main AioContext.
 408  *
 409  * Just as with bdrv_open(), after having called this function the reference to
 410  * @options belongs to the block layer (even on failure).
 411  *
 412  * TODO: Remove @filename and @flags; it should be possible to specify a whole
 413  * BDS tree just by specifying the @options QDict (or @reference,
 414  * alternatively). At the time of adding this function, this is not possible,
 415  * though, so callers of this function have to be able to specify @filename and
 416  * @flags.
 417  */
 418 BlockBackend *blk_new_open(const char *filename, const char *reference,
 419                            QDict *options, int flags, Error **errp)
 420 {
 421     BlockBackend *blk;
 422     BlockDriverState *bs;
 423     uint64_t perm = 0;
 424     uint64_t shared = BLK_PERM_ALL;
 425
 426     GLOBAL_STATE_CODE();
 427
 428     /*
 429      * blk_new_open() is mainly used in .bdrv_create implementations and the
 430      * tools where sharing isn't a major concern because the BDS stays private
 431      * and the file is generally not supposed to be used by a second process,
 432      * so we just request permission according to the flags.
 433      *
 434      * The exceptions are xen_disk and blockdev_init(); in these cases, the
 435      * caller of blk_new_open() doesn't make use of the permissions, but they
 436      * shouldn't hurt either. We can still share everything here because the
 437      * guest devices will add their own blockers if they can't share.
 438      */
 439     if ((flags & BDRV_O_NO_IO) == 0) {
 440         perm |= BLK_PERM_CONSISTENT_READ;
 441         if (flags & BDRV_O_RDWR) {
 442             perm |= BLK_PERM_WRITE;
 443         }
 444     }
 445     if (flags & BDRV_O_RESIZE) {
 446         perm |= BLK_PERM_RESIZE;
 447     }
 448     if (flags & BDRV_O_NO_SHARE) {
 449         shared = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
 450     }
 451
 452     blk = blk_new(qemu_get_aio_context(), perm, shared);
 453     bs = bdrv_open(filename, reference, options, flags, errp);
 454     if (!bs) {
 455         blk_unref(blk);
 456         return NULL;
 457     }
 458
 459     blk->root = bdrv_root_attach_child(bs, "root", &child_root,
 460                                        BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
 461                                        perm, shared, blk, errp);
 462     if (!blk->root) {
 463         blk_unref(blk);
 464         return NULL;
 465     }
 466
 467     return blk;
 468 }
 469
 470 static void blk_delete(BlockBackend *blk)
 471 {
 472     assert(!blk->refcnt);
 473     assert(!blk->name);
 474     assert(!blk->dev);
 475     if (blk->public.throttle_group_member.throttle_state) {
 476         blk_io_limits_disable(blk);
 477     }
 478     if (blk->root) {
 479         blk_remove_bs(blk);
 480     }
 481     if (blk->vmsh) {
 482         qemu_del_vm_change_state_handler(blk->vmsh);
 483         blk->vmsh = NULL;
 484     }
 485     assert(QLIST_EMPTY(&blk->remove_bs_notifiers.notifiers));
 486     assert(QLIST_EMPTY(&blk->insert_bs_notifiers.notifiers));
 487     assert(QLIST_EMPTY(&blk->aio_notifiers));
 488     QTAILQ_REMOVE(&block_backends, blk, link);
 489     drive_info_del(blk->legacy_dinfo);
 490     block_acct_cleanup(&blk->stats);
 491     g_free(blk);
 492 }
 493
 494 static void drive_info_del(DriveInfo *dinfo)
 495 {
 496     if (!dinfo) {
 497         return;
 498     }
 499     qemu_opts_del(dinfo->opts);
 500     g_free(dinfo);
 501 }
 502
 503 int blk_get_refcnt(BlockBackend *blk)
 504 {
 505     GLOBAL_STATE_CODE();
 506     return blk ? blk->refcnt : 0;
 507 }
 508
 509 /*
 510  * Increment @blk's reference count.
 511  * @blk must not be null.
 512  */
 513 void blk_ref(BlockBackend *blk)
 514 {
 515     assert(blk->refcnt > 0);
 516     GLOBAL_STATE_CODE();
 517     blk->refcnt++;
 518 }
 519
 520 /*
 521  * Decrement @blk's reference count.
 522  * If this drops it to zero, destroy @blk.
 523  * For convenience, do nothing if @blk is null.
 524  */
 525 void blk_unref(BlockBackend *blk)
 526 {
 527     GLOBAL_STATE_CODE();
 528     if (blk) {
 529         assert(blk->refcnt > 0);
 530         if (blk->refcnt > 1) {
 531             blk->refcnt--;
 532         } else {
 533             blk_drain(blk);
 534             /* blk_drain() cannot resurrect blk, nobody held a reference */
 535             assert(blk->refcnt == 1);
 536             blk->refcnt = 0;
 537             blk_delete(blk);
 538         }
 539     }
 540 }
 541
 542 /*
 543  * Behaves similarly to blk_next() but iterates over all BlockBackends, even the
 544  * ones which are hidden (i.e. are not referenced by the monitor).
 545  */
 546 BlockBackend *blk_all_next(BlockBackend *blk)
 547 {
 548     GLOBAL_STATE_CODE();
 549     return blk ? QTAILQ_NEXT(blk, link)
 550                : QTAILQ_FIRST(&block_backends);
 551 }
 552
 553 void blk_remove_all_bs(void)
 554 {
 555     BlockBackend *blk = NULL;
 556
 557     GLOBAL_STATE_CODE();
 558
 559     while ((blk = blk_all_next(blk)) != NULL) {
 560         AioContext *ctx = blk_get_aio_context(blk);
 561
 562         aio_context_acquire(ctx);
 563         if (blk->root) {
 564             blk_remove_bs(blk);
 565         }
 566         aio_context_release(ctx);
 567     }
 568 }
 569
 570 /*
 571  * Return the monitor-owned BlockBackend after @blk.
 572  * If @blk is null, return the first one.
 573  * Else, return @blk's next sibling, which may be null.
 574  *
 575  * To iterate over all BlockBackends, do
 576  * for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
 577  *     ...
 578  * }
 579  */
 580 BlockBackend *blk_next(BlockBackend *blk)
 581 {
 582     GLOBAL_STATE_CODE();
 583     return blk ? QTAILQ_NEXT(blk, monitor_link)
 584                : QTAILQ_FIRST(&monitor_block_backends);
 585 }
 586
 587 /* Iterates over all top-level BlockDriverStates, i.e. BDSs that are owned by
 588  * the monitor or attached to a BlockBackend */
 589 BlockDriverState *bdrv_next(BdrvNextIterator *it)
 590 {
 591     BlockDriverState *bs, *old_bs;
 592
 593     /* Must be called from the main loop */
 594     assert(qemu_get_current_aio_context() == qemu_get_aio_context());
 595
 596     /* First, return all root nodes of BlockBackends. In order to avoid
 597      * returning a BDS twice when multiple BBs refer to it, we only return it
 598      * if the BB is the first one in the parent list of the BDS. */
 599     if (it->phase == BDRV_NEXT_BACKEND_ROOTS) {
 600         BlockBackend *old_blk = it->blk;
 601
 602         old_bs = old_blk ? blk_bs(old_blk) : NULL;
 603
 604         do {
 605             it->blk = blk_all_next(it->blk);
 606             bs = it->blk ? blk_bs(it->blk) : NULL;
 607         } while (it->blk && (bs == NULL || bdrv_first_blk(bs) != it->blk));
 608
 609         if (it->blk) {
 610             blk_ref(it->blk);
 611         }
 612         blk_unref(old_blk);
 613
 614         if (bs) {
 615             bdrv_ref(bs);
 616             bdrv_unref(old_bs);
 617             return bs;
 618         }
 619         it->phase = BDRV_NEXT_MONITOR_OWNED;
 620     } else {
 621         old_bs = it->bs;
 622     }
 623
 624     /* Then return the monitor-owned BDSes without a BB attached. Ignore all
 625      * BDSes that are attached to a BlockBackend here; they have been handled
 626      * by the above block already */
 627     do {
 628         it->bs = bdrv_next_monitor_owned(it->bs);
 629         bs = it->bs;
 630     } while (bs && bdrv_has_blk(bs));
 631
 632     if (bs) {
 633         bdrv_ref(bs);
 634     }
 635     bdrv_unref(old_bs);
 636
 637     return bs;
 638 }
 639
 640 static void bdrv_next_reset(BdrvNextIterator *it)
 641 {
 642     *it = (BdrvNextIterator) {
 643         .phase = BDRV_NEXT_BACKEND_ROOTS,
 644     };
 645 }
 646
 647 BlockDriverState *bdrv_first(BdrvNextIterator *it)
 648 {
 649     GLOBAL_STATE_CODE();
 650     bdrv_next_reset(it);
 651     return bdrv_next(it);
 652 }
 653
 654 /* Must be called when aborting a bdrv_next() iteration before
 655  * bdrv_next() returns NULL */
 656 void bdrv_next_cleanup(BdrvNextIterator *it)
 657 {
 658     /* Must be called from the main loop */
 659     assert(qemu_get_current_aio_context() == qemu_get_aio_context());
 660
 661     if (it->phase == BDRV_NEXT_BACKEND_ROOTS) {
 662         if (it->blk) {
 663             bdrv_unref(blk_bs(it->blk));
 664             blk_unref(it->blk);
 665         }
 666     } else {
 667         bdrv_unref(it->bs);
 668     }
 669
 670     bdrv_next_reset(it);
 671 }
 672
 673 /*
 674  * Add a BlockBackend into the list of backends referenced by the monitor, with
 675  * the given @name acting as the handle for the monitor.
 676  * Strictly for use by blockdev.c.
 677  *
 678  * @name must not be null or empty.
 679  *
 680  * Returns true on success and false on failure. In the latter case, an Error
 681  * object is returned through @errp.
 682  */
 683 bool monitor_add_blk(BlockBackend *blk, const char *name, Error **errp)
 684 {
 685     assert(!blk->name);
 686     assert(name && name[0]);
 687     GLOBAL_STATE_CODE();
 688
 689     if (!id_wellformed(name)) {
 690         error_setg(errp, "Invalid device name");
 691         return false;
 692     }
 693     if (blk_by_name(name)) {
 694         error_setg(errp, "Device with id '%s' already exists", name);
 695         return false;
 696     }
 697     if (bdrv_find_node(name)) {
 698         error_setg(errp,
 699                    "Device name '%s' conflicts with an existing node name",
 700                    name);
 701         return false;
 702     }
 703
 704     blk->name = g_strdup(name);
 705     QTAILQ_INSERT_TAIL(&monitor_block_backends, blk, monitor_link);
 706     return true;
 707 }
 708
 709 /*
 710  * Remove a BlockBackend from the list of backends referenced by the monitor.
 711  * Strictly for use by blockdev.c.
 712  */
 713 void monitor_remove_blk(BlockBackend *blk)
 714 {
 715     GLOBAL_STATE_CODE();
 716
 717     if (!blk->name) {
 718         return;
 719     }
 720
 721     QTAILQ_REMOVE(&monitor_block_backends, blk, monitor_link);
 722     g_free(blk->name);
 723     blk->name = NULL;
 724 }
 725
 726 /*
 727  * Return @blk's name, a non-null string.
 728  * Returns an empty string iff @blk is not referenced by the monitor.
 729  */
 730 const char *blk_name(const BlockBackend *blk)
 731 {
 732     IO_CODE();
 733     return blk->name ?: "";
 734 }
 735
 736 /*
 737  * Return the BlockBackend with name @name if it exists, else null.
 738  * @name must not be null.
 739  */
 740 BlockBackend *blk_by_name(const char *name)
 741 {
 742     BlockBackend *blk = NULL;
 743
 744     GLOBAL_STATE_CODE();
 745     assert(name);
 746     while ((blk = blk_next(blk)) != NULL) {
 747         if (!strcmp(name, blk->name)) {
 748             return blk;
 749         }
 750     }
 751     return NULL;
 752 }
 753
 754 /*
 755  * Return the BlockDriverState attached to @blk if any, else null.
 756  */
 757 BlockDriverState *blk_bs(BlockBackend *blk)
 758 {
 759     IO_CODE();
 760     return blk->root ? blk->root->bs : NULL;
 761 }
 762
 763 static BlockBackend *bdrv_first_blk(BlockDriverState *bs)
 764 {
 765     BdrvChild *child;
 766
 767     GLOBAL_STATE_CODE();
 768
 769     QLIST_FOREACH(child, &bs->parents, next_parent) {
 770         if (child->klass == &child_root) {
 771             return child->opaque;
 772         }
 773     }
 774
 775     return NULL;
 776 }
 777
 778 /*
 779  * Returns true if @bs has an associated BlockBackend.
 780  */
 781 bool bdrv_has_blk(BlockDriverState *bs)
 782 {
 783     GLOBAL_STATE_CODE();
 784     return bdrv_first_blk(bs) != NULL;
 785 }
 786
 787 /*
 788  * Returns true if @bs has only BlockBackends as parents.
 789  */
 790 bool bdrv_is_root_node(BlockDriverState *bs)
 791 {
 792     BdrvChild *c;
 793
 794     GLOBAL_STATE_CODE();
 795     QLIST_FOREACH(c, &bs->parents, next_parent) {
 796         if (c->klass != &child_root) {
 797             return false;
 798         }
 799     }
 800
 801     return true;
 802 }
 803
 804 /*
 805  * Return @blk's DriveInfo if any, else null.
 806  */
 807 DriveInfo *blk_legacy_dinfo(BlockBackend *blk)
 808 {
 809     GLOBAL_STATE_CODE();
 810     return blk->legacy_dinfo;
 811 }
 812
 813 /*
 814  * Set @blk's DriveInfo to @dinfo, and return it.
 815  * @blk must not have a DriveInfo set already.
 816  * No other BlockBackend may have the same DriveInfo set.
 817  */
 818 DriveInfo *blk_set_legacy_dinfo(BlockBackend *blk, DriveInfo *dinfo)
 819 {
 820     assert(!blk->legacy_dinfo);
 821     GLOBAL_STATE_CODE();
 822     return blk->legacy_dinfo = dinfo;
 823 }
 824
 825 /*
 826  * Return the BlockBackend with DriveInfo @dinfo.
 827  * It must exist.
 828  */
 829 BlockBackend *blk_by_legacy_dinfo(DriveInfo *dinfo)
 830 {
 831     BlockBackend *blk = NULL;
 832     GLOBAL_STATE_CODE();
 833
 834     while ((blk = blk_next(blk)) != NULL) {
 835         if (blk->legacy_dinfo == dinfo) {
 836             return blk;
 837         }
 838     }
 839     abort();
 840 }
 841
 842 /*
 843  * Returns a pointer to the publicly accessible fields of @blk.
 844  */
 845 BlockBackendPublic *blk_get_public(BlockBackend *blk)
 846 {
 847     GLOBAL_STATE_CODE();
 848     return &blk->public;
 849 }
 850
 851 /*
 852  * Returns a BlockBackend given the associated @public fields.
 853  */
 854 BlockBackend *blk_by_public(BlockBackendPublic *public)
 855 {
 856     GLOBAL_STATE_CODE();
 857     return container_of(public, BlockBackend, public);
 858 }
 859
 860 /*
 861  * Disassociates the currently associated BlockDriverState from @blk.
 862  */
 863 void blk_remove_bs(BlockBackend *blk)
 864 {
 865     ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
 866     BdrvChild *root;
 867
 868     GLOBAL_STATE_CODE();
 869
 870     notifier_list_notify(&blk->remove_bs_notifiers, blk);
 871     if (tgm->throttle_state) {
 872         BlockDriverState *bs = blk_bs(blk);
 873
 874         /*
 875          * Take a ref in case blk_bs() changes across bdrv_drained_begin(), for
 876          * example, if a temporary filter node is removed by a blockjob.
 877          */
 878         bdrv_ref(bs);
 879         bdrv_drained_begin(bs);
 880         throttle_group_detach_aio_context(tgm);
 881         throttle_group_attach_aio_context(tgm, qemu_get_aio_context());
 882         bdrv_drained_end(bs);
 883         bdrv_unref(bs);
 884     }
 885
 886     blk_update_root_state(blk);
 887
 888     /* bdrv_root_unref_child() will cause blk->root to become stale and may
 889      * switch to a completion coroutine later on. Let's drain all I/O here
 890      * to avoid that and a potential QEMU crash.
 891      */
 892     blk_drain(blk);
 893     root = blk->root;
 894     blk->root = NULL;
 895     bdrv_root_unref_child(root);
 896 }
 897
 898 /*
 899  * Associates a new BlockDriverState with @blk.
 900  */
 901 int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error **errp)
 902 {
 903     ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
 904     GLOBAL_STATE_CODE();
 905     bdrv_ref(bs);
 906     blk->root = bdrv_root_attach_child(bs, "root", &child_root,
 907                                        BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
 908                                        blk->perm, blk->shared_perm,
 909                                        blk, errp);
 910     if (blk->root == NULL) {
 911         return -EPERM;
 912     }
 913
 914     notifier_list_notify(&blk->insert_bs_notifiers, blk);
 915     if (tgm->throttle_state) {
 916         throttle_group_detach_aio_context(tgm);
 917         throttle_group_attach_aio_context(tgm, bdrv_get_aio_context(bs));
 918     }
 919
 920     return 0;
 921 }
 922
 923 /*
 924  * Change BlockDriverState associated with @blk.
 925  */
 926 int blk_replace_bs(BlockBackend *blk, BlockDriverState *new_bs, Error **errp)
 927 {
 928     GLOBAL_STATE_CODE();
 929     return bdrv_replace_child_bs(blk->root, new_bs, errp);
 930 }
 931
 932 /*
 933  * Sets the permission bitmasks that the user of the BlockBackend needs.
 934  */
 935 int blk_set_perm(BlockBackend *blk, uint64_t perm, uint64_t shared_perm,
 936                  Error **errp)
 937 {
 938     int ret;
 939     GLOBAL_STATE_CODE();
 940
 941     if (blk->root && !blk->disable_perm) {
 942         ret = bdrv_child_try_set_perm(blk->root, perm, shared_perm, errp);
 943         if (ret < 0) {
 944             return ret;
 945         }
 946     }
 947
 948     blk->perm = perm;
 949     blk->shared_perm = shared_perm;
 950
 951     return 0;
 952 }
 953
 954 void blk_get_perm(BlockBackend *blk, uint64_t *perm, uint64_t *shared_perm)
 955 {
 956     GLOBAL_STATE_CODE();
 957     *perm = blk->perm;
 958     *shared_perm = blk->shared_perm;
 959 }
 960
 961 /*
 962  * Attach device model @dev to @blk.
 963  * Return 0 on success, -EBUSY when a device model is attached already.
 964  */
 965 int blk_attach_dev(BlockBackend *blk, DeviceState *dev)
 966 {
 967     GLOBAL_STATE_CODE();
 968     if (blk->dev) {
 969         return -EBUSY;
 970     }
 971
 972     /* While migration is still incoming, we don't need to apply the
 973      * permissions of guest device BlockBackends. We might still have a block
 974      * job or NBD server writing to the image for storage migration. */
 975     if (runstate_check(RUN_STATE_INMIGRATE)) {
 976         blk->disable_perm = true;
 977     }
 978
 979     blk_ref(blk);
 980     blk->dev = dev;
 981     blk_iostatus_reset(blk);
 982
 983     return 0;
 984 }
 985
 986 /*
 987  * Detach device model @dev from @blk.
 988  * @dev must be currently attached to @blk.
 989  */
 990 void blk_detach_dev(BlockBackend *blk, DeviceState *dev)
 991 {
 992     assert(blk->dev == dev);
 993     GLOBAL_STATE_CODE();
 994     blk->dev = NULL;
 995     blk->dev_ops = NULL;
 996     blk->dev_opaque = NULL;
 997     blk_set_perm(blk, 0, BLK_PERM_ALL, &error_abort);
 998     blk_unref(blk);
 999 }
1000
1001 /*
1002  * Return the device model attached to @blk if any, else null.
1003  */
1004 DeviceState *blk_get_attached_dev(BlockBackend *blk)
1005 {
1006     GLOBAL_STATE_CODE();
1007     return blk->dev;
1008 }
1009
1010 /* Return the qdev ID, or if no ID is assigned the QOM path, of the block
1011  * device attached to the BlockBackend. */
1012 char *blk_get_attached_dev_id(BlockBackend *blk)
1013 {
1014     DeviceState *dev = blk->dev;
1015     IO_CODE();
1016
1017     if (!dev) {
1018         return g_strdup("");
1019     } else if (dev->id) {
1020         return g_strdup(dev->id);
1021     }
1022
1023     return object_get_canonical_path(OBJECT(dev)) ?: g_strdup("");
1024 }
1025
1026 /*
1027  * Return the BlockBackend which has the device model @dev attached if it
1028  * exists, else null.
1029  *
1030  * @dev must not be null.
1031  */
1032 BlockBackend *blk_by_dev(void *dev)
1033 {
1034     BlockBackend *blk = NULL;
1035
1036     GLOBAL_STATE_CODE();
1037
1038     assert(dev != NULL);
1039     while ((blk = blk_all_next(blk)) != NULL) {
1040         if (blk->dev == dev) {
1041             return blk;
1042         }
1043     }
1044     return NULL;
1045 }
1046
1047 /*
1048  * Set @blk's device model callbacks to @ops.
1049  * @opaque is the opaque argument to pass to the callbacks.
1050  * This is for use by device models.
1051  */
1052 void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops,
1053                      void *opaque)
1054 {
1055     GLOBAL_STATE_CODE();
1056     blk->dev_ops = ops;
1057     blk->dev_opaque = opaque;
1058
1059     /* Are we currently quiesced? Should we enforce this right now? */
1060     if (blk->quiesce_counter && ops && ops->drained_begin) {
1061         ops->drained_begin(opaque);
1062     }
1063 }
1064
1065 /*
1066  * Notify @blk's attached device model of media change.
1067  *
1068  * If @load is true, notify of media load. This action can fail, meaning that
1069  * the medium cannot be loaded. @errp is set then.
1070  *
1071  * If @load is false, notify of media eject. This can never fail.
1072  *
1073  * Also send DEVICE_TRAY_MOVED events as appropriate.
1074  */
1075 void blk_dev_change_media_cb(BlockBackend *blk, bool load, Error **errp)
1076 {
1077     GLOBAL_STATE_CODE();
1078     if (blk->dev_ops && blk->dev_ops->change_media_cb) {
1079         bool tray_was_open, tray_is_open;
1080         Error *local_err = NULL;
1081
1082         tray_was_open = blk_dev_is_tray_open(blk);
1083         blk->dev_ops->change_media_cb(blk->dev_opaque, load, &local_err);
1084         if (local_err) {
1085             assert(load == true);
1086             error_propagate(errp, local_err);
1087             return;
1088         }
1089         tray_is_open = blk_dev_is_tray_open(blk);
1090
1091         if (tray_was_open != tray_is_open) {
1092             char *id = blk_get_attached_dev_id(blk);
1093             qapi_event_send_device_tray_moved(blk_name(blk), id, tray_is_open);
1094             g_free(id);
1095         }
1096     }
1097 }
1098
1099 static void blk_root_change_media(BdrvChild *child, bool load)
1100 {
1101     blk_dev_change_media_cb(child->opaque, load, NULL);
1102 }
1103
1104 /*
1105  * Does @blk's attached device model have removable media?
1106  * %true if no device model is attached.
1107  */
1108 bool blk_dev_has_removable_media(BlockBackend *blk)
1109 {
1110     GLOBAL_STATE_CODE();
1111     return !blk->dev || (blk->dev_ops && blk->dev_ops->change_media_cb);
1112 }
1113
1114 /*
1115  * Does @blk's attached device model have a tray?
1116  */
1117 bool blk_dev_has_tray(BlockBackend *blk)
1118 {
1119     IO_CODE();
1120     return blk->dev_ops && blk->dev_ops->is_tray_open;
1121 }
1122
1123 /*
1124  * Notify @blk's attached device model of a media eject request.
1125  * If @force is true, the medium is about to be yanked out forcefully.
1126  */
1127 void blk_dev_eject_request(BlockBackend *blk, bool force)
1128 {
1129     GLOBAL_STATE_CODE();
1130     if (blk->dev_ops && blk->dev_ops->eject_request_cb) {
1131         blk->dev_ops->eject_request_cb(blk->dev_opaque, force);
1132     }
1133 }
1134
1135 /*
1136  * Does @blk's attached device model have a tray, and is it open?
1137  */
1138 bool blk_dev_is_tray_open(BlockBackend *blk)
1139 {
1140     IO_CODE();
1141     if (blk_dev_has_tray(blk)) {
1142         return blk->dev_ops->is_tray_open(blk->dev_opaque);
1143     }
1144     return false;
1145 }
1146
1147 /*
1148  * Does @blk's attached device model have the medium locked?
1149  * %false if the device model has no such lock.
1150  */
1151 bool blk_dev_is_medium_locked(BlockBackend *blk)
1152 {
1153     GLOBAL_STATE_CODE();
1154     if (blk->dev_ops && blk->dev_ops->is_medium_locked) {
1155         return blk->dev_ops->is_medium_locked(blk->dev_opaque);
1156     }
1157     return false;
1158 }
1159
1160 /*
1161  * Notify @blk's attached device model of a backend size change.
1162  */
1163 static void blk_root_resize(BdrvChild *child)
1164 {
1165     BlockBackend *blk = child->opaque;
1166
1167     if (blk->dev_ops && blk->dev_ops->resize_cb) {
1168         blk->dev_ops->resize_cb(blk->dev_opaque);
1169     }
1170 }
1171
1172 void blk_iostatus_enable(BlockBackend *blk)
1173 {
1174     GLOBAL_STATE_CODE();
1175     blk->iostatus_enabled = true;
1176     blk->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
1177 }
1178
1179 /* The I/O status is only enabled if the drive explicitly
1180  * enables it _and_ the VM is configured to stop on errors */
1181 bool blk_iostatus_is_enabled(const BlockBackend *blk)
1182 {
1183     IO_CODE();
1184     return (blk->iostatus_enabled &&
1185            (blk->on_write_error == BLOCKDEV_ON_ERROR_ENOSPC ||
1186             blk->on_write_error == BLOCKDEV_ON_ERROR_STOP   ||
1187             blk->on_read_error == BLOCKDEV_ON_ERROR_STOP));
1188 }
1189
1190 BlockDeviceIoStatus blk_iostatus(const BlockBackend *blk)
1191 {
1192     GLOBAL_STATE_CODE();
1193     return blk->iostatus;
1194 }
1195
1196 void blk_iostatus_disable(BlockBackend *blk)
1197 {
1198     GLOBAL_STATE_CODE();
1199     blk->iostatus_enabled = false;
1200 }
1201
1202 void blk_iostatus_reset(BlockBackend *blk)
1203 {
1204     GLOBAL_STATE_CODE();
1205     if (blk_iostatus_is_enabled(blk)) {
1206         blk->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
1207     }
1208 }
1209
1210 void blk_iostatus_set_err(BlockBackend *blk, int error)
1211 {
1212     IO_CODE();
1213     assert(blk_iostatus_is_enabled(blk));
1214     if (blk->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
1215         blk->iostatus = error == ENOSPC ? BLOCK_DEVICE_IO_STATUS_NOSPACE :
1216                                           BLOCK_DEVICE_IO_STATUS_FAILED;
1217     }
1218 }
1219
1220 void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow)
1221 {
1222     IO_CODE();
1223     blk->allow_write_beyond_eof = allow;
1224 }
1225
1226 void blk_set_allow_aio_context_change(BlockBackend *blk, bool allow)
1227 {
1228     IO_CODE();
1229     blk->allow_aio_context_change = allow;
1230 }
1231
1232 void blk_set_disable_request_queuing(BlockBackend *blk, bool disable)
1233 {
1234     IO_CODE();
1235     blk->disable_request_queuing = disable;
1236 }
1237
1238 static int blk_check_byte_request(BlockBackend *blk, int64_t offset,
1239                                   int64_t bytes)
1240 {
1241     int64_t len;
1242
1243     if (bytes < 0) {
1244         return -EIO;
1245     }
1246
1247     if (!blk_is_available(blk)) {
1248         return -ENOMEDIUM;
1249     }
1250
1251     if (offset < 0) {
1252         return -EIO;
1253     }
1254
1255     if (!blk->allow_write_beyond_eof) {
1256         len = blk_getlength(blk);
1257         if (len < 0) {
1258             return len;
1259         }
1260
1261         if (offset > len || len - offset < bytes) {
1262             return -EIO;
1263         }
1264     }
1265
1266     return 0;
1267 }
1268
1269 /* To be called between exactly one pair of blk_inc/dec_in_flight() */
1270 static void coroutine_fn blk_wait_while_drained(BlockBackend *blk)
1271 {
1272     assert(blk->in_flight > 0);
1273
1274     if (blk->quiesce_counter && !blk->disable_request_queuing) {
1275         blk_dec_in_flight(blk);
1276         qemu_co_queue_wait(&blk->queued_requests, NULL);
1277         blk_inc_in_flight(blk);
1278     }
1279 }
1280
1281 /* To be called between exactly one pair of blk_inc/dec_in_flight() */
1282 static int coroutine_fn
1283 blk_co_do_preadv_part(BlockBackend *blk, int64_t offset, int64_t bytes,
1284                       QEMUIOVector *qiov, size_t qiov_offset,
1285                       BdrvRequestFlags flags)
1286 {
1287     int ret;
1288     BlockDriverState *bs;
1289     IO_CODE();
1290
1291     blk_wait_while_drained(blk);
1292
1293     /* Call blk_bs() only after waiting, the graph may have changed */
1294     bs = blk_bs(blk);
1295     trace_blk_co_preadv(blk, bs, offset, bytes, flags);
1296
1297     ret = blk_check_byte_request(blk, offset, bytes);
1298     if (ret < 0) {
1299         return ret;
1300     }
1301
1302     bdrv_inc_in_flight(bs);
1303
1304     /* throttling disk I/O */
1305     if (blk->public.throttle_group_member.throttle_state) {
1306         throttle_group_co_io_limits_intercept(&blk->public.throttle_group_member,
1307                 bytes, false);
1308     }
1309
1310     ret = bdrv_co_preadv_part(blk->root, offset, bytes, qiov, qiov_offset,
1311                               flags);
1312     bdrv_dec_in_flight(bs);
1313     return ret;
1314 }
1315
1316 int coroutine_fn blk_co_pread(BlockBackend *blk, int64_t offset, int64_t bytes,
1317                               void *buf, BdrvRequestFlags flags)
1318 {
1319     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
1320     IO_OR_GS_CODE();
1321
1322     assert(bytes <= SIZE_MAX);
1323
1324     return blk_co_preadv(blk, offset, bytes, &qiov, flags);
1325 }
1326
1327 int coroutine_fn blk_co_preadv(BlockBackend *blk, int64_t offset,
1328                                int64_t bytes, QEMUIOVector *qiov,
1329                                BdrvRequestFlags flags)
1330 {
1331     int ret;
1332     IO_OR_GS_CODE();
1333
1334     blk_inc_in_flight(blk);
1335     ret = blk_co_do_preadv_part(blk, offset, bytes, qiov, 0, flags);
1336     blk_dec_in_flight(blk);
1337
1338     return ret;
1339 }
1340
1341 int coroutine_fn blk_co_preadv_part(BlockBackend *blk, int64_t offset,
1342                                     int64_t bytes, QEMUIOVector *qiov,
1343                                     size_t qiov_offset, BdrvRequestFlags flags)
1344 {
1345     int ret;
1346     IO_OR_GS_CODE();
1347
1348     blk_inc_in_flight(blk);
1349     ret = blk_co_do_preadv_part(blk, offset, bytes, qiov, qiov_offset, flags);
1350     blk_dec_in_flight(blk);
1351
1352     return ret;
1353 }
1354
1355 /* To be called between exactly one pair of blk_inc/dec_in_flight() */
1356 static int coroutine_fn
1357 blk_co_do_pwritev_part(BlockBackend *blk, int64_t offset, int64_t bytes,
1358                        QEMUIOVector *qiov, size_t qiov_offset,
1359                        BdrvRequestFlags flags)
1360 {
1361     int ret;
1362     BlockDriverState *bs;
1363     IO_CODE();
1364
1365     blk_wait_while_drained(blk);
1366
1367     /* Call blk_bs() only after waiting, the graph may have changed */
1368     bs = blk_bs(blk);
1369     trace_blk_co_pwritev(blk, bs, offset, bytes, flags);
1370
1371     ret = blk_check_byte_request(blk, offset, bytes);
1372     if (ret < 0) {
1373         return ret;
1374     }
1375
1376     bdrv_inc_in_flight(bs);
1377     /* throttling disk I/O */
1378     if (blk->public.throttle_group_member.throttle_state) {
1379         throttle_group_co_io_limits_intercept(&blk->public.throttle_group_member,
1380                 bytes, true);
1381     }
1382
1383     if (!blk->enable_write_cache) {
1384         flags |= BDRV_REQ_FUA;
1385     }
1386
1387     ret = bdrv_co_pwritev_part(blk->root, offset, bytes, qiov, qiov_offset,
1388                                flags);
1389     bdrv_dec_in_flight(bs);
1390     return ret;
1391 }
1392
1393 int coroutine_fn blk_co_pwritev_part(BlockBackend *blk, int64_t offset,
1394                                      int64_t bytes,
1395                                      QEMUIOVector *qiov, size_t qiov_offset,
1396                                      BdrvRequestFlags flags)
1397 {
1398     int ret;
1399     IO_OR_GS_CODE();
1400
1401     blk_inc_in_flight(blk);
1402     ret = blk_co_do_pwritev_part(blk, offset, bytes, qiov, qiov_offset, flags);
1403     blk_dec_in_flight(blk);
1404
1405     return ret;
1406 }
1407
1408 int coroutine_fn blk_co_pwrite(BlockBackend *blk, int64_t offset, int64_t bytes,
1409                                const void *buf, BdrvRequestFlags flags)
1410 {
1411     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
1412     IO_OR_GS_CODE();
1413
1414     assert(bytes <= SIZE_MAX);
1415
1416     return blk_co_pwritev(blk, offset, bytes, &qiov, flags);
1417 }
1418
1419 int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
1420                                 int64_t bytes, QEMUIOVector *qiov,
1421                                 BdrvRequestFlags flags)
1422 {
1423     IO_OR_GS_CODE();
1424     return blk_co_pwritev_part(blk, offset, bytes, qiov, 0, flags);
1425 }
1426
1427 typedef struct BlkRwCo {
1428     BlockBackend *blk;
1429     int64_t offset;
1430     void *iobuf;
1431     int ret;
1432     BdrvRequestFlags flags;
1433 } BlkRwCo;
1434
1435 int blk_make_zero(BlockBackend *blk, BdrvRequestFlags flags)
1436 {
1437     GLOBAL_STATE_CODE();
1438     return bdrv_make_zero(blk->root, flags);
1439 }
1440
1441 void blk_inc_in_flight(BlockBackend *blk)
1442 {
1443     IO_CODE();
1444     qatomic_inc(&blk->in_flight);
1445 }
1446
1447 void blk_dec_in_flight(BlockBackend *blk)
1448 {
1449     IO_CODE();
1450     qatomic_dec(&blk->in_flight);
1451     aio_wait_kick();
1452 }
1453
1454 static void error_callback_bh(void *opaque)
1455 {
1456     struct BlockBackendAIOCB *acb = opaque;
1457
1458     blk_dec_in_flight(acb->blk);
1459     acb->common.cb(acb->common.opaque, acb->ret);
1460     qemu_aio_unref(acb);
1461 }
1462
1463 BlockAIOCB *blk_abort_aio_request(BlockBackend *blk,
1464                                   BlockCompletionFunc *cb,
1465                                   void *opaque, int ret)
1466 {
1467     struct BlockBackendAIOCB *acb;
1468     IO_CODE();
1469
1470     blk_inc_in_flight(blk);
1471     acb = blk_aio_get(&block_backend_aiocb_info, blk, cb, opaque);
1472     acb->blk = blk;
1473     acb->ret = ret;
1474
1475     replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
1476                                      error_callback_bh, acb);
1477     return &acb->common;
1478 }
1479
1480 typedef struct BlkAioEmAIOCB {
1481     BlockAIOCB common;
1482     BlkRwCo rwco;
1483     int64_t bytes;
1484     bool has_returned;
1485 } BlkAioEmAIOCB;
1486
1487 static AioContext *blk_aio_em_aiocb_get_aio_context(BlockAIOCB *acb_)
1488 {
1489     BlkAioEmAIOCB *acb = container_of(acb_, BlkAioEmAIOCB, common);
1490
1491     return blk_get_aio_context(acb->rwco.blk);
1492 }
1493
1494 static const AIOCBInfo blk_aio_em_aiocb_info = {
1495     .aiocb_size         = sizeof(BlkAioEmAIOCB),
1496     .get_aio_context    = blk_aio_em_aiocb_get_aio_context,
1497 };
1498
1499 static void blk_aio_complete(BlkAioEmAIOCB *acb)
1500 {
1501     if (acb->has_returned) {
1502         acb->common.cb(acb->common.opaque, acb->rwco.ret);
1503         blk_dec_in_flight(acb->rwco.blk);
1504         qemu_aio_unref(acb);
1505     }
1506 }
1507
1508 static void blk_aio_complete_bh(void *opaque)
1509 {
1510     BlkAioEmAIOCB *acb = opaque;
1511     assert(acb->has_returned);
1512     blk_aio_complete(acb);
1513 }
1514
1515 static BlockAIOCB *blk_aio_prwv(BlockBackend *blk, int64_t offset,
1516                                 int64_t bytes,
1517                                 void *iobuf, CoroutineEntry co_entry,
1518                                 BdrvRequestFlags flags,
1519                                 BlockCompletionFunc *cb, void *opaque)
1520 {
1521     BlkAioEmAIOCB *acb;
1522     Coroutine *co;
1523
1524     blk_inc_in_flight(blk);
1525     acb = blk_aio_get(&blk_aio_em_aiocb_info, blk, cb, opaque);
1526     acb->rwco = (BlkRwCo) {
1527         .blk    = blk,
1528         .offset = offset,
1529         .iobuf  = iobuf,
1530         .flags  = flags,
1531         .ret    = NOT_DONE,
1532     };
1533     acb->bytes = bytes;
1534     acb->has_returned = false;
1535
1536     co = qemu_coroutine_create(co_entry, acb);
1537     bdrv_coroutine_enter(blk_bs(blk), co);
1538
1539     acb->has_returned = true;
1540     if (acb->rwco.ret != NOT_DONE) {
1541         replay_bh_schedule_oneshot_event(blk_get_aio_context(blk),
1542                                          blk_aio_complete_bh, acb);
1543     }
1544
1545     return &acb->common;
1546 }
1547
1548 static void coroutine_fn blk_aio_read_entry(void *opaque)
1549 {
1550     BlkAioEmAIOCB *acb = opaque;
1551     BlkRwCo *rwco = &acb->rwco;
1552     QEMUIOVector *qiov = rwco->iobuf;
1553
1554     assert(qiov->size == acb->bytes);
1555     rwco->ret = blk_co_do_preadv_part(rwco->blk, rwco->offset, acb->bytes, qiov,
1556                                       0, rwco->flags);
1557     blk_aio_complete(acb);
1558 }
1559
1560 static void coroutine_fn blk_aio_write_entry(void *opaque)
1561 {
1562     BlkAioEmAIOCB *acb = opaque;
1563     BlkRwCo *rwco = &acb->rwco;
1564     QEMUIOVector *qiov = rwco->iobuf;
1565
1566     assert(!qiov || qiov->size == acb->bytes);
1567     rwco->ret = blk_co_do_pwritev_part(rwco->blk, rwco->offset, acb->bytes,
1568                                        qiov, 0, rwco->flags);
1569     blk_aio_complete(acb);
1570 }
1571
1572 BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset,
1573                                   int64_t bytes, BdrvRequestFlags flags,
1574                                   BlockCompletionFunc *cb, void *opaque)
1575 {
1576     IO_CODE();
1577     return blk_aio_prwv(blk, offset, bytes, NULL, blk_aio_write_entry,
1578                         flags | BDRV_REQ_ZERO_WRITE, cb, opaque);
1579 }
1580
1581 int64_t blk_getlength(BlockBackend *blk)
1582 {
1583     IO_CODE();
1584     if (!blk_is_available(blk)) {
1585         return -ENOMEDIUM;
1586     }
1587
1588     return bdrv_getlength(blk_bs(blk));
1589 }
1590
1591 void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr)
1592 {
1593     IO_CODE();
1594     if (!blk_bs(blk)) {
1595         *nb_sectors_ptr = 0;
1596     } else {
1597         bdrv_get_geometry(blk_bs(blk), nb_sectors_ptr);
1598     }
1599 }
1600
1601 int64_t blk_nb_sectors(BlockBackend *blk)
1602 {
1603     IO_CODE();
1604     if (!blk_is_available(blk)) {
1605         return -ENOMEDIUM;
1606     }
1607
1608     return bdrv_nb_sectors(blk_bs(blk));
1609 }
1610
1611 BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
1612                            QEMUIOVector *qiov, BdrvRequestFlags flags,
1613                            BlockCompletionFunc *cb, void *opaque)
1614 {
1615     IO_CODE();
1616     assert((uint64_t)qiov->size <= INT64_MAX);
1617     return blk_aio_prwv(blk, offset, qiov->size, qiov,
1618                         blk_aio_read_entry, flags, cb, opaque);
1619 }
1620
1621 BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
1622                             QEMUIOVector *qiov, BdrvRequestFlags flags,
1623                             BlockCompletionFunc *cb, void *opaque)
1624 {
1625     IO_CODE();
1626     assert((uint64_t)qiov->size <= INT64_MAX);
1627     return blk_aio_prwv(blk, offset, qiov->size, qiov,
1628                         blk_aio_write_entry, flags, cb, opaque);
1629 }
1630
1631 void blk_aio_cancel(BlockAIOCB *acb)
1632 {
1633     GLOBAL_STATE_CODE();
1634     bdrv_aio_cancel(acb);
1635 }
1636
1637 void blk_aio_cancel_async(BlockAIOCB *acb)
1638 {
1639     IO_CODE();
1640     bdrv_aio_cancel_async(acb);
1641 }
1642
1643 /* To be called between exactly one pair of blk_inc/dec_in_flight() */
1644 static int coroutine_fn
1645 blk_co_do_ioctl(BlockBackend *blk, unsigned long int req, void *buf)
1646 {
1647     IO_CODE();
1648
1649     blk_wait_while_drained(blk);
1650
1651     if (!blk_is_available(blk)) {
1652         return -ENOMEDIUM;
1653     }
1654
1655     return bdrv_co_ioctl(blk_bs(blk), req, buf);
1656 }
1657
1658 int coroutine_fn blk_co_ioctl(BlockBackend *blk, unsigned long int req,
1659                               void *buf)
1660 {
1661     int ret;
1662     IO_OR_GS_CODE();
1663
1664     blk_inc_in_flight(blk);
1665     ret = blk_co_do_ioctl(blk, req, buf);
1666     blk_dec_in_flight(blk);
1667
1668     return ret;
1669 }
1670
1671 static void coroutine_fn blk_aio_ioctl_entry(void *opaque)
1672 {
1673     BlkAioEmAIOCB *acb = opaque;
1674     BlkRwCo *rwco = &acb->rwco;
1675
1676     rwco->ret = blk_co_do_ioctl(rwco->blk, rwco->offset, rwco->iobuf);
1677
1678     blk_aio_complete(acb);
1679 }
1680
1681 BlockAIOCB *blk_aio_ioctl(BlockBackend *blk, unsigned long int req, void *buf,
1682                           BlockCompletionFunc *cb, void *opaque)
1683 {
1684     IO_CODE();
1685     return blk_aio_prwv(blk, req, 0, buf, blk_aio_ioctl_entry, 0, cb, opaque);
1686 }
1687
1688 /* To be called between exactly one pair of blk_inc/dec_in_flight() */
1689 static int coroutine_fn
1690 blk_co_do_pdiscard(BlockBackend *blk, int64_t offset, int64_t bytes)
1691 {
1692     int ret;
1693     IO_CODE();
1694
1695     blk_wait_while_drained(blk);
1696
1697     ret = blk_check_byte_request(blk, offset, bytes);
1698     if (ret < 0) {
1699         return ret;
1700     }
1701
1702     return bdrv_co_pdiscard(blk->root, offset, bytes);
1703 }
1704
1705 static void coroutine_fn blk_aio_pdiscard_entry(void *opaque)
1706 {
1707     BlkAioEmAIOCB *acb = opaque;
1708     BlkRwCo *rwco = &acb->rwco;
1709
1710     rwco->ret = blk_co_do_pdiscard(rwco->blk, rwco->offset, acb->bytes);
1711     blk_aio_complete(acb);
1712 }
1713
1714 BlockAIOCB *blk_aio_pdiscard(BlockBackend *blk,
1715                              int64_t offset, int64_t bytes,
1716                              BlockCompletionFunc *cb, void *opaque)
1717 {
1718     IO_CODE();
1719     return blk_aio_prwv(blk, offset, bytes, NULL, blk_aio_pdiscard_entry, 0,
1720                         cb, opaque);
1721 }
1722
1723 int coroutine_fn blk_co_pdiscard(BlockBackend *blk, int64_t offset,
1724                                  int64_t bytes)
1725 {
1726     int ret;
1727     IO_OR_GS_CODE();
1728
1729     blk_inc_in_flight(blk);
1730     ret = blk_co_do_pdiscard(blk, offset, bytes);
1731     blk_dec_in_flight(blk);
1732
1733     return ret;
1734 }
1735
1736 /* To be called between exactly one pair of blk_inc/dec_in_flight() */
1737 static int coroutine_fn blk_co_do_flush(BlockBackend *blk)
1738 {
1739     blk_wait_while_drained(blk);
1740     IO_CODE();
1741
1742     if (!blk_is_available(blk)) {
1743         return -ENOMEDIUM;
1744     }
1745
1746     return bdrv_co_flush(blk_bs(blk));
1747 }
1748
1749 static void coroutine_fn blk_aio_flush_entry(void *opaque)
1750 {
1751     BlkAioEmAIOCB *acb = opaque;
1752     BlkRwCo *rwco = &acb->rwco;
1753
1754     rwco->ret = blk_co_do_flush(rwco->blk);
1755     blk_aio_complete(acb);
1756 }
1757
1758 BlockAIOCB *blk_aio_flush(BlockBackend *blk,
1759                           BlockCompletionFunc *cb, void *opaque)
1760 {
1761     IO_CODE();
1762     return blk_aio_prwv(blk, 0, 0, NULL, blk_aio_flush_entry, 0, cb, opaque);
1763 }
1764
1765 int coroutine_fn blk_co_flush(BlockBackend *blk)
1766 {
1767     int ret;
1768     IO_OR_GS_CODE();
1769
1770     blk_inc_in_flight(blk);
1771     ret = blk_co_do_flush(blk);
1772     blk_dec_in_flight(blk);
1773
1774     return ret;
1775 }
1776
1777 void blk_drain(BlockBackend *blk)
1778 {
1779     BlockDriverState *bs = blk_bs(blk);
1780     GLOBAL_STATE_CODE();
1781
1782     if (bs) {
1783         bdrv_ref(bs);
1784         bdrv_drained_begin(bs);
1785     }
1786
1787     /* We may have -ENOMEDIUM completions in flight */
1788     AIO_WAIT_WHILE(blk_get_aio_context(blk),
1789                    qatomic_mb_read(&blk->in_flight) > 0);
1790
1791     if (bs) {
1792         bdrv_drained_end(bs);
1793         bdrv_unref(bs);
1794     }
1795 }
1796
1797 void blk_drain_all(void)
1798 {
1799     BlockBackend *blk = NULL;
1800
1801     GLOBAL_STATE_CODE();
1802
1803     bdrv_drain_all_begin();
1804
1805     while ((blk = blk_all_next(blk)) != NULL) {
1806         AioContext *ctx = blk_get_aio_context(blk);
1807
1808         aio_context_acquire(ctx);
1809
1810         /* We may have -ENOMEDIUM completions in flight */
1811         AIO_WAIT_WHILE(ctx, qatomic_mb_read(&blk->in_flight) > 0);
1812
1813         aio_context_release(ctx);
1814     }
1815
1816     bdrv_drain_all_end();
1817 }
1818
1819 void blk_set_on_error(BlockBackend *blk, BlockdevOnError on_read_error,
1820                       BlockdevOnError on_write_error)
1821 {
1822     GLOBAL_STATE_CODE();
1823     blk->on_read_error = on_read_error;
1824     blk->on_write_error = on_write_error;
1825 }
1826
1827 BlockdevOnError blk_get_on_error(BlockBackend *blk, bool is_read)
1828 {
1829     IO_CODE();
1830     return is_read ? blk->on_read_error : blk->on_write_error;
1831 }
1832
1833 BlockErrorAction blk_get_error_action(BlockBackend *blk, bool is_read,
1834                                       int error)
1835 {
1836     BlockdevOnError on_err = blk_get_on_error(blk, is_read);
1837     IO_CODE();
1838
1839     switch (on_err) {
1840     case BLOCKDEV_ON_ERROR_ENOSPC:
1841         return (error == ENOSPC) ?
1842                BLOCK_ERROR_ACTION_STOP : BLOCK_ERROR_ACTION_REPORT;
1843     case BLOCKDEV_ON_ERROR_STOP:
1844         return BLOCK_ERROR_ACTION_STOP;
1845     case BLOCKDEV_ON_ERROR_REPORT:
1846         return BLOCK_ERROR_ACTION_REPORT;
1847     case BLOCKDEV_ON_ERROR_IGNORE:
1848         return BLOCK_ERROR_ACTION_IGNORE;
1849     case BLOCKDEV_ON_ERROR_AUTO:
1850     default:
1851         abort();
1852     }
1853 }
1854
1855 static void send_qmp_error_event(BlockBackend *blk,
1856                                  BlockErrorAction action,
1857                                  bool is_read, int error)
1858 {
1859     IoOperationType optype;
1860     BlockDriverState *bs = blk_bs(blk);
1861
1862     optype = is_read ? IO_OPERATION_TYPE_READ : IO_OPERATION_TYPE_WRITE;
1863     qapi_event_send_block_io_error(blk_name(blk), !!bs,
1864                                    bs ? bdrv_get_node_name(bs) : NULL, optype,
1865                                    action, blk_iostatus_is_enabled(blk),
1866                                    error == ENOSPC, strerror(error));
1867 }
1868
1869 /* This is done by device models because, while the block layer knows
1870  * about the error, it does not know whether an operation comes from
1871  * the device or the block layer (from a job, for example).
1872  */
1873 void blk_error_action(BlockBackend *blk, BlockErrorAction action,
1874                       bool is_read, int error)
1875 {
1876     assert(error >= 0);
1877     IO_CODE();
1878
1879     if (action == BLOCK_ERROR_ACTION_STOP) {
1880         /* First set the iostatus, so that "info block" returns an iostatus
1881          * that matches the events raised so far (an additional error iostatus
1882          * is fine, but not a lost one).
1883          */
1884         blk_iostatus_set_err(blk, error);
1885
1886         /* Then raise the request to stop the VM and the event.
1887          * qemu_system_vmstop_request_prepare has two effects.  First,
1888          * it ensures that the STOP event always comes after the
1889          * BLOCK_IO_ERROR event.  Second, it ensures that even if management
1890          * can observe the STOP event and do a "cont" before the STOP
1891          * event is issued, the VM will not stop.  In this case, vm_start()
1892          * also ensures that the STOP/RESUME pair of events is emitted.
1893          */
1894         qemu_system_vmstop_request_prepare();
1895         send_qmp_error_event(blk, action, is_read, error);
1896         qemu_system_vmstop_request(RUN_STATE_IO_ERROR);
1897     } else {
1898         send_qmp_error_event(blk, action, is_read, error);
1899     }
1900 }
1901
1902 /*
1903  * Returns true if the BlockBackend can support taking write permissions
1904  * (because its root node is not read-only).
1905  */
1906 bool blk_supports_write_perm(BlockBackend *blk)
1907 {
1908     BlockDriverState *bs = blk_bs(blk);
1909     GLOBAL_STATE_CODE();
1910
1911     if (bs) {
1912         return !bdrv_is_read_only(bs);
1913     } else {
1914         return blk->root_state.open_flags & BDRV_O_RDWR;
1915     }
1916 }
1917
1918 /*
1919  * Returns true if the BlockBackend can be written to in its current
1920  * configuration (i.e. if write permission have been requested)
1921  */
1922 bool blk_is_writable(BlockBackend *blk)
1923 {
1924     IO_CODE();
1925     return blk->perm & BLK_PERM_WRITE;
1926 }
1927
1928 bool blk_is_sg(BlockBackend *blk)
1929 {
1930     BlockDriverState *bs = blk_bs(blk);
1931     GLOBAL_STATE_CODE();
1932
1933     if (!bs) {
1934         return false;
1935     }
1936
1937     return bdrv_is_sg(bs);
1938 }
1939
1940 bool blk_enable_write_cache(BlockBackend *blk)
1941 {
1942     IO_CODE();
1943     return blk->enable_write_cache;
1944 }
1945
1946 void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
1947 {
1948     IO_CODE();
1949     blk->enable_write_cache = wce;
1950 }
1951
1952 void blk_activate(BlockBackend *blk, Error **errp)
1953 {
1954     BlockDriverState *bs = blk_bs(blk);
1955     GLOBAL_STATE_CODE();
1956
1957     if (!bs) {
1958         error_setg(errp, "Device '%s' has no medium", blk->name);
1959         return;
1960     }
1961
1962     bdrv_activate(bs, errp);
1963 }
1964
1965 bool blk_is_inserted(BlockBackend *blk)
1966 {
1967     BlockDriverState *bs = blk_bs(blk);
1968     IO_CODE();
1969
1970     return bs && bdrv_is_inserted(bs);
1971 }
1972
1973 bool blk_is_available(BlockBackend *blk)
1974 {
1975     IO_CODE();
1976     return blk_is_inserted(blk) && !blk_dev_is_tray_open(blk);
1977 }
1978
1979 void blk_lock_medium(BlockBackend *blk, bool locked)
1980 {
1981     BlockDriverState *bs = blk_bs(blk);
1982     IO_CODE();
1983
1984     if (bs) {
1985         bdrv_lock_medium(bs, locked);
1986     }
1987 }
1988
1989 void blk_eject(BlockBackend *blk, bool eject_flag)
1990 {
1991     BlockDriverState *bs = blk_bs(blk);
1992     char *id;
1993     IO_CODE();
1994
1995     if (bs) {
1996         bdrv_eject(bs, eject_flag);
1997     }
1998
1999     /* Whether or not we ejected on the backend,
2000      * the frontend experienced a tray event. */
2001     id = blk_get_attached_dev_id(blk);
2002     qapi_event_send_device_tray_moved(blk_name(blk), id,
2003                                       eject_flag);
2004     g_free(id);
2005 }
2006
2007 int blk_get_flags(BlockBackend *blk)
2008 {
2009     BlockDriverState *bs = blk_bs(blk);
2010     GLOBAL_STATE_CODE();
2011
2012     if (bs) {
2013         return bdrv_get_flags(bs);
2014     } else {
2015         return blk->root_state.open_flags;
2016     }
2017 }
2018
2019 /* Returns the minimum request alignment, in bytes; guaranteed nonzero */
2020 uint32_t blk_get_request_alignment(BlockBackend *blk)
2021 {
2022     BlockDriverState *bs = blk_bs(blk);
2023     IO_CODE();
2024     return bs ? bs->bl.request_alignment : BDRV_SECTOR_SIZE;
2025 }
2026
2027 /* Returns the maximum hardware transfer length, in bytes; guaranteed nonzero */
2028 uint64_t blk_get_max_hw_transfer(BlockBackend *blk)
2029 {
2030     BlockDriverState *bs = blk_bs(blk);
2031     uint64_t max = INT_MAX;
2032     IO_CODE();
2033
2034     if (bs) {
2035         max = MIN_NON_ZERO(max, bs->bl.max_hw_transfer);
2036         max = MIN_NON_ZERO(max, bs->bl.max_transfer);
2037     }
2038     return ROUND_DOWN(max, blk_get_request_alignment(blk));
2039 }
2040
2041 /* Returns the maximum transfer length, in bytes; guaranteed nonzero */
2042 uint32_t blk_get_max_transfer(BlockBackend *blk)
2043 {
2044     BlockDriverState *bs = blk_bs(blk);
2045     uint32_t max = INT_MAX;
2046     IO_CODE();
2047
2048     if (bs) {
2049         max = MIN_NON_ZERO(max, bs->bl.max_transfer);
2050     }
2051     return ROUND_DOWN(max, blk_get_request_alignment(blk));
2052 }
2053
2054 int blk_get_max_hw_iov(BlockBackend *blk)
2055 {
2056     IO_CODE();
2057     return MIN_NON_ZERO(blk->root->bs->bl.max_hw_iov,
2058                         blk->root->bs->bl.max_iov);
2059 }
2060
2061 int blk_get_max_iov(BlockBackend *blk)
2062 {
2063     IO_CODE();
2064     return blk->root->bs->bl.max_iov;
2065 }
2066
2067 void *blk_try_blockalign(BlockBackend *blk, size_t size)
2068 {
2069     IO_CODE();
2070     return qemu_try_blockalign(blk ? blk_bs(blk) : NULL, size);
2071 }
2072
2073 void *blk_blockalign(BlockBackend *blk, size_t size)
2074 {
2075     IO_CODE();
2076     return qemu_blockalign(blk ? blk_bs(blk) : NULL, size);
2077 }
2078
2079 bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp)
2080 {
2081     BlockDriverState *bs = blk_bs(blk);
2082     GLOBAL_STATE_CODE();
2083
2084     if (!bs) {
2085         return false;
2086     }
2087
2088     return bdrv_op_is_blocked(bs, op, errp);
2089 }
2090
2091 void blk_op_unblock(BlockBackend *blk, BlockOpType op, Error *reason)
2092 {
2093     BlockDriverState *bs = blk_bs(blk);
2094     GLOBAL_STATE_CODE();
2095
2096     if (bs) {
2097         bdrv_op_unblock(bs, op, reason);
2098     }
2099 }
2100
2101 void blk_op_block_all(BlockBackend *blk, Error *reason)
2102 {
2103     BlockDriverState *bs = blk_bs(blk);
2104     GLOBAL_STATE_CODE();
2105
2106     if (bs) {
2107         bdrv_op_block_all(bs, reason);
2108     }
2109 }
2110
2111 void blk_op_unblock_all(BlockBackend *blk, Error *reason)
2112 {
2113     BlockDriverState *bs = blk_bs(blk);
2114     GLOBAL_STATE_CODE();
2115
2116     if (bs) {
2117         bdrv_op_unblock_all(bs, reason);
2118     }
2119 }
2120
2121 AioContext *blk_get_aio_context(BlockBackend *blk)
2122 {
2123     BlockDriverState *bs = blk_bs(blk);
2124     IO_CODE();
2125
2126     if (bs) {
2127         AioContext *ctx = bdrv_get_aio_context(blk_bs(blk));
2128         assert(ctx == blk->ctx);
2129     }
2130
2131     return blk->ctx;
2132 }
2133
2134 static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb)
2135 {
2136     BlockBackendAIOCB *blk_acb = DO_UPCAST(BlockBackendAIOCB, common, acb);
2137     return blk_get_aio_context(blk_acb->blk);
2138 }
2139
2140 static int blk_do_set_aio_context(BlockBackend *blk, AioContext *new_context,
2141                                   bool update_root_node, Error **errp)
2142 {
2143     BlockDriverState *bs = blk_bs(blk);
2144     ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
2145     int ret;
2146
2147     if (bs) {
2148         bdrv_ref(bs);
2149
2150         if (update_root_node) {
2151             /*
2152              * update_root_node MUST be false for blk_root_set_aio_ctx_commit(),
2153              * as we are already in the commit function of a transaction.
2154              */
2155             ret = bdrv_try_change_aio_context(bs, new_context, blk->root, errp);
2156             if (ret < 0) {
2157                 bdrv_unref(bs);
2158                 return ret;
2159             }
2160         }
2161         /*
2162          * Make blk->ctx consistent with the root node before we invoke any
2163          * other operations like drain that might inquire blk->ctx
2164          */
2165         blk->ctx = new_context;
2166         if (tgm->throttle_state) {
2167             bdrv_drained_begin(bs);
2168             throttle_group_detach_aio_context(tgm);
2169             throttle_group_attach_aio_context(tgm, new_context);
2170             bdrv_drained_end(bs);
2171         }
2172
2173         bdrv_unref(bs);
2174     } else {
2175         blk->ctx = new_context;
2176     }
2177
2178     return 0;
2179 }
2180
2181 int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
2182                         Error **errp)
2183 {
2184     GLOBAL_STATE_CODE();
2185     return blk_do_set_aio_context(blk, new_context, true, errp);
2186 }
2187
2188 typedef struct BdrvStateBlkRootContext {
2189     AioContext *new_ctx;
2190     BlockBackend *blk;
2191 } BdrvStateBlkRootContext;
2192
2193 static void blk_root_set_aio_ctx_commit(void *opaque)
2194 {
2195     BdrvStateBlkRootContext *s = opaque;
2196     BlockBackend *blk = s->blk;
2197
2198     blk_do_set_aio_context(blk, s->new_ctx, false, &error_abort);
2199 }
2200
2201 static TransactionActionDrv set_blk_root_context = {
2202     .commit = blk_root_set_aio_ctx_commit,
2203     .clean = g_free,
2204 };
2205
2206 static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
2207                                     GHashTable *visited, Transaction *tran,
2208                                     Error **errp)
2209 {
2210     BlockBackend *blk = child->opaque;
2211     BdrvStateBlkRootContext *s;
2212
2213     if (!blk->allow_aio_context_change) {
2214         /*
2215          * Manually created BlockBackends (those with a name) that are not
2216          * attached to anything can change their AioContext without updating
2217          * their user; return an error for others.
2218          */
2219         if (!blk->name || blk->dev) {
2220             /* TODO Add BB name/QOM path */
2221             error_setg(errp, "Cannot change iothread of active block backend");
2222             return false;
2223         }
2224     }
2225
2226     s = g_new(BdrvStateBlkRootContext, 1);
2227     *s = (BdrvStateBlkRootContext) {
2228         .new_ctx = ctx,
2229         .blk = blk,
2230     };
2231
2232     tran_add(tran, &set_blk_root_context, s);
2233     return true;
2234 }
2235
2236 void blk_add_aio_context_notifier(BlockBackend *blk,
2237         void (*attached_aio_context)(AioContext *new_context, void *opaque),
2238         void (*detach_aio_context)(void *opaque), void *opaque)
2239 {
2240     BlockBackendAioNotifier *notifier;
2241     BlockDriverState *bs = blk_bs(blk);
2242     GLOBAL_STATE_CODE();
2243
2244     notifier = g_new(BlockBackendAioNotifier, 1);
2245     notifier->attached_aio_context = attached_aio_context;
2246     notifier->detach_aio_context = detach_aio_context;
2247     notifier->opaque = opaque;
2248     QLIST_INSERT_HEAD(&blk->aio_notifiers, notifier, list);
2249
2250     if (bs) {
2251         bdrv_add_aio_context_notifier(bs, attached_aio_context,
2252                                       detach_aio_context, opaque);
2253     }
2254 }
2255
2256 void blk_remove_aio_context_notifier(BlockBackend *blk,
2257                                      void (*attached_aio_context)(AioContext *,
2258                                                                   void *),
2259                                      void (*detach_aio_context)(void *),
2260                                      void *opaque)
2261 {
2262     BlockBackendAioNotifier *notifier;
2263     BlockDriverState *bs = blk_bs(blk);
2264
2265     GLOBAL_STATE_CODE();
2266
2267     if (bs) {
2268         bdrv_remove_aio_context_notifier(bs, attached_aio_context,
2269                                          detach_aio_context, opaque);
2270     }
2271
2272     QLIST_FOREACH(notifier, &blk->aio_notifiers, list) {
2273         if (notifier->attached_aio_context == attached_aio_context &&
2274             notifier->detach_aio_context == detach_aio_context &&
2275             notifier->opaque == opaque) {
2276             QLIST_REMOVE(notifier, list);
2277             g_free(notifier);
2278             return;
2279         }
2280     }
2281
2282     abort();
2283 }
2284
2285 void blk_add_remove_bs_notifier(BlockBackend *blk, Notifier *notify)
2286 {
2287     GLOBAL_STATE_CODE();
2288     notifier_list_add(&blk->remove_bs_notifiers, notify);
2289 }
2290
2291 void blk_add_insert_bs_notifier(BlockBackend *blk, Notifier *notify)
2292 {
2293     GLOBAL_STATE_CODE();
2294     notifier_list_add(&blk->insert_bs_notifiers, notify);
2295 }
2296
2297 void blk_io_plug(BlockBackend *blk)
2298 {
2299     BlockDriverState *bs = blk_bs(blk);
2300     IO_CODE();
2301
2302     if (bs) {
2303         bdrv_io_plug(bs);
2304     }
2305 }
2306
2307 void blk_io_unplug(BlockBackend *blk)
2308 {
2309     BlockDriverState *bs = blk_bs(blk);
2310     IO_CODE();
2311
2312     if (bs) {
2313         bdrv_io_unplug(bs);
2314     }
2315 }
2316
2317 BlockAcctStats *blk_get_stats(BlockBackend *blk)
2318 {
2319     IO_CODE();
2320     return &blk->stats;
2321 }
2322
2323 void *blk_aio_get(const AIOCBInfo *aiocb_info, BlockBackend *blk,
2324                   BlockCompletionFunc *cb, void *opaque)
2325 {
2326     IO_CODE();
2327     return qemu_aio_get(aiocb_info, blk_bs(blk), cb, opaque);
2328 }
2329
2330 int coroutine_fn blk_co_pwrite_zeroes(BlockBackend *blk, int64_t offset,
2331                                       int64_t bytes, BdrvRequestFlags flags)
2332 {
2333     IO_OR_GS_CODE();
2334     return blk_co_pwritev(blk, offset, bytes, NULL,
2335                           flags | BDRV_REQ_ZERO_WRITE);
2336 }
2337
2338 int coroutine_fn blk_co_pwrite_compressed(BlockBackend *blk, int64_t offset,
2339                                           int64_t bytes, const void *buf)
2340 {
2341     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
2342     IO_OR_GS_CODE();
2343     return blk_co_pwritev_part(blk, offset, bytes, &qiov, 0,
2344                                BDRV_REQ_WRITE_COMPRESSED);
2345 }
2346
2347 int coroutine_fn blk_co_truncate(BlockBackend *blk, int64_t offset, bool exact,
2348                                  PreallocMode prealloc, BdrvRequestFlags flags,
2349                                  Error **errp)
2350 {
2351     IO_OR_GS_CODE();
2352     if (!blk_is_available(blk)) {
2353         error_setg(errp, "No medium inserted");
2354         return -ENOMEDIUM;
2355     }
2356
2357     return bdrv_co_truncate(blk->root, offset, exact, prealloc, flags, errp);
2358 }
2359
2360 int blk_save_vmstate(BlockBackend *blk, const uint8_t *buf,
2361                      int64_t pos, int size)
2362 {
2363     int ret;
2364     GLOBAL_STATE_CODE();
2365
2366     if (!blk_is_available(blk)) {
2367         return -ENOMEDIUM;
2368     }
2369
2370     ret = bdrv_save_vmstate(blk_bs(blk), buf, pos, size);
2371     if (ret < 0) {
2372         return ret;
2373     }
2374
2375     if (ret == size && !blk->enable_write_cache) {
2376         ret = bdrv_flush(blk_bs(blk));
2377     }
2378
2379     return ret < 0 ? ret : size;
2380 }
2381
2382 int blk_load_vmstate(BlockBackend *blk, uint8_t *buf, int64_t pos, int size)
2383 {
2384     GLOBAL_STATE_CODE();
2385     if (!blk_is_available(blk)) {
2386         return -ENOMEDIUM;
2387     }
2388
2389     return bdrv_load_vmstate(blk_bs(blk), buf, pos, size);
2390 }
2391
2392 int blk_probe_blocksizes(BlockBackend *blk, BlockSizes *bsz)
2393 {
2394     GLOBAL_STATE_CODE();
2395     if (!blk_is_available(blk)) {
2396         return -ENOMEDIUM;
2397     }
2398
2399     return bdrv_probe_blocksizes(blk_bs(blk), bsz);
2400 }
2401
2402 int blk_probe_geometry(BlockBackend *blk, HDGeometry *geo)
2403 {
2404     GLOBAL_STATE_CODE();
2405     if (!blk_is_available(blk)) {
2406         return -ENOMEDIUM;
2407     }
2408
2409     return bdrv_probe_geometry(blk_bs(blk), geo);
2410 }
2411
2412 /*
2413  * Updates the BlockBackendRootState object with data from the currently
2414  * attached BlockDriverState.
2415  */
2416 void blk_update_root_state(BlockBackend *blk)
2417 {
2418     GLOBAL_STATE_CODE();
2419     assert(blk->root);
2420
2421     blk->root_state.open_flags    = blk->root->bs->open_flags;
2422     blk->root_state.detect_zeroes = blk->root->bs->detect_zeroes;
2423 }
2424
2425 /*
2426  * Returns the detect-zeroes setting to be used for bdrv_open() of a
2427  * BlockDriverState which is supposed to inherit the root state.
2428  */
2429 bool blk_get_detect_zeroes_from_root_state(BlockBackend *blk)
2430 {
2431     GLOBAL_STATE_CODE();
2432     return blk->root_state.detect_zeroes;
2433 }
2434
2435 /*
2436  * Returns the flags to be used for bdrv_open() of a BlockDriverState which is
2437  * supposed to inherit the root state.
2438  */
2439 int blk_get_open_flags_from_root_state(BlockBackend *blk)
2440 {
2441     GLOBAL_STATE_CODE();
2442     return blk->root_state.open_flags;
2443 }
2444
2445 BlockBackendRootState *blk_get_root_state(BlockBackend *blk)
2446 {
2447     GLOBAL_STATE_CODE();
2448     return &blk->root_state;
2449 }
2450
2451 int blk_commit_all(void)
2452 {
2453     BlockBackend *blk = NULL;
2454     GLOBAL_STATE_CODE();
2455
2456     while ((blk = blk_all_next(blk)) != NULL) {
2457         AioContext *aio_context = blk_get_aio_context(blk);
2458         BlockDriverState *unfiltered_bs = bdrv_skip_filters(blk_bs(blk));
2459
2460         aio_context_acquire(aio_context);
2461         if (blk_is_inserted(blk) && bdrv_cow_child(unfiltered_bs)) {
2462             int ret;
2463
2464             ret = bdrv_commit(unfiltered_bs);
2465             if (ret < 0) {
2466                 aio_context_release(aio_context);
2467                 return ret;
2468             }
2469         }
2470         aio_context_release(aio_context);
2471     }
2472     return 0;
2473 }
2474
2475
2476 /* throttling disk I/O limits */
2477 void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg)
2478 {
2479     GLOBAL_STATE_CODE();
2480     throttle_group_config(&blk->public.throttle_group_member, cfg);
2481 }
2482
2483 void blk_io_limits_disable(BlockBackend *blk)
2484 {
2485     BlockDriverState *bs = blk_bs(blk);
2486     ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
2487     assert(tgm->throttle_state);
2488     GLOBAL_STATE_CODE();
2489     if (bs) {
2490         bdrv_ref(bs);
2491         bdrv_drained_begin(bs);
2492     }
2493     throttle_group_unregister_tgm(tgm);
2494     if (bs) {
2495         bdrv_drained_end(bs);
2496         bdrv_unref(bs);
2497     }
2498 }
2499
2500 /* should be called before blk_set_io_limits if a limit is set */
2501 void blk_io_limits_enable(BlockBackend *blk, const char *group)
2502 {
2503     assert(!blk->public.throttle_group_member.throttle_state);
2504     GLOBAL_STATE_CODE();
2505     throttle_group_register_tgm(&blk->public.throttle_group_member,
2506                                 group, blk_get_aio_context(blk));
2507 }
2508
2509 void blk_io_limits_update_group(BlockBackend *blk, const char *group)
2510 {
2511     GLOBAL_STATE_CODE();
2512     /* this BB is not part of any group */
2513     if (!blk->public.throttle_group_member.throttle_state) {
2514         return;
2515     }
2516
2517     /* this BB is a part of the same group than the one we want */
2518     if (!g_strcmp0(throttle_group_get_name(&blk->public.throttle_group_member),
2519                 group)) {
2520         return;
2521     }
2522
2523     /* need to change the group this bs belong to */
2524     blk_io_limits_disable(blk);
2525     blk_io_limits_enable(blk, group);
2526 }
2527
2528 static void blk_root_drained_begin(BdrvChild *child)
2529 {
2530     BlockBackend *blk = child->opaque;
2531     ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
2532
2533     if (++blk->quiesce_counter == 1) {
2534         if (blk->dev_ops && blk->dev_ops->drained_begin) {
2535             blk->dev_ops->drained_begin(blk->dev_opaque);
2536         }
2537     }
2538
2539     /* Note that blk->root may not be accessible here yet if we are just
2540      * attaching to a BlockDriverState that is drained. Use child instead. */
2541
2542     if (qatomic_fetch_inc(&tgm->io_limits_disabled) == 0) {
2543         throttle_group_restart_tgm(tgm);
2544     }
2545 }
2546
2547 static bool blk_root_drained_poll(BdrvChild *child)
2548 {
2549     BlockBackend *blk = child->opaque;
2550     bool busy = false;
2551     assert(blk->quiesce_counter);
2552
2553     if (blk->dev_ops && blk->dev_ops->drained_poll) {
2554         busy = blk->dev_ops->drained_poll(blk->dev_opaque);
2555     }
2556     return busy || !!blk->in_flight;
2557 }
2558
2559 static void blk_root_drained_end(BdrvChild *child, int *drained_end_counter)
2560 {
2561     BlockBackend *blk = child->opaque;
2562     assert(blk->quiesce_counter);
2563
2564     assert(blk->public.throttle_group_member.io_limits_disabled);
2565     qatomic_dec(&blk->public.throttle_group_member.io_limits_disabled);
2566
2567     if (--blk->quiesce_counter == 0) {
2568         if (blk->dev_ops && blk->dev_ops->drained_end) {
2569             blk->dev_ops->drained_end(blk->dev_opaque);
2570         }
2571         while (qemu_co_enter_next(&blk->queued_requests, NULL)) {
2572             /* Resume all queued requests */
2573         }
2574     }
2575 }
2576
2577 bool blk_register_buf(BlockBackend *blk, void *host, size_t size, Error **errp)
2578 {
2579     GLOBAL_STATE_CODE();
2580     return bdrv_register_buf(blk_bs(blk), host, size, errp);
2581 }
2582
2583 void blk_unregister_buf(BlockBackend *blk, void *host, size_t size)
2584 {
2585     GLOBAL_STATE_CODE();
2586     bdrv_unregister_buf(blk_bs(blk), host, size);
2587 }
2588
2589 int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
2590                                    BlockBackend *blk_out, int64_t off_out,
2591                                    int64_t bytes, BdrvRequestFlags read_flags,
2592                                    BdrvRequestFlags write_flags)
2593 {
2594     int r;
2595     IO_CODE();
2596
2597     r = blk_check_byte_request(blk_in, off_in, bytes);
2598     if (r) {
2599         return r;
2600     }
2601     r = blk_check_byte_request(blk_out, off_out, bytes);
2602     if (r) {
2603         return r;
2604     }
2605     return bdrv_co_copy_range(blk_in->root, off_in,
2606                               blk_out->root, off_out,
2607                               bytes, read_flags, write_flags);
2608 }
2609
2610 const BdrvChild *blk_root(BlockBackend *blk)
2611 {
2612     GLOBAL_STATE_CODE();
2613     return blk->root;
2614 }
2615
2616 int blk_make_empty(BlockBackend *blk, Error **errp)
2617 {
2618     GLOBAL_STATE_CODE();
2619     if (!blk_is_available(blk)) {
2620         error_setg(errp, "No medium inserted");
2621         return -ENOMEDIUM;
2622     }
2623
2624     return bdrv_make_empty(blk->root, errp);
2625 }