1 /* 2 * QEMU System Emulator block driver 3 * 4 * Copyright (c) 2003 Fabrice Bellard 5 * Copyright (c) 2020 Virtuozzo International GmbH. 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to deal 9 * in the Software without restriction, including without limitation the rights 10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 11 * copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 23 * THE SOFTWARE. 24 */ 25 26 #include "qemu/osdep.h" 27 #include "block/trace.h" 28 #include "block/block_int.h" 29 #include "block/blockjob.h" 30 #include "block/dirty-bitmap.h" 31 #include "block/fuse.h" 32 #include "block/nbd.h" 33 #include "block/qdict.h" 34 #include "qemu/error-report.h" 35 #include "block/module_block.h" 36 #include "qemu/main-loop.h" 37 #include "qemu/module.h" 38 #include "qapi/error.h" 39 #include "qapi/qmp/qdict.h" 40 #include "qapi/qmp/qjson.h" 41 #include "qapi/qmp/qnull.h" 42 #include "qapi/qmp/qstring.h" 43 #include "qapi/qobject-output-visitor.h" 44 #include "qapi/qapi-visit-block-core.h" 45 #include "sysemu/block-backend.h" 46 #include "qemu/notify.h" 47 #include "qemu/option.h" 48 #include "qemu/coroutine.h" 49 #include "block/qapi.h" 50 #include "qemu/timer.h" 51 #include "qemu/cutils.h" 52 #include "qemu/id.h" 53 #include "qemu/range.h" 54 #include "qemu/rcu.h" 55 #include "block/coroutines.h" 56 57 #ifdef CONFIG_BSD 58 #include <sys/ioctl.h> 59 #include <sys/queue.h> 60 #if defined(HAVE_SYS_DISK_H) 61 #include <sys/disk.h> 62 #endif 63 #endif 64 65 #ifdef _WIN32 66 #include <windows.h> 67 #endif 68 69 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */ 70 71 /* Protected by BQL */ 72 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states = 73 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states); 74 75 /* Protected by BQL */ 76 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states = 77 QTAILQ_HEAD_INITIALIZER(all_bdrv_states); 78 79 /* Protected by BQL */ 80 static QLIST_HEAD(, BlockDriver) bdrv_drivers = 81 QLIST_HEAD_INITIALIZER(bdrv_drivers); 82 83 static BlockDriverState *bdrv_open_inherit(const char *filename, 84 const char *reference, 85 QDict *options, int flags, 86 BlockDriverState *parent, 87 const BdrvChildClass *child_class, 88 BdrvChildRole child_role, 89 Error **errp); 90 91 static bool bdrv_recurse_has_child(BlockDriverState *bs, 92 BlockDriverState *child); 93 94 static void GRAPH_WRLOCK 95 bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs); 96 97 static void GRAPH_WRLOCK 98 bdrv_remove_child(BdrvChild *child, Transaction *tran); 99 100 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, 101 BlockReopenQueue *queue, 102 Transaction *change_child_tran, Error **errp); 103 static void bdrv_reopen_commit(BDRVReopenState *reopen_state); 104 static void bdrv_reopen_abort(BDRVReopenState *reopen_state); 105 106 static bool bdrv_backing_overridden(BlockDriverState *bs); 107 108 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx, 109 GHashTable *visited, Transaction *tran, 110 Error **errp); 111 112 /* If non-zero, use only whitelisted block drivers */ 113 static int use_bdrv_whitelist; 114 115 #ifdef _WIN32 116 static int is_windows_drive_prefix(const char *filename) 117 { 118 return (((filename[0] >= 'a' && filename[0] <= 'z') || 119 (filename[0] >= 'A' && filename[0] <= 'Z')) && 120 filename[1] == ':'); 121 } 122 123 int is_windows_drive(const char *filename) 124 { 125 if (is_windows_drive_prefix(filename) && 126 filename[2] == '\0') 127 return 1; 128 if (strstart(filename, "\\\\.\\", NULL) || 129 strstart(filename, "//./", NULL)) 130 return 1; 131 return 0; 132 } 133 #endif 134 135 size_t bdrv_opt_mem_align(BlockDriverState *bs) 136 { 137 if (!bs || !bs->drv) { 138 /* page size or 4k (hdd sector size) should be on the safe side */ 139 return MAX(4096, qemu_real_host_page_size()); 140 } 141 IO_CODE(); 142 143 return bs->bl.opt_mem_alignment; 144 } 145 146 size_t bdrv_min_mem_align(BlockDriverState *bs) 147 { 148 if (!bs || !bs->drv) { 149 /* page size or 4k (hdd sector size) should be on the safe side */ 150 return MAX(4096, qemu_real_host_page_size()); 151 } 152 IO_CODE(); 153 154 return bs->bl.min_mem_alignment; 155 } 156 157 /* check if the path starts with "<protocol>:" */ 158 int path_has_protocol(const char *path) 159 { 160 const char *p; 161 162 #ifdef _WIN32 163 if (is_windows_drive(path) || 164 is_windows_drive_prefix(path)) { 165 return 0; 166 } 167 p = path + strcspn(path, ":/\\"); 168 #else 169 p = path + strcspn(path, ":/"); 170 #endif 171 172 return *p == ':'; 173 } 174 175 int path_is_absolute(const char *path) 176 { 177 #ifdef _WIN32 178 /* specific case for names like: "\\.\d:" */ 179 if (is_windows_drive(path) || is_windows_drive_prefix(path)) { 180 return 1; 181 } 182 return (*path == '/' || *path == '\\'); 183 #else 184 return (*path == '/'); 185 #endif 186 } 187 188 /* if filename is absolute, just return its duplicate. Otherwise, build a 189 path to it by considering it is relative to base_path. URL are 190 supported. */ 191 char *path_combine(const char *base_path, const char *filename) 192 { 193 const char *protocol_stripped = NULL; 194 const char *p, *p1; 195 char *result; 196 int len; 197 198 if (path_is_absolute(filename)) { 199 return g_strdup(filename); 200 } 201 202 if (path_has_protocol(base_path)) { 203 protocol_stripped = strchr(base_path, ':'); 204 if (protocol_stripped) { 205 protocol_stripped++; 206 } 207 } 208 p = protocol_stripped ?: base_path; 209 210 p1 = strrchr(base_path, '/'); 211 #ifdef _WIN32 212 { 213 const char *p2; 214 p2 = strrchr(base_path, '\\'); 215 if (!p1 || p2 > p1) { 216 p1 = p2; 217 } 218 } 219 #endif 220 if (p1) { 221 p1++; 222 } else { 223 p1 = base_path; 224 } 225 if (p1 > p) { 226 p = p1; 227 } 228 len = p - base_path; 229 230 result = g_malloc(len + strlen(filename) + 1); 231 memcpy(result, base_path, len); 232 strcpy(result + len, filename); 233 234 return result; 235 } 236 237 /* 238 * Helper function for bdrv_parse_filename() implementations to remove optional 239 * protocol prefixes (especially "file:") from a filename and for putting the 240 * stripped filename into the options QDict if there is such a prefix. 241 */ 242 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, 243 QDict *options) 244 { 245 if (strstart(filename, prefix, &filename)) { 246 /* Stripping the explicit protocol prefix may result in a protocol 247 * prefix being (wrongly) detected (if the filename contains a colon) */ 248 if (path_has_protocol(filename)) { 249 GString *fat_filename; 250 251 /* This means there is some colon before the first slash; therefore, 252 * this cannot be an absolute path */ 253 assert(!path_is_absolute(filename)); 254 255 /* And we can thus fix the protocol detection issue by prefixing it 256 * by "./" */ 257 fat_filename = g_string_new("./"); 258 g_string_append(fat_filename, filename); 259 260 assert(!path_has_protocol(fat_filename->str)); 261 262 qdict_put(options, "filename", 263 qstring_from_gstring(fat_filename)); 264 } else { 265 /* If no protocol prefix was detected, we can use the shortened 266 * filename as-is */ 267 qdict_put_str(options, "filename", filename); 268 } 269 } 270 } 271 272 273 /* Returns whether the image file is opened as read-only. Note that this can 274 * return false and writing to the image file is still not possible because the 275 * image is inactivated. */ 276 bool bdrv_is_read_only(BlockDriverState *bs) 277 { 278 IO_CODE(); 279 return !(bs->open_flags & BDRV_O_RDWR); 280 } 281 282 static int GRAPH_RDLOCK 283 bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, 284 bool ignore_allow_rdw, Error **errp) 285 { 286 IO_CODE(); 287 288 /* Do not set read_only if copy_on_read is enabled */ 289 if (bs->copy_on_read && read_only) { 290 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled", 291 bdrv_get_device_or_node_name(bs)); 292 return -EINVAL; 293 } 294 295 /* Do not clear read_only if it is prohibited */ 296 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) && 297 !ignore_allow_rdw) 298 { 299 error_setg(errp, "Node '%s' is read only", 300 bdrv_get_device_or_node_name(bs)); 301 return -EPERM; 302 } 303 304 return 0; 305 } 306 307 /* 308 * Called by a driver that can only provide a read-only image. 309 * 310 * Returns 0 if the node is already read-only or it could switch the node to 311 * read-only because BDRV_O_AUTO_RDONLY is set. 312 * 313 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set 314 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg 315 * is not NULL, it is used as the error message for the Error object. 316 */ 317 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg, 318 Error **errp) 319 { 320 int ret = 0; 321 IO_CODE(); 322 323 if (!(bs->open_flags & BDRV_O_RDWR)) { 324 return 0; 325 } 326 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) { 327 goto fail; 328 } 329 330 ret = bdrv_can_set_read_only(bs, true, false, NULL); 331 if (ret < 0) { 332 goto fail; 333 } 334 335 bs->open_flags &= ~BDRV_O_RDWR; 336 337 return 0; 338 339 fail: 340 error_setg(errp, "%s", errmsg ?: "Image is read-only"); 341 return -EACCES; 342 } 343 344 /* 345 * If @backing is empty, this function returns NULL without setting 346 * @errp. In all other cases, NULL will only be returned with @errp 347 * set. 348 * 349 * Therefore, a return value of NULL without @errp set means that 350 * there is no backing file; if @errp is set, there is one but its 351 * absolute filename cannot be generated. 352 */ 353 char *bdrv_get_full_backing_filename_from_filename(const char *backed, 354 const char *backing, 355 Error **errp) 356 { 357 if (backing[0] == '\0') { 358 return NULL; 359 } else if (path_has_protocol(backing) || path_is_absolute(backing)) { 360 return g_strdup(backing); 361 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) { 362 error_setg(errp, "Cannot use relative backing file names for '%s'", 363 backed); 364 return NULL; 365 } else { 366 return path_combine(backed, backing); 367 } 368 } 369 370 /* 371 * If @filename is empty or NULL, this function returns NULL without 372 * setting @errp. In all other cases, NULL will only be returned with 373 * @errp set. 374 */ 375 static char * GRAPH_RDLOCK 376 bdrv_make_absolute_filename(BlockDriverState *relative_to, 377 const char *filename, Error **errp) 378 { 379 char *dir, *full_name; 380 381 if (!filename || filename[0] == '\0') { 382 return NULL; 383 } else if (path_has_protocol(filename) || path_is_absolute(filename)) { 384 return g_strdup(filename); 385 } 386 387 dir = bdrv_dirname(relative_to, errp); 388 if (!dir) { 389 return NULL; 390 } 391 392 full_name = g_strconcat(dir, filename, NULL); 393 g_free(dir); 394 return full_name; 395 } 396 397 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp) 398 { 399 GLOBAL_STATE_CODE(); 400 return bdrv_make_absolute_filename(bs, bs->backing_file, errp); 401 } 402 403 void bdrv_register(BlockDriver *bdrv) 404 { 405 assert(bdrv->format_name); 406 GLOBAL_STATE_CODE(); 407 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list); 408 } 409 410 BlockDriverState *bdrv_new(void) 411 { 412 BlockDriverState *bs; 413 int i; 414 415 GLOBAL_STATE_CODE(); 416 417 bs = g_new0(BlockDriverState, 1); 418 QLIST_INIT(&bs->dirty_bitmaps); 419 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 420 QLIST_INIT(&bs->op_blockers[i]); 421 } 422 qemu_mutex_init(&bs->reqs_lock); 423 qemu_mutex_init(&bs->dirty_bitmap_mutex); 424 bs->refcnt = 1; 425 bs->aio_context = qemu_get_aio_context(); 426 427 qemu_co_queue_init(&bs->flush_queue); 428 429 qemu_co_mutex_init(&bs->bsc_modify_lock); 430 bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1); 431 432 for (i = 0; i < bdrv_drain_all_count; i++) { 433 bdrv_drained_begin(bs); 434 } 435 436 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list); 437 438 return bs; 439 } 440 441 static BlockDriver *bdrv_do_find_format(const char *format_name) 442 { 443 BlockDriver *drv1; 444 GLOBAL_STATE_CODE(); 445 446 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 447 if (!strcmp(drv1->format_name, format_name)) { 448 return drv1; 449 } 450 } 451 452 return NULL; 453 } 454 455 BlockDriver *bdrv_find_format(const char *format_name) 456 { 457 BlockDriver *drv1; 458 int i; 459 460 GLOBAL_STATE_CODE(); 461 462 drv1 = bdrv_do_find_format(format_name); 463 if (drv1) { 464 return drv1; 465 } 466 467 /* The driver isn't registered, maybe we need to load a module */ 468 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 469 if (!strcmp(block_driver_modules[i].format_name, format_name)) { 470 Error *local_err = NULL; 471 int rv = block_module_load(block_driver_modules[i].library_name, 472 &local_err); 473 if (rv > 0) { 474 return bdrv_do_find_format(format_name); 475 } else if (rv < 0) { 476 error_report_err(local_err); 477 } 478 break; 479 } 480 } 481 return NULL; 482 } 483 484 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only) 485 { 486 static const char *whitelist_rw[] = { 487 CONFIG_BDRV_RW_WHITELIST 488 NULL 489 }; 490 static const char *whitelist_ro[] = { 491 CONFIG_BDRV_RO_WHITELIST 492 NULL 493 }; 494 const char **p; 495 496 if (!whitelist_rw[0] && !whitelist_ro[0]) { 497 return 1; /* no whitelist, anything goes */ 498 } 499 500 for (p = whitelist_rw; *p; p++) { 501 if (!strcmp(format_name, *p)) { 502 return 1; 503 } 504 } 505 if (read_only) { 506 for (p = whitelist_ro; *p; p++) { 507 if (!strcmp(format_name, *p)) { 508 return 1; 509 } 510 } 511 } 512 return 0; 513 } 514 515 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only) 516 { 517 GLOBAL_STATE_CODE(); 518 return bdrv_format_is_whitelisted(drv->format_name, read_only); 519 } 520 521 bool bdrv_uses_whitelist(void) 522 { 523 return use_bdrv_whitelist; 524 } 525 526 typedef struct CreateCo { 527 BlockDriver *drv; 528 char *filename; 529 QemuOpts *opts; 530 int ret; 531 Error *err; 532 } CreateCo; 533 534 int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename, 535 QemuOpts *opts, Error **errp) 536 { 537 int ret; 538 GLOBAL_STATE_CODE(); 539 ERRP_GUARD(); 540 541 if (!drv->bdrv_co_create_opts) { 542 error_setg(errp, "Driver '%s' does not support image creation", 543 drv->format_name); 544 return -ENOTSUP; 545 } 546 547 ret = drv->bdrv_co_create_opts(drv, filename, opts, errp); 548 if (ret < 0 && !*errp) { 549 error_setg_errno(errp, -ret, "Could not create image"); 550 } 551 552 return ret; 553 } 554 555 /** 556 * Helper function for bdrv_create_file_fallback(): Resize @blk to at 557 * least the given @minimum_size. 558 * 559 * On success, return @blk's actual length. 560 * Otherwise, return -errno. 561 */ 562 static int64_t coroutine_fn GRAPH_UNLOCKED 563 create_file_fallback_truncate(BlockBackend *blk, int64_t minimum_size, 564 Error **errp) 565 { 566 Error *local_err = NULL; 567 int64_t size; 568 int ret; 569 570 GLOBAL_STATE_CODE(); 571 572 ret = blk_co_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0, 573 &local_err); 574 if (ret < 0 && ret != -ENOTSUP) { 575 error_propagate(errp, local_err); 576 return ret; 577 } 578 579 size = blk_co_getlength(blk); 580 if (size < 0) { 581 error_free(local_err); 582 error_setg_errno(errp, -size, 583 "Failed to inquire the new image file's length"); 584 return size; 585 } 586 587 if (size < minimum_size) { 588 /* Need to grow the image, but we failed to do that */ 589 error_propagate(errp, local_err); 590 return -ENOTSUP; 591 } 592 593 error_free(local_err); 594 local_err = NULL; 595 596 return size; 597 } 598 599 /** 600 * Helper function for bdrv_create_file_fallback(): Zero the first 601 * sector to remove any potentially pre-existing image header. 602 */ 603 static int coroutine_fn 604 create_file_fallback_zero_first_sector(BlockBackend *blk, 605 int64_t current_size, 606 Error **errp) 607 { 608 int64_t bytes_to_clear; 609 int ret; 610 611 GLOBAL_STATE_CODE(); 612 613 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE); 614 if (bytes_to_clear) { 615 ret = blk_co_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP); 616 if (ret < 0) { 617 error_setg_errno(errp, -ret, 618 "Failed to clear the new image's first sector"); 619 return ret; 620 } 621 } 622 623 return 0; 624 } 625 626 /** 627 * Simple implementation of bdrv_co_create_opts for protocol drivers 628 * which only support creation via opening a file 629 * (usually existing raw storage device) 630 */ 631 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv, 632 const char *filename, 633 QemuOpts *opts, 634 Error **errp) 635 { 636 BlockBackend *blk; 637 QDict *options; 638 int64_t size = 0; 639 char *buf = NULL; 640 PreallocMode prealloc; 641 Error *local_err = NULL; 642 int ret; 643 644 GLOBAL_STATE_CODE(); 645 646 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0); 647 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC); 648 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf, 649 PREALLOC_MODE_OFF, &local_err); 650 g_free(buf); 651 if (local_err) { 652 error_propagate(errp, local_err); 653 return -EINVAL; 654 } 655 656 if (prealloc != PREALLOC_MODE_OFF) { 657 error_setg(errp, "Unsupported preallocation mode '%s'", 658 PreallocMode_str(prealloc)); 659 return -ENOTSUP; 660 } 661 662 options = qdict_new(); 663 qdict_put_str(options, "driver", drv->format_name); 664 665 blk = blk_co_new_open(filename, NULL, options, 666 BDRV_O_RDWR | BDRV_O_RESIZE, errp); 667 if (!blk) { 668 error_prepend(errp, "Protocol driver '%s' does not support creating " 669 "new images, so an existing image must be selected as " 670 "the target; however, opening the given target as an " 671 "existing image failed: ", 672 drv->format_name); 673 return -EINVAL; 674 } 675 676 size = create_file_fallback_truncate(blk, size, errp); 677 if (size < 0) { 678 ret = size; 679 goto out; 680 } 681 682 ret = create_file_fallback_zero_first_sector(blk, size, errp); 683 if (ret < 0) { 684 goto out; 685 } 686 687 ret = 0; 688 out: 689 blk_co_unref(blk); 690 return ret; 691 } 692 693 int coroutine_fn bdrv_co_create_file(const char *filename, QemuOpts *opts, 694 Error **errp) 695 { 696 QemuOpts *protocol_opts; 697 BlockDriver *drv; 698 QDict *qdict; 699 int ret; 700 701 GLOBAL_STATE_CODE(); 702 703 drv = bdrv_find_protocol(filename, true, errp); 704 if (drv == NULL) { 705 return -ENOENT; 706 } 707 708 if (!drv->create_opts) { 709 error_setg(errp, "Driver '%s' does not support image creation", 710 drv->format_name); 711 return -ENOTSUP; 712 } 713 714 /* 715 * 'opts' contains a QemuOptsList with a combination of format and protocol 716 * default values. 717 * 718 * The format properly removes its options, but the default values remain 719 * in 'opts->list'. So if the protocol has options with the same name 720 * (e.g. rbd has 'cluster_size' as qcow2), it will see the default values 721 * of the format, since for overlapping options, the format wins. 722 * 723 * To avoid this issue, lets convert QemuOpts to QDict, in this way we take 724 * only the set options, and then convert it back to QemuOpts, using the 725 * create_opts of the protocol. So the new QemuOpts, will contain only the 726 * protocol defaults. 727 */ 728 qdict = qemu_opts_to_qdict(opts, NULL); 729 protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp); 730 if (protocol_opts == NULL) { 731 ret = -EINVAL; 732 goto out; 733 } 734 735 ret = bdrv_co_create(drv, filename, protocol_opts, errp); 736 out: 737 qemu_opts_del(protocol_opts); 738 qobject_unref(qdict); 739 return ret; 740 } 741 742 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp) 743 { 744 Error *local_err = NULL; 745 int ret; 746 747 IO_CODE(); 748 assert(bs != NULL); 749 assert_bdrv_graph_readable(); 750 751 if (!bs->drv) { 752 error_setg(errp, "Block node '%s' is not opened", bs->filename); 753 return -ENOMEDIUM; 754 } 755 756 if (!bs->drv->bdrv_co_delete_file) { 757 error_setg(errp, "Driver '%s' does not support image deletion", 758 bs->drv->format_name); 759 return -ENOTSUP; 760 } 761 762 ret = bs->drv->bdrv_co_delete_file(bs, &local_err); 763 if (ret < 0) { 764 error_propagate(errp, local_err); 765 } 766 767 return ret; 768 } 769 770 void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs) 771 { 772 Error *local_err = NULL; 773 int ret; 774 IO_CODE(); 775 776 if (!bs) { 777 return; 778 } 779 780 ret = bdrv_co_delete_file(bs, &local_err); 781 /* 782 * ENOTSUP will happen if the block driver doesn't support 783 * the 'bdrv_co_delete_file' interface. This is a predictable 784 * scenario and shouldn't be reported back to the user. 785 */ 786 if (ret == -ENOTSUP) { 787 error_free(local_err); 788 } else if (ret < 0) { 789 error_report_err(local_err); 790 } 791 } 792 793 /** 794 * Try to get @bs's logical and physical block size. 795 * On success, store them in @bsz struct and return 0. 796 * On failure return -errno. 797 * @bs must not be empty. 798 */ 799 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz) 800 { 801 BlockDriver *drv = bs->drv; 802 BlockDriverState *filtered = bdrv_filter_bs(bs); 803 GLOBAL_STATE_CODE(); 804 805 if (drv && drv->bdrv_probe_blocksizes) { 806 return drv->bdrv_probe_blocksizes(bs, bsz); 807 } else if (filtered) { 808 return bdrv_probe_blocksizes(filtered, bsz); 809 } 810 811 return -ENOTSUP; 812 } 813 814 /** 815 * Try to get @bs's geometry (cyls, heads, sectors). 816 * On success, store them in @geo struct and return 0. 817 * On failure return -errno. 818 * @bs must not be empty. 819 */ 820 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo) 821 { 822 BlockDriver *drv = bs->drv; 823 BlockDriverState *filtered; 824 825 GLOBAL_STATE_CODE(); 826 GRAPH_RDLOCK_GUARD_MAINLOOP(); 827 828 if (drv && drv->bdrv_probe_geometry) { 829 return drv->bdrv_probe_geometry(bs, geo); 830 } 831 832 filtered = bdrv_filter_bs(bs); 833 if (filtered) { 834 return bdrv_probe_geometry(filtered, geo); 835 } 836 837 return -ENOTSUP; 838 } 839 840 /* 841 * Create a uniquely-named empty temporary file. 842 * Return the actual file name used upon success, otherwise NULL. 843 * This string should be freed with g_free() when not needed any longer. 844 * 845 * Note: creating a temporary file for the caller to (re)open is 846 * inherently racy. Use g_file_open_tmp() instead whenever practical. 847 */ 848 char *create_tmp_file(Error **errp) 849 { 850 int fd; 851 const char *tmpdir; 852 g_autofree char *filename = NULL; 853 854 tmpdir = g_get_tmp_dir(); 855 #ifndef _WIN32 856 /* 857 * See commit 69bef79 ("block: use /var/tmp instead of /tmp for -snapshot") 858 * 859 * This function is used to create temporary disk images (like -snapshot), 860 * so the files can become very large. /tmp is often a tmpfs where as 861 * /var/tmp is usually on a disk, so more appropriate for disk images. 862 */ 863 if (!g_strcmp0(tmpdir, "/tmp")) { 864 tmpdir = "/var/tmp"; 865 } 866 #endif 867 868 filename = g_strdup_printf("%s/vl.XXXXXX", tmpdir); 869 fd = g_mkstemp(filename); 870 if (fd < 0) { 871 error_setg_errno(errp, errno, "Could not open temporary file '%s'", 872 filename); 873 return NULL; 874 } 875 close(fd); 876 877 return g_steal_pointer(&filename); 878 } 879 880 /* 881 * Detect host devices. By convention, /dev/cdrom[N] is always 882 * recognized as a host CDROM. 883 */ 884 static BlockDriver *find_hdev_driver(const char *filename) 885 { 886 int score_max = 0, score; 887 BlockDriver *drv = NULL, *d; 888 GLOBAL_STATE_CODE(); 889 890 QLIST_FOREACH(d, &bdrv_drivers, list) { 891 if (d->bdrv_probe_device) { 892 score = d->bdrv_probe_device(filename); 893 if (score > score_max) { 894 score_max = score; 895 drv = d; 896 } 897 } 898 } 899 900 return drv; 901 } 902 903 static BlockDriver *bdrv_do_find_protocol(const char *protocol) 904 { 905 BlockDriver *drv1; 906 GLOBAL_STATE_CODE(); 907 908 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 909 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) { 910 return drv1; 911 } 912 } 913 914 return NULL; 915 } 916 917 BlockDriver *bdrv_find_protocol(const char *filename, 918 bool allow_protocol_prefix, 919 Error **errp) 920 { 921 BlockDriver *drv1; 922 char protocol[128]; 923 int len; 924 const char *p; 925 int i; 926 927 GLOBAL_STATE_CODE(); 928 /* TODO Drivers without bdrv_file_open must be specified explicitly */ 929 930 /* 931 * XXX(hch): we really should not let host device detection 932 * override an explicit protocol specification, but moving this 933 * later breaks access to device names with colons in them. 934 * Thanks to the brain-dead persistent naming schemes on udev- 935 * based Linux systems those actually are quite common. 936 */ 937 drv1 = find_hdev_driver(filename); 938 if (drv1) { 939 return drv1; 940 } 941 942 if (!path_has_protocol(filename) || !allow_protocol_prefix) { 943 return &bdrv_file; 944 } 945 946 p = strchr(filename, ':'); 947 assert(p != NULL); 948 len = p - filename; 949 if (len > sizeof(protocol) - 1) 950 len = sizeof(protocol) - 1; 951 memcpy(protocol, filename, len); 952 protocol[len] = '\0'; 953 954 drv1 = bdrv_do_find_protocol(protocol); 955 if (drv1) { 956 return drv1; 957 } 958 959 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 960 if (block_driver_modules[i].protocol_name && 961 !strcmp(block_driver_modules[i].protocol_name, protocol)) { 962 int rv = block_module_load(block_driver_modules[i].library_name, errp); 963 if (rv > 0) { 964 drv1 = bdrv_do_find_protocol(protocol); 965 } else if (rv < 0) { 966 return NULL; 967 } 968 break; 969 } 970 } 971 972 if (!drv1) { 973 error_setg(errp, "Unknown protocol '%s'", protocol); 974 } 975 return drv1; 976 } 977 978 /* 979 * Guess image format by probing its contents. 980 * This is not a good idea when your image is raw (CVE-2008-2004), but 981 * we do it anyway for backward compatibility. 982 * 983 * @buf contains the image's first @buf_size bytes. 984 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE, 985 * but can be smaller if the image file is smaller) 986 * @filename is its filename. 987 * 988 * For all block drivers, call the bdrv_probe() method to get its 989 * probing score. 990 * Return the first block driver with the highest probing score. 991 */ 992 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size, 993 const char *filename) 994 { 995 int score_max = 0, score; 996 BlockDriver *drv = NULL, *d; 997 IO_CODE(); 998 999 QLIST_FOREACH(d, &bdrv_drivers, list) { 1000 if (d->bdrv_probe) { 1001 score = d->bdrv_probe(buf, buf_size, filename); 1002 if (score > score_max) { 1003 score_max = score; 1004 drv = d; 1005 } 1006 } 1007 } 1008 1009 return drv; 1010 } 1011 1012 static int find_image_format(BlockBackend *file, const char *filename, 1013 BlockDriver **pdrv, Error **errp) 1014 { 1015 BlockDriver *drv; 1016 uint8_t buf[BLOCK_PROBE_BUF_SIZE]; 1017 int ret = 0; 1018 1019 GLOBAL_STATE_CODE(); 1020 1021 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */ 1022 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) { 1023 *pdrv = &bdrv_raw; 1024 return ret; 1025 } 1026 1027 ret = blk_pread(file, 0, sizeof(buf), buf, 0); 1028 if (ret < 0) { 1029 error_setg_errno(errp, -ret, "Could not read image for determining its " 1030 "format"); 1031 *pdrv = NULL; 1032 return ret; 1033 } 1034 1035 drv = bdrv_probe_all(buf, sizeof(buf), filename); 1036 if (!drv) { 1037 error_setg(errp, "Could not determine image format: No compatible " 1038 "driver found"); 1039 *pdrv = NULL; 1040 return -ENOENT; 1041 } 1042 1043 *pdrv = drv; 1044 return 0; 1045 } 1046 1047 /** 1048 * Set the current 'total_sectors' value 1049 * Return 0 on success, -errno on error. 1050 */ 1051 int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs, 1052 int64_t hint) 1053 { 1054 BlockDriver *drv = bs->drv; 1055 IO_CODE(); 1056 assert_bdrv_graph_readable(); 1057 1058 if (!drv) { 1059 return -ENOMEDIUM; 1060 } 1061 1062 /* Do not attempt drv->bdrv_co_getlength() on scsi-generic devices */ 1063 if (bdrv_is_sg(bs)) 1064 return 0; 1065 1066 /* query actual device if possible, otherwise just trust the hint */ 1067 if (drv->bdrv_co_getlength) { 1068 int64_t length = drv->bdrv_co_getlength(bs); 1069 if (length < 0) { 1070 return length; 1071 } 1072 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE); 1073 } 1074 1075 bs->total_sectors = hint; 1076 1077 if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) { 1078 return -EFBIG; 1079 } 1080 1081 return 0; 1082 } 1083 1084 /** 1085 * Combines a QDict of new block driver @options with any missing options taken 1086 * from @old_options, so that leaving out an option defaults to its old value. 1087 */ 1088 static void bdrv_join_options(BlockDriverState *bs, QDict *options, 1089 QDict *old_options) 1090 { 1091 GLOBAL_STATE_CODE(); 1092 if (bs->drv && bs->drv->bdrv_join_options) { 1093 bs->drv->bdrv_join_options(options, old_options); 1094 } else { 1095 qdict_join(options, old_options, false); 1096 } 1097 } 1098 1099 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts, 1100 int open_flags, 1101 Error **errp) 1102 { 1103 Error *local_err = NULL; 1104 char *value = qemu_opt_get_del(opts, "detect-zeroes"); 1105 BlockdevDetectZeroesOptions detect_zeroes = 1106 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value, 1107 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err); 1108 GLOBAL_STATE_CODE(); 1109 g_free(value); 1110 if (local_err) { 1111 error_propagate(errp, local_err); 1112 return detect_zeroes; 1113 } 1114 1115 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP && 1116 !(open_flags & BDRV_O_UNMAP)) 1117 { 1118 error_setg(errp, "setting detect-zeroes to unmap is not allowed " 1119 "without setting discard operation to unmap"); 1120 } 1121 1122 return detect_zeroes; 1123 } 1124 1125 /** 1126 * Set open flags for aio engine 1127 * 1128 * Return 0 on success, -1 if the engine specified is invalid 1129 */ 1130 int bdrv_parse_aio(const char *mode, int *flags) 1131 { 1132 if (!strcmp(mode, "threads")) { 1133 /* do nothing, default */ 1134 } else if (!strcmp(mode, "native")) { 1135 *flags |= BDRV_O_NATIVE_AIO; 1136 #ifdef CONFIG_LINUX_IO_URING 1137 } else if (!strcmp(mode, "io_uring")) { 1138 *flags |= BDRV_O_IO_URING; 1139 #endif 1140 } else { 1141 return -1; 1142 } 1143 1144 return 0; 1145 } 1146 1147 /** 1148 * Set open flags for a given discard mode 1149 * 1150 * Return 0 on success, -1 if the discard mode was invalid. 1151 */ 1152 int bdrv_parse_discard_flags(const char *mode, int *flags) 1153 { 1154 *flags &= ~BDRV_O_UNMAP; 1155 1156 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) { 1157 /* do nothing */ 1158 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) { 1159 *flags |= BDRV_O_UNMAP; 1160 } else { 1161 return -1; 1162 } 1163 1164 return 0; 1165 } 1166 1167 /** 1168 * Set open flags for a given cache mode 1169 * 1170 * Return 0 on success, -1 if the cache mode was invalid. 1171 */ 1172 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough) 1173 { 1174 *flags &= ~BDRV_O_CACHE_MASK; 1175 1176 if (!strcmp(mode, "off") || !strcmp(mode, "none")) { 1177 *writethrough = false; 1178 *flags |= BDRV_O_NOCACHE; 1179 } else if (!strcmp(mode, "directsync")) { 1180 *writethrough = true; 1181 *flags |= BDRV_O_NOCACHE; 1182 } else if (!strcmp(mode, "writeback")) { 1183 *writethrough = false; 1184 } else if (!strcmp(mode, "unsafe")) { 1185 *writethrough = false; 1186 *flags |= BDRV_O_NO_FLUSH; 1187 } else if (!strcmp(mode, "writethrough")) { 1188 *writethrough = true; 1189 } else { 1190 return -1; 1191 } 1192 1193 return 0; 1194 } 1195 1196 static char *bdrv_child_get_parent_desc(BdrvChild *c) 1197 { 1198 BlockDriverState *parent = c->opaque; 1199 return g_strdup_printf("node '%s'", bdrv_get_node_name(parent)); 1200 } 1201 1202 static void GRAPH_RDLOCK bdrv_child_cb_drained_begin(BdrvChild *child) 1203 { 1204 BlockDriverState *bs = child->opaque; 1205 bdrv_do_drained_begin_quiesce(bs, NULL); 1206 } 1207 1208 static bool GRAPH_RDLOCK bdrv_child_cb_drained_poll(BdrvChild *child) 1209 { 1210 BlockDriverState *bs = child->opaque; 1211 return bdrv_drain_poll(bs, NULL, false); 1212 } 1213 1214 static void GRAPH_RDLOCK bdrv_child_cb_drained_end(BdrvChild *child) 1215 { 1216 BlockDriverState *bs = child->opaque; 1217 bdrv_drained_end(bs); 1218 } 1219 1220 static int bdrv_child_cb_inactivate(BdrvChild *child) 1221 { 1222 BlockDriverState *bs = child->opaque; 1223 GLOBAL_STATE_CODE(); 1224 assert(bs->open_flags & BDRV_O_INACTIVE); 1225 return 0; 1226 } 1227 1228 static bool bdrv_child_cb_change_aio_ctx(BdrvChild *child, AioContext *ctx, 1229 GHashTable *visited, Transaction *tran, 1230 Error **errp) 1231 { 1232 BlockDriverState *bs = child->opaque; 1233 return bdrv_change_aio_context(bs, ctx, visited, tran, errp); 1234 } 1235 1236 /* 1237 * Returns the options and flags that a temporary snapshot should get, based on 1238 * the originally requested flags (the originally requested image will have 1239 * flags like a backing file) 1240 */ 1241 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options, 1242 int parent_flags, QDict *parent_options) 1243 { 1244 GLOBAL_STATE_CODE(); 1245 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY; 1246 1247 /* For temporary files, unconditional cache=unsafe is fine */ 1248 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off"); 1249 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on"); 1250 1251 /* Copy the read-only and discard options from the parent */ 1252 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1253 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD); 1254 1255 /* aio=native doesn't work for cache.direct=off, so disable it for the 1256 * temporary snapshot */ 1257 *child_flags &= ~BDRV_O_NATIVE_AIO; 1258 } 1259 1260 static void GRAPH_WRLOCK bdrv_backing_attach(BdrvChild *c) 1261 { 1262 BlockDriverState *parent = c->opaque; 1263 BlockDriverState *backing_hd = c->bs; 1264 1265 GLOBAL_STATE_CODE(); 1266 assert(!parent->backing_blocker); 1267 error_setg(&parent->backing_blocker, 1268 "node is used as backing hd of '%s'", 1269 bdrv_get_device_or_node_name(parent)); 1270 1271 bdrv_refresh_filename(backing_hd); 1272 1273 parent->open_flags &= ~BDRV_O_NO_BACKING; 1274 1275 bdrv_op_block_all(backing_hd, parent->backing_blocker); 1276 /* Otherwise we won't be able to commit or stream */ 1277 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET, 1278 parent->backing_blocker); 1279 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM, 1280 parent->backing_blocker); 1281 /* 1282 * We do backup in 3 ways: 1283 * 1. drive backup 1284 * The target bs is new opened, and the source is top BDS 1285 * 2. blockdev backup 1286 * Both the source and the target are top BDSes. 1287 * 3. internal backup(used for block replication) 1288 * Both the source and the target are backing file 1289 * 1290 * In case 1 and 2, neither the source nor the target is the backing file. 1291 * In case 3, we will block the top BDS, so there is only one block job 1292 * for the top BDS and its backing chain. 1293 */ 1294 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE, 1295 parent->backing_blocker); 1296 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET, 1297 parent->backing_blocker); 1298 } 1299 1300 static void bdrv_backing_detach(BdrvChild *c) 1301 { 1302 BlockDriverState *parent = c->opaque; 1303 1304 GLOBAL_STATE_CODE(); 1305 assert(parent->backing_blocker); 1306 bdrv_op_unblock_all(c->bs, parent->backing_blocker); 1307 error_free(parent->backing_blocker); 1308 parent->backing_blocker = NULL; 1309 } 1310 1311 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base, 1312 const char *filename, Error **errp) 1313 { 1314 BlockDriverState *parent = c->opaque; 1315 bool read_only = bdrv_is_read_only(parent); 1316 int ret; 1317 GLOBAL_STATE_CODE(); 1318 1319 if (read_only) { 1320 ret = bdrv_reopen_set_read_only(parent, false, errp); 1321 if (ret < 0) { 1322 return ret; 1323 } 1324 } 1325 1326 ret = bdrv_change_backing_file(parent, filename, 1327 base->drv ? base->drv->format_name : "", 1328 false); 1329 if (ret < 0) { 1330 error_setg_errno(errp, -ret, "Could not update backing file link"); 1331 } 1332 1333 if (read_only) { 1334 bdrv_reopen_set_read_only(parent, true, NULL); 1335 } 1336 1337 return ret; 1338 } 1339 1340 /* 1341 * Returns the options and flags that a generic child of a BDS should 1342 * get, based on the given options and flags for the parent BDS. 1343 */ 1344 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format, 1345 int *child_flags, QDict *child_options, 1346 int parent_flags, QDict *parent_options) 1347 { 1348 int flags = parent_flags; 1349 GLOBAL_STATE_CODE(); 1350 1351 /* 1352 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL. 1353 * Generally, the question to answer is: Should this child be 1354 * format-probed by default? 1355 */ 1356 1357 /* 1358 * Pure and non-filtered data children of non-format nodes should 1359 * be probed by default (even when the node itself has BDRV_O_PROTOCOL 1360 * set). This only affects a very limited set of drivers (namely 1361 * quorum and blkverify when this comment was written). 1362 * Force-clear BDRV_O_PROTOCOL then. 1363 */ 1364 if (!parent_is_format && 1365 (role & BDRV_CHILD_DATA) && 1366 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED))) 1367 { 1368 flags &= ~BDRV_O_PROTOCOL; 1369 } 1370 1371 /* 1372 * All children of format nodes (except for COW children) and all 1373 * metadata children in general should never be format-probed. 1374 * Force-set BDRV_O_PROTOCOL then. 1375 */ 1376 if ((parent_is_format && !(role & BDRV_CHILD_COW)) || 1377 (role & BDRV_CHILD_METADATA)) 1378 { 1379 flags |= BDRV_O_PROTOCOL; 1380 } 1381 1382 /* 1383 * If the cache mode isn't explicitly set, inherit direct and no-flush from 1384 * the parent. 1385 */ 1386 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT); 1387 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH); 1388 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE); 1389 1390 if (role & BDRV_CHILD_COW) { 1391 /* backing files are opened read-only by default */ 1392 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on"); 1393 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off"); 1394 } else { 1395 /* Inherit the read-only option from the parent if it's not set */ 1396 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1397 qdict_copy_default(child_options, parent_options, 1398 BDRV_OPT_AUTO_READ_ONLY); 1399 } 1400 1401 /* 1402 * bdrv_co_pdiscard() respects unmap policy for the parent, so we 1403 * can default to enable it on lower layers regardless of the 1404 * parent option. 1405 */ 1406 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap"); 1407 1408 /* Clear flags that only apply to the top layer */ 1409 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ); 1410 1411 if (role & BDRV_CHILD_METADATA) { 1412 flags &= ~BDRV_O_NO_IO; 1413 } 1414 if (role & BDRV_CHILD_COW) { 1415 flags &= ~BDRV_O_TEMPORARY; 1416 } 1417 1418 *child_flags = flags; 1419 } 1420 1421 static void GRAPH_WRLOCK bdrv_child_cb_attach(BdrvChild *child) 1422 { 1423 BlockDriverState *bs = child->opaque; 1424 1425 assert_bdrv_graph_writable(); 1426 QLIST_INSERT_HEAD(&bs->children, child, next); 1427 if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) { 1428 /* 1429 * Here we handle filters and block/raw-format.c when it behave like 1430 * filter. They generally have a single PRIMARY child, which is also the 1431 * FILTERED child, and that they may have multiple more children, which 1432 * are neither PRIMARY nor FILTERED. And never we have a COW child here. 1433 * So bs->file will be the PRIMARY child, unless the PRIMARY child goes 1434 * into bs->backing on exceptional cases; and bs->backing will be 1435 * nothing else. 1436 */ 1437 assert(!(child->role & BDRV_CHILD_COW)); 1438 if (child->role & BDRV_CHILD_PRIMARY) { 1439 assert(child->role & BDRV_CHILD_FILTERED); 1440 assert(!bs->backing); 1441 assert(!bs->file); 1442 1443 if (bs->drv->filtered_child_is_backing) { 1444 bs->backing = child; 1445 } else { 1446 bs->file = child; 1447 } 1448 } else { 1449 assert(!(child->role & BDRV_CHILD_FILTERED)); 1450 } 1451 } else if (child->role & BDRV_CHILD_COW) { 1452 assert(bs->drv->supports_backing); 1453 assert(!(child->role & BDRV_CHILD_PRIMARY)); 1454 assert(!bs->backing); 1455 bs->backing = child; 1456 bdrv_backing_attach(child); 1457 } else if (child->role & BDRV_CHILD_PRIMARY) { 1458 assert(!bs->file); 1459 bs->file = child; 1460 } 1461 } 1462 1463 static void GRAPH_WRLOCK bdrv_child_cb_detach(BdrvChild *child) 1464 { 1465 BlockDriverState *bs = child->opaque; 1466 1467 if (child->role & BDRV_CHILD_COW) { 1468 bdrv_backing_detach(child); 1469 } 1470 1471 assert_bdrv_graph_writable(); 1472 QLIST_REMOVE(child, next); 1473 if (child == bs->backing) { 1474 assert(child != bs->file); 1475 bs->backing = NULL; 1476 } else if (child == bs->file) { 1477 bs->file = NULL; 1478 } 1479 } 1480 1481 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base, 1482 const char *filename, Error **errp) 1483 { 1484 if (c->role & BDRV_CHILD_COW) { 1485 return bdrv_backing_update_filename(c, base, filename, errp); 1486 } 1487 return 0; 1488 } 1489 1490 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c) 1491 { 1492 BlockDriverState *bs = c->opaque; 1493 IO_CODE(); 1494 1495 return bdrv_get_aio_context(bs); 1496 } 1497 1498 const BdrvChildClass child_of_bds = { 1499 .parent_is_bds = true, 1500 .get_parent_desc = bdrv_child_get_parent_desc, 1501 .inherit_options = bdrv_inherited_options, 1502 .drained_begin = bdrv_child_cb_drained_begin, 1503 .drained_poll = bdrv_child_cb_drained_poll, 1504 .drained_end = bdrv_child_cb_drained_end, 1505 .attach = bdrv_child_cb_attach, 1506 .detach = bdrv_child_cb_detach, 1507 .inactivate = bdrv_child_cb_inactivate, 1508 .change_aio_ctx = bdrv_child_cb_change_aio_ctx, 1509 .update_filename = bdrv_child_cb_update_filename, 1510 .get_parent_aio_context = child_of_bds_get_parent_aio_context, 1511 }; 1512 1513 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c) 1514 { 1515 IO_CODE(); 1516 return c->klass->get_parent_aio_context(c); 1517 } 1518 1519 static int bdrv_open_flags(BlockDriverState *bs, int flags) 1520 { 1521 int open_flags = flags; 1522 GLOBAL_STATE_CODE(); 1523 1524 /* 1525 * Clear flags that are internal to the block layer before opening the 1526 * image. 1527 */ 1528 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL); 1529 1530 return open_flags; 1531 } 1532 1533 static void update_flags_from_options(int *flags, QemuOpts *opts) 1534 { 1535 GLOBAL_STATE_CODE(); 1536 1537 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY); 1538 1539 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) { 1540 *flags |= BDRV_O_NO_FLUSH; 1541 } 1542 1543 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) { 1544 *flags |= BDRV_O_NOCACHE; 1545 } 1546 1547 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) { 1548 *flags |= BDRV_O_RDWR; 1549 } 1550 1551 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) { 1552 *flags |= BDRV_O_AUTO_RDONLY; 1553 } 1554 } 1555 1556 static void update_options_from_flags(QDict *options, int flags) 1557 { 1558 GLOBAL_STATE_CODE(); 1559 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) { 1560 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE); 1561 } 1562 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) { 1563 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH, 1564 flags & BDRV_O_NO_FLUSH); 1565 } 1566 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) { 1567 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR)); 1568 } 1569 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) { 1570 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY, 1571 flags & BDRV_O_AUTO_RDONLY); 1572 } 1573 } 1574 1575 static void bdrv_assign_node_name(BlockDriverState *bs, 1576 const char *node_name, 1577 Error **errp) 1578 { 1579 char *gen_node_name = NULL; 1580 GLOBAL_STATE_CODE(); 1581 1582 if (!node_name) { 1583 node_name = gen_node_name = id_generate(ID_BLOCK); 1584 } else if (!id_wellformed(node_name)) { 1585 /* 1586 * Check for empty string or invalid characters, but not if it is 1587 * generated (generated names use characters not available to the user) 1588 */ 1589 error_setg(errp, "Invalid node-name: '%s'", node_name); 1590 return; 1591 } 1592 1593 /* takes care of avoiding namespaces collisions */ 1594 if (blk_by_name(node_name)) { 1595 error_setg(errp, "node-name=%s is conflicting with a device id", 1596 node_name); 1597 goto out; 1598 } 1599 1600 /* takes care of avoiding duplicates node names */ 1601 if (bdrv_find_node(node_name)) { 1602 error_setg(errp, "Duplicate nodes with node-name='%s'", node_name); 1603 goto out; 1604 } 1605 1606 /* Make sure that the node name isn't truncated */ 1607 if (strlen(node_name) >= sizeof(bs->node_name)) { 1608 error_setg(errp, "Node name too long"); 1609 goto out; 1610 } 1611 1612 /* copy node name into the bs and insert it into the graph list */ 1613 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name); 1614 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list); 1615 out: 1616 g_free(gen_node_name); 1617 } 1618 1619 /* 1620 * The caller must always hold @bs AioContext lock, because this function calls 1621 * bdrv_refresh_total_sectors() which polls when called from non-coroutine 1622 * context. 1623 */ 1624 static int no_coroutine_fn GRAPH_UNLOCKED 1625 bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name, 1626 QDict *options, int open_flags, Error **errp) 1627 { 1628 Error *local_err = NULL; 1629 int i, ret; 1630 GLOBAL_STATE_CODE(); 1631 1632 bdrv_assign_node_name(bs, node_name, &local_err); 1633 if (local_err) { 1634 error_propagate(errp, local_err); 1635 return -EINVAL; 1636 } 1637 1638 bs->drv = drv; 1639 bs->opaque = g_malloc0(drv->instance_size); 1640 1641 if (drv->bdrv_file_open) { 1642 assert(!drv->bdrv_needs_filename || bs->filename[0]); 1643 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err); 1644 } else if (drv->bdrv_open) { 1645 ret = drv->bdrv_open(bs, options, open_flags, &local_err); 1646 } else { 1647 ret = 0; 1648 } 1649 1650 if (ret < 0) { 1651 if (local_err) { 1652 error_propagate(errp, local_err); 1653 } else if (bs->filename[0]) { 1654 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename); 1655 } else { 1656 error_setg_errno(errp, -ret, "Could not open image"); 1657 } 1658 goto open_failed; 1659 } 1660 1661 assert(!(bs->supported_read_flags & ~BDRV_REQ_MASK)); 1662 assert(!(bs->supported_write_flags & ~BDRV_REQ_MASK)); 1663 1664 /* 1665 * Always allow the BDRV_REQ_REGISTERED_BUF optimization hint. This saves 1666 * drivers that pass read/write requests through to a child the trouble of 1667 * declaring support explicitly. 1668 * 1669 * Drivers must not propagate this flag accidentally when they initiate I/O 1670 * to a bounce buffer. That case should be rare though. 1671 */ 1672 bs->supported_read_flags |= BDRV_REQ_REGISTERED_BUF; 1673 bs->supported_write_flags |= BDRV_REQ_REGISTERED_BUF; 1674 1675 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); 1676 if (ret < 0) { 1677 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 1678 return ret; 1679 } 1680 1681 bdrv_graph_rdlock_main_loop(); 1682 bdrv_refresh_limits(bs, NULL, &local_err); 1683 bdrv_graph_rdunlock_main_loop(); 1684 1685 if (local_err) { 1686 error_propagate(errp, local_err); 1687 return -EINVAL; 1688 } 1689 1690 assert(bdrv_opt_mem_align(bs) != 0); 1691 assert(bdrv_min_mem_align(bs) != 0); 1692 assert(is_power_of_2(bs->bl.request_alignment)); 1693 1694 for (i = 0; i < bs->quiesce_counter; i++) { 1695 if (drv->bdrv_drain_begin) { 1696 drv->bdrv_drain_begin(bs); 1697 } 1698 } 1699 1700 return 0; 1701 open_failed: 1702 bs->drv = NULL; 1703 1704 bdrv_graph_wrlock(); 1705 if (bs->file != NULL) { 1706 bdrv_unref_child(bs, bs->file); 1707 assert(!bs->file); 1708 } 1709 bdrv_graph_wrunlock(); 1710 1711 g_free(bs->opaque); 1712 bs->opaque = NULL; 1713 return ret; 1714 } 1715 1716 /* 1717 * Create and open a block node. 1718 * 1719 * @options is a QDict of options to pass to the block drivers, or NULL for an 1720 * empty set of options. The reference to the QDict belongs to the block layer 1721 * after the call (even on failure), so if the caller intends to reuse the 1722 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 1723 */ 1724 BlockDriverState *bdrv_new_open_driver_opts(BlockDriver *drv, 1725 const char *node_name, 1726 QDict *options, int flags, 1727 Error **errp) 1728 { 1729 BlockDriverState *bs; 1730 int ret; 1731 1732 GLOBAL_STATE_CODE(); 1733 1734 bs = bdrv_new(); 1735 bs->open_flags = flags; 1736 bs->options = options ?: qdict_new(); 1737 bs->explicit_options = qdict_clone_shallow(bs->options); 1738 bs->opaque = NULL; 1739 1740 update_options_from_flags(bs->options, flags); 1741 1742 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp); 1743 if (ret < 0) { 1744 qobject_unref(bs->explicit_options); 1745 bs->explicit_options = NULL; 1746 qobject_unref(bs->options); 1747 bs->options = NULL; 1748 bdrv_unref(bs); 1749 return NULL; 1750 } 1751 1752 return bs; 1753 } 1754 1755 /* Create and open a block node. */ 1756 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name, 1757 int flags, Error **errp) 1758 { 1759 GLOBAL_STATE_CODE(); 1760 return bdrv_new_open_driver_opts(drv, node_name, NULL, flags, errp); 1761 } 1762 1763 QemuOptsList bdrv_runtime_opts = { 1764 .name = "bdrv_common", 1765 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head), 1766 .desc = { 1767 { 1768 .name = "node-name", 1769 .type = QEMU_OPT_STRING, 1770 .help = "Node name of the block device node", 1771 }, 1772 { 1773 .name = "driver", 1774 .type = QEMU_OPT_STRING, 1775 .help = "Block driver to use for the node", 1776 }, 1777 { 1778 .name = BDRV_OPT_CACHE_DIRECT, 1779 .type = QEMU_OPT_BOOL, 1780 .help = "Bypass software writeback cache on the host", 1781 }, 1782 { 1783 .name = BDRV_OPT_CACHE_NO_FLUSH, 1784 .type = QEMU_OPT_BOOL, 1785 .help = "Ignore flush requests", 1786 }, 1787 { 1788 .name = BDRV_OPT_READ_ONLY, 1789 .type = QEMU_OPT_BOOL, 1790 .help = "Node is opened in read-only mode", 1791 }, 1792 { 1793 .name = BDRV_OPT_AUTO_READ_ONLY, 1794 .type = QEMU_OPT_BOOL, 1795 .help = "Node can become read-only if opening read-write fails", 1796 }, 1797 { 1798 .name = "detect-zeroes", 1799 .type = QEMU_OPT_STRING, 1800 .help = "try to optimize zero writes (off, on, unmap)", 1801 }, 1802 { 1803 .name = BDRV_OPT_DISCARD, 1804 .type = QEMU_OPT_STRING, 1805 .help = "discard operation (ignore/off, unmap/on)", 1806 }, 1807 { 1808 .name = BDRV_OPT_FORCE_SHARE, 1809 .type = QEMU_OPT_BOOL, 1810 .help = "always accept other writers (default: off)", 1811 }, 1812 { /* end of list */ } 1813 }, 1814 }; 1815 1816 QemuOptsList bdrv_create_opts_simple = { 1817 .name = "simple-create-opts", 1818 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head), 1819 .desc = { 1820 { 1821 .name = BLOCK_OPT_SIZE, 1822 .type = QEMU_OPT_SIZE, 1823 .help = "Virtual disk size" 1824 }, 1825 { 1826 .name = BLOCK_OPT_PREALLOC, 1827 .type = QEMU_OPT_STRING, 1828 .help = "Preallocation mode (allowed values: off)" 1829 }, 1830 { /* end of list */ } 1831 } 1832 }; 1833 1834 /* 1835 * Common part for opening disk images and files 1836 * 1837 * Removes all processed options from *options. 1838 */ 1839 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file, 1840 QDict *options, Error **errp) 1841 { 1842 int ret, open_flags; 1843 const char *filename; 1844 const char *driver_name = NULL; 1845 const char *node_name = NULL; 1846 const char *discard; 1847 QemuOpts *opts; 1848 BlockDriver *drv; 1849 Error *local_err = NULL; 1850 bool ro; 1851 1852 GLOBAL_STATE_CODE(); 1853 1854 bdrv_graph_rdlock_main_loop(); 1855 assert(bs->file == NULL); 1856 assert(options != NULL && bs->options != options); 1857 bdrv_graph_rdunlock_main_loop(); 1858 1859 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 1860 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 1861 ret = -EINVAL; 1862 goto fail_opts; 1863 } 1864 1865 update_flags_from_options(&bs->open_flags, opts); 1866 1867 driver_name = qemu_opt_get(opts, "driver"); 1868 drv = bdrv_find_format(driver_name); 1869 assert(drv != NULL); 1870 1871 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false); 1872 1873 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) { 1874 error_setg(errp, 1875 BDRV_OPT_FORCE_SHARE 1876 "=on can only be used with read-only images"); 1877 ret = -EINVAL; 1878 goto fail_opts; 1879 } 1880 1881 if (file != NULL) { 1882 bdrv_graph_rdlock_main_loop(); 1883 bdrv_refresh_filename(blk_bs(file)); 1884 bdrv_graph_rdunlock_main_loop(); 1885 1886 filename = blk_bs(file)->filename; 1887 } else { 1888 /* 1889 * Caution: while qdict_get_try_str() is fine, getting 1890 * non-string types would require more care. When @options 1891 * come from -blockdev or blockdev_add, its members are typed 1892 * according to the QAPI schema, but when they come from 1893 * -drive, they're all QString. 1894 */ 1895 filename = qdict_get_try_str(options, "filename"); 1896 } 1897 1898 if (drv->bdrv_needs_filename && (!filename || !filename[0])) { 1899 error_setg(errp, "The '%s' block driver requires a file name", 1900 drv->format_name); 1901 ret = -EINVAL; 1902 goto fail_opts; 1903 } 1904 1905 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags, 1906 drv->format_name); 1907 1908 ro = bdrv_is_read_only(bs); 1909 1910 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, ro)) { 1911 if (!ro && bdrv_is_whitelisted(drv, true)) { 1912 bdrv_graph_rdlock_main_loop(); 1913 ret = bdrv_apply_auto_read_only(bs, NULL, NULL); 1914 bdrv_graph_rdunlock_main_loop(); 1915 } else { 1916 ret = -ENOTSUP; 1917 } 1918 if (ret < 0) { 1919 error_setg(errp, 1920 !ro && bdrv_is_whitelisted(drv, true) 1921 ? "Driver '%s' can only be used for read-only devices" 1922 : "Driver '%s' is not whitelisted", 1923 drv->format_name); 1924 goto fail_opts; 1925 } 1926 } 1927 1928 /* bdrv_new() and bdrv_close() make it so */ 1929 assert(qatomic_read(&bs->copy_on_read) == 0); 1930 1931 if (bs->open_flags & BDRV_O_COPY_ON_READ) { 1932 if (!ro) { 1933 bdrv_enable_copy_on_read(bs); 1934 } else { 1935 error_setg(errp, "Can't use copy-on-read on read-only device"); 1936 ret = -EINVAL; 1937 goto fail_opts; 1938 } 1939 } 1940 1941 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD); 1942 if (discard != NULL) { 1943 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) { 1944 error_setg(errp, "Invalid discard option"); 1945 ret = -EINVAL; 1946 goto fail_opts; 1947 } 1948 } 1949 1950 bs->detect_zeroes = 1951 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err); 1952 if (local_err) { 1953 error_propagate(errp, local_err); 1954 ret = -EINVAL; 1955 goto fail_opts; 1956 } 1957 1958 if (filename != NULL) { 1959 pstrcpy(bs->filename, sizeof(bs->filename), filename); 1960 } else { 1961 bs->filename[0] = '\0'; 1962 } 1963 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename); 1964 1965 /* Open the image, either directly or using a protocol */ 1966 open_flags = bdrv_open_flags(bs, bs->open_flags); 1967 node_name = qemu_opt_get(opts, "node-name"); 1968 1969 assert(!drv->bdrv_file_open || file == NULL); 1970 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp); 1971 if (ret < 0) { 1972 goto fail_opts; 1973 } 1974 1975 qemu_opts_del(opts); 1976 return 0; 1977 1978 fail_opts: 1979 qemu_opts_del(opts); 1980 return ret; 1981 } 1982 1983 static QDict *parse_json_filename(const char *filename, Error **errp) 1984 { 1985 QObject *options_obj; 1986 QDict *options; 1987 int ret; 1988 GLOBAL_STATE_CODE(); 1989 1990 ret = strstart(filename, "json:", &filename); 1991 assert(ret); 1992 1993 options_obj = qobject_from_json(filename, errp); 1994 if (!options_obj) { 1995 error_prepend(errp, "Could not parse the JSON options: "); 1996 return NULL; 1997 } 1998 1999 options = qobject_to(QDict, options_obj); 2000 if (!options) { 2001 qobject_unref(options_obj); 2002 error_setg(errp, "Invalid JSON object given"); 2003 return NULL; 2004 } 2005 2006 qdict_flatten(options); 2007 2008 return options; 2009 } 2010 2011 static void parse_json_protocol(QDict *options, const char **pfilename, 2012 Error **errp) 2013 { 2014 QDict *json_options; 2015 Error *local_err = NULL; 2016 GLOBAL_STATE_CODE(); 2017 2018 /* Parse json: pseudo-protocol */ 2019 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) { 2020 return; 2021 } 2022 2023 json_options = parse_json_filename(*pfilename, &local_err); 2024 if (local_err) { 2025 error_propagate(errp, local_err); 2026 return; 2027 } 2028 2029 /* Options given in the filename have lower priority than options 2030 * specified directly */ 2031 qdict_join(options, json_options, false); 2032 qobject_unref(json_options); 2033 *pfilename = NULL; 2034 } 2035 2036 /* 2037 * Fills in default options for opening images and converts the legacy 2038 * filename/flags pair to option QDict entries. 2039 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a 2040 * block driver has been specified explicitly. 2041 */ 2042 static int bdrv_fill_options(QDict **options, const char *filename, 2043 int *flags, Error **errp) 2044 { 2045 const char *drvname; 2046 bool protocol = *flags & BDRV_O_PROTOCOL; 2047 bool parse_filename = false; 2048 BlockDriver *drv = NULL; 2049 Error *local_err = NULL; 2050 2051 GLOBAL_STATE_CODE(); 2052 2053 /* 2054 * Caution: while qdict_get_try_str() is fine, getting non-string 2055 * types would require more care. When @options come from 2056 * -blockdev or blockdev_add, its members are typed according to 2057 * the QAPI schema, but when they come from -drive, they're all 2058 * QString. 2059 */ 2060 drvname = qdict_get_try_str(*options, "driver"); 2061 if (drvname) { 2062 drv = bdrv_find_format(drvname); 2063 if (!drv) { 2064 error_setg(errp, "Unknown driver '%s'", drvname); 2065 return -ENOENT; 2066 } 2067 /* If the user has explicitly specified the driver, this choice should 2068 * override the BDRV_O_PROTOCOL flag */ 2069 protocol = drv->bdrv_file_open; 2070 } 2071 2072 if (protocol) { 2073 *flags |= BDRV_O_PROTOCOL; 2074 } else { 2075 *flags &= ~BDRV_O_PROTOCOL; 2076 } 2077 2078 /* Translate cache options from flags into options */ 2079 update_options_from_flags(*options, *flags); 2080 2081 /* Fetch the file name from the options QDict if necessary */ 2082 if (protocol && filename) { 2083 if (!qdict_haskey(*options, "filename")) { 2084 qdict_put_str(*options, "filename", filename); 2085 parse_filename = true; 2086 } else { 2087 error_setg(errp, "Can't specify 'file' and 'filename' options at " 2088 "the same time"); 2089 return -EINVAL; 2090 } 2091 } 2092 2093 /* Find the right block driver */ 2094 /* See cautionary note on accessing @options above */ 2095 filename = qdict_get_try_str(*options, "filename"); 2096 2097 if (!drvname && protocol) { 2098 if (filename) { 2099 drv = bdrv_find_protocol(filename, parse_filename, errp); 2100 if (!drv) { 2101 return -EINVAL; 2102 } 2103 2104 drvname = drv->format_name; 2105 qdict_put_str(*options, "driver", drvname); 2106 } else { 2107 error_setg(errp, "Must specify either driver or file"); 2108 return -EINVAL; 2109 } 2110 } 2111 2112 assert(drv || !protocol); 2113 2114 /* Driver-specific filename parsing */ 2115 if (drv && drv->bdrv_parse_filename && parse_filename) { 2116 drv->bdrv_parse_filename(filename, *options, &local_err); 2117 if (local_err) { 2118 error_propagate(errp, local_err); 2119 return -EINVAL; 2120 } 2121 2122 if (!drv->bdrv_needs_filename) { 2123 qdict_del(*options, "filename"); 2124 } 2125 } 2126 2127 return 0; 2128 } 2129 2130 typedef struct BlockReopenQueueEntry { 2131 bool prepared; 2132 BDRVReopenState state; 2133 QTAILQ_ENTRY(BlockReopenQueueEntry) entry; 2134 } BlockReopenQueueEntry; 2135 2136 /* 2137 * Return the flags that @bs will have after the reopens in @q have 2138 * successfully completed. If @q is NULL (or @bs is not contained in @q), 2139 * return the current flags. 2140 */ 2141 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs) 2142 { 2143 BlockReopenQueueEntry *entry; 2144 2145 if (q != NULL) { 2146 QTAILQ_FOREACH(entry, q, entry) { 2147 if (entry->state.bs == bs) { 2148 return entry->state.flags; 2149 } 2150 } 2151 } 2152 2153 return bs->open_flags; 2154 } 2155 2156 /* Returns whether the image file can be written to after the reopen queue @q 2157 * has been successfully applied, or right now if @q is NULL. */ 2158 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs, 2159 BlockReopenQueue *q) 2160 { 2161 int flags = bdrv_reopen_get_flags(q, bs); 2162 2163 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR; 2164 } 2165 2166 /* 2167 * Return whether the BDS can be written to. This is not necessarily 2168 * the same as !bdrv_is_read_only(bs), as inactivated images may not 2169 * be written to but do not count as read-only images. 2170 */ 2171 bool bdrv_is_writable(BlockDriverState *bs) 2172 { 2173 IO_CODE(); 2174 return bdrv_is_writable_after_reopen(bs, NULL); 2175 } 2176 2177 static char *bdrv_child_user_desc(BdrvChild *c) 2178 { 2179 GLOBAL_STATE_CODE(); 2180 return c->klass->get_parent_desc(c); 2181 } 2182 2183 /* 2184 * Check that @a allows everything that @b needs. @a and @b must reference same 2185 * child node. 2186 */ 2187 static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp) 2188 { 2189 const char *child_bs_name; 2190 g_autofree char *a_user = NULL; 2191 g_autofree char *b_user = NULL; 2192 g_autofree char *perms = NULL; 2193 2194 assert(a->bs); 2195 assert(a->bs == b->bs); 2196 GLOBAL_STATE_CODE(); 2197 2198 if ((b->perm & a->shared_perm) == b->perm) { 2199 return true; 2200 } 2201 2202 child_bs_name = bdrv_get_node_name(b->bs); 2203 a_user = bdrv_child_user_desc(a); 2204 b_user = bdrv_child_user_desc(b); 2205 perms = bdrv_perm_names(b->perm & ~a->shared_perm); 2206 2207 error_setg(errp, "Permission conflict on node '%s': permissions '%s' are " 2208 "both required by %s (uses node '%s' as '%s' child) and " 2209 "unshared by %s (uses node '%s' as '%s' child).", 2210 child_bs_name, perms, 2211 b_user, child_bs_name, b->name, 2212 a_user, child_bs_name, a->name); 2213 2214 return false; 2215 } 2216 2217 static bool GRAPH_RDLOCK 2218 bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp) 2219 { 2220 BdrvChild *a, *b; 2221 GLOBAL_STATE_CODE(); 2222 2223 /* 2224 * During the loop we'll look at each pair twice. That's correct because 2225 * bdrv_a_allow_b() is asymmetric and we should check each pair in both 2226 * directions. 2227 */ 2228 QLIST_FOREACH(a, &bs->parents, next_parent) { 2229 QLIST_FOREACH(b, &bs->parents, next_parent) { 2230 if (a == b) { 2231 continue; 2232 } 2233 2234 if (!bdrv_a_allow_b(a, b, errp)) { 2235 return true; 2236 } 2237 } 2238 } 2239 2240 return false; 2241 } 2242 2243 static void GRAPH_RDLOCK 2244 bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs, 2245 BdrvChild *c, BdrvChildRole role, 2246 BlockReopenQueue *reopen_queue, 2247 uint64_t parent_perm, uint64_t parent_shared, 2248 uint64_t *nperm, uint64_t *nshared) 2249 { 2250 assert(bs->drv && bs->drv->bdrv_child_perm); 2251 GLOBAL_STATE_CODE(); 2252 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue, 2253 parent_perm, parent_shared, 2254 nperm, nshared); 2255 /* TODO Take force_share from reopen_queue */ 2256 if (child_bs && child_bs->force_share) { 2257 *nshared = BLK_PERM_ALL; 2258 } 2259 } 2260 2261 /* 2262 * Adds the whole subtree of @bs (including @bs itself) to the @list (except for 2263 * nodes that are already in the @list, of course) so that final list is 2264 * topologically sorted. Return the result (GSList @list object is updated, so 2265 * don't use old reference after function call). 2266 * 2267 * On function start @list must be already topologically sorted and for any node 2268 * in the @list the whole subtree of the node must be in the @list as well. The 2269 * simplest way to satisfy this criteria: use only result of 2270 * bdrv_topological_dfs() or NULL as @list parameter. 2271 */ 2272 static GSList * GRAPH_RDLOCK 2273 bdrv_topological_dfs(GSList *list, GHashTable *found, BlockDriverState *bs) 2274 { 2275 BdrvChild *child; 2276 g_autoptr(GHashTable) local_found = NULL; 2277 2278 GLOBAL_STATE_CODE(); 2279 2280 if (!found) { 2281 assert(!list); 2282 found = local_found = g_hash_table_new(NULL, NULL); 2283 } 2284 2285 if (g_hash_table_contains(found, bs)) { 2286 return list; 2287 } 2288 g_hash_table_add(found, bs); 2289 2290 QLIST_FOREACH(child, &bs->children, next) { 2291 list = bdrv_topological_dfs(list, found, child->bs); 2292 } 2293 2294 return g_slist_prepend(list, bs); 2295 } 2296 2297 typedef struct BdrvChildSetPermState { 2298 BdrvChild *child; 2299 uint64_t old_perm; 2300 uint64_t old_shared_perm; 2301 } BdrvChildSetPermState; 2302 2303 static void bdrv_child_set_perm_abort(void *opaque) 2304 { 2305 BdrvChildSetPermState *s = opaque; 2306 2307 GLOBAL_STATE_CODE(); 2308 2309 s->child->perm = s->old_perm; 2310 s->child->shared_perm = s->old_shared_perm; 2311 } 2312 2313 static TransactionActionDrv bdrv_child_set_pem_drv = { 2314 .abort = bdrv_child_set_perm_abort, 2315 .clean = g_free, 2316 }; 2317 2318 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, 2319 uint64_t shared, Transaction *tran) 2320 { 2321 BdrvChildSetPermState *s = g_new(BdrvChildSetPermState, 1); 2322 GLOBAL_STATE_CODE(); 2323 2324 *s = (BdrvChildSetPermState) { 2325 .child = c, 2326 .old_perm = c->perm, 2327 .old_shared_perm = c->shared_perm, 2328 }; 2329 2330 c->perm = perm; 2331 c->shared_perm = shared; 2332 2333 tran_add(tran, &bdrv_child_set_pem_drv, s); 2334 } 2335 2336 static void GRAPH_RDLOCK bdrv_drv_set_perm_commit(void *opaque) 2337 { 2338 BlockDriverState *bs = opaque; 2339 uint64_t cumulative_perms, cumulative_shared_perms; 2340 GLOBAL_STATE_CODE(); 2341 2342 if (bs->drv->bdrv_set_perm) { 2343 bdrv_get_cumulative_perm(bs, &cumulative_perms, 2344 &cumulative_shared_perms); 2345 bs->drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms); 2346 } 2347 } 2348 2349 static void GRAPH_RDLOCK bdrv_drv_set_perm_abort(void *opaque) 2350 { 2351 BlockDriverState *bs = opaque; 2352 GLOBAL_STATE_CODE(); 2353 2354 if (bs->drv->bdrv_abort_perm_update) { 2355 bs->drv->bdrv_abort_perm_update(bs); 2356 } 2357 } 2358 2359 TransactionActionDrv bdrv_drv_set_perm_drv = { 2360 .abort = bdrv_drv_set_perm_abort, 2361 .commit = bdrv_drv_set_perm_commit, 2362 }; 2363 2364 /* 2365 * After calling this function, the transaction @tran may only be completed 2366 * while holding a reader lock for the graph. 2367 */ 2368 static int GRAPH_RDLOCK 2369 bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared_perm, 2370 Transaction *tran, Error **errp) 2371 { 2372 GLOBAL_STATE_CODE(); 2373 if (!bs->drv) { 2374 return 0; 2375 } 2376 2377 if (bs->drv->bdrv_check_perm) { 2378 int ret = bs->drv->bdrv_check_perm(bs, perm, shared_perm, errp); 2379 if (ret < 0) { 2380 return ret; 2381 } 2382 } 2383 2384 if (tran) { 2385 tran_add(tran, &bdrv_drv_set_perm_drv, bs); 2386 } 2387 2388 return 0; 2389 } 2390 2391 typedef struct BdrvReplaceChildState { 2392 BdrvChild *child; 2393 BlockDriverState *old_bs; 2394 } BdrvReplaceChildState; 2395 2396 static void GRAPH_WRLOCK bdrv_replace_child_commit(void *opaque) 2397 { 2398 BdrvReplaceChildState *s = opaque; 2399 GLOBAL_STATE_CODE(); 2400 2401 bdrv_schedule_unref(s->old_bs); 2402 } 2403 2404 static void GRAPH_WRLOCK bdrv_replace_child_abort(void *opaque) 2405 { 2406 BdrvReplaceChildState *s = opaque; 2407 BlockDriverState *new_bs = s->child->bs; 2408 2409 GLOBAL_STATE_CODE(); 2410 assert_bdrv_graph_writable(); 2411 2412 /* old_bs reference is transparently moved from @s to @s->child */ 2413 if (!s->child->bs) { 2414 /* 2415 * The parents were undrained when removing old_bs from the child. New 2416 * requests can't have been made, though, because the child was empty. 2417 * 2418 * TODO Make bdrv_replace_child_noperm() transactionable to avoid 2419 * undraining the parent in the first place. Once this is done, having 2420 * new_bs drained when calling bdrv_replace_child_tran() is not a 2421 * requirement any more. 2422 */ 2423 bdrv_parent_drained_begin_single(s->child); 2424 assert(!bdrv_parent_drained_poll_single(s->child)); 2425 } 2426 assert(s->child->quiesced_parent); 2427 bdrv_replace_child_noperm(s->child, s->old_bs); 2428 2429 bdrv_unref(new_bs); 2430 } 2431 2432 static TransactionActionDrv bdrv_replace_child_drv = { 2433 .commit = bdrv_replace_child_commit, 2434 .abort = bdrv_replace_child_abort, 2435 .clean = g_free, 2436 }; 2437 2438 /* 2439 * bdrv_replace_child_tran 2440 * 2441 * Note: real unref of old_bs is done only on commit. 2442 * 2443 * Both @child->bs and @new_bs (if non-NULL) must be drained. @new_bs must be 2444 * kept drained until the transaction is completed. 2445 * 2446 * After calling this function, the transaction @tran may only be completed 2447 * while holding a writer lock for the graph. 2448 * 2449 * The function doesn't update permissions, caller is responsible for this. 2450 */ 2451 static void GRAPH_WRLOCK 2452 bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs, 2453 Transaction *tran) 2454 { 2455 BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1); 2456 2457 assert(child->quiesced_parent); 2458 assert(!new_bs || new_bs->quiesce_counter); 2459 2460 *s = (BdrvReplaceChildState) { 2461 .child = child, 2462 .old_bs = child->bs, 2463 }; 2464 tran_add(tran, &bdrv_replace_child_drv, s); 2465 2466 if (new_bs) { 2467 bdrv_ref(new_bs); 2468 } 2469 2470 bdrv_replace_child_noperm(child, new_bs); 2471 /* old_bs reference is transparently moved from @child to @s */ 2472 } 2473 2474 /* 2475 * Refresh permissions in @bs subtree. The function is intended to be called 2476 * after some graph modification that was done without permission update. 2477 * 2478 * After calling this function, the transaction @tran may only be completed 2479 * while holding a reader lock for the graph. 2480 */ 2481 static int GRAPH_RDLOCK 2482 bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q, 2483 Transaction *tran, Error **errp) 2484 { 2485 BlockDriver *drv = bs->drv; 2486 BdrvChild *c; 2487 int ret; 2488 uint64_t cumulative_perms, cumulative_shared_perms; 2489 GLOBAL_STATE_CODE(); 2490 2491 bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms); 2492 2493 /* Write permissions never work with read-only images */ 2494 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && 2495 !bdrv_is_writable_after_reopen(bs, q)) 2496 { 2497 if (!bdrv_is_writable_after_reopen(bs, NULL)) { 2498 error_setg(errp, "Block node is read-only"); 2499 } else { 2500 error_setg(errp, "Read-only block node '%s' cannot support " 2501 "read-write users", bdrv_get_node_name(bs)); 2502 } 2503 2504 return -EPERM; 2505 } 2506 2507 /* 2508 * Unaligned requests will automatically be aligned to bl.request_alignment 2509 * and without RESIZE we can't extend requests to write to space beyond the 2510 * end of the image, so it's required that the image size is aligned. 2511 */ 2512 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && 2513 !(cumulative_perms & BLK_PERM_RESIZE)) 2514 { 2515 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) { 2516 error_setg(errp, "Cannot get 'write' permission without 'resize': " 2517 "Image size is not a multiple of request " 2518 "alignment"); 2519 return -EPERM; 2520 } 2521 } 2522 2523 /* Check this node */ 2524 if (!drv) { 2525 return 0; 2526 } 2527 2528 ret = bdrv_drv_set_perm(bs, cumulative_perms, cumulative_shared_perms, tran, 2529 errp); 2530 if (ret < 0) { 2531 return ret; 2532 } 2533 2534 /* Drivers that never have children can omit .bdrv_child_perm() */ 2535 if (!drv->bdrv_child_perm) { 2536 assert(QLIST_EMPTY(&bs->children)); 2537 return 0; 2538 } 2539 2540 /* Check all children */ 2541 QLIST_FOREACH(c, &bs->children, next) { 2542 uint64_t cur_perm, cur_shared; 2543 2544 bdrv_child_perm(bs, c->bs, c, c->role, q, 2545 cumulative_perms, cumulative_shared_perms, 2546 &cur_perm, &cur_shared); 2547 bdrv_child_set_perm(c, cur_perm, cur_shared, tran); 2548 } 2549 2550 return 0; 2551 } 2552 2553 /* 2554 * @list is a product of bdrv_topological_dfs() (may be called several times) - 2555 * a topologically sorted subgraph. 2556 * 2557 * After calling this function, the transaction @tran may only be completed 2558 * while holding a reader lock for the graph. 2559 */ 2560 static int GRAPH_RDLOCK 2561 bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran, 2562 Error **errp) 2563 { 2564 int ret; 2565 BlockDriverState *bs; 2566 GLOBAL_STATE_CODE(); 2567 2568 for ( ; list; list = list->next) { 2569 bs = list->data; 2570 2571 if (bdrv_parent_perms_conflict(bs, errp)) { 2572 return -EINVAL; 2573 } 2574 2575 ret = bdrv_node_refresh_perm(bs, q, tran, errp); 2576 if (ret < 0) { 2577 return ret; 2578 } 2579 } 2580 2581 return 0; 2582 } 2583 2584 /* 2585 * @list is any list of nodes. List is completed by all subtrees and 2586 * topologically sorted. It's not a problem if some node occurs in the @list 2587 * several times. 2588 * 2589 * After calling this function, the transaction @tran may only be completed 2590 * while holding a reader lock for the graph. 2591 */ 2592 static int GRAPH_RDLOCK 2593 bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran, 2594 Error **errp) 2595 { 2596 g_autoptr(GHashTable) found = g_hash_table_new(NULL, NULL); 2597 g_autoptr(GSList) refresh_list = NULL; 2598 2599 for ( ; list; list = list->next) { 2600 refresh_list = bdrv_topological_dfs(refresh_list, found, list->data); 2601 } 2602 2603 return bdrv_do_refresh_perms(refresh_list, q, tran, errp); 2604 } 2605 2606 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm, 2607 uint64_t *shared_perm) 2608 { 2609 BdrvChild *c; 2610 uint64_t cumulative_perms = 0; 2611 uint64_t cumulative_shared_perms = BLK_PERM_ALL; 2612 2613 GLOBAL_STATE_CODE(); 2614 2615 QLIST_FOREACH(c, &bs->parents, next_parent) { 2616 cumulative_perms |= c->perm; 2617 cumulative_shared_perms &= c->shared_perm; 2618 } 2619 2620 *perm = cumulative_perms; 2621 *shared_perm = cumulative_shared_perms; 2622 } 2623 2624 char *bdrv_perm_names(uint64_t perm) 2625 { 2626 struct perm_name { 2627 uint64_t perm; 2628 const char *name; 2629 } permissions[] = { 2630 { BLK_PERM_CONSISTENT_READ, "consistent read" }, 2631 { BLK_PERM_WRITE, "write" }, 2632 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" }, 2633 { BLK_PERM_RESIZE, "resize" }, 2634 { 0, NULL } 2635 }; 2636 2637 GString *result = g_string_sized_new(30); 2638 struct perm_name *p; 2639 2640 for (p = permissions; p->name; p++) { 2641 if (perm & p->perm) { 2642 if (result->len > 0) { 2643 g_string_append(result, ", "); 2644 } 2645 g_string_append(result, p->name); 2646 } 2647 } 2648 2649 return g_string_free(result, FALSE); 2650 } 2651 2652 2653 /* 2654 * @tran is allowed to be NULL. In this case no rollback is possible. 2655 * 2656 * After calling this function, the transaction @tran may only be completed 2657 * while holding a reader lock for the graph. 2658 */ 2659 static int GRAPH_RDLOCK 2660 bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp) 2661 { 2662 int ret; 2663 Transaction *local_tran = NULL; 2664 g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs); 2665 GLOBAL_STATE_CODE(); 2666 2667 if (!tran) { 2668 tran = local_tran = tran_new(); 2669 } 2670 2671 ret = bdrv_do_refresh_perms(list, NULL, tran, errp); 2672 2673 if (local_tran) { 2674 tran_finalize(local_tran, ret); 2675 } 2676 2677 return ret; 2678 } 2679 2680 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, 2681 Error **errp) 2682 { 2683 Error *local_err = NULL; 2684 Transaction *tran = tran_new(); 2685 int ret; 2686 2687 GLOBAL_STATE_CODE(); 2688 2689 bdrv_child_set_perm(c, perm, shared, tran); 2690 2691 ret = bdrv_refresh_perms(c->bs, tran, &local_err); 2692 2693 tran_finalize(tran, ret); 2694 2695 if (ret < 0) { 2696 if ((perm & ~c->perm) || (c->shared_perm & ~shared)) { 2697 /* tighten permissions */ 2698 error_propagate(errp, local_err); 2699 } else { 2700 /* 2701 * Our caller may intend to only loosen restrictions and 2702 * does not expect this function to fail. Errors are not 2703 * fatal in such a case, so we can just hide them from our 2704 * caller. 2705 */ 2706 error_free(local_err); 2707 ret = 0; 2708 } 2709 } 2710 2711 return ret; 2712 } 2713 2714 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp) 2715 { 2716 uint64_t parent_perms, parent_shared; 2717 uint64_t perms, shared; 2718 2719 GLOBAL_STATE_CODE(); 2720 2721 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared); 2722 bdrv_child_perm(bs, c->bs, c, c->role, NULL, 2723 parent_perms, parent_shared, &perms, &shared); 2724 2725 return bdrv_child_try_set_perm(c, perms, shared, errp); 2726 } 2727 2728 /* 2729 * Default implementation for .bdrv_child_perm() for block filters: 2730 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the 2731 * filtered child. 2732 */ 2733 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c, 2734 BdrvChildRole role, 2735 BlockReopenQueue *reopen_queue, 2736 uint64_t perm, uint64_t shared, 2737 uint64_t *nperm, uint64_t *nshared) 2738 { 2739 GLOBAL_STATE_CODE(); 2740 *nperm = perm & DEFAULT_PERM_PASSTHROUGH; 2741 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED; 2742 } 2743 2744 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c, 2745 BdrvChildRole role, 2746 BlockReopenQueue *reopen_queue, 2747 uint64_t perm, uint64_t shared, 2748 uint64_t *nperm, uint64_t *nshared) 2749 { 2750 assert(role & BDRV_CHILD_COW); 2751 GLOBAL_STATE_CODE(); 2752 2753 /* 2754 * We want consistent read from backing files if the parent needs it. 2755 * No other operations are performed on backing files. 2756 */ 2757 perm &= BLK_PERM_CONSISTENT_READ; 2758 2759 /* 2760 * If the parent can deal with changing data, we're okay with a 2761 * writable and resizable backing file. 2762 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? 2763 */ 2764 if (shared & BLK_PERM_WRITE) { 2765 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE; 2766 } else { 2767 shared = 0; 2768 } 2769 2770 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED; 2771 2772 if (bs->open_flags & BDRV_O_INACTIVE) { 2773 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2774 } 2775 2776 *nperm = perm; 2777 *nshared = shared; 2778 } 2779 2780 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c, 2781 BdrvChildRole role, 2782 BlockReopenQueue *reopen_queue, 2783 uint64_t perm, uint64_t shared, 2784 uint64_t *nperm, uint64_t *nshared) 2785 { 2786 int flags; 2787 2788 GLOBAL_STATE_CODE(); 2789 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)); 2790 2791 flags = bdrv_reopen_get_flags(reopen_queue, bs); 2792 2793 /* 2794 * Apart from the modifications below, the same permissions are 2795 * forwarded and left alone as for filters 2796 */ 2797 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2798 perm, shared, &perm, &shared); 2799 2800 if (role & BDRV_CHILD_METADATA) { 2801 /* Format drivers may touch metadata even if the guest doesn't write */ 2802 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) { 2803 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2804 } 2805 2806 /* 2807 * bs->file always needs to be consistent because of the 2808 * metadata. We can never allow other users to resize or write 2809 * to it. 2810 */ 2811 if (!(flags & BDRV_O_NO_IO)) { 2812 perm |= BLK_PERM_CONSISTENT_READ; 2813 } 2814 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); 2815 } 2816 2817 if (role & BDRV_CHILD_DATA) { 2818 /* 2819 * Technically, everything in this block is a subset of the 2820 * BDRV_CHILD_METADATA path taken above, and so this could 2821 * be an "else if" branch. However, that is not obvious, and 2822 * this function is not performance critical, therefore we let 2823 * this be an independent "if". 2824 */ 2825 2826 /* 2827 * We cannot allow other users to resize the file because the 2828 * format driver might have some assumptions about the size 2829 * (e.g. because it is stored in metadata, or because the file 2830 * is split into fixed-size data files). 2831 */ 2832 shared &= ~BLK_PERM_RESIZE; 2833 2834 /* 2835 * WRITE_UNCHANGED often cannot be performed as such on the 2836 * data file. For example, the qcow2 driver may still need to 2837 * write copied clusters on copy-on-read. 2838 */ 2839 if (perm & BLK_PERM_WRITE_UNCHANGED) { 2840 perm |= BLK_PERM_WRITE; 2841 } 2842 2843 /* 2844 * If the data file is written to, the format driver may 2845 * expect to be able to resize it by writing beyond the EOF. 2846 */ 2847 if (perm & BLK_PERM_WRITE) { 2848 perm |= BLK_PERM_RESIZE; 2849 } 2850 } 2851 2852 if (bs->open_flags & BDRV_O_INACTIVE) { 2853 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2854 } 2855 2856 *nperm = perm; 2857 *nshared = shared; 2858 } 2859 2860 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c, 2861 BdrvChildRole role, BlockReopenQueue *reopen_queue, 2862 uint64_t perm, uint64_t shared, 2863 uint64_t *nperm, uint64_t *nshared) 2864 { 2865 GLOBAL_STATE_CODE(); 2866 if (role & BDRV_CHILD_FILTERED) { 2867 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | 2868 BDRV_CHILD_COW))); 2869 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2870 perm, shared, nperm, nshared); 2871 } else if (role & BDRV_CHILD_COW) { 2872 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA))); 2873 bdrv_default_perms_for_cow(bs, c, role, reopen_queue, 2874 perm, shared, nperm, nshared); 2875 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) { 2876 bdrv_default_perms_for_storage(bs, c, role, reopen_queue, 2877 perm, shared, nperm, nshared); 2878 } else { 2879 g_assert_not_reached(); 2880 } 2881 } 2882 2883 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) 2884 { 2885 static const uint64_t permissions[] = { 2886 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ, 2887 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE, 2888 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED, 2889 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE, 2890 }; 2891 2892 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX); 2893 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1); 2894 2895 assert(qapi_perm < BLOCK_PERMISSION__MAX); 2896 2897 return permissions[qapi_perm]; 2898 } 2899 2900 /* 2901 * Replaces the node that a BdrvChild points to without updating permissions. 2902 * 2903 * If @new_bs is non-NULL, the parent of @child must already be drained through 2904 * @child and the caller must hold the AioContext lock for @new_bs. 2905 */ 2906 static void GRAPH_WRLOCK 2907 bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs) 2908 { 2909 BlockDriverState *old_bs = child->bs; 2910 int new_bs_quiesce_counter; 2911 2912 assert(!child->frozen); 2913 2914 /* 2915 * If we want to change the BdrvChild to point to a drained node as its new 2916 * child->bs, we need to make sure that its new parent is drained, too. In 2917 * other words, either child->quiesce_parent must already be true or we must 2918 * be able to set it and keep the parent's quiesce_counter consistent with 2919 * that, but without polling or starting new requests (this function 2920 * guarantees that it doesn't poll, and starting new requests would be 2921 * against the invariants of drain sections). 2922 * 2923 * To keep things simple, we pick the first option (child->quiesce_parent 2924 * must already be true). We also generalise the rule a bit to make it 2925 * easier to verify in callers and more likely to be covered in test cases: 2926 * The parent must be quiesced through this child even if new_bs isn't 2927 * currently drained. 2928 * 2929 * The only exception is for callers that always pass new_bs == NULL. In 2930 * this case, we obviously never need to consider the case of a drained 2931 * new_bs, so we can keep the callers simpler by allowing them not to drain 2932 * the parent. 2933 */ 2934 assert(!new_bs || child->quiesced_parent); 2935 assert(old_bs != new_bs); 2936 GLOBAL_STATE_CODE(); 2937 2938 if (old_bs && new_bs) { 2939 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs)); 2940 } 2941 2942 if (old_bs) { 2943 if (child->klass->detach) { 2944 child->klass->detach(child); 2945 } 2946 QLIST_REMOVE(child, next_parent); 2947 } 2948 2949 child->bs = new_bs; 2950 2951 if (new_bs) { 2952 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); 2953 if (child->klass->attach) { 2954 child->klass->attach(child); 2955 } 2956 } 2957 2958 /* 2959 * If the parent was drained through this BdrvChild previously, but new_bs 2960 * is not drained, allow requests to come in only after the new node has 2961 * been attached. 2962 */ 2963 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); 2964 if (!new_bs_quiesce_counter && child->quiesced_parent) { 2965 bdrv_parent_drained_end_single(child); 2966 } 2967 } 2968 2969 /** 2970 * Free the given @child. 2971 * 2972 * The child must be empty (i.e. `child->bs == NULL`) and it must be 2973 * unused (i.e. not in a children list). 2974 */ 2975 static void bdrv_child_free(BdrvChild *child) 2976 { 2977 assert(!child->bs); 2978 GLOBAL_STATE_CODE(); 2979 GRAPH_RDLOCK_GUARD_MAINLOOP(); 2980 2981 assert(!child->next.le_prev); /* not in children list */ 2982 2983 g_free(child->name); 2984 g_free(child); 2985 } 2986 2987 typedef struct BdrvAttachChildCommonState { 2988 BdrvChild *child; 2989 AioContext *old_parent_ctx; 2990 AioContext *old_child_ctx; 2991 } BdrvAttachChildCommonState; 2992 2993 static void GRAPH_WRLOCK bdrv_attach_child_common_abort(void *opaque) 2994 { 2995 BdrvAttachChildCommonState *s = opaque; 2996 BlockDriverState *bs = s->child->bs; 2997 2998 GLOBAL_STATE_CODE(); 2999 assert_bdrv_graph_writable(); 3000 3001 bdrv_replace_child_noperm(s->child, NULL); 3002 3003 if (bdrv_get_aio_context(bs) != s->old_child_ctx) { 3004 bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort); 3005 } 3006 3007 if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) { 3008 Transaction *tran; 3009 GHashTable *visited; 3010 bool ret; 3011 3012 tran = tran_new(); 3013 3014 /* No need to visit `child`, because it has been detached already */ 3015 visited = g_hash_table_new(NULL, NULL); 3016 ret = s->child->klass->change_aio_ctx(s->child, s->old_parent_ctx, 3017 visited, tran, &error_abort); 3018 g_hash_table_destroy(visited); 3019 3020 /* transaction is supposed to always succeed */ 3021 assert(ret == true); 3022 tran_commit(tran); 3023 } 3024 3025 bdrv_schedule_unref(bs); 3026 bdrv_child_free(s->child); 3027 } 3028 3029 static TransactionActionDrv bdrv_attach_child_common_drv = { 3030 .abort = bdrv_attach_child_common_abort, 3031 .clean = g_free, 3032 }; 3033 3034 /* 3035 * Common part of attaching bdrv child to bs or to blk or to job 3036 * 3037 * Function doesn't update permissions, caller is responsible for this. 3038 * 3039 * After calling this function, the transaction @tran may only be completed 3040 * while holding a writer lock for the graph. 3041 * 3042 * Returns new created child. 3043 * 3044 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and 3045 * @child_bs can move to a different AioContext in this function. Callers must 3046 * make sure that their AioContext locking is still correct after this. 3047 */ 3048 static BdrvChild * GRAPH_WRLOCK 3049 bdrv_attach_child_common(BlockDriverState *child_bs, 3050 const char *child_name, 3051 const BdrvChildClass *child_class, 3052 BdrvChildRole child_role, 3053 uint64_t perm, uint64_t shared_perm, 3054 void *opaque, 3055 Transaction *tran, Error **errp) 3056 { 3057 BdrvChild *new_child; 3058 AioContext *parent_ctx; 3059 AioContext *child_ctx = bdrv_get_aio_context(child_bs); 3060 3061 assert(child_class->get_parent_desc); 3062 GLOBAL_STATE_CODE(); 3063 3064 new_child = g_new(BdrvChild, 1); 3065 *new_child = (BdrvChild) { 3066 .bs = NULL, 3067 .name = g_strdup(child_name), 3068 .klass = child_class, 3069 .role = child_role, 3070 .perm = perm, 3071 .shared_perm = shared_perm, 3072 .opaque = opaque, 3073 }; 3074 3075 /* 3076 * If the AioContexts don't match, first try to move the subtree of 3077 * child_bs into the AioContext of the new parent. If this doesn't work, 3078 * try moving the parent into the AioContext of child_bs instead. 3079 */ 3080 parent_ctx = bdrv_child_get_parent_aio_context(new_child); 3081 if (child_ctx != parent_ctx) { 3082 Error *local_err = NULL; 3083 int ret = bdrv_try_change_aio_context(child_bs, parent_ctx, NULL, 3084 &local_err); 3085 3086 if (ret < 0 && child_class->change_aio_ctx) { 3087 Transaction *aio_ctx_tran = tran_new(); 3088 GHashTable *visited = g_hash_table_new(NULL, NULL); 3089 bool ret_child; 3090 3091 g_hash_table_add(visited, new_child); 3092 ret_child = child_class->change_aio_ctx(new_child, child_ctx, 3093 visited, aio_ctx_tran, 3094 NULL); 3095 if (ret_child == true) { 3096 error_free(local_err); 3097 ret = 0; 3098 } 3099 tran_finalize(aio_ctx_tran, ret_child == true ? 0 : -1); 3100 g_hash_table_destroy(visited); 3101 } 3102 3103 if (ret < 0) { 3104 error_propagate(errp, local_err); 3105 bdrv_child_free(new_child); 3106 return NULL; 3107 } 3108 } 3109 3110 bdrv_ref(child_bs); 3111 /* 3112 * Let every new BdrvChild start with a drained parent. Inserting the child 3113 * in the graph with bdrv_replace_child_noperm() will undrain it if 3114 * @child_bs is not drained. 3115 * 3116 * The child was only just created and is not yet visible in global state 3117 * until bdrv_replace_child_noperm() inserts it into the graph, so nobody 3118 * could have sent requests and polling is not necessary. 3119 * 3120 * Note that this means that the parent isn't fully drained yet, we only 3121 * stop new requests from coming in. This is fine, we don't care about the 3122 * old requests here, they are not for this child. If another place enters a 3123 * drain section for the same parent, but wants it to be fully quiesced, it 3124 * will not run most of the the code in .drained_begin() again (which is not 3125 * a problem, we already did this), but it will still poll until the parent 3126 * is fully quiesced, so it will not be negatively affected either. 3127 */ 3128 bdrv_parent_drained_begin_single(new_child); 3129 bdrv_replace_child_noperm(new_child, child_bs); 3130 3131 BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1); 3132 *s = (BdrvAttachChildCommonState) { 3133 .child = new_child, 3134 .old_parent_ctx = parent_ctx, 3135 .old_child_ctx = child_ctx, 3136 }; 3137 tran_add(tran, &bdrv_attach_child_common_drv, s); 3138 3139 return new_child; 3140 } 3141 3142 /* 3143 * Function doesn't update permissions, caller is responsible for this. 3144 * 3145 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and 3146 * @child_bs can move to a different AioContext in this function. Callers must 3147 * make sure that their AioContext locking is still correct after this. 3148 * 3149 * After calling this function, the transaction @tran may only be completed 3150 * while holding a writer lock for the graph. 3151 */ 3152 static BdrvChild * GRAPH_WRLOCK 3153 bdrv_attach_child_noperm(BlockDriverState *parent_bs, 3154 BlockDriverState *child_bs, 3155 const char *child_name, 3156 const BdrvChildClass *child_class, 3157 BdrvChildRole child_role, 3158 Transaction *tran, 3159 Error **errp) 3160 { 3161 uint64_t perm, shared_perm; 3162 3163 assert(parent_bs->drv); 3164 GLOBAL_STATE_CODE(); 3165 3166 if (bdrv_recurse_has_child(child_bs, parent_bs)) { 3167 error_setg(errp, "Making '%s' a %s child of '%s' would create a cycle", 3168 child_bs->node_name, child_name, parent_bs->node_name); 3169 return NULL; 3170 } 3171 3172 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm); 3173 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL, 3174 perm, shared_perm, &perm, &shared_perm); 3175 3176 return bdrv_attach_child_common(child_bs, child_name, child_class, 3177 child_role, perm, shared_perm, parent_bs, 3178 tran, errp); 3179 } 3180 3181 /* 3182 * This function steals the reference to child_bs from the caller. 3183 * That reference is later dropped by bdrv_root_unref_child(). 3184 * 3185 * On failure NULL is returned, errp is set and the reference to 3186 * child_bs is also dropped. 3187 * 3188 * The caller must hold the AioContext lock @child_bs, but not that of @ctx 3189 * (unless @child_bs is already in @ctx). 3190 */ 3191 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, 3192 const char *child_name, 3193 const BdrvChildClass *child_class, 3194 BdrvChildRole child_role, 3195 uint64_t perm, uint64_t shared_perm, 3196 void *opaque, Error **errp) 3197 { 3198 int ret; 3199 BdrvChild *child; 3200 Transaction *tran = tran_new(); 3201 3202 GLOBAL_STATE_CODE(); 3203 3204 child = bdrv_attach_child_common(child_bs, child_name, child_class, 3205 child_role, perm, shared_perm, opaque, 3206 tran, errp); 3207 if (!child) { 3208 ret = -EINVAL; 3209 goto out; 3210 } 3211 3212 ret = bdrv_refresh_perms(child_bs, tran, errp); 3213 3214 out: 3215 tran_finalize(tran, ret); 3216 3217 bdrv_schedule_unref(child_bs); 3218 3219 return ret < 0 ? NULL : child; 3220 } 3221 3222 /* 3223 * This function transfers the reference to child_bs from the caller 3224 * to parent_bs. That reference is later dropped by parent_bs on 3225 * bdrv_close() or if someone calls bdrv_unref_child(). 3226 * 3227 * On failure NULL is returned, errp is set and the reference to 3228 * child_bs is also dropped. 3229 * 3230 * If @parent_bs and @child_bs are in different AioContexts, the caller must 3231 * hold the AioContext lock for @child_bs, but not for @parent_bs. 3232 */ 3233 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, 3234 BlockDriverState *child_bs, 3235 const char *child_name, 3236 const BdrvChildClass *child_class, 3237 BdrvChildRole child_role, 3238 Error **errp) 3239 { 3240 int ret; 3241 BdrvChild *child; 3242 Transaction *tran = tran_new(); 3243 3244 GLOBAL_STATE_CODE(); 3245 3246 child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name, 3247 child_class, child_role, tran, errp); 3248 if (!child) { 3249 ret = -EINVAL; 3250 goto out; 3251 } 3252 3253 ret = bdrv_refresh_perms(parent_bs, tran, errp); 3254 if (ret < 0) { 3255 goto out; 3256 } 3257 3258 out: 3259 tran_finalize(tran, ret); 3260 3261 bdrv_schedule_unref(child_bs); 3262 3263 return ret < 0 ? NULL : child; 3264 } 3265 3266 /* Callers must ensure that child->frozen is false. */ 3267 void bdrv_root_unref_child(BdrvChild *child) 3268 { 3269 BlockDriverState *child_bs = child->bs; 3270 3271 GLOBAL_STATE_CODE(); 3272 bdrv_replace_child_noperm(child, NULL); 3273 bdrv_child_free(child); 3274 3275 if (child_bs) { 3276 /* 3277 * Update permissions for old node. We're just taking a parent away, so 3278 * we're loosening restrictions. Errors of permission update are not 3279 * fatal in this case, ignore them. 3280 */ 3281 bdrv_refresh_perms(child_bs, NULL, NULL); 3282 3283 /* 3284 * When the parent requiring a non-default AioContext is removed, the 3285 * node moves back to the main AioContext 3286 */ 3287 bdrv_try_change_aio_context(child_bs, qemu_get_aio_context(), NULL, 3288 NULL); 3289 } 3290 3291 bdrv_schedule_unref(child_bs); 3292 } 3293 3294 typedef struct BdrvSetInheritsFrom { 3295 BlockDriverState *bs; 3296 BlockDriverState *old_inherits_from; 3297 } BdrvSetInheritsFrom; 3298 3299 static void bdrv_set_inherits_from_abort(void *opaque) 3300 { 3301 BdrvSetInheritsFrom *s = opaque; 3302 3303 s->bs->inherits_from = s->old_inherits_from; 3304 } 3305 3306 static TransactionActionDrv bdrv_set_inherits_from_drv = { 3307 .abort = bdrv_set_inherits_from_abort, 3308 .clean = g_free, 3309 }; 3310 3311 /* @tran is allowed to be NULL. In this case no rollback is possible */ 3312 static void bdrv_set_inherits_from(BlockDriverState *bs, 3313 BlockDriverState *new_inherits_from, 3314 Transaction *tran) 3315 { 3316 if (tran) { 3317 BdrvSetInheritsFrom *s = g_new(BdrvSetInheritsFrom, 1); 3318 3319 *s = (BdrvSetInheritsFrom) { 3320 .bs = bs, 3321 .old_inherits_from = bs->inherits_from, 3322 }; 3323 3324 tran_add(tran, &bdrv_set_inherits_from_drv, s); 3325 } 3326 3327 bs->inherits_from = new_inherits_from; 3328 } 3329 3330 /** 3331 * Clear all inherits_from pointers from children and grandchildren of 3332 * @root that point to @root, where necessary. 3333 * @tran is allowed to be NULL. In this case no rollback is possible 3334 */ 3335 static void GRAPH_WRLOCK 3336 bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child, 3337 Transaction *tran) 3338 { 3339 BdrvChild *c; 3340 3341 if (child->bs->inherits_from == root) { 3342 /* 3343 * Remove inherits_from only when the last reference between root and 3344 * child->bs goes away. 3345 */ 3346 QLIST_FOREACH(c, &root->children, next) { 3347 if (c != child && c->bs == child->bs) { 3348 break; 3349 } 3350 } 3351 if (c == NULL) { 3352 bdrv_set_inherits_from(child->bs, NULL, tran); 3353 } 3354 } 3355 3356 QLIST_FOREACH(c, &child->bs->children, next) { 3357 bdrv_unset_inherits_from(root, c, tran); 3358 } 3359 } 3360 3361 /* Callers must ensure that child->frozen is false. */ 3362 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child) 3363 { 3364 GLOBAL_STATE_CODE(); 3365 if (child == NULL) { 3366 return; 3367 } 3368 3369 bdrv_unset_inherits_from(parent, child, NULL); 3370 bdrv_root_unref_child(child); 3371 } 3372 3373 3374 static void GRAPH_RDLOCK 3375 bdrv_parent_cb_change_media(BlockDriverState *bs, bool load) 3376 { 3377 BdrvChild *c; 3378 GLOBAL_STATE_CODE(); 3379 QLIST_FOREACH(c, &bs->parents, next_parent) { 3380 if (c->klass->change_media) { 3381 c->klass->change_media(c, load); 3382 } 3383 } 3384 } 3385 3386 /* Return true if you can reach parent going through child->inherits_from 3387 * recursively. If parent or child are NULL, return false */ 3388 static bool bdrv_inherits_from_recursive(BlockDriverState *child, 3389 BlockDriverState *parent) 3390 { 3391 while (child && child != parent) { 3392 child = child->inherits_from; 3393 } 3394 3395 return child != NULL; 3396 } 3397 3398 /* 3399 * Return the BdrvChildRole for @bs's backing child. bs->backing is 3400 * mostly used for COW backing children (role = COW), but also for 3401 * filtered children (role = FILTERED | PRIMARY). 3402 */ 3403 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs) 3404 { 3405 if (bs->drv && bs->drv->is_filter) { 3406 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY; 3407 } else { 3408 return BDRV_CHILD_COW; 3409 } 3410 } 3411 3412 /* 3413 * Sets the bs->backing or bs->file link of a BDS. A new reference is created; 3414 * callers which don't need their own reference any more must call bdrv_unref(). 3415 * 3416 * If the respective child is already present (i.e. we're detaching a node), 3417 * that child node must be drained. 3418 * 3419 * Function doesn't update permissions, caller is responsible for this. 3420 * 3421 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and 3422 * @child_bs can move to a different AioContext in this function. Callers must 3423 * make sure that their AioContext locking is still correct after this. 3424 * 3425 * After calling this function, the transaction @tran may only be completed 3426 * while holding a writer lock for the graph. 3427 */ 3428 static int GRAPH_WRLOCK 3429 bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs, 3430 BlockDriverState *child_bs, 3431 bool is_backing, 3432 Transaction *tran, Error **errp) 3433 { 3434 bool update_inherits_from = 3435 bdrv_inherits_from_recursive(child_bs, parent_bs); 3436 BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file; 3437 BdrvChildRole role; 3438 3439 GLOBAL_STATE_CODE(); 3440 3441 if (!parent_bs->drv) { 3442 /* 3443 * Node without drv is an object without a class :/. TODO: finally fix 3444 * qcow2 driver to never clear bs->drv and implement format corruption 3445 * handling in other way. 3446 */ 3447 error_setg(errp, "Node corrupted"); 3448 return -EINVAL; 3449 } 3450 3451 if (child && child->frozen) { 3452 error_setg(errp, "Cannot change frozen '%s' link from '%s' to '%s'", 3453 child->name, parent_bs->node_name, child->bs->node_name); 3454 return -EPERM; 3455 } 3456 3457 if (is_backing && !parent_bs->drv->is_filter && 3458 !parent_bs->drv->supports_backing) 3459 { 3460 error_setg(errp, "Driver '%s' of node '%s' does not support backing " 3461 "files", parent_bs->drv->format_name, parent_bs->node_name); 3462 return -EINVAL; 3463 } 3464 3465 if (parent_bs->drv->is_filter) { 3466 role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY; 3467 } else if (is_backing) { 3468 role = BDRV_CHILD_COW; 3469 } else { 3470 /* 3471 * We only can use same role as it is in existing child. We don't have 3472 * infrastructure to determine role of file child in generic way 3473 */ 3474 if (!child) { 3475 error_setg(errp, "Cannot set file child to format node without " 3476 "file child"); 3477 return -EINVAL; 3478 } 3479 role = child->role; 3480 } 3481 3482 if (child) { 3483 assert(child->bs->quiesce_counter); 3484 bdrv_unset_inherits_from(parent_bs, child, tran); 3485 bdrv_remove_child(child, tran); 3486 } 3487 3488 if (!child_bs) { 3489 goto out; 3490 } 3491 3492 child = bdrv_attach_child_noperm(parent_bs, child_bs, 3493 is_backing ? "backing" : "file", 3494 &child_of_bds, role, 3495 tran, errp); 3496 if (!child) { 3497 return -EINVAL; 3498 } 3499 3500 3501 /* 3502 * If inherits_from pointed recursively to bs then let's update it to 3503 * point directly to bs (else it will become NULL). 3504 */ 3505 if (update_inherits_from) { 3506 bdrv_set_inherits_from(child_bs, parent_bs, tran); 3507 } 3508 3509 out: 3510 bdrv_refresh_limits(parent_bs, tran, NULL); 3511 3512 return 0; 3513 } 3514 3515 /* 3516 * The caller must hold the AioContext lock for @backing_hd. Both @bs and 3517 * @backing_hd can move to a different AioContext in this function. Callers must 3518 * make sure that their AioContext locking is still correct after this. 3519 * 3520 * If a backing child is already present (i.e. we're detaching a node), that 3521 * child node must be drained. 3522 */ 3523 int bdrv_set_backing_hd_drained(BlockDriverState *bs, 3524 BlockDriverState *backing_hd, 3525 Error **errp) 3526 { 3527 int ret; 3528 Transaction *tran = tran_new(); 3529 3530 GLOBAL_STATE_CODE(); 3531 assert(bs->quiesce_counter > 0); 3532 if (bs->backing) { 3533 assert(bs->backing->bs->quiesce_counter > 0); 3534 } 3535 3536 ret = bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp); 3537 if (ret < 0) { 3538 goto out; 3539 } 3540 3541 ret = bdrv_refresh_perms(bs, tran, errp); 3542 out: 3543 tran_finalize(tran, ret); 3544 return ret; 3545 } 3546 3547 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, 3548 Error **errp) 3549 { 3550 BlockDriverState *drain_bs; 3551 int ret; 3552 GLOBAL_STATE_CODE(); 3553 3554 bdrv_graph_rdlock_main_loop(); 3555 drain_bs = bs->backing ? bs->backing->bs : bs; 3556 bdrv_graph_rdunlock_main_loop(); 3557 3558 bdrv_ref(drain_bs); 3559 bdrv_drained_begin(drain_bs); 3560 bdrv_graph_wrlock(); 3561 ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp); 3562 bdrv_graph_wrunlock(); 3563 bdrv_drained_end(drain_bs); 3564 bdrv_unref(drain_bs); 3565 3566 return ret; 3567 } 3568 3569 /* 3570 * Opens the backing file for a BlockDriverState if not yet open 3571 * 3572 * bdref_key specifies the key for the image's BlockdevRef in the options QDict. 3573 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 3574 * itself, all options starting with "${bdref_key}." are considered part of the 3575 * BlockdevRef. 3576 * 3577 * The caller must hold the main AioContext lock. 3578 * 3579 * TODO Can this be unified with bdrv_open_image()? 3580 */ 3581 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, 3582 const char *bdref_key, Error **errp) 3583 { 3584 char *backing_filename = NULL; 3585 char *bdref_key_dot; 3586 const char *reference = NULL; 3587 int ret = 0; 3588 bool implicit_backing = false; 3589 BlockDriverState *backing_hd; 3590 QDict *options; 3591 QDict *tmp_parent_options = NULL; 3592 Error *local_err = NULL; 3593 3594 GLOBAL_STATE_CODE(); 3595 GRAPH_RDLOCK_GUARD_MAINLOOP(); 3596 3597 if (bs->backing != NULL) { 3598 goto free_exit; 3599 } 3600 3601 /* NULL means an empty set of options */ 3602 if (parent_options == NULL) { 3603 tmp_parent_options = qdict_new(); 3604 parent_options = tmp_parent_options; 3605 } 3606 3607 bs->open_flags &= ~BDRV_O_NO_BACKING; 3608 3609 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 3610 qdict_extract_subqdict(parent_options, &options, bdref_key_dot); 3611 g_free(bdref_key_dot); 3612 3613 /* 3614 * Caution: while qdict_get_try_str() is fine, getting non-string 3615 * types would require more care. When @parent_options come from 3616 * -blockdev or blockdev_add, its members are typed according to 3617 * the QAPI schema, but when they come from -drive, they're all 3618 * QString. 3619 */ 3620 reference = qdict_get_try_str(parent_options, bdref_key); 3621 if (reference || qdict_haskey(options, "file.filename")) { 3622 /* keep backing_filename NULL */ 3623 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { 3624 qobject_unref(options); 3625 goto free_exit; 3626 } else { 3627 if (qdict_size(options) == 0) { 3628 /* If the user specifies options that do not modify the 3629 * backing file's behavior, we might still consider it the 3630 * implicit backing file. But it's easier this way, and 3631 * just specifying some of the backing BDS's options is 3632 * only possible with -drive anyway (otherwise the QAPI 3633 * schema forces the user to specify everything). */ 3634 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file); 3635 } 3636 3637 backing_filename = bdrv_get_full_backing_filename(bs, &local_err); 3638 if (local_err) { 3639 ret = -EINVAL; 3640 error_propagate(errp, local_err); 3641 qobject_unref(options); 3642 goto free_exit; 3643 } 3644 } 3645 3646 if (!bs->drv || !bs->drv->supports_backing) { 3647 ret = -EINVAL; 3648 error_setg(errp, "Driver doesn't support backing files"); 3649 qobject_unref(options); 3650 goto free_exit; 3651 } 3652 3653 if (!reference && 3654 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) { 3655 qdict_put_str(options, "driver", bs->backing_format); 3656 } 3657 3658 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs, 3659 &child_of_bds, bdrv_backing_role(bs), errp); 3660 if (!backing_hd) { 3661 bs->open_flags |= BDRV_O_NO_BACKING; 3662 error_prepend(errp, "Could not open backing file: "); 3663 ret = -EINVAL; 3664 goto free_exit; 3665 } 3666 3667 if (implicit_backing) { 3668 bdrv_refresh_filename(backing_hd); 3669 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 3670 backing_hd->filename); 3671 } 3672 3673 /* Hook up the backing file link; drop our reference, bs owns the 3674 * backing_hd reference now */ 3675 ret = bdrv_set_backing_hd(bs, backing_hd, errp); 3676 bdrv_unref(backing_hd); 3677 3678 if (ret < 0) { 3679 goto free_exit; 3680 } 3681 3682 qdict_del(parent_options, bdref_key); 3683 3684 free_exit: 3685 g_free(backing_filename); 3686 qobject_unref(tmp_parent_options); 3687 return ret; 3688 } 3689 3690 static BlockDriverState * 3691 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key, 3692 BlockDriverState *parent, const BdrvChildClass *child_class, 3693 BdrvChildRole child_role, bool allow_none, Error **errp) 3694 { 3695 BlockDriverState *bs = NULL; 3696 QDict *image_options; 3697 char *bdref_key_dot; 3698 const char *reference; 3699 3700 assert(child_class != NULL); 3701 3702 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 3703 qdict_extract_subqdict(options, &image_options, bdref_key_dot); 3704 g_free(bdref_key_dot); 3705 3706 /* 3707 * Caution: while qdict_get_try_str() is fine, getting non-string 3708 * types would require more care. When @options come from 3709 * -blockdev or blockdev_add, its members are typed according to 3710 * the QAPI schema, but when they come from -drive, they're all 3711 * QString. 3712 */ 3713 reference = qdict_get_try_str(options, bdref_key); 3714 if (!filename && !reference && !qdict_size(image_options)) { 3715 if (!allow_none) { 3716 error_setg(errp, "A block device must be specified for \"%s\"", 3717 bdref_key); 3718 } 3719 qobject_unref(image_options); 3720 goto done; 3721 } 3722 3723 bs = bdrv_open_inherit(filename, reference, image_options, 0, 3724 parent, child_class, child_role, errp); 3725 if (!bs) { 3726 goto done; 3727 } 3728 3729 done: 3730 qdict_del(options, bdref_key); 3731 return bs; 3732 } 3733 3734 /* 3735 * Opens a disk image whose options are given as BlockdevRef in another block 3736 * device's options. 3737 * 3738 * If allow_none is true, no image will be opened if filename is false and no 3739 * BlockdevRef is given. NULL will be returned, but errp remains unset. 3740 * 3741 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict. 3742 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 3743 * itself, all options starting with "${bdref_key}." are considered part of the 3744 * BlockdevRef. 3745 * 3746 * The BlockdevRef will be removed from the options QDict. 3747 * 3748 * The caller must hold the lock of the main AioContext and no other AioContext. 3749 * @parent can move to a different AioContext in this function. Callers must 3750 * make sure that their AioContext locking is still correct after this. 3751 */ 3752 BdrvChild *bdrv_open_child(const char *filename, 3753 QDict *options, const char *bdref_key, 3754 BlockDriverState *parent, 3755 const BdrvChildClass *child_class, 3756 BdrvChildRole child_role, 3757 bool allow_none, Error **errp) 3758 { 3759 BlockDriverState *bs; 3760 BdrvChild *child; 3761 3762 GLOBAL_STATE_CODE(); 3763 3764 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class, 3765 child_role, allow_none, errp); 3766 if (bs == NULL) { 3767 return NULL; 3768 } 3769 3770 bdrv_graph_wrlock(); 3771 child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role, 3772 errp); 3773 bdrv_graph_wrunlock(); 3774 3775 return child; 3776 } 3777 3778 /* 3779 * Wrapper on bdrv_open_child() for most popular case: open primary child of bs. 3780 * 3781 * The caller must hold the lock of the main AioContext and no other AioContext. 3782 * @parent can move to a different AioContext in this function. Callers must 3783 * make sure that their AioContext locking is still correct after this. 3784 */ 3785 int bdrv_open_file_child(const char *filename, 3786 QDict *options, const char *bdref_key, 3787 BlockDriverState *parent, Error **errp) 3788 { 3789 BdrvChildRole role; 3790 3791 /* commit_top and mirror_top don't use this function */ 3792 assert(!parent->drv->filtered_child_is_backing); 3793 role = parent->drv->is_filter ? 3794 (BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE; 3795 3796 if (!bdrv_open_child(filename, options, bdref_key, parent, 3797 &child_of_bds, role, false, errp)) 3798 { 3799 return -EINVAL; 3800 } 3801 3802 return 0; 3803 } 3804 3805 /* 3806 * TODO Future callers may need to specify parent/child_class in order for 3807 * option inheritance to work. Existing callers use it for the root node. 3808 */ 3809 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp) 3810 { 3811 BlockDriverState *bs = NULL; 3812 QObject *obj = NULL; 3813 QDict *qdict = NULL; 3814 const char *reference = NULL; 3815 Visitor *v = NULL; 3816 3817 GLOBAL_STATE_CODE(); 3818 3819 if (ref->type == QTYPE_QSTRING) { 3820 reference = ref->u.reference; 3821 } else { 3822 BlockdevOptions *options = &ref->u.definition; 3823 assert(ref->type == QTYPE_QDICT); 3824 3825 v = qobject_output_visitor_new(&obj); 3826 visit_type_BlockdevOptions(v, NULL, &options, &error_abort); 3827 visit_complete(v, &obj); 3828 3829 qdict = qobject_to(QDict, obj); 3830 qdict_flatten(qdict); 3831 3832 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for 3833 * compatibility with other callers) rather than what we want as the 3834 * real defaults. Apply the defaults here instead. */ 3835 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off"); 3836 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off"); 3837 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off"); 3838 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off"); 3839 3840 } 3841 3842 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp); 3843 obj = NULL; 3844 qobject_unref(obj); 3845 visit_free(v); 3846 return bs; 3847 } 3848 3849 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, 3850 int flags, 3851 QDict *snapshot_options, 3852 Error **errp) 3853 { 3854 g_autofree char *tmp_filename = NULL; 3855 int64_t total_size; 3856 QemuOpts *opts = NULL; 3857 BlockDriverState *bs_snapshot = NULL; 3858 int ret; 3859 3860 GLOBAL_STATE_CODE(); 3861 3862 /* if snapshot, we create a temporary backing file and open it 3863 instead of opening 'filename' directly */ 3864 3865 /* Get the required size from the image */ 3866 total_size = bdrv_getlength(bs); 3867 3868 if (total_size < 0) { 3869 error_setg_errno(errp, -total_size, "Could not get image size"); 3870 goto out; 3871 } 3872 3873 /* Create the temporary image */ 3874 tmp_filename = create_tmp_file(errp); 3875 if (!tmp_filename) { 3876 goto out; 3877 } 3878 3879 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0, 3880 &error_abort); 3881 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort); 3882 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp); 3883 qemu_opts_del(opts); 3884 if (ret < 0) { 3885 error_prepend(errp, "Could not create temporary overlay '%s': ", 3886 tmp_filename); 3887 goto out; 3888 } 3889 3890 /* Prepare options QDict for the temporary file */ 3891 qdict_put_str(snapshot_options, "file.driver", "file"); 3892 qdict_put_str(snapshot_options, "file.filename", tmp_filename); 3893 qdict_put_str(snapshot_options, "driver", "qcow2"); 3894 3895 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp); 3896 snapshot_options = NULL; 3897 if (!bs_snapshot) { 3898 goto out; 3899 } 3900 3901 ret = bdrv_append(bs_snapshot, bs, errp); 3902 if (ret < 0) { 3903 bs_snapshot = NULL; 3904 goto out; 3905 } 3906 3907 out: 3908 qobject_unref(snapshot_options); 3909 return bs_snapshot; 3910 } 3911 3912 /* 3913 * Opens a disk image (raw, qcow2, vmdk, ...) 3914 * 3915 * options is a QDict of options to pass to the block drivers, or NULL for an 3916 * empty set of options. The reference to the QDict belongs to the block layer 3917 * after the call (even on failure), so if the caller intends to reuse the 3918 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 3919 * 3920 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there. 3921 * If it is not NULL, the referenced BDS will be reused. 3922 * 3923 * The reference parameter may be used to specify an existing block device which 3924 * should be opened. If specified, neither options nor a filename may be given, 3925 * nor can an existing BDS be reused (that is, *pbs has to be NULL). 3926 * 3927 * The caller must always hold the main AioContext lock. 3928 */ 3929 static BlockDriverState * no_coroutine_fn 3930 bdrv_open_inherit(const char *filename, const char *reference, QDict *options, 3931 int flags, BlockDriverState *parent, 3932 const BdrvChildClass *child_class, BdrvChildRole child_role, 3933 Error **errp) 3934 { 3935 int ret; 3936 BlockBackend *file = NULL; 3937 BlockDriverState *bs; 3938 BlockDriver *drv = NULL; 3939 BdrvChild *child; 3940 const char *drvname; 3941 const char *backing; 3942 Error *local_err = NULL; 3943 QDict *snapshot_options = NULL; 3944 int snapshot_flags = 0; 3945 3946 assert(!child_class || !flags); 3947 assert(!child_class == !parent); 3948 GLOBAL_STATE_CODE(); 3949 assert(!qemu_in_coroutine()); 3950 3951 /* TODO We'll eventually have to take a writer lock in this function */ 3952 GRAPH_RDLOCK_GUARD_MAINLOOP(); 3953 3954 if (reference) { 3955 bool options_non_empty = options ? qdict_size(options) : false; 3956 qobject_unref(options); 3957 3958 if (filename || options_non_empty) { 3959 error_setg(errp, "Cannot reference an existing block device with " 3960 "additional options or a new filename"); 3961 return NULL; 3962 } 3963 3964 bs = bdrv_lookup_bs(reference, reference, errp); 3965 if (!bs) { 3966 return NULL; 3967 } 3968 3969 bdrv_ref(bs); 3970 return bs; 3971 } 3972 3973 bs = bdrv_new(); 3974 3975 /* NULL means an empty set of options */ 3976 if (options == NULL) { 3977 options = qdict_new(); 3978 } 3979 3980 /* json: syntax counts as explicit options, as if in the QDict */ 3981 parse_json_protocol(options, &filename, &local_err); 3982 if (local_err) { 3983 goto fail; 3984 } 3985 3986 bs->explicit_options = qdict_clone_shallow(options); 3987 3988 if (child_class) { 3989 bool parent_is_format; 3990 3991 if (parent->drv) { 3992 parent_is_format = parent->drv->is_format; 3993 } else { 3994 /* 3995 * parent->drv is not set yet because this node is opened for 3996 * (potential) format probing. That means that @parent is going 3997 * to be a format node. 3998 */ 3999 parent_is_format = true; 4000 } 4001 4002 bs->inherits_from = parent; 4003 child_class->inherit_options(child_role, parent_is_format, 4004 &flags, options, 4005 parent->open_flags, parent->options); 4006 } 4007 4008 ret = bdrv_fill_options(&options, filename, &flags, &local_err); 4009 if (ret < 0) { 4010 goto fail; 4011 } 4012 4013 /* 4014 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags. 4015 * Caution: getting a boolean member of @options requires care. 4016 * When @options come from -blockdev or blockdev_add, members are 4017 * typed according to the QAPI schema, but when they come from 4018 * -drive, they're all QString. 4019 */ 4020 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") && 4021 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) { 4022 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR); 4023 } else { 4024 flags &= ~BDRV_O_RDWR; 4025 } 4026 4027 if (flags & BDRV_O_SNAPSHOT) { 4028 snapshot_options = qdict_new(); 4029 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options, 4030 flags, options); 4031 /* Let bdrv_backing_options() override "read-only" */ 4032 qdict_del(options, BDRV_OPT_READ_ONLY); 4033 bdrv_inherited_options(BDRV_CHILD_COW, true, 4034 &flags, options, flags, options); 4035 } 4036 4037 bs->open_flags = flags; 4038 bs->options = options; 4039 options = qdict_clone_shallow(options); 4040 4041 /* Find the right image format driver */ 4042 /* See cautionary note on accessing @options above */ 4043 drvname = qdict_get_try_str(options, "driver"); 4044 if (drvname) { 4045 drv = bdrv_find_format(drvname); 4046 if (!drv) { 4047 error_setg(errp, "Unknown driver: '%s'", drvname); 4048 goto fail; 4049 } 4050 } 4051 4052 assert(drvname || !(flags & BDRV_O_PROTOCOL)); 4053 4054 /* See cautionary note on accessing @options above */ 4055 backing = qdict_get_try_str(options, "backing"); 4056 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL || 4057 (backing && *backing == '\0')) 4058 { 4059 if (backing) { 4060 warn_report("Use of \"backing\": \"\" is deprecated; " 4061 "use \"backing\": null instead"); 4062 } 4063 flags |= BDRV_O_NO_BACKING; 4064 qdict_del(bs->explicit_options, "backing"); 4065 qdict_del(bs->options, "backing"); 4066 qdict_del(options, "backing"); 4067 } 4068 4069 /* Open image file without format layer. This BlockBackend is only used for 4070 * probing, the block drivers will do their own bdrv_open_child() for the 4071 * same BDS, which is why we put the node name back into options. */ 4072 if ((flags & BDRV_O_PROTOCOL) == 0) { 4073 BlockDriverState *file_bs; 4074 4075 file_bs = bdrv_open_child_bs(filename, options, "file", bs, 4076 &child_of_bds, BDRV_CHILD_IMAGE, 4077 true, &local_err); 4078 if (local_err) { 4079 goto fail; 4080 } 4081 if (file_bs != NULL) { 4082 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only 4083 * looking at the header to guess the image format. This works even 4084 * in cases where a guest would not see a consistent state. */ 4085 AioContext *ctx = bdrv_get_aio_context(file_bs); 4086 file = blk_new(ctx, 0, BLK_PERM_ALL); 4087 blk_insert_bs(file, file_bs, &local_err); 4088 bdrv_unref(file_bs); 4089 4090 if (local_err) { 4091 goto fail; 4092 } 4093 4094 qdict_put_str(options, "file", bdrv_get_node_name(file_bs)); 4095 } 4096 } 4097 4098 /* Image format probing */ 4099 bs->probed = !drv; 4100 if (!drv && file) { 4101 ret = find_image_format(file, filename, &drv, &local_err); 4102 if (ret < 0) { 4103 goto fail; 4104 } 4105 /* 4106 * This option update would logically belong in bdrv_fill_options(), 4107 * but we first need to open bs->file for the probing to work, while 4108 * opening bs->file already requires the (mostly) final set of options 4109 * so that cache mode etc. can be inherited. 4110 * 4111 * Adding the driver later is somewhat ugly, but it's not an option 4112 * that would ever be inherited, so it's correct. We just need to make 4113 * sure to update both bs->options (which has the full effective 4114 * options for bs) and options (which has file.* already removed). 4115 */ 4116 qdict_put_str(bs->options, "driver", drv->format_name); 4117 qdict_put_str(options, "driver", drv->format_name); 4118 } else if (!drv) { 4119 error_setg(errp, "Must specify either driver or file"); 4120 goto fail; 4121 } 4122 4123 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */ 4124 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open); 4125 /* file must be NULL if a protocol BDS is about to be created 4126 * (the inverse results in an error message from bdrv_open_common()) */ 4127 assert(!(flags & BDRV_O_PROTOCOL) || !file); 4128 4129 /* Open the image */ 4130 ret = bdrv_open_common(bs, file, options, &local_err); 4131 if (ret < 0) { 4132 goto fail; 4133 } 4134 4135 if (file) { 4136 blk_unref(file); 4137 file = NULL; 4138 } 4139 4140 /* If there is a backing file, use it */ 4141 if ((flags & BDRV_O_NO_BACKING) == 0) { 4142 ret = bdrv_open_backing_file(bs, options, "backing", &local_err); 4143 if (ret < 0) { 4144 goto close_and_fail; 4145 } 4146 } 4147 4148 /* Remove all children options and references 4149 * from bs->options and bs->explicit_options */ 4150 QLIST_FOREACH(child, &bs->children, next) { 4151 char *child_key_dot; 4152 child_key_dot = g_strdup_printf("%s.", child->name); 4153 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot); 4154 qdict_extract_subqdict(bs->options, NULL, child_key_dot); 4155 qdict_del(bs->explicit_options, child->name); 4156 qdict_del(bs->options, child->name); 4157 g_free(child_key_dot); 4158 } 4159 4160 /* Check if any unknown options were used */ 4161 if (qdict_size(options) != 0) { 4162 const QDictEntry *entry = qdict_first(options); 4163 if (flags & BDRV_O_PROTOCOL) { 4164 error_setg(errp, "Block protocol '%s' doesn't support the option " 4165 "'%s'", drv->format_name, entry->key); 4166 } else { 4167 error_setg(errp, 4168 "Block format '%s' does not support the option '%s'", 4169 drv->format_name, entry->key); 4170 } 4171 4172 goto close_and_fail; 4173 } 4174 4175 bdrv_parent_cb_change_media(bs, true); 4176 4177 qobject_unref(options); 4178 options = NULL; 4179 4180 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the 4181 * temporary snapshot afterwards. */ 4182 if (snapshot_flags) { 4183 BlockDriverState *snapshot_bs; 4184 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags, 4185 snapshot_options, &local_err); 4186 snapshot_options = NULL; 4187 if (local_err) { 4188 goto close_and_fail; 4189 } 4190 /* We are not going to return bs but the overlay on top of it 4191 * (snapshot_bs); thus, we have to drop the strong reference to bs 4192 * (which we obtained by calling bdrv_new()). bs will not be deleted, 4193 * though, because the overlay still has a reference to it. */ 4194 bdrv_unref(bs); 4195 bs = snapshot_bs; 4196 } 4197 4198 return bs; 4199 4200 fail: 4201 blk_unref(file); 4202 qobject_unref(snapshot_options); 4203 qobject_unref(bs->explicit_options); 4204 qobject_unref(bs->options); 4205 qobject_unref(options); 4206 bs->options = NULL; 4207 bs->explicit_options = NULL; 4208 bdrv_unref(bs); 4209 error_propagate(errp, local_err); 4210 return NULL; 4211 4212 close_and_fail: 4213 bdrv_unref(bs); 4214 qobject_unref(snapshot_options); 4215 qobject_unref(options); 4216 error_propagate(errp, local_err); 4217 return NULL; 4218 } 4219 4220 /* The caller must always hold the main AioContext lock. */ 4221 BlockDriverState *bdrv_open(const char *filename, const char *reference, 4222 QDict *options, int flags, Error **errp) 4223 { 4224 GLOBAL_STATE_CODE(); 4225 4226 return bdrv_open_inherit(filename, reference, options, flags, NULL, 4227 NULL, 0, errp); 4228 } 4229 4230 /* Return true if the NULL-terminated @list contains @str */ 4231 static bool is_str_in_list(const char *str, const char *const *list) 4232 { 4233 if (str && list) { 4234 int i; 4235 for (i = 0; list[i] != NULL; i++) { 4236 if (!strcmp(str, list[i])) { 4237 return true; 4238 } 4239 } 4240 } 4241 return false; 4242 } 4243 4244 /* 4245 * Check that every option set in @bs->options is also set in 4246 * @new_opts. 4247 * 4248 * Options listed in the common_options list and in 4249 * @bs->drv->mutable_opts are skipped. 4250 * 4251 * Return 0 on success, otherwise return -EINVAL and set @errp. 4252 */ 4253 static int bdrv_reset_options_allowed(BlockDriverState *bs, 4254 const QDict *new_opts, Error **errp) 4255 { 4256 const QDictEntry *e; 4257 /* These options are common to all block drivers and are handled 4258 * in bdrv_reopen_prepare() so they can be left out of @new_opts */ 4259 const char *const common_options[] = { 4260 "node-name", "discard", "cache.direct", "cache.no-flush", 4261 "read-only", "auto-read-only", "detect-zeroes", NULL 4262 }; 4263 4264 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) { 4265 if (!qdict_haskey(new_opts, e->key) && 4266 !is_str_in_list(e->key, common_options) && 4267 !is_str_in_list(e->key, bs->drv->mutable_opts)) { 4268 error_setg(errp, "Option '%s' cannot be reset " 4269 "to its default value", e->key); 4270 return -EINVAL; 4271 } 4272 } 4273 4274 return 0; 4275 } 4276 4277 /* 4278 * Returns true if @child can be reached recursively from @bs 4279 */ 4280 static bool GRAPH_RDLOCK 4281 bdrv_recurse_has_child(BlockDriverState *bs, BlockDriverState *child) 4282 { 4283 BdrvChild *c; 4284 4285 if (bs == child) { 4286 return true; 4287 } 4288 4289 QLIST_FOREACH(c, &bs->children, next) { 4290 if (bdrv_recurse_has_child(c->bs, child)) { 4291 return true; 4292 } 4293 } 4294 4295 return false; 4296 } 4297 4298 /* 4299 * Adds a BlockDriverState to a simple queue for an atomic, transactional 4300 * reopen of multiple devices. 4301 * 4302 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT 4303 * already performed, or alternatively may be NULL a new BlockReopenQueue will 4304 * be created and initialized. This newly created BlockReopenQueue should be 4305 * passed back in for subsequent calls that are intended to be of the same 4306 * atomic 'set'. 4307 * 4308 * bs is the BlockDriverState to add to the reopen queue. 4309 * 4310 * options contains the changed options for the associated bs 4311 * (the BlockReopenQueue takes ownership) 4312 * 4313 * flags contains the open flags for the associated bs 4314 * 4315 * returns a pointer to bs_queue, which is either the newly allocated 4316 * bs_queue, or the existing bs_queue being used. 4317 * 4318 * bs is drained here and undrained by bdrv_reopen_queue_free(). 4319 * 4320 * To be called with bs->aio_context locked. 4321 */ 4322 static BlockReopenQueue * GRAPH_RDLOCK 4323 bdrv_reopen_queue_child(BlockReopenQueue *bs_queue, BlockDriverState *bs, 4324 QDict *options, const BdrvChildClass *klass, 4325 BdrvChildRole role, bool parent_is_format, 4326 QDict *parent_options, int parent_flags, 4327 bool keep_old_opts) 4328 { 4329 assert(bs != NULL); 4330 4331 BlockReopenQueueEntry *bs_entry; 4332 BdrvChild *child; 4333 QDict *old_options, *explicit_options, *options_copy; 4334 int flags; 4335 QemuOpts *opts; 4336 4337 GLOBAL_STATE_CODE(); 4338 4339 /* 4340 * Strictly speaking, draining is illegal under GRAPH_RDLOCK. We know that 4341 * we've been called with bdrv_graph_rdlock_main_loop(), though, so it's ok 4342 * in practice. 4343 */ 4344 bdrv_drained_begin(bs); 4345 4346 if (bs_queue == NULL) { 4347 bs_queue = g_new0(BlockReopenQueue, 1); 4348 QTAILQ_INIT(bs_queue); 4349 } 4350 4351 if (!options) { 4352 options = qdict_new(); 4353 } 4354 4355 /* Check if this BlockDriverState is already in the queue */ 4356 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4357 if (bs == bs_entry->state.bs) { 4358 break; 4359 } 4360 } 4361 4362 /* 4363 * Precedence of options: 4364 * 1. Explicitly passed in options (highest) 4365 * 2. Retained from explicitly set options of bs 4366 * 3. Inherited from parent node 4367 * 4. Retained from effective options of bs 4368 */ 4369 4370 /* Old explicitly set values (don't overwrite by inherited value) */ 4371 if (bs_entry || keep_old_opts) { 4372 old_options = qdict_clone_shallow(bs_entry ? 4373 bs_entry->state.explicit_options : 4374 bs->explicit_options); 4375 bdrv_join_options(bs, options, old_options); 4376 qobject_unref(old_options); 4377 } 4378 4379 explicit_options = qdict_clone_shallow(options); 4380 4381 /* Inherit from parent node */ 4382 if (parent_options) { 4383 flags = 0; 4384 klass->inherit_options(role, parent_is_format, &flags, options, 4385 parent_flags, parent_options); 4386 } else { 4387 flags = bdrv_get_flags(bs); 4388 } 4389 4390 if (keep_old_opts) { 4391 /* Old values are used for options that aren't set yet */ 4392 old_options = qdict_clone_shallow(bs->options); 4393 bdrv_join_options(bs, options, old_options); 4394 qobject_unref(old_options); 4395 } 4396 4397 /* We have the final set of options so let's update the flags */ 4398 options_copy = qdict_clone_shallow(options); 4399 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 4400 qemu_opts_absorb_qdict(opts, options_copy, NULL); 4401 update_flags_from_options(&flags, opts); 4402 qemu_opts_del(opts); 4403 qobject_unref(options_copy); 4404 4405 /* bdrv_open_inherit() sets and clears some additional flags internally */ 4406 flags &= ~BDRV_O_PROTOCOL; 4407 if (flags & BDRV_O_RDWR) { 4408 flags |= BDRV_O_ALLOW_RDWR; 4409 } 4410 4411 if (!bs_entry) { 4412 bs_entry = g_new0(BlockReopenQueueEntry, 1); 4413 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry); 4414 } else { 4415 qobject_unref(bs_entry->state.options); 4416 qobject_unref(bs_entry->state.explicit_options); 4417 } 4418 4419 bs_entry->state.bs = bs; 4420 bs_entry->state.options = options; 4421 bs_entry->state.explicit_options = explicit_options; 4422 bs_entry->state.flags = flags; 4423 4424 /* 4425 * If keep_old_opts is false then it means that unspecified 4426 * options must be reset to their original value. We don't allow 4427 * resetting 'backing' but we need to know if the option is 4428 * missing in order to decide if we have to return an error. 4429 */ 4430 if (!keep_old_opts) { 4431 bs_entry->state.backing_missing = 4432 !qdict_haskey(options, "backing") && 4433 !qdict_haskey(options, "backing.driver"); 4434 } 4435 4436 QLIST_FOREACH(child, &bs->children, next) { 4437 QDict *new_child_options = NULL; 4438 bool child_keep_old = keep_old_opts; 4439 4440 /* reopen can only change the options of block devices that were 4441 * implicitly created and inherited options. For other (referenced) 4442 * block devices, a syntax like "backing.foo" results in an error. */ 4443 if (child->bs->inherits_from != bs) { 4444 continue; 4445 } 4446 4447 /* Check if the options contain a child reference */ 4448 if (qdict_haskey(options, child->name)) { 4449 const char *childref = qdict_get_try_str(options, child->name); 4450 /* 4451 * The current child must not be reopened if the child 4452 * reference is null or points to a different node. 4453 */ 4454 if (g_strcmp0(childref, child->bs->node_name)) { 4455 continue; 4456 } 4457 /* 4458 * If the child reference points to the current child then 4459 * reopen it with its existing set of options (note that 4460 * it can still inherit new options from the parent). 4461 */ 4462 child_keep_old = true; 4463 } else { 4464 /* Extract child options ("child-name.*") */ 4465 char *child_key_dot = g_strdup_printf("%s.", child->name); 4466 qdict_extract_subqdict(explicit_options, NULL, child_key_dot); 4467 qdict_extract_subqdict(options, &new_child_options, child_key_dot); 4468 g_free(child_key_dot); 4469 } 4470 4471 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options, 4472 child->klass, child->role, bs->drv->is_format, 4473 options, flags, child_keep_old); 4474 } 4475 4476 return bs_queue; 4477 } 4478 4479 /* To be called with bs->aio_context locked */ 4480 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue, 4481 BlockDriverState *bs, 4482 QDict *options, bool keep_old_opts) 4483 { 4484 GLOBAL_STATE_CODE(); 4485 GRAPH_RDLOCK_GUARD_MAINLOOP(); 4486 4487 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false, 4488 NULL, 0, keep_old_opts); 4489 } 4490 4491 void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue) 4492 { 4493 GLOBAL_STATE_CODE(); 4494 if (bs_queue) { 4495 BlockReopenQueueEntry *bs_entry, *next; 4496 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 4497 bdrv_drained_end(bs_entry->state.bs); 4498 qobject_unref(bs_entry->state.explicit_options); 4499 qobject_unref(bs_entry->state.options); 4500 g_free(bs_entry); 4501 } 4502 g_free(bs_queue); 4503 } 4504 } 4505 4506 /* 4507 * Reopen multiple BlockDriverStates atomically & transactionally. 4508 * 4509 * The queue passed in (bs_queue) must have been built up previous 4510 * via bdrv_reopen_queue(). 4511 * 4512 * Reopens all BDS specified in the queue, with the appropriate 4513 * flags. All devices are prepared for reopen, and failure of any 4514 * device will cause all device changes to be abandoned, and intermediate 4515 * data cleaned up. 4516 * 4517 * If all devices prepare successfully, then the changes are committed 4518 * to all devices. 4519 * 4520 * All affected nodes must be drained between bdrv_reopen_queue() and 4521 * bdrv_reopen_multiple(). 4522 * 4523 * To be called from the main thread, with all other AioContexts unlocked. 4524 */ 4525 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) 4526 { 4527 int ret = -1; 4528 BlockReopenQueueEntry *bs_entry, *next; 4529 Transaction *tran = tran_new(); 4530 g_autoptr(GSList) refresh_list = NULL; 4531 4532 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 4533 assert(bs_queue != NULL); 4534 GLOBAL_STATE_CODE(); 4535 4536 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4537 ret = bdrv_flush(bs_entry->state.bs); 4538 if (ret < 0) { 4539 error_setg_errno(errp, -ret, "Error flushing drive"); 4540 goto abort; 4541 } 4542 } 4543 4544 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4545 assert(bs_entry->state.bs->quiesce_counter > 0); 4546 ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp); 4547 if (ret < 0) { 4548 goto abort; 4549 } 4550 bs_entry->prepared = true; 4551 } 4552 4553 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4554 BDRVReopenState *state = &bs_entry->state; 4555 4556 refresh_list = g_slist_prepend(refresh_list, state->bs); 4557 if (state->old_backing_bs) { 4558 refresh_list = g_slist_prepend(refresh_list, state->old_backing_bs); 4559 } 4560 if (state->old_file_bs) { 4561 refresh_list = g_slist_prepend(refresh_list, state->old_file_bs); 4562 } 4563 } 4564 4565 /* 4566 * Note that file-posix driver rely on permission update done during reopen 4567 * (even if no permission changed), because it wants "new" permissions for 4568 * reconfiguring the fd and that's why it does it in raw_check_perm(), not 4569 * in raw_reopen_prepare() which is called with "old" permissions. 4570 */ 4571 bdrv_graph_rdlock_main_loop(); 4572 ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp); 4573 bdrv_graph_rdunlock_main_loop(); 4574 4575 if (ret < 0) { 4576 goto abort; 4577 } 4578 4579 /* 4580 * If we reach this point, we have success and just need to apply the 4581 * changes. 4582 * 4583 * Reverse order is used to comfort qcow2 driver: on commit it need to write 4584 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But 4585 * children are usually goes after parents in reopen-queue, so go from last 4586 * to first element. 4587 */ 4588 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 4589 bdrv_reopen_commit(&bs_entry->state); 4590 } 4591 4592 bdrv_graph_wrlock(); 4593 tran_commit(tran); 4594 bdrv_graph_wrunlock(); 4595 4596 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 4597 BlockDriverState *bs = bs_entry->state.bs; 4598 4599 if (bs->drv->bdrv_reopen_commit_post) { 4600 bs->drv->bdrv_reopen_commit_post(&bs_entry->state); 4601 } 4602 } 4603 4604 ret = 0; 4605 goto cleanup; 4606 4607 abort: 4608 bdrv_graph_wrlock(); 4609 tran_abort(tran); 4610 bdrv_graph_wrunlock(); 4611 4612 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 4613 if (bs_entry->prepared) { 4614 bdrv_reopen_abort(&bs_entry->state); 4615 } 4616 } 4617 4618 cleanup: 4619 bdrv_reopen_queue_free(bs_queue); 4620 4621 return ret; 4622 } 4623 4624 int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts, 4625 Error **errp) 4626 { 4627 BlockReopenQueue *queue; 4628 4629 GLOBAL_STATE_CODE(); 4630 4631 queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts); 4632 4633 return bdrv_reopen_multiple(queue, errp); 4634 } 4635 4636 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only, 4637 Error **errp) 4638 { 4639 QDict *opts = qdict_new(); 4640 4641 GLOBAL_STATE_CODE(); 4642 4643 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only); 4644 4645 return bdrv_reopen(bs, opts, true, errp); 4646 } 4647 4648 /* 4649 * Take a BDRVReopenState and check if the value of 'backing' in the 4650 * reopen_state->options QDict is valid or not. 4651 * 4652 * If 'backing' is missing from the QDict then return 0. 4653 * 4654 * If 'backing' contains the node name of the backing file of 4655 * reopen_state->bs then return 0. 4656 * 4657 * If 'backing' contains a different node name (or is null) then check 4658 * whether the current backing file can be replaced with the new one. 4659 * If that's the case then reopen_state->replace_backing_bs is set to 4660 * true and reopen_state->new_backing_bs contains a pointer to the new 4661 * backing BlockDriverState (or NULL). 4662 * 4663 * After calling this function, the transaction @tran may only be completed 4664 * while holding a writer lock for the graph. 4665 * 4666 * Return 0 on success, otherwise return < 0 and set @errp. 4667 * 4668 * The caller must hold the AioContext lock of @reopen_state->bs. 4669 * @reopen_state->bs can move to a different AioContext in this function. 4670 * Callers must make sure that their AioContext locking is still correct after 4671 * this. 4672 */ 4673 static int GRAPH_UNLOCKED 4674 bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state, 4675 bool is_backing, Transaction *tran, 4676 Error **errp) 4677 { 4678 BlockDriverState *bs = reopen_state->bs; 4679 BlockDriverState *new_child_bs; 4680 BlockDriverState *old_child_bs; 4681 4682 const char *child_name = is_backing ? "backing" : "file"; 4683 QObject *value; 4684 const char *str; 4685 bool has_child; 4686 int ret; 4687 4688 GLOBAL_STATE_CODE(); 4689 4690 value = qdict_get(reopen_state->options, child_name); 4691 if (value == NULL) { 4692 return 0; 4693 } 4694 4695 bdrv_graph_rdlock_main_loop(); 4696 4697 switch (qobject_type(value)) { 4698 case QTYPE_QNULL: 4699 assert(is_backing); /* The 'file' option does not allow a null value */ 4700 new_child_bs = NULL; 4701 break; 4702 case QTYPE_QSTRING: 4703 str = qstring_get_str(qobject_to(QString, value)); 4704 new_child_bs = bdrv_lookup_bs(NULL, str, errp); 4705 if (new_child_bs == NULL) { 4706 ret = -EINVAL; 4707 goto out_rdlock; 4708 } 4709 4710 has_child = bdrv_recurse_has_child(new_child_bs, bs); 4711 if (has_child) { 4712 error_setg(errp, "Making '%s' a %s child of '%s' would create a " 4713 "cycle", str, child_name, bs->node_name); 4714 ret = -EINVAL; 4715 goto out_rdlock; 4716 } 4717 break; 4718 default: 4719 /* 4720 * The options QDict has been flattened, so 'backing' and 'file' 4721 * do not allow any other data type here. 4722 */ 4723 g_assert_not_reached(); 4724 } 4725 4726 old_child_bs = is_backing ? child_bs(bs->backing) : child_bs(bs->file); 4727 if (old_child_bs == new_child_bs) { 4728 ret = 0; 4729 goto out_rdlock; 4730 } 4731 4732 if (old_child_bs) { 4733 if (bdrv_skip_implicit_filters(old_child_bs) == new_child_bs) { 4734 ret = 0; 4735 goto out_rdlock; 4736 } 4737 4738 if (old_child_bs->implicit) { 4739 error_setg(errp, "Cannot replace implicit %s child of %s", 4740 child_name, bs->node_name); 4741 ret = -EPERM; 4742 goto out_rdlock; 4743 } 4744 } 4745 4746 if (bs->drv->is_filter && !old_child_bs) { 4747 /* 4748 * Filters always have a file or a backing child, so we are trying to 4749 * change wrong child 4750 */ 4751 error_setg(errp, "'%s' is a %s filter node that does not support a " 4752 "%s child", bs->node_name, bs->drv->format_name, child_name); 4753 ret = -EINVAL; 4754 goto out_rdlock; 4755 } 4756 4757 if (is_backing) { 4758 reopen_state->old_backing_bs = old_child_bs; 4759 } else { 4760 reopen_state->old_file_bs = old_child_bs; 4761 } 4762 4763 if (old_child_bs) { 4764 bdrv_ref(old_child_bs); 4765 bdrv_drained_begin(old_child_bs); 4766 } 4767 4768 bdrv_graph_rdunlock_main_loop(); 4769 bdrv_graph_wrlock(); 4770 4771 ret = bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing, 4772 tran, errp); 4773 4774 bdrv_graph_wrunlock(); 4775 4776 if (old_child_bs) { 4777 bdrv_drained_end(old_child_bs); 4778 bdrv_unref(old_child_bs); 4779 } 4780 4781 return ret; 4782 4783 out_rdlock: 4784 bdrv_graph_rdunlock_main_loop(); 4785 return ret; 4786 } 4787 4788 /* 4789 * Prepares a BlockDriverState for reopen. All changes are staged in the 4790 * 'opaque' field of the BDRVReopenState, which is used and allocated by 4791 * the block driver layer .bdrv_reopen_prepare() 4792 * 4793 * bs is the BlockDriverState to reopen 4794 * flags are the new open flags 4795 * queue is the reopen queue 4796 * 4797 * Returns 0 on success, non-zero on error. On error errp will be set 4798 * as well. 4799 * 4800 * On failure, bdrv_reopen_abort() will be called to clean up any data. 4801 * It is the responsibility of the caller to then call the abort() or 4802 * commit() for any other BDS that have been left in a prepare() state 4803 * 4804 * The caller must hold the AioContext lock of @reopen_state->bs. 4805 * 4806 * After calling this function, the transaction @change_child_tran may only be 4807 * completed while holding a writer lock for the graph. 4808 */ 4809 static int GRAPH_UNLOCKED 4810 bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, 4811 Transaction *change_child_tran, Error **errp) 4812 { 4813 int ret = -1; 4814 int old_flags; 4815 Error *local_err = NULL; 4816 BlockDriver *drv; 4817 QemuOpts *opts; 4818 QDict *orig_reopen_opts; 4819 char *discard = NULL; 4820 bool read_only; 4821 bool drv_prepared = false; 4822 4823 assert(reopen_state != NULL); 4824 assert(reopen_state->bs->drv != NULL); 4825 GLOBAL_STATE_CODE(); 4826 drv = reopen_state->bs->drv; 4827 4828 /* This function and each driver's bdrv_reopen_prepare() remove 4829 * entries from reopen_state->options as they are processed, so 4830 * we need to make a copy of the original QDict. */ 4831 orig_reopen_opts = qdict_clone_shallow(reopen_state->options); 4832 4833 /* Process generic block layer options */ 4834 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 4835 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) { 4836 ret = -EINVAL; 4837 goto error; 4838 } 4839 4840 /* This was already called in bdrv_reopen_queue_child() so the flags 4841 * are up-to-date. This time we simply want to remove the options from 4842 * QemuOpts in order to indicate that they have been processed. */ 4843 old_flags = reopen_state->flags; 4844 update_flags_from_options(&reopen_state->flags, opts); 4845 assert(old_flags == reopen_state->flags); 4846 4847 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD); 4848 if (discard != NULL) { 4849 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) { 4850 error_setg(errp, "Invalid discard option"); 4851 ret = -EINVAL; 4852 goto error; 4853 } 4854 } 4855 4856 reopen_state->detect_zeroes = 4857 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err); 4858 if (local_err) { 4859 error_propagate(errp, local_err); 4860 ret = -EINVAL; 4861 goto error; 4862 } 4863 4864 /* All other options (including node-name and driver) must be unchanged. 4865 * Put them back into the QDict, so that they are checked at the end 4866 * of this function. */ 4867 qemu_opts_to_qdict(opts, reopen_state->options); 4868 4869 /* If we are to stay read-only, do not allow permission change 4870 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is 4871 * not set, or if the BDS still has copy_on_read enabled */ 4872 read_only = !(reopen_state->flags & BDRV_O_RDWR); 4873 4874 bdrv_graph_rdlock_main_loop(); 4875 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err); 4876 bdrv_graph_rdunlock_main_loop(); 4877 if (local_err) { 4878 error_propagate(errp, local_err); 4879 goto error; 4880 } 4881 4882 if (drv->bdrv_reopen_prepare) { 4883 /* 4884 * If a driver-specific option is missing, it means that we 4885 * should reset it to its default value. 4886 * But not all options allow that, so we need to check it first. 4887 */ 4888 ret = bdrv_reset_options_allowed(reopen_state->bs, 4889 reopen_state->options, errp); 4890 if (ret) { 4891 goto error; 4892 } 4893 4894 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err); 4895 if (ret) { 4896 if (local_err != NULL) { 4897 error_propagate(errp, local_err); 4898 } else { 4899 bdrv_graph_rdlock_main_loop(); 4900 bdrv_refresh_filename(reopen_state->bs); 4901 bdrv_graph_rdunlock_main_loop(); 4902 error_setg(errp, "failed while preparing to reopen image '%s'", 4903 reopen_state->bs->filename); 4904 } 4905 goto error; 4906 } 4907 } else { 4908 /* It is currently mandatory to have a bdrv_reopen_prepare() 4909 * handler for each supported drv. */ 4910 bdrv_graph_rdlock_main_loop(); 4911 error_setg(errp, "Block format '%s' used by node '%s' " 4912 "does not support reopening files", drv->format_name, 4913 bdrv_get_device_or_node_name(reopen_state->bs)); 4914 bdrv_graph_rdunlock_main_loop(); 4915 ret = -1; 4916 goto error; 4917 } 4918 4919 drv_prepared = true; 4920 4921 /* 4922 * We must provide the 'backing' option if the BDS has a backing 4923 * file or if the image file has a backing file name as part of 4924 * its metadata. Otherwise the 'backing' option can be omitted. 4925 */ 4926 bdrv_graph_rdlock_main_loop(); 4927 if (drv->supports_backing && reopen_state->backing_missing && 4928 (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) { 4929 error_setg(errp, "backing is missing for '%s'", 4930 reopen_state->bs->node_name); 4931 bdrv_graph_rdunlock_main_loop(); 4932 ret = -EINVAL; 4933 goto error; 4934 } 4935 bdrv_graph_rdunlock_main_loop(); 4936 4937 /* 4938 * Allow changing the 'backing' option. The new value can be 4939 * either a reference to an existing node (using its node name) 4940 * or NULL to simply detach the current backing file. 4941 */ 4942 ret = bdrv_reopen_parse_file_or_backing(reopen_state, true, 4943 change_child_tran, errp); 4944 if (ret < 0) { 4945 goto error; 4946 } 4947 qdict_del(reopen_state->options, "backing"); 4948 4949 /* Allow changing the 'file' option. In this case NULL is not allowed */ 4950 ret = bdrv_reopen_parse_file_or_backing(reopen_state, false, 4951 change_child_tran, errp); 4952 if (ret < 0) { 4953 goto error; 4954 } 4955 qdict_del(reopen_state->options, "file"); 4956 4957 /* Options that are not handled are only okay if they are unchanged 4958 * compared to the old state. It is expected that some options are only 4959 * used for the initial open, but not reopen (e.g. filename) */ 4960 if (qdict_size(reopen_state->options)) { 4961 const QDictEntry *entry = qdict_first(reopen_state->options); 4962 4963 GRAPH_RDLOCK_GUARD_MAINLOOP(); 4964 4965 do { 4966 QObject *new = entry->value; 4967 QObject *old = qdict_get(reopen_state->bs->options, entry->key); 4968 4969 /* Allow child references (child_name=node_name) as long as they 4970 * point to the current child (i.e. everything stays the same). */ 4971 if (qobject_type(new) == QTYPE_QSTRING) { 4972 BdrvChild *child; 4973 QLIST_FOREACH(child, &reopen_state->bs->children, next) { 4974 if (!strcmp(child->name, entry->key)) { 4975 break; 4976 } 4977 } 4978 4979 if (child) { 4980 if (!strcmp(child->bs->node_name, 4981 qstring_get_str(qobject_to(QString, new)))) { 4982 continue; /* Found child with this name, skip option */ 4983 } 4984 } 4985 } 4986 4987 /* 4988 * TODO: When using -drive to specify blockdev options, all values 4989 * will be strings; however, when using -blockdev, blockdev-add or 4990 * filenames using the json:{} pseudo-protocol, they will be 4991 * correctly typed. 4992 * In contrast, reopening options are (currently) always strings 4993 * (because you can only specify them through qemu-io; all other 4994 * callers do not specify any options). 4995 * Therefore, when using anything other than -drive to create a BDS, 4996 * this cannot detect non-string options as unchanged, because 4997 * qobject_is_equal() always returns false for objects of different 4998 * type. In the future, this should be remedied by correctly typing 4999 * all options. For now, this is not too big of an issue because 5000 * the user can simply omit options which cannot be changed anyway, 5001 * so they will stay unchanged. 5002 */ 5003 if (!qobject_is_equal(new, old)) { 5004 error_setg(errp, "Cannot change the option '%s'", entry->key); 5005 ret = -EINVAL; 5006 goto error; 5007 } 5008 } while ((entry = qdict_next(reopen_state->options, entry))); 5009 } 5010 5011 ret = 0; 5012 5013 /* Restore the original reopen_state->options QDict */ 5014 qobject_unref(reopen_state->options); 5015 reopen_state->options = qobject_ref(orig_reopen_opts); 5016 5017 error: 5018 if (ret < 0 && drv_prepared) { 5019 /* drv->bdrv_reopen_prepare() has succeeded, so we need to 5020 * call drv->bdrv_reopen_abort() before signaling an error 5021 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort() 5022 * when the respective bdrv_reopen_prepare() has failed) */ 5023 if (drv->bdrv_reopen_abort) { 5024 drv->bdrv_reopen_abort(reopen_state); 5025 } 5026 } 5027 qemu_opts_del(opts); 5028 qobject_unref(orig_reopen_opts); 5029 g_free(discard); 5030 return ret; 5031 } 5032 5033 /* 5034 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and 5035 * makes them final by swapping the staging BlockDriverState contents into 5036 * the active BlockDriverState contents. 5037 */ 5038 static void GRAPH_UNLOCKED bdrv_reopen_commit(BDRVReopenState *reopen_state) 5039 { 5040 BlockDriver *drv; 5041 BlockDriverState *bs; 5042 BdrvChild *child; 5043 5044 assert(reopen_state != NULL); 5045 bs = reopen_state->bs; 5046 drv = bs->drv; 5047 assert(drv != NULL); 5048 GLOBAL_STATE_CODE(); 5049 5050 /* If there are any driver level actions to take */ 5051 if (drv->bdrv_reopen_commit) { 5052 drv->bdrv_reopen_commit(reopen_state); 5053 } 5054 5055 GRAPH_RDLOCK_GUARD_MAINLOOP(); 5056 5057 /* set BDS specific flags now */ 5058 qobject_unref(bs->explicit_options); 5059 qobject_unref(bs->options); 5060 qobject_ref(reopen_state->explicit_options); 5061 qobject_ref(reopen_state->options); 5062 5063 bs->explicit_options = reopen_state->explicit_options; 5064 bs->options = reopen_state->options; 5065 bs->open_flags = reopen_state->flags; 5066 bs->detect_zeroes = reopen_state->detect_zeroes; 5067 5068 /* Remove child references from bs->options and bs->explicit_options. 5069 * Child options were already removed in bdrv_reopen_queue_child() */ 5070 QLIST_FOREACH(child, &bs->children, next) { 5071 qdict_del(bs->explicit_options, child->name); 5072 qdict_del(bs->options, child->name); 5073 } 5074 /* backing is probably removed, so it's not handled by previous loop */ 5075 qdict_del(bs->explicit_options, "backing"); 5076 qdict_del(bs->options, "backing"); 5077 5078 bdrv_refresh_limits(bs, NULL, NULL); 5079 bdrv_refresh_total_sectors(bs, bs->total_sectors); 5080 } 5081 5082 /* 5083 * Abort the reopen, and delete and free the staged changes in 5084 * reopen_state 5085 */ 5086 static void GRAPH_UNLOCKED bdrv_reopen_abort(BDRVReopenState *reopen_state) 5087 { 5088 BlockDriver *drv; 5089 5090 assert(reopen_state != NULL); 5091 drv = reopen_state->bs->drv; 5092 assert(drv != NULL); 5093 GLOBAL_STATE_CODE(); 5094 5095 if (drv->bdrv_reopen_abort) { 5096 drv->bdrv_reopen_abort(reopen_state); 5097 } 5098 } 5099 5100 5101 static void bdrv_close(BlockDriverState *bs) 5102 { 5103 BdrvAioNotifier *ban, *ban_next; 5104 BdrvChild *child, *next; 5105 5106 GLOBAL_STATE_CODE(); 5107 assert(!bs->refcnt); 5108 5109 bdrv_drained_begin(bs); /* complete I/O */ 5110 bdrv_flush(bs); 5111 bdrv_drain(bs); /* in case flush left pending I/O */ 5112 5113 if (bs->drv) { 5114 if (bs->drv->bdrv_close) { 5115 /* Must unfreeze all children, so bdrv_unref_child() works */ 5116 bs->drv->bdrv_close(bs); 5117 } 5118 bs->drv = NULL; 5119 } 5120 5121 bdrv_graph_wrlock(); 5122 QLIST_FOREACH_SAFE(child, &bs->children, next, next) { 5123 bdrv_unref_child(bs, child); 5124 } 5125 5126 assert(!bs->backing); 5127 assert(!bs->file); 5128 bdrv_graph_wrunlock(); 5129 5130 g_free(bs->opaque); 5131 bs->opaque = NULL; 5132 qatomic_set(&bs->copy_on_read, 0); 5133 bs->backing_file[0] = '\0'; 5134 bs->backing_format[0] = '\0'; 5135 bs->total_sectors = 0; 5136 bs->encrypted = false; 5137 bs->sg = false; 5138 qobject_unref(bs->options); 5139 qobject_unref(bs->explicit_options); 5140 bs->options = NULL; 5141 bs->explicit_options = NULL; 5142 qobject_unref(bs->full_open_options); 5143 bs->full_open_options = NULL; 5144 g_free(bs->block_status_cache); 5145 bs->block_status_cache = NULL; 5146 5147 bdrv_release_named_dirty_bitmaps(bs); 5148 assert(QLIST_EMPTY(&bs->dirty_bitmaps)); 5149 5150 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 5151 g_free(ban); 5152 } 5153 QLIST_INIT(&bs->aio_notifiers); 5154 bdrv_drained_end(bs); 5155 5156 /* 5157 * If we're still inside some bdrv_drain_all_begin()/end() sections, end 5158 * them now since this BDS won't exist anymore when bdrv_drain_all_end() 5159 * gets called. 5160 */ 5161 if (bs->quiesce_counter) { 5162 bdrv_drain_all_end_quiesce(bs); 5163 } 5164 } 5165 5166 void bdrv_close_all(void) 5167 { 5168 GLOBAL_STATE_CODE(); 5169 assert(job_next(NULL) == NULL); 5170 5171 /* Drop references from requests still in flight, such as canceled block 5172 * jobs whose AIO context has not been polled yet */ 5173 bdrv_drain_all(); 5174 5175 blk_remove_all_bs(); 5176 blockdev_close_all_bdrv_states(); 5177 5178 assert(QTAILQ_EMPTY(&all_bdrv_states)); 5179 } 5180 5181 static bool GRAPH_RDLOCK should_update_child(BdrvChild *c, BlockDriverState *to) 5182 { 5183 GQueue *queue; 5184 GHashTable *found; 5185 bool ret; 5186 5187 if (c->klass->stay_at_node) { 5188 return false; 5189 } 5190 5191 /* If the child @c belongs to the BDS @to, replacing the current 5192 * c->bs by @to would mean to create a loop. 5193 * 5194 * Such a case occurs when appending a BDS to a backing chain. 5195 * For instance, imagine the following chain: 5196 * 5197 * guest device -> node A -> further backing chain... 5198 * 5199 * Now we create a new BDS B which we want to put on top of this 5200 * chain, so we first attach A as its backing node: 5201 * 5202 * node B 5203 * | 5204 * v 5205 * guest device -> node A -> further backing chain... 5206 * 5207 * Finally we want to replace A by B. When doing that, we want to 5208 * replace all pointers to A by pointers to B -- except for the 5209 * pointer from B because (1) that would create a loop, and (2) 5210 * that pointer should simply stay intact: 5211 * 5212 * guest device -> node B 5213 * | 5214 * v 5215 * node A -> further backing chain... 5216 * 5217 * In general, when replacing a node A (c->bs) by a node B (@to), 5218 * if A is a child of B, that means we cannot replace A by B there 5219 * because that would create a loop. Silently detaching A from B 5220 * is also not really an option. So overall just leaving A in 5221 * place there is the most sensible choice. 5222 * 5223 * We would also create a loop in any cases where @c is only 5224 * indirectly referenced by @to. Prevent this by returning false 5225 * if @c is found (by breadth-first search) anywhere in the whole 5226 * subtree of @to. 5227 */ 5228 5229 ret = true; 5230 found = g_hash_table_new(NULL, NULL); 5231 g_hash_table_add(found, to); 5232 queue = g_queue_new(); 5233 g_queue_push_tail(queue, to); 5234 5235 while (!g_queue_is_empty(queue)) { 5236 BlockDriverState *v = g_queue_pop_head(queue); 5237 BdrvChild *c2; 5238 5239 QLIST_FOREACH(c2, &v->children, next) { 5240 if (c2 == c) { 5241 ret = false; 5242 break; 5243 } 5244 5245 if (g_hash_table_contains(found, c2->bs)) { 5246 continue; 5247 } 5248 5249 g_queue_push_tail(queue, c2->bs); 5250 g_hash_table_add(found, c2->bs); 5251 } 5252 } 5253 5254 g_queue_free(queue); 5255 g_hash_table_destroy(found); 5256 5257 return ret; 5258 } 5259 5260 static void bdrv_remove_child_commit(void *opaque) 5261 { 5262 GLOBAL_STATE_CODE(); 5263 bdrv_child_free(opaque); 5264 } 5265 5266 static TransactionActionDrv bdrv_remove_child_drv = { 5267 .commit = bdrv_remove_child_commit, 5268 }; 5269 5270 /* 5271 * Function doesn't update permissions, caller is responsible for this. 5272 * 5273 * @child->bs (if non-NULL) must be drained. 5274 * 5275 * After calling this function, the transaction @tran may only be completed 5276 * while holding a writer lock for the graph. 5277 */ 5278 static void GRAPH_WRLOCK bdrv_remove_child(BdrvChild *child, Transaction *tran) 5279 { 5280 if (!child) { 5281 return; 5282 } 5283 5284 if (child->bs) { 5285 assert(child->quiesced_parent); 5286 bdrv_replace_child_tran(child, NULL, tran); 5287 } 5288 5289 tran_add(tran, &bdrv_remove_child_drv, child); 5290 } 5291 5292 /* 5293 * Both @from and @to (if non-NULL) must be drained. @to must be kept drained 5294 * until the transaction is completed. 5295 * 5296 * After calling this function, the transaction @tran may only be completed 5297 * while holding a writer lock for the graph. 5298 */ 5299 static int GRAPH_WRLOCK 5300 bdrv_replace_node_noperm(BlockDriverState *from, 5301 BlockDriverState *to, 5302 bool auto_skip, Transaction *tran, 5303 Error **errp) 5304 { 5305 BdrvChild *c, *next; 5306 5307 GLOBAL_STATE_CODE(); 5308 5309 assert(from->quiesce_counter); 5310 assert(to->quiesce_counter); 5311 5312 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { 5313 assert(c->bs == from); 5314 if (!should_update_child(c, to)) { 5315 if (auto_skip) { 5316 continue; 5317 } 5318 error_setg(errp, "Should not change '%s' link to '%s'", 5319 c->name, from->node_name); 5320 return -EINVAL; 5321 } 5322 if (c->frozen) { 5323 error_setg(errp, "Cannot change '%s' link to '%s'", 5324 c->name, from->node_name); 5325 return -EPERM; 5326 } 5327 bdrv_replace_child_tran(c, to, tran); 5328 } 5329 5330 return 0; 5331 } 5332 5333 /* 5334 * Switch all parents of @from to point to @to instead. @from and @to must be in 5335 * the same AioContext and both must be drained. 5336 * 5337 * With auto_skip=true bdrv_replace_node_common skips updating from parents 5338 * if it creates a parent-child relation loop or if parent is block-job. 5339 * 5340 * With auto_skip=false the error is returned if from has a parent which should 5341 * not be updated. 5342 * 5343 * With @detach_subchain=true @to must be in a backing chain of @from. In this 5344 * case backing link of the cow-parent of @to is removed. 5345 */ 5346 static int GRAPH_WRLOCK 5347 bdrv_replace_node_common(BlockDriverState *from, BlockDriverState *to, 5348 bool auto_skip, bool detach_subchain, Error **errp) 5349 { 5350 Transaction *tran = tran_new(); 5351 g_autoptr(GSList) refresh_list = NULL; 5352 BlockDriverState *to_cow_parent = NULL; 5353 int ret; 5354 5355 GLOBAL_STATE_CODE(); 5356 5357 assert(from->quiesce_counter); 5358 assert(to->quiesce_counter); 5359 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to)); 5360 5361 if (detach_subchain) { 5362 assert(bdrv_chain_contains(from, to)); 5363 assert(from != to); 5364 for (to_cow_parent = from; 5365 bdrv_filter_or_cow_bs(to_cow_parent) != to; 5366 to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent)) 5367 { 5368 ; 5369 } 5370 } 5371 5372 /* 5373 * Do the replacement without permission update. 5374 * Replacement may influence the permissions, we should calculate new 5375 * permissions based on new graph. If we fail, we'll roll-back the 5376 * replacement. 5377 */ 5378 ret = bdrv_replace_node_noperm(from, to, auto_skip, tran, errp); 5379 if (ret < 0) { 5380 goto out; 5381 } 5382 5383 if (detach_subchain) { 5384 /* to_cow_parent is already drained because from is drained */ 5385 bdrv_remove_child(bdrv_filter_or_cow_child(to_cow_parent), tran); 5386 } 5387 5388 refresh_list = g_slist_prepend(refresh_list, to); 5389 refresh_list = g_slist_prepend(refresh_list, from); 5390 5391 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp); 5392 if (ret < 0) { 5393 goto out; 5394 } 5395 5396 ret = 0; 5397 5398 out: 5399 tran_finalize(tran, ret); 5400 return ret; 5401 } 5402 5403 int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, 5404 Error **errp) 5405 { 5406 return bdrv_replace_node_common(from, to, true, false, errp); 5407 } 5408 5409 int bdrv_drop_filter(BlockDriverState *bs, Error **errp) 5410 { 5411 BlockDriverState *child_bs; 5412 int ret; 5413 5414 GLOBAL_STATE_CODE(); 5415 5416 bdrv_graph_rdlock_main_loop(); 5417 child_bs = bdrv_filter_or_cow_bs(bs); 5418 bdrv_graph_rdunlock_main_loop(); 5419 5420 bdrv_drained_begin(child_bs); 5421 bdrv_graph_wrlock(); 5422 ret = bdrv_replace_node_common(bs, child_bs, true, true, errp); 5423 bdrv_graph_wrunlock(); 5424 bdrv_drained_end(child_bs); 5425 5426 return ret; 5427 } 5428 5429 /* 5430 * Add new bs contents at the top of an image chain while the chain is 5431 * live, while keeping required fields on the top layer. 5432 * 5433 * This will modify the BlockDriverState fields, and swap contents 5434 * between bs_new and bs_top. Both bs_new and bs_top are modified. 5435 * 5436 * bs_new must not be attached to a BlockBackend and must not have backing 5437 * child. 5438 * 5439 * This function does not create any image files. 5440 * 5441 * The caller must hold the AioContext lock for @bs_top. 5442 */ 5443 int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, 5444 Error **errp) 5445 { 5446 int ret; 5447 BdrvChild *child; 5448 Transaction *tran = tran_new(); 5449 5450 GLOBAL_STATE_CODE(); 5451 5452 bdrv_graph_rdlock_main_loop(); 5453 assert(!bs_new->backing); 5454 bdrv_graph_rdunlock_main_loop(); 5455 5456 bdrv_drained_begin(bs_top); 5457 bdrv_drained_begin(bs_new); 5458 5459 bdrv_graph_wrlock(); 5460 5461 child = bdrv_attach_child_noperm(bs_new, bs_top, "backing", 5462 &child_of_bds, bdrv_backing_role(bs_new), 5463 tran, errp); 5464 if (!child) { 5465 ret = -EINVAL; 5466 goto out; 5467 } 5468 5469 ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp); 5470 if (ret < 0) { 5471 goto out; 5472 } 5473 5474 ret = bdrv_refresh_perms(bs_new, tran, errp); 5475 out: 5476 tran_finalize(tran, ret); 5477 5478 bdrv_refresh_limits(bs_top, NULL, NULL); 5479 bdrv_graph_wrunlock(); 5480 5481 bdrv_drained_end(bs_top); 5482 bdrv_drained_end(bs_new); 5483 5484 return ret; 5485 } 5486 5487 /* Not for empty child */ 5488 int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs, 5489 Error **errp) 5490 { 5491 int ret; 5492 Transaction *tran = tran_new(); 5493 g_autoptr(GSList) refresh_list = NULL; 5494 BlockDriverState *old_bs = child->bs; 5495 5496 GLOBAL_STATE_CODE(); 5497 5498 bdrv_ref(old_bs); 5499 bdrv_drained_begin(old_bs); 5500 bdrv_drained_begin(new_bs); 5501 bdrv_graph_wrlock(); 5502 5503 bdrv_replace_child_tran(child, new_bs, tran); 5504 5505 refresh_list = g_slist_prepend(refresh_list, old_bs); 5506 refresh_list = g_slist_prepend(refresh_list, new_bs); 5507 5508 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp); 5509 5510 tran_finalize(tran, ret); 5511 5512 bdrv_graph_wrunlock(); 5513 bdrv_drained_end(old_bs); 5514 bdrv_drained_end(new_bs); 5515 bdrv_unref(old_bs); 5516 5517 return ret; 5518 } 5519 5520 static void bdrv_delete(BlockDriverState *bs) 5521 { 5522 assert(bdrv_op_blocker_is_empty(bs)); 5523 assert(!bs->refcnt); 5524 GLOBAL_STATE_CODE(); 5525 5526 /* remove from list, if necessary */ 5527 if (bs->node_name[0] != '\0') { 5528 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list); 5529 } 5530 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list); 5531 5532 bdrv_close(bs); 5533 5534 qemu_mutex_destroy(&bs->reqs_lock); 5535 5536 g_free(bs); 5537 } 5538 5539 5540 /* 5541 * Replace @bs by newly created block node. 5542 * 5543 * @options is a QDict of options to pass to the block drivers, or NULL for an 5544 * empty set of options. The reference to the QDict belongs to the block layer 5545 * after the call (even on failure), so if the caller intends to reuse the 5546 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 5547 * 5548 * The caller holds the AioContext lock for @bs. It must make sure that @bs 5549 * stays in the same AioContext, i.e. @options must not refer to nodes in a 5550 * different AioContext. 5551 */ 5552 BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options, 5553 int flags, Error **errp) 5554 { 5555 ERRP_GUARD(); 5556 int ret; 5557 AioContext *ctx = bdrv_get_aio_context(bs); 5558 BlockDriverState *new_node_bs = NULL; 5559 const char *drvname, *node_name; 5560 BlockDriver *drv; 5561 5562 drvname = qdict_get_try_str(options, "driver"); 5563 if (!drvname) { 5564 error_setg(errp, "driver is not specified"); 5565 goto fail; 5566 } 5567 5568 drv = bdrv_find_format(drvname); 5569 if (!drv) { 5570 error_setg(errp, "Unknown driver: '%s'", drvname); 5571 goto fail; 5572 } 5573 5574 node_name = qdict_get_try_str(options, "node-name"); 5575 5576 GLOBAL_STATE_CODE(); 5577 5578 new_node_bs = bdrv_new_open_driver_opts(drv, node_name, options, flags, 5579 errp); 5580 assert(bdrv_get_aio_context(bs) == ctx); 5581 5582 options = NULL; /* bdrv_new_open_driver() eats options */ 5583 if (!new_node_bs) { 5584 error_prepend(errp, "Could not create node: "); 5585 goto fail; 5586 } 5587 5588 /* 5589 * Make sure that @bs doesn't go away until we have successfully attached 5590 * all of its parents to @new_node_bs and undrained it again. 5591 */ 5592 bdrv_ref(bs); 5593 bdrv_drained_begin(bs); 5594 bdrv_drained_begin(new_node_bs); 5595 bdrv_graph_wrlock(); 5596 ret = bdrv_replace_node(bs, new_node_bs, errp); 5597 bdrv_graph_wrunlock(); 5598 bdrv_drained_end(new_node_bs); 5599 bdrv_drained_end(bs); 5600 bdrv_unref(bs); 5601 5602 if (ret < 0) { 5603 error_prepend(errp, "Could not replace node: "); 5604 goto fail; 5605 } 5606 5607 return new_node_bs; 5608 5609 fail: 5610 qobject_unref(options); 5611 bdrv_unref(new_node_bs); 5612 return NULL; 5613 } 5614 5615 /* 5616 * Run consistency checks on an image 5617 * 5618 * Returns 0 if the check could be completed (it doesn't mean that the image is 5619 * free of errors) or -errno when an internal error occurred. The results of the 5620 * check are stored in res. 5621 */ 5622 int coroutine_fn bdrv_co_check(BlockDriverState *bs, 5623 BdrvCheckResult *res, BdrvCheckMode fix) 5624 { 5625 IO_CODE(); 5626 assert_bdrv_graph_readable(); 5627 if (bs->drv == NULL) { 5628 return -ENOMEDIUM; 5629 } 5630 if (bs->drv->bdrv_co_check == NULL) { 5631 return -ENOTSUP; 5632 } 5633 5634 memset(res, 0, sizeof(*res)); 5635 return bs->drv->bdrv_co_check(bs, res, fix); 5636 } 5637 5638 /* 5639 * Return values: 5640 * 0 - success 5641 * -EINVAL - backing format specified, but no file 5642 * -ENOSPC - can't update the backing file because no space is left in the 5643 * image file header 5644 * -ENOTSUP - format driver doesn't support changing the backing file 5645 */ 5646 int coroutine_fn 5647 bdrv_co_change_backing_file(BlockDriverState *bs, const char *backing_file, 5648 const char *backing_fmt, bool require) 5649 { 5650 BlockDriver *drv = bs->drv; 5651 int ret; 5652 5653 IO_CODE(); 5654 5655 if (!drv) { 5656 return -ENOMEDIUM; 5657 } 5658 5659 /* Backing file format doesn't make sense without a backing file */ 5660 if (backing_fmt && !backing_file) { 5661 return -EINVAL; 5662 } 5663 5664 if (require && backing_file && !backing_fmt) { 5665 return -EINVAL; 5666 } 5667 5668 if (drv->bdrv_co_change_backing_file != NULL) { 5669 ret = drv->bdrv_co_change_backing_file(bs, backing_file, backing_fmt); 5670 } else { 5671 ret = -ENOTSUP; 5672 } 5673 5674 if (ret == 0) { 5675 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: ""); 5676 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: ""); 5677 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 5678 backing_file ?: ""); 5679 } 5680 return ret; 5681 } 5682 5683 /* 5684 * Finds the first non-filter node above bs in the chain between 5685 * active and bs. The returned node is either an immediate parent of 5686 * bs, or there are only filter nodes between the two. 5687 * 5688 * Returns NULL if bs is not found in active's image chain, 5689 * or if active == bs. 5690 * 5691 * Returns the bottommost base image if bs == NULL. 5692 */ 5693 BlockDriverState *bdrv_find_overlay(BlockDriverState *active, 5694 BlockDriverState *bs) 5695 { 5696 5697 GLOBAL_STATE_CODE(); 5698 5699 bs = bdrv_skip_filters(bs); 5700 active = bdrv_skip_filters(active); 5701 5702 while (active) { 5703 BlockDriverState *next = bdrv_backing_chain_next(active); 5704 if (bs == next) { 5705 return active; 5706 } 5707 active = next; 5708 } 5709 5710 return NULL; 5711 } 5712 5713 /* Given a BDS, searches for the base layer. */ 5714 BlockDriverState *bdrv_find_base(BlockDriverState *bs) 5715 { 5716 GLOBAL_STATE_CODE(); 5717 5718 return bdrv_find_overlay(bs, NULL); 5719 } 5720 5721 /* 5722 * Return true if at least one of the COW (backing) and filter links 5723 * between @bs and @base is frozen. @errp is set if that's the case. 5724 * @base must be reachable from @bs, or NULL. 5725 */ 5726 static bool GRAPH_RDLOCK 5727 bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base, 5728 Error **errp) 5729 { 5730 BlockDriverState *i; 5731 BdrvChild *child; 5732 5733 GLOBAL_STATE_CODE(); 5734 5735 for (i = bs; i != base; i = child_bs(child)) { 5736 child = bdrv_filter_or_cow_child(i); 5737 5738 if (child && child->frozen) { 5739 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'", 5740 child->name, i->node_name, child->bs->node_name); 5741 return true; 5742 } 5743 } 5744 5745 return false; 5746 } 5747 5748 /* 5749 * Freeze all COW (backing) and filter links between @bs and @base. 5750 * If any of the links is already frozen the operation is aborted and 5751 * none of the links are modified. 5752 * @base must be reachable from @bs, or NULL. 5753 * Returns 0 on success. On failure returns < 0 and sets @errp. 5754 */ 5755 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base, 5756 Error **errp) 5757 { 5758 BlockDriverState *i; 5759 BdrvChild *child; 5760 5761 GLOBAL_STATE_CODE(); 5762 5763 if (bdrv_is_backing_chain_frozen(bs, base, errp)) { 5764 return -EPERM; 5765 } 5766 5767 for (i = bs; i != base; i = child_bs(child)) { 5768 child = bdrv_filter_or_cow_child(i); 5769 if (child && child->bs->never_freeze) { 5770 error_setg(errp, "Cannot freeze '%s' link to '%s'", 5771 child->name, child->bs->node_name); 5772 return -EPERM; 5773 } 5774 } 5775 5776 for (i = bs; i != base; i = child_bs(child)) { 5777 child = bdrv_filter_or_cow_child(i); 5778 if (child) { 5779 child->frozen = true; 5780 } 5781 } 5782 5783 return 0; 5784 } 5785 5786 /* 5787 * Unfreeze all COW (backing) and filter links between @bs and @base. 5788 * The caller must ensure that all links are frozen before using this 5789 * function. 5790 * @base must be reachable from @bs, or NULL. 5791 */ 5792 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base) 5793 { 5794 BlockDriverState *i; 5795 BdrvChild *child; 5796 5797 GLOBAL_STATE_CODE(); 5798 5799 for (i = bs; i != base; i = child_bs(child)) { 5800 child = bdrv_filter_or_cow_child(i); 5801 if (child) { 5802 assert(child->frozen); 5803 child->frozen = false; 5804 } 5805 } 5806 } 5807 5808 /* 5809 * Drops images above 'base' up to and including 'top', and sets the image 5810 * above 'top' to have base as its backing file. 5811 * 5812 * Requires that the overlay to 'top' is opened r/w, so that the backing file 5813 * information in 'bs' can be properly updated. 5814 * 5815 * E.g., this will convert the following chain: 5816 * bottom <- base <- intermediate <- top <- active 5817 * 5818 * to 5819 * 5820 * bottom <- base <- active 5821 * 5822 * It is allowed for bottom==base, in which case it converts: 5823 * 5824 * base <- intermediate <- top <- active 5825 * 5826 * to 5827 * 5828 * base <- active 5829 * 5830 * If backing_file_str is non-NULL, it will be used when modifying top's 5831 * overlay image metadata. 5832 * 5833 * Error conditions: 5834 * if active == top, that is considered an error 5835 * 5836 */ 5837 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, 5838 const char *backing_file_str) 5839 { 5840 BlockDriverState *explicit_top = top; 5841 bool update_inherits_from; 5842 BdrvChild *c; 5843 Error *local_err = NULL; 5844 int ret = -EIO; 5845 g_autoptr(GSList) updated_children = NULL; 5846 GSList *p; 5847 5848 GLOBAL_STATE_CODE(); 5849 5850 bdrv_ref(top); 5851 bdrv_drained_begin(base); 5852 bdrv_graph_wrlock(); 5853 5854 if (!top->drv || !base->drv) { 5855 goto exit_wrlock; 5856 } 5857 5858 /* Make sure that base is in the backing chain of top */ 5859 if (!bdrv_chain_contains(top, base)) { 5860 goto exit_wrlock; 5861 } 5862 5863 /* If 'base' recursively inherits from 'top' then we should set 5864 * base->inherits_from to top->inherits_from after 'top' and all 5865 * other intermediate nodes have been dropped. 5866 * If 'top' is an implicit node (e.g. "commit_top") we should skip 5867 * it because no one inherits from it. We use explicit_top for that. */ 5868 explicit_top = bdrv_skip_implicit_filters(explicit_top); 5869 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top); 5870 5871 /* success - we can delete the intermediate states, and link top->base */ 5872 if (!backing_file_str) { 5873 bdrv_refresh_filename(base); 5874 backing_file_str = base->filename; 5875 } 5876 5877 QLIST_FOREACH(c, &top->parents, next_parent) { 5878 updated_children = g_slist_prepend(updated_children, c); 5879 } 5880 5881 /* 5882 * It seems correct to pass detach_subchain=true here, but it triggers 5883 * one more yet not fixed bug, when due to nested aio_poll loop we switch to 5884 * another drained section, which modify the graph (for example, removing 5885 * the child, which we keep in updated_children list). So, it's a TODO. 5886 * 5887 * Note, bug triggered if pass detach_subchain=true here and run 5888 * test-bdrv-drain. test_drop_intermediate_poll() test-case will crash. 5889 * That's a FIXME. 5890 */ 5891 bdrv_replace_node_common(top, base, false, false, &local_err); 5892 bdrv_graph_wrunlock(); 5893 5894 if (local_err) { 5895 error_report_err(local_err); 5896 goto exit; 5897 } 5898 5899 for (p = updated_children; p; p = p->next) { 5900 c = p->data; 5901 5902 if (c->klass->update_filename) { 5903 ret = c->klass->update_filename(c, base, backing_file_str, 5904 &local_err); 5905 if (ret < 0) { 5906 /* 5907 * TODO: Actually, we want to rollback all previous iterations 5908 * of this loop, and (which is almost impossible) previous 5909 * bdrv_replace_node()... 5910 * 5911 * Note, that c->klass->update_filename may lead to permission 5912 * update, so it's a bad idea to call it inside permission 5913 * update transaction of bdrv_replace_node. 5914 */ 5915 error_report_err(local_err); 5916 goto exit; 5917 } 5918 } 5919 } 5920 5921 if (update_inherits_from) { 5922 base->inherits_from = explicit_top->inherits_from; 5923 } 5924 5925 ret = 0; 5926 goto exit; 5927 5928 exit_wrlock: 5929 bdrv_graph_wrunlock(); 5930 exit: 5931 bdrv_drained_end(base); 5932 bdrv_unref(top); 5933 return ret; 5934 } 5935 5936 /** 5937 * Implementation of BlockDriver.bdrv_co_get_allocated_file_size() that 5938 * sums the size of all data-bearing children. (This excludes backing 5939 * children.) 5940 */ 5941 static int64_t coroutine_fn GRAPH_RDLOCK 5942 bdrv_sum_allocated_file_size(BlockDriverState *bs) 5943 { 5944 BdrvChild *child; 5945 int64_t child_size, sum = 0; 5946 5947 QLIST_FOREACH(child, &bs->children, next) { 5948 if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | 5949 BDRV_CHILD_FILTERED)) 5950 { 5951 child_size = bdrv_co_get_allocated_file_size(child->bs); 5952 if (child_size < 0) { 5953 return child_size; 5954 } 5955 sum += child_size; 5956 } 5957 } 5958 5959 return sum; 5960 } 5961 5962 /** 5963 * Length of a allocated file in bytes. Sparse files are counted by actual 5964 * allocated space. Return < 0 if error or unknown. 5965 */ 5966 int64_t coroutine_fn bdrv_co_get_allocated_file_size(BlockDriverState *bs) 5967 { 5968 BlockDriver *drv = bs->drv; 5969 IO_CODE(); 5970 assert_bdrv_graph_readable(); 5971 5972 if (!drv) { 5973 return -ENOMEDIUM; 5974 } 5975 if (drv->bdrv_co_get_allocated_file_size) { 5976 return drv->bdrv_co_get_allocated_file_size(bs); 5977 } 5978 5979 if (drv->bdrv_file_open) { 5980 /* 5981 * Protocol drivers default to -ENOTSUP (most of their data is 5982 * not stored in any of their children (if they even have any), 5983 * so there is no generic way to figure it out). 5984 */ 5985 return -ENOTSUP; 5986 } else if (drv->is_filter) { 5987 /* Filter drivers default to the size of their filtered child */ 5988 return bdrv_co_get_allocated_file_size(bdrv_filter_bs(bs)); 5989 } else { 5990 /* Other drivers default to summing their children's sizes */ 5991 return bdrv_sum_allocated_file_size(bs); 5992 } 5993 } 5994 5995 /* 5996 * bdrv_measure: 5997 * @drv: Format driver 5998 * @opts: Creation options for new image 5999 * @in_bs: Existing image containing data for new image (may be NULL) 6000 * @errp: Error object 6001 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo()) 6002 * or NULL on error 6003 * 6004 * Calculate file size required to create a new image. 6005 * 6006 * If @in_bs is given then space for allocated clusters and zero clusters 6007 * from that image are included in the calculation. If @opts contains a 6008 * backing file that is shared by @in_bs then backing clusters may be omitted 6009 * from the calculation. 6010 * 6011 * If @in_bs is NULL then the calculation includes no allocated clusters 6012 * unless a preallocation option is given in @opts. 6013 * 6014 * Note that @in_bs may use a different BlockDriver from @drv. 6015 * 6016 * If an error occurs the @errp pointer is set. 6017 */ 6018 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, 6019 BlockDriverState *in_bs, Error **errp) 6020 { 6021 IO_CODE(); 6022 if (!drv->bdrv_measure) { 6023 error_setg(errp, "Block driver '%s' does not support size measurement", 6024 drv->format_name); 6025 return NULL; 6026 } 6027 6028 return drv->bdrv_measure(opts, in_bs, errp); 6029 } 6030 6031 /** 6032 * Return number of sectors on success, -errno on error. 6033 */ 6034 int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs) 6035 { 6036 BlockDriver *drv = bs->drv; 6037 IO_CODE(); 6038 assert_bdrv_graph_readable(); 6039 6040 if (!drv) 6041 return -ENOMEDIUM; 6042 6043 if (bs->bl.has_variable_length) { 6044 int ret = bdrv_co_refresh_total_sectors(bs, bs->total_sectors); 6045 if (ret < 0) { 6046 return ret; 6047 } 6048 } 6049 return bs->total_sectors; 6050 } 6051 6052 /* 6053 * This wrapper is written by hand because this function is in the hot I/O path, 6054 * via blk_get_geometry. 6055 */ 6056 int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs) 6057 { 6058 BlockDriver *drv = bs->drv; 6059 IO_CODE(); 6060 6061 if (!drv) 6062 return -ENOMEDIUM; 6063 6064 if (bs->bl.has_variable_length) { 6065 int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); 6066 if (ret < 0) { 6067 return ret; 6068 } 6069 } 6070 6071 return bs->total_sectors; 6072 } 6073 6074 /** 6075 * Return length in bytes on success, -errno on error. 6076 * The length is always a multiple of BDRV_SECTOR_SIZE. 6077 */ 6078 int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs) 6079 { 6080 int64_t ret; 6081 IO_CODE(); 6082 assert_bdrv_graph_readable(); 6083 6084 ret = bdrv_co_nb_sectors(bs); 6085 if (ret < 0) { 6086 return ret; 6087 } 6088 if (ret > INT64_MAX / BDRV_SECTOR_SIZE) { 6089 return -EFBIG; 6090 } 6091 return ret * BDRV_SECTOR_SIZE; 6092 } 6093 6094 bool bdrv_is_sg(BlockDriverState *bs) 6095 { 6096 IO_CODE(); 6097 return bs->sg; 6098 } 6099 6100 /** 6101 * Return whether the given node supports compressed writes. 6102 */ 6103 bool bdrv_supports_compressed_writes(BlockDriverState *bs) 6104 { 6105 BlockDriverState *filtered; 6106 IO_CODE(); 6107 6108 if (!bs->drv || !block_driver_can_compress(bs->drv)) { 6109 return false; 6110 } 6111 6112 filtered = bdrv_filter_bs(bs); 6113 if (filtered) { 6114 /* 6115 * Filters can only forward compressed writes, so we have to 6116 * check the child. 6117 */ 6118 return bdrv_supports_compressed_writes(filtered); 6119 } 6120 6121 return true; 6122 } 6123 6124 const char *bdrv_get_format_name(BlockDriverState *bs) 6125 { 6126 IO_CODE(); 6127 return bs->drv ? bs->drv->format_name : NULL; 6128 } 6129 6130 static int qsort_strcmp(const void *a, const void *b) 6131 { 6132 return strcmp(*(char *const *)a, *(char *const *)b); 6133 } 6134 6135 void bdrv_iterate_format(void (*it)(void *opaque, const char *name), 6136 void *opaque, bool read_only) 6137 { 6138 BlockDriver *drv; 6139 int count = 0; 6140 int i; 6141 const char **formats = NULL; 6142 6143 GLOBAL_STATE_CODE(); 6144 6145 QLIST_FOREACH(drv, &bdrv_drivers, list) { 6146 if (drv->format_name) { 6147 bool found = false; 6148 6149 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) { 6150 continue; 6151 } 6152 6153 i = count; 6154 while (formats && i && !found) { 6155 found = !strcmp(formats[--i], drv->format_name); 6156 } 6157 6158 if (!found) { 6159 formats = g_renew(const char *, formats, count + 1); 6160 formats[count++] = drv->format_name; 6161 } 6162 } 6163 } 6164 6165 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) { 6166 const char *format_name = block_driver_modules[i].format_name; 6167 6168 if (format_name) { 6169 bool found = false; 6170 int j = count; 6171 6172 if (use_bdrv_whitelist && 6173 !bdrv_format_is_whitelisted(format_name, read_only)) { 6174 continue; 6175 } 6176 6177 while (formats && j && !found) { 6178 found = !strcmp(formats[--j], format_name); 6179 } 6180 6181 if (!found) { 6182 formats = g_renew(const char *, formats, count + 1); 6183 formats[count++] = format_name; 6184 } 6185 } 6186 } 6187 6188 qsort(formats, count, sizeof(formats[0]), qsort_strcmp); 6189 6190 for (i = 0; i < count; i++) { 6191 it(opaque, formats[i]); 6192 } 6193 6194 g_free(formats); 6195 } 6196 6197 /* This function is to find a node in the bs graph */ 6198 BlockDriverState *bdrv_find_node(const char *node_name) 6199 { 6200 BlockDriverState *bs; 6201 6202 assert(node_name); 6203 GLOBAL_STATE_CODE(); 6204 6205 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 6206 if (!strcmp(node_name, bs->node_name)) { 6207 return bs; 6208 } 6209 } 6210 return NULL; 6211 } 6212 6213 /* Put this QMP function here so it can access the static graph_bdrv_states. */ 6214 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat, 6215 Error **errp) 6216 { 6217 BlockDeviceInfoList *list; 6218 BlockDriverState *bs; 6219 6220 GLOBAL_STATE_CODE(); 6221 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6222 6223 list = NULL; 6224 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 6225 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp); 6226 if (!info) { 6227 qapi_free_BlockDeviceInfoList(list); 6228 return NULL; 6229 } 6230 QAPI_LIST_PREPEND(list, info); 6231 } 6232 6233 return list; 6234 } 6235 6236 typedef struct XDbgBlockGraphConstructor { 6237 XDbgBlockGraph *graph; 6238 GHashTable *graph_nodes; 6239 } XDbgBlockGraphConstructor; 6240 6241 static XDbgBlockGraphConstructor *xdbg_graph_new(void) 6242 { 6243 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1); 6244 6245 gr->graph = g_new0(XDbgBlockGraph, 1); 6246 gr->graph_nodes = g_hash_table_new(NULL, NULL); 6247 6248 return gr; 6249 } 6250 6251 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr) 6252 { 6253 XDbgBlockGraph *graph = gr->graph; 6254 6255 g_hash_table_destroy(gr->graph_nodes); 6256 g_free(gr); 6257 6258 return graph; 6259 } 6260 6261 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node) 6262 { 6263 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node); 6264 6265 if (ret != 0) { 6266 return ret; 6267 } 6268 6269 /* 6270 * Start counting from 1, not 0, because 0 interferes with not-found (NULL) 6271 * answer of g_hash_table_lookup. 6272 */ 6273 ret = g_hash_table_size(gr->graph_nodes) + 1; 6274 g_hash_table_insert(gr->graph_nodes, node, (void *)ret); 6275 6276 return ret; 6277 } 6278 6279 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node, 6280 XDbgBlockGraphNodeType type, const char *name) 6281 { 6282 XDbgBlockGraphNode *n; 6283 6284 n = g_new0(XDbgBlockGraphNode, 1); 6285 6286 n->id = xdbg_graph_node_num(gr, node); 6287 n->type = type; 6288 n->name = g_strdup(name); 6289 6290 QAPI_LIST_PREPEND(gr->graph->nodes, n); 6291 } 6292 6293 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent, 6294 const BdrvChild *child) 6295 { 6296 BlockPermission qapi_perm; 6297 XDbgBlockGraphEdge *edge; 6298 GLOBAL_STATE_CODE(); 6299 6300 edge = g_new0(XDbgBlockGraphEdge, 1); 6301 6302 edge->parent = xdbg_graph_node_num(gr, parent); 6303 edge->child = xdbg_graph_node_num(gr, child->bs); 6304 edge->name = g_strdup(child->name); 6305 6306 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) { 6307 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm); 6308 6309 if (flag & child->perm) { 6310 QAPI_LIST_PREPEND(edge->perm, qapi_perm); 6311 } 6312 if (flag & child->shared_perm) { 6313 QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm); 6314 } 6315 } 6316 6317 QAPI_LIST_PREPEND(gr->graph->edges, edge); 6318 } 6319 6320 6321 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp) 6322 { 6323 BlockBackend *blk; 6324 BlockJob *job; 6325 BlockDriverState *bs; 6326 BdrvChild *child; 6327 XDbgBlockGraphConstructor *gr = xdbg_graph_new(); 6328 6329 GLOBAL_STATE_CODE(); 6330 6331 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) { 6332 char *allocated_name = NULL; 6333 const char *name = blk_name(blk); 6334 6335 if (!*name) { 6336 name = allocated_name = blk_get_attached_dev_id(blk); 6337 } 6338 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND, 6339 name); 6340 g_free(allocated_name); 6341 if (blk_root(blk)) { 6342 xdbg_graph_add_edge(gr, blk, blk_root(blk)); 6343 } 6344 } 6345 6346 WITH_JOB_LOCK_GUARD() { 6347 for (job = block_job_next_locked(NULL); job; 6348 job = block_job_next_locked(job)) { 6349 GSList *el; 6350 6351 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB, 6352 job->job.id); 6353 for (el = job->nodes; el; el = el->next) { 6354 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data); 6355 } 6356 } 6357 } 6358 6359 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 6360 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER, 6361 bs->node_name); 6362 QLIST_FOREACH(child, &bs->children, next) { 6363 xdbg_graph_add_edge(gr, bs, child); 6364 } 6365 } 6366 6367 return xdbg_graph_finalize(gr); 6368 } 6369 6370 BlockDriverState *bdrv_lookup_bs(const char *device, 6371 const char *node_name, 6372 Error **errp) 6373 { 6374 BlockBackend *blk; 6375 BlockDriverState *bs; 6376 6377 GLOBAL_STATE_CODE(); 6378 6379 if (device) { 6380 blk = blk_by_name(device); 6381 6382 if (blk) { 6383 bs = blk_bs(blk); 6384 if (!bs) { 6385 error_setg(errp, "Device '%s' has no medium", device); 6386 } 6387 6388 return bs; 6389 } 6390 } 6391 6392 if (node_name) { 6393 bs = bdrv_find_node(node_name); 6394 6395 if (bs) { 6396 return bs; 6397 } 6398 } 6399 6400 error_setg(errp, "Cannot find device=\'%s\' nor node-name=\'%s\'", 6401 device ? device : "", 6402 node_name ? node_name : ""); 6403 return NULL; 6404 } 6405 6406 /* If 'base' is in the same chain as 'top', return true. Otherwise, 6407 * return false. If either argument is NULL, return false. */ 6408 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base) 6409 { 6410 6411 GLOBAL_STATE_CODE(); 6412 6413 while (top && top != base) { 6414 top = bdrv_filter_or_cow_bs(top); 6415 } 6416 6417 return top != NULL; 6418 } 6419 6420 BlockDriverState *bdrv_next_node(BlockDriverState *bs) 6421 { 6422 GLOBAL_STATE_CODE(); 6423 if (!bs) { 6424 return QTAILQ_FIRST(&graph_bdrv_states); 6425 } 6426 return QTAILQ_NEXT(bs, node_list); 6427 } 6428 6429 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs) 6430 { 6431 GLOBAL_STATE_CODE(); 6432 if (!bs) { 6433 return QTAILQ_FIRST(&all_bdrv_states); 6434 } 6435 return QTAILQ_NEXT(bs, bs_list); 6436 } 6437 6438 const char *bdrv_get_node_name(const BlockDriverState *bs) 6439 { 6440 IO_CODE(); 6441 return bs->node_name; 6442 } 6443 6444 const char *bdrv_get_parent_name(const BlockDriverState *bs) 6445 { 6446 BdrvChild *c; 6447 const char *name; 6448 IO_CODE(); 6449 6450 /* If multiple parents have a name, just pick the first one. */ 6451 QLIST_FOREACH(c, &bs->parents, next_parent) { 6452 if (c->klass->get_name) { 6453 name = c->klass->get_name(c); 6454 if (name && *name) { 6455 return name; 6456 } 6457 } 6458 } 6459 6460 return NULL; 6461 } 6462 6463 /* TODO check what callers really want: bs->node_name or blk_name() */ 6464 const char *bdrv_get_device_name(const BlockDriverState *bs) 6465 { 6466 IO_CODE(); 6467 return bdrv_get_parent_name(bs) ?: ""; 6468 } 6469 6470 /* This can be used to identify nodes that might not have a device 6471 * name associated. Since node and device names live in the same 6472 * namespace, the result is unambiguous. The exception is if both are 6473 * absent, then this returns an empty (non-null) string. */ 6474 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs) 6475 { 6476 IO_CODE(); 6477 return bdrv_get_parent_name(bs) ?: bs->node_name; 6478 } 6479 6480 int bdrv_get_flags(BlockDriverState *bs) 6481 { 6482 IO_CODE(); 6483 return bs->open_flags; 6484 } 6485 6486 int bdrv_has_zero_init_1(BlockDriverState *bs) 6487 { 6488 GLOBAL_STATE_CODE(); 6489 return 1; 6490 } 6491 6492 int coroutine_mixed_fn bdrv_has_zero_init(BlockDriverState *bs) 6493 { 6494 BlockDriverState *filtered; 6495 GLOBAL_STATE_CODE(); 6496 6497 if (!bs->drv) { 6498 return 0; 6499 } 6500 6501 /* If BS is a copy on write image, it is initialized to 6502 the contents of the base image, which may not be zeroes. */ 6503 if (bdrv_cow_child(bs)) { 6504 return 0; 6505 } 6506 if (bs->drv->bdrv_has_zero_init) { 6507 return bs->drv->bdrv_has_zero_init(bs); 6508 } 6509 6510 filtered = bdrv_filter_bs(bs); 6511 if (filtered) { 6512 return bdrv_has_zero_init(filtered); 6513 } 6514 6515 /* safe default */ 6516 return 0; 6517 } 6518 6519 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs) 6520 { 6521 IO_CODE(); 6522 if (!(bs->open_flags & BDRV_O_UNMAP)) { 6523 return false; 6524 } 6525 6526 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP; 6527 } 6528 6529 void bdrv_get_backing_filename(BlockDriverState *bs, 6530 char *filename, int filename_size) 6531 { 6532 IO_CODE(); 6533 pstrcpy(filename, filename_size, bs->backing_file); 6534 } 6535 6536 int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) 6537 { 6538 int ret; 6539 BlockDriver *drv = bs->drv; 6540 IO_CODE(); 6541 assert_bdrv_graph_readable(); 6542 6543 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */ 6544 if (!drv) { 6545 return -ENOMEDIUM; 6546 } 6547 if (!drv->bdrv_co_get_info) { 6548 BlockDriverState *filtered = bdrv_filter_bs(bs); 6549 if (filtered) { 6550 return bdrv_co_get_info(filtered, bdi); 6551 } 6552 return -ENOTSUP; 6553 } 6554 memset(bdi, 0, sizeof(*bdi)); 6555 ret = drv->bdrv_co_get_info(bs, bdi); 6556 if (bdi->subcluster_size == 0) { 6557 /* 6558 * If the driver left this unset, subclusters are not supported. 6559 * Then it is safe to treat each cluster as having only one subcluster. 6560 */ 6561 bdi->subcluster_size = bdi->cluster_size; 6562 } 6563 if (ret < 0) { 6564 return ret; 6565 } 6566 6567 if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) { 6568 return -EINVAL; 6569 } 6570 6571 return 0; 6572 } 6573 6574 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, 6575 Error **errp) 6576 { 6577 BlockDriver *drv = bs->drv; 6578 IO_CODE(); 6579 if (drv && drv->bdrv_get_specific_info) { 6580 return drv->bdrv_get_specific_info(bs, errp); 6581 } 6582 return NULL; 6583 } 6584 6585 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs) 6586 { 6587 BlockDriver *drv = bs->drv; 6588 IO_CODE(); 6589 if (!drv || !drv->bdrv_get_specific_stats) { 6590 return NULL; 6591 } 6592 return drv->bdrv_get_specific_stats(bs); 6593 } 6594 6595 void coroutine_fn bdrv_co_debug_event(BlockDriverState *bs, BlkdebugEvent event) 6596 { 6597 IO_CODE(); 6598 assert_bdrv_graph_readable(); 6599 6600 if (!bs || !bs->drv || !bs->drv->bdrv_co_debug_event) { 6601 return; 6602 } 6603 6604 bs->drv->bdrv_co_debug_event(bs, event); 6605 } 6606 6607 static BlockDriverState * GRAPH_RDLOCK 6608 bdrv_find_debug_node(BlockDriverState *bs) 6609 { 6610 GLOBAL_STATE_CODE(); 6611 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) { 6612 bs = bdrv_primary_bs(bs); 6613 } 6614 6615 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) { 6616 assert(bs->drv->bdrv_debug_remove_breakpoint); 6617 return bs; 6618 } 6619 6620 return NULL; 6621 } 6622 6623 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event, 6624 const char *tag) 6625 { 6626 GLOBAL_STATE_CODE(); 6627 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6628 6629 bs = bdrv_find_debug_node(bs); 6630 if (bs) { 6631 return bs->drv->bdrv_debug_breakpoint(bs, event, tag); 6632 } 6633 6634 return -ENOTSUP; 6635 } 6636 6637 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag) 6638 { 6639 GLOBAL_STATE_CODE(); 6640 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6641 6642 bs = bdrv_find_debug_node(bs); 6643 if (bs) { 6644 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag); 6645 } 6646 6647 return -ENOTSUP; 6648 } 6649 6650 int bdrv_debug_resume(BlockDriverState *bs, const char *tag) 6651 { 6652 GLOBAL_STATE_CODE(); 6653 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6654 6655 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) { 6656 bs = bdrv_primary_bs(bs); 6657 } 6658 6659 if (bs && bs->drv && bs->drv->bdrv_debug_resume) { 6660 return bs->drv->bdrv_debug_resume(bs, tag); 6661 } 6662 6663 return -ENOTSUP; 6664 } 6665 6666 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag) 6667 { 6668 GLOBAL_STATE_CODE(); 6669 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6670 6671 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) { 6672 bs = bdrv_primary_bs(bs); 6673 } 6674 6675 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) { 6676 return bs->drv->bdrv_debug_is_suspended(bs, tag); 6677 } 6678 6679 return false; 6680 } 6681 6682 /* backing_file can either be relative, or absolute, or a protocol. If it is 6683 * relative, it must be relative to the chain. So, passing in bs->filename 6684 * from a BDS as backing_file should not be done, as that may be relative to 6685 * the CWD rather than the chain. */ 6686 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, 6687 const char *backing_file) 6688 { 6689 char *filename_full = NULL; 6690 char *backing_file_full = NULL; 6691 char *filename_tmp = NULL; 6692 int is_protocol = 0; 6693 bool filenames_refreshed = false; 6694 BlockDriverState *curr_bs = NULL; 6695 BlockDriverState *retval = NULL; 6696 BlockDriverState *bs_below; 6697 6698 GLOBAL_STATE_CODE(); 6699 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6700 6701 if (!bs || !bs->drv || !backing_file) { 6702 return NULL; 6703 } 6704 6705 filename_full = g_malloc(PATH_MAX); 6706 backing_file_full = g_malloc(PATH_MAX); 6707 6708 is_protocol = path_has_protocol(backing_file); 6709 6710 /* 6711 * Being largely a legacy function, skip any filters here 6712 * (because filters do not have normal filenames, so they cannot 6713 * match anyway; and allowing json:{} filenames is a bit out of 6714 * scope). 6715 */ 6716 for (curr_bs = bdrv_skip_filters(bs); 6717 bdrv_cow_child(curr_bs) != NULL; 6718 curr_bs = bs_below) 6719 { 6720 bs_below = bdrv_backing_chain_next(curr_bs); 6721 6722 if (bdrv_backing_overridden(curr_bs)) { 6723 /* 6724 * If the backing file was overridden, we can only compare 6725 * directly against the backing node's filename. 6726 */ 6727 6728 if (!filenames_refreshed) { 6729 /* 6730 * This will automatically refresh all of the 6731 * filenames in the rest of the backing chain, so we 6732 * only need to do this once. 6733 */ 6734 bdrv_refresh_filename(bs_below); 6735 filenames_refreshed = true; 6736 } 6737 6738 if (strcmp(backing_file, bs_below->filename) == 0) { 6739 retval = bs_below; 6740 break; 6741 } 6742 } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) { 6743 /* 6744 * If either of the filename paths is actually a protocol, then 6745 * compare unmodified paths; otherwise make paths relative. 6746 */ 6747 char *backing_file_full_ret; 6748 6749 if (strcmp(backing_file, curr_bs->backing_file) == 0) { 6750 retval = bs_below; 6751 break; 6752 } 6753 /* Also check against the full backing filename for the image */ 6754 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs, 6755 NULL); 6756 if (backing_file_full_ret) { 6757 bool equal = strcmp(backing_file, backing_file_full_ret) == 0; 6758 g_free(backing_file_full_ret); 6759 if (equal) { 6760 retval = bs_below; 6761 break; 6762 } 6763 } 6764 } else { 6765 /* If not an absolute filename path, make it relative to the current 6766 * image's filename path */ 6767 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file, 6768 NULL); 6769 /* We are going to compare canonicalized absolute pathnames */ 6770 if (!filename_tmp || !realpath(filename_tmp, filename_full)) { 6771 g_free(filename_tmp); 6772 continue; 6773 } 6774 g_free(filename_tmp); 6775 6776 /* We need to make sure the backing filename we are comparing against 6777 * is relative to the current image filename (or absolute) */ 6778 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL); 6779 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) { 6780 g_free(filename_tmp); 6781 continue; 6782 } 6783 g_free(filename_tmp); 6784 6785 if (strcmp(backing_file_full, filename_full) == 0) { 6786 retval = bs_below; 6787 break; 6788 } 6789 } 6790 } 6791 6792 g_free(filename_full); 6793 g_free(backing_file_full); 6794 return retval; 6795 } 6796 6797 void bdrv_init(void) 6798 { 6799 #ifdef CONFIG_BDRV_WHITELIST_TOOLS 6800 use_bdrv_whitelist = 1; 6801 #endif 6802 module_call_init(MODULE_INIT_BLOCK); 6803 } 6804 6805 void bdrv_init_with_whitelist(void) 6806 { 6807 use_bdrv_whitelist = 1; 6808 bdrv_init(); 6809 } 6810 6811 int bdrv_activate(BlockDriverState *bs, Error **errp) 6812 { 6813 BdrvChild *child, *parent; 6814 Error *local_err = NULL; 6815 int ret; 6816 BdrvDirtyBitmap *bm; 6817 6818 GLOBAL_STATE_CODE(); 6819 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6820 6821 if (!bs->drv) { 6822 return -ENOMEDIUM; 6823 } 6824 6825 QLIST_FOREACH(child, &bs->children, next) { 6826 bdrv_activate(child->bs, &local_err); 6827 if (local_err) { 6828 error_propagate(errp, local_err); 6829 return -EINVAL; 6830 } 6831 } 6832 6833 /* 6834 * Update permissions, they may differ for inactive nodes. 6835 * 6836 * Note that the required permissions of inactive images are always a 6837 * subset of the permissions required after activating the image. This 6838 * allows us to just get the permissions upfront without restricting 6839 * bdrv_co_invalidate_cache(). 6840 * 6841 * It also means that in error cases, we don't have to try and revert to 6842 * the old permissions (which is an operation that could fail, too). We can 6843 * just keep the extended permissions for the next time that an activation 6844 * of the image is tried. 6845 */ 6846 if (bs->open_flags & BDRV_O_INACTIVE) { 6847 bs->open_flags &= ~BDRV_O_INACTIVE; 6848 ret = bdrv_refresh_perms(bs, NULL, errp); 6849 if (ret < 0) { 6850 bs->open_flags |= BDRV_O_INACTIVE; 6851 return ret; 6852 } 6853 6854 ret = bdrv_invalidate_cache(bs, errp); 6855 if (ret < 0) { 6856 bs->open_flags |= BDRV_O_INACTIVE; 6857 return ret; 6858 } 6859 6860 FOR_EACH_DIRTY_BITMAP(bs, bm) { 6861 bdrv_dirty_bitmap_skip_store(bm, false); 6862 } 6863 6864 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); 6865 if (ret < 0) { 6866 bs->open_flags |= BDRV_O_INACTIVE; 6867 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 6868 return ret; 6869 } 6870 } 6871 6872 QLIST_FOREACH(parent, &bs->parents, next_parent) { 6873 if (parent->klass->activate) { 6874 parent->klass->activate(parent, &local_err); 6875 if (local_err) { 6876 bs->open_flags |= BDRV_O_INACTIVE; 6877 error_propagate(errp, local_err); 6878 return -EINVAL; 6879 } 6880 } 6881 } 6882 6883 return 0; 6884 } 6885 6886 int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp) 6887 { 6888 Error *local_err = NULL; 6889 IO_CODE(); 6890 6891 assert(!(bs->open_flags & BDRV_O_INACTIVE)); 6892 assert_bdrv_graph_readable(); 6893 6894 if (bs->drv->bdrv_co_invalidate_cache) { 6895 bs->drv->bdrv_co_invalidate_cache(bs, &local_err); 6896 if (local_err) { 6897 error_propagate(errp, local_err); 6898 return -EINVAL; 6899 } 6900 } 6901 6902 return 0; 6903 } 6904 6905 void bdrv_activate_all(Error **errp) 6906 { 6907 BlockDriverState *bs; 6908 BdrvNextIterator it; 6909 6910 GLOBAL_STATE_CODE(); 6911 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6912 6913 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 6914 int ret; 6915 6916 ret = bdrv_activate(bs, errp); 6917 if (ret < 0) { 6918 bdrv_next_cleanup(&it); 6919 return; 6920 } 6921 } 6922 } 6923 6924 static bool GRAPH_RDLOCK 6925 bdrv_has_bds_parent(BlockDriverState *bs, bool only_active) 6926 { 6927 BdrvChild *parent; 6928 GLOBAL_STATE_CODE(); 6929 6930 QLIST_FOREACH(parent, &bs->parents, next_parent) { 6931 if (parent->klass->parent_is_bds) { 6932 BlockDriverState *parent_bs = parent->opaque; 6933 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) { 6934 return true; 6935 } 6936 } 6937 } 6938 6939 return false; 6940 } 6941 6942 static int GRAPH_RDLOCK bdrv_inactivate_recurse(BlockDriverState *bs) 6943 { 6944 BdrvChild *child, *parent; 6945 int ret; 6946 uint64_t cumulative_perms, cumulative_shared_perms; 6947 6948 GLOBAL_STATE_CODE(); 6949 6950 if (!bs->drv) { 6951 return -ENOMEDIUM; 6952 } 6953 6954 /* Make sure that we don't inactivate a child before its parent. 6955 * It will be covered by recursion from the yet active parent. */ 6956 if (bdrv_has_bds_parent(bs, true)) { 6957 return 0; 6958 } 6959 6960 assert(!(bs->open_flags & BDRV_O_INACTIVE)); 6961 6962 /* Inactivate this node */ 6963 if (bs->drv->bdrv_inactivate) { 6964 ret = bs->drv->bdrv_inactivate(bs); 6965 if (ret < 0) { 6966 return ret; 6967 } 6968 } 6969 6970 QLIST_FOREACH(parent, &bs->parents, next_parent) { 6971 if (parent->klass->inactivate) { 6972 ret = parent->klass->inactivate(parent); 6973 if (ret < 0) { 6974 return ret; 6975 } 6976 } 6977 } 6978 6979 bdrv_get_cumulative_perm(bs, &cumulative_perms, 6980 &cumulative_shared_perms); 6981 if (cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) { 6982 /* Our inactive parents still need write access. Inactivation failed. */ 6983 return -EPERM; 6984 } 6985 6986 bs->open_flags |= BDRV_O_INACTIVE; 6987 6988 /* 6989 * Update permissions, they may differ for inactive nodes. 6990 * We only tried to loosen restrictions, so errors are not fatal, ignore 6991 * them. 6992 */ 6993 bdrv_refresh_perms(bs, NULL, NULL); 6994 6995 /* Recursively inactivate children */ 6996 QLIST_FOREACH(child, &bs->children, next) { 6997 ret = bdrv_inactivate_recurse(child->bs); 6998 if (ret < 0) { 6999 return ret; 7000 } 7001 } 7002 7003 return 0; 7004 } 7005 7006 int bdrv_inactivate_all(void) 7007 { 7008 BlockDriverState *bs = NULL; 7009 BdrvNextIterator it; 7010 int ret = 0; 7011 7012 GLOBAL_STATE_CODE(); 7013 GRAPH_RDLOCK_GUARD_MAINLOOP(); 7014 7015 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 7016 /* Nodes with BDS parents are covered by recursion from the last 7017 * parent that gets inactivated. Don't inactivate them a second 7018 * time if that has already happened. */ 7019 if (bdrv_has_bds_parent(bs, false)) { 7020 continue; 7021 } 7022 ret = bdrv_inactivate_recurse(bs); 7023 if (ret < 0) { 7024 bdrv_next_cleanup(&it); 7025 break; 7026 } 7027 } 7028 7029 return ret; 7030 } 7031 7032 /**************************************************************/ 7033 /* removable device support */ 7034 7035 /** 7036 * Return TRUE if the media is present 7037 */ 7038 bool coroutine_fn bdrv_co_is_inserted(BlockDriverState *bs) 7039 { 7040 BlockDriver *drv = bs->drv; 7041 BdrvChild *child; 7042 IO_CODE(); 7043 assert_bdrv_graph_readable(); 7044 7045 if (!drv) { 7046 return false; 7047 } 7048 if (drv->bdrv_co_is_inserted) { 7049 return drv->bdrv_co_is_inserted(bs); 7050 } 7051 QLIST_FOREACH(child, &bs->children, next) { 7052 if (!bdrv_co_is_inserted(child->bs)) { 7053 return false; 7054 } 7055 } 7056 return true; 7057 } 7058 7059 /** 7060 * If eject_flag is TRUE, eject the media. Otherwise, close the tray 7061 */ 7062 void coroutine_fn bdrv_co_eject(BlockDriverState *bs, bool eject_flag) 7063 { 7064 BlockDriver *drv = bs->drv; 7065 IO_CODE(); 7066 assert_bdrv_graph_readable(); 7067 7068 if (drv && drv->bdrv_co_eject) { 7069 drv->bdrv_co_eject(bs, eject_flag); 7070 } 7071 } 7072 7073 /** 7074 * Lock or unlock the media (if it is locked, the user won't be able 7075 * to eject it manually). 7076 */ 7077 void coroutine_fn bdrv_co_lock_medium(BlockDriverState *bs, bool locked) 7078 { 7079 BlockDriver *drv = bs->drv; 7080 IO_CODE(); 7081 assert_bdrv_graph_readable(); 7082 trace_bdrv_lock_medium(bs, locked); 7083 7084 if (drv && drv->bdrv_co_lock_medium) { 7085 drv->bdrv_co_lock_medium(bs, locked); 7086 } 7087 } 7088 7089 /* Get a reference to bs */ 7090 void bdrv_ref(BlockDriverState *bs) 7091 { 7092 GLOBAL_STATE_CODE(); 7093 bs->refcnt++; 7094 } 7095 7096 /* Release a previously grabbed reference to bs. 7097 * If after releasing, reference count is zero, the BlockDriverState is 7098 * deleted. */ 7099 void bdrv_unref(BlockDriverState *bs) 7100 { 7101 GLOBAL_STATE_CODE(); 7102 if (!bs) { 7103 return; 7104 } 7105 assert(bs->refcnt > 0); 7106 if (--bs->refcnt == 0) { 7107 bdrv_delete(bs); 7108 } 7109 } 7110 7111 static void bdrv_schedule_unref_bh(void *opaque) 7112 { 7113 BlockDriverState *bs = opaque; 7114 7115 bdrv_unref(bs); 7116 } 7117 7118 /* 7119 * Release a BlockDriverState reference while holding the graph write lock. 7120 * 7121 * Calling bdrv_unref() directly is forbidden while holding the graph lock 7122 * because bdrv_close() both involves polling and taking the graph lock 7123 * internally. bdrv_schedule_unref() instead delays decreasing the refcount and 7124 * possibly closing @bs until the graph lock is released. 7125 */ 7126 void bdrv_schedule_unref(BlockDriverState *bs) 7127 { 7128 if (!bs) { 7129 return; 7130 } 7131 aio_bh_schedule_oneshot(qemu_get_aio_context(), bdrv_schedule_unref_bh, bs); 7132 } 7133 7134 struct BdrvOpBlocker { 7135 Error *reason; 7136 QLIST_ENTRY(BdrvOpBlocker) list; 7137 }; 7138 7139 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp) 7140 { 7141 BdrvOpBlocker *blocker; 7142 GLOBAL_STATE_CODE(); 7143 7144 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 7145 if (!QLIST_EMPTY(&bs->op_blockers[op])) { 7146 blocker = QLIST_FIRST(&bs->op_blockers[op]); 7147 error_propagate_prepend(errp, error_copy(blocker->reason), 7148 "Node '%s' is busy: ", 7149 bdrv_get_device_or_node_name(bs)); 7150 return true; 7151 } 7152 return false; 7153 } 7154 7155 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason) 7156 { 7157 BdrvOpBlocker *blocker; 7158 GLOBAL_STATE_CODE(); 7159 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 7160 7161 blocker = g_new0(BdrvOpBlocker, 1); 7162 blocker->reason = reason; 7163 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); 7164 } 7165 7166 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason) 7167 { 7168 BdrvOpBlocker *blocker, *next; 7169 GLOBAL_STATE_CODE(); 7170 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 7171 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) { 7172 if (blocker->reason == reason) { 7173 QLIST_REMOVE(blocker, list); 7174 g_free(blocker); 7175 } 7176 } 7177 } 7178 7179 void bdrv_op_block_all(BlockDriverState *bs, Error *reason) 7180 { 7181 int i; 7182 GLOBAL_STATE_CODE(); 7183 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 7184 bdrv_op_block(bs, i, reason); 7185 } 7186 } 7187 7188 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason) 7189 { 7190 int i; 7191 GLOBAL_STATE_CODE(); 7192 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 7193 bdrv_op_unblock(bs, i, reason); 7194 } 7195 } 7196 7197 bool bdrv_op_blocker_is_empty(BlockDriverState *bs) 7198 { 7199 int i; 7200 GLOBAL_STATE_CODE(); 7201 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 7202 if (!QLIST_EMPTY(&bs->op_blockers[i])) { 7203 return false; 7204 } 7205 } 7206 return true; 7207 } 7208 7209 /* 7210 * Must not be called while holding the lock of an AioContext other than the 7211 * current one. 7212 */ 7213 void bdrv_img_create(const char *filename, const char *fmt, 7214 const char *base_filename, const char *base_fmt, 7215 char *options, uint64_t img_size, int flags, bool quiet, 7216 Error **errp) 7217 { 7218 QemuOptsList *create_opts = NULL; 7219 QemuOpts *opts = NULL; 7220 const char *backing_fmt, *backing_file; 7221 int64_t size; 7222 BlockDriver *drv, *proto_drv; 7223 Error *local_err = NULL; 7224 int ret = 0; 7225 7226 GLOBAL_STATE_CODE(); 7227 7228 /* Find driver and parse its options */ 7229 drv = bdrv_find_format(fmt); 7230 if (!drv) { 7231 error_setg(errp, "Unknown file format '%s'", fmt); 7232 return; 7233 } 7234 7235 proto_drv = bdrv_find_protocol(filename, true, errp); 7236 if (!proto_drv) { 7237 return; 7238 } 7239 7240 if (!drv->create_opts) { 7241 error_setg(errp, "Format driver '%s' does not support image creation", 7242 drv->format_name); 7243 return; 7244 } 7245 7246 if (!proto_drv->create_opts) { 7247 error_setg(errp, "Protocol driver '%s' does not support image creation", 7248 proto_drv->format_name); 7249 return; 7250 } 7251 7252 /* Create parameter list */ 7253 create_opts = qemu_opts_append(create_opts, drv->create_opts); 7254 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts); 7255 7256 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort); 7257 7258 /* Parse -o options */ 7259 if (options) { 7260 if (!qemu_opts_do_parse(opts, options, NULL, errp)) { 7261 goto out; 7262 } 7263 } 7264 7265 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) { 7266 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort); 7267 } else if (img_size != UINT64_C(-1)) { 7268 error_setg(errp, "The image size must be specified only once"); 7269 goto out; 7270 } 7271 7272 if (base_filename) { 7273 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename, 7274 NULL)) { 7275 error_setg(errp, "Backing file not supported for file format '%s'", 7276 fmt); 7277 goto out; 7278 } 7279 } 7280 7281 if (base_fmt) { 7282 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) { 7283 error_setg(errp, "Backing file format not supported for file " 7284 "format '%s'", fmt); 7285 goto out; 7286 } 7287 } 7288 7289 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE); 7290 if (backing_file) { 7291 if (!strcmp(filename, backing_file)) { 7292 error_setg(errp, "Error: Trying to create an image with the " 7293 "same filename as the backing file"); 7294 goto out; 7295 } 7296 if (backing_file[0] == '\0') { 7297 error_setg(errp, "Expected backing file name, got empty string"); 7298 goto out; 7299 } 7300 } 7301 7302 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT); 7303 7304 /* The size for the image must always be specified, unless we have a backing 7305 * file and we have not been forbidden from opening it. */ 7306 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size); 7307 if (backing_file && !(flags & BDRV_O_NO_BACKING)) { 7308 BlockDriverState *bs; 7309 char *full_backing; 7310 int back_flags; 7311 QDict *backing_options = NULL; 7312 7313 full_backing = 7314 bdrv_get_full_backing_filename_from_filename(filename, backing_file, 7315 &local_err); 7316 if (local_err) { 7317 goto out; 7318 } 7319 assert(full_backing); 7320 7321 /* 7322 * No need to do I/O here, which allows us to open encrypted 7323 * backing images without needing the secret 7324 */ 7325 back_flags = flags; 7326 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING); 7327 back_flags |= BDRV_O_NO_IO; 7328 7329 backing_options = qdict_new(); 7330 if (backing_fmt) { 7331 qdict_put_str(backing_options, "driver", backing_fmt); 7332 } 7333 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true); 7334 7335 bs = bdrv_open(full_backing, NULL, backing_options, back_flags, 7336 &local_err); 7337 g_free(full_backing); 7338 if (!bs) { 7339 error_append_hint(&local_err, "Could not open backing image.\n"); 7340 goto out; 7341 } else { 7342 if (!backing_fmt) { 7343 error_setg(&local_err, 7344 "Backing file specified without backing format"); 7345 error_append_hint(&local_err, "Detected format of %s.\n", 7346 bs->drv->format_name); 7347 goto out; 7348 } 7349 if (size == -1) { 7350 /* Opened BS, have no size */ 7351 size = bdrv_getlength(bs); 7352 if (size < 0) { 7353 error_setg_errno(errp, -size, "Could not get size of '%s'", 7354 backing_file); 7355 bdrv_unref(bs); 7356 goto out; 7357 } 7358 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort); 7359 } 7360 bdrv_unref(bs); 7361 } 7362 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */ 7363 } else if (backing_file && !backing_fmt) { 7364 error_setg(&local_err, 7365 "Backing file specified without backing format"); 7366 goto out; 7367 } 7368 7369 if (size == -1) { 7370 error_setg(errp, "Image creation needs a size parameter"); 7371 goto out; 7372 } 7373 7374 if (!quiet) { 7375 printf("Formatting '%s', fmt=%s ", filename, fmt); 7376 qemu_opts_print(opts, " "); 7377 puts(""); 7378 fflush(stdout); 7379 } 7380 7381 ret = bdrv_create(drv, filename, opts, &local_err); 7382 7383 if (ret == -EFBIG) { 7384 /* This is generally a better message than whatever the driver would 7385 * deliver (especially because of the cluster_size_hint), since that 7386 * is most probably not much different from "image too large". */ 7387 const char *cluster_size_hint = ""; 7388 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) { 7389 cluster_size_hint = " (try using a larger cluster size)"; 7390 } 7391 error_setg(errp, "The image size is too large for file format '%s'" 7392 "%s", fmt, cluster_size_hint); 7393 error_free(local_err); 7394 local_err = NULL; 7395 } 7396 7397 out: 7398 qemu_opts_del(opts); 7399 qemu_opts_free(create_opts); 7400 error_propagate(errp, local_err); 7401 } 7402 7403 AioContext *bdrv_get_aio_context(BlockDriverState *bs) 7404 { 7405 IO_CODE(); 7406 return bs ? bs->aio_context : qemu_get_aio_context(); 7407 } 7408 7409 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs) 7410 { 7411 Coroutine *self = qemu_coroutine_self(); 7412 AioContext *old_ctx = qemu_coroutine_get_aio_context(self); 7413 AioContext *new_ctx; 7414 IO_CODE(); 7415 7416 /* 7417 * Increase bs->in_flight to ensure that this operation is completed before 7418 * moving the node to a different AioContext. Read new_ctx only afterwards. 7419 */ 7420 bdrv_inc_in_flight(bs); 7421 7422 new_ctx = bdrv_get_aio_context(bs); 7423 aio_co_reschedule_self(new_ctx); 7424 return old_ctx; 7425 } 7426 7427 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx) 7428 { 7429 IO_CODE(); 7430 aio_co_reschedule_self(old_ctx); 7431 bdrv_dec_in_flight(bs); 7432 } 7433 7434 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban) 7435 { 7436 GLOBAL_STATE_CODE(); 7437 QLIST_REMOVE(ban, list); 7438 g_free(ban); 7439 } 7440 7441 static void bdrv_detach_aio_context(BlockDriverState *bs) 7442 { 7443 BdrvAioNotifier *baf, *baf_tmp; 7444 7445 assert(!bs->walking_aio_notifiers); 7446 GLOBAL_STATE_CODE(); 7447 bs->walking_aio_notifiers = true; 7448 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) { 7449 if (baf->deleted) { 7450 bdrv_do_remove_aio_context_notifier(baf); 7451 } else { 7452 baf->detach_aio_context(baf->opaque); 7453 } 7454 } 7455 /* Never mind iterating again to check for ->deleted. bdrv_close() will 7456 * remove remaining aio notifiers if we aren't called again. 7457 */ 7458 bs->walking_aio_notifiers = false; 7459 7460 if (bs->drv && bs->drv->bdrv_detach_aio_context) { 7461 bs->drv->bdrv_detach_aio_context(bs); 7462 } 7463 7464 bs->aio_context = NULL; 7465 } 7466 7467 static void bdrv_attach_aio_context(BlockDriverState *bs, 7468 AioContext *new_context) 7469 { 7470 BdrvAioNotifier *ban, *ban_tmp; 7471 GLOBAL_STATE_CODE(); 7472 7473 bs->aio_context = new_context; 7474 7475 if (bs->drv && bs->drv->bdrv_attach_aio_context) { 7476 bs->drv->bdrv_attach_aio_context(bs, new_context); 7477 } 7478 7479 assert(!bs->walking_aio_notifiers); 7480 bs->walking_aio_notifiers = true; 7481 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) { 7482 if (ban->deleted) { 7483 bdrv_do_remove_aio_context_notifier(ban); 7484 } else { 7485 ban->attached_aio_context(new_context, ban->opaque); 7486 } 7487 } 7488 bs->walking_aio_notifiers = false; 7489 } 7490 7491 typedef struct BdrvStateSetAioContext { 7492 AioContext *new_ctx; 7493 BlockDriverState *bs; 7494 } BdrvStateSetAioContext; 7495 7496 static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx, 7497 GHashTable *visited, 7498 Transaction *tran, 7499 Error **errp) 7500 { 7501 GLOBAL_STATE_CODE(); 7502 if (g_hash_table_contains(visited, c)) { 7503 return true; 7504 } 7505 g_hash_table_add(visited, c); 7506 7507 /* 7508 * A BdrvChildClass that doesn't handle AioContext changes cannot 7509 * tolerate any AioContext changes 7510 */ 7511 if (!c->klass->change_aio_ctx) { 7512 char *user = bdrv_child_user_desc(c); 7513 error_setg(errp, "Changing iothreads is not supported by %s", user); 7514 g_free(user); 7515 return false; 7516 } 7517 if (!c->klass->change_aio_ctx(c, ctx, visited, tran, errp)) { 7518 assert(!errp || *errp); 7519 return false; 7520 } 7521 return true; 7522 } 7523 7524 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx, 7525 GHashTable *visited, Transaction *tran, 7526 Error **errp) 7527 { 7528 GLOBAL_STATE_CODE(); 7529 if (g_hash_table_contains(visited, c)) { 7530 return true; 7531 } 7532 g_hash_table_add(visited, c); 7533 return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp); 7534 } 7535 7536 static void bdrv_set_aio_context_clean(void *opaque) 7537 { 7538 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque; 7539 BlockDriverState *bs = (BlockDriverState *) state->bs; 7540 7541 /* Paired with bdrv_drained_begin in bdrv_change_aio_context() */ 7542 bdrv_drained_end(bs); 7543 7544 g_free(state); 7545 } 7546 7547 static void bdrv_set_aio_context_commit(void *opaque) 7548 { 7549 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque; 7550 BlockDriverState *bs = (BlockDriverState *) state->bs; 7551 AioContext *new_context = state->new_ctx; 7552 7553 bdrv_detach_aio_context(bs); 7554 bdrv_attach_aio_context(bs, new_context); 7555 } 7556 7557 static TransactionActionDrv set_aio_context = { 7558 .commit = bdrv_set_aio_context_commit, 7559 .clean = bdrv_set_aio_context_clean, 7560 }; 7561 7562 /* 7563 * Changes the AioContext used for fd handlers, timers, and BHs by this 7564 * BlockDriverState and all its children and parents. 7565 * 7566 * Must be called from the main AioContext. 7567 * 7568 * The caller must own the AioContext lock for the old AioContext of bs, but it 7569 * must not own the AioContext lock for new_context (unless new_context is the 7570 * same as the current context of bs). 7571 * 7572 * @visited will accumulate all visited BdrvChild objects. The caller is 7573 * responsible for freeing the list afterwards. 7574 */ 7575 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx, 7576 GHashTable *visited, Transaction *tran, 7577 Error **errp) 7578 { 7579 BdrvChild *c; 7580 BdrvStateSetAioContext *state; 7581 7582 GLOBAL_STATE_CODE(); 7583 7584 if (bdrv_get_aio_context(bs) == ctx) { 7585 return true; 7586 } 7587 7588 bdrv_graph_rdlock_main_loop(); 7589 QLIST_FOREACH(c, &bs->parents, next_parent) { 7590 if (!bdrv_parent_change_aio_context(c, ctx, visited, tran, errp)) { 7591 bdrv_graph_rdunlock_main_loop(); 7592 return false; 7593 } 7594 } 7595 7596 QLIST_FOREACH(c, &bs->children, next) { 7597 if (!bdrv_child_change_aio_context(c, ctx, visited, tran, errp)) { 7598 bdrv_graph_rdunlock_main_loop(); 7599 return false; 7600 } 7601 } 7602 bdrv_graph_rdunlock_main_loop(); 7603 7604 state = g_new(BdrvStateSetAioContext, 1); 7605 *state = (BdrvStateSetAioContext) { 7606 .new_ctx = ctx, 7607 .bs = bs, 7608 }; 7609 7610 /* Paired with bdrv_drained_end in bdrv_set_aio_context_clean() */ 7611 bdrv_drained_begin(bs); 7612 7613 tran_add(tran, &set_aio_context, state); 7614 7615 return true; 7616 } 7617 7618 /* 7619 * Change bs's and recursively all of its parents' and children's AioContext 7620 * to the given new context, returning an error if that isn't possible. 7621 * 7622 * If ignore_child is not NULL, that child (and its subgraph) will not 7623 * be touched. 7624 * 7625 * This function still requires the caller to take the bs current 7626 * AioContext lock, otherwise draining will fail since AIO_WAIT_WHILE 7627 * assumes the lock is always held if bs is in another AioContext. 7628 * For the same reason, it temporarily also holds the new AioContext, since 7629 * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too. 7630 * Therefore the new AioContext lock must not be taken by the caller. 7631 */ 7632 int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, 7633 BdrvChild *ignore_child, Error **errp) 7634 { 7635 Transaction *tran; 7636 GHashTable *visited; 7637 int ret; 7638 GLOBAL_STATE_CODE(); 7639 7640 /* 7641 * Recursion phase: go through all nodes of the graph. 7642 * Take care of checking that all nodes support changing AioContext 7643 * and drain them, building a linear list of callbacks to run if everything 7644 * is successful (the transaction itself). 7645 */ 7646 tran = tran_new(); 7647 visited = g_hash_table_new(NULL, NULL); 7648 if (ignore_child) { 7649 g_hash_table_add(visited, ignore_child); 7650 } 7651 ret = bdrv_change_aio_context(bs, ctx, visited, tran, errp); 7652 g_hash_table_destroy(visited); 7653 7654 /* 7655 * Linear phase: go through all callbacks collected in the transaction. 7656 * Run all callbacks collected in the recursion to switch all nodes 7657 * AioContext lock (transaction commit), or undo all changes done in the 7658 * recursion (transaction abort). 7659 */ 7660 7661 if (!ret) { 7662 /* Just run clean() callbacks. No AioContext changed. */ 7663 tran_abort(tran); 7664 return -EPERM; 7665 } 7666 7667 tran_commit(tran); 7668 return 0; 7669 } 7670 7671 void bdrv_add_aio_context_notifier(BlockDriverState *bs, 7672 void (*attached_aio_context)(AioContext *new_context, void *opaque), 7673 void (*detach_aio_context)(void *opaque), void *opaque) 7674 { 7675 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1); 7676 *ban = (BdrvAioNotifier){ 7677 .attached_aio_context = attached_aio_context, 7678 .detach_aio_context = detach_aio_context, 7679 .opaque = opaque 7680 }; 7681 GLOBAL_STATE_CODE(); 7682 7683 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list); 7684 } 7685 7686 void bdrv_remove_aio_context_notifier(BlockDriverState *bs, 7687 void (*attached_aio_context)(AioContext *, 7688 void *), 7689 void (*detach_aio_context)(void *), 7690 void *opaque) 7691 { 7692 BdrvAioNotifier *ban, *ban_next; 7693 GLOBAL_STATE_CODE(); 7694 7695 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 7696 if (ban->attached_aio_context == attached_aio_context && 7697 ban->detach_aio_context == detach_aio_context && 7698 ban->opaque == opaque && 7699 ban->deleted == false) 7700 { 7701 if (bs->walking_aio_notifiers) { 7702 ban->deleted = true; 7703 } else { 7704 bdrv_do_remove_aio_context_notifier(ban); 7705 } 7706 return; 7707 } 7708 } 7709 7710 abort(); 7711 } 7712 7713 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts, 7714 BlockDriverAmendStatusCB *status_cb, void *cb_opaque, 7715 bool force, 7716 Error **errp) 7717 { 7718 GLOBAL_STATE_CODE(); 7719 if (!bs->drv) { 7720 error_setg(errp, "Node is ejected"); 7721 return -ENOMEDIUM; 7722 } 7723 if (!bs->drv->bdrv_amend_options) { 7724 error_setg(errp, "Block driver '%s' does not support option amendment", 7725 bs->drv->format_name); 7726 return -ENOTSUP; 7727 } 7728 return bs->drv->bdrv_amend_options(bs, opts, status_cb, 7729 cb_opaque, force, errp); 7730 } 7731 7732 /* 7733 * This function checks whether the given @to_replace is allowed to be 7734 * replaced by a node that always shows the same data as @bs. This is 7735 * used for example to verify whether the mirror job can replace 7736 * @to_replace by the target mirrored from @bs. 7737 * To be replaceable, @bs and @to_replace may either be guaranteed to 7738 * always show the same data (because they are only connected through 7739 * filters), or some driver may allow replacing one of its children 7740 * because it can guarantee that this child's data is not visible at 7741 * all (for example, for dissenting quorum children that have no other 7742 * parents). 7743 */ 7744 bool bdrv_recurse_can_replace(BlockDriverState *bs, 7745 BlockDriverState *to_replace) 7746 { 7747 BlockDriverState *filtered; 7748 7749 GLOBAL_STATE_CODE(); 7750 7751 if (!bs || !bs->drv) { 7752 return false; 7753 } 7754 7755 if (bs == to_replace) { 7756 return true; 7757 } 7758 7759 /* See what the driver can do */ 7760 if (bs->drv->bdrv_recurse_can_replace) { 7761 return bs->drv->bdrv_recurse_can_replace(bs, to_replace); 7762 } 7763 7764 /* For filters without an own implementation, we can recurse on our own */ 7765 filtered = bdrv_filter_bs(bs); 7766 if (filtered) { 7767 return bdrv_recurse_can_replace(filtered, to_replace); 7768 } 7769 7770 /* Safe default */ 7771 return false; 7772 } 7773 7774 /* 7775 * Check whether the given @node_name can be replaced by a node that 7776 * has the same data as @parent_bs. If so, return @node_name's BDS; 7777 * NULL otherwise. 7778 * 7779 * @node_name must be a (recursive) *child of @parent_bs (or this 7780 * function will return NULL). 7781 * 7782 * The result (whether the node can be replaced or not) is only valid 7783 * for as long as no graph or permission changes occur. 7784 */ 7785 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs, 7786 const char *node_name, Error **errp) 7787 { 7788 BlockDriverState *to_replace_bs = bdrv_find_node(node_name); 7789 7790 GLOBAL_STATE_CODE(); 7791 7792 if (!to_replace_bs) { 7793 error_setg(errp, "Failed to find node with node-name='%s'", node_name); 7794 return NULL; 7795 } 7796 7797 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) { 7798 return NULL; 7799 } 7800 7801 /* We don't want arbitrary node of the BDS chain to be replaced only the top 7802 * most non filter in order to prevent data corruption. 7803 * Another benefit is that this tests exclude backing files which are 7804 * blocked by the backing blockers. 7805 */ 7806 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) { 7807 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', " 7808 "because it cannot be guaranteed that doing so would not " 7809 "lead to an abrupt change of visible data", 7810 node_name, parent_bs->node_name); 7811 return NULL; 7812 } 7813 7814 return to_replace_bs; 7815 } 7816 7817 /** 7818 * Iterates through the list of runtime option keys that are said to 7819 * be "strong" for a BDS. An option is called "strong" if it changes 7820 * a BDS's data. For example, the null block driver's "size" and 7821 * "read-zeroes" options are strong, but its "latency-ns" option is 7822 * not. 7823 * 7824 * If a key returned by this function ends with a dot, all options 7825 * starting with that prefix are strong. 7826 */ 7827 static const char *const *strong_options(BlockDriverState *bs, 7828 const char *const *curopt) 7829 { 7830 static const char *const global_options[] = { 7831 "driver", "filename", NULL 7832 }; 7833 7834 if (!curopt) { 7835 return &global_options[0]; 7836 } 7837 7838 curopt++; 7839 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) { 7840 curopt = bs->drv->strong_runtime_opts; 7841 } 7842 7843 return (curopt && *curopt) ? curopt : NULL; 7844 } 7845 7846 /** 7847 * Copies all strong runtime options from bs->options to the given 7848 * QDict. The set of strong option keys is determined by invoking 7849 * strong_options(). 7850 * 7851 * Returns true iff any strong option was present in bs->options (and 7852 * thus copied to the target QDict) with the exception of "filename" 7853 * and "driver". The caller is expected to use this value to decide 7854 * whether the existence of strong options prevents the generation of 7855 * a plain filename. 7856 */ 7857 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs) 7858 { 7859 bool found_any = false; 7860 const char *const *option_name = NULL; 7861 7862 if (!bs->drv) { 7863 return false; 7864 } 7865 7866 while ((option_name = strong_options(bs, option_name))) { 7867 bool option_given = false; 7868 7869 assert(strlen(*option_name) > 0); 7870 if ((*option_name)[strlen(*option_name) - 1] != '.') { 7871 QObject *entry = qdict_get(bs->options, *option_name); 7872 if (!entry) { 7873 continue; 7874 } 7875 7876 qdict_put_obj(d, *option_name, qobject_ref(entry)); 7877 option_given = true; 7878 } else { 7879 const QDictEntry *entry; 7880 for (entry = qdict_first(bs->options); entry; 7881 entry = qdict_next(bs->options, entry)) 7882 { 7883 if (strstart(qdict_entry_key(entry), *option_name, NULL)) { 7884 qdict_put_obj(d, qdict_entry_key(entry), 7885 qobject_ref(qdict_entry_value(entry))); 7886 option_given = true; 7887 } 7888 } 7889 } 7890 7891 /* While "driver" and "filename" need to be included in a JSON filename, 7892 * their existence does not prohibit generation of a plain filename. */ 7893 if (!found_any && option_given && 7894 strcmp(*option_name, "driver") && strcmp(*option_name, "filename")) 7895 { 7896 found_any = true; 7897 } 7898 } 7899 7900 if (!qdict_haskey(d, "driver")) { 7901 /* Drivers created with bdrv_new_open_driver() may not have a 7902 * @driver option. Add it here. */ 7903 qdict_put_str(d, "driver", bs->drv->format_name); 7904 } 7905 7906 return found_any; 7907 } 7908 7909 /* Note: This function may return false positives; it may return true 7910 * even if opening the backing file specified by bs's image header 7911 * would result in exactly bs->backing. */ 7912 static bool GRAPH_RDLOCK bdrv_backing_overridden(BlockDriverState *bs) 7913 { 7914 GLOBAL_STATE_CODE(); 7915 if (bs->backing) { 7916 return strcmp(bs->auto_backing_file, 7917 bs->backing->bs->filename); 7918 } else { 7919 /* No backing BDS, so if the image header reports any backing 7920 * file, it must have been suppressed */ 7921 return bs->auto_backing_file[0] != '\0'; 7922 } 7923 } 7924 7925 /* Updates the following BDS fields: 7926 * - exact_filename: A filename which may be used for opening a block device 7927 * which (mostly) equals the given BDS (even without any 7928 * other options; so reading and writing must return the same 7929 * results, but caching etc. may be different) 7930 * - full_open_options: Options which, when given when opening a block device 7931 * (without a filename), result in a BDS (mostly) 7932 * equalling the given one 7933 * - filename: If exact_filename is set, it is copied here. Otherwise, 7934 * full_open_options is converted to a JSON object, prefixed with 7935 * "json:" (for use through the JSON pseudo protocol) and put here. 7936 */ 7937 void bdrv_refresh_filename(BlockDriverState *bs) 7938 { 7939 BlockDriver *drv = bs->drv; 7940 BdrvChild *child; 7941 BlockDriverState *primary_child_bs; 7942 QDict *opts; 7943 bool backing_overridden; 7944 bool generate_json_filename; /* Whether our default implementation should 7945 fill exact_filename (false) or not (true) */ 7946 7947 GLOBAL_STATE_CODE(); 7948 7949 if (!drv) { 7950 return; 7951 } 7952 7953 /* This BDS's file name may depend on any of its children's file names, so 7954 * refresh those first */ 7955 QLIST_FOREACH(child, &bs->children, next) { 7956 bdrv_refresh_filename(child->bs); 7957 } 7958 7959 if (bs->implicit) { 7960 /* For implicit nodes, just copy everything from the single child */ 7961 child = QLIST_FIRST(&bs->children); 7962 assert(QLIST_NEXT(child, next) == NULL); 7963 7964 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 7965 child->bs->exact_filename); 7966 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename); 7967 7968 qobject_unref(bs->full_open_options); 7969 bs->full_open_options = qobject_ref(child->bs->full_open_options); 7970 7971 return; 7972 } 7973 7974 backing_overridden = bdrv_backing_overridden(bs); 7975 7976 if (bs->open_flags & BDRV_O_NO_IO) { 7977 /* Without I/O, the backing file does not change anything. 7978 * Therefore, in such a case (primarily qemu-img), we can 7979 * pretend the backing file has not been overridden even if 7980 * it technically has been. */ 7981 backing_overridden = false; 7982 } 7983 7984 /* Gather the options QDict */ 7985 opts = qdict_new(); 7986 generate_json_filename = append_strong_runtime_options(opts, bs); 7987 generate_json_filename |= backing_overridden; 7988 7989 if (drv->bdrv_gather_child_options) { 7990 /* Some block drivers may not want to present all of their children's 7991 * options, or name them differently from BdrvChild.name */ 7992 drv->bdrv_gather_child_options(bs, opts, backing_overridden); 7993 } else { 7994 QLIST_FOREACH(child, &bs->children, next) { 7995 if (child == bs->backing && !backing_overridden) { 7996 /* We can skip the backing BDS if it has not been overridden */ 7997 continue; 7998 } 7999 8000 qdict_put(opts, child->name, 8001 qobject_ref(child->bs->full_open_options)); 8002 } 8003 8004 if (backing_overridden && !bs->backing) { 8005 /* Force no backing file */ 8006 qdict_put_null(opts, "backing"); 8007 } 8008 } 8009 8010 qobject_unref(bs->full_open_options); 8011 bs->full_open_options = opts; 8012 8013 primary_child_bs = bdrv_primary_bs(bs); 8014 8015 if (drv->bdrv_refresh_filename) { 8016 /* Obsolete information is of no use here, so drop the old file name 8017 * information before refreshing it */ 8018 bs->exact_filename[0] = '\0'; 8019 8020 drv->bdrv_refresh_filename(bs); 8021 } else if (primary_child_bs) { 8022 /* 8023 * Try to reconstruct valid information from the underlying 8024 * file -- this only works for format nodes (filter nodes 8025 * cannot be probed and as such must be selected by the user 8026 * either through an options dict, or through a special 8027 * filename which the filter driver must construct in its 8028 * .bdrv_refresh_filename() implementation). 8029 */ 8030 8031 bs->exact_filename[0] = '\0'; 8032 8033 /* 8034 * We can use the underlying file's filename if: 8035 * - it has a filename, 8036 * - the current BDS is not a filter, 8037 * - the file is a protocol BDS, and 8038 * - opening that file (as this BDS's format) will automatically create 8039 * the BDS tree we have right now, that is: 8040 * - the user did not significantly change this BDS's behavior with 8041 * some explicit (strong) options 8042 * - no non-file child of this BDS has been overridden by the user 8043 * Both of these conditions are represented by generate_json_filename. 8044 */ 8045 if (primary_child_bs->exact_filename[0] && 8046 primary_child_bs->drv->bdrv_file_open && 8047 !drv->is_filter && !generate_json_filename) 8048 { 8049 strcpy(bs->exact_filename, primary_child_bs->exact_filename); 8050 } 8051 } 8052 8053 if (bs->exact_filename[0]) { 8054 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename); 8055 } else { 8056 GString *json = qobject_to_json(QOBJECT(bs->full_open_options)); 8057 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s", 8058 json->str) >= sizeof(bs->filename)) { 8059 /* Give user a hint if we truncated things. */ 8060 strcpy(bs->filename + sizeof(bs->filename) - 4, "..."); 8061 } 8062 g_string_free(json, true); 8063 } 8064 } 8065 8066 char *bdrv_dirname(BlockDriverState *bs, Error **errp) 8067 { 8068 BlockDriver *drv = bs->drv; 8069 BlockDriverState *child_bs; 8070 8071 GLOBAL_STATE_CODE(); 8072 8073 if (!drv) { 8074 error_setg(errp, "Node '%s' is ejected", bs->node_name); 8075 return NULL; 8076 } 8077 8078 if (drv->bdrv_dirname) { 8079 return drv->bdrv_dirname(bs, errp); 8080 } 8081 8082 child_bs = bdrv_primary_bs(bs); 8083 if (child_bs) { 8084 return bdrv_dirname(child_bs, errp); 8085 } 8086 8087 bdrv_refresh_filename(bs); 8088 if (bs->exact_filename[0] != '\0') { 8089 return path_combine(bs->exact_filename, ""); 8090 } 8091 8092 error_setg(errp, "Cannot generate a base directory for %s nodes", 8093 drv->format_name); 8094 return NULL; 8095 } 8096 8097 /* 8098 * Hot add/remove a BDS's child. So the user can take a child offline when 8099 * it is broken and take a new child online 8100 */ 8101 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, 8102 Error **errp) 8103 { 8104 GLOBAL_STATE_CODE(); 8105 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) { 8106 error_setg(errp, "The node %s does not support adding a child", 8107 bdrv_get_device_or_node_name(parent_bs)); 8108 return; 8109 } 8110 8111 /* 8112 * Non-zoned block drivers do not follow zoned storage constraints 8113 * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned 8114 * drivers in a graph. 8115 */ 8116 if (!parent_bs->drv->supports_zoned_children && 8117 child_bs->bl.zoned == BLK_Z_HM) { 8118 /* 8119 * The host-aware model allows zoned storage constraints and random 8120 * write. Allow mixing host-aware and non-zoned drivers. Using 8121 * host-aware device as a regular device. 8122 */ 8123 error_setg(errp, "Cannot add a %s child to a %s parent", 8124 child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned", 8125 parent_bs->drv->supports_zoned_children ? 8126 "support zoned children" : "not support zoned children"); 8127 return; 8128 } 8129 8130 if (!QLIST_EMPTY(&child_bs->parents)) { 8131 error_setg(errp, "The node %s already has a parent", 8132 child_bs->node_name); 8133 return; 8134 } 8135 8136 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp); 8137 } 8138 8139 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) 8140 { 8141 BdrvChild *tmp; 8142 8143 GLOBAL_STATE_CODE(); 8144 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) { 8145 error_setg(errp, "The node %s does not support removing a child", 8146 bdrv_get_device_or_node_name(parent_bs)); 8147 return; 8148 } 8149 8150 QLIST_FOREACH(tmp, &parent_bs->children, next) { 8151 if (tmp == child) { 8152 break; 8153 } 8154 } 8155 8156 if (!tmp) { 8157 error_setg(errp, "The node %s does not have a child named %s", 8158 bdrv_get_device_or_node_name(parent_bs), 8159 bdrv_get_device_or_node_name(child->bs)); 8160 return; 8161 } 8162 8163 parent_bs->drv->bdrv_del_child(parent_bs, child, errp); 8164 } 8165 8166 int bdrv_make_empty(BdrvChild *c, Error **errp) 8167 { 8168 BlockDriver *drv = c->bs->drv; 8169 int ret; 8170 8171 GLOBAL_STATE_CODE(); 8172 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)); 8173 8174 if (!drv->bdrv_make_empty) { 8175 error_setg(errp, "%s does not support emptying nodes", 8176 drv->format_name); 8177 return -ENOTSUP; 8178 } 8179 8180 ret = drv->bdrv_make_empty(c->bs); 8181 if (ret < 0) { 8182 error_setg_errno(errp, -ret, "Failed to empty %s", 8183 c->bs->filename); 8184 return ret; 8185 } 8186 8187 return 0; 8188 } 8189 8190 /* 8191 * Return the child that @bs acts as an overlay for, and from which data may be 8192 * copied in COW or COR operations. Usually this is the backing file. 8193 */ 8194 BdrvChild *bdrv_cow_child(BlockDriverState *bs) 8195 { 8196 IO_CODE(); 8197 8198 if (!bs || !bs->drv) { 8199 return NULL; 8200 } 8201 8202 if (bs->drv->is_filter) { 8203 return NULL; 8204 } 8205 8206 if (!bs->backing) { 8207 return NULL; 8208 } 8209 8210 assert(bs->backing->role & BDRV_CHILD_COW); 8211 return bs->backing; 8212 } 8213 8214 /* 8215 * If @bs acts as a filter for exactly one of its children, return 8216 * that child. 8217 */ 8218 BdrvChild *bdrv_filter_child(BlockDriverState *bs) 8219 { 8220 BdrvChild *c; 8221 IO_CODE(); 8222 8223 if (!bs || !bs->drv) { 8224 return NULL; 8225 } 8226 8227 if (!bs->drv->is_filter) { 8228 return NULL; 8229 } 8230 8231 /* Only one of @backing or @file may be used */ 8232 assert(!(bs->backing && bs->file)); 8233 8234 c = bs->backing ?: bs->file; 8235 if (!c) { 8236 return NULL; 8237 } 8238 8239 assert(c->role & BDRV_CHILD_FILTERED); 8240 return c; 8241 } 8242 8243 /* 8244 * Return either the result of bdrv_cow_child() or bdrv_filter_child(), 8245 * whichever is non-NULL. 8246 * 8247 * Return NULL if both are NULL. 8248 */ 8249 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs) 8250 { 8251 BdrvChild *cow_child = bdrv_cow_child(bs); 8252 BdrvChild *filter_child = bdrv_filter_child(bs); 8253 IO_CODE(); 8254 8255 /* Filter nodes cannot have COW backing files */ 8256 assert(!(cow_child && filter_child)); 8257 8258 return cow_child ?: filter_child; 8259 } 8260 8261 /* 8262 * Return the primary child of this node: For filters, that is the 8263 * filtered child. For other nodes, that is usually the child storing 8264 * metadata. 8265 * (A generally more helpful description is that this is (usually) the 8266 * child that has the same filename as @bs.) 8267 * 8268 * Drivers do not necessarily have a primary child; for example quorum 8269 * does not. 8270 */ 8271 BdrvChild *bdrv_primary_child(BlockDriverState *bs) 8272 { 8273 BdrvChild *c, *found = NULL; 8274 IO_CODE(); 8275 8276 QLIST_FOREACH(c, &bs->children, next) { 8277 if (c->role & BDRV_CHILD_PRIMARY) { 8278 assert(!found); 8279 found = c; 8280 } 8281 } 8282 8283 return found; 8284 } 8285 8286 static BlockDriverState * GRAPH_RDLOCK 8287 bdrv_do_skip_filters(BlockDriverState *bs, bool stop_on_explicit_filter) 8288 { 8289 BdrvChild *c; 8290 8291 if (!bs) { 8292 return NULL; 8293 } 8294 8295 while (!(stop_on_explicit_filter && !bs->implicit)) { 8296 c = bdrv_filter_child(bs); 8297 if (!c) { 8298 /* 8299 * A filter that is embedded in a working block graph must 8300 * have a child. Assert this here so this function does 8301 * not return a filter node that is not expected by the 8302 * caller. 8303 */ 8304 assert(!bs->drv || !bs->drv->is_filter); 8305 break; 8306 } 8307 bs = c->bs; 8308 } 8309 /* 8310 * Note that this treats nodes with bs->drv == NULL as not being 8311 * filters (bs->drv == NULL should be replaced by something else 8312 * anyway). 8313 * The advantage of this behavior is that this function will thus 8314 * always return a non-NULL value (given a non-NULL @bs). 8315 */ 8316 8317 return bs; 8318 } 8319 8320 /* 8321 * Return the first BDS that has not been added implicitly or that 8322 * does not have a filtered child down the chain starting from @bs 8323 * (including @bs itself). 8324 */ 8325 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs) 8326 { 8327 GLOBAL_STATE_CODE(); 8328 return bdrv_do_skip_filters(bs, true); 8329 } 8330 8331 /* 8332 * Return the first BDS that does not have a filtered child down the 8333 * chain starting from @bs (including @bs itself). 8334 */ 8335 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs) 8336 { 8337 IO_CODE(); 8338 return bdrv_do_skip_filters(bs, false); 8339 } 8340 8341 /* 8342 * For a backing chain, return the first non-filter backing image of 8343 * the first non-filter image. 8344 */ 8345 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs) 8346 { 8347 IO_CODE(); 8348 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs))); 8349 } 8350 8351 /** 8352 * Check whether [offset, offset + bytes) overlaps with the cached 8353 * block-status data region. 8354 * 8355 * If so, and @pnum is not NULL, set *pnum to `bsc.data_end - offset`, 8356 * which is what bdrv_bsc_is_data()'s interface needs. 8357 * Otherwise, *pnum is not touched. 8358 */ 8359 static bool bdrv_bsc_range_overlaps_locked(BlockDriverState *bs, 8360 int64_t offset, int64_t bytes, 8361 int64_t *pnum) 8362 { 8363 BdrvBlockStatusCache *bsc = qatomic_rcu_read(&bs->block_status_cache); 8364 bool overlaps; 8365 8366 overlaps = 8367 qatomic_read(&bsc->valid) && 8368 ranges_overlap(offset, bytes, bsc->data_start, 8369 bsc->data_end - bsc->data_start); 8370 8371 if (overlaps && pnum) { 8372 *pnum = bsc->data_end - offset; 8373 } 8374 8375 return overlaps; 8376 } 8377 8378 /** 8379 * See block_int.h for this function's documentation. 8380 */ 8381 bool bdrv_bsc_is_data(BlockDriverState *bs, int64_t offset, int64_t *pnum) 8382 { 8383 IO_CODE(); 8384 RCU_READ_LOCK_GUARD(); 8385 return bdrv_bsc_range_overlaps_locked(bs, offset, 1, pnum); 8386 } 8387 8388 /** 8389 * See block_int.h for this function's documentation. 8390 */ 8391 void bdrv_bsc_invalidate_range(BlockDriverState *bs, 8392 int64_t offset, int64_t bytes) 8393 { 8394 IO_CODE(); 8395 RCU_READ_LOCK_GUARD(); 8396 8397 if (bdrv_bsc_range_overlaps_locked(bs, offset, bytes, NULL)) { 8398 qatomic_set(&bs->block_status_cache->valid, false); 8399 } 8400 } 8401 8402 /** 8403 * See block_int.h for this function's documentation. 8404 */ 8405 void bdrv_bsc_fill(BlockDriverState *bs, int64_t offset, int64_t bytes) 8406 { 8407 BdrvBlockStatusCache *new_bsc = g_new(BdrvBlockStatusCache, 1); 8408 BdrvBlockStatusCache *old_bsc; 8409 IO_CODE(); 8410 8411 *new_bsc = (BdrvBlockStatusCache) { 8412 .valid = true, 8413 .data_start = offset, 8414 .data_end = offset + bytes, 8415 }; 8416 8417 QEMU_LOCK_GUARD(&bs->bsc_modify_lock); 8418 8419 old_bsc = qatomic_rcu_read(&bs->block_status_cache); 8420 qatomic_rcu_set(&bs->block_status_cache, new_bsc); 8421 if (old_bsc) { 8422 g_free_rcu(old_bsc, rcu); 8423 } 8424 } 8425