1 /* 2 * QEMU System Emulator block driver 3 * 4 * Copyright (c) 2003 Fabrice Bellard 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 25 #include "qemu/osdep.h" 26 #include "block/trace.h" 27 #include "block/block_int.h" 28 #include "block/blockjob.h" 29 #include "block/nbd.h" 30 #include "block/qdict.h" 31 #include "qemu/error-report.h" 32 #include "module_block.h" 33 #include "qemu/main-loop.h" 34 #include "qemu/module.h" 35 #include "qapi/error.h" 36 #include "qapi/qmp/qdict.h" 37 #include "qapi/qmp/qjson.h" 38 #include "qapi/qmp/qnull.h" 39 #include "qapi/qmp/qstring.h" 40 #include "qapi/qobject-output-visitor.h" 41 #include "qapi/qapi-visit-block-core.h" 42 #include "sysemu/block-backend.h" 43 #include "sysemu/sysemu.h" 44 #include "qemu/notify.h" 45 #include "qemu/option.h" 46 #include "qemu/coroutine.h" 47 #include "block/qapi.h" 48 #include "qemu/timer.h" 49 #include "qemu/cutils.h" 50 #include "qemu/id.h" 51 52 #ifdef CONFIG_BSD 53 #include <sys/ioctl.h> 54 #include <sys/queue.h> 55 #ifndef __DragonFly__ 56 #include <sys/disk.h> 57 #endif 58 #endif 59 60 #ifdef _WIN32 61 #include <windows.h> 62 #endif 63 64 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */ 65 66 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states = 67 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states); 68 69 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states = 70 QTAILQ_HEAD_INITIALIZER(all_bdrv_states); 71 72 static QLIST_HEAD(, BlockDriver) bdrv_drivers = 73 QLIST_HEAD_INITIALIZER(bdrv_drivers); 74 75 static BlockDriverState *bdrv_open_inherit(const char *filename, 76 const char *reference, 77 QDict *options, int flags, 78 BlockDriverState *parent, 79 const BdrvChildClass *child_class, 80 BdrvChildRole child_role, 81 Error **errp); 82 83 /* If non-zero, use only whitelisted block drivers */ 84 static int use_bdrv_whitelist; 85 86 #ifdef _WIN32 87 static int is_windows_drive_prefix(const char *filename) 88 { 89 return (((filename[0] >= 'a' && filename[0] <= 'z') || 90 (filename[0] >= 'A' && filename[0] <= 'Z')) && 91 filename[1] == ':'); 92 } 93 94 int is_windows_drive(const char *filename) 95 { 96 if (is_windows_drive_prefix(filename) && 97 filename[2] == '\0') 98 return 1; 99 if (strstart(filename, "\\\\.\\", NULL) || 100 strstart(filename, "//./", NULL)) 101 return 1; 102 return 0; 103 } 104 #endif 105 106 size_t bdrv_opt_mem_align(BlockDriverState *bs) 107 { 108 if (!bs || !bs->drv) { 109 /* page size or 4k (hdd sector size) should be on the safe side */ 110 return MAX(4096, qemu_real_host_page_size); 111 } 112 113 return bs->bl.opt_mem_alignment; 114 } 115 116 size_t bdrv_min_mem_align(BlockDriverState *bs) 117 { 118 if (!bs || !bs->drv) { 119 /* page size or 4k (hdd sector size) should be on the safe side */ 120 return MAX(4096, qemu_real_host_page_size); 121 } 122 123 return bs->bl.min_mem_alignment; 124 } 125 126 /* check if the path starts with "<protocol>:" */ 127 int path_has_protocol(const char *path) 128 { 129 const char *p; 130 131 #ifdef _WIN32 132 if (is_windows_drive(path) || 133 is_windows_drive_prefix(path)) { 134 return 0; 135 } 136 p = path + strcspn(path, ":/\\"); 137 #else 138 p = path + strcspn(path, ":/"); 139 #endif 140 141 return *p == ':'; 142 } 143 144 int path_is_absolute(const char *path) 145 { 146 #ifdef _WIN32 147 /* specific case for names like: "\\.\d:" */ 148 if (is_windows_drive(path) || is_windows_drive_prefix(path)) { 149 return 1; 150 } 151 return (*path == '/' || *path == '\\'); 152 #else 153 return (*path == '/'); 154 #endif 155 } 156 157 /* if filename is absolute, just return its duplicate. Otherwise, build a 158 path to it by considering it is relative to base_path. URL are 159 supported. */ 160 char *path_combine(const char *base_path, const char *filename) 161 { 162 const char *protocol_stripped = NULL; 163 const char *p, *p1; 164 char *result; 165 int len; 166 167 if (path_is_absolute(filename)) { 168 return g_strdup(filename); 169 } 170 171 if (path_has_protocol(base_path)) { 172 protocol_stripped = strchr(base_path, ':'); 173 if (protocol_stripped) { 174 protocol_stripped++; 175 } 176 } 177 p = protocol_stripped ?: base_path; 178 179 p1 = strrchr(base_path, '/'); 180 #ifdef _WIN32 181 { 182 const char *p2; 183 p2 = strrchr(base_path, '\\'); 184 if (!p1 || p2 > p1) { 185 p1 = p2; 186 } 187 } 188 #endif 189 if (p1) { 190 p1++; 191 } else { 192 p1 = base_path; 193 } 194 if (p1 > p) { 195 p = p1; 196 } 197 len = p - base_path; 198 199 result = g_malloc(len + strlen(filename) + 1); 200 memcpy(result, base_path, len); 201 strcpy(result + len, filename); 202 203 return result; 204 } 205 206 /* 207 * Helper function for bdrv_parse_filename() implementations to remove optional 208 * protocol prefixes (especially "file:") from a filename and for putting the 209 * stripped filename into the options QDict if there is such a prefix. 210 */ 211 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, 212 QDict *options) 213 { 214 if (strstart(filename, prefix, &filename)) { 215 /* Stripping the explicit protocol prefix may result in a protocol 216 * prefix being (wrongly) detected (if the filename contains a colon) */ 217 if (path_has_protocol(filename)) { 218 QString *fat_filename; 219 220 /* This means there is some colon before the first slash; therefore, 221 * this cannot be an absolute path */ 222 assert(!path_is_absolute(filename)); 223 224 /* And we can thus fix the protocol detection issue by prefixing it 225 * by "./" */ 226 fat_filename = qstring_from_str("./"); 227 qstring_append(fat_filename, filename); 228 229 assert(!path_has_protocol(qstring_get_str(fat_filename))); 230 231 qdict_put(options, "filename", fat_filename); 232 } else { 233 /* If no protocol prefix was detected, we can use the shortened 234 * filename as-is */ 235 qdict_put_str(options, "filename", filename); 236 } 237 } 238 } 239 240 241 /* Returns whether the image file is opened as read-only. Note that this can 242 * return false and writing to the image file is still not possible because the 243 * image is inactivated. */ 244 bool bdrv_is_read_only(BlockDriverState *bs) 245 { 246 return bs->read_only; 247 } 248 249 int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, 250 bool ignore_allow_rdw, Error **errp) 251 { 252 /* Do not set read_only if copy_on_read is enabled */ 253 if (bs->copy_on_read && read_only) { 254 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled", 255 bdrv_get_device_or_node_name(bs)); 256 return -EINVAL; 257 } 258 259 /* Do not clear read_only if it is prohibited */ 260 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) && 261 !ignore_allow_rdw) 262 { 263 error_setg(errp, "Node '%s' is read only", 264 bdrv_get_device_or_node_name(bs)); 265 return -EPERM; 266 } 267 268 return 0; 269 } 270 271 /* 272 * Called by a driver that can only provide a read-only image. 273 * 274 * Returns 0 if the node is already read-only or it could switch the node to 275 * read-only because BDRV_O_AUTO_RDONLY is set. 276 * 277 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set 278 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg 279 * is not NULL, it is used as the error message for the Error object. 280 */ 281 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg, 282 Error **errp) 283 { 284 int ret = 0; 285 286 if (!(bs->open_flags & BDRV_O_RDWR)) { 287 return 0; 288 } 289 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) { 290 goto fail; 291 } 292 293 ret = bdrv_can_set_read_only(bs, true, false, NULL); 294 if (ret < 0) { 295 goto fail; 296 } 297 298 bs->read_only = true; 299 bs->open_flags &= ~BDRV_O_RDWR; 300 301 return 0; 302 303 fail: 304 error_setg(errp, "%s", errmsg ?: "Image is read-only"); 305 return -EACCES; 306 } 307 308 /* 309 * If @backing is empty, this function returns NULL without setting 310 * @errp. In all other cases, NULL will only be returned with @errp 311 * set. 312 * 313 * Therefore, a return value of NULL without @errp set means that 314 * there is no backing file; if @errp is set, there is one but its 315 * absolute filename cannot be generated. 316 */ 317 char *bdrv_get_full_backing_filename_from_filename(const char *backed, 318 const char *backing, 319 Error **errp) 320 { 321 if (backing[0] == '\0') { 322 return NULL; 323 } else if (path_has_protocol(backing) || path_is_absolute(backing)) { 324 return g_strdup(backing); 325 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) { 326 error_setg(errp, "Cannot use relative backing file names for '%s'", 327 backed); 328 return NULL; 329 } else { 330 return path_combine(backed, backing); 331 } 332 } 333 334 /* 335 * If @filename is empty or NULL, this function returns NULL without 336 * setting @errp. In all other cases, NULL will only be returned with 337 * @errp set. 338 */ 339 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to, 340 const char *filename, Error **errp) 341 { 342 char *dir, *full_name; 343 344 if (!filename || filename[0] == '\0') { 345 return NULL; 346 } else if (path_has_protocol(filename) || path_is_absolute(filename)) { 347 return g_strdup(filename); 348 } 349 350 dir = bdrv_dirname(relative_to, errp); 351 if (!dir) { 352 return NULL; 353 } 354 355 full_name = g_strconcat(dir, filename, NULL); 356 g_free(dir); 357 return full_name; 358 } 359 360 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp) 361 { 362 return bdrv_make_absolute_filename(bs, bs->backing_file, errp); 363 } 364 365 void bdrv_register(BlockDriver *bdrv) 366 { 367 assert(bdrv->format_name); 368 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list); 369 } 370 371 BlockDriverState *bdrv_new(void) 372 { 373 BlockDriverState *bs; 374 int i; 375 376 bs = g_new0(BlockDriverState, 1); 377 QLIST_INIT(&bs->dirty_bitmaps); 378 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 379 QLIST_INIT(&bs->op_blockers[i]); 380 } 381 notifier_with_return_list_init(&bs->before_write_notifiers); 382 qemu_co_mutex_init(&bs->reqs_lock); 383 qemu_mutex_init(&bs->dirty_bitmap_mutex); 384 bs->refcnt = 1; 385 bs->aio_context = qemu_get_aio_context(); 386 387 qemu_co_queue_init(&bs->flush_queue); 388 389 for (i = 0; i < bdrv_drain_all_count; i++) { 390 bdrv_drained_begin(bs); 391 } 392 393 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list); 394 395 return bs; 396 } 397 398 static BlockDriver *bdrv_do_find_format(const char *format_name) 399 { 400 BlockDriver *drv1; 401 402 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 403 if (!strcmp(drv1->format_name, format_name)) { 404 return drv1; 405 } 406 } 407 408 return NULL; 409 } 410 411 BlockDriver *bdrv_find_format(const char *format_name) 412 { 413 BlockDriver *drv1; 414 int i; 415 416 drv1 = bdrv_do_find_format(format_name); 417 if (drv1) { 418 return drv1; 419 } 420 421 /* The driver isn't registered, maybe we need to load a module */ 422 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 423 if (!strcmp(block_driver_modules[i].format_name, format_name)) { 424 block_module_load_one(block_driver_modules[i].library_name); 425 break; 426 } 427 } 428 429 return bdrv_do_find_format(format_name); 430 } 431 432 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only) 433 { 434 static const char *whitelist_rw[] = { 435 CONFIG_BDRV_RW_WHITELIST 436 }; 437 static const char *whitelist_ro[] = { 438 CONFIG_BDRV_RO_WHITELIST 439 }; 440 const char **p; 441 442 if (!whitelist_rw[0] && !whitelist_ro[0]) { 443 return 1; /* no whitelist, anything goes */ 444 } 445 446 for (p = whitelist_rw; *p; p++) { 447 if (!strcmp(format_name, *p)) { 448 return 1; 449 } 450 } 451 if (read_only) { 452 for (p = whitelist_ro; *p; p++) { 453 if (!strcmp(format_name, *p)) { 454 return 1; 455 } 456 } 457 } 458 return 0; 459 } 460 461 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only) 462 { 463 return bdrv_format_is_whitelisted(drv->format_name, read_only); 464 } 465 466 bool bdrv_uses_whitelist(void) 467 { 468 return use_bdrv_whitelist; 469 } 470 471 typedef struct CreateCo { 472 BlockDriver *drv; 473 char *filename; 474 QemuOpts *opts; 475 int ret; 476 Error *err; 477 } CreateCo; 478 479 static void coroutine_fn bdrv_create_co_entry(void *opaque) 480 { 481 Error *local_err = NULL; 482 int ret; 483 484 CreateCo *cco = opaque; 485 assert(cco->drv); 486 487 ret = cco->drv->bdrv_co_create_opts(cco->drv, 488 cco->filename, cco->opts, &local_err); 489 error_propagate(&cco->err, local_err); 490 cco->ret = ret; 491 } 492 493 int bdrv_create(BlockDriver *drv, const char* filename, 494 QemuOpts *opts, Error **errp) 495 { 496 int ret; 497 498 Coroutine *co; 499 CreateCo cco = { 500 .drv = drv, 501 .filename = g_strdup(filename), 502 .opts = opts, 503 .ret = NOT_DONE, 504 .err = NULL, 505 }; 506 507 if (!drv->bdrv_co_create_opts) { 508 error_setg(errp, "Driver '%s' does not support image creation", drv->format_name); 509 ret = -ENOTSUP; 510 goto out; 511 } 512 513 if (qemu_in_coroutine()) { 514 /* Fast-path if already in coroutine context */ 515 bdrv_create_co_entry(&cco); 516 } else { 517 co = qemu_coroutine_create(bdrv_create_co_entry, &cco); 518 qemu_coroutine_enter(co); 519 while (cco.ret == NOT_DONE) { 520 aio_poll(qemu_get_aio_context(), true); 521 } 522 } 523 524 ret = cco.ret; 525 if (ret < 0) { 526 if (cco.err) { 527 error_propagate(errp, cco.err); 528 } else { 529 error_setg_errno(errp, -ret, "Could not create image"); 530 } 531 } 532 533 out: 534 g_free(cco.filename); 535 return ret; 536 } 537 538 /** 539 * Helper function for bdrv_create_file_fallback(): Resize @blk to at 540 * least the given @minimum_size. 541 * 542 * On success, return @blk's actual length. 543 * Otherwise, return -errno. 544 */ 545 static int64_t create_file_fallback_truncate(BlockBackend *blk, 546 int64_t minimum_size, Error **errp) 547 { 548 Error *local_err = NULL; 549 int64_t size; 550 int ret; 551 552 ret = blk_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0, 553 &local_err); 554 if (ret < 0 && ret != -ENOTSUP) { 555 error_propagate(errp, local_err); 556 return ret; 557 } 558 559 size = blk_getlength(blk); 560 if (size < 0) { 561 error_free(local_err); 562 error_setg_errno(errp, -size, 563 "Failed to inquire the new image file's length"); 564 return size; 565 } 566 567 if (size < minimum_size) { 568 /* Need to grow the image, but we failed to do that */ 569 error_propagate(errp, local_err); 570 return -ENOTSUP; 571 } 572 573 error_free(local_err); 574 local_err = NULL; 575 576 return size; 577 } 578 579 /** 580 * Helper function for bdrv_create_file_fallback(): Zero the first 581 * sector to remove any potentially pre-existing image header. 582 */ 583 static int create_file_fallback_zero_first_sector(BlockBackend *blk, 584 int64_t current_size, 585 Error **errp) 586 { 587 int64_t bytes_to_clear; 588 int ret; 589 590 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE); 591 if (bytes_to_clear) { 592 ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP); 593 if (ret < 0) { 594 error_setg_errno(errp, -ret, 595 "Failed to clear the new image's first sector"); 596 return ret; 597 } 598 } 599 600 return 0; 601 } 602 603 /** 604 * Simple implementation of bdrv_co_create_opts for protocol drivers 605 * which only support creation via opening a file 606 * (usually existing raw storage device) 607 */ 608 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv, 609 const char *filename, 610 QemuOpts *opts, 611 Error **errp) 612 { 613 BlockBackend *blk; 614 QDict *options; 615 int64_t size = 0; 616 char *buf = NULL; 617 PreallocMode prealloc; 618 Error *local_err = NULL; 619 int ret; 620 621 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0); 622 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC); 623 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf, 624 PREALLOC_MODE_OFF, &local_err); 625 g_free(buf); 626 if (local_err) { 627 error_propagate(errp, local_err); 628 return -EINVAL; 629 } 630 631 if (prealloc != PREALLOC_MODE_OFF) { 632 error_setg(errp, "Unsupported preallocation mode '%s'", 633 PreallocMode_str(prealloc)); 634 return -ENOTSUP; 635 } 636 637 options = qdict_new(); 638 qdict_put_str(options, "driver", drv->format_name); 639 640 blk = blk_new_open(filename, NULL, options, 641 BDRV_O_RDWR | BDRV_O_RESIZE, errp); 642 if (!blk) { 643 error_prepend(errp, "Protocol driver '%s' does not support image " 644 "creation, and opening the image failed: ", 645 drv->format_name); 646 return -EINVAL; 647 } 648 649 size = create_file_fallback_truncate(blk, size, errp); 650 if (size < 0) { 651 ret = size; 652 goto out; 653 } 654 655 ret = create_file_fallback_zero_first_sector(blk, size, errp); 656 if (ret < 0) { 657 goto out; 658 } 659 660 ret = 0; 661 out: 662 blk_unref(blk); 663 return ret; 664 } 665 666 int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp) 667 { 668 BlockDriver *drv; 669 670 drv = bdrv_find_protocol(filename, true, errp); 671 if (drv == NULL) { 672 return -ENOENT; 673 } 674 675 return bdrv_create(drv, filename, opts, errp); 676 } 677 678 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp) 679 { 680 Error *local_err = NULL; 681 int ret; 682 683 assert(bs != NULL); 684 685 if (!bs->drv) { 686 error_setg(errp, "Block node '%s' is not opened", bs->filename); 687 return -ENOMEDIUM; 688 } 689 690 if (!bs->drv->bdrv_co_delete_file) { 691 error_setg(errp, "Driver '%s' does not support image deletion", 692 bs->drv->format_name); 693 return -ENOTSUP; 694 } 695 696 ret = bs->drv->bdrv_co_delete_file(bs, &local_err); 697 if (ret < 0) { 698 error_propagate(errp, local_err); 699 } 700 701 return ret; 702 } 703 704 /** 705 * Try to get @bs's logical and physical block size. 706 * On success, store them in @bsz struct and return 0. 707 * On failure return -errno. 708 * @bs must not be empty. 709 */ 710 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz) 711 { 712 BlockDriver *drv = bs->drv; 713 714 if (drv && drv->bdrv_probe_blocksizes) { 715 return drv->bdrv_probe_blocksizes(bs, bsz); 716 } else if (drv && drv->is_filter && bs->file) { 717 return bdrv_probe_blocksizes(bs->file->bs, bsz); 718 } 719 720 return -ENOTSUP; 721 } 722 723 /** 724 * Try to get @bs's geometry (cyls, heads, sectors). 725 * On success, store them in @geo struct and return 0. 726 * On failure return -errno. 727 * @bs must not be empty. 728 */ 729 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo) 730 { 731 BlockDriver *drv = bs->drv; 732 733 if (drv && drv->bdrv_probe_geometry) { 734 return drv->bdrv_probe_geometry(bs, geo); 735 } else if (drv && drv->is_filter && bs->file) { 736 return bdrv_probe_geometry(bs->file->bs, geo); 737 } 738 739 return -ENOTSUP; 740 } 741 742 /* 743 * Create a uniquely-named empty temporary file. 744 * Return 0 upon success, otherwise a negative errno value. 745 */ 746 int get_tmp_filename(char *filename, int size) 747 { 748 #ifdef _WIN32 749 char temp_dir[MAX_PATH]; 750 /* GetTempFileName requires that its output buffer (4th param) 751 have length MAX_PATH or greater. */ 752 assert(size >= MAX_PATH); 753 return (GetTempPath(MAX_PATH, temp_dir) 754 && GetTempFileName(temp_dir, "qem", 0, filename) 755 ? 0 : -GetLastError()); 756 #else 757 int fd; 758 const char *tmpdir; 759 tmpdir = getenv("TMPDIR"); 760 if (!tmpdir) { 761 tmpdir = "/var/tmp"; 762 } 763 if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) { 764 return -EOVERFLOW; 765 } 766 fd = mkstemp(filename); 767 if (fd < 0) { 768 return -errno; 769 } 770 if (close(fd) != 0) { 771 unlink(filename); 772 return -errno; 773 } 774 return 0; 775 #endif 776 } 777 778 /* 779 * Detect host devices. By convention, /dev/cdrom[N] is always 780 * recognized as a host CDROM. 781 */ 782 static BlockDriver *find_hdev_driver(const char *filename) 783 { 784 int score_max = 0, score; 785 BlockDriver *drv = NULL, *d; 786 787 QLIST_FOREACH(d, &bdrv_drivers, list) { 788 if (d->bdrv_probe_device) { 789 score = d->bdrv_probe_device(filename); 790 if (score > score_max) { 791 score_max = score; 792 drv = d; 793 } 794 } 795 } 796 797 return drv; 798 } 799 800 static BlockDriver *bdrv_do_find_protocol(const char *protocol) 801 { 802 BlockDriver *drv1; 803 804 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 805 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) { 806 return drv1; 807 } 808 } 809 810 return NULL; 811 } 812 813 BlockDriver *bdrv_find_protocol(const char *filename, 814 bool allow_protocol_prefix, 815 Error **errp) 816 { 817 BlockDriver *drv1; 818 char protocol[128]; 819 int len; 820 const char *p; 821 int i; 822 823 /* TODO Drivers without bdrv_file_open must be specified explicitly */ 824 825 /* 826 * XXX(hch): we really should not let host device detection 827 * override an explicit protocol specification, but moving this 828 * later breaks access to device names with colons in them. 829 * Thanks to the brain-dead persistent naming schemes on udev- 830 * based Linux systems those actually are quite common. 831 */ 832 drv1 = find_hdev_driver(filename); 833 if (drv1) { 834 return drv1; 835 } 836 837 if (!path_has_protocol(filename) || !allow_protocol_prefix) { 838 return &bdrv_file; 839 } 840 841 p = strchr(filename, ':'); 842 assert(p != NULL); 843 len = p - filename; 844 if (len > sizeof(protocol) - 1) 845 len = sizeof(protocol) - 1; 846 memcpy(protocol, filename, len); 847 protocol[len] = '\0'; 848 849 drv1 = bdrv_do_find_protocol(protocol); 850 if (drv1) { 851 return drv1; 852 } 853 854 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 855 if (block_driver_modules[i].protocol_name && 856 !strcmp(block_driver_modules[i].protocol_name, protocol)) { 857 block_module_load_one(block_driver_modules[i].library_name); 858 break; 859 } 860 } 861 862 drv1 = bdrv_do_find_protocol(protocol); 863 if (!drv1) { 864 error_setg(errp, "Unknown protocol '%s'", protocol); 865 } 866 return drv1; 867 } 868 869 /* 870 * Guess image format by probing its contents. 871 * This is not a good idea when your image is raw (CVE-2008-2004), but 872 * we do it anyway for backward compatibility. 873 * 874 * @buf contains the image's first @buf_size bytes. 875 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE, 876 * but can be smaller if the image file is smaller) 877 * @filename is its filename. 878 * 879 * For all block drivers, call the bdrv_probe() method to get its 880 * probing score. 881 * Return the first block driver with the highest probing score. 882 */ 883 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size, 884 const char *filename) 885 { 886 int score_max = 0, score; 887 BlockDriver *drv = NULL, *d; 888 889 QLIST_FOREACH(d, &bdrv_drivers, list) { 890 if (d->bdrv_probe) { 891 score = d->bdrv_probe(buf, buf_size, filename); 892 if (score > score_max) { 893 score_max = score; 894 drv = d; 895 } 896 } 897 } 898 899 return drv; 900 } 901 902 static int find_image_format(BlockBackend *file, const char *filename, 903 BlockDriver **pdrv, Error **errp) 904 { 905 BlockDriver *drv; 906 uint8_t buf[BLOCK_PROBE_BUF_SIZE]; 907 int ret = 0; 908 909 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */ 910 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) { 911 *pdrv = &bdrv_raw; 912 return ret; 913 } 914 915 ret = blk_pread(file, 0, buf, sizeof(buf)); 916 if (ret < 0) { 917 error_setg_errno(errp, -ret, "Could not read image for determining its " 918 "format"); 919 *pdrv = NULL; 920 return ret; 921 } 922 923 drv = bdrv_probe_all(buf, ret, filename); 924 if (!drv) { 925 error_setg(errp, "Could not determine image format: No compatible " 926 "driver found"); 927 ret = -ENOENT; 928 } 929 *pdrv = drv; 930 return ret; 931 } 932 933 /** 934 * Set the current 'total_sectors' value 935 * Return 0 on success, -errno on error. 936 */ 937 int refresh_total_sectors(BlockDriverState *bs, int64_t hint) 938 { 939 BlockDriver *drv = bs->drv; 940 941 if (!drv) { 942 return -ENOMEDIUM; 943 } 944 945 /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */ 946 if (bdrv_is_sg(bs)) 947 return 0; 948 949 /* query actual device if possible, otherwise just trust the hint */ 950 if (drv->bdrv_getlength) { 951 int64_t length = drv->bdrv_getlength(bs); 952 if (length < 0) { 953 return length; 954 } 955 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE); 956 } 957 958 bs->total_sectors = hint; 959 return 0; 960 } 961 962 /** 963 * Combines a QDict of new block driver @options with any missing options taken 964 * from @old_options, so that leaving out an option defaults to its old value. 965 */ 966 static void bdrv_join_options(BlockDriverState *bs, QDict *options, 967 QDict *old_options) 968 { 969 if (bs->drv && bs->drv->bdrv_join_options) { 970 bs->drv->bdrv_join_options(options, old_options); 971 } else { 972 qdict_join(options, old_options, false); 973 } 974 } 975 976 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts, 977 int open_flags, 978 Error **errp) 979 { 980 Error *local_err = NULL; 981 char *value = qemu_opt_get_del(opts, "detect-zeroes"); 982 BlockdevDetectZeroesOptions detect_zeroes = 983 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value, 984 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err); 985 g_free(value); 986 if (local_err) { 987 error_propagate(errp, local_err); 988 return detect_zeroes; 989 } 990 991 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP && 992 !(open_flags & BDRV_O_UNMAP)) 993 { 994 error_setg(errp, "setting detect-zeroes to unmap is not allowed " 995 "without setting discard operation to unmap"); 996 } 997 998 return detect_zeroes; 999 } 1000 1001 /** 1002 * Set open flags for aio engine 1003 * 1004 * Return 0 on success, -1 if the engine specified is invalid 1005 */ 1006 int bdrv_parse_aio(const char *mode, int *flags) 1007 { 1008 if (!strcmp(mode, "threads")) { 1009 /* do nothing, default */ 1010 } else if (!strcmp(mode, "native")) { 1011 *flags |= BDRV_O_NATIVE_AIO; 1012 #ifdef CONFIG_LINUX_IO_URING 1013 } else if (!strcmp(mode, "io_uring")) { 1014 *flags |= BDRV_O_IO_URING; 1015 #endif 1016 } else { 1017 return -1; 1018 } 1019 1020 return 0; 1021 } 1022 1023 /** 1024 * Set open flags for a given discard mode 1025 * 1026 * Return 0 on success, -1 if the discard mode was invalid. 1027 */ 1028 int bdrv_parse_discard_flags(const char *mode, int *flags) 1029 { 1030 *flags &= ~BDRV_O_UNMAP; 1031 1032 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) { 1033 /* do nothing */ 1034 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) { 1035 *flags |= BDRV_O_UNMAP; 1036 } else { 1037 return -1; 1038 } 1039 1040 return 0; 1041 } 1042 1043 /** 1044 * Set open flags for a given cache mode 1045 * 1046 * Return 0 on success, -1 if the cache mode was invalid. 1047 */ 1048 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough) 1049 { 1050 *flags &= ~BDRV_O_CACHE_MASK; 1051 1052 if (!strcmp(mode, "off") || !strcmp(mode, "none")) { 1053 *writethrough = false; 1054 *flags |= BDRV_O_NOCACHE; 1055 } else if (!strcmp(mode, "directsync")) { 1056 *writethrough = true; 1057 *flags |= BDRV_O_NOCACHE; 1058 } else if (!strcmp(mode, "writeback")) { 1059 *writethrough = false; 1060 } else if (!strcmp(mode, "unsafe")) { 1061 *writethrough = false; 1062 *flags |= BDRV_O_NO_FLUSH; 1063 } else if (!strcmp(mode, "writethrough")) { 1064 *writethrough = true; 1065 } else { 1066 return -1; 1067 } 1068 1069 return 0; 1070 } 1071 1072 static char *bdrv_child_get_parent_desc(BdrvChild *c) 1073 { 1074 BlockDriverState *parent = c->opaque; 1075 return g_strdup(bdrv_get_device_or_node_name(parent)); 1076 } 1077 1078 static void bdrv_child_cb_drained_begin(BdrvChild *child) 1079 { 1080 BlockDriverState *bs = child->opaque; 1081 bdrv_do_drained_begin_quiesce(bs, NULL, false); 1082 } 1083 1084 static bool bdrv_child_cb_drained_poll(BdrvChild *child) 1085 { 1086 BlockDriverState *bs = child->opaque; 1087 return bdrv_drain_poll(bs, false, NULL, false); 1088 } 1089 1090 static void bdrv_child_cb_drained_end(BdrvChild *child, 1091 int *drained_end_counter) 1092 { 1093 BlockDriverState *bs = child->opaque; 1094 bdrv_drained_end_no_poll(bs, drained_end_counter); 1095 } 1096 1097 static int bdrv_child_cb_inactivate(BdrvChild *child) 1098 { 1099 BlockDriverState *bs = child->opaque; 1100 assert(bs->open_flags & BDRV_O_INACTIVE); 1101 return 0; 1102 } 1103 1104 static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx, 1105 GSList **ignore, Error **errp) 1106 { 1107 BlockDriverState *bs = child->opaque; 1108 return bdrv_can_set_aio_context(bs, ctx, ignore, errp); 1109 } 1110 1111 static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx, 1112 GSList **ignore) 1113 { 1114 BlockDriverState *bs = child->opaque; 1115 return bdrv_set_aio_context_ignore(bs, ctx, ignore); 1116 } 1117 1118 /* 1119 * Returns the options and flags that a temporary snapshot should get, based on 1120 * the originally requested flags (the originally requested image will have 1121 * flags like a backing file) 1122 */ 1123 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options, 1124 int parent_flags, QDict *parent_options) 1125 { 1126 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY; 1127 1128 /* For temporary files, unconditional cache=unsafe is fine */ 1129 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off"); 1130 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on"); 1131 1132 /* Copy the read-only and discard options from the parent */ 1133 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1134 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD); 1135 1136 /* aio=native doesn't work for cache.direct=off, so disable it for the 1137 * temporary snapshot */ 1138 *child_flags &= ~BDRV_O_NATIVE_AIO; 1139 } 1140 1141 static void bdrv_backing_attach(BdrvChild *c) 1142 { 1143 BlockDriverState *parent = c->opaque; 1144 BlockDriverState *backing_hd = c->bs; 1145 1146 assert(!parent->backing_blocker); 1147 error_setg(&parent->backing_blocker, 1148 "node is used as backing hd of '%s'", 1149 bdrv_get_device_or_node_name(parent)); 1150 1151 bdrv_refresh_filename(backing_hd); 1152 1153 parent->open_flags &= ~BDRV_O_NO_BACKING; 1154 pstrcpy(parent->backing_file, sizeof(parent->backing_file), 1155 backing_hd->filename); 1156 pstrcpy(parent->backing_format, sizeof(parent->backing_format), 1157 backing_hd->drv ? backing_hd->drv->format_name : ""); 1158 1159 bdrv_op_block_all(backing_hd, parent->backing_blocker); 1160 /* Otherwise we won't be able to commit or stream */ 1161 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET, 1162 parent->backing_blocker); 1163 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM, 1164 parent->backing_blocker); 1165 /* 1166 * We do backup in 3 ways: 1167 * 1. drive backup 1168 * The target bs is new opened, and the source is top BDS 1169 * 2. blockdev backup 1170 * Both the source and the target are top BDSes. 1171 * 3. internal backup(used for block replication) 1172 * Both the source and the target are backing file 1173 * 1174 * In case 1 and 2, neither the source nor the target is the backing file. 1175 * In case 3, we will block the top BDS, so there is only one block job 1176 * for the top BDS and its backing chain. 1177 */ 1178 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE, 1179 parent->backing_blocker); 1180 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET, 1181 parent->backing_blocker); 1182 } 1183 1184 static void bdrv_backing_detach(BdrvChild *c) 1185 { 1186 BlockDriverState *parent = c->opaque; 1187 1188 assert(parent->backing_blocker); 1189 bdrv_op_unblock_all(c->bs, parent->backing_blocker); 1190 error_free(parent->backing_blocker); 1191 parent->backing_blocker = NULL; 1192 } 1193 1194 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base, 1195 const char *filename, Error **errp) 1196 { 1197 BlockDriverState *parent = c->opaque; 1198 bool read_only = bdrv_is_read_only(parent); 1199 int ret; 1200 1201 if (read_only) { 1202 ret = bdrv_reopen_set_read_only(parent, false, errp); 1203 if (ret < 0) { 1204 return ret; 1205 } 1206 } 1207 1208 ret = bdrv_change_backing_file(parent, filename, 1209 base->drv ? base->drv->format_name : ""); 1210 if (ret < 0) { 1211 error_setg_errno(errp, -ret, "Could not update backing file link"); 1212 } 1213 1214 if (read_only) { 1215 bdrv_reopen_set_read_only(parent, true, NULL); 1216 } 1217 1218 return ret; 1219 } 1220 1221 /* 1222 * Returns the options and flags that a generic child of a BDS should 1223 * get, based on the given options and flags for the parent BDS. 1224 */ 1225 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format, 1226 int *child_flags, QDict *child_options, 1227 int parent_flags, QDict *parent_options) 1228 { 1229 int flags = parent_flags; 1230 1231 /* 1232 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL. 1233 * Generally, the question to answer is: Should this child be 1234 * format-probed by default? 1235 */ 1236 1237 /* 1238 * Pure and non-filtered data children of non-format nodes should 1239 * be probed by default (even when the node itself has BDRV_O_PROTOCOL 1240 * set). This only affects a very limited set of drivers (namely 1241 * quorum and blkverify when this comment was written). 1242 * Force-clear BDRV_O_PROTOCOL then. 1243 */ 1244 if (!parent_is_format && 1245 (role & BDRV_CHILD_DATA) && 1246 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED))) 1247 { 1248 flags &= ~BDRV_O_PROTOCOL; 1249 } 1250 1251 /* 1252 * All children of format nodes (except for COW children) and all 1253 * metadata children in general should never be format-probed. 1254 * Force-set BDRV_O_PROTOCOL then. 1255 */ 1256 if ((parent_is_format && !(role & BDRV_CHILD_COW)) || 1257 (role & BDRV_CHILD_METADATA)) 1258 { 1259 flags |= BDRV_O_PROTOCOL; 1260 } 1261 1262 /* 1263 * If the cache mode isn't explicitly set, inherit direct and no-flush from 1264 * the parent. 1265 */ 1266 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT); 1267 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH); 1268 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE); 1269 1270 if (role & BDRV_CHILD_COW) { 1271 /* backing files are opened read-only by default */ 1272 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on"); 1273 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off"); 1274 } else { 1275 /* Inherit the read-only option from the parent if it's not set */ 1276 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1277 qdict_copy_default(child_options, parent_options, 1278 BDRV_OPT_AUTO_READ_ONLY); 1279 } 1280 1281 /* 1282 * bdrv_co_pdiscard() respects unmap policy for the parent, so we 1283 * can default to enable it on lower layers regardless of the 1284 * parent option. 1285 */ 1286 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap"); 1287 1288 /* Clear flags that only apply to the top layer */ 1289 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ); 1290 1291 if (role & BDRV_CHILD_METADATA) { 1292 flags &= ~BDRV_O_NO_IO; 1293 } 1294 if (role & BDRV_CHILD_COW) { 1295 flags &= ~BDRV_O_TEMPORARY; 1296 } 1297 1298 *child_flags = flags; 1299 } 1300 1301 static void bdrv_child_cb_attach(BdrvChild *child) 1302 { 1303 BlockDriverState *bs = child->opaque; 1304 1305 if (child->role & BDRV_CHILD_COW) { 1306 bdrv_backing_attach(child); 1307 } 1308 1309 bdrv_apply_subtree_drain(child, bs); 1310 } 1311 1312 static void bdrv_child_cb_detach(BdrvChild *child) 1313 { 1314 BlockDriverState *bs = child->opaque; 1315 1316 if (child->role & BDRV_CHILD_COW) { 1317 bdrv_backing_detach(child); 1318 } 1319 1320 bdrv_unapply_subtree_drain(child, bs); 1321 } 1322 1323 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base, 1324 const char *filename, Error **errp) 1325 { 1326 if (c->role & BDRV_CHILD_COW) { 1327 return bdrv_backing_update_filename(c, base, filename, errp); 1328 } 1329 return 0; 1330 } 1331 1332 const BdrvChildClass child_of_bds = { 1333 .parent_is_bds = true, 1334 .get_parent_desc = bdrv_child_get_parent_desc, 1335 .inherit_options = bdrv_inherited_options, 1336 .drained_begin = bdrv_child_cb_drained_begin, 1337 .drained_poll = bdrv_child_cb_drained_poll, 1338 .drained_end = bdrv_child_cb_drained_end, 1339 .attach = bdrv_child_cb_attach, 1340 .detach = bdrv_child_cb_detach, 1341 .inactivate = bdrv_child_cb_inactivate, 1342 .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx, 1343 .set_aio_ctx = bdrv_child_cb_set_aio_ctx, 1344 .update_filename = bdrv_child_cb_update_filename, 1345 }; 1346 1347 static int bdrv_open_flags(BlockDriverState *bs, int flags) 1348 { 1349 int open_flags = flags; 1350 1351 /* 1352 * Clear flags that are internal to the block layer before opening the 1353 * image. 1354 */ 1355 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL); 1356 1357 return open_flags; 1358 } 1359 1360 static void update_flags_from_options(int *flags, QemuOpts *opts) 1361 { 1362 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY); 1363 1364 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) { 1365 *flags |= BDRV_O_NO_FLUSH; 1366 } 1367 1368 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) { 1369 *flags |= BDRV_O_NOCACHE; 1370 } 1371 1372 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) { 1373 *flags |= BDRV_O_RDWR; 1374 } 1375 1376 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) { 1377 *flags |= BDRV_O_AUTO_RDONLY; 1378 } 1379 } 1380 1381 static void update_options_from_flags(QDict *options, int flags) 1382 { 1383 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) { 1384 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE); 1385 } 1386 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) { 1387 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH, 1388 flags & BDRV_O_NO_FLUSH); 1389 } 1390 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) { 1391 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR)); 1392 } 1393 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) { 1394 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY, 1395 flags & BDRV_O_AUTO_RDONLY); 1396 } 1397 } 1398 1399 static void bdrv_assign_node_name(BlockDriverState *bs, 1400 const char *node_name, 1401 Error **errp) 1402 { 1403 char *gen_node_name = NULL; 1404 1405 if (!node_name) { 1406 node_name = gen_node_name = id_generate(ID_BLOCK); 1407 } else if (!id_wellformed(node_name)) { 1408 /* 1409 * Check for empty string or invalid characters, but not if it is 1410 * generated (generated names use characters not available to the user) 1411 */ 1412 error_setg(errp, "Invalid node name"); 1413 return; 1414 } 1415 1416 /* takes care of avoiding namespaces collisions */ 1417 if (blk_by_name(node_name)) { 1418 error_setg(errp, "node-name=%s is conflicting with a device id", 1419 node_name); 1420 goto out; 1421 } 1422 1423 /* takes care of avoiding duplicates node names */ 1424 if (bdrv_find_node(node_name)) { 1425 error_setg(errp, "Duplicate node name"); 1426 goto out; 1427 } 1428 1429 /* Make sure that the node name isn't truncated */ 1430 if (strlen(node_name) >= sizeof(bs->node_name)) { 1431 error_setg(errp, "Node name too long"); 1432 goto out; 1433 } 1434 1435 /* copy node name into the bs and insert it into the graph list */ 1436 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name); 1437 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list); 1438 out: 1439 g_free(gen_node_name); 1440 } 1441 1442 static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, 1443 const char *node_name, QDict *options, 1444 int open_flags, Error **errp) 1445 { 1446 Error *local_err = NULL; 1447 int i, ret; 1448 1449 bdrv_assign_node_name(bs, node_name, &local_err); 1450 if (local_err) { 1451 error_propagate(errp, local_err); 1452 return -EINVAL; 1453 } 1454 1455 bs->drv = drv; 1456 bs->read_only = !(bs->open_flags & BDRV_O_RDWR); 1457 bs->opaque = g_malloc0(drv->instance_size); 1458 1459 if (drv->bdrv_file_open) { 1460 assert(!drv->bdrv_needs_filename || bs->filename[0]); 1461 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err); 1462 } else if (drv->bdrv_open) { 1463 ret = drv->bdrv_open(bs, options, open_flags, &local_err); 1464 } else { 1465 ret = 0; 1466 } 1467 1468 if (ret < 0) { 1469 if (local_err) { 1470 error_propagate(errp, local_err); 1471 } else if (bs->filename[0]) { 1472 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename); 1473 } else { 1474 error_setg_errno(errp, -ret, "Could not open image"); 1475 } 1476 goto open_failed; 1477 } 1478 1479 ret = refresh_total_sectors(bs, bs->total_sectors); 1480 if (ret < 0) { 1481 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 1482 return ret; 1483 } 1484 1485 bdrv_refresh_limits(bs, &local_err); 1486 if (local_err) { 1487 error_propagate(errp, local_err); 1488 return -EINVAL; 1489 } 1490 1491 assert(bdrv_opt_mem_align(bs) != 0); 1492 assert(bdrv_min_mem_align(bs) != 0); 1493 assert(is_power_of_2(bs->bl.request_alignment)); 1494 1495 for (i = 0; i < bs->quiesce_counter; i++) { 1496 if (drv->bdrv_co_drain_begin) { 1497 drv->bdrv_co_drain_begin(bs); 1498 } 1499 } 1500 1501 return 0; 1502 open_failed: 1503 bs->drv = NULL; 1504 if (bs->file != NULL) { 1505 bdrv_unref_child(bs, bs->file); 1506 bs->file = NULL; 1507 } 1508 g_free(bs->opaque); 1509 bs->opaque = NULL; 1510 return ret; 1511 } 1512 1513 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name, 1514 int flags, Error **errp) 1515 { 1516 BlockDriverState *bs; 1517 int ret; 1518 1519 bs = bdrv_new(); 1520 bs->open_flags = flags; 1521 bs->explicit_options = qdict_new(); 1522 bs->options = qdict_new(); 1523 bs->opaque = NULL; 1524 1525 update_options_from_flags(bs->options, flags); 1526 1527 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp); 1528 if (ret < 0) { 1529 qobject_unref(bs->explicit_options); 1530 bs->explicit_options = NULL; 1531 qobject_unref(bs->options); 1532 bs->options = NULL; 1533 bdrv_unref(bs); 1534 return NULL; 1535 } 1536 1537 return bs; 1538 } 1539 1540 QemuOptsList bdrv_runtime_opts = { 1541 .name = "bdrv_common", 1542 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head), 1543 .desc = { 1544 { 1545 .name = "node-name", 1546 .type = QEMU_OPT_STRING, 1547 .help = "Node name of the block device node", 1548 }, 1549 { 1550 .name = "driver", 1551 .type = QEMU_OPT_STRING, 1552 .help = "Block driver to use for the node", 1553 }, 1554 { 1555 .name = BDRV_OPT_CACHE_DIRECT, 1556 .type = QEMU_OPT_BOOL, 1557 .help = "Bypass software writeback cache on the host", 1558 }, 1559 { 1560 .name = BDRV_OPT_CACHE_NO_FLUSH, 1561 .type = QEMU_OPT_BOOL, 1562 .help = "Ignore flush requests", 1563 }, 1564 { 1565 .name = BDRV_OPT_READ_ONLY, 1566 .type = QEMU_OPT_BOOL, 1567 .help = "Node is opened in read-only mode", 1568 }, 1569 { 1570 .name = BDRV_OPT_AUTO_READ_ONLY, 1571 .type = QEMU_OPT_BOOL, 1572 .help = "Node can become read-only if opening read-write fails", 1573 }, 1574 { 1575 .name = "detect-zeroes", 1576 .type = QEMU_OPT_STRING, 1577 .help = "try to optimize zero writes (off, on, unmap)", 1578 }, 1579 { 1580 .name = BDRV_OPT_DISCARD, 1581 .type = QEMU_OPT_STRING, 1582 .help = "discard operation (ignore/off, unmap/on)", 1583 }, 1584 { 1585 .name = BDRV_OPT_FORCE_SHARE, 1586 .type = QEMU_OPT_BOOL, 1587 .help = "always accept other writers (default: off)", 1588 }, 1589 { /* end of list */ } 1590 }, 1591 }; 1592 1593 QemuOptsList bdrv_create_opts_simple = { 1594 .name = "simple-create-opts", 1595 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head), 1596 .desc = { 1597 { 1598 .name = BLOCK_OPT_SIZE, 1599 .type = QEMU_OPT_SIZE, 1600 .help = "Virtual disk size" 1601 }, 1602 { 1603 .name = BLOCK_OPT_PREALLOC, 1604 .type = QEMU_OPT_STRING, 1605 .help = "Preallocation mode (allowed values: off)" 1606 }, 1607 { /* end of list */ } 1608 } 1609 }; 1610 1611 /* 1612 * Common part for opening disk images and files 1613 * 1614 * Removes all processed options from *options. 1615 */ 1616 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file, 1617 QDict *options, Error **errp) 1618 { 1619 int ret, open_flags; 1620 const char *filename; 1621 const char *driver_name = NULL; 1622 const char *node_name = NULL; 1623 const char *discard; 1624 QemuOpts *opts; 1625 BlockDriver *drv; 1626 Error *local_err = NULL; 1627 1628 assert(bs->file == NULL); 1629 assert(options != NULL && bs->options != options); 1630 1631 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 1632 if (!qemu_opts_absorb_qdict(opts, options, &local_err)) { 1633 error_propagate(errp, local_err); 1634 ret = -EINVAL; 1635 goto fail_opts; 1636 } 1637 1638 update_flags_from_options(&bs->open_flags, opts); 1639 1640 driver_name = qemu_opt_get(opts, "driver"); 1641 drv = bdrv_find_format(driver_name); 1642 assert(drv != NULL); 1643 1644 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false); 1645 1646 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) { 1647 error_setg(errp, 1648 BDRV_OPT_FORCE_SHARE 1649 "=on can only be used with read-only images"); 1650 ret = -EINVAL; 1651 goto fail_opts; 1652 } 1653 1654 if (file != NULL) { 1655 bdrv_refresh_filename(blk_bs(file)); 1656 filename = blk_bs(file)->filename; 1657 } else { 1658 /* 1659 * Caution: while qdict_get_try_str() is fine, getting 1660 * non-string types would require more care. When @options 1661 * come from -blockdev or blockdev_add, its members are typed 1662 * according to the QAPI schema, but when they come from 1663 * -drive, they're all QString. 1664 */ 1665 filename = qdict_get_try_str(options, "filename"); 1666 } 1667 1668 if (drv->bdrv_needs_filename && (!filename || !filename[0])) { 1669 error_setg(errp, "The '%s' block driver requires a file name", 1670 drv->format_name); 1671 ret = -EINVAL; 1672 goto fail_opts; 1673 } 1674 1675 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags, 1676 drv->format_name); 1677 1678 bs->read_only = !(bs->open_flags & BDRV_O_RDWR); 1679 1680 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) { 1681 if (!bs->read_only && bdrv_is_whitelisted(drv, true)) { 1682 ret = bdrv_apply_auto_read_only(bs, NULL, NULL); 1683 } else { 1684 ret = -ENOTSUP; 1685 } 1686 if (ret < 0) { 1687 error_setg(errp, 1688 !bs->read_only && bdrv_is_whitelisted(drv, true) 1689 ? "Driver '%s' can only be used for read-only devices" 1690 : "Driver '%s' is not whitelisted", 1691 drv->format_name); 1692 goto fail_opts; 1693 } 1694 } 1695 1696 /* bdrv_new() and bdrv_close() make it so */ 1697 assert(atomic_read(&bs->copy_on_read) == 0); 1698 1699 if (bs->open_flags & BDRV_O_COPY_ON_READ) { 1700 if (!bs->read_only) { 1701 bdrv_enable_copy_on_read(bs); 1702 } else { 1703 error_setg(errp, "Can't use copy-on-read on read-only device"); 1704 ret = -EINVAL; 1705 goto fail_opts; 1706 } 1707 } 1708 1709 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD); 1710 if (discard != NULL) { 1711 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) { 1712 error_setg(errp, "Invalid discard option"); 1713 ret = -EINVAL; 1714 goto fail_opts; 1715 } 1716 } 1717 1718 bs->detect_zeroes = 1719 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err); 1720 if (local_err) { 1721 error_propagate(errp, local_err); 1722 ret = -EINVAL; 1723 goto fail_opts; 1724 } 1725 1726 if (filename != NULL) { 1727 pstrcpy(bs->filename, sizeof(bs->filename), filename); 1728 } else { 1729 bs->filename[0] = '\0'; 1730 } 1731 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename); 1732 1733 /* Open the image, either directly or using a protocol */ 1734 open_flags = bdrv_open_flags(bs, bs->open_flags); 1735 node_name = qemu_opt_get(opts, "node-name"); 1736 1737 assert(!drv->bdrv_file_open || file == NULL); 1738 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp); 1739 if (ret < 0) { 1740 goto fail_opts; 1741 } 1742 1743 qemu_opts_del(opts); 1744 return 0; 1745 1746 fail_opts: 1747 qemu_opts_del(opts); 1748 return ret; 1749 } 1750 1751 static QDict *parse_json_filename(const char *filename, Error **errp) 1752 { 1753 QObject *options_obj; 1754 QDict *options; 1755 int ret; 1756 1757 ret = strstart(filename, "json:", &filename); 1758 assert(ret); 1759 1760 options_obj = qobject_from_json(filename, errp); 1761 if (!options_obj) { 1762 error_prepend(errp, "Could not parse the JSON options: "); 1763 return NULL; 1764 } 1765 1766 options = qobject_to(QDict, options_obj); 1767 if (!options) { 1768 qobject_unref(options_obj); 1769 error_setg(errp, "Invalid JSON object given"); 1770 return NULL; 1771 } 1772 1773 qdict_flatten(options); 1774 1775 return options; 1776 } 1777 1778 static void parse_json_protocol(QDict *options, const char **pfilename, 1779 Error **errp) 1780 { 1781 QDict *json_options; 1782 Error *local_err = NULL; 1783 1784 /* Parse json: pseudo-protocol */ 1785 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) { 1786 return; 1787 } 1788 1789 json_options = parse_json_filename(*pfilename, &local_err); 1790 if (local_err) { 1791 error_propagate(errp, local_err); 1792 return; 1793 } 1794 1795 /* Options given in the filename have lower priority than options 1796 * specified directly */ 1797 qdict_join(options, json_options, false); 1798 qobject_unref(json_options); 1799 *pfilename = NULL; 1800 } 1801 1802 /* 1803 * Fills in default options for opening images and converts the legacy 1804 * filename/flags pair to option QDict entries. 1805 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a 1806 * block driver has been specified explicitly. 1807 */ 1808 static int bdrv_fill_options(QDict **options, const char *filename, 1809 int *flags, Error **errp) 1810 { 1811 const char *drvname; 1812 bool protocol = *flags & BDRV_O_PROTOCOL; 1813 bool parse_filename = false; 1814 BlockDriver *drv = NULL; 1815 Error *local_err = NULL; 1816 1817 /* 1818 * Caution: while qdict_get_try_str() is fine, getting non-string 1819 * types would require more care. When @options come from 1820 * -blockdev or blockdev_add, its members are typed according to 1821 * the QAPI schema, but when they come from -drive, they're all 1822 * QString. 1823 */ 1824 drvname = qdict_get_try_str(*options, "driver"); 1825 if (drvname) { 1826 drv = bdrv_find_format(drvname); 1827 if (!drv) { 1828 error_setg(errp, "Unknown driver '%s'", drvname); 1829 return -ENOENT; 1830 } 1831 /* If the user has explicitly specified the driver, this choice should 1832 * override the BDRV_O_PROTOCOL flag */ 1833 protocol = drv->bdrv_file_open; 1834 } 1835 1836 if (protocol) { 1837 *flags |= BDRV_O_PROTOCOL; 1838 } else { 1839 *flags &= ~BDRV_O_PROTOCOL; 1840 } 1841 1842 /* Translate cache options from flags into options */ 1843 update_options_from_flags(*options, *flags); 1844 1845 /* Fetch the file name from the options QDict if necessary */ 1846 if (protocol && filename) { 1847 if (!qdict_haskey(*options, "filename")) { 1848 qdict_put_str(*options, "filename", filename); 1849 parse_filename = true; 1850 } else { 1851 error_setg(errp, "Can't specify 'file' and 'filename' options at " 1852 "the same time"); 1853 return -EINVAL; 1854 } 1855 } 1856 1857 /* Find the right block driver */ 1858 /* See cautionary note on accessing @options above */ 1859 filename = qdict_get_try_str(*options, "filename"); 1860 1861 if (!drvname && protocol) { 1862 if (filename) { 1863 drv = bdrv_find_protocol(filename, parse_filename, errp); 1864 if (!drv) { 1865 return -EINVAL; 1866 } 1867 1868 drvname = drv->format_name; 1869 qdict_put_str(*options, "driver", drvname); 1870 } else { 1871 error_setg(errp, "Must specify either driver or file"); 1872 return -EINVAL; 1873 } 1874 } 1875 1876 assert(drv || !protocol); 1877 1878 /* Driver-specific filename parsing */ 1879 if (drv && drv->bdrv_parse_filename && parse_filename) { 1880 drv->bdrv_parse_filename(filename, *options, &local_err); 1881 if (local_err) { 1882 error_propagate(errp, local_err); 1883 return -EINVAL; 1884 } 1885 1886 if (!drv->bdrv_needs_filename) { 1887 qdict_del(*options, "filename"); 1888 } 1889 } 1890 1891 return 0; 1892 } 1893 1894 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, 1895 uint64_t perm, uint64_t shared, 1896 GSList *ignore_children, 1897 bool *tighten_restrictions, Error **errp); 1898 static void bdrv_child_abort_perm_update(BdrvChild *c); 1899 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared); 1900 1901 typedef struct BlockReopenQueueEntry { 1902 bool prepared; 1903 bool perms_checked; 1904 BDRVReopenState state; 1905 QTAILQ_ENTRY(BlockReopenQueueEntry) entry; 1906 } BlockReopenQueueEntry; 1907 1908 /* 1909 * Return the flags that @bs will have after the reopens in @q have 1910 * successfully completed. If @q is NULL (or @bs is not contained in @q), 1911 * return the current flags. 1912 */ 1913 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs) 1914 { 1915 BlockReopenQueueEntry *entry; 1916 1917 if (q != NULL) { 1918 QTAILQ_FOREACH(entry, q, entry) { 1919 if (entry->state.bs == bs) { 1920 return entry->state.flags; 1921 } 1922 } 1923 } 1924 1925 return bs->open_flags; 1926 } 1927 1928 /* Returns whether the image file can be written to after the reopen queue @q 1929 * has been successfully applied, or right now if @q is NULL. */ 1930 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs, 1931 BlockReopenQueue *q) 1932 { 1933 int flags = bdrv_reopen_get_flags(q, bs); 1934 1935 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR; 1936 } 1937 1938 /* 1939 * Return whether the BDS can be written to. This is not necessarily 1940 * the same as !bdrv_is_read_only(bs), as inactivated images may not 1941 * be written to but do not count as read-only images. 1942 */ 1943 bool bdrv_is_writable(BlockDriverState *bs) 1944 { 1945 return bdrv_is_writable_after_reopen(bs, NULL); 1946 } 1947 1948 static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs, 1949 BdrvChild *c, BdrvChildRole role, 1950 BlockReopenQueue *reopen_queue, 1951 uint64_t parent_perm, uint64_t parent_shared, 1952 uint64_t *nperm, uint64_t *nshared) 1953 { 1954 assert(bs->drv && bs->drv->bdrv_child_perm); 1955 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue, 1956 parent_perm, parent_shared, 1957 nperm, nshared); 1958 /* TODO Take force_share from reopen_queue */ 1959 if (child_bs && child_bs->force_share) { 1960 *nshared = BLK_PERM_ALL; 1961 } 1962 } 1963 1964 /* 1965 * Check whether permissions on this node can be changed in a way that 1966 * @cumulative_perms and @cumulative_shared_perms are the new cumulative 1967 * permissions of all its parents. This involves checking whether all necessary 1968 * permission changes to child nodes can be performed. 1969 * 1970 * Will set *tighten_restrictions to true if and only if new permissions have to 1971 * be taken or currently shared permissions are to be unshared. Otherwise, 1972 * errors are not fatal as long as the caller accepts that the restrictions 1973 * remain tighter than they need to be. The caller still has to abort the 1974 * transaction. 1975 * @tighten_restrictions cannot be used together with @q: When reopening, we may 1976 * encounter fatal errors even though no restrictions are to be tightened. For 1977 * example, changing a node from RW to RO will fail if the WRITE permission is 1978 * to be kept. 1979 * 1980 * A call to this function must always be followed by a call to bdrv_set_perm() 1981 * or bdrv_abort_perm_update(). 1982 */ 1983 static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q, 1984 uint64_t cumulative_perms, 1985 uint64_t cumulative_shared_perms, 1986 GSList *ignore_children, 1987 bool *tighten_restrictions, Error **errp) 1988 { 1989 BlockDriver *drv = bs->drv; 1990 BdrvChild *c; 1991 int ret; 1992 1993 assert(!q || !tighten_restrictions); 1994 1995 if (tighten_restrictions) { 1996 uint64_t current_perms, current_shared; 1997 uint64_t added_perms, removed_shared_perms; 1998 1999 bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared); 2000 2001 added_perms = cumulative_perms & ~current_perms; 2002 removed_shared_perms = current_shared & ~cumulative_shared_perms; 2003 2004 *tighten_restrictions = added_perms || removed_shared_perms; 2005 } 2006 2007 /* Write permissions never work with read-only images */ 2008 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && 2009 !bdrv_is_writable_after_reopen(bs, q)) 2010 { 2011 if (!bdrv_is_writable_after_reopen(bs, NULL)) { 2012 error_setg(errp, "Block node is read-only"); 2013 } else { 2014 uint64_t current_perms, current_shared; 2015 bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared); 2016 if (current_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) { 2017 error_setg(errp, "Cannot make block node read-only, there is " 2018 "a writer on it"); 2019 } else { 2020 error_setg(errp, "Cannot make block node read-only and create " 2021 "a writer on it"); 2022 } 2023 } 2024 2025 return -EPERM; 2026 } 2027 2028 /* Check this node */ 2029 if (!drv) { 2030 return 0; 2031 } 2032 2033 if (drv->bdrv_check_perm) { 2034 return drv->bdrv_check_perm(bs, cumulative_perms, 2035 cumulative_shared_perms, errp); 2036 } 2037 2038 /* Drivers that never have children can omit .bdrv_child_perm() */ 2039 if (!drv->bdrv_child_perm) { 2040 assert(QLIST_EMPTY(&bs->children)); 2041 return 0; 2042 } 2043 2044 /* Check all children */ 2045 QLIST_FOREACH(c, &bs->children, next) { 2046 uint64_t cur_perm, cur_shared; 2047 bool child_tighten_restr; 2048 2049 bdrv_child_perm(bs, c->bs, c, c->role, q, 2050 cumulative_perms, cumulative_shared_perms, 2051 &cur_perm, &cur_shared); 2052 ret = bdrv_child_check_perm(c, q, cur_perm, cur_shared, ignore_children, 2053 tighten_restrictions ? &child_tighten_restr 2054 : NULL, 2055 errp); 2056 if (tighten_restrictions) { 2057 *tighten_restrictions |= child_tighten_restr; 2058 } 2059 if (ret < 0) { 2060 return ret; 2061 } 2062 } 2063 2064 return 0; 2065 } 2066 2067 /* 2068 * Notifies drivers that after a previous bdrv_check_perm() call, the 2069 * permission update is not performed and any preparations made for it (e.g. 2070 * taken file locks) need to be undone. 2071 * 2072 * This function recursively notifies all child nodes. 2073 */ 2074 static void bdrv_abort_perm_update(BlockDriverState *bs) 2075 { 2076 BlockDriver *drv = bs->drv; 2077 BdrvChild *c; 2078 2079 if (!drv) { 2080 return; 2081 } 2082 2083 if (drv->bdrv_abort_perm_update) { 2084 drv->bdrv_abort_perm_update(bs); 2085 } 2086 2087 QLIST_FOREACH(c, &bs->children, next) { 2088 bdrv_child_abort_perm_update(c); 2089 } 2090 } 2091 2092 static void bdrv_set_perm(BlockDriverState *bs, uint64_t cumulative_perms, 2093 uint64_t cumulative_shared_perms) 2094 { 2095 BlockDriver *drv = bs->drv; 2096 BdrvChild *c; 2097 2098 if (!drv) { 2099 return; 2100 } 2101 2102 /* Update this node */ 2103 if (drv->bdrv_set_perm) { 2104 drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms); 2105 } 2106 2107 /* Drivers that never have children can omit .bdrv_child_perm() */ 2108 if (!drv->bdrv_child_perm) { 2109 assert(QLIST_EMPTY(&bs->children)); 2110 return; 2111 } 2112 2113 /* Update all children */ 2114 QLIST_FOREACH(c, &bs->children, next) { 2115 uint64_t cur_perm, cur_shared; 2116 bdrv_child_perm(bs, c->bs, c, c->role, NULL, 2117 cumulative_perms, cumulative_shared_perms, 2118 &cur_perm, &cur_shared); 2119 bdrv_child_set_perm(c, cur_perm, cur_shared); 2120 } 2121 } 2122 2123 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm, 2124 uint64_t *shared_perm) 2125 { 2126 BdrvChild *c; 2127 uint64_t cumulative_perms = 0; 2128 uint64_t cumulative_shared_perms = BLK_PERM_ALL; 2129 2130 QLIST_FOREACH(c, &bs->parents, next_parent) { 2131 cumulative_perms |= c->perm; 2132 cumulative_shared_perms &= c->shared_perm; 2133 } 2134 2135 *perm = cumulative_perms; 2136 *shared_perm = cumulative_shared_perms; 2137 } 2138 2139 static char *bdrv_child_user_desc(BdrvChild *c) 2140 { 2141 if (c->klass->get_parent_desc) { 2142 return c->klass->get_parent_desc(c); 2143 } 2144 2145 return g_strdup("another user"); 2146 } 2147 2148 char *bdrv_perm_names(uint64_t perm) 2149 { 2150 struct perm_name { 2151 uint64_t perm; 2152 const char *name; 2153 } permissions[] = { 2154 { BLK_PERM_CONSISTENT_READ, "consistent read" }, 2155 { BLK_PERM_WRITE, "write" }, 2156 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" }, 2157 { BLK_PERM_RESIZE, "resize" }, 2158 { BLK_PERM_GRAPH_MOD, "change children" }, 2159 { 0, NULL } 2160 }; 2161 2162 GString *result = g_string_sized_new(30); 2163 struct perm_name *p; 2164 2165 for (p = permissions; p->name; p++) { 2166 if (perm & p->perm) { 2167 if (result->len > 0) { 2168 g_string_append(result, ", "); 2169 } 2170 g_string_append(result, p->name); 2171 } 2172 } 2173 2174 return g_string_free(result, FALSE); 2175 } 2176 2177 /* 2178 * Checks whether a new reference to @bs can be added if the new user requires 2179 * @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is 2180 * set, the BdrvChild objects in this list are ignored in the calculations; 2181 * this allows checking permission updates for an existing reference. 2182 * 2183 * See bdrv_check_perm() for the semantics of @tighten_restrictions. 2184 * 2185 * Needs to be followed by a call to either bdrv_set_perm() or 2186 * bdrv_abort_perm_update(). */ 2187 static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, 2188 uint64_t new_used_perm, 2189 uint64_t new_shared_perm, 2190 GSList *ignore_children, 2191 bool *tighten_restrictions, 2192 Error **errp) 2193 { 2194 BdrvChild *c; 2195 uint64_t cumulative_perms = new_used_perm; 2196 uint64_t cumulative_shared_perms = new_shared_perm; 2197 2198 assert(!q || !tighten_restrictions); 2199 2200 /* There is no reason why anyone couldn't tolerate write_unchanged */ 2201 assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED); 2202 2203 QLIST_FOREACH(c, &bs->parents, next_parent) { 2204 if (g_slist_find(ignore_children, c)) { 2205 continue; 2206 } 2207 2208 if ((new_used_perm & c->shared_perm) != new_used_perm) { 2209 char *user = bdrv_child_user_desc(c); 2210 char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm); 2211 2212 if (tighten_restrictions) { 2213 *tighten_restrictions = true; 2214 } 2215 2216 error_setg(errp, "Conflicts with use by %s as '%s', which does not " 2217 "allow '%s' on %s", 2218 user, c->name, perm_names, bdrv_get_node_name(c->bs)); 2219 g_free(user); 2220 g_free(perm_names); 2221 return -EPERM; 2222 } 2223 2224 if ((c->perm & new_shared_perm) != c->perm) { 2225 char *user = bdrv_child_user_desc(c); 2226 char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm); 2227 2228 if (tighten_restrictions) { 2229 *tighten_restrictions = true; 2230 } 2231 2232 error_setg(errp, "Conflicts with use by %s as '%s', which uses " 2233 "'%s' on %s", 2234 user, c->name, perm_names, bdrv_get_node_name(c->bs)); 2235 g_free(user); 2236 g_free(perm_names); 2237 return -EPERM; 2238 } 2239 2240 cumulative_perms |= c->perm; 2241 cumulative_shared_perms &= c->shared_perm; 2242 } 2243 2244 return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms, 2245 ignore_children, tighten_restrictions, errp); 2246 } 2247 2248 /* Needs to be followed by a call to either bdrv_child_set_perm() or 2249 * bdrv_child_abort_perm_update(). */ 2250 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, 2251 uint64_t perm, uint64_t shared, 2252 GSList *ignore_children, 2253 bool *tighten_restrictions, Error **errp) 2254 { 2255 int ret; 2256 2257 ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c); 2258 ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children, 2259 tighten_restrictions, errp); 2260 g_slist_free(ignore_children); 2261 2262 if (ret < 0) { 2263 return ret; 2264 } 2265 2266 if (!c->has_backup_perm) { 2267 c->has_backup_perm = true; 2268 c->backup_perm = c->perm; 2269 c->backup_shared_perm = c->shared_perm; 2270 } 2271 /* 2272 * Note: it's OK if c->has_backup_perm was already set, as we can find the 2273 * same child twice during check_perm procedure 2274 */ 2275 2276 c->perm = perm; 2277 c->shared_perm = shared; 2278 2279 return 0; 2280 } 2281 2282 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared) 2283 { 2284 uint64_t cumulative_perms, cumulative_shared_perms; 2285 2286 c->has_backup_perm = false; 2287 2288 c->perm = perm; 2289 c->shared_perm = shared; 2290 2291 bdrv_get_cumulative_perm(c->bs, &cumulative_perms, 2292 &cumulative_shared_perms); 2293 bdrv_set_perm(c->bs, cumulative_perms, cumulative_shared_perms); 2294 } 2295 2296 static void bdrv_child_abort_perm_update(BdrvChild *c) 2297 { 2298 if (c->has_backup_perm) { 2299 c->perm = c->backup_perm; 2300 c->shared_perm = c->backup_shared_perm; 2301 c->has_backup_perm = false; 2302 } 2303 2304 bdrv_abort_perm_update(c->bs); 2305 } 2306 2307 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, 2308 Error **errp) 2309 { 2310 Error *local_err = NULL; 2311 int ret; 2312 bool tighten_restrictions; 2313 2314 ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL, 2315 &tighten_restrictions, &local_err); 2316 if (ret < 0) { 2317 bdrv_child_abort_perm_update(c); 2318 if (tighten_restrictions) { 2319 error_propagate(errp, local_err); 2320 } else { 2321 /* 2322 * Our caller may intend to only loosen restrictions and 2323 * does not expect this function to fail. Errors are not 2324 * fatal in such a case, so we can just hide them from our 2325 * caller. 2326 */ 2327 error_free(local_err); 2328 ret = 0; 2329 } 2330 return ret; 2331 } 2332 2333 bdrv_child_set_perm(c, perm, shared); 2334 2335 return 0; 2336 } 2337 2338 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp) 2339 { 2340 uint64_t parent_perms, parent_shared; 2341 uint64_t perms, shared; 2342 2343 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared); 2344 bdrv_child_perm(bs, c->bs, c, c->role, NULL, 2345 parent_perms, parent_shared, &perms, &shared); 2346 2347 return bdrv_child_try_set_perm(c, perms, shared, errp); 2348 } 2349 2350 /* 2351 * Default implementation for .bdrv_child_perm() for block filters: 2352 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the 2353 * filtered child. 2354 */ 2355 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c, 2356 BdrvChildRole role, 2357 BlockReopenQueue *reopen_queue, 2358 uint64_t perm, uint64_t shared, 2359 uint64_t *nperm, uint64_t *nshared) 2360 { 2361 *nperm = perm & DEFAULT_PERM_PASSTHROUGH; 2362 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED; 2363 } 2364 2365 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c, 2366 BdrvChildRole role, 2367 BlockReopenQueue *reopen_queue, 2368 uint64_t perm, uint64_t shared, 2369 uint64_t *nperm, uint64_t *nshared) 2370 { 2371 assert(role & BDRV_CHILD_COW); 2372 2373 /* 2374 * We want consistent read from backing files if the parent needs it. 2375 * No other operations are performed on backing files. 2376 */ 2377 perm &= BLK_PERM_CONSISTENT_READ; 2378 2379 /* 2380 * If the parent can deal with changing data, we're okay with a 2381 * writable and resizable backing file. 2382 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? 2383 */ 2384 if (shared & BLK_PERM_WRITE) { 2385 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE; 2386 } else { 2387 shared = 0; 2388 } 2389 2390 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD | 2391 BLK_PERM_WRITE_UNCHANGED; 2392 2393 if (bs->open_flags & BDRV_O_INACTIVE) { 2394 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2395 } 2396 2397 *nperm = perm; 2398 *nshared = shared; 2399 } 2400 2401 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c, 2402 BdrvChildRole role, 2403 BlockReopenQueue *reopen_queue, 2404 uint64_t perm, uint64_t shared, 2405 uint64_t *nperm, uint64_t *nshared) 2406 { 2407 int flags; 2408 2409 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)); 2410 2411 flags = bdrv_reopen_get_flags(reopen_queue, bs); 2412 2413 /* 2414 * Apart from the modifications below, the same permissions are 2415 * forwarded and left alone as for filters 2416 */ 2417 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2418 perm, shared, &perm, &shared); 2419 2420 if (role & BDRV_CHILD_METADATA) { 2421 /* Format drivers may touch metadata even if the guest doesn't write */ 2422 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) { 2423 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2424 } 2425 2426 /* 2427 * bs->file always needs to be consistent because of the 2428 * metadata. We can never allow other users to resize or write 2429 * to it. 2430 */ 2431 if (!(flags & BDRV_O_NO_IO)) { 2432 perm |= BLK_PERM_CONSISTENT_READ; 2433 } 2434 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); 2435 } 2436 2437 if (role & BDRV_CHILD_DATA) { 2438 /* 2439 * Technically, everything in this block is a subset of the 2440 * BDRV_CHILD_METADATA path taken above, and so this could 2441 * be an "else if" branch. However, that is not obvious, and 2442 * this function is not performance critical, therefore we let 2443 * this be an independent "if". 2444 */ 2445 2446 /* 2447 * We cannot allow other users to resize the file because the 2448 * format driver might have some assumptions about the size 2449 * (e.g. because it is stored in metadata, or because the file 2450 * is split into fixed-size data files). 2451 */ 2452 shared &= ~BLK_PERM_RESIZE; 2453 2454 /* 2455 * WRITE_UNCHANGED often cannot be performed as such on the 2456 * data file. For example, the qcow2 driver may still need to 2457 * write copied clusters on copy-on-read. 2458 */ 2459 if (perm & BLK_PERM_WRITE_UNCHANGED) { 2460 perm |= BLK_PERM_WRITE; 2461 } 2462 2463 /* 2464 * If the data file is written to, the format driver may 2465 * expect to be able to resize it by writing beyond the EOF. 2466 */ 2467 if (perm & BLK_PERM_WRITE) { 2468 perm |= BLK_PERM_RESIZE; 2469 } 2470 } 2471 2472 if (bs->open_flags & BDRV_O_INACTIVE) { 2473 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2474 } 2475 2476 *nperm = perm; 2477 *nshared = shared; 2478 } 2479 2480 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c, 2481 BdrvChildRole role, BlockReopenQueue *reopen_queue, 2482 uint64_t perm, uint64_t shared, 2483 uint64_t *nperm, uint64_t *nshared) 2484 { 2485 if (role & BDRV_CHILD_FILTERED) { 2486 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | 2487 BDRV_CHILD_COW))); 2488 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2489 perm, shared, nperm, nshared); 2490 } else if (role & BDRV_CHILD_COW) { 2491 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA))); 2492 bdrv_default_perms_for_cow(bs, c, role, reopen_queue, 2493 perm, shared, nperm, nshared); 2494 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) { 2495 bdrv_default_perms_for_storage(bs, c, role, reopen_queue, 2496 perm, shared, nperm, nshared); 2497 } else { 2498 g_assert_not_reached(); 2499 } 2500 } 2501 2502 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) 2503 { 2504 static const uint64_t permissions[] = { 2505 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ, 2506 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE, 2507 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED, 2508 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE, 2509 [BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD, 2510 }; 2511 2512 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX); 2513 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1); 2514 2515 assert(qapi_perm < BLOCK_PERMISSION__MAX); 2516 2517 return permissions[qapi_perm]; 2518 } 2519 2520 static void bdrv_replace_child_noperm(BdrvChild *child, 2521 BlockDriverState *new_bs) 2522 { 2523 BlockDriverState *old_bs = child->bs; 2524 int new_bs_quiesce_counter; 2525 int drain_saldo; 2526 2527 assert(!child->frozen); 2528 2529 if (old_bs && new_bs) { 2530 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs)); 2531 } 2532 2533 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); 2534 drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter; 2535 2536 /* 2537 * If the new child node is drained but the old one was not, flush 2538 * all outstanding requests to the old child node. 2539 */ 2540 while (drain_saldo > 0 && child->klass->drained_begin) { 2541 bdrv_parent_drained_begin_single(child, true); 2542 drain_saldo--; 2543 } 2544 2545 if (old_bs) { 2546 /* Detach first so that the recursive drain sections coming from @child 2547 * are already gone and we only end the drain sections that came from 2548 * elsewhere. */ 2549 if (child->klass->detach) { 2550 child->klass->detach(child); 2551 } 2552 QLIST_REMOVE(child, next_parent); 2553 } 2554 2555 child->bs = new_bs; 2556 2557 if (new_bs) { 2558 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); 2559 2560 /* 2561 * Detaching the old node may have led to the new node's 2562 * quiesce_counter having been decreased. Not a problem, we 2563 * just need to recognize this here and then invoke 2564 * drained_end appropriately more often. 2565 */ 2566 assert(new_bs->quiesce_counter <= new_bs_quiesce_counter); 2567 drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter; 2568 2569 /* Attach only after starting new drained sections, so that recursive 2570 * drain sections coming from @child don't get an extra .drained_begin 2571 * callback. */ 2572 if (child->klass->attach) { 2573 child->klass->attach(child); 2574 } 2575 } 2576 2577 /* 2578 * If the old child node was drained but the new one is not, allow 2579 * requests to come in only after the new node has been attached. 2580 */ 2581 while (drain_saldo < 0 && child->klass->drained_end) { 2582 bdrv_parent_drained_end_single(child); 2583 drain_saldo++; 2584 } 2585 } 2586 2587 /* 2588 * Updates @child to change its reference to point to @new_bs, including 2589 * checking and applying the necessary permisson updates both to the old node 2590 * and to @new_bs. 2591 * 2592 * NULL is passed as @new_bs for removing the reference before freeing @child. 2593 * 2594 * If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this 2595 * function uses bdrv_set_perm() to update the permissions according to the new 2596 * reference that @new_bs gets. 2597 */ 2598 static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) 2599 { 2600 BlockDriverState *old_bs = child->bs; 2601 uint64_t perm, shared_perm; 2602 2603 bdrv_replace_child_noperm(child, new_bs); 2604 2605 /* 2606 * Start with the new node's permissions. If @new_bs is a (direct 2607 * or indirect) child of @old_bs, we must complete the permission 2608 * update on @new_bs before we loosen the restrictions on @old_bs. 2609 * Otherwise, bdrv_check_perm() on @old_bs would re-initiate 2610 * updating the permissions of @new_bs, and thus not purely loosen 2611 * restrictions. 2612 */ 2613 if (new_bs) { 2614 bdrv_get_cumulative_perm(new_bs, &perm, &shared_perm); 2615 bdrv_set_perm(new_bs, perm, shared_perm); 2616 } 2617 2618 if (old_bs) { 2619 /* Update permissions for old node. This is guaranteed to succeed 2620 * because we're just taking a parent away, so we're loosening 2621 * restrictions. */ 2622 bool tighten_restrictions; 2623 int ret; 2624 2625 bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm); 2626 ret = bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL, 2627 &tighten_restrictions, NULL); 2628 assert(tighten_restrictions == false); 2629 if (ret < 0) { 2630 /* We only tried to loosen restrictions, so errors are not fatal */ 2631 bdrv_abort_perm_update(old_bs); 2632 } else { 2633 bdrv_set_perm(old_bs, perm, shared_perm); 2634 } 2635 2636 /* When the parent requiring a non-default AioContext is removed, the 2637 * node moves back to the main AioContext */ 2638 bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL); 2639 } 2640 } 2641 2642 /* 2643 * This function steals the reference to child_bs from the caller. 2644 * That reference is later dropped by bdrv_root_unref_child(). 2645 * 2646 * On failure NULL is returned, errp is set and the reference to 2647 * child_bs is also dropped. 2648 * 2649 * The caller must hold the AioContext lock @child_bs, but not that of @ctx 2650 * (unless @child_bs is already in @ctx). 2651 */ 2652 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, 2653 const char *child_name, 2654 const BdrvChildClass *child_class, 2655 BdrvChildRole child_role, 2656 AioContext *ctx, 2657 uint64_t perm, uint64_t shared_perm, 2658 void *opaque, Error **errp) 2659 { 2660 BdrvChild *child; 2661 Error *local_err = NULL; 2662 int ret; 2663 2664 ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, NULL, 2665 errp); 2666 if (ret < 0) { 2667 bdrv_abort_perm_update(child_bs); 2668 bdrv_unref(child_bs); 2669 return NULL; 2670 } 2671 2672 child = g_new(BdrvChild, 1); 2673 *child = (BdrvChild) { 2674 .bs = NULL, 2675 .name = g_strdup(child_name), 2676 .klass = child_class, 2677 .role = child_role, 2678 .perm = perm, 2679 .shared_perm = shared_perm, 2680 .opaque = opaque, 2681 }; 2682 2683 /* If the AioContexts don't match, first try to move the subtree of 2684 * child_bs into the AioContext of the new parent. If this doesn't work, 2685 * try moving the parent into the AioContext of child_bs instead. */ 2686 if (bdrv_get_aio_context(child_bs) != ctx) { 2687 ret = bdrv_try_set_aio_context(child_bs, ctx, &local_err); 2688 if (ret < 0 && child_class->can_set_aio_ctx) { 2689 GSList *ignore = g_slist_prepend(NULL, child); 2690 ctx = bdrv_get_aio_context(child_bs); 2691 if (child_class->can_set_aio_ctx(child, ctx, &ignore, NULL)) { 2692 error_free(local_err); 2693 ret = 0; 2694 g_slist_free(ignore); 2695 ignore = g_slist_prepend(NULL, child); 2696 child_class->set_aio_ctx(child, ctx, &ignore); 2697 } 2698 g_slist_free(ignore); 2699 } 2700 if (ret < 0) { 2701 error_propagate(errp, local_err); 2702 g_free(child); 2703 bdrv_abort_perm_update(child_bs); 2704 bdrv_unref(child_bs); 2705 return NULL; 2706 } 2707 } 2708 2709 /* This performs the matching bdrv_set_perm() for the above check. */ 2710 bdrv_replace_child(child, child_bs); 2711 2712 return child; 2713 } 2714 2715 /* 2716 * This function transfers the reference to child_bs from the caller 2717 * to parent_bs. That reference is later dropped by parent_bs on 2718 * bdrv_close() or if someone calls bdrv_unref_child(). 2719 * 2720 * On failure NULL is returned, errp is set and the reference to 2721 * child_bs is also dropped. 2722 * 2723 * If @parent_bs and @child_bs are in different AioContexts, the caller must 2724 * hold the AioContext lock for @child_bs, but not for @parent_bs. 2725 */ 2726 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, 2727 BlockDriverState *child_bs, 2728 const char *child_name, 2729 const BdrvChildClass *child_class, 2730 BdrvChildRole child_role, 2731 Error **errp) 2732 { 2733 BdrvChild *child; 2734 uint64_t perm, shared_perm; 2735 2736 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm); 2737 2738 assert(parent_bs->drv); 2739 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL, 2740 perm, shared_perm, &perm, &shared_perm); 2741 2742 child = bdrv_root_attach_child(child_bs, child_name, child_class, 2743 child_role, bdrv_get_aio_context(parent_bs), 2744 perm, shared_perm, parent_bs, errp); 2745 if (child == NULL) { 2746 return NULL; 2747 } 2748 2749 QLIST_INSERT_HEAD(&parent_bs->children, child, next); 2750 return child; 2751 } 2752 2753 static void bdrv_detach_child(BdrvChild *child) 2754 { 2755 QLIST_SAFE_REMOVE(child, next); 2756 2757 bdrv_replace_child(child, NULL); 2758 2759 g_free(child->name); 2760 g_free(child); 2761 } 2762 2763 void bdrv_root_unref_child(BdrvChild *child) 2764 { 2765 BlockDriverState *child_bs; 2766 2767 child_bs = child->bs; 2768 bdrv_detach_child(child); 2769 bdrv_unref(child_bs); 2770 } 2771 2772 /** 2773 * Clear all inherits_from pointers from children and grandchildren of 2774 * @root that point to @root, where necessary. 2775 */ 2776 static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child) 2777 { 2778 BdrvChild *c; 2779 2780 if (child->bs->inherits_from == root) { 2781 /* 2782 * Remove inherits_from only when the last reference between root and 2783 * child->bs goes away. 2784 */ 2785 QLIST_FOREACH(c, &root->children, next) { 2786 if (c != child && c->bs == child->bs) { 2787 break; 2788 } 2789 } 2790 if (c == NULL) { 2791 child->bs->inherits_from = NULL; 2792 } 2793 } 2794 2795 QLIST_FOREACH(c, &child->bs->children, next) { 2796 bdrv_unset_inherits_from(root, c); 2797 } 2798 } 2799 2800 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child) 2801 { 2802 if (child == NULL) { 2803 return; 2804 } 2805 2806 bdrv_unset_inherits_from(parent, child); 2807 bdrv_root_unref_child(child); 2808 } 2809 2810 2811 static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load) 2812 { 2813 BdrvChild *c; 2814 QLIST_FOREACH(c, &bs->parents, next_parent) { 2815 if (c->klass->change_media) { 2816 c->klass->change_media(c, load); 2817 } 2818 } 2819 } 2820 2821 /* Return true if you can reach parent going through child->inherits_from 2822 * recursively. If parent or child are NULL, return false */ 2823 static bool bdrv_inherits_from_recursive(BlockDriverState *child, 2824 BlockDriverState *parent) 2825 { 2826 while (child && child != parent) { 2827 child = child->inherits_from; 2828 } 2829 2830 return child != NULL; 2831 } 2832 2833 /* 2834 * Return the BdrvChildRole for @bs's backing child. bs->backing is 2835 * mostly used for COW backing children (role = COW), but also for 2836 * filtered children (role = FILTERED | PRIMARY). 2837 */ 2838 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs) 2839 { 2840 if (bs->drv && bs->drv->is_filter) { 2841 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY; 2842 } else { 2843 return BDRV_CHILD_COW; 2844 } 2845 } 2846 2847 /* 2848 * Sets the backing file link of a BDS. A new reference is created; callers 2849 * which don't need their own reference any more must call bdrv_unref(). 2850 */ 2851 void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, 2852 Error **errp) 2853 { 2854 bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) && 2855 bdrv_inherits_from_recursive(backing_hd, bs); 2856 2857 if (bdrv_is_backing_chain_frozen(bs, backing_bs(bs), errp)) { 2858 return; 2859 } 2860 2861 if (backing_hd) { 2862 bdrv_ref(backing_hd); 2863 } 2864 2865 if (bs->backing) { 2866 bdrv_unref_child(bs, bs->backing); 2867 bs->backing = NULL; 2868 } 2869 2870 if (!backing_hd) { 2871 goto out; 2872 } 2873 2874 bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds, 2875 bdrv_backing_role(bs), errp); 2876 /* If backing_hd was already part of bs's backing chain, and 2877 * inherits_from pointed recursively to bs then let's update it to 2878 * point directly to bs (else it will become NULL). */ 2879 if (bs->backing && update_inherits_from) { 2880 backing_hd->inherits_from = bs; 2881 } 2882 2883 out: 2884 bdrv_refresh_limits(bs, NULL); 2885 } 2886 2887 /* 2888 * Opens the backing file for a BlockDriverState if not yet open 2889 * 2890 * bdref_key specifies the key for the image's BlockdevRef in the options QDict. 2891 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 2892 * itself, all options starting with "${bdref_key}." are considered part of the 2893 * BlockdevRef. 2894 * 2895 * TODO Can this be unified with bdrv_open_image()? 2896 */ 2897 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, 2898 const char *bdref_key, Error **errp) 2899 { 2900 char *backing_filename = NULL; 2901 char *bdref_key_dot; 2902 const char *reference = NULL; 2903 int ret = 0; 2904 bool implicit_backing = false; 2905 BlockDriverState *backing_hd; 2906 QDict *options; 2907 QDict *tmp_parent_options = NULL; 2908 Error *local_err = NULL; 2909 2910 if (bs->backing != NULL) { 2911 goto free_exit; 2912 } 2913 2914 /* NULL means an empty set of options */ 2915 if (parent_options == NULL) { 2916 tmp_parent_options = qdict_new(); 2917 parent_options = tmp_parent_options; 2918 } 2919 2920 bs->open_flags &= ~BDRV_O_NO_BACKING; 2921 2922 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 2923 qdict_extract_subqdict(parent_options, &options, bdref_key_dot); 2924 g_free(bdref_key_dot); 2925 2926 /* 2927 * Caution: while qdict_get_try_str() is fine, getting non-string 2928 * types would require more care. When @parent_options come from 2929 * -blockdev or blockdev_add, its members are typed according to 2930 * the QAPI schema, but when they come from -drive, they're all 2931 * QString. 2932 */ 2933 reference = qdict_get_try_str(parent_options, bdref_key); 2934 if (reference || qdict_haskey(options, "file.filename")) { 2935 /* keep backing_filename NULL */ 2936 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { 2937 qobject_unref(options); 2938 goto free_exit; 2939 } else { 2940 if (qdict_size(options) == 0) { 2941 /* If the user specifies options that do not modify the 2942 * backing file's behavior, we might still consider it the 2943 * implicit backing file. But it's easier this way, and 2944 * just specifying some of the backing BDS's options is 2945 * only possible with -drive anyway (otherwise the QAPI 2946 * schema forces the user to specify everything). */ 2947 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file); 2948 } 2949 2950 backing_filename = bdrv_get_full_backing_filename(bs, &local_err); 2951 if (local_err) { 2952 ret = -EINVAL; 2953 error_propagate(errp, local_err); 2954 qobject_unref(options); 2955 goto free_exit; 2956 } 2957 } 2958 2959 if (!bs->drv || !bs->drv->supports_backing) { 2960 ret = -EINVAL; 2961 error_setg(errp, "Driver doesn't support backing files"); 2962 qobject_unref(options); 2963 goto free_exit; 2964 } 2965 2966 if (!reference && 2967 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) { 2968 qdict_put_str(options, "driver", bs->backing_format); 2969 } 2970 2971 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs, 2972 &child_of_bds, bdrv_backing_role(bs), errp); 2973 if (!backing_hd) { 2974 bs->open_flags |= BDRV_O_NO_BACKING; 2975 error_prepend(errp, "Could not open backing file: "); 2976 ret = -EINVAL; 2977 goto free_exit; 2978 } 2979 2980 if (implicit_backing) { 2981 bdrv_refresh_filename(backing_hd); 2982 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 2983 backing_hd->filename); 2984 } 2985 2986 /* Hook up the backing file link; drop our reference, bs owns the 2987 * backing_hd reference now */ 2988 bdrv_set_backing_hd(bs, backing_hd, &local_err); 2989 bdrv_unref(backing_hd); 2990 if (local_err) { 2991 error_propagate(errp, local_err); 2992 ret = -EINVAL; 2993 goto free_exit; 2994 } 2995 2996 qdict_del(parent_options, bdref_key); 2997 2998 free_exit: 2999 g_free(backing_filename); 3000 qobject_unref(tmp_parent_options); 3001 return ret; 3002 } 3003 3004 static BlockDriverState * 3005 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key, 3006 BlockDriverState *parent, const BdrvChildClass *child_class, 3007 BdrvChildRole child_role, bool allow_none, Error **errp) 3008 { 3009 BlockDriverState *bs = NULL; 3010 QDict *image_options; 3011 char *bdref_key_dot; 3012 const char *reference; 3013 3014 assert(child_class != NULL); 3015 3016 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 3017 qdict_extract_subqdict(options, &image_options, bdref_key_dot); 3018 g_free(bdref_key_dot); 3019 3020 /* 3021 * Caution: while qdict_get_try_str() is fine, getting non-string 3022 * types would require more care. When @options come from 3023 * -blockdev or blockdev_add, its members are typed according to 3024 * the QAPI schema, but when they come from -drive, they're all 3025 * QString. 3026 */ 3027 reference = qdict_get_try_str(options, bdref_key); 3028 if (!filename && !reference && !qdict_size(image_options)) { 3029 if (!allow_none) { 3030 error_setg(errp, "A block device must be specified for \"%s\"", 3031 bdref_key); 3032 } 3033 qobject_unref(image_options); 3034 goto done; 3035 } 3036 3037 bs = bdrv_open_inherit(filename, reference, image_options, 0, 3038 parent, child_class, child_role, errp); 3039 if (!bs) { 3040 goto done; 3041 } 3042 3043 done: 3044 qdict_del(options, bdref_key); 3045 return bs; 3046 } 3047 3048 /* 3049 * Opens a disk image whose options are given as BlockdevRef in another block 3050 * device's options. 3051 * 3052 * If allow_none is true, no image will be opened if filename is false and no 3053 * BlockdevRef is given. NULL will be returned, but errp remains unset. 3054 * 3055 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict. 3056 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 3057 * itself, all options starting with "${bdref_key}." are considered part of the 3058 * BlockdevRef. 3059 * 3060 * The BlockdevRef will be removed from the options QDict. 3061 */ 3062 BdrvChild *bdrv_open_child(const char *filename, 3063 QDict *options, const char *bdref_key, 3064 BlockDriverState *parent, 3065 const BdrvChildClass *child_class, 3066 BdrvChildRole child_role, 3067 bool allow_none, Error **errp) 3068 { 3069 BlockDriverState *bs; 3070 3071 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class, 3072 child_role, allow_none, errp); 3073 if (bs == NULL) { 3074 return NULL; 3075 } 3076 3077 return bdrv_attach_child(parent, bs, bdref_key, child_class, child_role, 3078 errp); 3079 } 3080 3081 /* 3082 * TODO Future callers may need to specify parent/child_class in order for 3083 * option inheritance to work. Existing callers use it for the root node. 3084 */ 3085 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp) 3086 { 3087 BlockDriverState *bs = NULL; 3088 QObject *obj = NULL; 3089 QDict *qdict = NULL; 3090 const char *reference = NULL; 3091 Visitor *v = NULL; 3092 3093 if (ref->type == QTYPE_QSTRING) { 3094 reference = ref->u.reference; 3095 } else { 3096 BlockdevOptions *options = &ref->u.definition; 3097 assert(ref->type == QTYPE_QDICT); 3098 3099 v = qobject_output_visitor_new(&obj); 3100 visit_type_BlockdevOptions(v, NULL, &options, &error_abort); 3101 visit_complete(v, &obj); 3102 3103 qdict = qobject_to(QDict, obj); 3104 qdict_flatten(qdict); 3105 3106 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for 3107 * compatibility with other callers) rather than what we want as the 3108 * real defaults. Apply the defaults here instead. */ 3109 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off"); 3110 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off"); 3111 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off"); 3112 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off"); 3113 3114 } 3115 3116 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp); 3117 obj = NULL; 3118 qobject_unref(obj); 3119 visit_free(v); 3120 return bs; 3121 } 3122 3123 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, 3124 int flags, 3125 QDict *snapshot_options, 3126 Error **errp) 3127 { 3128 /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */ 3129 char *tmp_filename = g_malloc0(PATH_MAX + 1); 3130 int64_t total_size; 3131 QemuOpts *opts = NULL; 3132 BlockDriverState *bs_snapshot = NULL; 3133 Error *local_err = NULL; 3134 int ret; 3135 3136 /* if snapshot, we create a temporary backing file and open it 3137 instead of opening 'filename' directly */ 3138 3139 /* Get the required size from the image */ 3140 total_size = bdrv_getlength(bs); 3141 if (total_size < 0) { 3142 error_setg_errno(errp, -total_size, "Could not get image size"); 3143 goto out; 3144 } 3145 3146 /* Create the temporary image */ 3147 ret = get_tmp_filename(tmp_filename, PATH_MAX + 1); 3148 if (ret < 0) { 3149 error_setg_errno(errp, -ret, "Could not get temporary filename"); 3150 goto out; 3151 } 3152 3153 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0, 3154 &error_abort); 3155 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort); 3156 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp); 3157 qemu_opts_del(opts); 3158 if (ret < 0) { 3159 error_prepend(errp, "Could not create temporary overlay '%s': ", 3160 tmp_filename); 3161 goto out; 3162 } 3163 3164 /* Prepare options QDict for the temporary file */ 3165 qdict_put_str(snapshot_options, "file.driver", "file"); 3166 qdict_put_str(snapshot_options, "file.filename", tmp_filename); 3167 qdict_put_str(snapshot_options, "driver", "qcow2"); 3168 3169 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp); 3170 snapshot_options = NULL; 3171 if (!bs_snapshot) { 3172 goto out; 3173 } 3174 3175 /* bdrv_append() consumes a strong reference to bs_snapshot 3176 * (i.e. it will call bdrv_unref() on it) even on error, so in 3177 * order to be able to return one, we have to increase 3178 * bs_snapshot's refcount here */ 3179 bdrv_ref(bs_snapshot); 3180 bdrv_append(bs_snapshot, bs, &local_err); 3181 if (local_err) { 3182 error_propagate(errp, local_err); 3183 bs_snapshot = NULL; 3184 goto out; 3185 } 3186 3187 out: 3188 qobject_unref(snapshot_options); 3189 g_free(tmp_filename); 3190 return bs_snapshot; 3191 } 3192 3193 /* 3194 * Opens a disk image (raw, qcow2, vmdk, ...) 3195 * 3196 * options is a QDict of options to pass to the block drivers, or NULL for an 3197 * empty set of options. The reference to the QDict belongs to the block layer 3198 * after the call (even on failure), so if the caller intends to reuse the 3199 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 3200 * 3201 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there. 3202 * If it is not NULL, the referenced BDS will be reused. 3203 * 3204 * The reference parameter may be used to specify an existing block device which 3205 * should be opened. If specified, neither options nor a filename may be given, 3206 * nor can an existing BDS be reused (that is, *pbs has to be NULL). 3207 */ 3208 static BlockDriverState *bdrv_open_inherit(const char *filename, 3209 const char *reference, 3210 QDict *options, int flags, 3211 BlockDriverState *parent, 3212 const BdrvChildClass *child_class, 3213 BdrvChildRole child_role, 3214 Error **errp) 3215 { 3216 int ret; 3217 BlockBackend *file = NULL; 3218 BlockDriverState *bs; 3219 BlockDriver *drv = NULL; 3220 BdrvChild *child; 3221 const char *drvname; 3222 const char *backing; 3223 Error *local_err = NULL; 3224 QDict *snapshot_options = NULL; 3225 int snapshot_flags = 0; 3226 3227 assert(!child_class || !flags); 3228 assert(!child_class == !parent); 3229 3230 if (reference) { 3231 bool options_non_empty = options ? qdict_size(options) : false; 3232 qobject_unref(options); 3233 3234 if (filename || options_non_empty) { 3235 error_setg(errp, "Cannot reference an existing block device with " 3236 "additional options or a new filename"); 3237 return NULL; 3238 } 3239 3240 bs = bdrv_lookup_bs(reference, reference, errp); 3241 if (!bs) { 3242 return NULL; 3243 } 3244 3245 bdrv_ref(bs); 3246 return bs; 3247 } 3248 3249 bs = bdrv_new(); 3250 3251 /* NULL means an empty set of options */ 3252 if (options == NULL) { 3253 options = qdict_new(); 3254 } 3255 3256 /* json: syntax counts as explicit options, as if in the QDict */ 3257 parse_json_protocol(options, &filename, &local_err); 3258 if (local_err) { 3259 goto fail; 3260 } 3261 3262 bs->explicit_options = qdict_clone_shallow(options); 3263 3264 if (child_class) { 3265 bool parent_is_format; 3266 3267 if (parent->drv) { 3268 parent_is_format = parent->drv->is_format; 3269 } else { 3270 /* 3271 * parent->drv is not set yet because this node is opened for 3272 * (potential) format probing. That means that @parent is going 3273 * to be a format node. 3274 */ 3275 parent_is_format = true; 3276 } 3277 3278 bs->inherits_from = parent; 3279 child_class->inherit_options(child_role, parent_is_format, 3280 &flags, options, 3281 parent->open_flags, parent->options); 3282 } 3283 3284 ret = bdrv_fill_options(&options, filename, &flags, &local_err); 3285 if (ret < 0) { 3286 goto fail; 3287 } 3288 3289 /* 3290 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags. 3291 * Caution: getting a boolean member of @options requires care. 3292 * When @options come from -blockdev or blockdev_add, members are 3293 * typed according to the QAPI schema, but when they come from 3294 * -drive, they're all QString. 3295 */ 3296 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") && 3297 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) { 3298 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR); 3299 } else { 3300 flags &= ~BDRV_O_RDWR; 3301 } 3302 3303 if (flags & BDRV_O_SNAPSHOT) { 3304 snapshot_options = qdict_new(); 3305 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options, 3306 flags, options); 3307 /* Let bdrv_backing_options() override "read-only" */ 3308 qdict_del(options, BDRV_OPT_READ_ONLY); 3309 bdrv_inherited_options(BDRV_CHILD_COW, true, 3310 &flags, options, flags, options); 3311 } 3312 3313 bs->open_flags = flags; 3314 bs->options = options; 3315 options = qdict_clone_shallow(options); 3316 3317 /* Find the right image format driver */ 3318 /* See cautionary note on accessing @options above */ 3319 drvname = qdict_get_try_str(options, "driver"); 3320 if (drvname) { 3321 drv = bdrv_find_format(drvname); 3322 if (!drv) { 3323 error_setg(errp, "Unknown driver: '%s'", drvname); 3324 goto fail; 3325 } 3326 } 3327 3328 assert(drvname || !(flags & BDRV_O_PROTOCOL)); 3329 3330 /* See cautionary note on accessing @options above */ 3331 backing = qdict_get_try_str(options, "backing"); 3332 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL || 3333 (backing && *backing == '\0')) 3334 { 3335 if (backing) { 3336 warn_report("Use of \"backing\": \"\" is deprecated; " 3337 "use \"backing\": null instead"); 3338 } 3339 flags |= BDRV_O_NO_BACKING; 3340 qdict_del(bs->explicit_options, "backing"); 3341 qdict_del(bs->options, "backing"); 3342 qdict_del(options, "backing"); 3343 } 3344 3345 /* Open image file without format layer. This BlockBackend is only used for 3346 * probing, the block drivers will do their own bdrv_open_child() for the 3347 * same BDS, which is why we put the node name back into options. */ 3348 if ((flags & BDRV_O_PROTOCOL) == 0) { 3349 BlockDriverState *file_bs; 3350 3351 file_bs = bdrv_open_child_bs(filename, options, "file", bs, 3352 &child_of_bds, BDRV_CHILD_IMAGE, 3353 true, &local_err); 3354 if (local_err) { 3355 goto fail; 3356 } 3357 if (file_bs != NULL) { 3358 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only 3359 * looking at the header to guess the image format. This works even 3360 * in cases where a guest would not see a consistent state. */ 3361 file = blk_new(bdrv_get_aio_context(file_bs), 0, BLK_PERM_ALL); 3362 blk_insert_bs(file, file_bs, &local_err); 3363 bdrv_unref(file_bs); 3364 if (local_err) { 3365 goto fail; 3366 } 3367 3368 qdict_put_str(options, "file", bdrv_get_node_name(file_bs)); 3369 } 3370 } 3371 3372 /* Image format probing */ 3373 bs->probed = !drv; 3374 if (!drv && file) { 3375 ret = find_image_format(file, filename, &drv, &local_err); 3376 if (ret < 0) { 3377 goto fail; 3378 } 3379 /* 3380 * This option update would logically belong in bdrv_fill_options(), 3381 * but we first need to open bs->file for the probing to work, while 3382 * opening bs->file already requires the (mostly) final set of options 3383 * so that cache mode etc. can be inherited. 3384 * 3385 * Adding the driver later is somewhat ugly, but it's not an option 3386 * that would ever be inherited, so it's correct. We just need to make 3387 * sure to update both bs->options (which has the full effective 3388 * options for bs) and options (which has file.* already removed). 3389 */ 3390 qdict_put_str(bs->options, "driver", drv->format_name); 3391 qdict_put_str(options, "driver", drv->format_name); 3392 } else if (!drv) { 3393 error_setg(errp, "Must specify either driver or file"); 3394 goto fail; 3395 } 3396 3397 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */ 3398 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open); 3399 /* file must be NULL if a protocol BDS is about to be created 3400 * (the inverse results in an error message from bdrv_open_common()) */ 3401 assert(!(flags & BDRV_O_PROTOCOL) || !file); 3402 3403 /* Open the image */ 3404 ret = bdrv_open_common(bs, file, options, &local_err); 3405 if (ret < 0) { 3406 goto fail; 3407 } 3408 3409 if (file) { 3410 blk_unref(file); 3411 file = NULL; 3412 } 3413 3414 /* If there is a backing file, use it */ 3415 if ((flags & BDRV_O_NO_BACKING) == 0) { 3416 ret = bdrv_open_backing_file(bs, options, "backing", &local_err); 3417 if (ret < 0) { 3418 goto close_and_fail; 3419 } 3420 } 3421 3422 /* Remove all children options and references 3423 * from bs->options and bs->explicit_options */ 3424 QLIST_FOREACH(child, &bs->children, next) { 3425 char *child_key_dot; 3426 child_key_dot = g_strdup_printf("%s.", child->name); 3427 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot); 3428 qdict_extract_subqdict(bs->options, NULL, child_key_dot); 3429 qdict_del(bs->explicit_options, child->name); 3430 qdict_del(bs->options, child->name); 3431 g_free(child_key_dot); 3432 } 3433 3434 /* Check if any unknown options were used */ 3435 if (qdict_size(options) != 0) { 3436 const QDictEntry *entry = qdict_first(options); 3437 if (flags & BDRV_O_PROTOCOL) { 3438 error_setg(errp, "Block protocol '%s' doesn't support the option " 3439 "'%s'", drv->format_name, entry->key); 3440 } else { 3441 error_setg(errp, 3442 "Block format '%s' does not support the option '%s'", 3443 drv->format_name, entry->key); 3444 } 3445 3446 goto close_and_fail; 3447 } 3448 3449 bdrv_parent_cb_change_media(bs, true); 3450 3451 qobject_unref(options); 3452 options = NULL; 3453 3454 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the 3455 * temporary snapshot afterwards. */ 3456 if (snapshot_flags) { 3457 BlockDriverState *snapshot_bs; 3458 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags, 3459 snapshot_options, &local_err); 3460 snapshot_options = NULL; 3461 if (local_err) { 3462 goto close_and_fail; 3463 } 3464 /* We are not going to return bs but the overlay on top of it 3465 * (snapshot_bs); thus, we have to drop the strong reference to bs 3466 * (which we obtained by calling bdrv_new()). bs will not be deleted, 3467 * though, because the overlay still has a reference to it. */ 3468 bdrv_unref(bs); 3469 bs = snapshot_bs; 3470 } 3471 3472 return bs; 3473 3474 fail: 3475 blk_unref(file); 3476 qobject_unref(snapshot_options); 3477 qobject_unref(bs->explicit_options); 3478 qobject_unref(bs->options); 3479 qobject_unref(options); 3480 bs->options = NULL; 3481 bs->explicit_options = NULL; 3482 bdrv_unref(bs); 3483 error_propagate(errp, local_err); 3484 return NULL; 3485 3486 close_and_fail: 3487 bdrv_unref(bs); 3488 qobject_unref(snapshot_options); 3489 qobject_unref(options); 3490 error_propagate(errp, local_err); 3491 return NULL; 3492 } 3493 3494 BlockDriverState *bdrv_open(const char *filename, const char *reference, 3495 QDict *options, int flags, Error **errp) 3496 { 3497 return bdrv_open_inherit(filename, reference, options, flags, NULL, 3498 NULL, 0, errp); 3499 } 3500 3501 /* Return true if the NULL-terminated @list contains @str */ 3502 static bool is_str_in_list(const char *str, const char *const *list) 3503 { 3504 if (str && list) { 3505 int i; 3506 for (i = 0; list[i] != NULL; i++) { 3507 if (!strcmp(str, list[i])) { 3508 return true; 3509 } 3510 } 3511 } 3512 return false; 3513 } 3514 3515 /* 3516 * Check that every option set in @bs->options is also set in 3517 * @new_opts. 3518 * 3519 * Options listed in the common_options list and in 3520 * @bs->drv->mutable_opts are skipped. 3521 * 3522 * Return 0 on success, otherwise return -EINVAL and set @errp. 3523 */ 3524 static int bdrv_reset_options_allowed(BlockDriverState *bs, 3525 const QDict *new_opts, Error **errp) 3526 { 3527 const QDictEntry *e; 3528 /* These options are common to all block drivers and are handled 3529 * in bdrv_reopen_prepare() so they can be left out of @new_opts */ 3530 const char *const common_options[] = { 3531 "node-name", "discard", "cache.direct", "cache.no-flush", 3532 "read-only", "auto-read-only", "detect-zeroes", NULL 3533 }; 3534 3535 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) { 3536 if (!qdict_haskey(new_opts, e->key) && 3537 !is_str_in_list(e->key, common_options) && 3538 !is_str_in_list(e->key, bs->drv->mutable_opts)) { 3539 error_setg(errp, "Option '%s' cannot be reset " 3540 "to its default value", e->key); 3541 return -EINVAL; 3542 } 3543 } 3544 3545 return 0; 3546 } 3547 3548 /* 3549 * Returns true if @child can be reached recursively from @bs 3550 */ 3551 static bool bdrv_recurse_has_child(BlockDriverState *bs, 3552 BlockDriverState *child) 3553 { 3554 BdrvChild *c; 3555 3556 if (bs == child) { 3557 return true; 3558 } 3559 3560 QLIST_FOREACH(c, &bs->children, next) { 3561 if (bdrv_recurse_has_child(c->bs, child)) { 3562 return true; 3563 } 3564 } 3565 3566 return false; 3567 } 3568 3569 /* 3570 * Adds a BlockDriverState to a simple queue for an atomic, transactional 3571 * reopen of multiple devices. 3572 * 3573 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT 3574 * already performed, or alternatively may be NULL a new BlockReopenQueue will 3575 * be created and initialized. This newly created BlockReopenQueue should be 3576 * passed back in for subsequent calls that are intended to be of the same 3577 * atomic 'set'. 3578 * 3579 * bs is the BlockDriverState to add to the reopen queue. 3580 * 3581 * options contains the changed options for the associated bs 3582 * (the BlockReopenQueue takes ownership) 3583 * 3584 * flags contains the open flags for the associated bs 3585 * 3586 * returns a pointer to bs_queue, which is either the newly allocated 3587 * bs_queue, or the existing bs_queue being used. 3588 * 3589 * bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple(). 3590 */ 3591 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue, 3592 BlockDriverState *bs, 3593 QDict *options, 3594 const BdrvChildClass *klass, 3595 BdrvChildRole role, 3596 bool parent_is_format, 3597 QDict *parent_options, 3598 int parent_flags, 3599 bool keep_old_opts) 3600 { 3601 assert(bs != NULL); 3602 3603 BlockReopenQueueEntry *bs_entry; 3604 BdrvChild *child; 3605 QDict *old_options, *explicit_options, *options_copy; 3606 int flags; 3607 QemuOpts *opts; 3608 3609 /* Make sure that the caller remembered to use a drained section. This is 3610 * important to avoid graph changes between the recursive queuing here and 3611 * bdrv_reopen_multiple(). */ 3612 assert(bs->quiesce_counter > 0); 3613 3614 if (bs_queue == NULL) { 3615 bs_queue = g_new0(BlockReopenQueue, 1); 3616 QTAILQ_INIT(bs_queue); 3617 } 3618 3619 if (!options) { 3620 options = qdict_new(); 3621 } 3622 3623 /* Check if this BlockDriverState is already in the queue */ 3624 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 3625 if (bs == bs_entry->state.bs) { 3626 break; 3627 } 3628 } 3629 3630 /* 3631 * Precedence of options: 3632 * 1. Explicitly passed in options (highest) 3633 * 2. Retained from explicitly set options of bs 3634 * 3. Inherited from parent node 3635 * 4. Retained from effective options of bs 3636 */ 3637 3638 /* Old explicitly set values (don't overwrite by inherited value) */ 3639 if (bs_entry || keep_old_opts) { 3640 old_options = qdict_clone_shallow(bs_entry ? 3641 bs_entry->state.explicit_options : 3642 bs->explicit_options); 3643 bdrv_join_options(bs, options, old_options); 3644 qobject_unref(old_options); 3645 } 3646 3647 explicit_options = qdict_clone_shallow(options); 3648 3649 /* Inherit from parent node */ 3650 if (parent_options) { 3651 flags = 0; 3652 klass->inherit_options(role, parent_is_format, &flags, options, 3653 parent_flags, parent_options); 3654 } else { 3655 flags = bdrv_get_flags(bs); 3656 } 3657 3658 if (keep_old_opts) { 3659 /* Old values are used for options that aren't set yet */ 3660 old_options = qdict_clone_shallow(bs->options); 3661 bdrv_join_options(bs, options, old_options); 3662 qobject_unref(old_options); 3663 } 3664 3665 /* We have the final set of options so let's update the flags */ 3666 options_copy = qdict_clone_shallow(options); 3667 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 3668 qemu_opts_absorb_qdict(opts, options_copy, NULL); 3669 update_flags_from_options(&flags, opts); 3670 qemu_opts_del(opts); 3671 qobject_unref(options_copy); 3672 3673 /* bdrv_open_inherit() sets and clears some additional flags internally */ 3674 flags &= ~BDRV_O_PROTOCOL; 3675 if (flags & BDRV_O_RDWR) { 3676 flags |= BDRV_O_ALLOW_RDWR; 3677 } 3678 3679 if (!bs_entry) { 3680 bs_entry = g_new0(BlockReopenQueueEntry, 1); 3681 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry); 3682 } else { 3683 qobject_unref(bs_entry->state.options); 3684 qobject_unref(bs_entry->state.explicit_options); 3685 } 3686 3687 bs_entry->state.bs = bs; 3688 bs_entry->state.options = options; 3689 bs_entry->state.explicit_options = explicit_options; 3690 bs_entry->state.flags = flags; 3691 3692 /* This needs to be overwritten in bdrv_reopen_prepare() */ 3693 bs_entry->state.perm = UINT64_MAX; 3694 bs_entry->state.shared_perm = 0; 3695 3696 /* 3697 * If keep_old_opts is false then it means that unspecified 3698 * options must be reset to their original value. We don't allow 3699 * resetting 'backing' but we need to know if the option is 3700 * missing in order to decide if we have to return an error. 3701 */ 3702 if (!keep_old_opts) { 3703 bs_entry->state.backing_missing = 3704 !qdict_haskey(options, "backing") && 3705 !qdict_haskey(options, "backing.driver"); 3706 } 3707 3708 QLIST_FOREACH(child, &bs->children, next) { 3709 QDict *new_child_options = NULL; 3710 bool child_keep_old = keep_old_opts; 3711 3712 /* reopen can only change the options of block devices that were 3713 * implicitly created and inherited options. For other (referenced) 3714 * block devices, a syntax like "backing.foo" results in an error. */ 3715 if (child->bs->inherits_from != bs) { 3716 continue; 3717 } 3718 3719 /* Check if the options contain a child reference */ 3720 if (qdict_haskey(options, child->name)) { 3721 const char *childref = qdict_get_try_str(options, child->name); 3722 /* 3723 * The current child must not be reopened if the child 3724 * reference is null or points to a different node. 3725 */ 3726 if (g_strcmp0(childref, child->bs->node_name)) { 3727 continue; 3728 } 3729 /* 3730 * If the child reference points to the current child then 3731 * reopen it with its existing set of options (note that 3732 * it can still inherit new options from the parent). 3733 */ 3734 child_keep_old = true; 3735 } else { 3736 /* Extract child options ("child-name.*") */ 3737 char *child_key_dot = g_strdup_printf("%s.", child->name); 3738 qdict_extract_subqdict(explicit_options, NULL, child_key_dot); 3739 qdict_extract_subqdict(options, &new_child_options, child_key_dot); 3740 g_free(child_key_dot); 3741 } 3742 3743 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options, 3744 child->klass, child->role, bs->drv->is_format, 3745 options, flags, child_keep_old); 3746 } 3747 3748 return bs_queue; 3749 } 3750 3751 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue, 3752 BlockDriverState *bs, 3753 QDict *options, bool keep_old_opts) 3754 { 3755 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false, 3756 NULL, 0, keep_old_opts); 3757 } 3758 3759 /* 3760 * Reopen multiple BlockDriverStates atomically & transactionally. 3761 * 3762 * The queue passed in (bs_queue) must have been built up previous 3763 * via bdrv_reopen_queue(). 3764 * 3765 * Reopens all BDS specified in the queue, with the appropriate 3766 * flags. All devices are prepared for reopen, and failure of any 3767 * device will cause all device changes to be abandoned, and intermediate 3768 * data cleaned up. 3769 * 3770 * If all devices prepare successfully, then the changes are committed 3771 * to all devices. 3772 * 3773 * All affected nodes must be drained between bdrv_reopen_queue() and 3774 * bdrv_reopen_multiple(). 3775 */ 3776 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) 3777 { 3778 int ret = -1; 3779 BlockReopenQueueEntry *bs_entry, *next; 3780 3781 assert(bs_queue != NULL); 3782 3783 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 3784 assert(bs_entry->state.bs->quiesce_counter > 0); 3785 if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, errp)) { 3786 goto cleanup; 3787 } 3788 bs_entry->prepared = true; 3789 } 3790 3791 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 3792 BDRVReopenState *state = &bs_entry->state; 3793 ret = bdrv_check_perm(state->bs, bs_queue, state->perm, 3794 state->shared_perm, NULL, NULL, errp); 3795 if (ret < 0) { 3796 goto cleanup_perm; 3797 } 3798 /* Check if new_backing_bs would accept the new permissions */ 3799 if (state->replace_backing_bs && state->new_backing_bs) { 3800 uint64_t nperm, nshared; 3801 bdrv_child_perm(state->bs, state->new_backing_bs, 3802 NULL, bdrv_backing_role(state->bs), 3803 bs_queue, state->perm, state->shared_perm, 3804 &nperm, &nshared); 3805 ret = bdrv_check_update_perm(state->new_backing_bs, NULL, 3806 nperm, nshared, NULL, NULL, errp); 3807 if (ret < 0) { 3808 goto cleanup_perm; 3809 } 3810 } 3811 bs_entry->perms_checked = true; 3812 } 3813 3814 /* 3815 * If we reach this point, we have success and just need to apply the 3816 * changes. 3817 * 3818 * Reverse order is used to comfort qcow2 driver: on commit it need to write 3819 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But 3820 * children are usually goes after parents in reopen-queue, so go from last 3821 * to first element. 3822 */ 3823 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 3824 bdrv_reopen_commit(&bs_entry->state); 3825 } 3826 3827 ret = 0; 3828 cleanup_perm: 3829 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 3830 BDRVReopenState *state = &bs_entry->state; 3831 3832 if (!bs_entry->perms_checked) { 3833 continue; 3834 } 3835 3836 if (ret == 0) { 3837 bdrv_set_perm(state->bs, state->perm, state->shared_perm); 3838 } else { 3839 bdrv_abort_perm_update(state->bs); 3840 if (state->replace_backing_bs && state->new_backing_bs) { 3841 bdrv_abort_perm_update(state->new_backing_bs); 3842 } 3843 } 3844 } 3845 3846 if (ret == 0) { 3847 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 3848 BlockDriverState *bs = bs_entry->state.bs; 3849 3850 if (bs->drv->bdrv_reopen_commit_post) 3851 bs->drv->bdrv_reopen_commit_post(&bs_entry->state); 3852 } 3853 } 3854 cleanup: 3855 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 3856 if (ret) { 3857 if (bs_entry->prepared) { 3858 bdrv_reopen_abort(&bs_entry->state); 3859 } 3860 qobject_unref(bs_entry->state.explicit_options); 3861 qobject_unref(bs_entry->state.options); 3862 } 3863 if (bs_entry->state.new_backing_bs) { 3864 bdrv_unref(bs_entry->state.new_backing_bs); 3865 } 3866 g_free(bs_entry); 3867 } 3868 g_free(bs_queue); 3869 3870 return ret; 3871 } 3872 3873 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only, 3874 Error **errp) 3875 { 3876 int ret; 3877 BlockReopenQueue *queue; 3878 QDict *opts = qdict_new(); 3879 3880 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only); 3881 3882 bdrv_subtree_drained_begin(bs); 3883 queue = bdrv_reopen_queue(NULL, bs, opts, true); 3884 ret = bdrv_reopen_multiple(queue, errp); 3885 bdrv_subtree_drained_end(bs); 3886 3887 return ret; 3888 } 3889 3890 static BlockReopenQueueEntry *find_parent_in_reopen_queue(BlockReopenQueue *q, 3891 BdrvChild *c) 3892 { 3893 BlockReopenQueueEntry *entry; 3894 3895 QTAILQ_FOREACH(entry, q, entry) { 3896 BlockDriverState *bs = entry->state.bs; 3897 BdrvChild *child; 3898 3899 QLIST_FOREACH(child, &bs->children, next) { 3900 if (child == c) { 3901 return entry; 3902 } 3903 } 3904 } 3905 3906 return NULL; 3907 } 3908 3909 static void bdrv_reopen_perm(BlockReopenQueue *q, BlockDriverState *bs, 3910 uint64_t *perm, uint64_t *shared) 3911 { 3912 BdrvChild *c; 3913 BlockReopenQueueEntry *parent; 3914 uint64_t cumulative_perms = 0; 3915 uint64_t cumulative_shared_perms = BLK_PERM_ALL; 3916 3917 QLIST_FOREACH(c, &bs->parents, next_parent) { 3918 parent = find_parent_in_reopen_queue(q, c); 3919 if (!parent) { 3920 cumulative_perms |= c->perm; 3921 cumulative_shared_perms &= c->shared_perm; 3922 } else { 3923 uint64_t nperm, nshared; 3924 3925 bdrv_child_perm(parent->state.bs, bs, c, c->role, q, 3926 parent->state.perm, parent->state.shared_perm, 3927 &nperm, &nshared); 3928 3929 cumulative_perms |= nperm; 3930 cumulative_shared_perms &= nshared; 3931 } 3932 } 3933 *perm = cumulative_perms; 3934 *shared = cumulative_shared_perms; 3935 } 3936 3937 static bool bdrv_reopen_can_attach(BlockDriverState *parent, 3938 BdrvChild *child, 3939 BlockDriverState *new_child, 3940 Error **errp) 3941 { 3942 AioContext *parent_ctx = bdrv_get_aio_context(parent); 3943 AioContext *child_ctx = bdrv_get_aio_context(new_child); 3944 GSList *ignore; 3945 bool ret; 3946 3947 ignore = g_slist_prepend(NULL, child); 3948 ret = bdrv_can_set_aio_context(new_child, parent_ctx, &ignore, NULL); 3949 g_slist_free(ignore); 3950 if (ret) { 3951 return ret; 3952 } 3953 3954 ignore = g_slist_prepend(NULL, child); 3955 ret = bdrv_can_set_aio_context(parent, child_ctx, &ignore, errp); 3956 g_slist_free(ignore); 3957 return ret; 3958 } 3959 3960 /* 3961 * Take a BDRVReopenState and check if the value of 'backing' in the 3962 * reopen_state->options QDict is valid or not. 3963 * 3964 * If 'backing' is missing from the QDict then return 0. 3965 * 3966 * If 'backing' contains the node name of the backing file of 3967 * reopen_state->bs then return 0. 3968 * 3969 * If 'backing' contains a different node name (or is null) then check 3970 * whether the current backing file can be replaced with the new one. 3971 * If that's the case then reopen_state->replace_backing_bs is set to 3972 * true and reopen_state->new_backing_bs contains a pointer to the new 3973 * backing BlockDriverState (or NULL). 3974 * 3975 * Return 0 on success, otherwise return < 0 and set @errp. 3976 */ 3977 static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, 3978 Error **errp) 3979 { 3980 BlockDriverState *bs = reopen_state->bs; 3981 BlockDriverState *overlay_bs, *new_backing_bs; 3982 QObject *value; 3983 const char *str; 3984 3985 value = qdict_get(reopen_state->options, "backing"); 3986 if (value == NULL) { 3987 return 0; 3988 } 3989 3990 switch (qobject_type(value)) { 3991 case QTYPE_QNULL: 3992 new_backing_bs = NULL; 3993 break; 3994 case QTYPE_QSTRING: 3995 str = qobject_get_try_str(value); 3996 new_backing_bs = bdrv_lookup_bs(NULL, str, errp); 3997 if (new_backing_bs == NULL) { 3998 return -EINVAL; 3999 } else if (bdrv_recurse_has_child(new_backing_bs, bs)) { 4000 error_setg(errp, "Making '%s' a backing file of '%s' " 4001 "would create a cycle", str, bs->node_name); 4002 return -EINVAL; 4003 } 4004 break; 4005 default: 4006 /* 'backing' does not allow any other data type */ 4007 g_assert_not_reached(); 4008 } 4009 4010 /* 4011 * Check AioContext compatibility so that the bdrv_set_backing_hd() call in 4012 * bdrv_reopen_commit() won't fail. 4013 */ 4014 if (new_backing_bs) { 4015 if (!bdrv_reopen_can_attach(bs, bs->backing, new_backing_bs, errp)) { 4016 return -EINVAL; 4017 } 4018 } 4019 4020 /* 4021 * Find the "actual" backing file by skipping all links that point 4022 * to an implicit node, if any (e.g. a commit filter node). 4023 */ 4024 overlay_bs = bs; 4025 while (backing_bs(overlay_bs) && backing_bs(overlay_bs)->implicit) { 4026 overlay_bs = backing_bs(overlay_bs); 4027 } 4028 4029 /* If we want to replace the backing file we need some extra checks */ 4030 if (new_backing_bs != backing_bs(overlay_bs)) { 4031 /* Check for implicit nodes between bs and its backing file */ 4032 if (bs != overlay_bs) { 4033 error_setg(errp, "Cannot change backing link if '%s' has " 4034 "an implicit backing file", bs->node_name); 4035 return -EPERM; 4036 } 4037 /* Check if the backing link that we want to replace is frozen */ 4038 if (bdrv_is_backing_chain_frozen(overlay_bs, backing_bs(overlay_bs), 4039 errp)) { 4040 return -EPERM; 4041 } 4042 reopen_state->replace_backing_bs = true; 4043 if (new_backing_bs) { 4044 bdrv_ref(new_backing_bs); 4045 reopen_state->new_backing_bs = new_backing_bs; 4046 } 4047 } 4048 4049 return 0; 4050 } 4051 4052 /* 4053 * Prepares a BlockDriverState for reopen. All changes are staged in the 4054 * 'opaque' field of the BDRVReopenState, which is used and allocated by 4055 * the block driver layer .bdrv_reopen_prepare() 4056 * 4057 * bs is the BlockDriverState to reopen 4058 * flags are the new open flags 4059 * queue is the reopen queue 4060 * 4061 * Returns 0 on success, non-zero on error. On error errp will be set 4062 * as well. 4063 * 4064 * On failure, bdrv_reopen_abort() will be called to clean up any data. 4065 * It is the responsibility of the caller to then call the abort() or 4066 * commit() for any other BDS that have been left in a prepare() state 4067 * 4068 */ 4069 int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, 4070 Error **errp) 4071 { 4072 int ret = -1; 4073 int old_flags; 4074 Error *local_err = NULL; 4075 BlockDriver *drv; 4076 QemuOpts *opts; 4077 QDict *orig_reopen_opts; 4078 char *discard = NULL; 4079 bool read_only; 4080 bool drv_prepared = false; 4081 4082 assert(reopen_state != NULL); 4083 assert(reopen_state->bs->drv != NULL); 4084 drv = reopen_state->bs->drv; 4085 4086 /* This function and each driver's bdrv_reopen_prepare() remove 4087 * entries from reopen_state->options as they are processed, so 4088 * we need to make a copy of the original QDict. */ 4089 orig_reopen_opts = qdict_clone_shallow(reopen_state->options); 4090 4091 /* Process generic block layer options */ 4092 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 4093 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, &local_err)) { 4094 error_propagate(errp, local_err); 4095 ret = -EINVAL; 4096 goto error; 4097 } 4098 4099 /* This was already called in bdrv_reopen_queue_child() so the flags 4100 * are up-to-date. This time we simply want to remove the options from 4101 * QemuOpts in order to indicate that they have been processed. */ 4102 old_flags = reopen_state->flags; 4103 update_flags_from_options(&reopen_state->flags, opts); 4104 assert(old_flags == reopen_state->flags); 4105 4106 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD); 4107 if (discard != NULL) { 4108 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) { 4109 error_setg(errp, "Invalid discard option"); 4110 ret = -EINVAL; 4111 goto error; 4112 } 4113 } 4114 4115 reopen_state->detect_zeroes = 4116 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err); 4117 if (local_err) { 4118 error_propagate(errp, local_err); 4119 ret = -EINVAL; 4120 goto error; 4121 } 4122 4123 /* All other options (including node-name and driver) must be unchanged. 4124 * Put them back into the QDict, so that they are checked at the end 4125 * of this function. */ 4126 qemu_opts_to_qdict(opts, reopen_state->options); 4127 4128 /* If we are to stay read-only, do not allow permission change 4129 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is 4130 * not set, or if the BDS still has copy_on_read enabled */ 4131 read_only = !(reopen_state->flags & BDRV_O_RDWR); 4132 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err); 4133 if (local_err) { 4134 error_propagate(errp, local_err); 4135 goto error; 4136 } 4137 4138 /* Calculate required permissions after reopening */ 4139 bdrv_reopen_perm(queue, reopen_state->bs, 4140 &reopen_state->perm, &reopen_state->shared_perm); 4141 4142 ret = bdrv_flush(reopen_state->bs); 4143 if (ret) { 4144 error_setg_errno(errp, -ret, "Error flushing drive"); 4145 goto error; 4146 } 4147 4148 if (drv->bdrv_reopen_prepare) { 4149 /* 4150 * If a driver-specific option is missing, it means that we 4151 * should reset it to its default value. 4152 * But not all options allow that, so we need to check it first. 4153 */ 4154 ret = bdrv_reset_options_allowed(reopen_state->bs, 4155 reopen_state->options, errp); 4156 if (ret) { 4157 goto error; 4158 } 4159 4160 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err); 4161 if (ret) { 4162 if (local_err != NULL) { 4163 error_propagate(errp, local_err); 4164 } else { 4165 bdrv_refresh_filename(reopen_state->bs); 4166 error_setg(errp, "failed while preparing to reopen image '%s'", 4167 reopen_state->bs->filename); 4168 } 4169 goto error; 4170 } 4171 } else { 4172 /* It is currently mandatory to have a bdrv_reopen_prepare() 4173 * handler for each supported drv. */ 4174 error_setg(errp, "Block format '%s' used by node '%s' " 4175 "does not support reopening files", drv->format_name, 4176 bdrv_get_device_or_node_name(reopen_state->bs)); 4177 ret = -1; 4178 goto error; 4179 } 4180 4181 drv_prepared = true; 4182 4183 /* 4184 * We must provide the 'backing' option if the BDS has a backing 4185 * file or if the image file has a backing file name as part of 4186 * its metadata. Otherwise the 'backing' option can be omitted. 4187 */ 4188 if (drv->supports_backing && reopen_state->backing_missing && 4189 (backing_bs(reopen_state->bs) || reopen_state->bs->backing_file[0])) { 4190 error_setg(errp, "backing is missing for '%s'", 4191 reopen_state->bs->node_name); 4192 ret = -EINVAL; 4193 goto error; 4194 } 4195 4196 /* 4197 * Allow changing the 'backing' option. The new value can be 4198 * either a reference to an existing node (using its node name) 4199 * or NULL to simply detach the current backing file. 4200 */ 4201 ret = bdrv_reopen_parse_backing(reopen_state, errp); 4202 if (ret < 0) { 4203 goto error; 4204 } 4205 qdict_del(reopen_state->options, "backing"); 4206 4207 /* Options that are not handled are only okay if they are unchanged 4208 * compared to the old state. It is expected that some options are only 4209 * used for the initial open, but not reopen (e.g. filename) */ 4210 if (qdict_size(reopen_state->options)) { 4211 const QDictEntry *entry = qdict_first(reopen_state->options); 4212 4213 do { 4214 QObject *new = entry->value; 4215 QObject *old = qdict_get(reopen_state->bs->options, entry->key); 4216 4217 /* Allow child references (child_name=node_name) as long as they 4218 * point to the current child (i.e. everything stays the same). */ 4219 if (qobject_type(new) == QTYPE_QSTRING) { 4220 BdrvChild *child; 4221 QLIST_FOREACH(child, &reopen_state->bs->children, next) { 4222 if (!strcmp(child->name, entry->key)) { 4223 break; 4224 } 4225 } 4226 4227 if (child) { 4228 const char *str = qobject_get_try_str(new); 4229 if (!strcmp(child->bs->node_name, str)) { 4230 continue; /* Found child with this name, skip option */ 4231 } 4232 } 4233 } 4234 4235 /* 4236 * TODO: When using -drive to specify blockdev options, all values 4237 * will be strings; however, when using -blockdev, blockdev-add or 4238 * filenames using the json:{} pseudo-protocol, they will be 4239 * correctly typed. 4240 * In contrast, reopening options are (currently) always strings 4241 * (because you can only specify them through qemu-io; all other 4242 * callers do not specify any options). 4243 * Therefore, when using anything other than -drive to create a BDS, 4244 * this cannot detect non-string options as unchanged, because 4245 * qobject_is_equal() always returns false for objects of different 4246 * type. In the future, this should be remedied by correctly typing 4247 * all options. For now, this is not too big of an issue because 4248 * the user can simply omit options which cannot be changed anyway, 4249 * so they will stay unchanged. 4250 */ 4251 if (!qobject_is_equal(new, old)) { 4252 error_setg(errp, "Cannot change the option '%s'", entry->key); 4253 ret = -EINVAL; 4254 goto error; 4255 } 4256 } while ((entry = qdict_next(reopen_state->options, entry))); 4257 } 4258 4259 ret = 0; 4260 4261 /* Restore the original reopen_state->options QDict */ 4262 qobject_unref(reopen_state->options); 4263 reopen_state->options = qobject_ref(orig_reopen_opts); 4264 4265 error: 4266 if (ret < 0 && drv_prepared) { 4267 /* drv->bdrv_reopen_prepare() has succeeded, so we need to 4268 * call drv->bdrv_reopen_abort() before signaling an error 4269 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort() 4270 * when the respective bdrv_reopen_prepare() has failed) */ 4271 if (drv->bdrv_reopen_abort) { 4272 drv->bdrv_reopen_abort(reopen_state); 4273 } 4274 } 4275 qemu_opts_del(opts); 4276 qobject_unref(orig_reopen_opts); 4277 g_free(discard); 4278 return ret; 4279 } 4280 4281 /* 4282 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and 4283 * makes them final by swapping the staging BlockDriverState contents into 4284 * the active BlockDriverState contents. 4285 */ 4286 void bdrv_reopen_commit(BDRVReopenState *reopen_state) 4287 { 4288 BlockDriver *drv; 4289 BlockDriverState *bs; 4290 BdrvChild *child; 4291 4292 assert(reopen_state != NULL); 4293 bs = reopen_state->bs; 4294 drv = bs->drv; 4295 assert(drv != NULL); 4296 4297 /* If there are any driver level actions to take */ 4298 if (drv->bdrv_reopen_commit) { 4299 drv->bdrv_reopen_commit(reopen_state); 4300 } 4301 4302 /* set BDS specific flags now */ 4303 qobject_unref(bs->explicit_options); 4304 qobject_unref(bs->options); 4305 4306 bs->explicit_options = reopen_state->explicit_options; 4307 bs->options = reopen_state->options; 4308 bs->open_flags = reopen_state->flags; 4309 bs->read_only = !(reopen_state->flags & BDRV_O_RDWR); 4310 bs->detect_zeroes = reopen_state->detect_zeroes; 4311 4312 if (reopen_state->replace_backing_bs) { 4313 qdict_del(bs->explicit_options, "backing"); 4314 qdict_del(bs->options, "backing"); 4315 } 4316 4317 /* Remove child references from bs->options and bs->explicit_options. 4318 * Child options were already removed in bdrv_reopen_queue_child() */ 4319 QLIST_FOREACH(child, &bs->children, next) { 4320 qdict_del(bs->explicit_options, child->name); 4321 qdict_del(bs->options, child->name); 4322 } 4323 4324 /* 4325 * Change the backing file if a new one was specified. We do this 4326 * after updating bs->options, so bdrv_refresh_filename() (called 4327 * from bdrv_set_backing_hd()) has the new values. 4328 */ 4329 if (reopen_state->replace_backing_bs) { 4330 BlockDriverState *old_backing_bs = backing_bs(bs); 4331 assert(!old_backing_bs || !old_backing_bs->implicit); 4332 /* Abort the permission update on the backing bs we're detaching */ 4333 if (old_backing_bs) { 4334 bdrv_abort_perm_update(old_backing_bs); 4335 } 4336 bdrv_set_backing_hd(bs, reopen_state->new_backing_bs, &error_abort); 4337 } 4338 4339 bdrv_refresh_limits(bs, NULL); 4340 } 4341 4342 /* 4343 * Abort the reopen, and delete and free the staged changes in 4344 * reopen_state 4345 */ 4346 void bdrv_reopen_abort(BDRVReopenState *reopen_state) 4347 { 4348 BlockDriver *drv; 4349 4350 assert(reopen_state != NULL); 4351 drv = reopen_state->bs->drv; 4352 assert(drv != NULL); 4353 4354 if (drv->bdrv_reopen_abort) { 4355 drv->bdrv_reopen_abort(reopen_state); 4356 } 4357 } 4358 4359 4360 static void bdrv_close(BlockDriverState *bs) 4361 { 4362 BdrvAioNotifier *ban, *ban_next; 4363 BdrvChild *child, *next; 4364 4365 assert(!bs->refcnt); 4366 4367 bdrv_drained_begin(bs); /* complete I/O */ 4368 bdrv_flush(bs); 4369 bdrv_drain(bs); /* in case flush left pending I/O */ 4370 4371 if (bs->drv) { 4372 if (bs->drv->bdrv_close) { 4373 bs->drv->bdrv_close(bs); 4374 } 4375 bs->drv = NULL; 4376 } 4377 4378 QLIST_FOREACH_SAFE(child, &bs->children, next, next) { 4379 bdrv_unref_child(bs, child); 4380 } 4381 4382 bs->backing = NULL; 4383 bs->file = NULL; 4384 g_free(bs->opaque); 4385 bs->opaque = NULL; 4386 atomic_set(&bs->copy_on_read, 0); 4387 bs->backing_file[0] = '\0'; 4388 bs->backing_format[0] = '\0'; 4389 bs->total_sectors = 0; 4390 bs->encrypted = false; 4391 bs->sg = false; 4392 qobject_unref(bs->options); 4393 qobject_unref(bs->explicit_options); 4394 bs->options = NULL; 4395 bs->explicit_options = NULL; 4396 qobject_unref(bs->full_open_options); 4397 bs->full_open_options = NULL; 4398 4399 bdrv_release_named_dirty_bitmaps(bs); 4400 assert(QLIST_EMPTY(&bs->dirty_bitmaps)); 4401 4402 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 4403 g_free(ban); 4404 } 4405 QLIST_INIT(&bs->aio_notifiers); 4406 bdrv_drained_end(bs); 4407 } 4408 4409 void bdrv_close_all(void) 4410 { 4411 assert(job_next(NULL) == NULL); 4412 nbd_export_close_all(); 4413 4414 /* Drop references from requests still in flight, such as canceled block 4415 * jobs whose AIO context has not been polled yet */ 4416 bdrv_drain_all(); 4417 4418 blk_remove_all_bs(); 4419 blockdev_close_all_bdrv_states(); 4420 4421 assert(QTAILQ_EMPTY(&all_bdrv_states)); 4422 } 4423 4424 static bool should_update_child(BdrvChild *c, BlockDriverState *to) 4425 { 4426 GQueue *queue; 4427 GHashTable *found; 4428 bool ret; 4429 4430 if (c->klass->stay_at_node) { 4431 return false; 4432 } 4433 4434 /* If the child @c belongs to the BDS @to, replacing the current 4435 * c->bs by @to would mean to create a loop. 4436 * 4437 * Such a case occurs when appending a BDS to a backing chain. 4438 * For instance, imagine the following chain: 4439 * 4440 * guest device -> node A -> further backing chain... 4441 * 4442 * Now we create a new BDS B which we want to put on top of this 4443 * chain, so we first attach A as its backing node: 4444 * 4445 * node B 4446 * | 4447 * v 4448 * guest device -> node A -> further backing chain... 4449 * 4450 * Finally we want to replace A by B. When doing that, we want to 4451 * replace all pointers to A by pointers to B -- except for the 4452 * pointer from B because (1) that would create a loop, and (2) 4453 * that pointer should simply stay intact: 4454 * 4455 * guest device -> node B 4456 * | 4457 * v 4458 * node A -> further backing chain... 4459 * 4460 * In general, when replacing a node A (c->bs) by a node B (@to), 4461 * if A is a child of B, that means we cannot replace A by B there 4462 * because that would create a loop. Silently detaching A from B 4463 * is also not really an option. So overall just leaving A in 4464 * place there is the most sensible choice. 4465 * 4466 * We would also create a loop in any cases where @c is only 4467 * indirectly referenced by @to. Prevent this by returning false 4468 * if @c is found (by breadth-first search) anywhere in the whole 4469 * subtree of @to. 4470 */ 4471 4472 ret = true; 4473 found = g_hash_table_new(NULL, NULL); 4474 g_hash_table_add(found, to); 4475 queue = g_queue_new(); 4476 g_queue_push_tail(queue, to); 4477 4478 while (!g_queue_is_empty(queue)) { 4479 BlockDriverState *v = g_queue_pop_head(queue); 4480 BdrvChild *c2; 4481 4482 QLIST_FOREACH(c2, &v->children, next) { 4483 if (c2 == c) { 4484 ret = false; 4485 break; 4486 } 4487 4488 if (g_hash_table_contains(found, c2->bs)) { 4489 continue; 4490 } 4491 4492 g_queue_push_tail(queue, c2->bs); 4493 g_hash_table_add(found, c2->bs); 4494 } 4495 } 4496 4497 g_queue_free(queue); 4498 g_hash_table_destroy(found); 4499 4500 return ret; 4501 } 4502 4503 void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, 4504 Error **errp) 4505 { 4506 BdrvChild *c, *next; 4507 GSList *list = NULL, *p; 4508 uint64_t perm = 0, shared = BLK_PERM_ALL; 4509 int ret; 4510 4511 /* Make sure that @from doesn't go away until we have successfully attached 4512 * all of its parents to @to. */ 4513 bdrv_ref(from); 4514 4515 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 4516 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to)); 4517 bdrv_drained_begin(from); 4518 4519 /* Put all parents into @list and calculate their cumulative permissions */ 4520 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { 4521 assert(c->bs == from); 4522 if (!should_update_child(c, to)) { 4523 continue; 4524 } 4525 if (c->frozen) { 4526 error_setg(errp, "Cannot change '%s' link to '%s'", 4527 c->name, from->node_name); 4528 goto out; 4529 } 4530 list = g_slist_prepend(list, c); 4531 perm |= c->perm; 4532 shared &= c->shared_perm; 4533 } 4534 4535 /* Check whether the required permissions can be granted on @to, ignoring 4536 * all BdrvChild in @list so that they can't block themselves. */ 4537 ret = bdrv_check_update_perm(to, NULL, perm, shared, list, NULL, errp); 4538 if (ret < 0) { 4539 bdrv_abort_perm_update(to); 4540 goto out; 4541 } 4542 4543 /* Now actually perform the change. We performed the permission check for 4544 * all elements of @list at once, so set the permissions all at once at the 4545 * very end. */ 4546 for (p = list; p != NULL; p = p->next) { 4547 c = p->data; 4548 4549 bdrv_ref(to); 4550 bdrv_replace_child_noperm(c, to); 4551 bdrv_unref(from); 4552 } 4553 4554 bdrv_get_cumulative_perm(to, &perm, &shared); 4555 bdrv_set_perm(to, perm, shared); 4556 4557 out: 4558 g_slist_free(list); 4559 bdrv_drained_end(from); 4560 bdrv_unref(from); 4561 } 4562 4563 /* 4564 * Add new bs contents at the top of an image chain while the chain is 4565 * live, while keeping required fields on the top layer. 4566 * 4567 * This will modify the BlockDriverState fields, and swap contents 4568 * between bs_new and bs_top. Both bs_new and bs_top are modified. 4569 * 4570 * bs_new must not be attached to a BlockBackend. 4571 * 4572 * This function does not create any image files. 4573 * 4574 * bdrv_append() takes ownership of a bs_new reference and unrefs it because 4575 * that's what the callers commonly need. bs_new will be referenced by the old 4576 * parents of bs_top after bdrv_append() returns. If the caller needs to keep a 4577 * reference of its own, it must call bdrv_ref(). 4578 */ 4579 void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, 4580 Error **errp) 4581 { 4582 Error *local_err = NULL; 4583 4584 bdrv_set_backing_hd(bs_new, bs_top, &local_err); 4585 if (local_err) { 4586 error_propagate(errp, local_err); 4587 goto out; 4588 } 4589 4590 bdrv_replace_node(bs_top, bs_new, &local_err); 4591 if (local_err) { 4592 error_propagate(errp, local_err); 4593 bdrv_set_backing_hd(bs_new, NULL, &error_abort); 4594 goto out; 4595 } 4596 4597 /* bs_new is now referenced by its new parents, we don't need the 4598 * additional reference any more. */ 4599 out: 4600 bdrv_unref(bs_new); 4601 } 4602 4603 static void bdrv_delete(BlockDriverState *bs) 4604 { 4605 assert(bdrv_op_blocker_is_empty(bs)); 4606 assert(!bs->refcnt); 4607 4608 /* remove from list, if necessary */ 4609 if (bs->node_name[0] != '\0') { 4610 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list); 4611 } 4612 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list); 4613 4614 bdrv_close(bs); 4615 4616 g_free(bs); 4617 } 4618 4619 /* 4620 * Run consistency checks on an image 4621 * 4622 * Returns 0 if the check could be completed (it doesn't mean that the image is 4623 * free of errors) or -errno when an internal error occurred. The results of the 4624 * check are stored in res. 4625 */ 4626 static int coroutine_fn bdrv_co_check(BlockDriverState *bs, 4627 BdrvCheckResult *res, BdrvCheckMode fix) 4628 { 4629 if (bs->drv == NULL) { 4630 return -ENOMEDIUM; 4631 } 4632 if (bs->drv->bdrv_co_check == NULL) { 4633 return -ENOTSUP; 4634 } 4635 4636 memset(res, 0, sizeof(*res)); 4637 return bs->drv->bdrv_co_check(bs, res, fix); 4638 } 4639 4640 typedef struct CheckCo { 4641 BlockDriverState *bs; 4642 BdrvCheckResult *res; 4643 BdrvCheckMode fix; 4644 int ret; 4645 } CheckCo; 4646 4647 static void coroutine_fn bdrv_check_co_entry(void *opaque) 4648 { 4649 CheckCo *cco = opaque; 4650 cco->ret = bdrv_co_check(cco->bs, cco->res, cco->fix); 4651 aio_wait_kick(); 4652 } 4653 4654 int bdrv_check(BlockDriverState *bs, 4655 BdrvCheckResult *res, BdrvCheckMode fix) 4656 { 4657 Coroutine *co; 4658 CheckCo cco = { 4659 .bs = bs, 4660 .res = res, 4661 .ret = -EINPROGRESS, 4662 .fix = fix, 4663 }; 4664 4665 if (qemu_in_coroutine()) { 4666 /* Fast-path if already in coroutine context */ 4667 bdrv_check_co_entry(&cco); 4668 } else { 4669 co = qemu_coroutine_create(bdrv_check_co_entry, &cco); 4670 bdrv_coroutine_enter(bs, co); 4671 BDRV_POLL_WHILE(bs, cco.ret == -EINPROGRESS); 4672 } 4673 4674 return cco.ret; 4675 } 4676 4677 /* 4678 * Return values: 4679 * 0 - success 4680 * -EINVAL - backing format specified, but no file 4681 * -ENOSPC - can't update the backing file because no space is left in the 4682 * image file header 4683 * -ENOTSUP - format driver doesn't support changing the backing file 4684 */ 4685 int bdrv_change_backing_file(BlockDriverState *bs, 4686 const char *backing_file, const char *backing_fmt) 4687 { 4688 BlockDriver *drv = bs->drv; 4689 int ret; 4690 4691 if (!drv) { 4692 return -ENOMEDIUM; 4693 } 4694 4695 /* Backing file format doesn't make sense without a backing file */ 4696 if (backing_fmt && !backing_file) { 4697 return -EINVAL; 4698 } 4699 4700 if (drv->bdrv_change_backing_file != NULL) { 4701 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt); 4702 } else { 4703 ret = -ENOTSUP; 4704 } 4705 4706 if (ret == 0) { 4707 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: ""); 4708 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: ""); 4709 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 4710 backing_file ?: ""); 4711 } 4712 return ret; 4713 } 4714 4715 /* 4716 * Finds the image layer in the chain that has 'bs' as its backing file. 4717 * 4718 * active is the current topmost image. 4719 * 4720 * Returns NULL if bs is not found in active's image chain, 4721 * or if active == bs. 4722 * 4723 * Returns the bottommost base image if bs == NULL. 4724 */ 4725 BlockDriverState *bdrv_find_overlay(BlockDriverState *active, 4726 BlockDriverState *bs) 4727 { 4728 while (active && bs != backing_bs(active)) { 4729 active = backing_bs(active); 4730 } 4731 4732 return active; 4733 } 4734 4735 /* Given a BDS, searches for the base layer. */ 4736 BlockDriverState *bdrv_find_base(BlockDriverState *bs) 4737 { 4738 return bdrv_find_overlay(bs, NULL); 4739 } 4740 4741 /* 4742 * Return true if at least one of the backing links between @bs and 4743 * @base is frozen. @errp is set if that's the case. 4744 * @base must be reachable from @bs, or NULL. 4745 */ 4746 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base, 4747 Error **errp) 4748 { 4749 BlockDriverState *i; 4750 4751 for (i = bs; i != base; i = backing_bs(i)) { 4752 if (i->backing && i->backing->frozen) { 4753 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'", 4754 i->backing->name, i->node_name, 4755 backing_bs(i)->node_name); 4756 return true; 4757 } 4758 } 4759 4760 return false; 4761 } 4762 4763 /* 4764 * Freeze all backing links between @bs and @base. 4765 * If any of the links is already frozen the operation is aborted and 4766 * none of the links are modified. 4767 * @base must be reachable from @bs, or NULL. 4768 * Returns 0 on success. On failure returns < 0 and sets @errp. 4769 */ 4770 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base, 4771 Error **errp) 4772 { 4773 BlockDriverState *i; 4774 4775 if (bdrv_is_backing_chain_frozen(bs, base, errp)) { 4776 return -EPERM; 4777 } 4778 4779 for (i = bs; i != base; i = backing_bs(i)) { 4780 if (i->backing && backing_bs(i)->never_freeze) { 4781 error_setg(errp, "Cannot freeze '%s' link to '%s'", 4782 i->backing->name, backing_bs(i)->node_name); 4783 return -EPERM; 4784 } 4785 } 4786 4787 for (i = bs; i != base; i = backing_bs(i)) { 4788 if (i->backing) { 4789 i->backing->frozen = true; 4790 } 4791 } 4792 4793 return 0; 4794 } 4795 4796 /* 4797 * Unfreeze all backing links between @bs and @base. The caller must 4798 * ensure that all links are frozen before using this function. 4799 * @base must be reachable from @bs, or NULL. 4800 */ 4801 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base) 4802 { 4803 BlockDriverState *i; 4804 4805 for (i = bs; i != base; i = backing_bs(i)) { 4806 if (i->backing) { 4807 assert(i->backing->frozen); 4808 i->backing->frozen = false; 4809 } 4810 } 4811 } 4812 4813 /* 4814 * Drops images above 'base' up to and including 'top', and sets the image 4815 * above 'top' to have base as its backing file. 4816 * 4817 * Requires that the overlay to 'top' is opened r/w, so that the backing file 4818 * information in 'bs' can be properly updated. 4819 * 4820 * E.g., this will convert the following chain: 4821 * bottom <- base <- intermediate <- top <- active 4822 * 4823 * to 4824 * 4825 * bottom <- base <- active 4826 * 4827 * It is allowed for bottom==base, in which case it converts: 4828 * 4829 * base <- intermediate <- top <- active 4830 * 4831 * to 4832 * 4833 * base <- active 4834 * 4835 * If backing_file_str is non-NULL, it will be used when modifying top's 4836 * overlay image metadata. 4837 * 4838 * Error conditions: 4839 * if active == top, that is considered an error 4840 * 4841 */ 4842 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, 4843 const char *backing_file_str) 4844 { 4845 BlockDriverState *explicit_top = top; 4846 bool update_inherits_from; 4847 BdrvChild *c, *next; 4848 Error *local_err = NULL; 4849 int ret = -EIO; 4850 4851 bdrv_ref(top); 4852 bdrv_subtree_drained_begin(top); 4853 4854 if (!top->drv || !base->drv) { 4855 goto exit; 4856 } 4857 4858 /* Make sure that base is in the backing chain of top */ 4859 if (!bdrv_chain_contains(top, base)) { 4860 goto exit; 4861 } 4862 4863 /* This function changes all links that point to top and makes 4864 * them point to base. Check that none of them is frozen. */ 4865 QLIST_FOREACH(c, &top->parents, next_parent) { 4866 if (c->frozen) { 4867 goto exit; 4868 } 4869 } 4870 4871 /* If 'base' recursively inherits from 'top' then we should set 4872 * base->inherits_from to top->inherits_from after 'top' and all 4873 * other intermediate nodes have been dropped. 4874 * If 'top' is an implicit node (e.g. "commit_top") we should skip 4875 * it because no one inherits from it. We use explicit_top for that. */ 4876 while (explicit_top && explicit_top->implicit) { 4877 explicit_top = backing_bs(explicit_top); 4878 } 4879 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top); 4880 4881 /* success - we can delete the intermediate states, and link top->base */ 4882 /* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once 4883 * we've figured out how they should work. */ 4884 if (!backing_file_str) { 4885 bdrv_refresh_filename(base); 4886 backing_file_str = base->filename; 4887 } 4888 4889 QLIST_FOREACH_SAFE(c, &top->parents, next_parent, next) { 4890 /* Check whether we are allowed to switch c from top to base */ 4891 GSList *ignore_children = g_slist_prepend(NULL, c); 4892 ret = bdrv_check_update_perm(base, NULL, c->perm, c->shared_perm, 4893 ignore_children, NULL, &local_err); 4894 g_slist_free(ignore_children); 4895 if (ret < 0) { 4896 error_report_err(local_err); 4897 goto exit; 4898 } 4899 4900 /* If so, update the backing file path in the image file */ 4901 if (c->klass->update_filename) { 4902 ret = c->klass->update_filename(c, base, backing_file_str, 4903 &local_err); 4904 if (ret < 0) { 4905 bdrv_abort_perm_update(base); 4906 error_report_err(local_err); 4907 goto exit; 4908 } 4909 } 4910 4911 /* Do the actual switch in the in-memory graph. 4912 * Completes bdrv_check_update_perm() transaction internally. */ 4913 bdrv_ref(base); 4914 bdrv_replace_child(c, base); 4915 bdrv_unref(top); 4916 } 4917 4918 if (update_inherits_from) { 4919 base->inherits_from = explicit_top->inherits_from; 4920 } 4921 4922 ret = 0; 4923 exit: 4924 bdrv_subtree_drained_end(top); 4925 bdrv_unref(top); 4926 return ret; 4927 } 4928 4929 /** 4930 * Length of a allocated file in bytes. Sparse files are counted by actual 4931 * allocated space. Return < 0 if error or unknown. 4932 */ 4933 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs) 4934 { 4935 BlockDriver *drv = bs->drv; 4936 if (!drv) { 4937 return -ENOMEDIUM; 4938 } 4939 if (drv->bdrv_get_allocated_file_size) { 4940 return drv->bdrv_get_allocated_file_size(bs); 4941 } 4942 if (bs->file) { 4943 return bdrv_get_allocated_file_size(bs->file->bs); 4944 } 4945 return -ENOTSUP; 4946 } 4947 4948 /* 4949 * bdrv_measure: 4950 * @drv: Format driver 4951 * @opts: Creation options for new image 4952 * @in_bs: Existing image containing data for new image (may be NULL) 4953 * @errp: Error object 4954 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo()) 4955 * or NULL on error 4956 * 4957 * Calculate file size required to create a new image. 4958 * 4959 * If @in_bs is given then space for allocated clusters and zero clusters 4960 * from that image are included in the calculation. If @opts contains a 4961 * backing file that is shared by @in_bs then backing clusters may be omitted 4962 * from the calculation. 4963 * 4964 * If @in_bs is NULL then the calculation includes no allocated clusters 4965 * unless a preallocation option is given in @opts. 4966 * 4967 * Note that @in_bs may use a different BlockDriver from @drv. 4968 * 4969 * If an error occurs the @errp pointer is set. 4970 */ 4971 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, 4972 BlockDriverState *in_bs, Error **errp) 4973 { 4974 if (!drv->bdrv_measure) { 4975 error_setg(errp, "Block driver '%s' does not support size measurement", 4976 drv->format_name); 4977 return NULL; 4978 } 4979 4980 return drv->bdrv_measure(opts, in_bs, errp); 4981 } 4982 4983 /** 4984 * Return number of sectors on success, -errno on error. 4985 */ 4986 int64_t bdrv_nb_sectors(BlockDriverState *bs) 4987 { 4988 BlockDriver *drv = bs->drv; 4989 4990 if (!drv) 4991 return -ENOMEDIUM; 4992 4993 if (drv->has_variable_length) { 4994 int ret = refresh_total_sectors(bs, bs->total_sectors); 4995 if (ret < 0) { 4996 return ret; 4997 } 4998 } 4999 return bs->total_sectors; 5000 } 5001 5002 /** 5003 * Return length in bytes on success, -errno on error. 5004 * The length is always a multiple of BDRV_SECTOR_SIZE. 5005 */ 5006 int64_t bdrv_getlength(BlockDriverState *bs) 5007 { 5008 int64_t ret = bdrv_nb_sectors(bs); 5009 5010 ret = ret > INT64_MAX / BDRV_SECTOR_SIZE ? -EFBIG : ret; 5011 return ret < 0 ? ret : ret * BDRV_SECTOR_SIZE; 5012 } 5013 5014 /* return 0 as number of sectors if no device present or error */ 5015 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr) 5016 { 5017 int64_t nb_sectors = bdrv_nb_sectors(bs); 5018 5019 *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors; 5020 } 5021 5022 bool bdrv_is_sg(BlockDriverState *bs) 5023 { 5024 return bs->sg; 5025 } 5026 5027 bool bdrv_is_encrypted(BlockDriverState *bs) 5028 { 5029 if (bs->backing && bs->backing->bs->encrypted) { 5030 return true; 5031 } 5032 return bs->encrypted; 5033 } 5034 5035 const char *bdrv_get_format_name(BlockDriverState *bs) 5036 { 5037 return bs->drv ? bs->drv->format_name : NULL; 5038 } 5039 5040 static int qsort_strcmp(const void *a, const void *b) 5041 { 5042 return strcmp(*(char *const *)a, *(char *const *)b); 5043 } 5044 5045 void bdrv_iterate_format(void (*it)(void *opaque, const char *name), 5046 void *opaque, bool read_only) 5047 { 5048 BlockDriver *drv; 5049 int count = 0; 5050 int i; 5051 const char **formats = NULL; 5052 5053 QLIST_FOREACH(drv, &bdrv_drivers, list) { 5054 if (drv->format_name) { 5055 bool found = false; 5056 int i = count; 5057 5058 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) { 5059 continue; 5060 } 5061 5062 while (formats && i && !found) { 5063 found = !strcmp(formats[--i], drv->format_name); 5064 } 5065 5066 if (!found) { 5067 formats = g_renew(const char *, formats, count + 1); 5068 formats[count++] = drv->format_name; 5069 } 5070 } 5071 } 5072 5073 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) { 5074 const char *format_name = block_driver_modules[i].format_name; 5075 5076 if (format_name) { 5077 bool found = false; 5078 int j = count; 5079 5080 if (use_bdrv_whitelist && 5081 !bdrv_format_is_whitelisted(format_name, read_only)) { 5082 continue; 5083 } 5084 5085 while (formats && j && !found) { 5086 found = !strcmp(formats[--j], format_name); 5087 } 5088 5089 if (!found) { 5090 formats = g_renew(const char *, formats, count + 1); 5091 formats[count++] = format_name; 5092 } 5093 } 5094 } 5095 5096 qsort(formats, count, sizeof(formats[0]), qsort_strcmp); 5097 5098 for (i = 0; i < count; i++) { 5099 it(opaque, formats[i]); 5100 } 5101 5102 g_free(formats); 5103 } 5104 5105 /* This function is to find a node in the bs graph */ 5106 BlockDriverState *bdrv_find_node(const char *node_name) 5107 { 5108 BlockDriverState *bs; 5109 5110 assert(node_name); 5111 5112 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 5113 if (!strcmp(node_name, bs->node_name)) { 5114 return bs; 5115 } 5116 } 5117 return NULL; 5118 } 5119 5120 /* Put this QMP function here so it can access the static graph_bdrv_states. */ 5121 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat, 5122 Error **errp) 5123 { 5124 BlockDeviceInfoList *list, *entry; 5125 BlockDriverState *bs; 5126 5127 list = NULL; 5128 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 5129 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp); 5130 if (!info) { 5131 qapi_free_BlockDeviceInfoList(list); 5132 return NULL; 5133 } 5134 entry = g_malloc0(sizeof(*entry)); 5135 entry->value = info; 5136 entry->next = list; 5137 list = entry; 5138 } 5139 5140 return list; 5141 } 5142 5143 #define QAPI_LIST_ADD(list, element) do { \ 5144 typeof(list) _tmp = g_new(typeof(*(list)), 1); \ 5145 _tmp->value = (element); \ 5146 _tmp->next = (list); \ 5147 (list) = _tmp; \ 5148 } while (0) 5149 5150 typedef struct XDbgBlockGraphConstructor { 5151 XDbgBlockGraph *graph; 5152 GHashTable *graph_nodes; 5153 } XDbgBlockGraphConstructor; 5154 5155 static XDbgBlockGraphConstructor *xdbg_graph_new(void) 5156 { 5157 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1); 5158 5159 gr->graph = g_new0(XDbgBlockGraph, 1); 5160 gr->graph_nodes = g_hash_table_new(NULL, NULL); 5161 5162 return gr; 5163 } 5164 5165 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr) 5166 { 5167 XDbgBlockGraph *graph = gr->graph; 5168 5169 g_hash_table_destroy(gr->graph_nodes); 5170 g_free(gr); 5171 5172 return graph; 5173 } 5174 5175 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node) 5176 { 5177 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node); 5178 5179 if (ret != 0) { 5180 return ret; 5181 } 5182 5183 /* 5184 * Start counting from 1, not 0, because 0 interferes with not-found (NULL) 5185 * answer of g_hash_table_lookup. 5186 */ 5187 ret = g_hash_table_size(gr->graph_nodes) + 1; 5188 g_hash_table_insert(gr->graph_nodes, node, (void *)ret); 5189 5190 return ret; 5191 } 5192 5193 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node, 5194 XDbgBlockGraphNodeType type, const char *name) 5195 { 5196 XDbgBlockGraphNode *n; 5197 5198 n = g_new0(XDbgBlockGraphNode, 1); 5199 5200 n->id = xdbg_graph_node_num(gr, node); 5201 n->type = type; 5202 n->name = g_strdup(name); 5203 5204 QAPI_LIST_ADD(gr->graph->nodes, n); 5205 } 5206 5207 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent, 5208 const BdrvChild *child) 5209 { 5210 BlockPermission qapi_perm; 5211 XDbgBlockGraphEdge *edge; 5212 5213 edge = g_new0(XDbgBlockGraphEdge, 1); 5214 5215 edge->parent = xdbg_graph_node_num(gr, parent); 5216 edge->child = xdbg_graph_node_num(gr, child->bs); 5217 edge->name = g_strdup(child->name); 5218 5219 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) { 5220 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm); 5221 5222 if (flag & child->perm) { 5223 QAPI_LIST_ADD(edge->perm, qapi_perm); 5224 } 5225 if (flag & child->shared_perm) { 5226 QAPI_LIST_ADD(edge->shared_perm, qapi_perm); 5227 } 5228 } 5229 5230 QAPI_LIST_ADD(gr->graph->edges, edge); 5231 } 5232 5233 5234 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp) 5235 { 5236 BlockBackend *blk; 5237 BlockJob *job; 5238 BlockDriverState *bs; 5239 BdrvChild *child; 5240 XDbgBlockGraphConstructor *gr = xdbg_graph_new(); 5241 5242 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) { 5243 char *allocated_name = NULL; 5244 const char *name = blk_name(blk); 5245 5246 if (!*name) { 5247 name = allocated_name = blk_get_attached_dev_id(blk); 5248 } 5249 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND, 5250 name); 5251 g_free(allocated_name); 5252 if (blk_root(blk)) { 5253 xdbg_graph_add_edge(gr, blk, blk_root(blk)); 5254 } 5255 } 5256 5257 for (job = block_job_next(NULL); job; job = block_job_next(job)) { 5258 GSList *el; 5259 5260 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB, 5261 job->job.id); 5262 for (el = job->nodes; el; el = el->next) { 5263 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data); 5264 } 5265 } 5266 5267 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 5268 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER, 5269 bs->node_name); 5270 QLIST_FOREACH(child, &bs->children, next) { 5271 xdbg_graph_add_edge(gr, bs, child); 5272 } 5273 } 5274 5275 return xdbg_graph_finalize(gr); 5276 } 5277 5278 BlockDriverState *bdrv_lookup_bs(const char *device, 5279 const char *node_name, 5280 Error **errp) 5281 { 5282 BlockBackend *blk; 5283 BlockDriverState *bs; 5284 5285 if (device) { 5286 blk = blk_by_name(device); 5287 5288 if (blk) { 5289 bs = blk_bs(blk); 5290 if (!bs) { 5291 error_setg(errp, "Device '%s' has no medium", device); 5292 } 5293 5294 return bs; 5295 } 5296 } 5297 5298 if (node_name) { 5299 bs = bdrv_find_node(node_name); 5300 5301 if (bs) { 5302 return bs; 5303 } 5304 } 5305 5306 error_setg(errp, "Cannot find device=%s nor node_name=%s", 5307 device ? device : "", 5308 node_name ? node_name : ""); 5309 return NULL; 5310 } 5311 5312 /* If 'base' is in the same chain as 'top', return true. Otherwise, 5313 * return false. If either argument is NULL, return false. */ 5314 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base) 5315 { 5316 while (top && top != base) { 5317 top = backing_bs(top); 5318 } 5319 5320 return top != NULL; 5321 } 5322 5323 BlockDriverState *bdrv_next_node(BlockDriverState *bs) 5324 { 5325 if (!bs) { 5326 return QTAILQ_FIRST(&graph_bdrv_states); 5327 } 5328 return QTAILQ_NEXT(bs, node_list); 5329 } 5330 5331 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs) 5332 { 5333 if (!bs) { 5334 return QTAILQ_FIRST(&all_bdrv_states); 5335 } 5336 return QTAILQ_NEXT(bs, bs_list); 5337 } 5338 5339 const char *bdrv_get_node_name(const BlockDriverState *bs) 5340 { 5341 return bs->node_name; 5342 } 5343 5344 const char *bdrv_get_parent_name(const BlockDriverState *bs) 5345 { 5346 BdrvChild *c; 5347 const char *name; 5348 5349 /* If multiple parents have a name, just pick the first one. */ 5350 QLIST_FOREACH(c, &bs->parents, next_parent) { 5351 if (c->klass->get_name) { 5352 name = c->klass->get_name(c); 5353 if (name && *name) { 5354 return name; 5355 } 5356 } 5357 } 5358 5359 return NULL; 5360 } 5361 5362 /* TODO check what callers really want: bs->node_name or blk_name() */ 5363 const char *bdrv_get_device_name(const BlockDriverState *bs) 5364 { 5365 return bdrv_get_parent_name(bs) ?: ""; 5366 } 5367 5368 /* This can be used to identify nodes that might not have a device 5369 * name associated. Since node and device names live in the same 5370 * namespace, the result is unambiguous. The exception is if both are 5371 * absent, then this returns an empty (non-null) string. */ 5372 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs) 5373 { 5374 return bdrv_get_parent_name(bs) ?: bs->node_name; 5375 } 5376 5377 int bdrv_get_flags(BlockDriverState *bs) 5378 { 5379 return bs->open_flags; 5380 } 5381 5382 int bdrv_has_zero_init_1(BlockDriverState *bs) 5383 { 5384 return 1; 5385 } 5386 5387 int bdrv_has_zero_init(BlockDriverState *bs) 5388 { 5389 if (!bs->drv) { 5390 return 0; 5391 } 5392 5393 /* If BS is a copy on write image, it is initialized to 5394 the contents of the base image, which may not be zeroes. */ 5395 if (bs->backing) { 5396 return 0; 5397 } 5398 if (bs->drv->bdrv_has_zero_init) { 5399 return bs->drv->bdrv_has_zero_init(bs); 5400 } 5401 if (bs->file && bs->drv->is_filter) { 5402 return bdrv_has_zero_init(bs->file->bs); 5403 } 5404 5405 /* safe default */ 5406 return 0; 5407 } 5408 5409 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs) 5410 { 5411 if (!(bs->open_flags & BDRV_O_UNMAP)) { 5412 return false; 5413 } 5414 5415 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP; 5416 } 5417 5418 void bdrv_get_backing_filename(BlockDriverState *bs, 5419 char *filename, int filename_size) 5420 { 5421 pstrcpy(filename, filename_size, bs->backing_file); 5422 } 5423 5424 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) 5425 { 5426 BlockDriver *drv = bs->drv; 5427 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */ 5428 if (!drv) { 5429 return -ENOMEDIUM; 5430 } 5431 if (!drv->bdrv_get_info) { 5432 if (bs->file && drv->is_filter) { 5433 return bdrv_get_info(bs->file->bs, bdi); 5434 } 5435 return -ENOTSUP; 5436 } 5437 memset(bdi, 0, sizeof(*bdi)); 5438 return drv->bdrv_get_info(bs, bdi); 5439 } 5440 5441 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, 5442 Error **errp) 5443 { 5444 BlockDriver *drv = bs->drv; 5445 if (drv && drv->bdrv_get_specific_info) { 5446 return drv->bdrv_get_specific_info(bs, errp); 5447 } 5448 return NULL; 5449 } 5450 5451 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs) 5452 { 5453 BlockDriver *drv = bs->drv; 5454 if (!drv || !drv->bdrv_get_specific_stats) { 5455 return NULL; 5456 } 5457 return drv->bdrv_get_specific_stats(bs); 5458 } 5459 5460 void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event) 5461 { 5462 if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) { 5463 return; 5464 } 5465 5466 bs->drv->bdrv_debug_event(bs, event); 5467 } 5468 5469 static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs) 5470 { 5471 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) { 5472 if (bs->file) { 5473 bs = bs->file->bs; 5474 continue; 5475 } 5476 5477 if (bs->drv->is_filter && bs->backing) { 5478 bs = bs->backing->bs; 5479 continue; 5480 } 5481 5482 break; 5483 } 5484 5485 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) { 5486 assert(bs->drv->bdrv_debug_remove_breakpoint); 5487 return bs; 5488 } 5489 5490 return NULL; 5491 } 5492 5493 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event, 5494 const char *tag) 5495 { 5496 bs = bdrv_find_debug_node(bs); 5497 if (bs) { 5498 return bs->drv->bdrv_debug_breakpoint(bs, event, tag); 5499 } 5500 5501 return -ENOTSUP; 5502 } 5503 5504 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag) 5505 { 5506 bs = bdrv_find_debug_node(bs); 5507 if (bs) { 5508 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag); 5509 } 5510 5511 return -ENOTSUP; 5512 } 5513 5514 int bdrv_debug_resume(BlockDriverState *bs, const char *tag) 5515 { 5516 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) { 5517 bs = bs->file ? bs->file->bs : NULL; 5518 } 5519 5520 if (bs && bs->drv && bs->drv->bdrv_debug_resume) { 5521 return bs->drv->bdrv_debug_resume(bs, tag); 5522 } 5523 5524 return -ENOTSUP; 5525 } 5526 5527 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag) 5528 { 5529 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) { 5530 bs = bs->file ? bs->file->bs : NULL; 5531 } 5532 5533 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) { 5534 return bs->drv->bdrv_debug_is_suspended(bs, tag); 5535 } 5536 5537 return false; 5538 } 5539 5540 /* backing_file can either be relative, or absolute, or a protocol. If it is 5541 * relative, it must be relative to the chain. So, passing in bs->filename 5542 * from a BDS as backing_file should not be done, as that may be relative to 5543 * the CWD rather than the chain. */ 5544 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, 5545 const char *backing_file) 5546 { 5547 char *filename_full = NULL; 5548 char *backing_file_full = NULL; 5549 char *filename_tmp = NULL; 5550 int is_protocol = 0; 5551 BlockDriverState *curr_bs = NULL; 5552 BlockDriverState *retval = NULL; 5553 5554 if (!bs || !bs->drv || !backing_file) { 5555 return NULL; 5556 } 5557 5558 filename_full = g_malloc(PATH_MAX); 5559 backing_file_full = g_malloc(PATH_MAX); 5560 5561 is_protocol = path_has_protocol(backing_file); 5562 5563 for (curr_bs = bs; curr_bs->backing; curr_bs = curr_bs->backing->bs) { 5564 5565 /* If either of the filename paths is actually a protocol, then 5566 * compare unmodified paths; otherwise make paths relative */ 5567 if (is_protocol || path_has_protocol(curr_bs->backing_file)) { 5568 char *backing_file_full_ret; 5569 5570 if (strcmp(backing_file, curr_bs->backing_file) == 0) { 5571 retval = curr_bs->backing->bs; 5572 break; 5573 } 5574 /* Also check against the full backing filename for the image */ 5575 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs, 5576 NULL); 5577 if (backing_file_full_ret) { 5578 bool equal = strcmp(backing_file, backing_file_full_ret) == 0; 5579 g_free(backing_file_full_ret); 5580 if (equal) { 5581 retval = curr_bs->backing->bs; 5582 break; 5583 } 5584 } 5585 } else { 5586 /* If not an absolute filename path, make it relative to the current 5587 * image's filename path */ 5588 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file, 5589 NULL); 5590 /* We are going to compare canonicalized absolute pathnames */ 5591 if (!filename_tmp || !realpath(filename_tmp, filename_full)) { 5592 g_free(filename_tmp); 5593 continue; 5594 } 5595 g_free(filename_tmp); 5596 5597 /* We need to make sure the backing filename we are comparing against 5598 * is relative to the current image filename (or absolute) */ 5599 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL); 5600 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) { 5601 g_free(filename_tmp); 5602 continue; 5603 } 5604 g_free(filename_tmp); 5605 5606 if (strcmp(backing_file_full, filename_full) == 0) { 5607 retval = curr_bs->backing->bs; 5608 break; 5609 } 5610 } 5611 } 5612 5613 g_free(filename_full); 5614 g_free(backing_file_full); 5615 return retval; 5616 } 5617 5618 void bdrv_init(void) 5619 { 5620 module_call_init(MODULE_INIT_BLOCK); 5621 } 5622 5623 void bdrv_init_with_whitelist(void) 5624 { 5625 use_bdrv_whitelist = 1; 5626 bdrv_init(); 5627 } 5628 5629 static void coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, 5630 Error **errp) 5631 { 5632 BdrvChild *child, *parent; 5633 uint64_t perm, shared_perm; 5634 Error *local_err = NULL; 5635 int ret; 5636 BdrvDirtyBitmap *bm; 5637 5638 if (!bs->drv) { 5639 return; 5640 } 5641 5642 QLIST_FOREACH(child, &bs->children, next) { 5643 bdrv_co_invalidate_cache(child->bs, &local_err); 5644 if (local_err) { 5645 error_propagate(errp, local_err); 5646 return; 5647 } 5648 } 5649 5650 /* 5651 * Update permissions, they may differ for inactive nodes. 5652 * 5653 * Note that the required permissions of inactive images are always a 5654 * subset of the permissions required after activating the image. This 5655 * allows us to just get the permissions upfront without restricting 5656 * drv->bdrv_invalidate_cache(). 5657 * 5658 * It also means that in error cases, we don't have to try and revert to 5659 * the old permissions (which is an operation that could fail, too). We can 5660 * just keep the extended permissions for the next time that an activation 5661 * of the image is tried. 5662 */ 5663 if (bs->open_flags & BDRV_O_INACTIVE) { 5664 bs->open_flags &= ~BDRV_O_INACTIVE; 5665 bdrv_get_cumulative_perm(bs, &perm, &shared_perm); 5666 ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, &local_err); 5667 if (ret < 0) { 5668 bs->open_flags |= BDRV_O_INACTIVE; 5669 error_propagate(errp, local_err); 5670 return; 5671 } 5672 bdrv_set_perm(bs, perm, shared_perm); 5673 5674 if (bs->drv->bdrv_co_invalidate_cache) { 5675 bs->drv->bdrv_co_invalidate_cache(bs, &local_err); 5676 if (local_err) { 5677 bs->open_flags |= BDRV_O_INACTIVE; 5678 error_propagate(errp, local_err); 5679 return; 5680 } 5681 } 5682 5683 FOR_EACH_DIRTY_BITMAP(bs, bm) { 5684 bdrv_dirty_bitmap_skip_store(bm, false); 5685 } 5686 5687 ret = refresh_total_sectors(bs, bs->total_sectors); 5688 if (ret < 0) { 5689 bs->open_flags |= BDRV_O_INACTIVE; 5690 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 5691 return; 5692 } 5693 } 5694 5695 QLIST_FOREACH(parent, &bs->parents, next_parent) { 5696 if (parent->klass->activate) { 5697 parent->klass->activate(parent, &local_err); 5698 if (local_err) { 5699 bs->open_flags |= BDRV_O_INACTIVE; 5700 error_propagate(errp, local_err); 5701 return; 5702 } 5703 } 5704 } 5705 } 5706 5707 typedef struct InvalidateCacheCo { 5708 BlockDriverState *bs; 5709 Error **errp; 5710 bool done; 5711 } InvalidateCacheCo; 5712 5713 static void coroutine_fn bdrv_invalidate_cache_co_entry(void *opaque) 5714 { 5715 InvalidateCacheCo *ico = opaque; 5716 bdrv_co_invalidate_cache(ico->bs, ico->errp); 5717 ico->done = true; 5718 aio_wait_kick(); 5719 } 5720 5721 void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp) 5722 { 5723 Coroutine *co; 5724 InvalidateCacheCo ico = { 5725 .bs = bs, 5726 .done = false, 5727 .errp = errp 5728 }; 5729 5730 if (qemu_in_coroutine()) { 5731 /* Fast-path if already in coroutine context */ 5732 bdrv_invalidate_cache_co_entry(&ico); 5733 } else { 5734 co = qemu_coroutine_create(bdrv_invalidate_cache_co_entry, &ico); 5735 bdrv_coroutine_enter(bs, co); 5736 BDRV_POLL_WHILE(bs, !ico.done); 5737 } 5738 } 5739 5740 void bdrv_invalidate_cache_all(Error **errp) 5741 { 5742 BlockDriverState *bs; 5743 Error *local_err = NULL; 5744 BdrvNextIterator it; 5745 5746 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 5747 AioContext *aio_context = bdrv_get_aio_context(bs); 5748 5749 aio_context_acquire(aio_context); 5750 bdrv_invalidate_cache(bs, &local_err); 5751 aio_context_release(aio_context); 5752 if (local_err) { 5753 error_propagate(errp, local_err); 5754 bdrv_next_cleanup(&it); 5755 return; 5756 } 5757 } 5758 } 5759 5760 static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active) 5761 { 5762 BdrvChild *parent; 5763 5764 QLIST_FOREACH(parent, &bs->parents, next_parent) { 5765 if (parent->klass->parent_is_bds) { 5766 BlockDriverState *parent_bs = parent->opaque; 5767 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) { 5768 return true; 5769 } 5770 } 5771 } 5772 5773 return false; 5774 } 5775 5776 static int bdrv_inactivate_recurse(BlockDriverState *bs) 5777 { 5778 BdrvChild *child, *parent; 5779 bool tighten_restrictions; 5780 uint64_t perm, shared_perm; 5781 int ret; 5782 5783 if (!bs->drv) { 5784 return -ENOMEDIUM; 5785 } 5786 5787 /* Make sure that we don't inactivate a child before its parent. 5788 * It will be covered by recursion from the yet active parent. */ 5789 if (bdrv_has_bds_parent(bs, true)) { 5790 return 0; 5791 } 5792 5793 assert(!(bs->open_flags & BDRV_O_INACTIVE)); 5794 5795 /* Inactivate this node */ 5796 if (bs->drv->bdrv_inactivate) { 5797 ret = bs->drv->bdrv_inactivate(bs); 5798 if (ret < 0) { 5799 return ret; 5800 } 5801 } 5802 5803 QLIST_FOREACH(parent, &bs->parents, next_parent) { 5804 if (parent->klass->inactivate) { 5805 ret = parent->klass->inactivate(parent); 5806 if (ret < 0) { 5807 return ret; 5808 } 5809 } 5810 } 5811 5812 bs->open_flags |= BDRV_O_INACTIVE; 5813 5814 /* Update permissions, they may differ for inactive nodes */ 5815 bdrv_get_cumulative_perm(bs, &perm, &shared_perm); 5816 ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, 5817 &tighten_restrictions, NULL); 5818 assert(tighten_restrictions == false); 5819 if (ret < 0) { 5820 /* We only tried to loosen restrictions, so errors are not fatal */ 5821 bdrv_abort_perm_update(bs); 5822 } else { 5823 bdrv_set_perm(bs, perm, shared_perm); 5824 } 5825 5826 5827 /* Recursively inactivate children */ 5828 QLIST_FOREACH(child, &bs->children, next) { 5829 ret = bdrv_inactivate_recurse(child->bs); 5830 if (ret < 0) { 5831 return ret; 5832 } 5833 } 5834 5835 return 0; 5836 } 5837 5838 int bdrv_inactivate_all(void) 5839 { 5840 BlockDriverState *bs = NULL; 5841 BdrvNextIterator it; 5842 int ret = 0; 5843 GSList *aio_ctxs = NULL, *ctx; 5844 5845 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 5846 AioContext *aio_context = bdrv_get_aio_context(bs); 5847 5848 if (!g_slist_find(aio_ctxs, aio_context)) { 5849 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context); 5850 aio_context_acquire(aio_context); 5851 } 5852 } 5853 5854 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 5855 /* Nodes with BDS parents are covered by recursion from the last 5856 * parent that gets inactivated. Don't inactivate them a second 5857 * time if that has already happened. */ 5858 if (bdrv_has_bds_parent(bs, false)) { 5859 continue; 5860 } 5861 ret = bdrv_inactivate_recurse(bs); 5862 if (ret < 0) { 5863 bdrv_next_cleanup(&it); 5864 goto out; 5865 } 5866 } 5867 5868 out: 5869 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) { 5870 AioContext *aio_context = ctx->data; 5871 aio_context_release(aio_context); 5872 } 5873 g_slist_free(aio_ctxs); 5874 5875 return ret; 5876 } 5877 5878 /**************************************************************/ 5879 /* removable device support */ 5880 5881 /** 5882 * Return TRUE if the media is present 5883 */ 5884 bool bdrv_is_inserted(BlockDriverState *bs) 5885 { 5886 BlockDriver *drv = bs->drv; 5887 BdrvChild *child; 5888 5889 if (!drv) { 5890 return false; 5891 } 5892 if (drv->bdrv_is_inserted) { 5893 return drv->bdrv_is_inserted(bs); 5894 } 5895 QLIST_FOREACH(child, &bs->children, next) { 5896 if (!bdrv_is_inserted(child->bs)) { 5897 return false; 5898 } 5899 } 5900 return true; 5901 } 5902 5903 /** 5904 * If eject_flag is TRUE, eject the media. Otherwise, close the tray 5905 */ 5906 void bdrv_eject(BlockDriverState *bs, bool eject_flag) 5907 { 5908 BlockDriver *drv = bs->drv; 5909 5910 if (drv && drv->bdrv_eject) { 5911 drv->bdrv_eject(bs, eject_flag); 5912 } 5913 } 5914 5915 /** 5916 * Lock or unlock the media (if it is locked, the user won't be able 5917 * to eject it manually). 5918 */ 5919 void bdrv_lock_medium(BlockDriverState *bs, bool locked) 5920 { 5921 BlockDriver *drv = bs->drv; 5922 5923 trace_bdrv_lock_medium(bs, locked); 5924 5925 if (drv && drv->bdrv_lock_medium) { 5926 drv->bdrv_lock_medium(bs, locked); 5927 } 5928 } 5929 5930 /* Get a reference to bs */ 5931 void bdrv_ref(BlockDriverState *bs) 5932 { 5933 bs->refcnt++; 5934 } 5935 5936 /* Release a previously grabbed reference to bs. 5937 * If after releasing, reference count is zero, the BlockDriverState is 5938 * deleted. */ 5939 void bdrv_unref(BlockDriverState *bs) 5940 { 5941 if (!bs) { 5942 return; 5943 } 5944 assert(bs->refcnt > 0); 5945 if (--bs->refcnt == 0) { 5946 bdrv_delete(bs); 5947 } 5948 } 5949 5950 struct BdrvOpBlocker { 5951 Error *reason; 5952 QLIST_ENTRY(BdrvOpBlocker) list; 5953 }; 5954 5955 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp) 5956 { 5957 BdrvOpBlocker *blocker; 5958 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 5959 if (!QLIST_EMPTY(&bs->op_blockers[op])) { 5960 blocker = QLIST_FIRST(&bs->op_blockers[op]); 5961 error_propagate_prepend(errp, error_copy(blocker->reason), 5962 "Node '%s' is busy: ", 5963 bdrv_get_device_or_node_name(bs)); 5964 return true; 5965 } 5966 return false; 5967 } 5968 5969 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason) 5970 { 5971 BdrvOpBlocker *blocker; 5972 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 5973 5974 blocker = g_new0(BdrvOpBlocker, 1); 5975 blocker->reason = reason; 5976 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); 5977 } 5978 5979 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason) 5980 { 5981 BdrvOpBlocker *blocker, *next; 5982 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 5983 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) { 5984 if (blocker->reason == reason) { 5985 QLIST_REMOVE(blocker, list); 5986 g_free(blocker); 5987 } 5988 } 5989 } 5990 5991 void bdrv_op_block_all(BlockDriverState *bs, Error *reason) 5992 { 5993 int i; 5994 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 5995 bdrv_op_block(bs, i, reason); 5996 } 5997 } 5998 5999 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason) 6000 { 6001 int i; 6002 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 6003 bdrv_op_unblock(bs, i, reason); 6004 } 6005 } 6006 6007 bool bdrv_op_blocker_is_empty(BlockDriverState *bs) 6008 { 6009 int i; 6010 6011 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 6012 if (!QLIST_EMPTY(&bs->op_blockers[i])) { 6013 return false; 6014 } 6015 } 6016 return true; 6017 } 6018 6019 void bdrv_img_create(const char *filename, const char *fmt, 6020 const char *base_filename, const char *base_fmt, 6021 char *options, uint64_t img_size, int flags, bool quiet, 6022 Error **errp) 6023 { 6024 QemuOptsList *create_opts = NULL; 6025 QemuOpts *opts = NULL; 6026 const char *backing_fmt, *backing_file; 6027 int64_t size; 6028 BlockDriver *drv, *proto_drv; 6029 Error *local_err = NULL; 6030 int ret = 0; 6031 6032 /* Find driver and parse its options */ 6033 drv = bdrv_find_format(fmt); 6034 if (!drv) { 6035 error_setg(errp, "Unknown file format '%s'", fmt); 6036 return; 6037 } 6038 6039 proto_drv = bdrv_find_protocol(filename, true, errp); 6040 if (!proto_drv) { 6041 return; 6042 } 6043 6044 if (!drv->create_opts) { 6045 error_setg(errp, "Format driver '%s' does not support image creation", 6046 drv->format_name); 6047 return; 6048 } 6049 6050 if (!proto_drv->create_opts) { 6051 error_setg(errp, "Protocol driver '%s' does not support image creation", 6052 proto_drv->format_name); 6053 return; 6054 } 6055 6056 /* Create parameter list */ 6057 create_opts = qemu_opts_append(create_opts, drv->create_opts); 6058 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts); 6059 6060 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort); 6061 6062 /* Parse -o options */ 6063 if (options) { 6064 if (!qemu_opts_do_parse(opts, options, NULL, &local_err)) { 6065 goto out; 6066 } 6067 } 6068 6069 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) { 6070 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort); 6071 } else if (img_size != UINT64_C(-1)) { 6072 error_setg(errp, "The image size must be specified only once"); 6073 goto out; 6074 } 6075 6076 if (base_filename) { 6077 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename, 6078 NULL)) { 6079 error_setg(errp, "Backing file not supported for file format '%s'", 6080 fmt); 6081 goto out; 6082 } 6083 } 6084 6085 if (base_fmt) { 6086 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) { 6087 error_setg(errp, "Backing file format not supported for file " 6088 "format '%s'", fmt); 6089 goto out; 6090 } 6091 } 6092 6093 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE); 6094 if (backing_file) { 6095 if (!strcmp(filename, backing_file)) { 6096 error_setg(errp, "Error: Trying to create an image with the " 6097 "same filename as the backing file"); 6098 goto out; 6099 } 6100 } 6101 6102 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT); 6103 6104 /* The size for the image must always be specified, unless we have a backing 6105 * file and we have not been forbidden from opening it. */ 6106 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size); 6107 if (backing_file && !(flags & BDRV_O_NO_BACKING)) { 6108 BlockDriverState *bs; 6109 char *full_backing; 6110 int back_flags; 6111 QDict *backing_options = NULL; 6112 6113 full_backing = 6114 bdrv_get_full_backing_filename_from_filename(filename, backing_file, 6115 &local_err); 6116 if (local_err) { 6117 goto out; 6118 } 6119 assert(full_backing); 6120 6121 /* backing files always opened read-only */ 6122 back_flags = flags; 6123 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING); 6124 6125 backing_options = qdict_new(); 6126 if (backing_fmt) { 6127 qdict_put_str(backing_options, "driver", backing_fmt); 6128 } 6129 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true); 6130 6131 bs = bdrv_open(full_backing, NULL, backing_options, back_flags, 6132 &local_err); 6133 g_free(full_backing); 6134 if (!bs && size != -1) { 6135 /* Couldn't open BS, but we have a size, so it's nonfatal */ 6136 warn_reportf_err(local_err, 6137 "Could not verify backing image. " 6138 "This may become an error in future versions.\n"); 6139 local_err = NULL; 6140 } else if (!bs) { 6141 /* Couldn't open bs, do not have size */ 6142 error_append_hint(&local_err, 6143 "Could not open backing image to determine size.\n"); 6144 goto out; 6145 } else { 6146 if (size == -1) { 6147 /* Opened BS, have no size */ 6148 size = bdrv_getlength(bs); 6149 if (size < 0) { 6150 error_setg_errno(errp, -size, "Could not get size of '%s'", 6151 backing_file); 6152 bdrv_unref(bs); 6153 goto out; 6154 } 6155 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort); 6156 } 6157 bdrv_unref(bs); 6158 } 6159 } /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */ 6160 6161 if (size == -1) { 6162 error_setg(errp, "Image creation needs a size parameter"); 6163 goto out; 6164 } 6165 6166 if (!quiet) { 6167 printf("Formatting '%s', fmt=%s ", filename, fmt); 6168 qemu_opts_print(opts, " "); 6169 puts(""); 6170 } 6171 6172 ret = bdrv_create(drv, filename, opts, &local_err); 6173 6174 if (ret == -EFBIG) { 6175 /* This is generally a better message than whatever the driver would 6176 * deliver (especially because of the cluster_size_hint), since that 6177 * is most probably not much different from "image too large". */ 6178 const char *cluster_size_hint = ""; 6179 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) { 6180 cluster_size_hint = " (try using a larger cluster size)"; 6181 } 6182 error_setg(errp, "The image size is too large for file format '%s'" 6183 "%s", fmt, cluster_size_hint); 6184 error_free(local_err); 6185 local_err = NULL; 6186 } 6187 6188 out: 6189 qemu_opts_del(opts); 6190 qemu_opts_free(create_opts); 6191 error_propagate(errp, local_err); 6192 } 6193 6194 AioContext *bdrv_get_aio_context(BlockDriverState *bs) 6195 { 6196 return bs ? bs->aio_context : qemu_get_aio_context(); 6197 } 6198 6199 void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co) 6200 { 6201 aio_co_enter(bdrv_get_aio_context(bs), co); 6202 } 6203 6204 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban) 6205 { 6206 QLIST_REMOVE(ban, list); 6207 g_free(ban); 6208 } 6209 6210 static void bdrv_detach_aio_context(BlockDriverState *bs) 6211 { 6212 BdrvAioNotifier *baf, *baf_tmp; 6213 6214 assert(!bs->walking_aio_notifiers); 6215 bs->walking_aio_notifiers = true; 6216 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) { 6217 if (baf->deleted) { 6218 bdrv_do_remove_aio_context_notifier(baf); 6219 } else { 6220 baf->detach_aio_context(baf->opaque); 6221 } 6222 } 6223 /* Never mind iterating again to check for ->deleted. bdrv_close() will 6224 * remove remaining aio notifiers if we aren't called again. 6225 */ 6226 bs->walking_aio_notifiers = false; 6227 6228 if (bs->drv && bs->drv->bdrv_detach_aio_context) { 6229 bs->drv->bdrv_detach_aio_context(bs); 6230 } 6231 6232 if (bs->quiesce_counter) { 6233 aio_enable_external(bs->aio_context); 6234 } 6235 bs->aio_context = NULL; 6236 } 6237 6238 static void bdrv_attach_aio_context(BlockDriverState *bs, 6239 AioContext *new_context) 6240 { 6241 BdrvAioNotifier *ban, *ban_tmp; 6242 6243 if (bs->quiesce_counter) { 6244 aio_disable_external(new_context); 6245 } 6246 6247 bs->aio_context = new_context; 6248 6249 if (bs->drv && bs->drv->bdrv_attach_aio_context) { 6250 bs->drv->bdrv_attach_aio_context(bs, new_context); 6251 } 6252 6253 assert(!bs->walking_aio_notifiers); 6254 bs->walking_aio_notifiers = true; 6255 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) { 6256 if (ban->deleted) { 6257 bdrv_do_remove_aio_context_notifier(ban); 6258 } else { 6259 ban->attached_aio_context(new_context, ban->opaque); 6260 } 6261 } 6262 bs->walking_aio_notifiers = false; 6263 } 6264 6265 /* 6266 * Changes the AioContext used for fd handlers, timers, and BHs by this 6267 * BlockDriverState and all its children and parents. 6268 * 6269 * Must be called from the main AioContext. 6270 * 6271 * The caller must own the AioContext lock for the old AioContext of bs, but it 6272 * must not own the AioContext lock for new_context (unless new_context is the 6273 * same as the current context of bs). 6274 * 6275 * @ignore will accumulate all visited BdrvChild object. The caller is 6276 * responsible for freeing the list afterwards. 6277 */ 6278 void bdrv_set_aio_context_ignore(BlockDriverState *bs, 6279 AioContext *new_context, GSList **ignore) 6280 { 6281 AioContext *old_context = bdrv_get_aio_context(bs); 6282 BdrvChild *child; 6283 6284 g_assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 6285 6286 if (old_context == new_context) { 6287 return; 6288 } 6289 6290 bdrv_drained_begin(bs); 6291 6292 QLIST_FOREACH(child, &bs->children, next) { 6293 if (g_slist_find(*ignore, child)) { 6294 continue; 6295 } 6296 *ignore = g_slist_prepend(*ignore, child); 6297 bdrv_set_aio_context_ignore(child->bs, new_context, ignore); 6298 } 6299 QLIST_FOREACH(child, &bs->parents, next_parent) { 6300 if (g_slist_find(*ignore, child)) { 6301 continue; 6302 } 6303 assert(child->klass->set_aio_ctx); 6304 *ignore = g_slist_prepend(*ignore, child); 6305 child->klass->set_aio_ctx(child, new_context, ignore); 6306 } 6307 6308 bdrv_detach_aio_context(bs); 6309 6310 /* Acquire the new context, if necessary */ 6311 if (qemu_get_aio_context() != new_context) { 6312 aio_context_acquire(new_context); 6313 } 6314 6315 bdrv_attach_aio_context(bs, new_context); 6316 6317 /* 6318 * If this function was recursively called from 6319 * bdrv_set_aio_context_ignore(), there may be nodes in the 6320 * subtree that have not yet been moved to the new AioContext. 6321 * Release the old one so bdrv_drained_end() can poll them. 6322 */ 6323 if (qemu_get_aio_context() != old_context) { 6324 aio_context_release(old_context); 6325 } 6326 6327 bdrv_drained_end(bs); 6328 6329 if (qemu_get_aio_context() != old_context) { 6330 aio_context_acquire(old_context); 6331 } 6332 if (qemu_get_aio_context() != new_context) { 6333 aio_context_release(new_context); 6334 } 6335 } 6336 6337 static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx, 6338 GSList **ignore, Error **errp) 6339 { 6340 if (g_slist_find(*ignore, c)) { 6341 return true; 6342 } 6343 *ignore = g_slist_prepend(*ignore, c); 6344 6345 /* 6346 * A BdrvChildClass that doesn't handle AioContext changes cannot 6347 * tolerate any AioContext changes 6348 */ 6349 if (!c->klass->can_set_aio_ctx) { 6350 char *user = bdrv_child_user_desc(c); 6351 error_setg(errp, "Changing iothreads is not supported by %s", user); 6352 g_free(user); 6353 return false; 6354 } 6355 if (!c->klass->can_set_aio_ctx(c, ctx, ignore, errp)) { 6356 assert(!errp || *errp); 6357 return false; 6358 } 6359 return true; 6360 } 6361 6362 bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx, 6363 GSList **ignore, Error **errp) 6364 { 6365 if (g_slist_find(*ignore, c)) { 6366 return true; 6367 } 6368 *ignore = g_slist_prepend(*ignore, c); 6369 return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp); 6370 } 6371 6372 /* @ignore will accumulate all visited BdrvChild object. The caller is 6373 * responsible for freeing the list afterwards. */ 6374 bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx, 6375 GSList **ignore, Error **errp) 6376 { 6377 BdrvChild *c; 6378 6379 if (bdrv_get_aio_context(bs) == ctx) { 6380 return true; 6381 } 6382 6383 QLIST_FOREACH(c, &bs->parents, next_parent) { 6384 if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) { 6385 return false; 6386 } 6387 } 6388 QLIST_FOREACH(c, &bs->children, next) { 6389 if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) { 6390 return false; 6391 } 6392 } 6393 6394 return true; 6395 } 6396 6397 int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, 6398 BdrvChild *ignore_child, Error **errp) 6399 { 6400 GSList *ignore; 6401 bool ret; 6402 6403 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL; 6404 ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp); 6405 g_slist_free(ignore); 6406 6407 if (!ret) { 6408 return -EPERM; 6409 } 6410 6411 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL; 6412 bdrv_set_aio_context_ignore(bs, ctx, &ignore); 6413 g_slist_free(ignore); 6414 6415 return 0; 6416 } 6417 6418 int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, 6419 Error **errp) 6420 { 6421 return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp); 6422 } 6423 6424 void bdrv_add_aio_context_notifier(BlockDriverState *bs, 6425 void (*attached_aio_context)(AioContext *new_context, void *opaque), 6426 void (*detach_aio_context)(void *opaque), void *opaque) 6427 { 6428 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1); 6429 *ban = (BdrvAioNotifier){ 6430 .attached_aio_context = attached_aio_context, 6431 .detach_aio_context = detach_aio_context, 6432 .opaque = opaque 6433 }; 6434 6435 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list); 6436 } 6437 6438 void bdrv_remove_aio_context_notifier(BlockDriverState *bs, 6439 void (*attached_aio_context)(AioContext *, 6440 void *), 6441 void (*detach_aio_context)(void *), 6442 void *opaque) 6443 { 6444 BdrvAioNotifier *ban, *ban_next; 6445 6446 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 6447 if (ban->attached_aio_context == attached_aio_context && 6448 ban->detach_aio_context == detach_aio_context && 6449 ban->opaque == opaque && 6450 ban->deleted == false) 6451 { 6452 if (bs->walking_aio_notifiers) { 6453 ban->deleted = true; 6454 } else { 6455 bdrv_do_remove_aio_context_notifier(ban); 6456 } 6457 return; 6458 } 6459 } 6460 6461 abort(); 6462 } 6463 6464 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts, 6465 BlockDriverAmendStatusCB *status_cb, void *cb_opaque, 6466 bool force, 6467 Error **errp) 6468 { 6469 if (!bs->drv) { 6470 error_setg(errp, "Node is ejected"); 6471 return -ENOMEDIUM; 6472 } 6473 if (!bs->drv->bdrv_amend_options) { 6474 error_setg(errp, "Block driver '%s' does not support option amendment", 6475 bs->drv->format_name); 6476 return -ENOTSUP; 6477 } 6478 return bs->drv->bdrv_amend_options(bs, opts, status_cb, 6479 cb_opaque, force, errp); 6480 } 6481 6482 /* 6483 * This function checks whether the given @to_replace is allowed to be 6484 * replaced by a node that always shows the same data as @bs. This is 6485 * used for example to verify whether the mirror job can replace 6486 * @to_replace by the target mirrored from @bs. 6487 * To be replaceable, @bs and @to_replace may either be guaranteed to 6488 * always show the same data (because they are only connected through 6489 * filters), or some driver may allow replacing one of its children 6490 * because it can guarantee that this child's data is not visible at 6491 * all (for example, for dissenting quorum children that have no other 6492 * parents). 6493 */ 6494 bool bdrv_recurse_can_replace(BlockDriverState *bs, 6495 BlockDriverState *to_replace) 6496 { 6497 if (!bs || !bs->drv) { 6498 return false; 6499 } 6500 6501 if (bs == to_replace) { 6502 return true; 6503 } 6504 6505 /* See what the driver can do */ 6506 if (bs->drv->bdrv_recurse_can_replace) { 6507 return bs->drv->bdrv_recurse_can_replace(bs, to_replace); 6508 } 6509 6510 /* For filters without an own implementation, we can recurse on our own */ 6511 if (bs->drv->is_filter) { 6512 BdrvChild *child = bs->file ?: bs->backing; 6513 return bdrv_recurse_can_replace(child->bs, to_replace); 6514 } 6515 6516 /* Safe default */ 6517 return false; 6518 } 6519 6520 /* 6521 * Check whether the given @node_name can be replaced by a node that 6522 * has the same data as @parent_bs. If so, return @node_name's BDS; 6523 * NULL otherwise. 6524 * 6525 * @node_name must be a (recursive) *child of @parent_bs (or this 6526 * function will return NULL). 6527 * 6528 * The result (whether the node can be replaced or not) is only valid 6529 * for as long as no graph or permission changes occur. 6530 */ 6531 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs, 6532 const char *node_name, Error **errp) 6533 { 6534 BlockDriverState *to_replace_bs = bdrv_find_node(node_name); 6535 AioContext *aio_context; 6536 6537 if (!to_replace_bs) { 6538 error_setg(errp, "Node name '%s' not found", node_name); 6539 return NULL; 6540 } 6541 6542 aio_context = bdrv_get_aio_context(to_replace_bs); 6543 aio_context_acquire(aio_context); 6544 6545 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) { 6546 to_replace_bs = NULL; 6547 goto out; 6548 } 6549 6550 /* We don't want arbitrary node of the BDS chain to be replaced only the top 6551 * most non filter in order to prevent data corruption. 6552 * Another benefit is that this tests exclude backing files which are 6553 * blocked by the backing blockers. 6554 */ 6555 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) { 6556 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', " 6557 "because it cannot be guaranteed that doing so would not " 6558 "lead to an abrupt change of visible data", 6559 node_name, parent_bs->node_name); 6560 to_replace_bs = NULL; 6561 goto out; 6562 } 6563 6564 out: 6565 aio_context_release(aio_context); 6566 return to_replace_bs; 6567 } 6568 6569 /** 6570 * Iterates through the list of runtime option keys that are said to 6571 * be "strong" for a BDS. An option is called "strong" if it changes 6572 * a BDS's data. For example, the null block driver's "size" and 6573 * "read-zeroes" options are strong, but its "latency-ns" option is 6574 * not. 6575 * 6576 * If a key returned by this function ends with a dot, all options 6577 * starting with that prefix are strong. 6578 */ 6579 static const char *const *strong_options(BlockDriverState *bs, 6580 const char *const *curopt) 6581 { 6582 static const char *const global_options[] = { 6583 "driver", "filename", NULL 6584 }; 6585 6586 if (!curopt) { 6587 return &global_options[0]; 6588 } 6589 6590 curopt++; 6591 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) { 6592 curopt = bs->drv->strong_runtime_opts; 6593 } 6594 6595 return (curopt && *curopt) ? curopt : NULL; 6596 } 6597 6598 /** 6599 * Copies all strong runtime options from bs->options to the given 6600 * QDict. The set of strong option keys is determined by invoking 6601 * strong_options(). 6602 * 6603 * Returns true iff any strong option was present in bs->options (and 6604 * thus copied to the target QDict) with the exception of "filename" 6605 * and "driver". The caller is expected to use this value to decide 6606 * whether the existence of strong options prevents the generation of 6607 * a plain filename. 6608 */ 6609 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs) 6610 { 6611 bool found_any = false; 6612 const char *const *option_name = NULL; 6613 6614 if (!bs->drv) { 6615 return false; 6616 } 6617 6618 while ((option_name = strong_options(bs, option_name))) { 6619 bool option_given = false; 6620 6621 assert(strlen(*option_name) > 0); 6622 if ((*option_name)[strlen(*option_name) - 1] != '.') { 6623 QObject *entry = qdict_get(bs->options, *option_name); 6624 if (!entry) { 6625 continue; 6626 } 6627 6628 qdict_put_obj(d, *option_name, qobject_ref(entry)); 6629 option_given = true; 6630 } else { 6631 const QDictEntry *entry; 6632 for (entry = qdict_first(bs->options); entry; 6633 entry = qdict_next(bs->options, entry)) 6634 { 6635 if (strstart(qdict_entry_key(entry), *option_name, NULL)) { 6636 qdict_put_obj(d, qdict_entry_key(entry), 6637 qobject_ref(qdict_entry_value(entry))); 6638 option_given = true; 6639 } 6640 } 6641 } 6642 6643 /* While "driver" and "filename" need to be included in a JSON filename, 6644 * their existence does not prohibit generation of a plain filename. */ 6645 if (!found_any && option_given && 6646 strcmp(*option_name, "driver") && strcmp(*option_name, "filename")) 6647 { 6648 found_any = true; 6649 } 6650 } 6651 6652 if (!qdict_haskey(d, "driver")) { 6653 /* Drivers created with bdrv_new_open_driver() may not have a 6654 * @driver option. Add it here. */ 6655 qdict_put_str(d, "driver", bs->drv->format_name); 6656 } 6657 6658 return found_any; 6659 } 6660 6661 /* Note: This function may return false positives; it may return true 6662 * even if opening the backing file specified by bs's image header 6663 * would result in exactly bs->backing. */ 6664 static bool bdrv_backing_overridden(BlockDriverState *bs) 6665 { 6666 if (bs->backing) { 6667 return strcmp(bs->auto_backing_file, 6668 bs->backing->bs->filename); 6669 } else { 6670 /* No backing BDS, so if the image header reports any backing 6671 * file, it must have been suppressed */ 6672 return bs->auto_backing_file[0] != '\0'; 6673 } 6674 } 6675 6676 /* Updates the following BDS fields: 6677 * - exact_filename: A filename which may be used for opening a block device 6678 * which (mostly) equals the given BDS (even without any 6679 * other options; so reading and writing must return the same 6680 * results, but caching etc. may be different) 6681 * - full_open_options: Options which, when given when opening a block device 6682 * (without a filename), result in a BDS (mostly) 6683 * equalling the given one 6684 * - filename: If exact_filename is set, it is copied here. Otherwise, 6685 * full_open_options is converted to a JSON object, prefixed with 6686 * "json:" (for use through the JSON pseudo protocol) and put here. 6687 */ 6688 void bdrv_refresh_filename(BlockDriverState *bs) 6689 { 6690 BlockDriver *drv = bs->drv; 6691 BdrvChild *child; 6692 QDict *opts; 6693 bool backing_overridden; 6694 bool generate_json_filename; /* Whether our default implementation should 6695 fill exact_filename (false) or not (true) */ 6696 6697 if (!drv) { 6698 return; 6699 } 6700 6701 /* This BDS's file name may depend on any of its children's file names, so 6702 * refresh those first */ 6703 QLIST_FOREACH(child, &bs->children, next) { 6704 bdrv_refresh_filename(child->bs); 6705 } 6706 6707 if (bs->implicit) { 6708 /* For implicit nodes, just copy everything from the single child */ 6709 child = QLIST_FIRST(&bs->children); 6710 assert(QLIST_NEXT(child, next) == NULL); 6711 6712 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 6713 child->bs->exact_filename); 6714 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename); 6715 6716 qobject_unref(bs->full_open_options); 6717 bs->full_open_options = qobject_ref(child->bs->full_open_options); 6718 6719 return; 6720 } 6721 6722 backing_overridden = bdrv_backing_overridden(bs); 6723 6724 if (bs->open_flags & BDRV_O_NO_IO) { 6725 /* Without I/O, the backing file does not change anything. 6726 * Therefore, in such a case (primarily qemu-img), we can 6727 * pretend the backing file has not been overridden even if 6728 * it technically has been. */ 6729 backing_overridden = false; 6730 } 6731 6732 /* Gather the options QDict */ 6733 opts = qdict_new(); 6734 generate_json_filename = append_strong_runtime_options(opts, bs); 6735 generate_json_filename |= backing_overridden; 6736 6737 if (drv->bdrv_gather_child_options) { 6738 /* Some block drivers may not want to present all of their children's 6739 * options, or name them differently from BdrvChild.name */ 6740 drv->bdrv_gather_child_options(bs, opts, backing_overridden); 6741 } else { 6742 QLIST_FOREACH(child, &bs->children, next) { 6743 if (child == bs->backing && !backing_overridden) { 6744 /* We can skip the backing BDS if it has not been overridden */ 6745 continue; 6746 } 6747 6748 qdict_put(opts, child->name, 6749 qobject_ref(child->bs->full_open_options)); 6750 } 6751 6752 if (backing_overridden && !bs->backing) { 6753 /* Force no backing file */ 6754 qdict_put_null(opts, "backing"); 6755 } 6756 } 6757 6758 qobject_unref(bs->full_open_options); 6759 bs->full_open_options = opts; 6760 6761 if (drv->bdrv_refresh_filename) { 6762 /* Obsolete information is of no use here, so drop the old file name 6763 * information before refreshing it */ 6764 bs->exact_filename[0] = '\0'; 6765 6766 drv->bdrv_refresh_filename(bs); 6767 } else if (bs->file) { 6768 /* Try to reconstruct valid information from the underlying file */ 6769 6770 bs->exact_filename[0] = '\0'; 6771 6772 /* 6773 * We can use the underlying file's filename if: 6774 * - it has a filename, 6775 * - the file is a protocol BDS, and 6776 * - opening that file (as this BDS's format) will automatically create 6777 * the BDS tree we have right now, that is: 6778 * - the user did not significantly change this BDS's behavior with 6779 * some explicit (strong) options 6780 * - no non-file child of this BDS has been overridden by the user 6781 * Both of these conditions are represented by generate_json_filename. 6782 */ 6783 if (bs->file->bs->exact_filename[0] && 6784 bs->file->bs->drv->bdrv_file_open && 6785 !generate_json_filename) 6786 { 6787 strcpy(bs->exact_filename, bs->file->bs->exact_filename); 6788 } 6789 } 6790 6791 if (bs->exact_filename[0]) { 6792 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename); 6793 } else { 6794 QString *json = qobject_to_json(QOBJECT(bs->full_open_options)); 6795 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s", 6796 qstring_get_str(json)) >= sizeof(bs->filename)) { 6797 /* Give user a hint if we truncated things. */ 6798 strcpy(bs->filename + sizeof(bs->filename) - 4, "..."); 6799 } 6800 qobject_unref(json); 6801 } 6802 } 6803 6804 char *bdrv_dirname(BlockDriverState *bs, Error **errp) 6805 { 6806 BlockDriver *drv = bs->drv; 6807 6808 if (!drv) { 6809 error_setg(errp, "Node '%s' is ejected", bs->node_name); 6810 return NULL; 6811 } 6812 6813 if (drv->bdrv_dirname) { 6814 return drv->bdrv_dirname(bs, errp); 6815 } 6816 6817 if (bs->file) { 6818 return bdrv_dirname(bs->file->bs, errp); 6819 } 6820 6821 bdrv_refresh_filename(bs); 6822 if (bs->exact_filename[0] != '\0') { 6823 return path_combine(bs->exact_filename, ""); 6824 } 6825 6826 error_setg(errp, "Cannot generate a base directory for %s nodes", 6827 drv->format_name); 6828 return NULL; 6829 } 6830 6831 /* 6832 * Hot add/remove a BDS's child. So the user can take a child offline when 6833 * it is broken and take a new child online 6834 */ 6835 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, 6836 Error **errp) 6837 { 6838 6839 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) { 6840 error_setg(errp, "The node %s does not support adding a child", 6841 bdrv_get_device_or_node_name(parent_bs)); 6842 return; 6843 } 6844 6845 if (!QLIST_EMPTY(&child_bs->parents)) { 6846 error_setg(errp, "The node %s already has a parent", 6847 child_bs->node_name); 6848 return; 6849 } 6850 6851 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp); 6852 } 6853 6854 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) 6855 { 6856 BdrvChild *tmp; 6857 6858 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) { 6859 error_setg(errp, "The node %s does not support removing a child", 6860 bdrv_get_device_or_node_name(parent_bs)); 6861 return; 6862 } 6863 6864 QLIST_FOREACH(tmp, &parent_bs->children, next) { 6865 if (tmp == child) { 6866 break; 6867 } 6868 } 6869 6870 if (!tmp) { 6871 error_setg(errp, "The node %s does not have a child named %s", 6872 bdrv_get_device_or_node_name(parent_bs), 6873 bdrv_get_device_or_node_name(child->bs)); 6874 return; 6875 } 6876 6877 parent_bs->drv->bdrv_del_child(parent_bs, child, errp); 6878 } 6879 6880 int bdrv_make_empty(BdrvChild *c, Error **errp) 6881 { 6882 BlockDriver *drv = c->bs->drv; 6883 int ret; 6884 6885 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)); 6886 6887 if (!drv->bdrv_make_empty) { 6888 error_setg(errp, "%s does not support emptying nodes", 6889 drv->format_name); 6890 return -ENOTSUP; 6891 } 6892 6893 ret = drv->bdrv_make_empty(c->bs); 6894 if (ret < 0) { 6895 error_setg_errno(errp, -ret, "Failed to empty %s", 6896 c->bs->filename); 6897 return ret; 6898 } 6899 6900 return 0; 6901 } 6902