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/fuse.h" 30 #include "block/nbd.h" 31 #include "block/qdict.h" 32 #include "qemu/error-report.h" 33 #include "block/module_block.h" 34 #include "qemu/main-loop.h" 35 #include "qemu/module.h" 36 #include "qapi/error.h" 37 #include "qapi/qmp/qdict.h" 38 #include "qapi/qmp/qjson.h" 39 #include "qapi/qmp/qnull.h" 40 #include "qapi/qmp/qstring.h" 41 #include "qapi/qobject-output-visitor.h" 42 #include "qapi/qapi-visit-block-core.h" 43 #include "sysemu/block-backend.h" 44 #include "sysemu/sysemu.h" 45 #include "qemu/notify.h" 46 #include "qemu/option.h" 47 #include "qemu/coroutine.h" 48 #include "block/qapi.h" 49 #include "qemu/timer.h" 50 #include "qemu/cutils.h" 51 #include "qemu/id.h" 52 #include "block/coroutines.h" 53 54 #ifdef CONFIG_BSD 55 #include <sys/ioctl.h> 56 #include <sys/queue.h> 57 #ifndef __DragonFly__ 58 #include <sys/disk.h> 59 #endif 60 #endif 61 62 #ifdef _WIN32 63 #include <windows.h> 64 #endif 65 66 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */ 67 68 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states = 69 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states); 70 71 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states = 72 QTAILQ_HEAD_INITIALIZER(all_bdrv_states); 73 74 static QLIST_HEAD(, BlockDriver) bdrv_drivers = 75 QLIST_HEAD_INITIALIZER(bdrv_drivers); 76 77 static BlockDriverState *bdrv_open_inherit(const char *filename, 78 const char *reference, 79 QDict *options, int flags, 80 BlockDriverState *parent, 81 const BdrvChildClass *child_class, 82 BdrvChildRole child_role, 83 Error **errp); 84 85 /* If non-zero, use only whitelisted block drivers */ 86 static int use_bdrv_whitelist; 87 88 #ifdef _WIN32 89 static int is_windows_drive_prefix(const char *filename) 90 { 91 return (((filename[0] >= 'a' && filename[0] <= 'z') || 92 (filename[0] >= 'A' && filename[0] <= 'Z')) && 93 filename[1] == ':'); 94 } 95 96 int is_windows_drive(const char *filename) 97 { 98 if (is_windows_drive_prefix(filename) && 99 filename[2] == '\0') 100 return 1; 101 if (strstart(filename, "\\\\.\\", NULL) || 102 strstart(filename, "//./", NULL)) 103 return 1; 104 return 0; 105 } 106 #endif 107 108 size_t bdrv_opt_mem_align(BlockDriverState *bs) 109 { 110 if (!bs || !bs->drv) { 111 /* page size or 4k (hdd sector size) should be on the safe side */ 112 return MAX(4096, qemu_real_host_page_size); 113 } 114 115 return bs->bl.opt_mem_alignment; 116 } 117 118 size_t bdrv_min_mem_align(BlockDriverState *bs) 119 { 120 if (!bs || !bs->drv) { 121 /* page size or 4k (hdd sector size) should be on the safe side */ 122 return MAX(4096, qemu_real_host_page_size); 123 } 124 125 return bs->bl.min_mem_alignment; 126 } 127 128 /* check if the path starts with "<protocol>:" */ 129 int path_has_protocol(const char *path) 130 { 131 const char *p; 132 133 #ifdef _WIN32 134 if (is_windows_drive(path) || 135 is_windows_drive_prefix(path)) { 136 return 0; 137 } 138 p = path + strcspn(path, ":/\\"); 139 #else 140 p = path + strcspn(path, ":/"); 141 #endif 142 143 return *p == ':'; 144 } 145 146 int path_is_absolute(const char *path) 147 { 148 #ifdef _WIN32 149 /* specific case for names like: "\\.\d:" */ 150 if (is_windows_drive(path) || is_windows_drive_prefix(path)) { 151 return 1; 152 } 153 return (*path == '/' || *path == '\\'); 154 #else 155 return (*path == '/'); 156 #endif 157 } 158 159 /* if filename is absolute, just return its duplicate. Otherwise, build a 160 path to it by considering it is relative to base_path. URL are 161 supported. */ 162 char *path_combine(const char *base_path, const char *filename) 163 { 164 const char *protocol_stripped = NULL; 165 const char *p, *p1; 166 char *result; 167 int len; 168 169 if (path_is_absolute(filename)) { 170 return g_strdup(filename); 171 } 172 173 if (path_has_protocol(base_path)) { 174 protocol_stripped = strchr(base_path, ':'); 175 if (protocol_stripped) { 176 protocol_stripped++; 177 } 178 } 179 p = protocol_stripped ?: base_path; 180 181 p1 = strrchr(base_path, '/'); 182 #ifdef _WIN32 183 { 184 const char *p2; 185 p2 = strrchr(base_path, '\\'); 186 if (!p1 || p2 > p1) { 187 p1 = p2; 188 } 189 } 190 #endif 191 if (p1) { 192 p1++; 193 } else { 194 p1 = base_path; 195 } 196 if (p1 > p) { 197 p = p1; 198 } 199 len = p - base_path; 200 201 result = g_malloc(len + strlen(filename) + 1); 202 memcpy(result, base_path, len); 203 strcpy(result + len, filename); 204 205 return result; 206 } 207 208 /* 209 * Helper function for bdrv_parse_filename() implementations to remove optional 210 * protocol prefixes (especially "file:") from a filename and for putting the 211 * stripped filename into the options QDict if there is such a prefix. 212 */ 213 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, 214 QDict *options) 215 { 216 if (strstart(filename, prefix, &filename)) { 217 /* Stripping the explicit protocol prefix may result in a protocol 218 * prefix being (wrongly) detected (if the filename contains a colon) */ 219 if (path_has_protocol(filename)) { 220 GString *fat_filename; 221 222 /* This means there is some colon before the first slash; therefore, 223 * this cannot be an absolute path */ 224 assert(!path_is_absolute(filename)); 225 226 /* And we can thus fix the protocol detection issue by prefixing it 227 * by "./" */ 228 fat_filename = g_string_new("./"); 229 g_string_append(fat_filename, filename); 230 231 assert(!path_has_protocol(fat_filename->str)); 232 233 qdict_put(options, "filename", 234 qstring_from_gstring(fat_filename)); 235 } else { 236 /* If no protocol prefix was detected, we can use the shortened 237 * filename as-is */ 238 qdict_put_str(options, "filename", filename); 239 } 240 } 241 } 242 243 244 /* Returns whether the image file is opened as read-only. Note that this can 245 * return false and writing to the image file is still not possible because the 246 * image is inactivated. */ 247 bool bdrv_is_read_only(BlockDriverState *bs) 248 { 249 return bs->read_only; 250 } 251 252 int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, 253 bool ignore_allow_rdw, Error **errp) 254 { 255 /* Do not set read_only if copy_on_read is enabled */ 256 if (bs->copy_on_read && read_only) { 257 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled", 258 bdrv_get_device_or_node_name(bs)); 259 return -EINVAL; 260 } 261 262 /* Do not clear read_only if it is prohibited */ 263 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) && 264 !ignore_allow_rdw) 265 { 266 error_setg(errp, "Node '%s' is read only", 267 bdrv_get_device_or_node_name(bs)); 268 return -EPERM; 269 } 270 271 return 0; 272 } 273 274 /* 275 * Called by a driver that can only provide a read-only image. 276 * 277 * Returns 0 if the node is already read-only or it could switch the node to 278 * read-only because BDRV_O_AUTO_RDONLY is set. 279 * 280 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set 281 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg 282 * is not NULL, it is used as the error message for the Error object. 283 */ 284 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg, 285 Error **errp) 286 { 287 int ret = 0; 288 289 if (!(bs->open_flags & BDRV_O_RDWR)) { 290 return 0; 291 } 292 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) { 293 goto fail; 294 } 295 296 ret = bdrv_can_set_read_only(bs, true, false, NULL); 297 if (ret < 0) { 298 goto fail; 299 } 300 301 bs->read_only = true; 302 bs->open_flags &= ~BDRV_O_RDWR; 303 304 return 0; 305 306 fail: 307 error_setg(errp, "%s", errmsg ?: "Image is read-only"); 308 return -EACCES; 309 } 310 311 /* 312 * If @backing is empty, this function returns NULL without setting 313 * @errp. In all other cases, NULL will only be returned with @errp 314 * set. 315 * 316 * Therefore, a return value of NULL without @errp set means that 317 * there is no backing file; if @errp is set, there is one but its 318 * absolute filename cannot be generated. 319 */ 320 char *bdrv_get_full_backing_filename_from_filename(const char *backed, 321 const char *backing, 322 Error **errp) 323 { 324 if (backing[0] == '\0') { 325 return NULL; 326 } else if (path_has_protocol(backing) || path_is_absolute(backing)) { 327 return g_strdup(backing); 328 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) { 329 error_setg(errp, "Cannot use relative backing file names for '%s'", 330 backed); 331 return NULL; 332 } else { 333 return path_combine(backed, backing); 334 } 335 } 336 337 /* 338 * If @filename is empty or NULL, this function returns NULL without 339 * setting @errp. In all other cases, NULL will only be returned with 340 * @errp set. 341 */ 342 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to, 343 const char *filename, Error **errp) 344 { 345 char *dir, *full_name; 346 347 if (!filename || filename[0] == '\0') { 348 return NULL; 349 } else if (path_has_protocol(filename) || path_is_absolute(filename)) { 350 return g_strdup(filename); 351 } 352 353 dir = bdrv_dirname(relative_to, errp); 354 if (!dir) { 355 return NULL; 356 } 357 358 full_name = g_strconcat(dir, filename, NULL); 359 g_free(dir); 360 return full_name; 361 } 362 363 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp) 364 { 365 return bdrv_make_absolute_filename(bs, bs->backing_file, errp); 366 } 367 368 void bdrv_register(BlockDriver *bdrv) 369 { 370 assert(bdrv->format_name); 371 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list); 372 } 373 374 BlockDriverState *bdrv_new(void) 375 { 376 BlockDriverState *bs; 377 int i; 378 379 bs = g_new0(BlockDriverState, 1); 380 QLIST_INIT(&bs->dirty_bitmaps); 381 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 382 QLIST_INIT(&bs->op_blockers[i]); 383 } 384 notifier_with_return_list_init(&bs->before_write_notifiers); 385 qemu_co_mutex_init(&bs->reqs_lock); 386 qemu_mutex_init(&bs->dirty_bitmap_mutex); 387 bs->refcnt = 1; 388 bs->aio_context = qemu_get_aio_context(); 389 390 qemu_co_queue_init(&bs->flush_queue); 391 392 for (i = 0; i < bdrv_drain_all_count; i++) { 393 bdrv_drained_begin(bs); 394 } 395 396 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list); 397 398 return bs; 399 } 400 401 static BlockDriver *bdrv_do_find_format(const char *format_name) 402 { 403 BlockDriver *drv1; 404 405 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 406 if (!strcmp(drv1->format_name, format_name)) { 407 return drv1; 408 } 409 } 410 411 return NULL; 412 } 413 414 BlockDriver *bdrv_find_format(const char *format_name) 415 { 416 BlockDriver *drv1; 417 int i; 418 419 drv1 = bdrv_do_find_format(format_name); 420 if (drv1) { 421 return drv1; 422 } 423 424 /* The driver isn't registered, maybe we need to load a module */ 425 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 426 if (!strcmp(block_driver_modules[i].format_name, format_name)) { 427 block_module_load_one(block_driver_modules[i].library_name); 428 break; 429 } 430 } 431 432 return bdrv_do_find_format(format_name); 433 } 434 435 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only) 436 { 437 static const char *whitelist_rw[] = { 438 CONFIG_BDRV_RW_WHITELIST 439 NULL 440 }; 441 static const char *whitelist_ro[] = { 442 CONFIG_BDRV_RO_WHITELIST 443 NULL 444 }; 445 const char **p; 446 447 if (!whitelist_rw[0] && !whitelist_ro[0]) { 448 return 1; /* no whitelist, anything goes */ 449 } 450 451 for (p = whitelist_rw; *p; p++) { 452 if (!strcmp(format_name, *p)) { 453 return 1; 454 } 455 } 456 if (read_only) { 457 for (p = whitelist_ro; *p; p++) { 458 if (!strcmp(format_name, *p)) { 459 return 1; 460 } 461 } 462 } 463 return 0; 464 } 465 466 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only) 467 { 468 return bdrv_format_is_whitelisted(drv->format_name, read_only); 469 } 470 471 bool bdrv_uses_whitelist(void) 472 { 473 return use_bdrv_whitelist; 474 } 475 476 typedef struct CreateCo { 477 BlockDriver *drv; 478 char *filename; 479 QemuOpts *opts; 480 int ret; 481 Error *err; 482 } CreateCo; 483 484 static void coroutine_fn bdrv_create_co_entry(void *opaque) 485 { 486 Error *local_err = NULL; 487 int ret; 488 489 CreateCo *cco = opaque; 490 assert(cco->drv); 491 492 ret = cco->drv->bdrv_co_create_opts(cco->drv, 493 cco->filename, cco->opts, &local_err); 494 error_propagate(&cco->err, local_err); 495 cco->ret = ret; 496 } 497 498 int bdrv_create(BlockDriver *drv, const char* filename, 499 QemuOpts *opts, Error **errp) 500 { 501 int ret; 502 503 Coroutine *co; 504 CreateCo cco = { 505 .drv = drv, 506 .filename = g_strdup(filename), 507 .opts = opts, 508 .ret = NOT_DONE, 509 .err = NULL, 510 }; 511 512 if (!drv->bdrv_co_create_opts) { 513 error_setg(errp, "Driver '%s' does not support image creation", drv->format_name); 514 ret = -ENOTSUP; 515 goto out; 516 } 517 518 if (qemu_in_coroutine()) { 519 /* Fast-path if already in coroutine context */ 520 bdrv_create_co_entry(&cco); 521 } else { 522 co = qemu_coroutine_create(bdrv_create_co_entry, &cco); 523 qemu_coroutine_enter(co); 524 while (cco.ret == NOT_DONE) { 525 aio_poll(qemu_get_aio_context(), true); 526 } 527 } 528 529 ret = cco.ret; 530 if (ret < 0) { 531 if (cco.err) { 532 error_propagate(errp, cco.err); 533 } else { 534 error_setg_errno(errp, -ret, "Could not create image"); 535 } 536 } 537 538 out: 539 g_free(cco.filename); 540 return ret; 541 } 542 543 /** 544 * Helper function for bdrv_create_file_fallback(): Resize @blk to at 545 * least the given @minimum_size. 546 * 547 * On success, return @blk's actual length. 548 * Otherwise, return -errno. 549 */ 550 static int64_t create_file_fallback_truncate(BlockBackend *blk, 551 int64_t minimum_size, Error **errp) 552 { 553 Error *local_err = NULL; 554 int64_t size; 555 int ret; 556 557 ret = blk_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0, 558 &local_err); 559 if (ret < 0 && ret != -ENOTSUP) { 560 error_propagate(errp, local_err); 561 return ret; 562 } 563 564 size = blk_getlength(blk); 565 if (size < 0) { 566 error_free(local_err); 567 error_setg_errno(errp, -size, 568 "Failed to inquire the new image file's length"); 569 return size; 570 } 571 572 if (size < minimum_size) { 573 /* Need to grow the image, but we failed to do that */ 574 error_propagate(errp, local_err); 575 return -ENOTSUP; 576 } 577 578 error_free(local_err); 579 local_err = NULL; 580 581 return size; 582 } 583 584 /** 585 * Helper function for bdrv_create_file_fallback(): Zero the first 586 * sector to remove any potentially pre-existing image header. 587 */ 588 static int create_file_fallback_zero_first_sector(BlockBackend *blk, 589 int64_t current_size, 590 Error **errp) 591 { 592 int64_t bytes_to_clear; 593 int ret; 594 595 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE); 596 if (bytes_to_clear) { 597 ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP); 598 if (ret < 0) { 599 error_setg_errno(errp, -ret, 600 "Failed to clear the new image's first sector"); 601 return ret; 602 } 603 } 604 605 return 0; 606 } 607 608 /** 609 * Simple implementation of bdrv_co_create_opts for protocol drivers 610 * which only support creation via opening a file 611 * (usually existing raw storage device) 612 */ 613 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv, 614 const char *filename, 615 QemuOpts *opts, 616 Error **errp) 617 { 618 BlockBackend *blk; 619 QDict *options; 620 int64_t size = 0; 621 char *buf = NULL; 622 PreallocMode prealloc; 623 Error *local_err = NULL; 624 int ret; 625 626 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0); 627 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC); 628 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf, 629 PREALLOC_MODE_OFF, &local_err); 630 g_free(buf); 631 if (local_err) { 632 error_propagate(errp, local_err); 633 return -EINVAL; 634 } 635 636 if (prealloc != PREALLOC_MODE_OFF) { 637 error_setg(errp, "Unsupported preallocation mode '%s'", 638 PreallocMode_str(prealloc)); 639 return -ENOTSUP; 640 } 641 642 options = qdict_new(); 643 qdict_put_str(options, "driver", drv->format_name); 644 645 blk = blk_new_open(filename, NULL, options, 646 BDRV_O_RDWR | BDRV_O_RESIZE, errp); 647 if (!blk) { 648 error_prepend(errp, "Protocol driver '%s' does not support image " 649 "creation, and opening the image failed: ", 650 drv->format_name); 651 return -EINVAL; 652 } 653 654 size = create_file_fallback_truncate(blk, size, errp); 655 if (size < 0) { 656 ret = size; 657 goto out; 658 } 659 660 ret = create_file_fallback_zero_first_sector(blk, size, errp); 661 if (ret < 0) { 662 goto out; 663 } 664 665 ret = 0; 666 out: 667 blk_unref(blk); 668 return ret; 669 } 670 671 int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp) 672 { 673 BlockDriver *drv; 674 675 drv = bdrv_find_protocol(filename, true, errp); 676 if (drv == NULL) { 677 return -ENOENT; 678 } 679 680 return bdrv_create(drv, filename, opts, errp); 681 } 682 683 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp) 684 { 685 Error *local_err = NULL; 686 int ret; 687 688 assert(bs != NULL); 689 690 if (!bs->drv) { 691 error_setg(errp, "Block node '%s' is not opened", bs->filename); 692 return -ENOMEDIUM; 693 } 694 695 if (!bs->drv->bdrv_co_delete_file) { 696 error_setg(errp, "Driver '%s' does not support image deletion", 697 bs->drv->format_name); 698 return -ENOTSUP; 699 } 700 701 ret = bs->drv->bdrv_co_delete_file(bs, &local_err); 702 if (ret < 0) { 703 error_propagate(errp, local_err); 704 } 705 706 return ret; 707 } 708 709 /** 710 * Try to get @bs's logical and physical block size. 711 * On success, store them in @bsz struct and return 0. 712 * On failure return -errno. 713 * @bs must not be empty. 714 */ 715 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz) 716 { 717 BlockDriver *drv = bs->drv; 718 BlockDriverState *filtered = bdrv_filter_bs(bs); 719 720 if (drv && drv->bdrv_probe_blocksizes) { 721 return drv->bdrv_probe_blocksizes(bs, bsz); 722 } else if (filtered) { 723 return bdrv_probe_blocksizes(filtered, bsz); 724 } 725 726 return -ENOTSUP; 727 } 728 729 /** 730 * Try to get @bs's geometry (cyls, heads, sectors). 731 * On success, store them in @geo struct and return 0. 732 * On failure return -errno. 733 * @bs must not be empty. 734 */ 735 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo) 736 { 737 BlockDriver *drv = bs->drv; 738 BlockDriverState *filtered = bdrv_filter_bs(bs); 739 740 if (drv && drv->bdrv_probe_geometry) { 741 return drv->bdrv_probe_geometry(bs, geo); 742 } else if (filtered) { 743 return bdrv_probe_geometry(filtered, geo); 744 } 745 746 return -ENOTSUP; 747 } 748 749 /* 750 * Create a uniquely-named empty temporary file. 751 * Return 0 upon success, otherwise a negative errno value. 752 */ 753 int get_tmp_filename(char *filename, int size) 754 { 755 #ifdef _WIN32 756 char temp_dir[MAX_PATH]; 757 /* GetTempFileName requires that its output buffer (4th param) 758 have length MAX_PATH or greater. */ 759 assert(size >= MAX_PATH); 760 return (GetTempPath(MAX_PATH, temp_dir) 761 && GetTempFileName(temp_dir, "qem", 0, filename) 762 ? 0 : -GetLastError()); 763 #else 764 int fd; 765 const char *tmpdir; 766 tmpdir = getenv("TMPDIR"); 767 if (!tmpdir) { 768 tmpdir = "/var/tmp"; 769 } 770 if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) { 771 return -EOVERFLOW; 772 } 773 fd = mkstemp(filename); 774 if (fd < 0) { 775 return -errno; 776 } 777 if (close(fd) != 0) { 778 unlink(filename); 779 return -errno; 780 } 781 return 0; 782 #endif 783 } 784 785 /* 786 * Detect host devices. By convention, /dev/cdrom[N] is always 787 * recognized as a host CDROM. 788 */ 789 static BlockDriver *find_hdev_driver(const char *filename) 790 { 791 int score_max = 0, score; 792 BlockDriver *drv = NULL, *d; 793 794 QLIST_FOREACH(d, &bdrv_drivers, list) { 795 if (d->bdrv_probe_device) { 796 score = d->bdrv_probe_device(filename); 797 if (score > score_max) { 798 score_max = score; 799 drv = d; 800 } 801 } 802 } 803 804 return drv; 805 } 806 807 static BlockDriver *bdrv_do_find_protocol(const char *protocol) 808 { 809 BlockDriver *drv1; 810 811 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 812 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) { 813 return drv1; 814 } 815 } 816 817 return NULL; 818 } 819 820 BlockDriver *bdrv_find_protocol(const char *filename, 821 bool allow_protocol_prefix, 822 Error **errp) 823 { 824 BlockDriver *drv1; 825 char protocol[128]; 826 int len; 827 const char *p; 828 int i; 829 830 /* TODO Drivers without bdrv_file_open must be specified explicitly */ 831 832 /* 833 * XXX(hch): we really should not let host device detection 834 * override an explicit protocol specification, but moving this 835 * later breaks access to device names with colons in them. 836 * Thanks to the brain-dead persistent naming schemes on udev- 837 * based Linux systems those actually are quite common. 838 */ 839 drv1 = find_hdev_driver(filename); 840 if (drv1) { 841 return drv1; 842 } 843 844 if (!path_has_protocol(filename) || !allow_protocol_prefix) { 845 return &bdrv_file; 846 } 847 848 p = strchr(filename, ':'); 849 assert(p != NULL); 850 len = p - filename; 851 if (len > sizeof(protocol) - 1) 852 len = sizeof(protocol) - 1; 853 memcpy(protocol, filename, len); 854 protocol[len] = '\0'; 855 856 drv1 = bdrv_do_find_protocol(protocol); 857 if (drv1) { 858 return drv1; 859 } 860 861 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 862 if (block_driver_modules[i].protocol_name && 863 !strcmp(block_driver_modules[i].protocol_name, protocol)) { 864 block_module_load_one(block_driver_modules[i].library_name); 865 break; 866 } 867 } 868 869 drv1 = bdrv_do_find_protocol(protocol); 870 if (!drv1) { 871 error_setg(errp, "Unknown protocol '%s'", protocol); 872 } 873 return drv1; 874 } 875 876 /* 877 * Guess image format by probing its contents. 878 * This is not a good idea when your image is raw (CVE-2008-2004), but 879 * we do it anyway for backward compatibility. 880 * 881 * @buf contains the image's first @buf_size bytes. 882 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE, 883 * but can be smaller if the image file is smaller) 884 * @filename is its filename. 885 * 886 * For all block drivers, call the bdrv_probe() method to get its 887 * probing score. 888 * Return the first block driver with the highest probing score. 889 */ 890 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size, 891 const char *filename) 892 { 893 int score_max = 0, score; 894 BlockDriver *drv = NULL, *d; 895 896 QLIST_FOREACH(d, &bdrv_drivers, list) { 897 if (d->bdrv_probe) { 898 score = d->bdrv_probe(buf, buf_size, filename); 899 if (score > score_max) { 900 score_max = score; 901 drv = d; 902 } 903 } 904 } 905 906 return drv; 907 } 908 909 static int find_image_format(BlockBackend *file, const char *filename, 910 BlockDriver **pdrv, Error **errp) 911 { 912 BlockDriver *drv; 913 uint8_t buf[BLOCK_PROBE_BUF_SIZE]; 914 int ret = 0; 915 916 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */ 917 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) { 918 *pdrv = &bdrv_raw; 919 return ret; 920 } 921 922 ret = blk_pread(file, 0, buf, sizeof(buf)); 923 if (ret < 0) { 924 error_setg_errno(errp, -ret, "Could not read image for determining its " 925 "format"); 926 *pdrv = NULL; 927 return ret; 928 } 929 930 drv = bdrv_probe_all(buf, ret, filename); 931 if (!drv) { 932 error_setg(errp, "Could not determine image format: No compatible " 933 "driver found"); 934 ret = -ENOENT; 935 } 936 *pdrv = drv; 937 return ret; 938 } 939 940 /** 941 * Set the current 'total_sectors' value 942 * Return 0 on success, -errno on error. 943 */ 944 int refresh_total_sectors(BlockDriverState *bs, int64_t hint) 945 { 946 BlockDriver *drv = bs->drv; 947 948 if (!drv) { 949 return -ENOMEDIUM; 950 } 951 952 /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */ 953 if (bdrv_is_sg(bs)) 954 return 0; 955 956 /* query actual device if possible, otherwise just trust the hint */ 957 if (drv->bdrv_getlength) { 958 int64_t length = drv->bdrv_getlength(bs); 959 if (length < 0) { 960 return length; 961 } 962 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE); 963 } 964 965 bs->total_sectors = hint; 966 967 if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) { 968 return -EFBIG; 969 } 970 971 return 0; 972 } 973 974 /** 975 * Combines a QDict of new block driver @options with any missing options taken 976 * from @old_options, so that leaving out an option defaults to its old value. 977 */ 978 static void bdrv_join_options(BlockDriverState *bs, QDict *options, 979 QDict *old_options) 980 { 981 if (bs->drv && bs->drv->bdrv_join_options) { 982 bs->drv->bdrv_join_options(options, old_options); 983 } else { 984 qdict_join(options, old_options, false); 985 } 986 } 987 988 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts, 989 int open_flags, 990 Error **errp) 991 { 992 Error *local_err = NULL; 993 char *value = qemu_opt_get_del(opts, "detect-zeroes"); 994 BlockdevDetectZeroesOptions detect_zeroes = 995 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value, 996 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err); 997 g_free(value); 998 if (local_err) { 999 error_propagate(errp, local_err); 1000 return detect_zeroes; 1001 } 1002 1003 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP && 1004 !(open_flags & BDRV_O_UNMAP)) 1005 { 1006 error_setg(errp, "setting detect-zeroes to unmap is not allowed " 1007 "without setting discard operation to unmap"); 1008 } 1009 1010 return detect_zeroes; 1011 } 1012 1013 /** 1014 * Set open flags for aio engine 1015 * 1016 * Return 0 on success, -1 if the engine specified is invalid 1017 */ 1018 int bdrv_parse_aio(const char *mode, int *flags) 1019 { 1020 if (!strcmp(mode, "threads")) { 1021 /* do nothing, default */ 1022 } else if (!strcmp(mode, "native")) { 1023 *flags |= BDRV_O_NATIVE_AIO; 1024 #ifdef CONFIG_LINUX_IO_URING 1025 } else if (!strcmp(mode, "io_uring")) { 1026 *flags |= BDRV_O_IO_URING; 1027 #endif 1028 } else { 1029 return -1; 1030 } 1031 1032 return 0; 1033 } 1034 1035 /** 1036 * Set open flags for a given discard mode 1037 * 1038 * Return 0 on success, -1 if the discard mode was invalid. 1039 */ 1040 int bdrv_parse_discard_flags(const char *mode, int *flags) 1041 { 1042 *flags &= ~BDRV_O_UNMAP; 1043 1044 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) { 1045 /* do nothing */ 1046 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) { 1047 *flags |= BDRV_O_UNMAP; 1048 } else { 1049 return -1; 1050 } 1051 1052 return 0; 1053 } 1054 1055 /** 1056 * Set open flags for a given cache mode 1057 * 1058 * Return 0 on success, -1 if the cache mode was invalid. 1059 */ 1060 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough) 1061 { 1062 *flags &= ~BDRV_O_CACHE_MASK; 1063 1064 if (!strcmp(mode, "off") || !strcmp(mode, "none")) { 1065 *writethrough = false; 1066 *flags |= BDRV_O_NOCACHE; 1067 } else if (!strcmp(mode, "directsync")) { 1068 *writethrough = true; 1069 *flags |= BDRV_O_NOCACHE; 1070 } else if (!strcmp(mode, "writeback")) { 1071 *writethrough = false; 1072 } else if (!strcmp(mode, "unsafe")) { 1073 *writethrough = false; 1074 *flags |= BDRV_O_NO_FLUSH; 1075 } else if (!strcmp(mode, "writethrough")) { 1076 *writethrough = true; 1077 } else { 1078 return -1; 1079 } 1080 1081 return 0; 1082 } 1083 1084 static char *bdrv_child_get_parent_desc(BdrvChild *c) 1085 { 1086 BlockDriverState *parent = c->opaque; 1087 return g_strdup(bdrv_get_device_or_node_name(parent)); 1088 } 1089 1090 static void bdrv_child_cb_drained_begin(BdrvChild *child) 1091 { 1092 BlockDriverState *bs = child->opaque; 1093 bdrv_do_drained_begin_quiesce(bs, NULL, false); 1094 } 1095 1096 static bool bdrv_child_cb_drained_poll(BdrvChild *child) 1097 { 1098 BlockDriverState *bs = child->opaque; 1099 return bdrv_drain_poll(bs, false, NULL, false); 1100 } 1101 1102 static void bdrv_child_cb_drained_end(BdrvChild *child, 1103 int *drained_end_counter) 1104 { 1105 BlockDriverState *bs = child->opaque; 1106 bdrv_drained_end_no_poll(bs, drained_end_counter); 1107 } 1108 1109 static int bdrv_child_cb_inactivate(BdrvChild *child) 1110 { 1111 BlockDriverState *bs = child->opaque; 1112 assert(bs->open_flags & BDRV_O_INACTIVE); 1113 return 0; 1114 } 1115 1116 static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx, 1117 GSList **ignore, Error **errp) 1118 { 1119 BlockDriverState *bs = child->opaque; 1120 return bdrv_can_set_aio_context(bs, ctx, ignore, errp); 1121 } 1122 1123 static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx, 1124 GSList **ignore) 1125 { 1126 BlockDriverState *bs = child->opaque; 1127 return bdrv_set_aio_context_ignore(bs, ctx, ignore); 1128 } 1129 1130 /* 1131 * Returns the options and flags that a temporary snapshot should get, based on 1132 * the originally requested flags (the originally requested image will have 1133 * flags like a backing file) 1134 */ 1135 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options, 1136 int parent_flags, QDict *parent_options) 1137 { 1138 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY; 1139 1140 /* For temporary files, unconditional cache=unsafe is fine */ 1141 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off"); 1142 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on"); 1143 1144 /* Copy the read-only and discard options from the parent */ 1145 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1146 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD); 1147 1148 /* aio=native doesn't work for cache.direct=off, so disable it for the 1149 * temporary snapshot */ 1150 *child_flags &= ~BDRV_O_NATIVE_AIO; 1151 } 1152 1153 static void bdrv_backing_attach(BdrvChild *c) 1154 { 1155 BlockDriverState *parent = c->opaque; 1156 BlockDriverState *backing_hd = c->bs; 1157 1158 assert(!parent->backing_blocker); 1159 error_setg(&parent->backing_blocker, 1160 "node is used as backing hd of '%s'", 1161 bdrv_get_device_or_node_name(parent)); 1162 1163 bdrv_refresh_filename(backing_hd); 1164 1165 parent->open_flags &= ~BDRV_O_NO_BACKING; 1166 1167 bdrv_op_block_all(backing_hd, parent->backing_blocker); 1168 /* Otherwise we won't be able to commit or stream */ 1169 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET, 1170 parent->backing_blocker); 1171 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM, 1172 parent->backing_blocker); 1173 /* 1174 * We do backup in 3 ways: 1175 * 1. drive backup 1176 * The target bs is new opened, and the source is top BDS 1177 * 2. blockdev backup 1178 * Both the source and the target are top BDSes. 1179 * 3. internal backup(used for block replication) 1180 * Both the source and the target are backing file 1181 * 1182 * In case 1 and 2, neither the source nor the target is the backing file. 1183 * In case 3, we will block the top BDS, so there is only one block job 1184 * for the top BDS and its backing chain. 1185 */ 1186 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE, 1187 parent->backing_blocker); 1188 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET, 1189 parent->backing_blocker); 1190 } 1191 1192 static void bdrv_backing_detach(BdrvChild *c) 1193 { 1194 BlockDriverState *parent = c->opaque; 1195 1196 assert(parent->backing_blocker); 1197 bdrv_op_unblock_all(c->bs, parent->backing_blocker); 1198 error_free(parent->backing_blocker); 1199 parent->backing_blocker = NULL; 1200 } 1201 1202 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base, 1203 const char *filename, Error **errp) 1204 { 1205 BlockDriverState *parent = c->opaque; 1206 bool read_only = bdrv_is_read_only(parent); 1207 int ret; 1208 1209 if (read_only) { 1210 ret = bdrv_reopen_set_read_only(parent, false, errp); 1211 if (ret < 0) { 1212 return ret; 1213 } 1214 } 1215 1216 ret = bdrv_change_backing_file(parent, filename, 1217 base->drv ? base->drv->format_name : "", 1218 false); 1219 if (ret < 0) { 1220 error_setg_errno(errp, -ret, "Could not update backing file link"); 1221 } 1222 1223 if (read_only) { 1224 bdrv_reopen_set_read_only(parent, true, NULL); 1225 } 1226 1227 return ret; 1228 } 1229 1230 /* 1231 * Returns the options and flags that a generic child of a BDS should 1232 * get, based on the given options and flags for the parent BDS. 1233 */ 1234 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format, 1235 int *child_flags, QDict *child_options, 1236 int parent_flags, QDict *parent_options) 1237 { 1238 int flags = parent_flags; 1239 1240 /* 1241 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL. 1242 * Generally, the question to answer is: Should this child be 1243 * format-probed by default? 1244 */ 1245 1246 /* 1247 * Pure and non-filtered data children of non-format nodes should 1248 * be probed by default (even when the node itself has BDRV_O_PROTOCOL 1249 * set). This only affects a very limited set of drivers (namely 1250 * quorum and blkverify when this comment was written). 1251 * Force-clear BDRV_O_PROTOCOL then. 1252 */ 1253 if (!parent_is_format && 1254 (role & BDRV_CHILD_DATA) && 1255 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED))) 1256 { 1257 flags &= ~BDRV_O_PROTOCOL; 1258 } 1259 1260 /* 1261 * All children of format nodes (except for COW children) and all 1262 * metadata children in general should never be format-probed. 1263 * Force-set BDRV_O_PROTOCOL then. 1264 */ 1265 if ((parent_is_format && !(role & BDRV_CHILD_COW)) || 1266 (role & BDRV_CHILD_METADATA)) 1267 { 1268 flags |= BDRV_O_PROTOCOL; 1269 } 1270 1271 /* 1272 * If the cache mode isn't explicitly set, inherit direct and no-flush from 1273 * the parent. 1274 */ 1275 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT); 1276 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH); 1277 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE); 1278 1279 if (role & BDRV_CHILD_COW) { 1280 /* backing files are opened read-only by default */ 1281 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on"); 1282 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off"); 1283 } else { 1284 /* Inherit the read-only option from the parent if it's not set */ 1285 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1286 qdict_copy_default(child_options, parent_options, 1287 BDRV_OPT_AUTO_READ_ONLY); 1288 } 1289 1290 /* 1291 * bdrv_co_pdiscard() respects unmap policy for the parent, so we 1292 * can default to enable it on lower layers regardless of the 1293 * parent option. 1294 */ 1295 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap"); 1296 1297 /* Clear flags that only apply to the top layer */ 1298 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ); 1299 1300 if (role & BDRV_CHILD_METADATA) { 1301 flags &= ~BDRV_O_NO_IO; 1302 } 1303 if (role & BDRV_CHILD_COW) { 1304 flags &= ~BDRV_O_TEMPORARY; 1305 } 1306 1307 *child_flags = flags; 1308 } 1309 1310 static void bdrv_child_cb_attach(BdrvChild *child) 1311 { 1312 BlockDriverState *bs = child->opaque; 1313 1314 if (child->role & BDRV_CHILD_COW) { 1315 bdrv_backing_attach(child); 1316 } 1317 1318 bdrv_apply_subtree_drain(child, bs); 1319 } 1320 1321 static void bdrv_child_cb_detach(BdrvChild *child) 1322 { 1323 BlockDriverState *bs = child->opaque; 1324 1325 if (child->role & BDRV_CHILD_COW) { 1326 bdrv_backing_detach(child); 1327 } 1328 1329 bdrv_unapply_subtree_drain(child, bs); 1330 } 1331 1332 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base, 1333 const char *filename, Error **errp) 1334 { 1335 if (c->role & BDRV_CHILD_COW) { 1336 return bdrv_backing_update_filename(c, base, filename, errp); 1337 } 1338 return 0; 1339 } 1340 1341 const BdrvChildClass child_of_bds = { 1342 .parent_is_bds = true, 1343 .get_parent_desc = bdrv_child_get_parent_desc, 1344 .inherit_options = bdrv_inherited_options, 1345 .drained_begin = bdrv_child_cb_drained_begin, 1346 .drained_poll = bdrv_child_cb_drained_poll, 1347 .drained_end = bdrv_child_cb_drained_end, 1348 .attach = bdrv_child_cb_attach, 1349 .detach = bdrv_child_cb_detach, 1350 .inactivate = bdrv_child_cb_inactivate, 1351 .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx, 1352 .set_aio_ctx = bdrv_child_cb_set_aio_ctx, 1353 .update_filename = bdrv_child_cb_update_filename, 1354 }; 1355 1356 static int bdrv_open_flags(BlockDriverState *bs, int flags) 1357 { 1358 int open_flags = flags; 1359 1360 /* 1361 * Clear flags that are internal to the block layer before opening the 1362 * image. 1363 */ 1364 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL); 1365 1366 return open_flags; 1367 } 1368 1369 static void update_flags_from_options(int *flags, QemuOpts *opts) 1370 { 1371 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY); 1372 1373 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) { 1374 *flags |= BDRV_O_NO_FLUSH; 1375 } 1376 1377 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) { 1378 *flags |= BDRV_O_NOCACHE; 1379 } 1380 1381 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) { 1382 *flags |= BDRV_O_RDWR; 1383 } 1384 1385 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) { 1386 *flags |= BDRV_O_AUTO_RDONLY; 1387 } 1388 } 1389 1390 static void update_options_from_flags(QDict *options, int flags) 1391 { 1392 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) { 1393 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE); 1394 } 1395 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) { 1396 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH, 1397 flags & BDRV_O_NO_FLUSH); 1398 } 1399 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) { 1400 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR)); 1401 } 1402 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) { 1403 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY, 1404 flags & BDRV_O_AUTO_RDONLY); 1405 } 1406 } 1407 1408 static void bdrv_assign_node_name(BlockDriverState *bs, 1409 const char *node_name, 1410 Error **errp) 1411 { 1412 char *gen_node_name = NULL; 1413 1414 if (!node_name) { 1415 node_name = gen_node_name = id_generate(ID_BLOCK); 1416 } else if (!id_wellformed(node_name)) { 1417 /* 1418 * Check for empty string or invalid characters, but not if it is 1419 * generated (generated names use characters not available to the user) 1420 */ 1421 error_setg(errp, "Invalid node name"); 1422 return; 1423 } 1424 1425 /* takes care of avoiding namespaces collisions */ 1426 if (blk_by_name(node_name)) { 1427 error_setg(errp, "node-name=%s is conflicting with a device id", 1428 node_name); 1429 goto out; 1430 } 1431 1432 /* takes care of avoiding duplicates node names */ 1433 if (bdrv_find_node(node_name)) { 1434 error_setg(errp, "Duplicate node name"); 1435 goto out; 1436 } 1437 1438 /* Make sure that the node name isn't truncated */ 1439 if (strlen(node_name) >= sizeof(bs->node_name)) { 1440 error_setg(errp, "Node name too long"); 1441 goto out; 1442 } 1443 1444 /* copy node name into the bs and insert it into the graph list */ 1445 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name); 1446 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list); 1447 out: 1448 g_free(gen_node_name); 1449 } 1450 1451 static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, 1452 const char *node_name, QDict *options, 1453 int open_flags, Error **errp) 1454 { 1455 Error *local_err = NULL; 1456 int i, ret; 1457 1458 bdrv_assign_node_name(bs, node_name, &local_err); 1459 if (local_err) { 1460 error_propagate(errp, local_err); 1461 return -EINVAL; 1462 } 1463 1464 bs->drv = drv; 1465 bs->read_only = !(bs->open_flags & BDRV_O_RDWR); 1466 bs->opaque = g_malloc0(drv->instance_size); 1467 1468 if (drv->bdrv_file_open) { 1469 assert(!drv->bdrv_needs_filename || bs->filename[0]); 1470 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err); 1471 } else if (drv->bdrv_open) { 1472 ret = drv->bdrv_open(bs, options, open_flags, &local_err); 1473 } else { 1474 ret = 0; 1475 } 1476 1477 if (ret < 0) { 1478 if (local_err) { 1479 error_propagate(errp, local_err); 1480 } else if (bs->filename[0]) { 1481 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename); 1482 } else { 1483 error_setg_errno(errp, -ret, "Could not open image"); 1484 } 1485 goto open_failed; 1486 } 1487 1488 ret = refresh_total_sectors(bs, bs->total_sectors); 1489 if (ret < 0) { 1490 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 1491 return ret; 1492 } 1493 1494 bdrv_refresh_limits(bs, &local_err); 1495 if (local_err) { 1496 error_propagate(errp, local_err); 1497 return -EINVAL; 1498 } 1499 1500 assert(bdrv_opt_mem_align(bs) != 0); 1501 assert(bdrv_min_mem_align(bs) != 0); 1502 assert(is_power_of_2(bs->bl.request_alignment)); 1503 1504 for (i = 0; i < bs->quiesce_counter; i++) { 1505 if (drv->bdrv_co_drain_begin) { 1506 drv->bdrv_co_drain_begin(bs); 1507 } 1508 } 1509 1510 return 0; 1511 open_failed: 1512 bs->drv = NULL; 1513 if (bs->file != NULL) { 1514 bdrv_unref_child(bs, bs->file); 1515 bs->file = NULL; 1516 } 1517 g_free(bs->opaque); 1518 bs->opaque = NULL; 1519 return ret; 1520 } 1521 1522 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name, 1523 int flags, Error **errp) 1524 { 1525 BlockDriverState *bs; 1526 int ret; 1527 1528 bs = bdrv_new(); 1529 bs->open_flags = flags; 1530 bs->explicit_options = qdict_new(); 1531 bs->options = qdict_new(); 1532 bs->opaque = NULL; 1533 1534 update_options_from_flags(bs->options, flags); 1535 1536 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp); 1537 if (ret < 0) { 1538 qobject_unref(bs->explicit_options); 1539 bs->explicit_options = NULL; 1540 qobject_unref(bs->options); 1541 bs->options = NULL; 1542 bdrv_unref(bs); 1543 return NULL; 1544 } 1545 1546 return bs; 1547 } 1548 1549 QemuOptsList bdrv_runtime_opts = { 1550 .name = "bdrv_common", 1551 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head), 1552 .desc = { 1553 { 1554 .name = "node-name", 1555 .type = QEMU_OPT_STRING, 1556 .help = "Node name of the block device node", 1557 }, 1558 { 1559 .name = "driver", 1560 .type = QEMU_OPT_STRING, 1561 .help = "Block driver to use for the node", 1562 }, 1563 { 1564 .name = BDRV_OPT_CACHE_DIRECT, 1565 .type = QEMU_OPT_BOOL, 1566 .help = "Bypass software writeback cache on the host", 1567 }, 1568 { 1569 .name = BDRV_OPT_CACHE_NO_FLUSH, 1570 .type = QEMU_OPT_BOOL, 1571 .help = "Ignore flush requests", 1572 }, 1573 { 1574 .name = BDRV_OPT_READ_ONLY, 1575 .type = QEMU_OPT_BOOL, 1576 .help = "Node is opened in read-only mode", 1577 }, 1578 { 1579 .name = BDRV_OPT_AUTO_READ_ONLY, 1580 .type = QEMU_OPT_BOOL, 1581 .help = "Node can become read-only if opening read-write fails", 1582 }, 1583 { 1584 .name = "detect-zeroes", 1585 .type = QEMU_OPT_STRING, 1586 .help = "try to optimize zero writes (off, on, unmap)", 1587 }, 1588 { 1589 .name = BDRV_OPT_DISCARD, 1590 .type = QEMU_OPT_STRING, 1591 .help = "discard operation (ignore/off, unmap/on)", 1592 }, 1593 { 1594 .name = BDRV_OPT_FORCE_SHARE, 1595 .type = QEMU_OPT_BOOL, 1596 .help = "always accept other writers (default: off)", 1597 }, 1598 { /* end of list */ } 1599 }, 1600 }; 1601 1602 QemuOptsList bdrv_create_opts_simple = { 1603 .name = "simple-create-opts", 1604 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head), 1605 .desc = { 1606 { 1607 .name = BLOCK_OPT_SIZE, 1608 .type = QEMU_OPT_SIZE, 1609 .help = "Virtual disk size" 1610 }, 1611 { 1612 .name = BLOCK_OPT_PREALLOC, 1613 .type = QEMU_OPT_STRING, 1614 .help = "Preallocation mode (allowed values: off)" 1615 }, 1616 { /* end of list */ } 1617 } 1618 }; 1619 1620 /* 1621 * Common part for opening disk images and files 1622 * 1623 * Removes all processed options from *options. 1624 */ 1625 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file, 1626 QDict *options, Error **errp) 1627 { 1628 int ret, open_flags; 1629 const char *filename; 1630 const char *driver_name = NULL; 1631 const char *node_name = NULL; 1632 const char *discard; 1633 QemuOpts *opts; 1634 BlockDriver *drv; 1635 Error *local_err = NULL; 1636 1637 assert(bs->file == NULL); 1638 assert(options != NULL && bs->options != options); 1639 1640 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 1641 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 1642 ret = -EINVAL; 1643 goto fail_opts; 1644 } 1645 1646 update_flags_from_options(&bs->open_flags, opts); 1647 1648 driver_name = qemu_opt_get(opts, "driver"); 1649 drv = bdrv_find_format(driver_name); 1650 assert(drv != NULL); 1651 1652 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false); 1653 1654 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) { 1655 error_setg(errp, 1656 BDRV_OPT_FORCE_SHARE 1657 "=on can only be used with read-only images"); 1658 ret = -EINVAL; 1659 goto fail_opts; 1660 } 1661 1662 if (file != NULL) { 1663 bdrv_refresh_filename(blk_bs(file)); 1664 filename = blk_bs(file)->filename; 1665 } else { 1666 /* 1667 * Caution: while qdict_get_try_str() is fine, getting 1668 * non-string types would require more care. When @options 1669 * come from -blockdev or blockdev_add, its members are typed 1670 * according to the QAPI schema, but when they come from 1671 * -drive, they're all QString. 1672 */ 1673 filename = qdict_get_try_str(options, "filename"); 1674 } 1675 1676 if (drv->bdrv_needs_filename && (!filename || !filename[0])) { 1677 error_setg(errp, "The '%s' block driver requires a file name", 1678 drv->format_name); 1679 ret = -EINVAL; 1680 goto fail_opts; 1681 } 1682 1683 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags, 1684 drv->format_name); 1685 1686 bs->read_only = !(bs->open_flags & BDRV_O_RDWR); 1687 1688 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) { 1689 if (!bs->read_only && bdrv_is_whitelisted(drv, true)) { 1690 ret = bdrv_apply_auto_read_only(bs, NULL, NULL); 1691 } else { 1692 ret = -ENOTSUP; 1693 } 1694 if (ret < 0) { 1695 error_setg(errp, 1696 !bs->read_only && bdrv_is_whitelisted(drv, true) 1697 ? "Driver '%s' can only be used for read-only devices" 1698 : "Driver '%s' is not whitelisted", 1699 drv->format_name); 1700 goto fail_opts; 1701 } 1702 } 1703 1704 /* bdrv_new() and bdrv_close() make it so */ 1705 assert(qatomic_read(&bs->copy_on_read) == 0); 1706 1707 if (bs->open_flags & BDRV_O_COPY_ON_READ) { 1708 if (!bs->read_only) { 1709 bdrv_enable_copy_on_read(bs); 1710 } else { 1711 error_setg(errp, "Can't use copy-on-read on read-only device"); 1712 ret = -EINVAL; 1713 goto fail_opts; 1714 } 1715 } 1716 1717 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD); 1718 if (discard != NULL) { 1719 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) { 1720 error_setg(errp, "Invalid discard option"); 1721 ret = -EINVAL; 1722 goto fail_opts; 1723 } 1724 } 1725 1726 bs->detect_zeroes = 1727 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err); 1728 if (local_err) { 1729 error_propagate(errp, local_err); 1730 ret = -EINVAL; 1731 goto fail_opts; 1732 } 1733 1734 if (filename != NULL) { 1735 pstrcpy(bs->filename, sizeof(bs->filename), filename); 1736 } else { 1737 bs->filename[0] = '\0'; 1738 } 1739 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename); 1740 1741 /* Open the image, either directly or using a protocol */ 1742 open_flags = bdrv_open_flags(bs, bs->open_flags); 1743 node_name = qemu_opt_get(opts, "node-name"); 1744 1745 assert(!drv->bdrv_file_open || file == NULL); 1746 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp); 1747 if (ret < 0) { 1748 goto fail_opts; 1749 } 1750 1751 qemu_opts_del(opts); 1752 return 0; 1753 1754 fail_opts: 1755 qemu_opts_del(opts); 1756 return ret; 1757 } 1758 1759 static QDict *parse_json_filename(const char *filename, Error **errp) 1760 { 1761 QObject *options_obj; 1762 QDict *options; 1763 int ret; 1764 1765 ret = strstart(filename, "json:", &filename); 1766 assert(ret); 1767 1768 options_obj = qobject_from_json(filename, errp); 1769 if (!options_obj) { 1770 error_prepend(errp, "Could not parse the JSON options: "); 1771 return NULL; 1772 } 1773 1774 options = qobject_to(QDict, options_obj); 1775 if (!options) { 1776 qobject_unref(options_obj); 1777 error_setg(errp, "Invalid JSON object given"); 1778 return NULL; 1779 } 1780 1781 qdict_flatten(options); 1782 1783 return options; 1784 } 1785 1786 static void parse_json_protocol(QDict *options, const char **pfilename, 1787 Error **errp) 1788 { 1789 QDict *json_options; 1790 Error *local_err = NULL; 1791 1792 /* Parse json: pseudo-protocol */ 1793 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) { 1794 return; 1795 } 1796 1797 json_options = parse_json_filename(*pfilename, &local_err); 1798 if (local_err) { 1799 error_propagate(errp, local_err); 1800 return; 1801 } 1802 1803 /* Options given in the filename have lower priority than options 1804 * specified directly */ 1805 qdict_join(options, json_options, false); 1806 qobject_unref(json_options); 1807 *pfilename = NULL; 1808 } 1809 1810 /* 1811 * Fills in default options for opening images and converts the legacy 1812 * filename/flags pair to option QDict entries. 1813 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a 1814 * block driver has been specified explicitly. 1815 */ 1816 static int bdrv_fill_options(QDict **options, const char *filename, 1817 int *flags, Error **errp) 1818 { 1819 const char *drvname; 1820 bool protocol = *flags & BDRV_O_PROTOCOL; 1821 bool parse_filename = false; 1822 BlockDriver *drv = NULL; 1823 Error *local_err = NULL; 1824 1825 /* 1826 * Caution: while qdict_get_try_str() is fine, getting non-string 1827 * types would require more care. When @options come from 1828 * -blockdev or blockdev_add, its members are typed according to 1829 * the QAPI schema, but when they come from -drive, they're all 1830 * QString. 1831 */ 1832 drvname = qdict_get_try_str(*options, "driver"); 1833 if (drvname) { 1834 drv = bdrv_find_format(drvname); 1835 if (!drv) { 1836 error_setg(errp, "Unknown driver '%s'", drvname); 1837 return -ENOENT; 1838 } 1839 /* If the user has explicitly specified the driver, this choice should 1840 * override the BDRV_O_PROTOCOL flag */ 1841 protocol = drv->bdrv_file_open; 1842 } 1843 1844 if (protocol) { 1845 *flags |= BDRV_O_PROTOCOL; 1846 } else { 1847 *flags &= ~BDRV_O_PROTOCOL; 1848 } 1849 1850 /* Translate cache options from flags into options */ 1851 update_options_from_flags(*options, *flags); 1852 1853 /* Fetch the file name from the options QDict if necessary */ 1854 if (protocol && filename) { 1855 if (!qdict_haskey(*options, "filename")) { 1856 qdict_put_str(*options, "filename", filename); 1857 parse_filename = true; 1858 } else { 1859 error_setg(errp, "Can't specify 'file' and 'filename' options at " 1860 "the same time"); 1861 return -EINVAL; 1862 } 1863 } 1864 1865 /* Find the right block driver */ 1866 /* See cautionary note on accessing @options above */ 1867 filename = qdict_get_try_str(*options, "filename"); 1868 1869 if (!drvname && protocol) { 1870 if (filename) { 1871 drv = bdrv_find_protocol(filename, parse_filename, errp); 1872 if (!drv) { 1873 return -EINVAL; 1874 } 1875 1876 drvname = drv->format_name; 1877 qdict_put_str(*options, "driver", drvname); 1878 } else { 1879 error_setg(errp, "Must specify either driver or file"); 1880 return -EINVAL; 1881 } 1882 } 1883 1884 assert(drv || !protocol); 1885 1886 /* Driver-specific filename parsing */ 1887 if (drv && drv->bdrv_parse_filename && parse_filename) { 1888 drv->bdrv_parse_filename(filename, *options, &local_err); 1889 if (local_err) { 1890 error_propagate(errp, local_err); 1891 return -EINVAL; 1892 } 1893 1894 if (!drv->bdrv_needs_filename) { 1895 qdict_del(*options, "filename"); 1896 } 1897 } 1898 1899 return 0; 1900 } 1901 1902 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, 1903 uint64_t perm, uint64_t shared, 1904 GSList *ignore_children, Error **errp); 1905 static void bdrv_child_abort_perm_update(BdrvChild *c); 1906 static void bdrv_child_set_perm(BdrvChild *c); 1907 1908 typedef struct BlockReopenQueueEntry { 1909 bool prepared; 1910 bool perms_checked; 1911 BDRVReopenState state; 1912 QTAILQ_ENTRY(BlockReopenQueueEntry) entry; 1913 } BlockReopenQueueEntry; 1914 1915 /* 1916 * Return the flags that @bs will have after the reopens in @q have 1917 * successfully completed. If @q is NULL (or @bs is not contained in @q), 1918 * return the current flags. 1919 */ 1920 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs) 1921 { 1922 BlockReopenQueueEntry *entry; 1923 1924 if (q != NULL) { 1925 QTAILQ_FOREACH(entry, q, entry) { 1926 if (entry->state.bs == bs) { 1927 return entry->state.flags; 1928 } 1929 } 1930 } 1931 1932 return bs->open_flags; 1933 } 1934 1935 /* Returns whether the image file can be written to after the reopen queue @q 1936 * has been successfully applied, or right now if @q is NULL. */ 1937 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs, 1938 BlockReopenQueue *q) 1939 { 1940 int flags = bdrv_reopen_get_flags(q, bs); 1941 1942 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR; 1943 } 1944 1945 /* 1946 * Return whether the BDS can be written to. This is not necessarily 1947 * the same as !bdrv_is_read_only(bs), as inactivated images may not 1948 * be written to but do not count as read-only images. 1949 */ 1950 bool bdrv_is_writable(BlockDriverState *bs) 1951 { 1952 return bdrv_is_writable_after_reopen(bs, NULL); 1953 } 1954 1955 static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs, 1956 BdrvChild *c, BdrvChildRole role, 1957 BlockReopenQueue *reopen_queue, 1958 uint64_t parent_perm, uint64_t parent_shared, 1959 uint64_t *nperm, uint64_t *nshared) 1960 { 1961 assert(bs->drv && bs->drv->bdrv_child_perm); 1962 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue, 1963 parent_perm, parent_shared, 1964 nperm, nshared); 1965 /* TODO Take force_share from reopen_queue */ 1966 if (child_bs && child_bs->force_share) { 1967 *nshared = BLK_PERM_ALL; 1968 } 1969 } 1970 1971 /* 1972 * Check whether permissions on this node can be changed in a way that 1973 * @cumulative_perms and @cumulative_shared_perms are the new cumulative 1974 * permissions of all its parents. This involves checking whether all necessary 1975 * permission changes to child nodes can be performed. 1976 * 1977 * A call to this function must always be followed by a call to bdrv_set_perm() 1978 * or bdrv_abort_perm_update(). 1979 */ 1980 static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q, 1981 uint64_t cumulative_perms, 1982 uint64_t cumulative_shared_perms, 1983 GSList *ignore_children, Error **errp) 1984 { 1985 BlockDriver *drv = bs->drv; 1986 BdrvChild *c; 1987 int ret; 1988 1989 /* Write permissions never work with read-only images */ 1990 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && 1991 !bdrv_is_writable_after_reopen(bs, q)) 1992 { 1993 if (!bdrv_is_writable_after_reopen(bs, NULL)) { 1994 error_setg(errp, "Block node is read-only"); 1995 } else { 1996 uint64_t current_perms, current_shared; 1997 bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared); 1998 if (current_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) { 1999 error_setg(errp, "Cannot make block node read-only, there is " 2000 "a writer on it"); 2001 } else { 2002 error_setg(errp, "Cannot make block node read-only and create " 2003 "a writer on it"); 2004 } 2005 } 2006 2007 return -EPERM; 2008 } 2009 2010 /* 2011 * Unaligned requests will automatically be aligned to bl.request_alignment 2012 * and without RESIZE we can't extend requests to write to space beyond the 2013 * end of the image, so it's required that the image size is aligned. 2014 */ 2015 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && 2016 !(cumulative_perms & BLK_PERM_RESIZE)) 2017 { 2018 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) { 2019 error_setg(errp, "Cannot get 'write' permission without 'resize': " 2020 "Image size is not a multiple of request " 2021 "alignment"); 2022 return -EPERM; 2023 } 2024 } 2025 2026 /* Check this node */ 2027 if (!drv) { 2028 return 0; 2029 } 2030 2031 if (drv->bdrv_check_perm) { 2032 ret = drv->bdrv_check_perm(bs, cumulative_perms, 2033 cumulative_shared_perms, errp); 2034 if (ret < 0) { 2035 return ret; 2036 } 2037 } 2038 2039 /* Drivers that never have children can omit .bdrv_child_perm() */ 2040 if (!drv->bdrv_child_perm) { 2041 assert(QLIST_EMPTY(&bs->children)); 2042 return 0; 2043 } 2044 2045 /* Check all children */ 2046 QLIST_FOREACH(c, &bs->children, next) { 2047 uint64_t cur_perm, cur_shared; 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 errp); 2054 if (ret < 0) { 2055 return ret; 2056 } 2057 } 2058 2059 return 0; 2060 } 2061 2062 /* 2063 * Notifies drivers that after a previous bdrv_check_perm() call, the 2064 * permission update is not performed and any preparations made for it (e.g. 2065 * taken file locks) need to be undone. 2066 * 2067 * This function recursively notifies all child nodes. 2068 */ 2069 static void bdrv_abort_perm_update(BlockDriverState *bs) 2070 { 2071 BlockDriver *drv = bs->drv; 2072 BdrvChild *c; 2073 2074 if (!drv) { 2075 return; 2076 } 2077 2078 if (drv->bdrv_abort_perm_update) { 2079 drv->bdrv_abort_perm_update(bs); 2080 } 2081 2082 QLIST_FOREACH(c, &bs->children, next) { 2083 bdrv_child_abort_perm_update(c); 2084 } 2085 } 2086 2087 static void bdrv_set_perm(BlockDriverState *bs) 2088 { 2089 uint64_t cumulative_perms, cumulative_shared_perms; 2090 BlockDriver *drv = bs->drv; 2091 BdrvChild *c; 2092 2093 if (!drv) { 2094 return; 2095 } 2096 2097 bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms); 2098 2099 /* Update this node */ 2100 if (drv->bdrv_set_perm) { 2101 drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms); 2102 } 2103 2104 /* Drivers that never have children can omit .bdrv_child_perm() */ 2105 if (!drv->bdrv_child_perm) { 2106 assert(QLIST_EMPTY(&bs->children)); 2107 return; 2108 } 2109 2110 /* Update all children */ 2111 QLIST_FOREACH(c, &bs->children, next) { 2112 bdrv_child_set_perm(c); 2113 } 2114 } 2115 2116 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm, 2117 uint64_t *shared_perm) 2118 { 2119 BdrvChild *c; 2120 uint64_t cumulative_perms = 0; 2121 uint64_t cumulative_shared_perms = BLK_PERM_ALL; 2122 2123 QLIST_FOREACH(c, &bs->parents, next_parent) { 2124 cumulative_perms |= c->perm; 2125 cumulative_shared_perms &= c->shared_perm; 2126 } 2127 2128 *perm = cumulative_perms; 2129 *shared_perm = cumulative_shared_perms; 2130 } 2131 2132 static char *bdrv_child_user_desc(BdrvChild *c) 2133 { 2134 if (c->klass->get_parent_desc) { 2135 return c->klass->get_parent_desc(c); 2136 } 2137 2138 return g_strdup("another user"); 2139 } 2140 2141 char *bdrv_perm_names(uint64_t perm) 2142 { 2143 struct perm_name { 2144 uint64_t perm; 2145 const char *name; 2146 } permissions[] = { 2147 { BLK_PERM_CONSISTENT_READ, "consistent read" }, 2148 { BLK_PERM_WRITE, "write" }, 2149 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" }, 2150 { BLK_PERM_RESIZE, "resize" }, 2151 { BLK_PERM_GRAPH_MOD, "change children" }, 2152 { 0, NULL } 2153 }; 2154 2155 GString *result = g_string_sized_new(30); 2156 struct perm_name *p; 2157 2158 for (p = permissions; p->name; p++) { 2159 if (perm & p->perm) { 2160 if (result->len > 0) { 2161 g_string_append(result, ", "); 2162 } 2163 g_string_append(result, p->name); 2164 } 2165 } 2166 2167 return g_string_free(result, FALSE); 2168 } 2169 2170 /* 2171 * Checks whether a new reference to @bs can be added if the new user requires 2172 * @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is 2173 * set, the BdrvChild objects in this list are ignored in the calculations; 2174 * this allows checking permission updates for an existing reference. 2175 * 2176 * Needs to be followed by a call to either bdrv_set_perm() or 2177 * bdrv_abort_perm_update(). */ 2178 static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q, 2179 uint64_t new_used_perm, 2180 uint64_t new_shared_perm, 2181 GSList *ignore_children, 2182 Error **errp) 2183 { 2184 BdrvChild *c; 2185 uint64_t cumulative_perms = new_used_perm; 2186 uint64_t cumulative_shared_perms = new_shared_perm; 2187 2188 2189 /* There is no reason why anyone couldn't tolerate write_unchanged */ 2190 assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED); 2191 2192 QLIST_FOREACH(c, &bs->parents, next_parent) { 2193 if (g_slist_find(ignore_children, c)) { 2194 continue; 2195 } 2196 2197 if ((new_used_perm & c->shared_perm) != new_used_perm) { 2198 char *user = bdrv_child_user_desc(c); 2199 char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm); 2200 2201 error_setg(errp, "Conflicts with use by %s as '%s', which does not " 2202 "allow '%s' on %s", 2203 user, c->name, perm_names, bdrv_get_node_name(c->bs)); 2204 g_free(user); 2205 g_free(perm_names); 2206 return -EPERM; 2207 } 2208 2209 if ((c->perm & new_shared_perm) != c->perm) { 2210 char *user = bdrv_child_user_desc(c); 2211 char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm); 2212 2213 error_setg(errp, "Conflicts with use by %s as '%s', which uses " 2214 "'%s' on %s", 2215 user, c->name, perm_names, bdrv_get_node_name(c->bs)); 2216 g_free(user); 2217 g_free(perm_names); 2218 return -EPERM; 2219 } 2220 2221 cumulative_perms |= c->perm; 2222 cumulative_shared_perms &= c->shared_perm; 2223 } 2224 2225 return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms, 2226 ignore_children, errp); 2227 } 2228 2229 /* Needs to be followed by a call to either bdrv_child_set_perm() or 2230 * bdrv_child_abort_perm_update(). */ 2231 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q, 2232 uint64_t perm, uint64_t shared, 2233 GSList *ignore_children, Error **errp) 2234 { 2235 int ret; 2236 2237 ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c); 2238 ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children, errp); 2239 g_slist_free(ignore_children); 2240 2241 if (ret < 0) { 2242 return ret; 2243 } 2244 2245 if (!c->has_backup_perm) { 2246 c->has_backup_perm = true; 2247 c->backup_perm = c->perm; 2248 c->backup_shared_perm = c->shared_perm; 2249 } 2250 /* 2251 * Note: it's OK if c->has_backup_perm was already set, as we can find the 2252 * same child twice during check_perm procedure 2253 */ 2254 2255 c->perm = perm; 2256 c->shared_perm = shared; 2257 2258 return 0; 2259 } 2260 2261 static void bdrv_child_set_perm(BdrvChild *c) 2262 { 2263 c->has_backup_perm = false; 2264 2265 bdrv_set_perm(c->bs); 2266 } 2267 2268 static void bdrv_child_abort_perm_update(BdrvChild *c) 2269 { 2270 if (c->has_backup_perm) { 2271 c->perm = c->backup_perm; 2272 c->shared_perm = c->backup_shared_perm; 2273 c->has_backup_perm = false; 2274 } 2275 2276 bdrv_abort_perm_update(c->bs); 2277 } 2278 2279 static int bdrv_refresh_perms(BlockDriverState *bs, Error **errp) 2280 { 2281 int ret; 2282 uint64_t perm, shared_perm; 2283 2284 bdrv_get_cumulative_perm(bs, &perm, &shared_perm); 2285 ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, errp); 2286 if (ret < 0) { 2287 bdrv_abort_perm_update(bs); 2288 return ret; 2289 } 2290 bdrv_set_perm(bs); 2291 2292 return 0; 2293 } 2294 2295 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, 2296 Error **errp) 2297 { 2298 Error *local_err = NULL; 2299 int ret; 2300 2301 ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL, &local_err); 2302 if (ret < 0) { 2303 bdrv_child_abort_perm_update(c); 2304 if ((perm & ~c->perm) || (c->shared_perm & ~shared)) { 2305 /* tighten permissions */ 2306 error_propagate(errp, local_err); 2307 } else { 2308 /* 2309 * Our caller may intend to only loosen restrictions and 2310 * does not expect this function to fail. Errors are not 2311 * fatal in such a case, so we can just hide them from our 2312 * caller. 2313 */ 2314 error_free(local_err); 2315 ret = 0; 2316 } 2317 return ret; 2318 } 2319 2320 bdrv_child_set_perm(c); 2321 2322 return 0; 2323 } 2324 2325 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp) 2326 { 2327 uint64_t parent_perms, parent_shared; 2328 uint64_t perms, shared; 2329 2330 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared); 2331 bdrv_child_perm(bs, c->bs, c, c->role, NULL, 2332 parent_perms, parent_shared, &perms, &shared); 2333 2334 return bdrv_child_try_set_perm(c, perms, shared, errp); 2335 } 2336 2337 /* 2338 * Default implementation for .bdrv_child_perm() for block filters: 2339 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the 2340 * filtered child. 2341 */ 2342 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c, 2343 BdrvChildRole role, 2344 BlockReopenQueue *reopen_queue, 2345 uint64_t perm, uint64_t shared, 2346 uint64_t *nperm, uint64_t *nshared) 2347 { 2348 *nperm = perm & DEFAULT_PERM_PASSTHROUGH; 2349 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED; 2350 } 2351 2352 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c, 2353 BdrvChildRole role, 2354 BlockReopenQueue *reopen_queue, 2355 uint64_t perm, uint64_t shared, 2356 uint64_t *nperm, uint64_t *nshared) 2357 { 2358 assert(role & BDRV_CHILD_COW); 2359 2360 /* 2361 * We want consistent read from backing files if the parent needs it. 2362 * No other operations are performed on backing files. 2363 */ 2364 perm &= BLK_PERM_CONSISTENT_READ; 2365 2366 /* 2367 * If the parent can deal with changing data, we're okay with a 2368 * writable and resizable backing file. 2369 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? 2370 */ 2371 if (shared & BLK_PERM_WRITE) { 2372 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE; 2373 } else { 2374 shared = 0; 2375 } 2376 2377 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD | 2378 BLK_PERM_WRITE_UNCHANGED; 2379 2380 if (bs->open_flags & BDRV_O_INACTIVE) { 2381 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2382 } 2383 2384 *nperm = perm; 2385 *nshared = shared; 2386 } 2387 2388 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c, 2389 BdrvChildRole role, 2390 BlockReopenQueue *reopen_queue, 2391 uint64_t perm, uint64_t shared, 2392 uint64_t *nperm, uint64_t *nshared) 2393 { 2394 int flags; 2395 2396 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)); 2397 2398 flags = bdrv_reopen_get_flags(reopen_queue, bs); 2399 2400 /* 2401 * Apart from the modifications below, the same permissions are 2402 * forwarded and left alone as for filters 2403 */ 2404 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2405 perm, shared, &perm, &shared); 2406 2407 if (role & BDRV_CHILD_METADATA) { 2408 /* Format drivers may touch metadata even if the guest doesn't write */ 2409 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) { 2410 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2411 } 2412 2413 /* 2414 * bs->file always needs to be consistent because of the 2415 * metadata. We can never allow other users to resize or write 2416 * to it. 2417 */ 2418 if (!(flags & BDRV_O_NO_IO)) { 2419 perm |= BLK_PERM_CONSISTENT_READ; 2420 } 2421 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); 2422 } 2423 2424 if (role & BDRV_CHILD_DATA) { 2425 /* 2426 * Technically, everything in this block is a subset of the 2427 * BDRV_CHILD_METADATA path taken above, and so this could 2428 * be an "else if" branch. However, that is not obvious, and 2429 * this function is not performance critical, therefore we let 2430 * this be an independent "if". 2431 */ 2432 2433 /* 2434 * We cannot allow other users to resize the file because the 2435 * format driver might have some assumptions about the size 2436 * (e.g. because it is stored in metadata, or because the file 2437 * is split into fixed-size data files). 2438 */ 2439 shared &= ~BLK_PERM_RESIZE; 2440 2441 /* 2442 * WRITE_UNCHANGED often cannot be performed as such on the 2443 * data file. For example, the qcow2 driver may still need to 2444 * write copied clusters on copy-on-read. 2445 */ 2446 if (perm & BLK_PERM_WRITE_UNCHANGED) { 2447 perm |= BLK_PERM_WRITE; 2448 } 2449 2450 /* 2451 * If the data file is written to, the format driver may 2452 * expect to be able to resize it by writing beyond the EOF. 2453 */ 2454 if (perm & BLK_PERM_WRITE) { 2455 perm |= BLK_PERM_RESIZE; 2456 } 2457 } 2458 2459 if (bs->open_flags & BDRV_O_INACTIVE) { 2460 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2461 } 2462 2463 *nperm = perm; 2464 *nshared = shared; 2465 } 2466 2467 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c, 2468 BdrvChildRole role, BlockReopenQueue *reopen_queue, 2469 uint64_t perm, uint64_t shared, 2470 uint64_t *nperm, uint64_t *nshared) 2471 { 2472 if (role & BDRV_CHILD_FILTERED) { 2473 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | 2474 BDRV_CHILD_COW))); 2475 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2476 perm, shared, nperm, nshared); 2477 } else if (role & BDRV_CHILD_COW) { 2478 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA))); 2479 bdrv_default_perms_for_cow(bs, c, role, reopen_queue, 2480 perm, shared, nperm, nshared); 2481 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) { 2482 bdrv_default_perms_for_storage(bs, c, role, reopen_queue, 2483 perm, shared, nperm, nshared); 2484 } else { 2485 g_assert_not_reached(); 2486 } 2487 } 2488 2489 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) 2490 { 2491 static const uint64_t permissions[] = { 2492 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ, 2493 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE, 2494 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED, 2495 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE, 2496 [BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD, 2497 }; 2498 2499 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX); 2500 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1); 2501 2502 assert(qapi_perm < BLOCK_PERMISSION__MAX); 2503 2504 return permissions[qapi_perm]; 2505 } 2506 2507 static void bdrv_replace_child_noperm(BdrvChild *child, 2508 BlockDriverState *new_bs) 2509 { 2510 BlockDriverState *old_bs = child->bs; 2511 int new_bs_quiesce_counter; 2512 int drain_saldo; 2513 2514 assert(!child->frozen); 2515 2516 if (old_bs && new_bs) { 2517 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs)); 2518 } 2519 2520 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); 2521 drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter; 2522 2523 /* 2524 * If the new child node is drained but the old one was not, flush 2525 * all outstanding requests to the old child node. 2526 */ 2527 while (drain_saldo > 0 && child->klass->drained_begin) { 2528 bdrv_parent_drained_begin_single(child, true); 2529 drain_saldo--; 2530 } 2531 2532 if (old_bs) { 2533 /* Detach first so that the recursive drain sections coming from @child 2534 * are already gone and we only end the drain sections that came from 2535 * elsewhere. */ 2536 if (child->klass->detach) { 2537 child->klass->detach(child); 2538 } 2539 QLIST_REMOVE(child, next_parent); 2540 } 2541 2542 child->bs = new_bs; 2543 2544 if (new_bs) { 2545 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); 2546 2547 /* 2548 * Detaching the old node may have led to the new node's 2549 * quiesce_counter having been decreased. Not a problem, we 2550 * just need to recognize this here and then invoke 2551 * drained_end appropriately more often. 2552 */ 2553 assert(new_bs->quiesce_counter <= new_bs_quiesce_counter); 2554 drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter; 2555 2556 /* Attach only after starting new drained sections, so that recursive 2557 * drain sections coming from @child don't get an extra .drained_begin 2558 * callback. */ 2559 if (child->klass->attach) { 2560 child->klass->attach(child); 2561 } 2562 } 2563 2564 /* 2565 * If the old child node was drained but the new one is not, allow 2566 * requests to come in only after the new node has been attached. 2567 */ 2568 while (drain_saldo < 0 && child->klass->drained_end) { 2569 bdrv_parent_drained_end_single(child); 2570 drain_saldo++; 2571 } 2572 } 2573 2574 /* 2575 * Updates @child to change its reference to point to @new_bs, including 2576 * checking and applying the necessary permission updates both to the old node 2577 * and to @new_bs. 2578 * 2579 * NULL is passed as @new_bs for removing the reference before freeing @child. 2580 * 2581 * If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this 2582 * function uses bdrv_set_perm() to update the permissions according to the new 2583 * reference that @new_bs gets. 2584 * 2585 * Callers must ensure that child->frozen is false. 2586 */ 2587 static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs) 2588 { 2589 BlockDriverState *old_bs = child->bs; 2590 2591 /* Asserts that child->frozen == false */ 2592 bdrv_replace_child_noperm(child, new_bs); 2593 2594 /* 2595 * Start with the new node's permissions. If @new_bs is a (direct 2596 * or indirect) child of @old_bs, we must complete the permission 2597 * update on @new_bs before we loosen the restrictions on @old_bs. 2598 * Otherwise, bdrv_check_perm() on @old_bs would re-initiate 2599 * updating the permissions of @new_bs, and thus not purely loosen 2600 * restrictions. 2601 */ 2602 if (new_bs) { 2603 bdrv_set_perm(new_bs); 2604 } 2605 2606 if (old_bs) { 2607 /* 2608 * Update permissions for old node. We're just taking a parent away, so 2609 * we're loosening restrictions. Errors of permission update are not 2610 * fatal in this case, ignore them. 2611 */ 2612 bdrv_refresh_perms(old_bs, NULL); 2613 2614 /* When the parent requiring a non-default AioContext is removed, the 2615 * node moves back to the main AioContext */ 2616 bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL); 2617 } 2618 } 2619 2620 /* 2621 * This function steals the reference to child_bs from the caller. 2622 * That reference is later dropped by bdrv_root_unref_child(). 2623 * 2624 * On failure NULL is returned, errp is set and the reference to 2625 * child_bs is also dropped. 2626 * 2627 * The caller must hold the AioContext lock @child_bs, but not that of @ctx 2628 * (unless @child_bs is already in @ctx). 2629 */ 2630 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, 2631 const char *child_name, 2632 const BdrvChildClass *child_class, 2633 BdrvChildRole child_role, 2634 AioContext *ctx, 2635 uint64_t perm, uint64_t shared_perm, 2636 void *opaque, Error **errp) 2637 { 2638 BdrvChild *child; 2639 Error *local_err = NULL; 2640 int ret; 2641 2642 ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, errp); 2643 if (ret < 0) { 2644 bdrv_abort_perm_update(child_bs); 2645 bdrv_unref(child_bs); 2646 return NULL; 2647 } 2648 2649 child = g_new(BdrvChild, 1); 2650 *child = (BdrvChild) { 2651 .bs = NULL, 2652 .name = g_strdup(child_name), 2653 .klass = child_class, 2654 .role = child_role, 2655 .perm = perm, 2656 .shared_perm = shared_perm, 2657 .opaque = opaque, 2658 }; 2659 2660 /* If the AioContexts don't match, first try to move the subtree of 2661 * child_bs into the AioContext of the new parent. If this doesn't work, 2662 * try moving the parent into the AioContext of child_bs instead. */ 2663 if (bdrv_get_aio_context(child_bs) != ctx) { 2664 ret = bdrv_try_set_aio_context(child_bs, ctx, &local_err); 2665 if (ret < 0 && child_class->can_set_aio_ctx) { 2666 GSList *ignore = g_slist_prepend(NULL, child); 2667 ctx = bdrv_get_aio_context(child_bs); 2668 if (child_class->can_set_aio_ctx(child, ctx, &ignore, NULL)) { 2669 error_free(local_err); 2670 ret = 0; 2671 g_slist_free(ignore); 2672 ignore = g_slist_prepend(NULL, child); 2673 child_class->set_aio_ctx(child, ctx, &ignore); 2674 } 2675 g_slist_free(ignore); 2676 } 2677 if (ret < 0) { 2678 error_propagate(errp, local_err); 2679 g_free(child); 2680 bdrv_abort_perm_update(child_bs); 2681 bdrv_unref(child_bs); 2682 return NULL; 2683 } 2684 } 2685 2686 /* This performs the matching bdrv_set_perm() for the above check. */ 2687 bdrv_replace_child(child, child_bs); 2688 2689 return child; 2690 } 2691 2692 /* 2693 * This function transfers the reference to child_bs from the caller 2694 * to parent_bs. That reference is later dropped by parent_bs on 2695 * bdrv_close() or if someone calls bdrv_unref_child(). 2696 * 2697 * On failure NULL is returned, errp is set and the reference to 2698 * child_bs is also dropped. 2699 * 2700 * If @parent_bs and @child_bs are in different AioContexts, the caller must 2701 * hold the AioContext lock for @child_bs, but not for @parent_bs. 2702 */ 2703 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, 2704 BlockDriverState *child_bs, 2705 const char *child_name, 2706 const BdrvChildClass *child_class, 2707 BdrvChildRole child_role, 2708 Error **errp) 2709 { 2710 BdrvChild *child; 2711 uint64_t perm, shared_perm; 2712 2713 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm); 2714 2715 assert(parent_bs->drv); 2716 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL, 2717 perm, shared_perm, &perm, &shared_perm); 2718 2719 child = bdrv_root_attach_child(child_bs, child_name, child_class, 2720 child_role, bdrv_get_aio_context(parent_bs), 2721 perm, shared_perm, parent_bs, errp); 2722 if (child == NULL) { 2723 return NULL; 2724 } 2725 2726 QLIST_INSERT_HEAD(&parent_bs->children, child, next); 2727 return child; 2728 } 2729 2730 static void bdrv_detach_child(BdrvChild *child) 2731 { 2732 QLIST_SAFE_REMOVE(child, next); 2733 2734 bdrv_replace_child(child, NULL); 2735 2736 g_free(child->name); 2737 g_free(child); 2738 } 2739 2740 /* Callers must ensure that child->frozen is false. */ 2741 void bdrv_root_unref_child(BdrvChild *child) 2742 { 2743 BlockDriverState *child_bs; 2744 2745 child_bs = child->bs; 2746 bdrv_detach_child(child); 2747 bdrv_unref(child_bs); 2748 } 2749 2750 /** 2751 * Clear all inherits_from pointers from children and grandchildren of 2752 * @root that point to @root, where necessary. 2753 */ 2754 static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child) 2755 { 2756 BdrvChild *c; 2757 2758 if (child->bs->inherits_from == root) { 2759 /* 2760 * Remove inherits_from only when the last reference between root and 2761 * child->bs goes away. 2762 */ 2763 QLIST_FOREACH(c, &root->children, next) { 2764 if (c != child && c->bs == child->bs) { 2765 break; 2766 } 2767 } 2768 if (c == NULL) { 2769 child->bs->inherits_from = NULL; 2770 } 2771 } 2772 2773 QLIST_FOREACH(c, &child->bs->children, next) { 2774 bdrv_unset_inherits_from(root, c); 2775 } 2776 } 2777 2778 /* Callers must ensure that child->frozen is false. */ 2779 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child) 2780 { 2781 if (child == NULL) { 2782 return; 2783 } 2784 2785 bdrv_unset_inherits_from(parent, child); 2786 bdrv_root_unref_child(child); 2787 } 2788 2789 2790 static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load) 2791 { 2792 BdrvChild *c; 2793 QLIST_FOREACH(c, &bs->parents, next_parent) { 2794 if (c->klass->change_media) { 2795 c->klass->change_media(c, load); 2796 } 2797 } 2798 } 2799 2800 /* Return true if you can reach parent going through child->inherits_from 2801 * recursively. If parent or child are NULL, return false */ 2802 static bool bdrv_inherits_from_recursive(BlockDriverState *child, 2803 BlockDriverState *parent) 2804 { 2805 while (child && child != parent) { 2806 child = child->inherits_from; 2807 } 2808 2809 return child != NULL; 2810 } 2811 2812 /* 2813 * Return the BdrvChildRole for @bs's backing child. bs->backing is 2814 * mostly used for COW backing children (role = COW), but also for 2815 * filtered children (role = FILTERED | PRIMARY). 2816 */ 2817 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs) 2818 { 2819 if (bs->drv && bs->drv->is_filter) { 2820 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY; 2821 } else { 2822 return BDRV_CHILD_COW; 2823 } 2824 } 2825 2826 /* 2827 * Sets the bs->backing link of a BDS. A new reference is created; callers 2828 * which don't need their own reference any more must call bdrv_unref(). 2829 */ 2830 void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, 2831 Error **errp) 2832 { 2833 bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) && 2834 bdrv_inherits_from_recursive(backing_hd, bs); 2835 2836 if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) { 2837 return; 2838 } 2839 2840 if (backing_hd) { 2841 bdrv_ref(backing_hd); 2842 } 2843 2844 if (bs->backing) { 2845 /* Cannot be frozen, we checked that above */ 2846 bdrv_unref_child(bs, bs->backing); 2847 bs->backing = NULL; 2848 } 2849 2850 if (!backing_hd) { 2851 goto out; 2852 } 2853 2854 bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds, 2855 bdrv_backing_role(bs), errp); 2856 /* If backing_hd was already part of bs's backing chain, and 2857 * inherits_from pointed recursively to bs then let's update it to 2858 * point directly to bs (else it will become NULL). */ 2859 if (bs->backing && update_inherits_from) { 2860 backing_hd->inherits_from = bs; 2861 } 2862 2863 out: 2864 bdrv_refresh_limits(bs, NULL); 2865 } 2866 2867 /* 2868 * Opens the backing file for a BlockDriverState if not yet open 2869 * 2870 * bdref_key specifies the key for the image's BlockdevRef in the options QDict. 2871 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 2872 * itself, all options starting with "${bdref_key}." are considered part of the 2873 * BlockdevRef. 2874 * 2875 * TODO Can this be unified with bdrv_open_image()? 2876 */ 2877 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, 2878 const char *bdref_key, Error **errp) 2879 { 2880 char *backing_filename = NULL; 2881 char *bdref_key_dot; 2882 const char *reference = NULL; 2883 int ret = 0; 2884 bool implicit_backing = false; 2885 BlockDriverState *backing_hd; 2886 QDict *options; 2887 QDict *tmp_parent_options = NULL; 2888 Error *local_err = NULL; 2889 2890 if (bs->backing != NULL) { 2891 goto free_exit; 2892 } 2893 2894 /* NULL means an empty set of options */ 2895 if (parent_options == NULL) { 2896 tmp_parent_options = qdict_new(); 2897 parent_options = tmp_parent_options; 2898 } 2899 2900 bs->open_flags &= ~BDRV_O_NO_BACKING; 2901 2902 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 2903 qdict_extract_subqdict(parent_options, &options, bdref_key_dot); 2904 g_free(bdref_key_dot); 2905 2906 /* 2907 * Caution: while qdict_get_try_str() is fine, getting non-string 2908 * types would require more care. When @parent_options come from 2909 * -blockdev or blockdev_add, its members are typed according to 2910 * the QAPI schema, but when they come from -drive, they're all 2911 * QString. 2912 */ 2913 reference = qdict_get_try_str(parent_options, bdref_key); 2914 if (reference || qdict_haskey(options, "file.filename")) { 2915 /* keep backing_filename NULL */ 2916 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { 2917 qobject_unref(options); 2918 goto free_exit; 2919 } else { 2920 if (qdict_size(options) == 0) { 2921 /* If the user specifies options that do not modify the 2922 * backing file's behavior, we might still consider it the 2923 * implicit backing file. But it's easier this way, and 2924 * just specifying some of the backing BDS's options is 2925 * only possible with -drive anyway (otherwise the QAPI 2926 * schema forces the user to specify everything). */ 2927 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file); 2928 } 2929 2930 backing_filename = bdrv_get_full_backing_filename(bs, &local_err); 2931 if (local_err) { 2932 ret = -EINVAL; 2933 error_propagate(errp, local_err); 2934 qobject_unref(options); 2935 goto free_exit; 2936 } 2937 } 2938 2939 if (!bs->drv || !bs->drv->supports_backing) { 2940 ret = -EINVAL; 2941 error_setg(errp, "Driver doesn't support backing files"); 2942 qobject_unref(options); 2943 goto free_exit; 2944 } 2945 2946 if (!reference && 2947 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) { 2948 qdict_put_str(options, "driver", bs->backing_format); 2949 } 2950 2951 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs, 2952 &child_of_bds, bdrv_backing_role(bs), errp); 2953 if (!backing_hd) { 2954 bs->open_flags |= BDRV_O_NO_BACKING; 2955 error_prepend(errp, "Could not open backing file: "); 2956 ret = -EINVAL; 2957 goto free_exit; 2958 } 2959 2960 if (implicit_backing) { 2961 bdrv_refresh_filename(backing_hd); 2962 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 2963 backing_hd->filename); 2964 } 2965 2966 /* Hook up the backing file link; drop our reference, bs owns the 2967 * backing_hd reference now */ 2968 bdrv_set_backing_hd(bs, backing_hd, &local_err); 2969 bdrv_unref(backing_hd); 2970 if (local_err) { 2971 error_propagate(errp, local_err); 2972 ret = -EINVAL; 2973 goto free_exit; 2974 } 2975 2976 qdict_del(parent_options, bdref_key); 2977 2978 free_exit: 2979 g_free(backing_filename); 2980 qobject_unref(tmp_parent_options); 2981 return ret; 2982 } 2983 2984 static BlockDriverState * 2985 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key, 2986 BlockDriverState *parent, const BdrvChildClass *child_class, 2987 BdrvChildRole child_role, bool allow_none, Error **errp) 2988 { 2989 BlockDriverState *bs = NULL; 2990 QDict *image_options; 2991 char *bdref_key_dot; 2992 const char *reference; 2993 2994 assert(child_class != NULL); 2995 2996 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 2997 qdict_extract_subqdict(options, &image_options, bdref_key_dot); 2998 g_free(bdref_key_dot); 2999 3000 /* 3001 * Caution: while qdict_get_try_str() is fine, getting non-string 3002 * types would require more care. When @options come from 3003 * -blockdev or blockdev_add, its members are typed according to 3004 * the QAPI schema, but when they come from -drive, they're all 3005 * QString. 3006 */ 3007 reference = qdict_get_try_str(options, bdref_key); 3008 if (!filename && !reference && !qdict_size(image_options)) { 3009 if (!allow_none) { 3010 error_setg(errp, "A block device must be specified for \"%s\"", 3011 bdref_key); 3012 } 3013 qobject_unref(image_options); 3014 goto done; 3015 } 3016 3017 bs = bdrv_open_inherit(filename, reference, image_options, 0, 3018 parent, child_class, child_role, errp); 3019 if (!bs) { 3020 goto done; 3021 } 3022 3023 done: 3024 qdict_del(options, bdref_key); 3025 return bs; 3026 } 3027 3028 /* 3029 * Opens a disk image whose options are given as BlockdevRef in another block 3030 * device's options. 3031 * 3032 * If allow_none is true, no image will be opened if filename is false and no 3033 * BlockdevRef is given. NULL will be returned, but errp remains unset. 3034 * 3035 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict. 3036 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 3037 * itself, all options starting with "${bdref_key}." are considered part of the 3038 * BlockdevRef. 3039 * 3040 * The BlockdevRef will be removed from the options QDict. 3041 */ 3042 BdrvChild *bdrv_open_child(const char *filename, 3043 QDict *options, const char *bdref_key, 3044 BlockDriverState *parent, 3045 const BdrvChildClass *child_class, 3046 BdrvChildRole child_role, 3047 bool allow_none, Error **errp) 3048 { 3049 BlockDriverState *bs; 3050 3051 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class, 3052 child_role, allow_none, errp); 3053 if (bs == NULL) { 3054 return NULL; 3055 } 3056 3057 return bdrv_attach_child(parent, bs, bdref_key, child_class, child_role, 3058 errp); 3059 } 3060 3061 /* 3062 * TODO Future callers may need to specify parent/child_class in order for 3063 * option inheritance to work. Existing callers use it for the root node. 3064 */ 3065 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp) 3066 { 3067 BlockDriverState *bs = NULL; 3068 QObject *obj = NULL; 3069 QDict *qdict = NULL; 3070 const char *reference = NULL; 3071 Visitor *v = NULL; 3072 3073 if (ref->type == QTYPE_QSTRING) { 3074 reference = ref->u.reference; 3075 } else { 3076 BlockdevOptions *options = &ref->u.definition; 3077 assert(ref->type == QTYPE_QDICT); 3078 3079 v = qobject_output_visitor_new(&obj); 3080 visit_type_BlockdevOptions(v, NULL, &options, &error_abort); 3081 visit_complete(v, &obj); 3082 3083 qdict = qobject_to(QDict, obj); 3084 qdict_flatten(qdict); 3085 3086 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for 3087 * compatibility with other callers) rather than what we want as the 3088 * real defaults. Apply the defaults here instead. */ 3089 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off"); 3090 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off"); 3091 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off"); 3092 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off"); 3093 3094 } 3095 3096 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp); 3097 obj = NULL; 3098 qobject_unref(obj); 3099 visit_free(v); 3100 return bs; 3101 } 3102 3103 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, 3104 int flags, 3105 QDict *snapshot_options, 3106 Error **errp) 3107 { 3108 /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */ 3109 char *tmp_filename = g_malloc0(PATH_MAX + 1); 3110 int64_t total_size; 3111 QemuOpts *opts = NULL; 3112 BlockDriverState *bs_snapshot = NULL; 3113 Error *local_err = NULL; 3114 int ret; 3115 3116 /* if snapshot, we create a temporary backing file and open it 3117 instead of opening 'filename' directly */ 3118 3119 /* Get the required size from the image */ 3120 total_size = bdrv_getlength(bs); 3121 if (total_size < 0) { 3122 error_setg_errno(errp, -total_size, "Could not get image size"); 3123 goto out; 3124 } 3125 3126 /* Create the temporary image */ 3127 ret = get_tmp_filename(tmp_filename, PATH_MAX + 1); 3128 if (ret < 0) { 3129 error_setg_errno(errp, -ret, "Could not get temporary filename"); 3130 goto out; 3131 } 3132 3133 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0, 3134 &error_abort); 3135 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort); 3136 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp); 3137 qemu_opts_del(opts); 3138 if (ret < 0) { 3139 error_prepend(errp, "Could not create temporary overlay '%s': ", 3140 tmp_filename); 3141 goto out; 3142 } 3143 3144 /* Prepare options QDict for the temporary file */ 3145 qdict_put_str(snapshot_options, "file.driver", "file"); 3146 qdict_put_str(snapshot_options, "file.filename", tmp_filename); 3147 qdict_put_str(snapshot_options, "driver", "qcow2"); 3148 3149 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp); 3150 snapshot_options = NULL; 3151 if (!bs_snapshot) { 3152 goto out; 3153 } 3154 3155 /* bdrv_append() consumes a strong reference to bs_snapshot 3156 * (i.e. it will call bdrv_unref() on it) even on error, so in 3157 * order to be able to return one, we have to increase 3158 * bs_snapshot's refcount here */ 3159 bdrv_ref(bs_snapshot); 3160 bdrv_append(bs_snapshot, bs, &local_err); 3161 if (local_err) { 3162 error_propagate(errp, local_err); 3163 bs_snapshot = NULL; 3164 goto out; 3165 } 3166 3167 out: 3168 qobject_unref(snapshot_options); 3169 g_free(tmp_filename); 3170 return bs_snapshot; 3171 } 3172 3173 /* 3174 * Opens a disk image (raw, qcow2, vmdk, ...) 3175 * 3176 * options is a QDict of options to pass to the block drivers, or NULL for an 3177 * empty set of options. The reference to the QDict belongs to the block layer 3178 * after the call (even on failure), so if the caller intends to reuse the 3179 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 3180 * 3181 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there. 3182 * If it is not NULL, the referenced BDS will be reused. 3183 * 3184 * The reference parameter may be used to specify an existing block device which 3185 * should be opened. If specified, neither options nor a filename may be given, 3186 * nor can an existing BDS be reused (that is, *pbs has to be NULL). 3187 */ 3188 static BlockDriverState *bdrv_open_inherit(const char *filename, 3189 const char *reference, 3190 QDict *options, int flags, 3191 BlockDriverState *parent, 3192 const BdrvChildClass *child_class, 3193 BdrvChildRole child_role, 3194 Error **errp) 3195 { 3196 int ret; 3197 BlockBackend *file = NULL; 3198 BlockDriverState *bs; 3199 BlockDriver *drv = NULL; 3200 BdrvChild *child; 3201 const char *drvname; 3202 const char *backing; 3203 Error *local_err = NULL; 3204 QDict *snapshot_options = NULL; 3205 int snapshot_flags = 0; 3206 3207 assert(!child_class || !flags); 3208 assert(!child_class == !parent); 3209 3210 if (reference) { 3211 bool options_non_empty = options ? qdict_size(options) : false; 3212 qobject_unref(options); 3213 3214 if (filename || options_non_empty) { 3215 error_setg(errp, "Cannot reference an existing block device with " 3216 "additional options or a new filename"); 3217 return NULL; 3218 } 3219 3220 bs = bdrv_lookup_bs(reference, reference, errp); 3221 if (!bs) { 3222 return NULL; 3223 } 3224 3225 bdrv_ref(bs); 3226 return bs; 3227 } 3228 3229 bs = bdrv_new(); 3230 3231 /* NULL means an empty set of options */ 3232 if (options == NULL) { 3233 options = qdict_new(); 3234 } 3235 3236 /* json: syntax counts as explicit options, as if in the QDict */ 3237 parse_json_protocol(options, &filename, &local_err); 3238 if (local_err) { 3239 goto fail; 3240 } 3241 3242 bs->explicit_options = qdict_clone_shallow(options); 3243 3244 if (child_class) { 3245 bool parent_is_format; 3246 3247 if (parent->drv) { 3248 parent_is_format = parent->drv->is_format; 3249 } else { 3250 /* 3251 * parent->drv is not set yet because this node is opened for 3252 * (potential) format probing. That means that @parent is going 3253 * to be a format node. 3254 */ 3255 parent_is_format = true; 3256 } 3257 3258 bs->inherits_from = parent; 3259 child_class->inherit_options(child_role, parent_is_format, 3260 &flags, options, 3261 parent->open_flags, parent->options); 3262 } 3263 3264 ret = bdrv_fill_options(&options, filename, &flags, &local_err); 3265 if (ret < 0) { 3266 goto fail; 3267 } 3268 3269 /* 3270 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags. 3271 * Caution: getting a boolean member of @options requires care. 3272 * When @options come from -blockdev or blockdev_add, members are 3273 * typed according to the QAPI schema, but when they come from 3274 * -drive, they're all QString. 3275 */ 3276 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") && 3277 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) { 3278 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR); 3279 } else { 3280 flags &= ~BDRV_O_RDWR; 3281 } 3282 3283 if (flags & BDRV_O_SNAPSHOT) { 3284 snapshot_options = qdict_new(); 3285 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options, 3286 flags, options); 3287 /* Let bdrv_backing_options() override "read-only" */ 3288 qdict_del(options, BDRV_OPT_READ_ONLY); 3289 bdrv_inherited_options(BDRV_CHILD_COW, true, 3290 &flags, options, flags, options); 3291 } 3292 3293 bs->open_flags = flags; 3294 bs->options = options; 3295 options = qdict_clone_shallow(options); 3296 3297 /* Find the right image format driver */ 3298 /* See cautionary note on accessing @options above */ 3299 drvname = qdict_get_try_str(options, "driver"); 3300 if (drvname) { 3301 drv = bdrv_find_format(drvname); 3302 if (!drv) { 3303 error_setg(errp, "Unknown driver: '%s'", drvname); 3304 goto fail; 3305 } 3306 } 3307 3308 assert(drvname || !(flags & BDRV_O_PROTOCOL)); 3309 3310 /* See cautionary note on accessing @options above */ 3311 backing = qdict_get_try_str(options, "backing"); 3312 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL || 3313 (backing && *backing == '\0')) 3314 { 3315 if (backing) { 3316 warn_report("Use of \"backing\": \"\" is deprecated; " 3317 "use \"backing\": null instead"); 3318 } 3319 flags |= BDRV_O_NO_BACKING; 3320 qdict_del(bs->explicit_options, "backing"); 3321 qdict_del(bs->options, "backing"); 3322 qdict_del(options, "backing"); 3323 } 3324 3325 /* Open image file without format layer. This BlockBackend is only used for 3326 * probing, the block drivers will do their own bdrv_open_child() for the 3327 * same BDS, which is why we put the node name back into options. */ 3328 if ((flags & BDRV_O_PROTOCOL) == 0) { 3329 BlockDriverState *file_bs; 3330 3331 file_bs = bdrv_open_child_bs(filename, options, "file", bs, 3332 &child_of_bds, BDRV_CHILD_IMAGE, 3333 true, &local_err); 3334 if (local_err) { 3335 goto fail; 3336 } 3337 if (file_bs != NULL) { 3338 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only 3339 * looking at the header to guess the image format. This works even 3340 * in cases where a guest would not see a consistent state. */ 3341 file = blk_new(bdrv_get_aio_context(file_bs), 0, BLK_PERM_ALL); 3342 blk_insert_bs(file, file_bs, &local_err); 3343 bdrv_unref(file_bs); 3344 if (local_err) { 3345 goto fail; 3346 } 3347 3348 qdict_put_str(options, "file", bdrv_get_node_name(file_bs)); 3349 } 3350 } 3351 3352 /* Image format probing */ 3353 bs->probed = !drv; 3354 if (!drv && file) { 3355 ret = find_image_format(file, filename, &drv, &local_err); 3356 if (ret < 0) { 3357 goto fail; 3358 } 3359 /* 3360 * This option update would logically belong in bdrv_fill_options(), 3361 * but we first need to open bs->file for the probing to work, while 3362 * opening bs->file already requires the (mostly) final set of options 3363 * so that cache mode etc. can be inherited. 3364 * 3365 * Adding the driver later is somewhat ugly, but it's not an option 3366 * that would ever be inherited, so it's correct. We just need to make 3367 * sure to update both bs->options (which has the full effective 3368 * options for bs) and options (which has file.* already removed). 3369 */ 3370 qdict_put_str(bs->options, "driver", drv->format_name); 3371 qdict_put_str(options, "driver", drv->format_name); 3372 } else if (!drv) { 3373 error_setg(errp, "Must specify either driver or file"); 3374 goto fail; 3375 } 3376 3377 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */ 3378 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open); 3379 /* file must be NULL if a protocol BDS is about to be created 3380 * (the inverse results in an error message from bdrv_open_common()) */ 3381 assert(!(flags & BDRV_O_PROTOCOL) || !file); 3382 3383 /* Open the image */ 3384 ret = bdrv_open_common(bs, file, options, &local_err); 3385 if (ret < 0) { 3386 goto fail; 3387 } 3388 3389 if (file) { 3390 blk_unref(file); 3391 file = NULL; 3392 } 3393 3394 /* If there is a backing file, use it */ 3395 if ((flags & BDRV_O_NO_BACKING) == 0) { 3396 ret = bdrv_open_backing_file(bs, options, "backing", &local_err); 3397 if (ret < 0) { 3398 goto close_and_fail; 3399 } 3400 } 3401 3402 /* Remove all children options and references 3403 * from bs->options and bs->explicit_options */ 3404 QLIST_FOREACH(child, &bs->children, next) { 3405 char *child_key_dot; 3406 child_key_dot = g_strdup_printf("%s.", child->name); 3407 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot); 3408 qdict_extract_subqdict(bs->options, NULL, child_key_dot); 3409 qdict_del(bs->explicit_options, child->name); 3410 qdict_del(bs->options, child->name); 3411 g_free(child_key_dot); 3412 } 3413 3414 /* Check if any unknown options were used */ 3415 if (qdict_size(options) != 0) { 3416 const QDictEntry *entry = qdict_first(options); 3417 if (flags & BDRV_O_PROTOCOL) { 3418 error_setg(errp, "Block protocol '%s' doesn't support the option " 3419 "'%s'", drv->format_name, entry->key); 3420 } else { 3421 error_setg(errp, 3422 "Block format '%s' does not support the option '%s'", 3423 drv->format_name, entry->key); 3424 } 3425 3426 goto close_and_fail; 3427 } 3428 3429 bdrv_parent_cb_change_media(bs, true); 3430 3431 qobject_unref(options); 3432 options = NULL; 3433 3434 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the 3435 * temporary snapshot afterwards. */ 3436 if (snapshot_flags) { 3437 BlockDriverState *snapshot_bs; 3438 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags, 3439 snapshot_options, &local_err); 3440 snapshot_options = NULL; 3441 if (local_err) { 3442 goto close_and_fail; 3443 } 3444 /* We are not going to return bs but the overlay on top of it 3445 * (snapshot_bs); thus, we have to drop the strong reference to bs 3446 * (which we obtained by calling bdrv_new()). bs will not be deleted, 3447 * though, because the overlay still has a reference to it. */ 3448 bdrv_unref(bs); 3449 bs = snapshot_bs; 3450 } 3451 3452 return bs; 3453 3454 fail: 3455 blk_unref(file); 3456 qobject_unref(snapshot_options); 3457 qobject_unref(bs->explicit_options); 3458 qobject_unref(bs->options); 3459 qobject_unref(options); 3460 bs->options = NULL; 3461 bs->explicit_options = NULL; 3462 bdrv_unref(bs); 3463 error_propagate(errp, local_err); 3464 return NULL; 3465 3466 close_and_fail: 3467 bdrv_unref(bs); 3468 qobject_unref(snapshot_options); 3469 qobject_unref(options); 3470 error_propagate(errp, local_err); 3471 return NULL; 3472 } 3473 3474 BlockDriverState *bdrv_open(const char *filename, const char *reference, 3475 QDict *options, int flags, Error **errp) 3476 { 3477 return bdrv_open_inherit(filename, reference, options, flags, NULL, 3478 NULL, 0, errp); 3479 } 3480 3481 /* Return true if the NULL-terminated @list contains @str */ 3482 static bool is_str_in_list(const char *str, const char *const *list) 3483 { 3484 if (str && list) { 3485 int i; 3486 for (i = 0; list[i] != NULL; i++) { 3487 if (!strcmp(str, list[i])) { 3488 return true; 3489 } 3490 } 3491 } 3492 return false; 3493 } 3494 3495 /* 3496 * Check that every option set in @bs->options is also set in 3497 * @new_opts. 3498 * 3499 * Options listed in the common_options list and in 3500 * @bs->drv->mutable_opts are skipped. 3501 * 3502 * Return 0 on success, otherwise return -EINVAL and set @errp. 3503 */ 3504 static int bdrv_reset_options_allowed(BlockDriverState *bs, 3505 const QDict *new_opts, Error **errp) 3506 { 3507 const QDictEntry *e; 3508 /* These options are common to all block drivers and are handled 3509 * in bdrv_reopen_prepare() so they can be left out of @new_opts */ 3510 const char *const common_options[] = { 3511 "node-name", "discard", "cache.direct", "cache.no-flush", 3512 "read-only", "auto-read-only", "detect-zeroes", NULL 3513 }; 3514 3515 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) { 3516 if (!qdict_haskey(new_opts, e->key) && 3517 !is_str_in_list(e->key, common_options) && 3518 !is_str_in_list(e->key, bs->drv->mutable_opts)) { 3519 error_setg(errp, "Option '%s' cannot be reset " 3520 "to its default value", e->key); 3521 return -EINVAL; 3522 } 3523 } 3524 3525 return 0; 3526 } 3527 3528 /* 3529 * Returns true if @child can be reached recursively from @bs 3530 */ 3531 static bool bdrv_recurse_has_child(BlockDriverState *bs, 3532 BlockDriverState *child) 3533 { 3534 BdrvChild *c; 3535 3536 if (bs == child) { 3537 return true; 3538 } 3539 3540 QLIST_FOREACH(c, &bs->children, next) { 3541 if (bdrv_recurse_has_child(c->bs, child)) { 3542 return true; 3543 } 3544 } 3545 3546 return false; 3547 } 3548 3549 /* 3550 * Adds a BlockDriverState to a simple queue for an atomic, transactional 3551 * reopen of multiple devices. 3552 * 3553 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT 3554 * already performed, or alternatively may be NULL a new BlockReopenQueue will 3555 * be created and initialized. This newly created BlockReopenQueue should be 3556 * passed back in for subsequent calls that are intended to be of the same 3557 * atomic 'set'. 3558 * 3559 * bs is the BlockDriverState to add to the reopen queue. 3560 * 3561 * options contains the changed options for the associated bs 3562 * (the BlockReopenQueue takes ownership) 3563 * 3564 * flags contains the open flags for the associated bs 3565 * 3566 * returns a pointer to bs_queue, which is either the newly allocated 3567 * bs_queue, or the existing bs_queue being used. 3568 * 3569 * bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple(). 3570 */ 3571 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue, 3572 BlockDriverState *bs, 3573 QDict *options, 3574 const BdrvChildClass *klass, 3575 BdrvChildRole role, 3576 bool parent_is_format, 3577 QDict *parent_options, 3578 int parent_flags, 3579 bool keep_old_opts) 3580 { 3581 assert(bs != NULL); 3582 3583 BlockReopenQueueEntry *bs_entry; 3584 BdrvChild *child; 3585 QDict *old_options, *explicit_options, *options_copy; 3586 int flags; 3587 QemuOpts *opts; 3588 3589 /* Make sure that the caller remembered to use a drained section. This is 3590 * important to avoid graph changes between the recursive queuing here and 3591 * bdrv_reopen_multiple(). */ 3592 assert(bs->quiesce_counter > 0); 3593 3594 if (bs_queue == NULL) { 3595 bs_queue = g_new0(BlockReopenQueue, 1); 3596 QTAILQ_INIT(bs_queue); 3597 } 3598 3599 if (!options) { 3600 options = qdict_new(); 3601 } 3602 3603 /* Check if this BlockDriverState is already in the queue */ 3604 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 3605 if (bs == bs_entry->state.bs) { 3606 break; 3607 } 3608 } 3609 3610 /* 3611 * Precedence of options: 3612 * 1. Explicitly passed in options (highest) 3613 * 2. Retained from explicitly set options of bs 3614 * 3. Inherited from parent node 3615 * 4. Retained from effective options of bs 3616 */ 3617 3618 /* Old explicitly set values (don't overwrite by inherited value) */ 3619 if (bs_entry || keep_old_opts) { 3620 old_options = qdict_clone_shallow(bs_entry ? 3621 bs_entry->state.explicit_options : 3622 bs->explicit_options); 3623 bdrv_join_options(bs, options, old_options); 3624 qobject_unref(old_options); 3625 } 3626 3627 explicit_options = qdict_clone_shallow(options); 3628 3629 /* Inherit from parent node */ 3630 if (parent_options) { 3631 flags = 0; 3632 klass->inherit_options(role, parent_is_format, &flags, options, 3633 parent_flags, parent_options); 3634 } else { 3635 flags = bdrv_get_flags(bs); 3636 } 3637 3638 if (keep_old_opts) { 3639 /* Old values are used for options that aren't set yet */ 3640 old_options = qdict_clone_shallow(bs->options); 3641 bdrv_join_options(bs, options, old_options); 3642 qobject_unref(old_options); 3643 } 3644 3645 /* We have the final set of options so let's update the flags */ 3646 options_copy = qdict_clone_shallow(options); 3647 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 3648 qemu_opts_absorb_qdict(opts, options_copy, NULL); 3649 update_flags_from_options(&flags, opts); 3650 qemu_opts_del(opts); 3651 qobject_unref(options_copy); 3652 3653 /* bdrv_open_inherit() sets and clears some additional flags internally */ 3654 flags &= ~BDRV_O_PROTOCOL; 3655 if (flags & BDRV_O_RDWR) { 3656 flags |= BDRV_O_ALLOW_RDWR; 3657 } 3658 3659 if (!bs_entry) { 3660 bs_entry = g_new0(BlockReopenQueueEntry, 1); 3661 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry); 3662 } else { 3663 qobject_unref(bs_entry->state.options); 3664 qobject_unref(bs_entry->state.explicit_options); 3665 } 3666 3667 bs_entry->state.bs = bs; 3668 bs_entry->state.options = options; 3669 bs_entry->state.explicit_options = explicit_options; 3670 bs_entry->state.flags = flags; 3671 3672 /* This needs to be overwritten in bdrv_reopen_prepare() */ 3673 bs_entry->state.perm = UINT64_MAX; 3674 bs_entry->state.shared_perm = 0; 3675 3676 /* 3677 * If keep_old_opts is false then it means that unspecified 3678 * options must be reset to their original value. We don't allow 3679 * resetting 'backing' but we need to know if the option is 3680 * missing in order to decide if we have to return an error. 3681 */ 3682 if (!keep_old_opts) { 3683 bs_entry->state.backing_missing = 3684 !qdict_haskey(options, "backing") && 3685 !qdict_haskey(options, "backing.driver"); 3686 } 3687 3688 QLIST_FOREACH(child, &bs->children, next) { 3689 QDict *new_child_options = NULL; 3690 bool child_keep_old = keep_old_opts; 3691 3692 /* reopen can only change the options of block devices that were 3693 * implicitly created and inherited options. For other (referenced) 3694 * block devices, a syntax like "backing.foo" results in an error. */ 3695 if (child->bs->inherits_from != bs) { 3696 continue; 3697 } 3698 3699 /* Check if the options contain a child reference */ 3700 if (qdict_haskey(options, child->name)) { 3701 const char *childref = qdict_get_try_str(options, child->name); 3702 /* 3703 * The current child must not be reopened if the child 3704 * reference is null or points to a different node. 3705 */ 3706 if (g_strcmp0(childref, child->bs->node_name)) { 3707 continue; 3708 } 3709 /* 3710 * If the child reference points to the current child then 3711 * reopen it with its existing set of options (note that 3712 * it can still inherit new options from the parent). 3713 */ 3714 child_keep_old = true; 3715 } else { 3716 /* Extract child options ("child-name.*") */ 3717 char *child_key_dot = g_strdup_printf("%s.", child->name); 3718 qdict_extract_subqdict(explicit_options, NULL, child_key_dot); 3719 qdict_extract_subqdict(options, &new_child_options, child_key_dot); 3720 g_free(child_key_dot); 3721 } 3722 3723 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options, 3724 child->klass, child->role, bs->drv->is_format, 3725 options, flags, child_keep_old); 3726 } 3727 3728 return bs_queue; 3729 } 3730 3731 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue, 3732 BlockDriverState *bs, 3733 QDict *options, bool keep_old_opts) 3734 { 3735 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false, 3736 NULL, 0, keep_old_opts); 3737 } 3738 3739 /* 3740 * Reopen multiple BlockDriverStates atomically & transactionally. 3741 * 3742 * The queue passed in (bs_queue) must have been built up previous 3743 * via bdrv_reopen_queue(). 3744 * 3745 * Reopens all BDS specified in the queue, with the appropriate 3746 * flags. All devices are prepared for reopen, and failure of any 3747 * device will cause all device changes to be abandoned, and intermediate 3748 * data cleaned up. 3749 * 3750 * If all devices prepare successfully, then the changes are committed 3751 * to all devices. 3752 * 3753 * All affected nodes must be drained between bdrv_reopen_queue() and 3754 * bdrv_reopen_multiple(). 3755 */ 3756 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) 3757 { 3758 int ret = -1; 3759 BlockReopenQueueEntry *bs_entry, *next; 3760 3761 assert(bs_queue != NULL); 3762 3763 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 3764 assert(bs_entry->state.bs->quiesce_counter > 0); 3765 if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, errp)) { 3766 goto cleanup; 3767 } 3768 bs_entry->prepared = true; 3769 } 3770 3771 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 3772 BDRVReopenState *state = &bs_entry->state; 3773 ret = bdrv_check_perm(state->bs, bs_queue, state->perm, 3774 state->shared_perm, NULL, errp); 3775 if (ret < 0) { 3776 goto cleanup_perm; 3777 } 3778 /* Check if new_backing_bs would accept the new permissions */ 3779 if (state->replace_backing_bs && state->new_backing_bs) { 3780 uint64_t nperm, nshared; 3781 bdrv_child_perm(state->bs, state->new_backing_bs, 3782 NULL, bdrv_backing_role(state->bs), 3783 bs_queue, state->perm, state->shared_perm, 3784 &nperm, &nshared); 3785 ret = bdrv_check_update_perm(state->new_backing_bs, NULL, 3786 nperm, nshared, NULL, errp); 3787 if (ret < 0) { 3788 goto cleanup_perm; 3789 } 3790 } 3791 bs_entry->perms_checked = true; 3792 } 3793 3794 /* 3795 * If we reach this point, we have success and just need to apply the 3796 * changes. 3797 * 3798 * Reverse order is used to comfort qcow2 driver: on commit it need to write 3799 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But 3800 * children are usually goes after parents in reopen-queue, so go from last 3801 * to first element. 3802 */ 3803 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 3804 bdrv_reopen_commit(&bs_entry->state); 3805 } 3806 3807 ret = 0; 3808 cleanup_perm: 3809 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 3810 BDRVReopenState *state = &bs_entry->state; 3811 3812 if (!bs_entry->perms_checked) { 3813 continue; 3814 } 3815 3816 if (ret == 0) { 3817 uint64_t perm, shared; 3818 3819 bdrv_get_cumulative_perm(state->bs, &perm, &shared); 3820 assert(perm == state->perm); 3821 assert(shared == state->shared_perm); 3822 3823 bdrv_set_perm(state->bs); 3824 } else { 3825 bdrv_abort_perm_update(state->bs); 3826 if (state->replace_backing_bs && state->new_backing_bs) { 3827 bdrv_abort_perm_update(state->new_backing_bs); 3828 } 3829 } 3830 } 3831 3832 if (ret == 0) { 3833 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 3834 BlockDriverState *bs = bs_entry->state.bs; 3835 3836 if (bs->drv->bdrv_reopen_commit_post) 3837 bs->drv->bdrv_reopen_commit_post(&bs_entry->state); 3838 } 3839 } 3840 cleanup: 3841 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 3842 if (ret) { 3843 if (bs_entry->prepared) { 3844 bdrv_reopen_abort(&bs_entry->state); 3845 } 3846 qobject_unref(bs_entry->state.explicit_options); 3847 qobject_unref(bs_entry->state.options); 3848 } 3849 if (bs_entry->state.new_backing_bs) { 3850 bdrv_unref(bs_entry->state.new_backing_bs); 3851 } 3852 g_free(bs_entry); 3853 } 3854 g_free(bs_queue); 3855 3856 return ret; 3857 } 3858 3859 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only, 3860 Error **errp) 3861 { 3862 int ret; 3863 BlockReopenQueue *queue; 3864 QDict *opts = qdict_new(); 3865 3866 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only); 3867 3868 bdrv_subtree_drained_begin(bs); 3869 queue = bdrv_reopen_queue(NULL, bs, opts, true); 3870 ret = bdrv_reopen_multiple(queue, errp); 3871 bdrv_subtree_drained_end(bs); 3872 3873 return ret; 3874 } 3875 3876 static BlockReopenQueueEntry *find_parent_in_reopen_queue(BlockReopenQueue *q, 3877 BdrvChild *c) 3878 { 3879 BlockReopenQueueEntry *entry; 3880 3881 QTAILQ_FOREACH(entry, q, entry) { 3882 BlockDriverState *bs = entry->state.bs; 3883 BdrvChild *child; 3884 3885 QLIST_FOREACH(child, &bs->children, next) { 3886 if (child == c) { 3887 return entry; 3888 } 3889 } 3890 } 3891 3892 return NULL; 3893 } 3894 3895 static void bdrv_reopen_perm(BlockReopenQueue *q, BlockDriverState *bs, 3896 uint64_t *perm, uint64_t *shared) 3897 { 3898 BdrvChild *c; 3899 BlockReopenQueueEntry *parent; 3900 uint64_t cumulative_perms = 0; 3901 uint64_t cumulative_shared_perms = BLK_PERM_ALL; 3902 3903 QLIST_FOREACH(c, &bs->parents, next_parent) { 3904 parent = find_parent_in_reopen_queue(q, c); 3905 if (!parent) { 3906 cumulative_perms |= c->perm; 3907 cumulative_shared_perms &= c->shared_perm; 3908 } else { 3909 uint64_t nperm, nshared; 3910 3911 bdrv_child_perm(parent->state.bs, bs, c, c->role, q, 3912 parent->state.perm, parent->state.shared_perm, 3913 &nperm, &nshared); 3914 3915 cumulative_perms |= nperm; 3916 cumulative_shared_perms &= nshared; 3917 } 3918 } 3919 *perm = cumulative_perms; 3920 *shared = cumulative_shared_perms; 3921 } 3922 3923 static bool bdrv_reopen_can_attach(BlockDriverState *parent, 3924 BdrvChild *child, 3925 BlockDriverState *new_child, 3926 Error **errp) 3927 { 3928 AioContext *parent_ctx = bdrv_get_aio_context(parent); 3929 AioContext *child_ctx = bdrv_get_aio_context(new_child); 3930 GSList *ignore; 3931 bool ret; 3932 3933 ignore = g_slist_prepend(NULL, child); 3934 ret = bdrv_can_set_aio_context(new_child, parent_ctx, &ignore, NULL); 3935 g_slist_free(ignore); 3936 if (ret) { 3937 return ret; 3938 } 3939 3940 ignore = g_slist_prepend(NULL, child); 3941 ret = bdrv_can_set_aio_context(parent, child_ctx, &ignore, errp); 3942 g_slist_free(ignore); 3943 return ret; 3944 } 3945 3946 /* 3947 * Take a BDRVReopenState and check if the value of 'backing' in the 3948 * reopen_state->options QDict is valid or not. 3949 * 3950 * If 'backing' is missing from the QDict then return 0. 3951 * 3952 * If 'backing' contains the node name of the backing file of 3953 * reopen_state->bs then return 0. 3954 * 3955 * If 'backing' contains a different node name (or is null) then check 3956 * whether the current backing file can be replaced with the new one. 3957 * If that's the case then reopen_state->replace_backing_bs is set to 3958 * true and reopen_state->new_backing_bs contains a pointer to the new 3959 * backing BlockDriverState (or NULL). 3960 * 3961 * Return 0 on success, otherwise return < 0 and set @errp. 3962 */ 3963 static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, 3964 Error **errp) 3965 { 3966 BlockDriverState *bs = reopen_state->bs; 3967 BlockDriverState *overlay_bs, *below_bs, *new_backing_bs; 3968 QObject *value; 3969 const char *str; 3970 3971 value = qdict_get(reopen_state->options, "backing"); 3972 if (value == NULL) { 3973 return 0; 3974 } 3975 3976 switch (qobject_type(value)) { 3977 case QTYPE_QNULL: 3978 new_backing_bs = NULL; 3979 break; 3980 case QTYPE_QSTRING: 3981 str = qstring_get_str(qobject_to(QString, value)); 3982 new_backing_bs = bdrv_lookup_bs(NULL, str, errp); 3983 if (new_backing_bs == NULL) { 3984 return -EINVAL; 3985 } else if (bdrv_recurse_has_child(new_backing_bs, bs)) { 3986 error_setg(errp, "Making '%s' a backing file of '%s' " 3987 "would create a cycle", str, bs->node_name); 3988 return -EINVAL; 3989 } 3990 break; 3991 default: 3992 /* 'backing' does not allow any other data type */ 3993 g_assert_not_reached(); 3994 } 3995 3996 /* 3997 * Check AioContext compatibility so that the bdrv_set_backing_hd() call in 3998 * bdrv_reopen_commit() won't fail. 3999 */ 4000 if (new_backing_bs) { 4001 if (!bdrv_reopen_can_attach(bs, bs->backing, new_backing_bs, errp)) { 4002 return -EINVAL; 4003 } 4004 } 4005 4006 /* 4007 * Ensure that @bs can really handle backing files, because we are 4008 * about to give it one (or swap the existing one) 4009 */ 4010 if (bs->drv->is_filter) { 4011 /* Filters always have a file or a backing child */ 4012 if (!bs->backing) { 4013 error_setg(errp, "'%s' is a %s filter node that does not support a " 4014 "backing child", bs->node_name, bs->drv->format_name); 4015 return -EINVAL; 4016 } 4017 } else if (!bs->drv->supports_backing) { 4018 error_setg(errp, "Driver '%s' of node '%s' does not support backing " 4019 "files", bs->drv->format_name, bs->node_name); 4020 return -EINVAL; 4021 } 4022 4023 /* 4024 * Find the "actual" backing file by skipping all links that point 4025 * to an implicit node, if any (e.g. a commit filter node). 4026 * We cannot use any of the bdrv_skip_*() functions here because 4027 * those return the first explicit node, while we are looking for 4028 * its overlay here. 4029 */ 4030 overlay_bs = bs; 4031 for (below_bs = bdrv_filter_or_cow_bs(overlay_bs); 4032 below_bs && below_bs->implicit; 4033 below_bs = bdrv_filter_or_cow_bs(overlay_bs)) 4034 { 4035 overlay_bs = below_bs; 4036 } 4037 4038 /* If we want to replace the backing file we need some extra checks */ 4039 if (new_backing_bs != bdrv_filter_or_cow_bs(overlay_bs)) { 4040 /* Check for implicit nodes between bs and its backing file */ 4041 if (bs != overlay_bs) { 4042 error_setg(errp, "Cannot change backing link if '%s' has " 4043 "an implicit backing file", bs->node_name); 4044 return -EPERM; 4045 } 4046 /* 4047 * Check if the backing link that we want to replace is frozen. 4048 * Note that 4049 * bdrv_filter_or_cow_child(overlay_bs) == overlay_bs->backing, 4050 * because we know that overlay_bs == bs, and that @bs 4051 * either is a filter that uses ->backing or a COW format BDS 4052 * with bs->drv->supports_backing == true. 4053 */ 4054 if (bdrv_is_backing_chain_frozen(overlay_bs, 4055 child_bs(overlay_bs->backing), errp)) 4056 { 4057 return -EPERM; 4058 } 4059 reopen_state->replace_backing_bs = true; 4060 if (new_backing_bs) { 4061 bdrv_ref(new_backing_bs); 4062 reopen_state->new_backing_bs = new_backing_bs; 4063 } 4064 } 4065 4066 return 0; 4067 } 4068 4069 /* 4070 * Prepares a BlockDriverState for reopen. All changes are staged in the 4071 * 'opaque' field of the BDRVReopenState, which is used and allocated by 4072 * the block driver layer .bdrv_reopen_prepare() 4073 * 4074 * bs is the BlockDriverState to reopen 4075 * flags are the new open flags 4076 * queue is the reopen queue 4077 * 4078 * Returns 0 on success, non-zero on error. On error errp will be set 4079 * as well. 4080 * 4081 * On failure, bdrv_reopen_abort() will be called to clean up any data. 4082 * It is the responsibility of the caller to then call the abort() or 4083 * commit() for any other BDS that have been left in a prepare() state 4084 * 4085 */ 4086 int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, 4087 Error **errp) 4088 { 4089 int ret = -1; 4090 int old_flags; 4091 Error *local_err = NULL; 4092 BlockDriver *drv; 4093 QemuOpts *opts; 4094 QDict *orig_reopen_opts; 4095 char *discard = NULL; 4096 bool read_only; 4097 bool drv_prepared = false; 4098 4099 assert(reopen_state != NULL); 4100 assert(reopen_state->bs->drv != NULL); 4101 drv = reopen_state->bs->drv; 4102 4103 /* This function and each driver's bdrv_reopen_prepare() remove 4104 * entries from reopen_state->options as they are processed, so 4105 * we need to make a copy of the original QDict. */ 4106 orig_reopen_opts = qdict_clone_shallow(reopen_state->options); 4107 4108 /* Process generic block layer options */ 4109 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 4110 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) { 4111 ret = -EINVAL; 4112 goto error; 4113 } 4114 4115 /* This was already called in bdrv_reopen_queue_child() so the flags 4116 * are up-to-date. This time we simply want to remove the options from 4117 * QemuOpts in order to indicate that they have been processed. */ 4118 old_flags = reopen_state->flags; 4119 update_flags_from_options(&reopen_state->flags, opts); 4120 assert(old_flags == reopen_state->flags); 4121 4122 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD); 4123 if (discard != NULL) { 4124 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) { 4125 error_setg(errp, "Invalid discard option"); 4126 ret = -EINVAL; 4127 goto error; 4128 } 4129 } 4130 4131 reopen_state->detect_zeroes = 4132 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err); 4133 if (local_err) { 4134 error_propagate(errp, local_err); 4135 ret = -EINVAL; 4136 goto error; 4137 } 4138 4139 /* All other options (including node-name and driver) must be unchanged. 4140 * Put them back into the QDict, so that they are checked at the end 4141 * of this function. */ 4142 qemu_opts_to_qdict(opts, reopen_state->options); 4143 4144 /* If we are to stay read-only, do not allow permission change 4145 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is 4146 * not set, or if the BDS still has copy_on_read enabled */ 4147 read_only = !(reopen_state->flags & BDRV_O_RDWR); 4148 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err); 4149 if (local_err) { 4150 error_propagate(errp, local_err); 4151 goto error; 4152 } 4153 4154 /* Calculate required permissions after reopening */ 4155 bdrv_reopen_perm(queue, reopen_state->bs, 4156 &reopen_state->perm, &reopen_state->shared_perm); 4157 4158 ret = bdrv_flush(reopen_state->bs); 4159 if (ret) { 4160 error_setg_errno(errp, -ret, "Error flushing drive"); 4161 goto error; 4162 } 4163 4164 if (drv->bdrv_reopen_prepare) { 4165 /* 4166 * If a driver-specific option is missing, it means that we 4167 * should reset it to its default value. 4168 * But not all options allow that, so we need to check it first. 4169 */ 4170 ret = bdrv_reset_options_allowed(reopen_state->bs, 4171 reopen_state->options, errp); 4172 if (ret) { 4173 goto error; 4174 } 4175 4176 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err); 4177 if (ret) { 4178 if (local_err != NULL) { 4179 error_propagate(errp, local_err); 4180 } else { 4181 bdrv_refresh_filename(reopen_state->bs); 4182 error_setg(errp, "failed while preparing to reopen image '%s'", 4183 reopen_state->bs->filename); 4184 } 4185 goto error; 4186 } 4187 } else { 4188 /* It is currently mandatory to have a bdrv_reopen_prepare() 4189 * handler for each supported drv. */ 4190 error_setg(errp, "Block format '%s' used by node '%s' " 4191 "does not support reopening files", drv->format_name, 4192 bdrv_get_device_or_node_name(reopen_state->bs)); 4193 ret = -1; 4194 goto error; 4195 } 4196 4197 drv_prepared = true; 4198 4199 /* 4200 * We must provide the 'backing' option if the BDS has a backing 4201 * file or if the image file has a backing file name as part of 4202 * its metadata. Otherwise the 'backing' option can be omitted. 4203 */ 4204 if (drv->supports_backing && reopen_state->backing_missing && 4205 (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) { 4206 error_setg(errp, "backing is missing for '%s'", 4207 reopen_state->bs->node_name); 4208 ret = -EINVAL; 4209 goto error; 4210 } 4211 4212 /* 4213 * Allow changing the 'backing' option. The new value can be 4214 * either a reference to an existing node (using its node name) 4215 * or NULL to simply detach the current backing file. 4216 */ 4217 ret = bdrv_reopen_parse_backing(reopen_state, errp); 4218 if (ret < 0) { 4219 goto error; 4220 } 4221 qdict_del(reopen_state->options, "backing"); 4222 4223 /* Options that are not handled are only okay if they are unchanged 4224 * compared to the old state. It is expected that some options are only 4225 * used for the initial open, but not reopen (e.g. filename) */ 4226 if (qdict_size(reopen_state->options)) { 4227 const QDictEntry *entry = qdict_first(reopen_state->options); 4228 4229 do { 4230 QObject *new = entry->value; 4231 QObject *old = qdict_get(reopen_state->bs->options, entry->key); 4232 4233 /* Allow child references (child_name=node_name) as long as they 4234 * point to the current child (i.e. everything stays the same). */ 4235 if (qobject_type(new) == QTYPE_QSTRING) { 4236 BdrvChild *child; 4237 QLIST_FOREACH(child, &reopen_state->bs->children, next) { 4238 if (!strcmp(child->name, entry->key)) { 4239 break; 4240 } 4241 } 4242 4243 if (child) { 4244 if (!strcmp(child->bs->node_name, 4245 qstring_get_str(qobject_to(QString, new)))) { 4246 continue; /* Found child with this name, skip option */ 4247 } 4248 } 4249 } 4250 4251 /* 4252 * TODO: When using -drive to specify blockdev options, all values 4253 * will be strings; however, when using -blockdev, blockdev-add or 4254 * filenames using the json:{} pseudo-protocol, they will be 4255 * correctly typed. 4256 * In contrast, reopening options are (currently) always strings 4257 * (because you can only specify them through qemu-io; all other 4258 * callers do not specify any options). 4259 * Therefore, when using anything other than -drive to create a BDS, 4260 * this cannot detect non-string options as unchanged, because 4261 * qobject_is_equal() always returns false for objects of different 4262 * type. In the future, this should be remedied by correctly typing 4263 * all options. For now, this is not too big of an issue because 4264 * the user can simply omit options which cannot be changed anyway, 4265 * so they will stay unchanged. 4266 */ 4267 if (!qobject_is_equal(new, old)) { 4268 error_setg(errp, "Cannot change the option '%s'", entry->key); 4269 ret = -EINVAL; 4270 goto error; 4271 } 4272 } while ((entry = qdict_next(reopen_state->options, entry))); 4273 } 4274 4275 ret = 0; 4276 4277 /* Restore the original reopen_state->options QDict */ 4278 qobject_unref(reopen_state->options); 4279 reopen_state->options = qobject_ref(orig_reopen_opts); 4280 4281 error: 4282 if (ret < 0 && drv_prepared) { 4283 /* drv->bdrv_reopen_prepare() has succeeded, so we need to 4284 * call drv->bdrv_reopen_abort() before signaling an error 4285 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort() 4286 * when the respective bdrv_reopen_prepare() has failed) */ 4287 if (drv->bdrv_reopen_abort) { 4288 drv->bdrv_reopen_abort(reopen_state); 4289 } 4290 } 4291 qemu_opts_del(opts); 4292 qobject_unref(orig_reopen_opts); 4293 g_free(discard); 4294 return ret; 4295 } 4296 4297 /* 4298 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and 4299 * makes them final by swapping the staging BlockDriverState contents into 4300 * the active BlockDriverState contents. 4301 */ 4302 void bdrv_reopen_commit(BDRVReopenState *reopen_state) 4303 { 4304 BlockDriver *drv; 4305 BlockDriverState *bs; 4306 BdrvChild *child; 4307 4308 assert(reopen_state != NULL); 4309 bs = reopen_state->bs; 4310 drv = bs->drv; 4311 assert(drv != NULL); 4312 4313 /* If there are any driver level actions to take */ 4314 if (drv->bdrv_reopen_commit) { 4315 drv->bdrv_reopen_commit(reopen_state); 4316 } 4317 4318 /* set BDS specific flags now */ 4319 qobject_unref(bs->explicit_options); 4320 qobject_unref(bs->options); 4321 4322 bs->explicit_options = reopen_state->explicit_options; 4323 bs->options = reopen_state->options; 4324 bs->open_flags = reopen_state->flags; 4325 bs->read_only = !(reopen_state->flags & BDRV_O_RDWR); 4326 bs->detect_zeroes = reopen_state->detect_zeroes; 4327 4328 if (reopen_state->replace_backing_bs) { 4329 qdict_del(bs->explicit_options, "backing"); 4330 qdict_del(bs->options, "backing"); 4331 } 4332 4333 /* Remove child references from bs->options and bs->explicit_options. 4334 * Child options were already removed in bdrv_reopen_queue_child() */ 4335 QLIST_FOREACH(child, &bs->children, next) { 4336 qdict_del(bs->explicit_options, child->name); 4337 qdict_del(bs->options, child->name); 4338 } 4339 4340 /* 4341 * Change the backing file if a new one was specified. We do this 4342 * after updating bs->options, so bdrv_refresh_filename() (called 4343 * from bdrv_set_backing_hd()) has the new values. 4344 */ 4345 if (reopen_state->replace_backing_bs) { 4346 BlockDriverState *old_backing_bs = child_bs(bs->backing); 4347 assert(!old_backing_bs || !old_backing_bs->implicit); 4348 /* Abort the permission update on the backing bs we're detaching */ 4349 if (old_backing_bs) { 4350 bdrv_abort_perm_update(old_backing_bs); 4351 } 4352 bdrv_set_backing_hd(bs, reopen_state->new_backing_bs, &error_abort); 4353 } 4354 4355 bdrv_refresh_limits(bs, NULL); 4356 } 4357 4358 /* 4359 * Abort the reopen, and delete and free the staged changes in 4360 * reopen_state 4361 */ 4362 void bdrv_reopen_abort(BDRVReopenState *reopen_state) 4363 { 4364 BlockDriver *drv; 4365 4366 assert(reopen_state != NULL); 4367 drv = reopen_state->bs->drv; 4368 assert(drv != NULL); 4369 4370 if (drv->bdrv_reopen_abort) { 4371 drv->bdrv_reopen_abort(reopen_state); 4372 } 4373 } 4374 4375 4376 static void bdrv_close(BlockDriverState *bs) 4377 { 4378 BdrvAioNotifier *ban, *ban_next; 4379 BdrvChild *child, *next; 4380 4381 assert(!bs->refcnt); 4382 4383 bdrv_drained_begin(bs); /* complete I/O */ 4384 bdrv_flush(bs); 4385 bdrv_drain(bs); /* in case flush left pending I/O */ 4386 4387 if (bs->drv) { 4388 if (bs->drv->bdrv_close) { 4389 /* Must unfreeze all children, so bdrv_unref_child() works */ 4390 bs->drv->bdrv_close(bs); 4391 } 4392 bs->drv = NULL; 4393 } 4394 4395 QLIST_FOREACH_SAFE(child, &bs->children, next, next) { 4396 bdrv_unref_child(bs, child); 4397 } 4398 4399 bs->backing = NULL; 4400 bs->file = NULL; 4401 g_free(bs->opaque); 4402 bs->opaque = NULL; 4403 qatomic_set(&bs->copy_on_read, 0); 4404 bs->backing_file[0] = '\0'; 4405 bs->backing_format[0] = '\0'; 4406 bs->total_sectors = 0; 4407 bs->encrypted = false; 4408 bs->sg = false; 4409 qobject_unref(bs->options); 4410 qobject_unref(bs->explicit_options); 4411 bs->options = NULL; 4412 bs->explicit_options = NULL; 4413 qobject_unref(bs->full_open_options); 4414 bs->full_open_options = NULL; 4415 4416 bdrv_release_named_dirty_bitmaps(bs); 4417 assert(QLIST_EMPTY(&bs->dirty_bitmaps)); 4418 4419 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 4420 g_free(ban); 4421 } 4422 QLIST_INIT(&bs->aio_notifiers); 4423 bdrv_drained_end(bs); 4424 4425 /* 4426 * If we're still inside some bdrv_drain_all_begin()/end() sections, end 4427 * them now since this BDS won't exist anymore when bdrv_drain_all_end() 4428 * gets called. 4429 */ 4430 if (bs->quiesce_counter) { 4431 bdrv_drain_all_end_quiesce(bs); 4432 } 4433 } 4434 4435 void bdrv_close_all(void) 4436 { 4437 assert(job_next(NULL) == NULL); 4438 blk_exp_close_all(); 4439 4440 /* Drop references from requests still in flight, such as canceled block 4441 * jobs whose AIO context has not been polled yet */ 4442 bdrv_drain_all(); 4443 4444 blk_remove_all_bs(); 4445 blockdev_close_all_bdrv_states(); 4446 4447 assert(QTAILQ_EMPTY(&all_bdrv_states)); 4448 } 4449 4450 static bool should_update_child(BdrvChild *c, BlockDriverState *to) 4451 { 4452 GQueue *queue; 4453 GHashTable *found; 4454 bool ret; 4455 4456 if (c->klass->stay_at_node) { 4457 return false; 4458 } 4459 4460 /* If the child @c belongs to the BDS @to, replacing the current 4461 * c->bs by @to would mean to create a loop. 4462 * 4463 * Such a case occurs when appending a BDS to a backing chain. 4464 * For instance, imagine the following chain: 4465 * 4466 * guest device -> node A -> further backing chain... 4467 * 4468 * Now we create a new BDS B which we want to put on top of this 4469 * chain, so we first attach A as its backing node: 4470 * 4471 * node B 4472 * | 4473 * v 4474 * guest device -> node A -> further backing chain... 4475 * 4476 * Finally we want to replace A by B. When doing that, we want to 4477 * replace all pointers to A by pointers to B -- except for the 4478 * pointer from B because (1) that would create a loop, and (2) 4479 * that pointer should simply stay intact: 4480 * 4481 * guest device -> node B 4482 * | 4483 * v 4484 * node A -> further backing chain... 4485 * 4486 * In general, when replacing a node A (c->bs) by a node B (@to), 4487 * if A is a child of B, that means we cannot replace A by B there 4488 * because that would create a loop. Silently detaching A from B 4489 * is also not really an option. So overall just leaving A in 4490 * place there is the most sensible choice. 4491 * 4492 * We would also create a loop in any cases where @c is only 4493 * indirectly referenced by @to. Prevent this by returning false 4494 * if @c is found (by breadth-first search) anywhere in the whole 4495 * subtree of @to. 4496 */ 4497 4498 ret = true; 4499 found = g_hash_table_new(NULL, NULL); 4500 g_hash_table_add(found, to); 4501 queue = g_queue_new(); 4502 g_queue_push_tail(queue, to); 4503 4504 while (!g_queue_is_empty(queue)) { 4505 BlockDriverState *v = g_queue_pop_head(queue); 4506 BdrvChild *c2; 4507 4508 QLIST_FOREACH(c2, &v->children, next) { 4509 if (c2 == c) { 4510 ret = false; 4511 break; 4512 } 4513 4514 if (g_hash_table_contains(found, c2->bs)) { 4515 continue; 4516 } 4517 4518 g_queue_push_tail(queue, c2->bs); 4519 g_hash_table_add(found, c2->bs); 4520 } 4521 } 4522 4523 g_queue_free(queue); 4524 g_hash_table_destroy(found); 4525 4526 return ret; 4527 } 4528 4529 /* 4530 * With auto_skip=true bdrv_replace_node_common skips updating from parents 4531 * if it creates a parent-child relation loop or if parent is block-job. 4532 * 4533 * With auto_skip=false the error is returned if from has a parent which should 4534 * not be updated. 4535 */ 4536 static void bdrv_replace_node_common(BlockDriverState *from, 4537 BlockDriverState *to, 4538 bool auto_skip, Error **errp) 4539 { 4540 BdrvChild *c, *next; 4541 GSList *list = NULL, *p; 4542 uint64_t perm = 0, shared = BLK_PERM_ALL; 4543 int ret; 4544 4545 /* Make sure that @from doesn't go away until we have successfully attached 4546 * all of its parents to @to. */ 4547 bdrv_ref(from); 4548 4549 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 4550 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to)); 4551 bdrv_drained_begin(from); 4552 4553 /* Put all parents into @list and calculate their cumulative permissions */ 4554 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { 4555 assert(c->bs == from); 4556 if (!should_update_child(c, to)) { 4557 if (auto_skip) { 4558 continue; 4559 } 4560 error_setg(errp, "Should not change '%s' link to '%s'", 4561 c->name, from->node_name); 4562 goto out; 4563 } 4564 if (c->frozen) { 4565 error_setg(errp, "Cannot change '%s' link to '%s'", 4566 c->name, from->node_name); 4567 goto out; 4568 } 4569 list = g_slist_prepend(list, c); 4570 perm |= c->perm; 4571 shared &= c->shared_perm; 4572 } 4573 4574 /* Check whether the required permissions can be granted on @to, ignoring 4575 * all BdrvChild in @list so that they can't block themselves. */ 4576 ret = bdrv_check_update_perm(to, NULL, perm, shared, list, errp); 4577 if (ret < 0) { 4578 bdrv_abort_perm_update(to); 4579 goto out; 4580 } 4581 4582 /* Now actually perform the change. We performed the permission check for 4583 * all elements of @list at once, so set the permissions all at once at the 4584 * very end. */ 4585 for (p = list; p != NULL; p = p->next) { 4586 c = p->data; 4587 4588 bdrv_ref(to); 4589 bdrv_replace_child_noperm(c, to); 4590 bdrv_unref(from); 4591 } 4592 4593 bdrv_set_perm(to); 4594 4595 out: 4596 g_slist_free(list); 4597 bdrv_drained_end(from); 4598 bdrv_unref(from); 4599 } 4600 4601 void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, 4602 Error **errp) 4603 { 4604 return bdrv_replace_node_common(from, to, true, errp); 4605 } 4606 4607 /* 4608 * Add new bs contents at the top of an image chain while the chain is 4609 * live, while keeping required fields on the top layer. 4610 * 4611 * This will modify the BlockDriverState fields, and swap contents 4612 * between bs_new and bs_top. Both bs_new and bs_top are modified. 4613 * 4614 * bs_new must not be attached to a BlockBackend. 4615 * 4616 * This function does not create any image files. 4617 * 4618 * bdrv_append() takes ownership of a bs_new reference and unrefs it because 4619 * that's what the callers commonly need. bs_new will be referenced by the old 4620 * parents of bs_top after bdrv_append() returns. If the caller needs to keep a 4621 * reference of its own, it must call bdrv_ref(). 4622 */ 4623 void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, 4624 Error **errp) 4625 { 4626 Error *local_err = NULL; 4627 4628 bdrv_set_backing_hd(bs_new, bs_top, &local_err); 4629 if (local_err) { 4630 error_propagate(errp, local_err); 4631 goto out; 4632 } 4633 4634 bdrv_replace_node(bs_top, bs_new, &local_err); 4635 if (local_err) { 4636 error_propagate(errp, local_err); 4637 bdrv_set_backing_hd(bs_new, NULL, &error_abort); 4638 goto out; 4639 } 4640 4641 /* bs_new is now referenced by its new parents, we don't need the 4642 * additional reference any more. */ 4643 out: 4644 bdrv_unref(bs_new); 4645 } 4646 4647 static void bdrv_delete(BlockDriverState *bs) 4648 { 4649 assert(bdrv_op_blocker_is_empty(bs)); 4650 assert(!bs->refcnt); 4651 4652 /* remove from list, if necessary */ 4653 if (bs->node_name[0] != '\0') { 4654 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list); 4655 } 4656 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list); 4657 4658 bdrv_close(bs); 4659 4660 g_free(bs); 4661 } 4662 4663 BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *node_options, 4664 int flags, Error **errp) 4665 { 4666 BlockDriverState *new_node_bs; 4667 Error *local_err = NULL; 4668 4669 new_node_bs = bdrv_open(NULL, NULL, node_options, flags, errp); 4670 if (new_node_bs == NULL) { 4671 error_prepend(errp, "Could not create node: "); 4672 return NULL; 4673 } 4674 4675 bdrv_drained_begin(bs); 4676 bdrv_replace_node(bs, new_node_bs, &local_err); 4677 bdrv_drained_end(bs); 4678 4679 if (local_err) { 4680 bdrv_unref(new_node_bs); 4681 error_propagate(errp, local_err); 4682 return NULL; 4683 } 4684 4685 return new_node_bs; 4686 } 4687 4688 /* 4689 * Run consistency checks on an image 4690 * 4691 * Returns 0 if the check could be completed (it doesn't mean that the image is 4692 * free of errors) or -errno when an internal error occurred. The results of the 4693 * check are stored in res. 4694 */ 4695 int coroutine_fn bdrv_co_check(BlockDriverState *bs, 4696 BdrvCheckResult *res, BdrvCheckMode fix) 4697 { 4698 if (bs->drv == NULL) { 4699 return -ENOMEDIUM; 4700 } 4701 if (bs->drv->bdrv_co_check == NULL) { 4702 return -ENOTSUP; 4703 } 4704 4705 memset(res, 0, sizeof(*res)); 4706 return bs->drv->bdrv_co_check(bs, res, fix); 4707 } 4708 4709 /* 4710 * Return values: 4711 * 0 - success 4712 * -EINVAL - backing format specified, but no file 4713 * -ENOSPC - can't update the backing file because no space is left in the 4714 * image file header 4715 * -ENOTSUP - format driver doesn't support changing the backing file 4716 */ 4717 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file, 4718 const char *backing_fmt, bool warn) 4719 { 4720 BlockDriver *drv = bs->drv; 4721 int ret; 4722 4723 if (!drv) { 4724 return -ENOMEDIUM; 4725 } 4726 4727 /* Backing file format doesn't make sense without a backing file */ 4728 if (backing_fmt && !backing_file) { 4729 return -EINVAL; 4730 } 4731 4732 if (warn && backing_file && !backing_fmt) { 4733 warn_report("Deprecated use of backing file without explicit " 4734 "backing format, use of this image requires " 4735 "potentially unsafe format probing"); 4736 } 4737 4738 if (drv->bdrv_change_backing_file != NULL) { 4739 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt); 4740 } else { 4741 ret = -ENOTSUP; 4742 } 4743 4744 if (ret == 0) { 4745 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: ""); 4746 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: ""); 4747 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 4748 backing_file ?: ""); 4749 } 4750 return ret; 4751 } 4752 4753 /* 4754 * Finds the first non-filter node above bs in the chain between 4755 * active and bs. The returned node is either an immediate parent of 4756 * bs, or there are only filter nodes between the two. 4757 * 4758 * Returns NULL if bs is not found in active's image chain, 4759 * or if active == bs. 4760 * 4761 * Returns the bottommost base image if bs == NULL. 4762 */ 4763 BlockDriverState *bdrv_find_overlay(BlockDriverState *active, 4764 BlockDriverState *bs) 4765 { 4766 bs = bdrv_skip_filters(bs); 4767 active = bdrv_skip_filters(active); 4768 4769 while (active) { 4770 BlockDriverState *next = bdrv_backing_chain_next(active); 4771 if (bs == next) { 4772 return active; 4773 } 4774 active = next; 4775 } 4776 4777 return NULL; 4778 } 4779 4780 /* Given a BDS, searches for the base layer. */ 4781 BlockDriverState *bdrv_find_base(BlockDriverState *bs) 4782 { 4783 return bdrv_find_overlay(bs, NULL); 4784 } 4785 4786 /* 4787 * Return true if at least one of the COW (backing) and filter links 4788 * between @bs and @base is frozen. @errp is set if that's the case. 4789 * @base must be reachable from @bs, or NULL. 4790 */ 4791 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base, 4792 Error **errp) 4793 { 4794 BlockDriverState *i; 4795 BdrvChild *child; 4796 4797 for (i = bs; i != base; i = child_bs(child)) { 4798 child = bdrv_filter_or_cow_child(i); 4799 4800 if (child && child->frozen) { 4801 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'", 4802 child->name, i->node_name, child->bs->node_name); 4803 return true; 4804 } 4805 } 4806 4807 return false; 4808 } 4809 4810 /* 4811 * Freeze all COW (backing) and filter links between @bs and @base. 4812 * If any of the links is already frozen the operation is aborted and 4813 * none of the links are modified. 4814 * @base must be reachable from @bs, or NULL. 4815 * Returns 0 on success. On failure returns < 0 and sets @errp. 4816 */ 4817 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base, 4818 Error **errp) 4819 { 4820 BlockDriverState *i; 4821 BdrvChild *child; 4822 4823 if (bdrv_is_backing_chain_frozen(bs, base, errp)) { 4824 return -EPERM; 4825 } 4826 4827 for (i = bs; i != base; i = child_bs(child)) { 4828 child = bdrv_filter_or_cow_child(i); 4829 if (child && child->bs->never_freeze) { 4830 error_setg(errp, "Cannot freeze '%s' link to '%s'", 4831 child->name, child->bs->node_name); 4832 return -EPERM; 4833 } 4834 } 4835 4836 for (i = bs; i != base; i = child_bs(child)) { 4837 child = bdrv_filter_or_cow_child(i); 4838 if (child) { 4839 child->frozen = true; 4840 } 4841 } 4842 4843 return 0; 4844 } 4845 4846 /* 4847 * Unfreeze all COW (backing) and filter links between @bs and @base. 4848 * The caller must ensure that all links are frozen before using this 4849 * function. 4850 * @base must be reachable from @bs, or NULL. 4851 */ 4852 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base) 4853 { 4854 BlockDriverState *i; 4855 BdrvChild *child; 4856 4857 for (i = bs; i != base; i = child_bs(child)) { 4858 child = bdrv_filter_or_cow_child(i); 4859 if (child) { 4860 assert(child->frozen); 4861 child->frozen = false; 4862 } 4863 } 4864 } 4865 4866 /* 4867 * Drops images above 'base' up to and including 'top', and sets the image 4868 * above 'top' to have base as its backing file. 4869 * 4870 * Requires that the overlay to 'top' is opened r/w, so that the backing file 4871 * information in 'bs' can be properly updated. 4872 * 4873 * E.g., this will convert the following chain: 4874 * bottom <- base <- intermediate <- top <- active 4875 * 4876 * to 4877 * 4878 * bottom <- base <- active 4879 * 4880 * It is allowed for bottom==base, in which case it converts: 4881 * 4882 * base <- intermediate <- top <- active 4883 * 4884 * to 4885 * 4886 * base <- active 4887 * 4888 * If backing_file_str is non-NULL, it will be used when modifying top's 4889 * overlay image metadata. 4890 * 4891 * Error conditions: 4892 * if active == top, that is considered an error 4893 * 4894 */ 4895 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, 4896 const char *backing_file_str) 4897 { 4898 BlockDriverState *explicit_top = top; 4899 bool update_inherits_from; 4900 BdrvChild *c; 4901 Error *local_err = NULL; 4902 int ret = -EIO; 4903 g_autoptr(GSList) updated_children = NULL; 4904 GSList *p; 4905 4906 bdrv_ref(top); 4907 bdrv_subtree_drained_begin(top); 4908 4909 if (!top->drv || !base->drv) { 4910 goto exit; 4911 } 4912 4913 /* Make sure that base is in the backing chain of top */ 4914 if (!bdrv_chain_contains(top, base)) { 4915 goto exit; 4916 } 4917 4918 /* If 'base' recursively inherits from 'top' then we should set 4919 * base->inherits_from to top->inherits_from after 'top' and all 4920 * other intermediate nodes have been dropped. 4921 * If 'top' is an implicit node (e.g. "commit_top") we should skip 4922 * it because no one inherits from it. We use explicit_top for that. */ 4923 explicit_top = bdrv_skip_implicit_filters(explicit_top); 4924 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top); 4925 4926 /* success - we can delete the intermediate states, and link top->base */ 4927 /* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once 4928 * we've figured out how they should work. */ 4929 if (!backing_file_str) { 4930 bdrv_refresh_filename(base); 4931 backing_file_str = base->filename; 4932 } 4933 4934 QLIST_FOREACH(c, &top->parents, next_parent) { 4935 updated_children = g_slist_prepend(updated_children, c); 4936 } 4937 4938 bdrv_replace_node_common(top, base, false, &local_err); 4939 if (local_err) { 4940 error_report_err(local_err); 4941 goto exit; 4942 } 4943 4944 for (p = updated_children; p; p = p->next) { 4945 c = p->data; 4946 4947 if (c->klass->update_filename) { 4948 ret = c->klass->update_filename(c, base, backing_file_str, 4949 &local_err); 4950 if (ret < 0) { 4951 /* 4952 * TODO: Actually, we want to rollback all previous iterations 4953 * of this loop, and (which is almost impossible) previous 4954 * bdrv_replace_node()... 4955 * 4956 * Note, that c->klass->update_filename may lead to permission 4957 * update, so it's a bad idea to call it inside permission 4958 * update transaction of bdrv_replace_node. 4959 */ 4960 error_report_err(local_err); 4961 goto exit; 4962 } 4963 } 4964 } 4965 4966 if (update_inherits_from) { 4967 base->inherits_from = explicit_top->inherits_from; 4968 } 4969 4970 ret = 0; 4971 exit: 4972 bdrv_subtree_drained_end(top); 4973 bdrv_unref(top); 4974 return ret; 4975 } 4976 4977 /** 4978 * Implementation of BlockDriver.bdrv_get_allocated_file_size() that 4979 * sums the size of all data-bearing children. (This excludes backing 4980 * children.) 4981 */ 4982 static int64_t bdrv_sum_allocated_file_size(BlockDriverState *bs) 4983 { 4984 BdrvChild *child; 4985 int64_t child_size, sum = 0; 4986 4987 QLIST_FOREACH(child, &bs->children, next) { 4988 if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | 4989 BDRV_CHILD_FILTERED)) 4990 { 4991 child_size = bdrv_get_allocated_file_size(child->bs); 4992 if (child_size < 0) { 4993 return child_size; 4994 } 4995 sum += child_size; 4996 } 4997 } 4998 4999 return sum; 5000 } 5001 5002 /** 5003 * Length of a allocated file in bytes. Sparse files are counted by actual 5004 * allocated space. Return < 0 if error or unknown. 5005 */ 5006 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs) 5007 { 5008 BlockDriver *drv = bs->drv; 5009 if (!drv) { 5010 return -ENOMEDIUM; 5011 } 5012 if (drv->bdrv_get_allocated_file_size) { 5013 return drv->bdrv_get_allocated_file_size(bs); 5014 } 5015 5016 if (drv->bdrv_file_open) { 5017 /* 5018 * Protocol drivers default to -ENOTSUP (most of their data is 5019 * not stored in any of their children (if they even have any), 5020 * so there is no generic way to figure it out). 5021 */ 5022 return -ENOTSUP; 5023 } else if (drv->is_filter) { 5024 /* Filter drivers default to the size of their filtered child */ 5025 return bdrv_get_allocated_file_size(bdrv_filter_bs(bs)); 5026 } else { 5027 /* Other drivers default to summing their children's sizes */ 5028 return bdrv_sum_allocated_file_size(bs); 5029 } 5030 } 5031 5032 /* 5033 * bdrv_measure: 5034 * @drv: Format driver 5035 * @opts: Creation options for new image 5036 * @in_bs: Existing image containing data for new image (may be NULL) 5037 * @errp: Error object 5038 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo()) 5039 * or NULL on error 5040 * 5041 * Calculate file size required to create a new image. 5042 * 5043 * If @in_bs is given then space for allocated clusters and zero clusters 5044 * from that image are included in the calculation. If @opts contains a 5045 * backing file that is shared by @in_bs then backing clusters may be omitted 5046 * from the calculation. 5047 * 5048 * If @in_bs is NULL then the calculation includes no allocated clusters 5049 * unless a preallocation option is given in @opts. 5050 * 5051 * Note that @in_bs may use a different BlockDriver from @drv. 5052 * 5053 * If an error occurs the @errp pointer is set. 5054 */ 5055 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, 5056 BlockDriverState *in_bs, Error **errp) 5057 { 5058 if (!drv->bdrv_measure) { 5059 error_setg(errp, "Block driver '%s' does not support size measurement", 5060 drv->format_name); 5061 return NULL; 5062 } 5063 5064 return drv->bdrv_measure(opts, in_bs, errp); 5065 } 5066 5067 /** 5068 * Return number of sectors on success, -errno on error. 5069 */ 5070 int64_t bdrv_nb_sectors(BlockDriverState *bs) 5071 { 5072 BlockDriver *drv = bs->drv; 5073 5074 if (!drv) 5075 return -ENOMEDIUM; 5076 5077 if (drv->has_variable_length) { 5078 int ret = refresh_total_sectors(bs, bs->total_sectors); 5079 if (ret < 0) { 5080 return ret; 5081 } 5082 } 5083 return bs->total_sectors; 5084 } 5085 5086 /** 5087 * Return length in bytes on success, -errno on error. 5088 * The length is always a multiple of BDRV_SECTOR_SIZE. 5089 */ 5090 int64_t bdrv_getlength(BlockDriverState *bs) 5091 { 5092 int64_t ret = bdrv_nb_sectors(bs); 5093 5094 if (ret < 0) { 5095 return ret; 5096 } 5097 if (ret > INT64_MAX / BDRV_SECTOR_SIZE) { 5098 return -EFBIG; 5099 } 5100 return ret * BDRV_SECTOR_SIZE; 5101 } 5102 5103 /* return 0 as number of sectors if no device present or error */ 5104 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr) 5105 { 5106 int64_t nb_sectors = bdrv_nb_sectors(bs); 5107 5108 *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors; 5109 } 5110 5111 bool bdrv_is_sg(BlockDriverState *bs) 5112 { 5113 return bs->sg; 5114 } 5115 5116 /** 5117 * Return whether the given node supports compressed writes. 5118 */ 5119 bool bdrv_supports_compressed_writes(BlockDriverState *bs) 5120 { 5121 BlockDriverState *filtered; 5122 5123 if (!bs->drv || !block_driver_can_compress(bs->drv)) { 5124 return false; 5125 } 5126 5127 filtered = bdrv_filter_bs(bs); 5128 if (filtered) { 5129 /* 5130 * Filters can only forward compressed writes, so we have to 5131 * check the child. 5132 */ 5133 return bdrv_supports_compressed_writes(filtered); 5134 } 5135 5136 return true; 5137 } 5138 5139 const char *bdrv_get_format_name(BlockDriverState *bs) 5140 { 5141 return bs->drv ? bs->drv->format_name : NULL; 5142 } 5143 5144 static int qsort_strcmp(const void *a, const void *b) 5145 { 5146 return strcmp(*(char *const *)a, *(char *const *)b); 5147 } 5148 5149 void bdrv_iterate_format(void (*it)(void *opaque, const char *name), 5150 void *opaque, bool read_only) 5151 { 5152 BlockDriver *drv; 5153 int count = 0; 5154 int i; 5155 const char **formats = NULL; 5156 5157 QLIST_FOREACH(drv, &bdrv_drivers, list) { 5158 if (drv->format_name) { 5159 bool found = false; 5160 int i = count; 5161 5162 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) { 5163 continue; 5164 } 5165 5166 while (formats && i && !found) { 5167 found = !strcmp(formats[--i], drv->format_name); 5168 } 5169 5170 if (!found) { 5171 formats = g_renew(const char *, formats, count + 1); 5172 formats[count++] = drv->format_name; 5173 } 5174 } 5175 } 5176 5177 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) { 5178 const char *format_name = block_driver_modules[i].format_name; 5179 5180 if (format_name) { 5181 bool found = false; 5182 int j = count; 5183 5184 if (use_bdrv_whitelist && 5185 !bdrv_format_is_whitelisted(format_name, read_only)) { 5186 continue; 5187 } 5188 5189 while (formats && j && !found) { 5190 found = !strcmp(formats[--j], format_name); 5191 } 5192 5193 if (!found) { 5194 formats = g_renew(const char *, formats, count + 1); 5195 formats[count++] = format_name; 5196 } 5197 } 5198 } 5199 5200 qsort(formats, count, sizeof(formats[0]), qsort_strcmp); 5201 5202 for (i = 0; i < count; i++) { 5203 it(opaque, formats[i]); 5204 } 5205 5206 g_free(formats); 5207 } 5208 5209 /* This function is to find a node in the bs graph */ 5210 BlockDriverState *bdrv_find_node(const char *node_name) 5211 { 5212 BlockDriverState *bs; 5213 5214 assert(node_name); 5215 5216 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 5217 if (!strcmp(node_name, bs->node_name)) { 5218 return bs; 5219 } 5220 } 5221 return NULL; 5222 } 5223 5224 /* Put this QMP function here so it can access the static graph_bdrv_states. */ 5225 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat, 5226 Error **errp) 5227 { 5228 BlockDeviceInfoList *list; 5229 BlockDriverState *bs; 5230 5231 list = NULL; 5232 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 5233 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp); 5234 if (!info) { 5235 qapi_free_BlockDeviceInfoList(list); 5236 return NULL; 5237 } 5238 QAPI_LIST_PREPEND(list, info); 5239 } 5240 5241 return list; 5242 } 5243 5244 typedef struct XDbgBlockGraphConstructor { 5245 XDbgBlockGraph *graph; 5246 GHashTable *graph_nodes; 5247 } XDbgBlockGraphConstructor; 5248 5249 static XDbgBlockGraphConstructor *xdbg_graph_new(void) 5250 { 5251 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1); 5252 5253 gr->graph = g_new0(XDbgBlockGraph, 1); 5254 gr->graph_nodes = g_hash_table_new(NULL, NULL); 5255 5256 return gr; 5257 } 5258 5259 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr) 5260 { 5261 XDbgBlockGraph *graph = gr->graph; 5262 5263 g_hash_table_destroy(gr->graph_nodes); 5264 g_free(gr); 5265 5266 return graph; 5267 } 5268 5269 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node) 5270 { 5271 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node); 5272 5273 if (ret != 0) { 5274 return ret; 5275 } 5276 5277 /* 5278 * Start counting from 1, not 0, because 0 interferes with not-found (NULL) 5279 * answer of g_hash_table_lookup. 5280 */ 5281 ret = g_hash_table_size(gr->graph_nodes) + 1; 5282 g_hash_table_insert(gr->graph_nodes, node, (void *)ret); 5283 5284 return ret; 5285 } 5286 5287 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node, 5288 XDbgBlockGraphNodeType type, const char *name) 5289 { 5290 XDbgBlockGraphNode *n; 5291 5292 n = g_new0(XDbgBlockGraphNode, 1); 5293 5294 n->id = xdbg_graph_node_num(gr, node); 5295 n->type = type; 5296 n->name = g_strdup(name); 5297 5298 QAPI_LIST_PREPEND(gr->graph->nodes, n); 5299 } 5300 5301 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent, 5302 const BdrvChild *child) 5303 { 5304 BlockPermission qapi_perm; 5305 XDbgBlockGraphEdge *edge; 5306 5307 edge = g_new0(XDbgBlockGraphEdge, 1); 5308 5309 edge->parent = xdbg_graph_node_num(gr, parent); 5310 edge->child = xdbg_graph_node_num(gr, child->bs); 5311 edge->name = g_strdup(child->name); 5312 5313 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) { 5314 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm); 5315 5316 if (flag & child->perm) { 5317 QAPI_LIST_PREPEND(edge->perm, qapi_perm); 5318 } 5319 if (flag & child->shared_perm) { 5320 QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm); 5321 } 5322 } 5323 5324 QAPI_LIST_PREPEND(gr->graph->edges, edge); 5325 } 5326 5327 5328 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp) 5329 { 5330 BlockBackend *blk; 5331 BlockJob *job; 5332 BlockDriverState *bs; 5333 BdrvChild *child; 5334 XDbgBlockGraphConstructor *gr = xdbg_graph_new(); 5335 5336 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) { 5337 char *allocated_name = NULL; 5338 const char *name = blk_name(blk); 5339 5340 if (!*name) { 5341 name = allocated_name = blk_get_attached_dev_id(blk); 5342 } 5343 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND, 5344 name); 5345 g_free(allocated_name); 5346 if (blk_root(blk)) { 5347 xdbg_graph_add_edge(gr, blk, blk_root(blk)); 5348 } 5349 } 5350 5351 for (job = block_job_next(NULL); job; job = block_job_next(job)) { 5352 GSList *el; 5353 5354 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB, 5355 job->job.id); 5356 for (el = job->nodes; el; el = el->next) { 5357 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data); 5358 } 5359 } 5360 5361 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 5362 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER, 5363 bs->node_name); 5364 QLIST_FOREACH(child, &bs->children, next) { 5365 xdbg_graph_add_edge(gr, bs, child); 5366 } 5367 } 5368 5369 return xdbg_graph_finalize(gr); 5370 } 5371 5372 BlockDriverState *bdrv_lookup_bs(const char *device, 5373 const char *node_name, 5374 Error **errp) 5375 { 5376 BlockBackend *blk; 5377 BlockDriverState *bs; 5378 5379 if (device) { 5380 blk = blk_by_name(device); 5381 5382 if (blk) { 5383 bs = blk_bs(blk); 5384 if (!bs) { 5385 error_setg(errp, "Device '%s' has no medium", device); 5386 } 5387 5388 return bs; 5389 } 5390 } 5391 5392 if (node_name) { 5393 bs = bdrv_find_node(node_name); 5394 5395 if (bs) { 5396 return bs; 5397 } 5398 } 5399 5400 error_setg(errp, "Cannot find device=%s nor node_name=%s", 5401 device ? device : "", 5402 node_name ? node_name : ""); 5403 return NULL; 5404 } 5405 5406 /* If 'base' is in the same chain as 'top', return true. Otherwise, 5407 * return false. If either argument is NULL, return false. */ 5408 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base) 5409 { 5410 while (top && top != base) { 5411 top = bdrv_filter_or_cow_bs(top); 5412 } 5413 5414 return top != NULL; 5415 } 5416 5417 BlockDriverState *bdrv_next_node(BlockDriverState *bs) 5418 { 5419 if (!bs) { 5420 return QTAILQ_FIRST(&graph_bdrv_states); 5421 } 5422 return QTAILQ_NEXT(bs, node_list); 5423 } 5424 5425 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs) 5426 { 5427 if (!bs) { 5428 return QTAILQ_FIRST(&all_bdrv_states); 5429 } 5430 return QTAILQ_NEXT(bs, bs_list); 5431 } 5432 5433 const char *bdrv_get_node_name(const BlockDriverState *bs) 5434 { 5435 return bs->node_name; 5436 } 5437 5438 const char *bdrv_get_parent_name(const BlockDriverState *bs) 5439 { 5440 BdrvChild *c; 5441 const char *name; 5442 5443 /* If multiple parents have a name, just pick the first one. */ 5444 QLIST_FOREACH(c, &bs->parents, next_parent) { 5445 if (c->klass->get_name) { 5446 name = c->klass->get_name(c); 5447 if (name && *name) { 5448 return name; 5449 } 5450 } 5451 } 5452 5453 return NULL; 5454 } 5455 5456 /* TODO check what callers really want: bs->node_name or blk_name() */ 5457 const char *bdrv_get_device_name(const BlockDriverState *bs) 5458 { 5459 return bdrv_get_parent_name(bs) ?: ""; 5460 } 5461 5462 /* This can be used to identify nodes that might not have a device 5463 * name associated. Since node and device names live in the same 5464 * namespace, the result is unambiguous. The exception is if both are 5465 * absent, then this returns an empty (non-null) string. */ 5466 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs) 5467 { 5468 return bdrv_get_parent_name(bs) ?: bs->node_name; 5469 } 5470 5471 int bdrv_get_flags(BlockDriverState *bs) 5472 { 5473 return bs->open_flags; 5474 } 5475 5476 int bdrv_has_zero_init_1(BlockDriverState *bs) 5477 { 5478 return 1; 5479 } 5480 5481 int bdrv_has_zero_init(BlockDriverState *bs) 5482 { 5483 BlockDriverState *filtered; 5484 5485 if (!bs->drv) { 5486 return 0; 5487 } 5488 5489 /* If BS is a copy on write image, it is initialized to 5490 the contents of the base image, which may not be zeroes. */ 5491 if (bdrv_cow_child(bs)) { 5492 return 0; 5493 } 5494 if (bs->drv->bdrv_has_zero_init) { 5495 return bs->drv->bdrv_has_zero_init(bs); 5496 } 5497 5498 filtered = bdrv_filter_bs(bs); 5499 if (filtered) { 5500 return bdrv_has_zero_init(filtered); 5501 } 5502 5503 /* safe default */ 5504 return 0; 5505 } 5506 5507 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs) 5508 { 5509 if (!(bs->open_flags & BDRV_O_UNMAP)) { 5510 return false; 5511 } 5512 5513 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP; 5514 } 5515 5516 void bdrv_get_backing_filename(BlockDriverState *bs, 5517 char *filename, int filename_size) 5518 { 5519 pstrcpy(filename, filename_size, bs->backing_file); 5520 } 5521 5522 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) 5523 { 5524 int ret; 5525 BlockDriver *drv = bs->drv; 5526 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */ 5527 if (!drv) { 5528 return -ENOMEDIUM; 5529 } 5530 if (!drv->bdrv_get_info) { 5531 BlockDriverState *filtered = bdrv_filter_bs(bs); 5532 if (filtered) { 5533 return bdrv_get_info(filtered, bdi); 5534 } 5535 return -ENOTSUP; 5536 } 5537 memset(bdi, 0, sizeof(*bdi)); 5538 ret = drv->bdrv_get_info(bs, bdi); 5539 if (ret < 0) { 5540 return ret; 5541 } 5542 5543 if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) { 5544 return -EINVAL; 5545 } 5546 5547 return 0; 5548 } 5549 5550 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, 5551 Error **errp) 5552 { 5553 BlockDriver *drv = bs->drv; 5554 if (drv && drv->bdrv_get_specific_info) { 5555 return drv->bdrv_get_specific_info(bs, errp); 5556 } 5557 return NULL; 5558 } 5559 5560 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs) 5561 { 5562 BlockDriver *drv = bs->drv; 5563 if (!drv || !drv->bdrv_get_specific_stats) { 5564 return NULL; 5565 } 5566 return drv->bdrv_get_specific_stats(bs); 5567 } 5568 5569 void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event) 5570 { 5571 if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) { 5572 return; 5573 } 5574 5575 bs->drv->bdrv_debug_event(bs, event); 5576 } 5577 5578 static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs) 5579 { 5580 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) { 5581 bs = bdrv_primary_bs(bs); 5582 } 5583 5584 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) { 5585 assert(bs->drv->bdrv_debug_remove_breakpoint); 5586 return bs; 5587 } 5588 5589 return NULL; 5590 } 5591 5592 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event, 5593 const char *tag) 5594 { 5595 bs = bdrv_find_debug_node(bs); 5596 if (bs) { 5597 return bs->drv->bdrv_debug_breakpoint(bs, event, tag); 5598 } 5599 5600 return -ENOTSUP; 5601 } 5602 5603 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag) 5604 { 5605 bs = bdrv_find_debug_node(bs); 5606 if (bs) { 5607 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag); 5608 } 5609 5610 return -ENOTSUP; 5611 } 5612 5613 int bdrv_debug_resume(BlockDriverState *bs, const char *tag) 5614 { 5615 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) { 5616 bs = bdrv_primary_bs(bs); 5617 } 5618 5619 if (bs && bs->drv && bs->drv->bdrv_debug_resume) { 5620 return bs->drv->bdrv_debug_resume(bs, tag); 5621 } 5622 5623 return -ENOTSUP; 5624 } 5625 5626 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag) 5627 { 5628 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) { 5629 bs = bdrv_primary_bs(bs); 5630 } 5631 5632 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) { 5633 return bs->drv->bdrv_debug_is_suspended(bs, tag); 5634 } 5635 5636 return false; 5637 } 5638 5639 /* backing_file can either be relative, or absolute, or a protocol. If it is 5640 * relative, it must be relative to the chain. So, passing in bs->filename 5641 * from a BDS as backing_file should not be done, as that may be relative to 5642 * the CWD rather than the chain. */ 5643 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, 5644 const char *backing_file) 5645 { 5646 char *filename_full = NULL; 5647 char *backing_file_full = NULL; 5648 char *filename_tmp = NULL; 5649 int is_protocol = 0; 5650 bool filenames_refreshed = false; 5651 BlockDriverState *curr_bs = NULL; 5652 BlockDriverState *retval = NULL; 5653 BlockDriverState *bs_below; 5654 5655 if (!bs || !bs->drv || !backing_file) { 5656 return NULL; 5657 } 5658 5659 filename_full = g_malloc(PATH_MAX); 5660 backing_file_full = g_malloc(PATH_MAX); 5661 5662 is_protocol = path_has_protocol(backing_file); 5663 5664 /* 5665 * Being largely a legacy function, skip any filters here 5666 * (because filters do not have normal filenames, so they cannot 5667 * match anyway; and allowing json:{} filenames is a bit out of 5668 * scope). 5669 */ 5670 for (curr_bs = bdrv_skip_filters(bs); 5671 bdrv_cow_child(curr_bs) != NULL; 5672 curr_bs = bs_below) 5673 { 5674 bs_below = bdrv_backing_chain_next(curr_bs); 5675 5676 if (bdrv_backing_overridden(curr_bs)) { 5677 /* 5678 * If the backing file was overridden, we can only compare 5679 * directly against the backing node's filename. 5680 */ 5681 5682 if (!filenames_refreshed) { 5683 /* 5684 * This will automatically refresh all of the 5685 * filenames in the rest of the backing chain, so we 5686 * only need to do this once. 5687 */ 5688 bdrv_refresh_filename(bs_below); 5689 filenames_refreshed = true; 5690 } 5691 5692 if (strcmp(backing_file, bs_below->filename) == 0) { 5693 retval = bs_below; 5694 break; 5695 } 5696 } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) { 5697 /* 5698 * If either of the filename paths is actually a protocol, then 5699 * compare unmodified paths; otherwise make paths relative. 5700 */ 5701 char *backing_file_full_ret; 5702 5703 if (strcmp(backing_file, curr_bs->backing_file) == 0) { 5704 retval = bs_below; 5705 break; 5706 } 5707 /* Also check against the full backing filename for the image */ 5708 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs, 5709 NULL); 5710 if (backing_file_full_ret) { 5711 bool equal = strcmp(backing_file, backing_file_full_ret) == 0; 5712 g_free(backing_file_full_ret); 5713 if (equal) { 5714 retval = bs_below; 5715 break; 5716 } 5717 } 5718 } else { 5719 /* If not an absolute filename path, make it relative to the current 5720 * image's filename path */ 5721 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file, 5722 NULL); 5723 /* We are going to compare canonicalized absolute pathnames */ 5724 if (!filename_tmp || !realpath(filename_tmp, filename_full)) { 5725 g_free(filename_tmp); 5726 continue; 5727 } 5728 g_free(filename_tmp); 5729 5730 /* We need to make sure the backing filename we are comparing against 5731 * is relative to the current image filename (or absolute) */ 5732 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL); 5733 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) { 5734 g_free(filename_tmp); 5735 continue; 5736 } 5737 g_free(filename_tmp); 5738 5739 if (strcmp(backing_file_full, filename_full) == 0) { 5740 retval = bs_below; 5741 break; 5742 } 5743 } 5744 } 5745 5746 g_free(filename_full); 5747 g_free(backing_file_full); 5748 return retval; 5749 } 5750 5751 void bdrv_init(void) 5752 { 5753 module_call_init(MODULE_INIT_BLOCK); 5754 } 5755 5756 void bdrv_init_with_whitelist(void) 5757 { 5758 use_bdrv_whitelist = 1; 5759 bdrv_init(); 5760 } 5761 5762 int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp) 5763 { 5764 BdrvChild *child, *parent; 5765 Error *local_err = NULL; 5766 int ret; 5767 BdrvDirtyBitmap *bm; 5768 5769 if (!bs->drv) { 5770 return -ENOMEDIUM; 5771 } 5772 5773 QLIST_FOREACH(child, &bs->children, next) { 5774 bdrv_co_invalidate_cache(child->bs, &local_err); 5775 if (local_err) { 5776 error_propagate(errp, local_err); 5777 return -EINVAL; 5778 } 5779 } 5780 5781 /* 5782 * Update permissions, they may differ for inactive nodes. 5783 * 5784 * Note that the required permissions of inactive images are always a 5785 * subset of the permissions required after activating the image. This 5786 * allows us to just get the permissions upfront without restricting 5787 * drv->bdrv_invalidate_cache(). 5788 * 5789 * It also means that in error cases, we don't have to try and revert to 5790 * the old permissions (which is an operation that could fail, too). We can 5791 * just keep the extended permissions for the next time that an activation 5792 * of the image is tried. 5793 */ 5794 if (bs->open_flags & BDRV_O_INACTIVE) { 5795 bs->open_flags &= ~BDRV_O_INACTIVE; 5796 ret = bdrv_refresh_perms(bs, errp); 5797 if (ret < 0) { 5798 bs->open_flags |= BDRV_O_INACTIVE; 5799 return ret; 5800 } 5801 5802 if (bs->drv->bdrv_co_invalidate_cache) { 5803 bs->drv->bdrv_co_invalidate_cache(bs, &local_err); 5804 if (local_err) { 5805 bs->open_flags |= BDRV_O_INACTIVE; 5806 error_propagate(errp, local_err); 5807 return -EINVAL; 5808 } 5809 } 5810 5811 FOR_EACH_DIRTY_BITMAP(bs, bm) { 5812 bdrv_dirty_bitmap_skip_store(bm, false); 5813 } 5814 5815 ret = refresh_total_sectors(bs, bs->total_sectors); 5816 if (ret < 0) { 5817 bs->open_flags |= BDRV_O_INACTIVE; 5818 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 5819 return ret; 5820 } 5821 } 5822 5823 QLIST_FOREACH(parent, &bs->parents, next_parent) { 5824 if (parent->klass->activate) { 5825 parent->klass->activate(parent, &local_err); 5826 if (local_err) { 5827 bs->open_flags |= BDRV_O_INACTIVE; 5828 error_propagate(errp, local_err); 5829 return -EINVAL; 5830 } 5831 } 5832 } 5833 5834 return 0; 5835 } 5836 5837 void bdrv_invalidate_cache_all(Error **errp) 5838 { 5839 BlockDriverState *bs; 5840 BdrvNextIterator it; 5841 5842 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 5843 AioContext *aio_context = bdrv_get_aio_context(bs); 5844 int ret; 5845 5846 aio_context_acquire(aio_context); 5847 ret = bdrv_invalidate_cache(bs, errp); 5848 aio_context_release(aio_context); 5849 if (ret < 0) { 5850 bdrv_next_cleanup(&it); 5851 return; 5852 } 5853 } 5854 } 5855 5856 static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active) 5857 { 5858 BdrvChild *parent; 5859 5860 QLIST_FOREACH(parent, &bs->parents, next_parent) { 5861 if (parent->klass->parent_is_bds) { 5862 BlockDriverState *parent_bs = parent->opaque; 5863 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) { 5864 return true; 5865 } 5866 } 5867 } 5868 5869 return false; 5870 } 5871 5872 static int bdrv_inactivate_recurse(BlockDriverState *bs) 5873 { 5874 BdrvChild *child, *parent; 5875 int ret; 5876 5877 if (!bs->drv) { 5878 return -ENOMEDIUM; 5879 } 5880 5881 /* Make sure that we don't inactivate a child before its parent. 5882 * It will be covered by recursion from the yet active parent. */ 5883 if (bdrv_has_bds_parent(bs, true)) { 5884 return 0; 5885 } 5886 5887 assert(!(bs->open_flags & BDRV_O_INACTIVE)); 5888 5889 /* Inactivate this node */ 5890 if (bs->drv->bdrv_inactivate) { 5891 ret = bs->drv->bdrv_inactivate(bs); 5892 if (ret < 0) { 5893 return ret; 5894 } 5895 } 5896 5897 QLIST_FOREACH(parent, &bs->parents, next_parent) { 5898 if (parent->klass->inactivate) { 5899 ret = parent->klass->inactivate(parent); 5900 if (ret < 0) { 5901 return ret; 5902 } 5903 } 5904 } 5905 5906 bs->open_flags |= BDRV_O_INACTIVE; 5907 5908 /* 5909 * Update permissions, they may differ for inactive nodes. 5910 * We only tried to loosen restrictions, so errors are not fatal, ignore 5911 * them. 5912 */ 5913 bdrv_refresh_perms(bs, NULL); 5914 5915 /* Recursively inactivate children */ 5916 QLIST_FOREACH(child, &bs->children, next) { 5917 ret = bdrv_inactivate_recurse(child->bs); 5918 if (ret < 0) { 5919 return ret; 5920 } 5921 } 5922 5923 return 0; 5924 } 5925 5926 int bdrv_inactivate_all(void) 5927 { 5928 BlockDriverState *bs = NULL; 5929 BdrvNextIterator it; 5930 int ret = 0; 5931 GSList *aio_ctxs = NULL, *ctx; 5932 5933 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 5934 AioContext *aio_context = bdrv_get_aio_context(bs); 5935 5936 if (!g_slist_find(aio_ctxs, aio_context)) { 5937 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context); 5938 aio_context_acquire(aio_context); 5939 } 5940 } 5941 5942 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 5943 /* Nodes with BDS parents are covered by recursion from the last 5944 * parent that gets inactivated. Don't inactivate them a second 5945 * time if that has already happened. */ 5946 if (bdrv_has_bds_parent(bs, false)) { 5947 continue; 5948 } 5949 ret = bdrv_inactivate_recurse(bs); 5950 if (ret < 0) { 5951 bdrv_next_cleanup(&it); 5952 goto out; 5953 } 5954 } 5955 5956 out: 5957 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) { 5958 AioContext *aio_context = ctx->data; 5959 aio_context_release(aio_context); 5960 } 5961 g_slist_free(aio_ctxs); 5962 5963 return ret; 5964 } 5965 5966 /**************************************************************/ 5967 /* removable device support */ 5968 5969 /** 5970 * Return TRUE if the media is present 5971 */ 5972 bool bdrv_is_inserted(BlockDriverState *bs) 5973 { 5974 BlockDriver *drv = bs->drv; 5975 BdrvChild *child; 5976 5977 if (!drv) { 5978 return false; 5979 } 5980 if (drv->bdrv_is_inserted) { 5981 return drv->bdrv_is_inserted(bs); 5982 } 5983 QLIST_FOREACH(child, &bs->children, next) { 5984 if (!bdrv_is_inserted(child->bs)) { 5985 return false; 5986 } 5987 } 5988 return true; 5989 } 5990 5991 /** 5992 * If eject_flag is TRUE, eject the media. Otherwise, close the tray 5993 */ 5994 void bdrv_eject(BlockDriverState *bs, bool eject_flag) 5995 { 5996 BlockDriver *drv = bs->drv; 5997 5998 if (drv && drv->bdrv_eject) { 5999 drv->bdrv_eject(bs, eject_flag); 6000 } 6001 } 6002 6003 /** 6004 * Lock or unlock the media (if it is locked, the user won't be able 6005 * to eject it manually). 6006 */ 6007 void bdrv_lock_medium(BlockDriverState *bs, bool locked) 6008 { 6009 BlockDriver *drv = bs->drv; 6010 6011 trace_bdrv_lock_medium(bs, locked); 6012 6013 if (drv && drv->bdrv_lock_medium) { 6014 drv->bdrv_lock_medium(bs, locked); 6015 } 6016 } 6017 6018 /* Get a reference to bs */ 6019 void bdrv_ref(BlockDriverState *bs) 6020 { 6021 bs->refcnt++; 6022 } 6023 6024 /* Release a previously grabbed reference to bs. 6025 * If after releasing, reference count is zero, the BlockDriverState is 6026 * deleted. */ 6027 void bdrv_unref(BlockDriverState *bs) 6028 { 6029 if (!bs) { 6030 return; 6031 } 6032 assert(bs->refcnt > 0); 6033 if (--bs->refcnt == 0) { 6034 bdrv_delete(bs); 6035 } 6036 } 6037 6038 struct BdrvOpBlocker { 6039 Error *reason; 6040 QLIST_ENTRY(BdrvOpBlocker) list; 6041 }; 6042 6043 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp) 6044 { 6045 BdrvOpBlocker *blocker; 6046 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 6047 if (!QLIST_EMPTY(&bs->op_blockers[op])) { 6048 blocker = QLIST_FIRST(&bs->op_blockers[op]); 6049 error_propagate_prepend(errp, error_copy(blocker->reason), 6050 "Node '%s' is busy: ", 6051 bdrv_get_device_or_node_name(bs)); 6052 return true; 6053 } 6054 return false; 6055 } 6056 6057 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason) 6058 { 6059 BdrvOpBlocker *blocker; 6060 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 6061 6062 blocker = g_new0(BdrvOpBlocker, 1); 6063 blocker->reason = reason; 6064 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); 6065 } 6066 6067 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason) 6068 { 6069 BdrvOpBlocker *blocker, *next; 6070 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 6071 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) { 6072 if (blocker->reason == reason) { 6073 QLIST_REMOVE(blocker, list); 6074 g_free(blocker); 6075 } 6076 } 6077 } 6078 6079 void bdrv_op_block_all(BlockDriverState *bs, Error *reason) 6080 { 6081 int i; 6082 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 6083 bdrv_op_block(bs, i, reason); 6084 } 6085 } 6086 6087 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason) 6088 { 6089 int i; 6090 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 6091 bdrv_op_unblock(bs, i, reason); 6092 } 6093 } 6094 6095 bool bdrv_op_blocker_is_empty(BlockDriverState *bs) 6096 { 6097 int i; 6098 6099 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 6100 if (!QLIST_EMPTY(&bs->op_blockers[i])) { 6101 return false; 6102 } 6103 } 6104 return true; 6105 } 6106 6107 void bdrv_img_create(const char *filename, const char *fmt, 6108 const char *base_filename, const char *base_fmt, 6109 char *options, uint64_t img_size, int flags, bool quiet, 6110 Error **errp) 6111 { 6112 QemuOptsList *create_opts = NULL; 6113 QemuOpts *opts = NULL; 6114 const char *backing_fmt, *backing_file; 6115 int64_t size; 6116 BlockDriver *drv, *proto_drv; 6117 Error *local_err = NULL; 6118 int ret = 0; 6119 6120 /* Find driver and parse its options */ 6121 drv = bdrv_find_format(fmt); 6122 if (!drv) { 6123 error_setg(errp, "Unknown file format '%s'", fmt); 6124 return; 6125 } 6126 6127 proto_drv = bdrv_find_protocol(filename, true, errp); 6128 if (!proto_drv) { 6129 return; 6130 } 6131 6132 if (!drv->create_opts) { 6133 error_setg(errp, "Format driver '%s' does not support image creation", 6134 drv->format_name); 6135 return; 6136 } 6137 6138 if (!proto_drv->create_opts) { 6139 error_setg(errp, "Protocol driver '%s' does not support image creation", 6140 proto_drv->format_name); 6141 return; 6142 } 6143 6144 /* Create parameter list */ 6145 create_opts = qemu_opts_append(create_opts, drv->create_opts); 6146 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts); 6147 6148 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort); 6149 6150 /* Parse -o options */ 6151 if (options) { 6152 if (!qemu_opts_do_parse(opts, options, NULL, errp)) { 6153 goto out; 6154 } 6155 } 6156 6157 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) { 6158 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort); 6159 } else if (img_size != UINT64_C(-1)) { 6160 error_setg(errp, "The image size must be specified only once"); 6161 goto out; 6162 } 6163 6164 if (base_filename) { 6165 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename, 6166 NULL)) { 6167 error_setg(errp, "Backing file not supported for file format '%s'", 6168 fmt); 6169 goto out; 6170 } 6171 } 6172 6173 if (base_fmt) { 6174 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) { 6175 error_setg(errp, "Backing file format not supported for file " 6176 "format '%s'", fmt); 6177 goto out; 6178 } 6179 } 6180 6181 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE); 6182 if (backing_file) { 6183 if (!strcmp(filename, backing_file)) { 6184 error_setg(errp, "Error: Trying to create an image with the " 6185 "same filename as the backing file"); 6186 goto out; 6187 } 6188 if (backing_file[0] == '\0') { 6189 error_setg(errp, "Expected backing file name, got empty string"); 6190 goto out; 6191 } 6192 } 6193 6194 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT); 6195 6196 /* The size for the image must always be specified, unless we have a backing 6197 * file and we have not been forbidden from opening it. */ 6198 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size); 6199 if (backing_file && !(flags & BDRV_O_NO_BACKING)) { 6200 BlockDriverState *bs; 6201 char *full_backing; 6202 int back_flags; 6203 QDict *backing_options = NULL; 6204 6205 full_backing = 6206 bdrv_get_full_backing_filename_from_filename(filename, backing_file, 6207 &local_err); 6208 if (local_err) { 6209 goto out; 6210 } 6211 assert(full_backing); 6212 6213 /* backing files always opened read-only */ 6214 back_flags = flags; 6215 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING); 6216 6217 backing_options = qdict_new(); 6218 if (backing_fmt) { 6219 qdict_put_str(backing_options, "driver", backing_fmt); 6220 } 6221 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true); 6222 6223 bs = bdrv_open(full_backing, NULL, backing_options, back_flags, 6224 &local_err); 6225 g_free(full_backing); 6226 if (!bs) { 6227 error_append_hint(&local_err, "Could not open backing image.\n"); 6228 goto out; 6229 } else { 6230 if (!backing_fmt) { 6231 warn_report("Deprecated use of backing file without explicit " 6232 "backing format (detected format of %s)", 6233 bs->drv->format_name); 6234 if (bs->drv != &bdrv_raw) { 6235 /* 6236 * A probe of raw deserves the most attention: 6237 * leaving the backing format out of the image 6238 * will ensure bs->probed is set (ensuring we 6239 * don't accidentally commit into the backing 6240 * file), and allow more spots to warn the users 6241 * to fix their toolchain when opening this image 6242 * later. For other images, we can safely record 6243 * the format that we probed. 6244 */ 6245 backing_fmt = bs->drv->format_name; 6246 qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, backing_fmt, 6247 NULL); 6248 } 6249 } 6250 if (size == -1) { 6251 /* Opened BS, have no size */ 6252 size = bdrv_getlength(bs); 6253 if (size < 0) { 6254 error_setg_errno(errp, -size, "Could not get size of '%s'", 6255 backing_file); 6256 bdrv_unref(bs); 6257 goto out; 6258 } 6259 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort); 6260 } 6261 bdrv_unref(bs); 6262 } 6263 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */ 6264 } else if (backing_file && !backing_fmt) { 6265 warn_report("Deprecated use of unopened backing file without " 6266 "explicit backing format, use of this image requires " 6267 "potentially unsafe format probing"); 6268 } 6269 6270 if (size == -1) { 6271 error_setg(errp, "Image creation needs a size parameter"); 6272 goto out; 6273 } 6274 6275 if (!quiet) { 6276 printf("Formatting '%s', fmt=%s ", filename, fmt); 6277 qemu_opts_print(opts, " "); 6278 puts(""); 6279 fflush(stdout); 6280 } 6281 6282 ret = bdrv_create(drv, filename, opts, &local_err); 6283 6284 if (ret == -EFBIG) { 6285 /* This is generally a better message than whatever the driver would 6286 * deliver (especially because of the cluster_size_hint), since that 6287 * is most probably not much different from "image too large". */ 6288 const char *cluster_size_hint = ""; 6289 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) { 6290 cluster_size_hint = " (try using a larger cluster size)"; 6291 } 6292 error_setg(errp, "The image size is too large for file format '%s'" 6293 "%s", fmt, cluster_size_hint); 6294 error_free(local_err); 6295 local_err = NULL; 6296 } 6297 6298 out: 6299 qemu_opts_del(opts); 6300 qemu_opts_free(create_opts); 6301 error_propagate(errp, local_err); 6302 } 6303 6304 AioContext *bdrv_get_aio_context(BlockDriverState *bs) 6305 { 6306 return bs ? bs->aio_context : qemu_get_aio_context(); 6307 } 6308 6309 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs) 6310 { 6311 Coroutine *self = qemu_coroutine_self(); 6312 AioContext *old_ctx = qemu_coroutine_get_aio_context(self); 6313 AioContext *new_ctx; 6314 6315 /* 6316 * Increase bs->in_flight to ensure that this operation is completed before 6317 * moving the node to a different AioContext. Read new_ctx only afterwards. 6318 */ 6319 bdrv_inc_in_flight(bs); 6320 6321 new_ctx = bdrv_get_aio_context(bs); 6322 aio_co_reschedule_self(new_ctx); 6323 return old_ctx; 6324 } 6325 6326 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx) 6327 { 6328 aio_co_reschedule_self(old_ctx); 6329 bdrv_dec_in_flight(bs); 6330 } 6331 6332 void coroutine_fn bdrv_co_lock(BlockDriverState *bs) 6333 { 6334 AioContext *ctx = bdrv_get_aio_context(bs); 6335 6336 /* In the main thread, bs->aio_context won't change concurrently */ 6337 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 6338 6339 /* 6340 * We're in coroutine context, so we already hold the lock of the main 6341 * loop AioContext. Don't lock it twice to avoid deadlocks. 6342 */ 6343 assert(qemu_in_coroutine()); 6344 if (ctx != qemu_get_aio_context()) { 6345 aio_context_acquire(ctx); 6346 } 6347 } 6348 6349 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs) 6350 { 6351 AioContext *ctx = bdrv_get_aio_context(bs); 6352 6353 assert(qemu_in_coroutine()); 6354 if (ctx != qemu_get_aio_context()) { 6355 aio_context_release(ctx); 6356 } 6357 } 6358 6359 void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co) 6360 { 6361 aio_co_enter(bdrv_get_aio_context(bs), co); 6362 } 6363 6364 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban) 6365 { 6366 QLIST_REMOVE(ban, list); 6367 g_free(ban); 6368 } 6369 6370 static void bdrv_detach_aio_context(BlockDriverState *bs) 6371 { 6372 BdrvAioNotifier *baf, *baf_tmp; 6373 6374 assert(!bs->walking_aio_notifiers); 6375 bs->walking_aio_notifiers = true; 6376 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) { 6377 if (baf->deleted) { 6378 bdrv_do_remove_aio_context_notifier(baf); 6379 } else { 6380 baf->detach_aio_context(baf->opaque); 6381 } 6382 } 6383 /* Never mind iterating again to check for ->deleted. bdrv_close() will 6384 * remove remaining aio notifiers if we aren't called again. 6385 */ 6386 bs->walking_aio_notifiers = false; 6387 6388 if (bs->drv && bs->drv->bdrv_detach_aio_context) { 6389 bs->drv->bdrv_detach_aio_context(bs); 6390 } 6391 6392 if (bs->quiesce_counter) { 6393 aio_enable_external(bs->aio_context); 6394 } 6395 bs->aio_context = NULL; 6396 } 6397 6398 static void bdrv_attach_aio_context(BlockDriverState *bs, 6399 AioContext *new_context) 6400 { 6401 BdrvAioNotifier *ban, *ban_tmp; 6402 6403 if (bs->quiesce_counter) { 6404 aio_disable_external(new_context); 6405 } 6406 6407 bs->aio_context = new_context; 6408 6409 if (bs->drv && bs->drv->bdrv_attach_aio_context) { 6410 bs->drv->bdrv_attach_aio_context(bs, new_context); 6411 } 6412 6413 assert(!bs->walking_aio_notifiers); 6414 bs->walking_aio_notifiers = true; 6415 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) { 6416 if (ban->deleted) { 6417 bdrv_do_remove_aio_context_notifier(ban); 6418 } else { 6419 ban->attached_aio_context(new_context, ban->opaque); 6420 } 6421 } 6422 bs->walking_aio_notifiers = false; 6423 } 6424 6425 /* 6426 * Changes the AioContext used for fd handlers, timers, and BHs by this 6427 * BlockDriverState and all its children and parents. 6428 * 6429 * Must be called from the main AioContext. 6430 * 6431 * The caller must own the AioContext lock for the old AioContext of bs, but it 6432 * must not own the AioContext lock for new_context (unless new_context is the 6433 * same as the current context of bs). 6434 * 6435 * @ignore will accumulate all visited BdrvChild object. The caller is 6436 * responsible for freeing the list afterwards. 6437 */ 6438 void bdrv_set_aio_context_ignore(BlockDriverState *bs, 6439 AioContext *new_context, GSList **ignore) 6440 { 6441 AioContext *old_context = bdrv_get_aio_context(bs); 6442 BdrvChild *child; 6443 6444 g_assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 6445 6446 if (old_context == new_context) { 6447 return; 6448 } 6449 6450 bdrv_drained_begin(bs); 6451 6452 QLIST_FOREACH(child, &bs->children, next) { 6453 if (g_slist_find(*ignore, child)) { 6454 continue; 6455 } 6456 *ignore = g_slist_prepend(*ignore, child); 6457 bdrv_set_aio_context_ignore(child->bs, new_context, ignore); 6458 } 6459 QLIST_FOREACH(child, &bs->parents, next_parent) { 6460 if (g_slist_find(*ignore, child)) { 6461 continue; 6462 } 6463 assert(child->klass->set_aio_ctx); 6464 *ignore = g_slist_prepend(*ignore, child); 6465 child->klass->set_aio_ctx(child, new_context, ignore); 6466 } 6467 6468 bdrv_detach_aio_context(bs); 6469 6470 /* Acquire the new context, if necessary */ 6471 if (qemu_get_aio_context() != new_context) { 6472 aio_context_acquire(new_context); 6473 } 6474 6475 bdrv_attach_aio_context(bs, new_context); 6476 6477 /* 6478 * If this function was recursively called from 6479 * bdrv_set_aio_context_ignore(), there may be nodes in the 6480 * subtree that have not yet been moved to the new AioContext. 6481 * Release the old one so bdrv_drained_end() can poll them. 6482 */ 6483 if (qemu_get_aio_context() != old_context) { 6484 aio_context_release(old_context); 6485 } 6486 6487 bdrv_drained_end(bs); 6488 6489 if (qemu_get_aio_context() != old_context) { 6490 aio_context_acquire(old_context); 6491 } 6492 if (qemu_get_aio_context() != new_context) { 6493 aio_context_release(new_context); 6494 } 6495 } 6496 6497 static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx, 6498 GSList **ignore, Error **errp) 6499 { 6500 if (g_slist_find(*ignore, c)) { 6501 return true; 6502 } 6503 *ignore = g_slist_prepend(*ignore, c); 6504 6505 /* 6506 * A BdrvChildClass that doesn't handle AioContext changes cannot 6507 * tolerate any AioContext changes 6508 */ 6509 if (!c->klass->can_set_aio_ctx) { 6510 char *user = bdrv_child_user_desc(c); 6511 error_setg(errp, "Changing iothreads is not supported by %s", user); 6512 g_free(user); 6513 return false; 6514 } 6515 if (!c->klass->can_set_aio_ctx(c, ctx, ignore, errp)) { 6516 assert(!errp || *errp); 6517 return false; 6518 } 6519 return true; 6520 } 6521 6522 bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx, 6523 GSList **ignore, Error **errp) 6524 { 6525 if (g_slist_find(*ignore, c)) { 6526 return true; 6527 } 6528 *ignore = g_slist_prepend(*ignore, c); 6529 return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp); 6530 } 6531 6532 /* @ignore will accumulate all visited BdrvChild object. The caller is 6533 * responsible for freeing the list afterwards. */ 6534 bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx, 6535 GSList **ignore, Error **errp) 6536 { 6537 BdrvChild *c; 6538 6539 if (bdrv_get_aio_context(bs) == ctx) { 6540 return true; 6541 } 6542 6543 QLIST_FOREACH(c, &bs->parents, next_parent) { 6544 if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) { 6545 return false; 6546 } 6547 } 6548 QLIST_FOREACH(c, &bs->children, next) { 6549 if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) { 6550 return false; 6551 } 6552 } 6553 6554 return true; 6555 } 6556 6557 int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, 6558 BdrvChild *ignore_child, Error **errp) 6559 { 6560 GSList *ignore; 6561 bool ret; 6562 6563 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL; 6564 ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp); 6565 g_slist_free(ignore); 6566 6567 if (!ret) { 6568 return -EPERM; 6569 } 6570 6571 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL; 6572 bdrv_set_aio_context_ignore(bs, ctx, &ignore); 6573 g_slist_free(ignore); 6574 6575 return 0; 6576 } 6577 6578 int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, 6579 Error **errp) 6580 { 6581 return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp); 6582 } 6583 6584 void bdrv_add_aio_context_notifier(BlockDriverState *bs, 6585 void (*attached_aio_context)(AioContext *new_context, void *opaque), 6586 void (*detach_aio_context)(void *opaque), void *opaque) 6587 { 6588 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1); 6589 *ban = (BdrvAioNotifier){ 6590 .attached_aio_context = attached_aio_context, 6591 .detach_aio_context = detach_aio_context, 6592 .opaque = opaque 6593 }; 6594 6595 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list); 6596 } 6597 6598 void bdrv_remove_aio_context_notifier(BlockDriverState *bs, 6599 void (*attached_aio_context)(AioContext *, 6600 void *), 6601 void (*detach_aio_context)(void *), 6602 void *opaque) 6603 { 6604 BdrvAioNotifier *ban, *ban_next; 6605 6606 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 6607 if (ban->attached_aio_context == attached_aio_context && 6608 ban->detach_aio_context == detach_aio_context && 6609 ban->opaque == opaque && 6610 ban->deleted == false) 6611 { 6612 if (bs->walking_aio_notifiers) { 6613 ban->deleted = true; 6614 } else { 6615 bdrv_do_remove_aio_context_notifier(ban); 6616 } 6617 return; 6618 } 6619 } 6620 6621 abort(); 6622 } 6623 6624 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts, 6625 BlockDriverAmendStatusCB *status_cb, void *cb_opaque, 6626 bool force, 6627 Error **errp) 6628 { 6629 if (!bs->drv) { 6630 error_setg(errp, "Node is ejected"); 6631 return -ENOMEDIUM; 6632 } 6633 if (!bs->drv->bdrv_amend_options) { 6634 error_setg(errp, "Block driver '%s' does not support option amendment", 6635 bs->drv->format_name); 6636 return -ENOTSUP; 6637 } 6638 return bs->drv->bdrv_amend_options(bs, opts, status_cb, 6639 cb_opaque, force, errp); 6640 } 6641 6642 /* 6643 * This function checks whether the given @to_replace is allowed to be 6644 * replaced by a node that always shows the same data as @bs. This is 6645 * used for example to verify whether the mirror job can replace 6646 * @to_replace by the target mirrored from @bs. 6647 * To be replaceable, @bs and @to_replace may either be guaranteed to 6648 * always show the same data (because they are only connected through 6649 * filters), or some driver may allow replacing one of its children 6650 * because it can guarantee that this child's data is not visible at 6651 * all (for example, for dissenting quorum children that have no other 6652 * parents). 6653 */ 6654 bool bdrv_recurse_can_replace(BlockDriverState *bs, 6655 BlockDriverState *to_replace) 6656 { 6657 BlockDriverState *filtered; 6658 6659 if (!bs || !bs->drv) { 6660 return false; 6661 } 6662 6663 if (bs == to_replace) { 6664 return true; 6665 } 6666 6667 /* See what the driver can do */ 6668 if (bs->drv->bdrv_recurse_can_replace) { 6669 return bs->drv->bdrv_recurse_can_replace(bs, to_replace); 6670 } 6671 6672 /* For filters without an own implementation, we can recurse on our own */ 6673 filtered = bdrv_filter_bs(bs); 6674 if (filtered) { 6675 return bdrv_recurse_can_replace(filtered, to_replace); 6676 } 6677 6678 /* Safe default */ 6679 return false; 6680 } 6681 6682 /* 6683 * Check whether the given @node_name can be replaced by a node that 6684 * has the same data as @parent_bs. If so, return @node_name's BDS; 6685 * NULL otherwise. 6686 * 6687 * @node_name must be a (recursive) *child of @parent_bs (or this 6688 * function will return NULL). 6689 * 6690 * The result (whether the node can be replaced or not) is only valid 6691 * for as long as no graph or permission changes occur. 6692 */ 6693 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs, 6694 const char *node_name, Error **errp) 6695 { 6696 BlockDriverState *to_replace_bs = bdrv_find_node(node_name); 6697 AioContext *aio_context; 6698 6699 if (!to_replace_bs) { 6700 error_setg(errp, "Node name '%s' not found", node_name); 6701 return NULL; 6702 } 6703 6704 aio_context = bdrv_get_aio_context(to_replace_bs); 6705 aio_context_acquire(aio_context); 6706 6707 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) { 6708 to_replace_bs = NULL; 6709 goto out; 6710 } 6711 6712 /* We don't want arbitrary node of the BDS chain to be replaced only the top 6713 * most non filter in order to prevent data corruption. 6714 * Another benefit is that this tests exclude backing files which are 6715 * blocked by the backing blockers. 6716 */ 6717 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) { 6718 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', " 6719 "because it cannot be guaranteed that doing so would not " 6720 "lead to an abrupt change of visible data", 6721 node_name, parent_bs->node_name); 6722 to_replace_bs = NULL; 6723 goto out; 6724 } 6725 6726 out: 6727 aio_context_release(aio_context); 6728 return to_replace_bs; 6729 } 6730 6731 /** 6732 * Iterates through the list of runtime option keys that are said to 6733 * be "strong" for a BDS. An option is called "strong" if it changes 6734 * a BDS's data. For example, the null block driver's "size" and 6735 * "read-zeroes" options are strong, but its "latency-ns" option is 6736 * not. 6737 * 6738 * If a key returned by this function ends with a dot, all options 6739 * starting with that prefix are strong. 6740 */ 6741 static const char *const *strong_options(BlockDriverState *bs, 6742 const char *const *curopt) 6743 { 6744 static const char *const global_options[] = { 6745 "driver", "filename", NULL 6746 }; 6747 6748 if (!curopt) { 6749 return &global_options[0]; 6750 } 6751 6752 curopt++; 6753 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) { 6754 curopt = bs->drv->strong_runtime_opts; 6755 } 6756 6757 return (curopt && *curopt) ? curopt : NULL; 6758 } 6759 6760 /** 6761 * Copies all strong runtime options from bs->options to the given 6762 * QDict. The set of strong option keys is determined by invoking 6763 * strong_options(). 6764 * 6765 * Returns true iff any strong option was present in bs->options (and 6766 * thus copied to the target QDict) with the exception of "filename" 6767 * and "driver". The caller is expected to use this value to decide 6768 * whether the existence of strong options prevents the generation of 6769 * a plain filename. 6770 */ 6771 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs) 6772 { 6773 bool found_any = false; 6774 const char *const *option_name = NULL; 6775 6776 if (!bs->drv) { 6777 return false; 6778 } 6779 6780 while ((option_name = strong_options(bs, option_name))) { 6781 bool option_given = false; 6782 6783 assert(strlen(*option_name) > 0); 6784 if ((*option_name)[strlen(*option_name) - 1] != '.') { 6785 QObject *entry = qdict_get(bs->options, *option_name); 6786 if (!entry) { 6787 continue; 6788 } 6789 6790 qdict_put_obj(d, *option_name, qobject_ref(entry)); 6791 option_given = true; 6792 } else { 6793 const QDictEntry *entry; 6794 for (entry = qdict_first(bs->options); entry; 6795 entry = qdict_next(bs->options, entry)) 6796 { 6797 if (strstart(qdict_entry_key(entry), *option_name, NULL)) { 6798 qdict_put_obj(d, qdict_entry_key(entry), 6799 qobject_ref(qdict_entry_value(entry))); 6800 option_given = true; 6801 } 6802 } 6803 } 6804 6805 /* While "driver" and "filename" need to be included in a JSON filename, 6806 * their existence does not prohibit generation of a plain filename. */ 6807 if (!found_any && option_given && 6808 strcmp(*option_name, "driver") && strcmp(*option_name, "filename")) 6809 { 6810 found_any = true; 6811 } 6812 } 6813 6814 if (!qdict_haskey(d, "driver")) { 6815 /* Drivers created with bdrv_new_open_driver() may not have a 6816 * @driver option. Add it here. */ 6817 qdict_put_str(d, "driver", bs->drv->format_name); 6818 } 6819 6820 return found_any; 6821 } 6822 6823 /* Note: This function may return false positives; it may return true 6824 * even if opening the backing file specified by bs's image header 6825 * would result in exactly bs->backing. */ 6826 bool bdrv_backing_overridden(BlockDriverState *bs) 6827 { 6828 if (bs->backing) { 6829 return strcmp(bs->auto_backing_file, 6830 bs->backing->bs->filename); 6831 } else { 6832 /* No backing BDS, so if the image header reports any backing 6833 * file, it must have been suppressed */ 6834 return bs->auto_backing_file[0] != '\0'; 6835 } 6836 } 6837 6838 /* Updates the following BDS fields: 6839 * - exact_filename: A filename which may be used for opening a block device 6840 * which (mostly) equals the given BDS (even without any 6841 * other options; so reading and writing must return the same 6842 * results, but caching etc. may be different) 6843 * - full_open_options: Options which, when given when opening a block device 6844 * (without a filename), result in a BDS (mostly) 6845 * equalling the given one 6846 * - filename: If exact_filename is set, it is copied here. Otherwise, 6847 * full_open_options is converted to a JSON object, prefixed with 6848 * "json:" (for use through the JSON pseudo protocol) and put here. 6849 */ 6850 void bdrv_refresh_filename(BlockDriverState *bs) 6851 { 6852 BlockDriver *drv = bs->drv; 6853 BdrvChild *child; 6854 BlockDriverState *primary_child_bs; 6855 QDict *opts; 6856 bool backing_overridden; 6857 bool generate_json_filename; /* Whether our default implementation should 6858 fill exact_filename (false) or not (true) */ 6859 6860 if (!drv) { 6861 return; 6862 } 6863 6864 /* This BDS's file name may depend on any of its children's file names, so 6865 * refresh those first */ 6866 QLIST_FOREACH(child, &bs->children, next) { 6867 bdrv_refresh_filename(child->bs); 6868 } 6869 6870 if (bs->implicit) { 6871 /* For implicit nodes, just copy everything from the single child */ 6872 child = QLIST_FIRST(&bs->children); 6873 assert(QLIST_NEXT(child, next) == NULL); 6874 6875 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 6876 child->bs->exact_filename); 6877 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename); 6878 6879 qobject_unref(bs->full_open_options); 6880 bs->full_open_options = qobject_ref(child->bs->full_open_options); 6881 6882 return; 6883 } 6884 6885 backing_overridden = bdrv_backing_overridden(bs); 6886 6887 if (bs->open_flags & BDRV_O_NO_IO) { 6888 /* Without I/O, the backing file does not change anything. 6889 * Therefore, in such a case (primarily qemu-img), we can 6890 * pretend the backing file has not been overridden even if 6891 * it technically has been. */ 6892 backing_overridden = false; 6893 } 6894 6895 /* Gather the options QDict */ 6896 opts = qdict_new(); 6897 generate_json_filename = append_strong_runtime_options(opts, bs); 6898 generate_json_filename |= backing_overridden; 6899 6900 if (drv->bdrv_gather_child_options) { 6901 /* Some block drivers may not want to present all of their children's 6902 * options, or name them differently from BdrvChild.name */ 6903 drv->bdrv_gather_child_options(bs, opts, backing_overridden); 6904 } else { 6905 QLIST_FOREACH(child, &bs->children, next) { 6906 if (child == bs->backing && !backing_overridden) { 6907 /* We can skip the backing BDS if it has not been overridden */ 6908 continue; 6909 } 6910 6911 qdict_put(opts, child->name, 6912 qobject_ref(child->bs->full_open_options)); 6913 } 6914 6915 if (backing_overridden && !bs->backing) { 6916 /* Force no backing file */ 6917 qdict_put_null(opts, "backing"); 6918 } 6919 } 6920 6921 qobject_unref(bs->full_open_options); 6922 bs->full_open_options = opts; 6923 6924 primary_child_bs = bdrv_primary_bs(bs); 6925 6926 if (drv->bdrv_refresh_filename) { 6927 /* Obsolete information is of no use here, so drop the old file name 6928 * information before refreshing it */ 6929 bs->exact_filename[0] = '\0'; 6930 6931 drv->bdrv_refresh_filename(bs); 6932 } else if (primary_child_bs) { 6933 /* 6934 * Try to reconstruct valid information from the underlying 6935 * file -- this only works for format nodes (filter nodes 6936 * cannot be probed and as such must be selected by the user 6937 * either through an options dict, or through a special 6938 * filename which the filter driver must construct in its 6939 * .bdrv_refresh_filename() implementation). 6940 */ 6941 6942 bs->exact_filename[0] = '\0'; 6943 6944 /* 6945 * We can use the underlying file's filename if: 6946 * - it has a filename, 6947 * - the current BDS is not a filter, 6948 * - the file is a protocol BDS, and 6949 * - opening that file (as this BDS's format) will automatically create 6950 * the BDS tree we have right now, that is: 6951 * - the user did not significantly change this BDS's behavior with 6952 * some explicit (strong) options 6953 * - no non-file child of this BDS has been overridden by the user 6954 * Both of these conditions are represented by generate_json_filename. 6955 */ 6956 if (primary_child_bs->exact_filename[0] && 6957 primary_child_bs->drv->bdrv_file_open && 6958 !drv->is_filter && !generate_json_filename) 6959 { 6960 strcpy(bs->exact_filename, primary_child_bs->exact_filename); 6961 } 6962 } 6963 6964 if (bs->exact_filename[0]) { 6965 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename); 6966 } else { 6967 GString *json = qobject_to_json(QOBJECT(bs->full_open_options)); 6968 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s", 6969 json->str) >= sizeof(bs->filename)) { 6970 /* Give user a hint if we truncated things. */ 6971 strcpy(bs->filename + sizeof(bs->filename) - 4, "..."); 6972 } 6973 g_string_free(json, true); 6974 } 6975 } 6976 6977 char *bdrv_dirname(BlockDriverState *bs, Error **errp) 6978 { 6979 BlockDriver *drv = bs->drv; 6980 BlockDriverState *child_bs; 6981 6982 if (!drv) { 6983 error_setg(errp, "Node '%s' is ejected", bs->node_name); 6984 return NULL; 6985 } 6986 6987 if (drv->bdrv_dirname) { 6988 return drv->bdrv_dirname(bs, errp); 6989 } 6990 6991 child_bs = bdrv_primary_bs(bs); 6992 if (child_bs) { 6993 return bdrv_dirname(child_bs, errp); 6994 } 6995 6996 bdrv_refresh_filename(bs); 6997 if (bs->exact_filename[0] != '\0') { 6998 return path_combine(bs->exact_filename, ""); 6999 } 7000 7001 error_setg(errp, "Cannot generate a base directory for %s nodes", 7002 drv->format_name); 7003 return NULL; 7004 } 7005 7006 /* 7007 * Hot add/remove a BDS's child. So the user can take a child offline when 7008 * it is broken and take a new child online 7009 */ 7010 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, 7011 Error **errp) 7012 { 7013 7014 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) { 7015 error_setg(errp, "The node %s does not support adding a child", 7016 bdrv_get_device_or_node_name(parent_bs)); 7017 return; 7018 } 7019 7020 if (!QLIST_EMPTY(&child_bs->parents)) { 7021 error_setg(errp, "The node %s already has a parent", 7022 child_bs->node_name); 7023 return; 7024 } 7025 7026 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp); 7027 } 7028 7029 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) 7030 { 7031 BdrvChild *tmp; 7032 7033 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) { 7034 error_setg(errp, "The node %s does not support removing a child", 7035 bdrv_get_device_or_node_name(parent_bs)); 7036 return; 7037 } 7038 7039 QLIST_FOREACH(tmp, &parent_bs->children, next) { 7040 if (tmp == child) { 7041 break; 7042 } 7043 } 7044 7045 if (!tmp) { 7046 error_setg(errp, "The node %s does not have a child named %s", 7047 bdrv_get_device_or_node_name(parent_bs), 7048 bdrv_get_device_or_node_name(child->bs)); 7049 return; 7050 } 7051 7052 parent_bs->drv->bdrv_del_child(parent_bs, child, errp); 7053 } 7054 7055 int bdrv_make_empty(BdrvChild *c, Error **errp) 7056 { 7057 BlockDriver *drv = c->bs->drv; 7058 int ret; 7059 7060 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)); 7061 7062 if (!drv->bdrv_make_empty) { 7063 error_setg(errp, "%s does not support emptying nodes", 7064 drv->format_name); 7065 return -ENOTSUP; 7066 } 7067 7068 ret = drv->bdrv_make_empty(c->bs); 7069 if (ret < 0) { 7070 error_setg_errno(errp, -ret, "Failed to empty %s", 7071 c->bs->filename); 7072 return ret; 7073 } 7074 7075 return 0; 7076 } 7077 7078 /* 7079 * Return the child that @bs acts as an overlay for, and from which data may be 7080 * copied in COW or COR operations. Usually this is the backing file. 7081 */ 7082 BdrvChild *bdrv_cow_child(BlockDriverState *bs) 7083 { 7084 if (!bs || !bs->drv) { 7085 return NULL; 7086 } 7087 7088 if (bs->drv->is_filter) { 7089 return NULL; 7090 } 7091 7092 if (!bs->backing) { 7093 return NULL; 7094 } 7095 7096 assert(bs->backing->role & BDRV_CHILD_COW); 7097 return bs->backing; 7098 } 7099 7100 /* 7101 * If @bs acts as a filter for exactly one of its children, return 7102 * that child. 7103 */ 7104 BdrvChild *bdrv_filter_child(BlockDriverState *bs) 7105 { 7106 BdrvChild *c; 7107 7108 if (!bs || !bs->drv) { 7109 return NULL; 7110 } 7111 7112 if (!bs->drv->is_filter) { 7113 return NULL; 7114 } 7115 7116 /* Only one of @backing or @file may be used */ 7117 assert(!(bs->backing && bs->file)); 7118 7119 c = bs->backing ?: bs->file; 7120 if (!c) { 7121 return NULL; 7122 } 7123 7124 assert(c->role & BDRV_CHILD_FILTERED); 7125 return c; 7126 } 7127 7128 /* 7129 * Return either the result of bdrv_cow_child() or bdrv_filter_child(), 7130 * whichever is non-NULL. 7131 * 7132 * Return NULL if both are NULL. 7133 */ 7134 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs) 7135 { 7136 BdrvChild *cow_child = bdrv_cow_child(bs); 7137 BdrvChild *filter_child = bdrv_filter_child(bs); 7138 7139 /* Filter nodes cannot have COW backing files */ 7140 assert(!(cow_child && filter_child)); 7141 7142 return cow_child ?: filter_child; 7143 } 7144 7145 /* 7146 * Return the primary child of this node: For filters, that is the 7147 * filtered child. For other nodes, that is usually the child storing 7148 * metadata. 7149 * (A generally more helpful description is that this is (usually) the 7150 * child that has the same filename as @bs.) 7151 * 7152 * Drivers do not necessarily have a primary child; for example quorum 7153 * does not. 7154 */ 7155 BdrvChild *bdrv_primary_child(BlockDriverState *bs) 7156 { 7157 BdrvChild *c, *found = NULL; 7158 7159 QLIST_FOREACH(c, &bs->children, next) { 7160 if (c->role & BDRV_CHILD_PRIMARY) { 7161 assert(!found); 7162 found = c; 7163 } 7164 } 7165 7166 return found; 7167 } 7168 7169 static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs, 7170 bool stop_on_explicit_filter) 7171 { 7172 BdrvChild *c; 7173 7174 if (!bs) { 7175 return NULL; 7176 } 7177 7178 while (!(stop_on_explicit_filter && !bs->implicit)) { 7179 c = bdrv_filter_child(bs); 7180 if (!c) { 7181 /* 7182 * A filter that is embedded in a working block graph must 7183 * have a child. Assert this here so this function does 7184 * not return a filter node that is not expected by the 7185 * caller. 7186 */ 7187 assert(!bs->drv || !bs->drv->is_filter); 7188 break; 7189 } 7190 bs = c->bs; 7191 } 7192 /* 7193 * Note that this treats nodes with bs->drv == NULL as not being 7194 * filters (bs->drv == NULL should be replaced by something else 7195 * anyway). 7196 * The advantage of this behavior is that this function will thus 7197 * always return a non-NULL value (given a non-NULL @bs). 7198 */ 7199 7200 return bs; 7201 } 7202 7203 /* 7204 * Return the first BDS that has not been added implicitly or that 7205 * does not have a filtered child down the chain starting from @bs 7206 * (including @bs itself). 7207 */ 7208 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs) 7209 { 7210 return bdrv_do_skip_filters(bs, true); 7211 } 7212 7213 /* 7214 * Return the first BDS that does not have a filtered child down the 7215 * chain starting from @bs (including @bs itself). 7216 */ 7217 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs) 7218 { 7219 return bdrv_do_skip_filters(bs, false); 7220 } 7221 7222 /* 7223 * For a backing chain, return the first non-filter backing image of 7224 * the first non-filter image. 7225 */ 7226 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs) 7227 { 7228 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs))); 7229 } 7230