hw/intc/sh_intc: Inline and drop sh_intc_source() function
[qemu/rayw.git] / block.c
blob45f653a88b94909809880aaf115ec90a0626a3ae
1 /*
2 * QEMU System Emulator block driver
4 * Copyright (c) 2003 Fabrice Bellard
5 * Copyright (c) 2020 Virtuozzo International GmbH.
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
26 #include "qemu/osdep.h"
27 #include "block/trace.h"
28 #include "block/block_int.h"
29 #include "block/blockjob.h"
30 #include "block/fuse.h"
31 #include "block/nbd.h"
32 #include "block/qdict.h"
33 #include "qemu/error-report.h"
34 #include "block/module_block.h"
35 #include "qemu/main-loop.h"
36 #include "qemu/module.h"
37 #include "qapi/error.h"
38 #include "qapi/qmp/qdict.h"
39 #include "qapi/qmp/qjson.h"
40 #include "qapi/qmp/qnull.h"
41 #include "qapi/qmp/qstring.h"
42 #include "qapi/qobject-output-visitor.h"
43 #include "qapi/qapi-visit-block-core.h"
44 #include "sysemu/block-backend.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 "qemu/range.h"
53 #include "qemu/rcu.h"
54 #include "block/coroutines.h"
56 #ifdef CONFIG_BSD
57 #include <sys/ioctl.h>
58 #include <sys/queue.h>
59 #if defined(HAVE_SYS_DISK_H)
60 #include <sys/disk.h>
61 #endif
62 #endif
64 #ifdef _WIN32
65 #include <windows.h>
66 #endif
68 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
70 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
71 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
73 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
74 QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
76 static QLIST_HEAD(, BlockDriver) bdrv_drivers =
77 QLIST_HEAD_INITIALIZER(bdrv_drivers);
79 static BlockDriverState *bdrv_open_inherit(const char *filename,
80 const char *reference,
81 QDict *options, int flags,
82 BlockDriverState *parent,
83 const BdrvChildClass *child_class,
84 BdrvChildRole child_role,
85 Error **errp);
87 static void bdrv_replace_child_noperm(BdrvChild *child,
88 BlockDriverState *new_bs);
89 static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
90 BdrvChild *child,
91 Transaction *tran);
92 static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs,
93 Transaction *tran);
95 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
96 BlockReopenQueue *queue,
97 Transaction *change_child_tran, Error **errp);
98 static void bdrv_reopen_commit(BDRVReopenState *reopen_state);
99 static void bdrv_reopen_abort(BDRVReopenState *reopen_state);
101 /* If non-zero, use only whitelisted block drivers */
102 static int use_bdrv_whitelist;
104 #ifdef _WIN32
105 static int is_windows_drive_prefix(const char *filename)
107 return (((filename[0] >= 'a' && filename[0] <= 'z') ||
108 (filename[0] >= 'A' && filename[0] <= 'Z')) &&
109 filename[1] == ':');
112 int is_windows_drive(const char *filename)
114 if (is_windows_drive_prefix(filename) &&
115 filename[2] == '\0')
116 return 1;
117 if (strstart(filename, "\\\\.\\", NULL) ||
118 strstart(filename, "//./", NULL))
119 return 1;
120 return 0;
122 #endif
124 size_t bdrv_opt_mem_align(BlockDriverState *bs)
126 if (!bs || !bs->drv) {
127 /* page size or 4k (hdd sector size) should be on the safe side */
128 return MAX(4096, qemu_real_host_page_size);
131 return bs->bl.opt_mem_alignment;
134 size_t bdrv_min_mem_align(BlockDriverState *bs)
136 if (!bs || !bs->drv) {
137 /* page size or 4k (hdd sector size) should be on the safe side */
138 return MAX(4096, qemu_real_host_page_size);
141 return bs->bl.min_mem_alignment;
144 /* check if the path starts with "<protocol>:" */
145 int path_has_protocol(const char *path)
147 const char *p;
149 #ifdef _WIN32
150 if (is_windows_drive(path) ||
151 is_windows_drive_prefix(path)) {
152 return 0;
154 p = path + strcspn(path, ":/\\");
155 #else
156 p = path + strcspn(path, ":/");
157 #endif
159 return *p == ':';
162 int path_is_absolute(const char *path)
164 #ifdef _WIN32
165 /* specific case for names like: "\\.\d:" */
166 if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
167 return 1;
169 return (*path == '/' || *path == '\\');
170 #else
171 return (*path == '/');
172 #endif
175 /* if filename is absolute, just return its duplicate. Otherwise, build a
176 path to it by considering it is relative to base_path. URL are
177 supported. */
178 char *path_combine(const char *base_path, const char *filename)
180 const char *protocol_stripped = NULL;
181 const char *p, *p1;
182 char *result;
183 int len;
185 if (path_is_absolute(filename)) {
186 return g_strdup(filename);
189 if (path_has_protocol(base_path)) {
190 protocol_stripped = strchr(base_path, ':');
191 if (protocol_stripped) {
192 protocol_stripped++;
195 p = protocol_stripped ?: base_path;
197 p1 = strrchr(base_path, '/');
198 #ifdef _WIN32
200 const char *p2;
201 p2 = strrchr(base_path, '\\');
202 if (!p1 || p2 > p1) {
203 p1 = p2;
206 #endif
207 if (p1) {
208 p1++;
209 } else {
210 p1 = base_path;
212 if (p1 > p) {
213 p = p1;
215 len = p - base_path;
217 result = g_malloc(len + strlen(filename) + 1);
218 memcpy(result, base_path, len);
219 strcpy(result + len, filename);
221 return result;
225 * Helper function for bdrv_parse_filename() implementations to remove optional
226 * protocol prefixes (especially "file:") from a filename and for putting the
227 * stripped filename into the options QDict if there is such a prefix.
229 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
230 QDict *options)
232 if (strstart(filename, prefix, &filename)) {
233 /* Stripping the explicit protocol prefix may result in a protocol
234 * prefix being (wrongly) detected (if the filename contains a colon) */
235 if (path_has_protocol(filename)) {
236 GString *fat_filename;
238 /* This means there is some colon before the first slash; therefore,
239 * this cannot be an absolute path */
240 assert(!path_is_absolute(filename));
242 /* And we can thus fix the protocol detection issue by prefixing it
243 * by "./" */
244 fat_filename = g_string_new("./");
245 g_string_append(fat_filename, filename);
247 assert(!path_has_protocol(fat_filename->str));
249 qdict_put(options, "filename",
250 qstring_from_gstring(fat_filename));
251 } else {
252 /* If no protocol prefix was detected, we can use the shortened
253 * filename as-is */
254 qdict_put_str(options, "filename", filename);
260 /* Returns whether the image file is opened as read-only. Note that this can
261 * return false and writing to the image file is still not possible because the
262 * image is inactivated. */
263 bool bdrv_is_read_only(BlockDriverState *bs)
265 return !(bs->open_flags & BDRV_O_RDWR);
268 int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
269 bool ignore_allow_rdw, Error **errp)
271 /* Do not set read_only if copy_on_read is enabled */
272 if (bs->copy_on_read && read_only) {
273 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
274 bdrv_get_device_or_node_name(bs));
275 return -EINVAL;
278 /* Do not clear read_only if it is prohibited */
279 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
280 !ignore_allow_rdw)
282 error_setg(errp, "Node '%s' is read only",
283 bdrv_get_device_or_node_name(bs));
284 return -EPERM;
287 return 0;
291 * Called by a driver that can only provide a read-only image.
293 * Returns 0 if the node is already read-only or it could switch the node to
294 * read-only because BDRV_O_AUTO_RDONLY is set.
296 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
297 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
298 * is not NULL, it is used as the error message for the Error object.
300 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
301 Error **errp)
303 int ret = 0;
305 if (!(bs->open_flags & BDRV_O_RDWR)) {
306 return 0;
308 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
309 goto fail;
312 ret = bdrv_can_set_read_only(bs, true, false, NULL);
313 if (ret < 0) {
314 goto fail;
317 bs->open_flags &= ~BDRV_O_RDWR;
319 return 0;
321 fail:
322 error_setg(errp, "%s", errmsg ?: "Image is read-only");
323 return -EACCES;
327 * If @backing is empty, this function returns NULL without setting
328 * @errp. In all other cases, NULL will only be returned with @errp
329 * set.
331 * Therefore, a return value of NULL without @errp set means that
332 * there is no backing file; if @errp is set, there is one but its
333 * absolute filename cannot be generated.
335 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
336 const char *backing,
337 Error **errp)
339 if (backing[0] == '\0') {
340 return NULL;
341 } else if (path_has_protocol(backing) || path_is_absolute(backing)) {
342 return g_strdup(backing);
343 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
344 error_setg(errp, "Cannot use relative backing file names for '%s'",
345 backed);
346 return NULL;
347 } else {
348 return path_combine(backed, backing);
353 * If @filename is empty or NULL, this function returns NULL without
354 * setting @errp. In all other cases, NULL will only be returned with
355 * @errp set.
357 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
358 const char *filename, Error **errp)
360 char *dir, *full_name;
362 if (!filename || filename[0] == '\0') {
363 return NULL;
364 } else if (path_has_protocol(filename) || path_is_absolute(filename)) {
365 return g_strdup(filename);
368 dir = bdrv_dirname(relative_to, errp);
369 if (!dir) {
370 return NULL;
373 full_name = g_strconcat(dir, filename, NULL);
374 g_free(dir);
375 return full_name;
378 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
380 return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
383 void bdrv_register(BlockDriver *bdrv)
385 assert(bdrv->format_name);
386 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
389 BlockDriverState *bdrv_new(void)
391 BlockDriverState *bs;
392 int i;
394 bs = g_new0(BlockDriverState, 1);
395 QLIST_INIT(&bs->dirty_bitmaps);
396 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
397 QLIST_INIT(&bs->op_blockers[i]);
399 qemu_co_mutex_init(&bs->reqs_lock);
400 qemu_mutex_init(&bs->dirty_bitmap_mutex);
401 bs->refcnt = 1;
402 bs->aio_context = qemu_get_aio_context();
404 qemu_co_queue_init(&bs->flush_queue);
406 qemu_co_mutex_init(&bs->bsc_modify_lock);
407 bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1);
409 for (i = 0; i < bdrv_drain_all_count; i++) {
410 bdrv_drained_begin(bs);
413 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
415 return bs;
418 static BlockDriver *bdrv_do_find_format(const char *format_name)
420 BlockDriver *drv1;
422 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
423 if (!strcmp(drv1->format_name, format_name)) {
424 return drv1;
428 return NULL;
431 BlockDriver *bdrv_find_format(const char *format_name)
433 BlockDriver *drv1;
434 int i;
436 drv1 = bdrv_do_find_format(format_name);
437 if (drv1) {
438 return drv1;
441 /* The driver isn't registered, maybe we need to load a module */
442 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
443 if (!strcmp(block_driver_modules[i].format_name, format_name)) {
444 block_module_load_one(block_driver_modules[i].library_name);
445 break;
449 return bdrv_do_find_format(format_name);
452 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
454 static const char *whitelist_rw[] = {
455 CONFIG_BDRV_RW_WHITELIST
456 NULL
458 static const char *whitelist_ro[] = {
459 CONFIG_BDRV_RO_WHITELIST
460 NULL
462 const char **p;
464 if (!whitelist_rw[0] && !whitelist_ro[0]) {
465 return 1; /* no whitelist, anything goes */
468 for (p = whitelist_rw; *p; p++) {
469 if (!strcmp(format_name, *p)) {
470 return 1;
473 if (read_only) {
474 for (p = whitelist_ro; *p; p++) {
475 if (!strcmp(format_name, *p)) {
476 return 1;
480 return 0;
483 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
485 return bdrv_format_is_whitelisted(drv->format_name, read_only);
488 bool bdrv_uses_whitelist(void)
490 return use_bdrv_whitelist;
493 typedef struct CreateCo {
494 BlockDriver *drv;
495 char *filename;
496 QemuOpts *opts;
497 int ret;
498 Error *err;
499 } CreateCo;
501 static void coroutine_fn bdrv_create_co_entry(void *opaque)
503 Error *local_err = NULL;
504 int ret;
506 CreateCo *cco = opaque;
507 assert(cco->drv);
509 ret = cco->drv->bdrv_co_create_opts(cco->drv,
510 cco->filename, cco->opts, &local_err);
511 error_propagate(&cco->err, local_err);
512 cco->ret = ret;
515 int bdrv_create(BlockDriver *drv, const char* filename,
516 QemuOpts *opts, Error **errp)
518 int ret;
520 Coroutine *co;
521 CreateCo cco = {
522 .drv = drv,
523 .filename = g_strdup(filename),
524 .opts = opts,
525 .ret = NOT_DONE,
526 .err = NULL,
529 if (!drv->bdrv_co_create_opts) {
530 error_setg(errp, "Driver '%s' does not support image creation", drv->format_name);
531 ret = -ENOTSUP;
532 goto out;
535 if (qemu_in_coroutine()) {
536 /* Fast-path if already in coroutine context */
537 bdrv_create_co_entry(&cco);
538 } else {
539 co = qemu_coroutine_create(bdrv_create_co_entry, &cco);
540 qemu_coroutine_enter(co);
541 while (cco.ret == NOT_DONE) {
542 aio_poll(qemu_get_aio_context(), true);
546 ret = cco.ret;
547 if (ret < 0) {
548 if (cco.err) {
549 error_propagate(errp, cco.err);
550 } else {
551 error_setg_errno(errp, -ret, "Could not create image");
555 out:
556 g_free(cco.filename);
557 return ret;
561 * Helper function for bdrv_create_file_fallback(): Resize @blk to at
562 * least the given @minimum_size.
564 * On success, return @blk's actual length.
565 * Otherwise, return -errno.
567 static int64_t create_file_fallback_truncate(BlockBackend *blk,
568 int64_t minimum_size, Error **errp)
570 Error *local_err = NULL;
571 int64_t size;
572 int ret;
574 ret = blk_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0,
575 &local_err);
576 if (ret < 0 && ret != -ENOTSUP) {
577 error_propagate(errp, local_err);
578 return ret;
581 size = blk_getlength(blk);
582 if (size < 0) {
583 error_free(local_err);
584 error_setg_errno(errp, -size,
585 "Failed to inquire the new image file's length");
586 return size;
589 if (size < minimum_size) {
590 /* Need to grow the image, but we failed to do that */
591 error_propagate(errp, local_err);
592 return -ENOTSUP;
595 error_free(local_err);
596 local_err = NULL;
598 return size;
602 * Helper function for bdrv_create_file_fallback(): Zero the first
603 * sector to remove any potentially pre-existing image header.
605 static int create_file_fallback_zero_first_sector(BlockBackend *blk,
606 int64_t current_size,
607 Error **errp)
609 int64_t bytes_to_clear;
610 int ret;
612 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
613 if (bytes_to_clear) {
614 ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
615 if (ret < 0) {
616 error_setg_errno(errp, -ret,
617 "Failed to clear the new image's first sector");
618 return ret;
622 return 0;
626 * Simple implementation of bdrv_co_create_opts for protocol drivers
627 * which only support creation via opening a file
628 * (usually existing raw storage device)
630 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
631 const char *filename,
632 QemuOpts *opts,
633 Error **errp)
635 BlockBackend *blk;
636 QDict *options;
637 int64_t size = 0;
638 char *buf = NULL;
639 PreallocMode prealloc;
640 Error *local_err = NULL;
641 int ret;
643 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
644 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
645 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
646 PREALLOC_MODE_OFF, &local_err);
647 g_free(buf);
648 if (local_err) {
649 error_propagate(errp, local_err);
650 return -EINVAL;
653 if (prealloc != PREALLOC_MODE_OFF) {
654 error_setg(errp, "Unsupported preallocation mode '%s'",
655 PreallocMode_str(prealloc));
656 return -ENOTSUP;
659 options = qdict_new();
660 qdict_put_str(options, "driver", drv->format_name);
662 blk = blk_new_open(filename, NULL, options,
663 BDRV_O_RDWR | BDRV_O_RESIZE, errp);
664 if (!blk) {
665 error_prepend(errp, "Protocol driver '%s' does not support image "
666 "creation, and opening the image failed: ",
667 drv->format_name);
668 return -EINVAL;
671 size = create_file_fallback_truncate(blk, size, errp);
672 if (size < 0) {
673 ret = size;
674 goto out;
677 ret = create_file_fallback_zero_first_sector(blk, size, errp);
678 if (ret < 0) {
679 goto out;
682 ret = 0;
683 out:
684 blk_unref(blk);
685 return ret;
688 int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
690 QemuOpts *protocol_opts;
691 BlockDriver *drv;
692 QDict *qdict;
693 int ret;
695 drv = bdrv_find_protocol(filename, true, errp);
696 if (drv == NULL) {
697 return -ENOENT;
700 if (!drv->create_opts) {
701 error_setg(errp, "Driver '%s' does not support image creation",
702 drv->format_name);
703 return -ENOTSUP;
707 * 'opts' contains a QemuOptsList with a combination of format and protocol
708 * default values.
710 * The format properly removes its options, but the default values remain
711 * in 'opts->list'. So if the protocol has options with the same name
712 * (e.g. rbd has 'cluster_size' as qcow2), it will see the default values
713 * of the format, since for overlapping options, the format wins.
715 * To avoid this issue, lets convert QemuOpts to QDict, in this way we take
716 * only the set options, and then convert it back to QemuOpts, using the
717 * create_opts of the protocol. So the new QemuOpts, will contain only the
718 * protocol defaults.
720 qdict = qemu_opts_to_qdict(opts, NULL);
721 protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp);
722 if (protocol_opts == NULL) {
723 ret = -EINVAL;
724 goto out;
727 ret = bdrv_create(drv, filename, protocol_opts, errp);
728 out:
729 qemu_opts_del(protocol_opts);
730 qobject_unref(qdict);
731 return ret;
734 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
736 Error *local_err = NULL;
737 int ret;
739 assert(bs != NULL);
741 if (!bs->drv) {
742 error_setg(errp, "Block node '%s' is not opened", bs->filename);
743 return -ENOMEDIUM;
746 if (!bs->drv->bdrv_co_delete_file) {
747 error_setg(errp, "Driver '%s' does not support image deletion",
748 bs->drv->format_name);
749 return -ENOTSUP;
752 ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
753 if (ret < 0) {
754 error_propagate(errp, local_err);
757 return ret;
760 void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs)
762 Error *local_err = NULL;
763 int ret;
765 if (!bs) {
766 return;
769 ret = bdrv_co_delete_file(bs, &local_err);
771 * ENOTSUP will happen if the block driver doesn't support
772 * the 'bdrv_co_delete_file' interface. This is a predictable
773 * scenario and shouldn't be reported back to the user.
775 if (ret == -ENOTSUP) {
776 error_free(local_err);
777 } else if (ret < 0) {
778 error_report_err(local_err);
783 * Try to get @bs's logical and physical block size.
784 * On success, store them in @bsz struct and return 0.
785 * On failure return -errno.
786 * @bs must not be empty.
788 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
790 BlockDriver *drv = bs->drv;
791 BlockDriverState *filtered = bdrv_filter_bs(bs);
793 if (drv && drv->bdrv_probe_blocksizes) {
794 return drv->bdrv_probe_blocksizes(bs, bsz);
795 } else if (filtered) {
796 return bdrv_probe_blocksizes(filtered, bsz);
799 return -ENOTSUP;
803 * Try to get @bs's geometry (cyls, heads, sectors).
804 * On success, store them in @geo struct and return 0.
805 * On failure return -errno.
806 * @bs must not be empty.
808 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
810 BlockDriver *drv = bs->drv;
811 BlockDriverState *filtered = bdrv_filter_bs(bs);
813 if (drv && drv->bdrv_probe_geometry) {
814 return drv->bdrv_probe_geometry(bs, geo);
815 } else if (filtered) {
816 return bdrv_probe_geometry(filtered, geo);
819 return -ENOTSUP;
823 * Create a uniquely-named empty temporary file.
824 * Return 0 upon success, otherwise a negative errno value.
826 int get_tmp_filename(char *filename, int size)
828 #ifdef _WIN32
829 char temp_dir[MAX_PATH];
830 /* GetTempFileName requires that its output buffer (4th param)
831 have length MAX_PATH or greater. */
832 assert(size >= MAX_PATH);
833 return (GetTempPath(MAX_PATH, temp_dir)
834 && GetTempFileName(temp_dir, "qem", 0, filename)
835 ? 0 : -GetLastError());
836 #else
837 int fd;
838 const char *tmpdir;
839 tmpdir = getenv("TMPDIR");
840 if (!tmpdir) {
841 tmpdir = "/var/tmp";
843 if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) {
844 return -EOVERFLOW;
846 fd = mkstemp(filename);
847 if (fd < 0) {
848 return -errno;
850 if (close(fd) != 0) {
851 unlink(filename);
852 return -errno;
854 return 0;
855 #endif
859 * Detect host devices. By convention, /dev/cdrom[N] is always
860 * recognized as a host CDROM.
862 static BlockDriver *find_hdev_driver(const char *filename)
864 int score_max = 0, score;
865 BlockDriver *drv = NULL, *d;
867 QLIST_FOREACH(d, &bdrv_drivers, list) {
868 if (d->bdrv_probe_device) {
869 score = d->bdrv_probe_device(filename);
870 if (score > score_max) {
871 score_max = score;
872 drv = d;
877 return drv;
880 static BlockDriver *bdrv_do_find_protocol(const char *protocol)
882 BlockDriver *drv1;
884 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
885 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
886 return drv1;
890 return NULL;
893 BlockDriver *bdrv_find_protocol(const char *filename,
894 bool allow_protocol_prefix,
895 Error **errp)
897 BlockDriver *drv1;
898 char protocol[128];
899 int len;
900 const char *p;
901 int i;
903 /* TODO Drivers without bdrv_file_open must be specified explicitly */
906 * XXX(hch): we really should not let host device detection
907 * override an explicit protocol specification, but moving this
908 * later breaks access to device names with colons in them.
909 * Thanks to the brain-dead persistent naming schemes on udev-
910 * based Linux systems those actually are quite common.
912 drv1 = find_hdev_driver(filename);
913 if (drv1) {
914 return drv1;
917 if (!path_has_protocol(filename) || !allow_protocol_prefix) {
918 return &bdrv_file;
921 p = strchr(filename, ':');
922 assert(p != NULL);
923 len = p - filename;
924 if (len > sizeof(protocol) - 1)
925 len = sizeof(protocol) - 1;
926 memcpy(protocol, filename, len);
927 protocol[len] = '\0';
929 drv1 = bdrv_do_find_protocol(protocol);
930 if (drv1) {
931 return drv1;
934 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
935 if (block_driver_modules[i].protocol_name &&
936 !strcmp(block_driver_modules[i].protocol_name, protocol)) {
937 block_module_load_one(block_driver_modules[i].library_name);
938 break;
942 drv1 = bdrv_do_find_protocol(protocol);
943 if (!drv1) {
944 error_setg(errp, "Unknown protocol '%s'", protocol);
946 return drv1;
950 * Guess image format by probing its contents.
951 * This is not a good idea when your image is raw (CVE-2008-2004), but
952 * we do it anyway for backward compatibility.
954 * @buf contains the image's first @buf_size bytes.
955 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
956 * but can be smaller if the image file is smaller)
957 * @filename is its filename.
959 * For all block drivers, call the bdrv_probe() method to get its
960 * probing score.
961 * Return the first block driver with the highest probing score.
963 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
964 const char *filename)
966 int score_max = 0, score;
967 BlockDriver *drv = NULL, *d;
969 QLIST_FOREACH(d, &bdrv_drivers, list) {
970 if (d->bdrv_probe) {
971 score = d->bdrv_probe(buf, buf_size, filename);
972 if (score > score_max) {
973 score_max = score;
974 drv = d;
979 return drv;
982 static int find_image_format(BlockBackend *file, const char *filename,
983 BlockDriver **pdrv, Error **errp)
985 BlockDriver *drv;
986 uint8_t buf[BLOCK_PROBE_BUF_SIZE];
987 int ret = 0;
989 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */
990 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
991 *pdrv = &bdrv_raw;
992 return ret;
995 ret = blk_pread(file, 0, buf, sizeof(buf));
996 if (ret < 0) {
997 error_setg_errno(errp, -ret, "Could not read image for determining its "
998 "format");
999 *pdrv = NULL;
1000 return ret;
1003 drv = bdrv_probe_all(buf, ret, filename);
1004 if (!drv) {
1005 error_setg(errp, "Could not determine image format: No compatible "
1006 "driver found");
1007 ret = -ENOENT;
1009 *pdrv = drv;
1010 return ret;
1014 * Set the current 'total_sectors' value
1015 * Return 0 on success, -errno on error.
1017 int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
1019 BlockDriver *drv = bs->drv;
1021 if (!drv) {
1022 return -ENOMEDIUM;
1025 /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
1026 if (bdrv_is_sg(bs))
1027 return 0;
1029 /* query actual device if possible, otherwise just trust the hint */
1030 if (drv->bdrv_getlength) {
1031 int64_t length = drv->bdrv_getlength(bs);
1032 if (length < 0) {
1033 return length;
1035 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
1038 bs->total_sectors = hint;
1040 if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) {
1041 return -EFBIG;
1044 return 0;
1048 * Combines a QDict of new block driver @options with any missing options taken
1049 * from @old_options, so that leaving out an option defaults to its old value.
1051 static void bdrv_join_options(BlockDriverState *bs, QDict *options,
1052 QDict *old_options)
1054 if (bs->drv && bs->drv->bdrv_join_options) {
1055 bs->drv->bdrv_join_options(options, old_options);
1056 } else {
1057 qdict_join(options, old_options, false);
1061 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
1062 int open_flags,
1063 Error **errp)
1065 Error *local_err = NULL;
1066 char *value = qemu_opt_get_del(opts, "detect-zeroes");
1067 BlockdevDetectZeroesOptions detect_zeroes =
1068 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
1069 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
1070 g_free(value);
1071 if (local_err) {
1072 error_propagate(errp, local_err);
1073 return detect_zeroes;
1076 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
1077 !(open_flags & BDRV_O_UNMAP))
1079 error_setg(errp, "setting detect-zeroes to unmap is not allowed "
1080 "without setting discard operation to unmap");
1083 return detect_zeroes;
1087 * Set open flags for aio engine
1089 * Return 0 on success, -1 if the engine specified is invalid
1091 int bdrv_parse_aio(const char *mode, int *flags)
1093 if (!strcmp(mode, "threads")) {
1094 /* do nothing, default */
1095 } else if (!strcmp(mode, "native")) {
1096 *flags |= BDRV_O_NATIVE_AIO;
1097 #ifdef CONFIG_LINUX_IO_URING
1098 } else if (!strcmp(mode, "io_uring")) {
1099 *flags |= BDRV_O_IO_URING;
1100 #endif
1101 } else {
1102 return -1;
1105 return 0;
1109 * Set open flags for a given discard mode
1111 * Return 0 on success, -1 if the discard mode was invalid.
1113 int bdrv_parse_discard_flags(const char *mode, int *flags)
1115 *flags &= ~BDRV_O_UNMAP;
1117 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
1118 /* do nothing */
1119 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
1120 *flags |= BDRV_O_UNMAP;
1121 } else {
1122 return -1;
1125 return 0;
1129 * Set open flags for a given cache mode
1131 * Return 0 on success, -1 if the cache mode was invalid.
1133 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
1135 *flags &= ~BDRV_O_CACHE_MASK;
1137 if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
1138 *writethrough = false;
1139 *flags |= BDRV_O_NOCACHE;
1140 } else if (!strcmp(mode, "directsync")) {
1141 *writethrough = true;
1142 *flags |= BDRV_O_NOCACHE;
1143 } else if (!strcmp(mode, "writeback")) {
1144 *writethrough = false;
1145 } else if (!strcmp(mode, "unsafe")) {
1146 *writethrough = false;
1147 *flags |= BDRV_O_NO_FLUSH;
1148 } else if (!strcmp(mode, "writethrough")) {
1149 *writethrough = true;
1150 } else {
1151 return -1;
1154 return 0;
1157 static char *bdrv_child_get_parent_desc(BdrvChild *c)
1159 BlockDriverState *parent = c->opaque;
1160 return g_strdup_printf("node '%s'", bdrv_get_node_name(parent));
1163 static void bdrv_child_cb_drained_begin(BdrvChild *child)
1165 BlockDriverState *bs = child->opaque;
1166 bdrv_do_drained_begin_quiesce(bs, NULL, false);
1169 static bool bdrv_child_cb_drained_poll(BdrvChild *child)
1171 BlockDriverState *bs = child->opaque;
1172 return bdrv_drain_poll(bs, false, NULL, false);
1175 static void bdrv_child_cb_drained_end(BdrvChild *child,
1176 int *drained_end_counter)
1178 BlockDriverState *bs = child->opaque;
1179 bdrv_drained_end_no_poll(bs, drained_end_counter);
1182 static int bdrv_child_cb_inactivate(BdrvChild *child)
1184 BlockDriverState *bs = child->opaque;
1185 assert(bs->open_flags & BDRV_O_INACTIVE);
1186 return 0;
1189 static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
1190 GSList **ignore, Error **errp)
1192 BlockDriverState *bs = child->opaque;
1193 return bdrv_can_set_aio_context(bs, ctx, ignore, errp);
1196 static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx,
1197 GSList **ignore)
1199 BlockDriverState *bs = child->opaque;
1200 return bdrv_set_aio_context_ignore(bs, ctx, ignore);
1204 * Returns the options and flags that a temporary snapshot should get, based on
1205 * the originally requested flags (the originally requested image will have
1206 * flags like a backing file)
1208 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
1209 int parent_flags, QDict *parent_options)
1211 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
1213 /* For temporary files, unconditional cache=unsafe is fine */
1214 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
1215 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
1217 /* Copy the read-only and discard options from the parent */
1218 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1219 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
1221 /* aio=native doesn't work for cache.direct=off, so disable it for the
1222 * temporary snapshot */
1223 *child_flags &= ~BDRV_O_NATIVE_AIO;
1226 static void bdrv_backing_attach(BdrvChild *c)
1228 BlockDriverState *parent = c->opaque;
1229 BlockDriverState *backing_hd = c->bs;
1231 assert(!parent->backing_blocker);
1232 error_setg(&parent->backing_blocker,
1233 "node is used as backing hd of '%s'",
1234 bdrv_get_device_or_node_name(parent));
1236 bdrv_refresh_filename(backing_hd);
1238 parent->open_flags &= ~BDRV_O_NO_BACKING;
1240 bdrv_op_block_all(backing_hd, parent->backing_blocker);
1241 /* Otherwise we won't be able to commit or stream */
1242 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
1243 parent->backing_blocker);
1244 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
1245 parent->backing_blocker);
1247 * We do backup in 3 ways:
1248 * 1. drive backup
1249 * The target bs is new opened, and the source is top BDS
1250 * 2. blockdev backup
1251 * Both the source and the target are top BDSes.
1252 * 3. internal backup(used for block replication)
1253 * Both the source and the target are backing file
1255 * In case 1 and 2, neither the source nor the target is the backing file.
1256 * In case 3, we will block the top BDS, so there is only one block job
1257 * for the top BDS and its backing chain.
1259 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
1260 parent->backing_blocker);
1261 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
1262 parent->backing_blocker);
1265 static void bdrv_backing_detach(BdrvChild *c)
1267 BlockDriverState *parent = c->opaque;
1269 assert(parent->backing_blocker);
1270 bdrv_op_unblock_all(c->bs, parent->backing_blocker);
1271 error_free(parent->backing_blocker);
1272 parent->backing_blocker = NULL;
1275 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
1276 const char *filename, Error **errp)
1278 BlockDriverState *parent = c->opaque;
1279 bool read_only = bdrv_is_read_only(parent);
1280 int ret;
1282 if (read_only) {
1283 ret = bdrv_reopen_set_read_only(parent, false, errp);
1284 if (ret < 0) {
1285 return ret;
1289 ret = bdrv_change_backing_file(parent, filename,
1290 base->drv ? base->drv->format_name : "",
1291 false);
1292 if (ret < 0) {
1293 error_setg_errno(errp, -ret, "Could not update backing file link");
1296 if (read_only) {
1297 bdrv_reopen_set_read_only(parent, true, NULL);
1300 return ret;
1304 * Returns the options and flags that a generic child of a BDS should
1305 * get, based on the given options and flags for the parent BDS.
1307 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
1308 int *child_flags, QDict *child_options,
1309 int parent_flags, QDict *parent_options)
1311 int flags = parent_flags;
1314 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL.
1315 * Generally, the question to answer is: Should this child be
1316 * format-probed by default?
1320 * Pure and non-filtered data children of non-format nodes should
1321 * be probed by default (even when the node itself has BDRV_O_PROTOCOL
1322 * set). This only affects a very limited set of drivers (namely
1323 * quorum and blkverify when this comment was written).
1324 * Force-clear BDRV_O_PROTOCOL then.
1326 if (!parent_is_format &&
1327 (role & BDRV_CHILD_DATA) &&
1328 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED)))
1330 flags &= ~BDRV_O_PROTOCOL;
1334 * All children of format nodes (except for COW children) and all
1335 * metadata children in general should never be format-probed.
1336 * Force-set BDRV_O_PROTOCOL then.
1338 if ((parent_is_format && !(role & BDRV_CHILD_COW)) ||
1339 (role & BDRV_CHILD_METADATA))
1341 flags |= BDRV_O_PROTOCOL;
1345 * If the cache mode isn't explicitly set, inherit direct and no-flush from
1346 * the parent.
1348 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
1349 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
1350 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
1352 if (role & BDRV_CHILD_COW) {
1353 /* backing files are opened read-only by default */
1354 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
1355 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
1356 } else {
1357 /* Inherit the read-only option from the parent if it's not set */
1358 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1359 qdict_copy_default(child_options, parent_options,
1360 BDRV_OPT_AUTO_READ_ONLY);
1364 * bdrv_co_pdiscard() respects unmap policy for the parent, so we
1365 * can default to enable it on lower layers regardless of the
1366 * parent option.
1368 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
1370 /* Clear flags that only apply to the top layer */
1371 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
1373 if (role & BDRV_CHILD_METADATA) {
1374 flags &= ~BDRV_O_NO_IO;
1376 if (role & BDRV_CHILD_COW) {
1377 flags &= ~BDRV_O_TEMPORARY;
1380 *child_flags = flags;
1383 static void bdrv_child_cb_attach(BdrvChild *child)
1385 BlockDriverState *bs = child->opaque;
1387 if (child->role & BDRV_CHILD_COW) {
1388 bdrv_backing_attach(child);
1391 bdrv_apply_subtree_drain(child, bs);
1394 static void bdrv_child_cb_detach(BdrvChild *child)
1396 BlockDriverState *bs = child->opaque;
1398 if (child->role & BDRV_CHILD_COW) {
1399 bdrv_backing_detach(child);
1402 bdrv_unapply_subtree_drain(child, bs);
1405 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
1406 const char *filename, Error **errp)
1408 if (c->role & BDRV_CHILD_COW) {
1409 return bdrv_backing_update_filename(c, base, filename, errp);
1411 return 0;
1414 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c)
1416 BlockDriverState *bs = c->opaque;
1418 return bdrv_get_aio_context(bs);
1421 const BdrvChildClass child_of_bds = {
1422 .parent_is_bds = true,
1423 .get_parent_desc = bdrv_child_get_parent_desc,
1424 .inherit_options = bdrv_inherited_options,
1425 .drained_begin = bdrv_child_cb_drained_begin,
1426 .drained_poll = bdrv_child_cb_drained_poll,
1427 .drained_end = bdrv_child_cb_drained_end,
1428 .attach = bdrv_child_cb_attach,
1429 .detach = bdrv_child_cb_detach,
1430 .inactivate = bdrv_child_cb_inactivate,
1431 .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
1432 .set_aio_ctx = bdrv_child_cb_set_aio_ctx,
1433 .update_filename = bdrv_child_cb_update_filename,
1434 .get_parent_aio_context = child_of_bds_get_parent_aio_context,
1437 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c)
1439 return c->klass->get_parent_aio_context(c);
1442 static int bdrv_open_flags(BlockDriverState *bs, int flags)
1444 int open_flags = flags;
1447 * Clear flags that are internal to the block layer before opening the
1448 * image.
1450 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
1452 return open_flags;
1455 static void update_flags_from_options(int *flags, QemuOpts *opts)
1457 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
1459 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
1460 *flags |= BDRV_O_NO_FLUSH;
1463 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
1464 *flags |= BDRV_O_NOCACHE;
1467 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
1468 *flags |= BDRV_O_RDWR;
1471 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
1472 *flags |= BDRV_O_AUTO_RDONLY;
1476 static void update_options_from_flags(QDict *options, int flags)
1478 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
1479 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
1481 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
1482 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
1483 flags & BDRV_O_NO_FLUSH);
1485 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
1486 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
1488 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
1489 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
1490 flags & BDRV_O_AUTO_RDONLY);
1494 static void bdrv_assign_node_name(BlockDriverState *bs,
1495 const char *node_name,
1496 Error **errp)
1498 char *gen_node_name = NULL;
1500 if (!node_name) {
1501 node_name = gen_node_name = id_generate(ID_BLOCK);
1502 } else if (!id_wellformed(node_name)) {
1504 * Check for empty string or invalid characters, but not if it is
1505 * generated (generated names use characters not available to the user)
1507 error_setg(errp, "Invalid node-name: '%s'", node_name);
1508 return;
1511 /* takes care of avoiding namespaces collisions */
1512 if (blk_by_name(node_name)) {
1513 error_setg(errp, "node-name=%s is conflicting with a device id",
1514 node_name);
1515 goto out;
1518 /* takes care of avoiding duplicates node names */
1519 if (bdrv_find_node(node_name)) {
1520 error_setg(errp, "Duplicate nodes with node-name='%s'", node_name);
1521 goto out;
1524 /* Make sure that the node name isn't truncated */
1525 if (strlen(node_name) >= sizeof(bs->node_name)) {
1526 error_setg(errp, "Node name too long");
1527 goto out;
1530 /* copy node name into the bs and insert it into the graph list */
1531 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
1532 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
1533 out:
1534 g_free(gen_node_name);
1537 static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv,
1538 const char *node_name, QDict *options,
1539 int open_flags, Error **errp)
1541 Error *local_err = NULL;
1542 int i, ret;
1544 bdrv_assign_node_name(bs, node_name, &local_err);
1545 if (local_err) {
1546 error_propagate(errp, local_err);
1547 return -EINVAL;
1550 bs->drv = drv;
1551 bs->opaque = g_malloc0(drv->instance_size);
1553 if (drv->bdrv_file_open) {
1554 assert(!drv->bdrv_needs_filename || bs->filename[0]);
1555 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
1556 } else if (drv->bdrv_open) {
1557 ret = drv->bdrv_open(bs, options, open_flags, &local_err);
1558 } else {
1559 ret = 0;
1562 if (ret < 0) {
1563 if (local_err) {
1564 error_propagate(errp, local_err);
1565 } else if (bs->filename[0]) {
1566 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
1567 } else {
1568 error_setg_errno(errp, -ret, "Could not open image");
1570 goto open_failed;
1573 ret = refresh_total_sectors(bs, bs->total_sectors);
1574 if (ret < 0) {
1575 error_setg_errno(errp, -ret, "Could not refresh total sector count");
1576 return ret;
1579 bdrv_refresh_limits(bs, NULL, &local_err);
1580 if (local_err) {
1581 error_propagate(errp, local_err);
1582 return -EINVAL;
1585 assert(bdrv_opt_mem_align(bs) != 0);
1586 assert(bdrv_min_mem_align(bs) != 0);
1587 assert(is_power_of_2(bs->bl.request_alignment));
1589 for (i = 0; i < bs->quiesce_counter; i++) {
1590 if (drv->bdrv_co_drain_begin) {
1591 drv->bdrv_co_drain_begin(bs);
1595 return 0;
1596 open_failed:
1597 bs->drv = NULL;
1598 if (bs->file != NULL) {
1599 bdrv_unref_child(bs, bs->file);
1600 bs->file = NULL;
1602 g_free(bs->opaque);
1603 bs->opaque = NULL;
1604 return ret;
1608 * Create and open a block node.
1610 * @options is a QDict of options to pass to the block drivers, or NULL for an
1611 * empty set of options. The reference to the QDict belongs to the block layer
1612 * after the call (even on failure), so if the caller intends to reuse the
1613 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
1615 BlockDriverState *bdrv_new_open_driver_opts(BlockDriver *drv,
1616 const char *node_name,
1617 QDict *options, int flags,
1618 Error **errp)
1620 BlockDriverState *bs;
1621 int ret;
1623 bs = bdrv_new();
1624 bs->open_flags = flags;
1625 bs->options = options ?: qdict_new();
1626 bs->explicit_options = qdict_clone_shallow(bs->options);
1627 bs->opaque = NULL;
1629 update_options_from_flags(bs->options, flags);
1631 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
1632 if (ret < 0) {
1633 qobject_unref(bs->explicit_options);
1634 bs->explicit_options = NULL;
1635 qobject_unref(bs->options);
1636 bs->options = NULL;
1637 bdrv_unref(bs);
1638 return NULL;
1641 return bs;
1644 /* Create and open a block node. */
1645 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
1646 int flags, Error **errp)
1648 return bdrv_new_open_driver_opts(drv, node_name, NULL, flags, errp);
1651 QemuOptsList bdrv_runtime_opts = {
1652 .name = "bdrv_common",
1653 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
1654 .desc = {
1656 .name = "node-name",
1657 .type = QEMU_OPT_STRING,
1658 .help = "Node name of the block device node",
1661 .name = "driver",
1662 .type = QEMU_OPT_STRING,
1663 .help = "Block driver to use for the node",
1666 .name = BDRV_OPT_CACHE_DIRECT,
1667 .type = QEMU_OPT_BOOL,
1668 .help = "Bypass software writeback cache on the host",
1671 .name = BDRV_OPT_CACHE_NO_FLUSH,
1672 .type = QEMU_OPT_BOOL,
1673 .help = "Ignore flush requests",
1676 .name = BDRV_OPT_READ_ONLY,
1677 .type = QEMU_OPT_BOOL,
1678 .help = "Node is opened in read-only mode",
1681 .name = BDRV_OPT_AUTO_READ_ONLY,
1682 .type = QEMU_OPT_BOOL,
1683 .help = "Node can become read-only if opening read-write fails",
1686 .name = "detect-zeroes",
1687 .type = QEMU_OPT_STRING,
1688 .help = "try to optimize zero writes (off, on, unmap)",
1691 .name = BDRV_OPT_DISCARD,
1692 .type = QEMU_OPT_STRING,
1693 .help = "discard operation (ignore/off, unmap/on)",
1696 .name = BDRV_OPT_FORCE_SHARE,
1697 .type = QEMU_OPT_BOOL,
1698 .help = "always accept other writers (default: off)",
1700 { /* end of list */ }
1704 QemuOptsList bdrv_create_opts_simple = {
1705 .name = "simple-create-opts",
1706 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head),
1707 .desc = {
1709 .name = BLOCK_OPT_SIZE,
1710 .type = QEMU_OPT_SIZE,
1711 .help = "Virtual disk size"
1714 .name = BLOCK_OPT_PREALLOC,
1715 .type = QEMU_OPT_STRING,
1716 .help = "Preallocation mode (allowed values: off)"
1718 { /* end of list */ }
1723 * Common part for opening disk images and files
1725 * Removes all processed options from *options.
1727 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
1728 QDict *options, Error **errp)
1730 int ret, open_flags;
1731 const char *filename;
1732 const char *driver_name = NULL;
1733 const char *node_name = NULL;
1734 const char *discard;
1735 QemuOpts *opts;
1736 BlockDriver *drv;
1737 Error *local_err = NULL;
1738 bool ro;
1740 assert(bs->file == NULL);
1741 assert(options != NULL && bs->options != options);
1743 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
1744 if (!qemu_opts_absorb_qdict(opts, options, errp)) {
1745 ret = -EINVAL;
1746 goto fail_opts;
1749 update_flags_from_options(&bs->open_flags, opts);
1751 driver_name = qemu_opt_get(opts, "driver");
1752 drv = bdrv_find_format(driver_name);
1753 assert(drv != NULL);
1755 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
1757 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
1758 error_setg(errp,
1759 BDRV_OPT_FORCE_SHARE
1760 "=on can only be used with read-only images");
1761 ret = -EINVAL;
1762 goto fail_opts;
1765 if (file != NULL) {
1766 bdrv_refresh_filename(blk_bs(file));
1767 filename = blk_bs(file)->filename;
1768 } else {
1770 * Caution: while qdict_get_try_str() is fine, getting
1771 * non-string types would require more care. When @options
1772 * come from -blockdev or blockdev_add, its members are typed
1773 * according to the QAPI schema, but when they come from
1774 * -drive, they're all QString.
1776 filename = qdict_get_try_str(options, "filename");
1779 if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
1780 error_setg(errp, "The '%s' block driver requires a file name",
1781 drv->format_name);
1782 ret = -EINVAL;
1783 goto fail_opts;
1786 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
1787 drv->format_name);
1789 ro = bdrv_is_read_only(bs);
1791 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, ro)) {
1792 if (!ro && bdrv_is_whitelisted(drv, true)) {
1793 ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
1794 } else {
1795 ret = -ENOTSUP;
1797 if (ret < 0) {
1798 error_setg(errp,
1799 !ro && bdrv_is_whitelisted(drv, true)
1800 ? "Driver '%s' can only be used for read-only devices"
1801 : "Driver '%s' is not whitelisted",
1802 drv->format_name);
1803 goto fail_opts;
1807 /* bdrv_new() and bdrv_close() make it so */
1808 assert(qatomic_read(&bs->copy_on_read) == 0);
1810 if (bs->open_flags & BDRV_O_COPY_ON_READ) {
1811 if (!ro) {
1812 bdrv_enable_copy_on_read(bs);
1813 } else {
1814 error_setg(errp, "Can't use copy-on-read on read-only device");
1815 ret = -EINVAL;
1816 goto fail_opts;
1820 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
1821 if (discard != NULL) {
1822 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
1823 error_setg(errp, "Invalid discard option");
1824 ret = -EINVAL;
1825 goto fail_opts;
1829 bs->detect_zeroes =
1830 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
1831 if (local_err) {
1832 error_propagate(errp, local_err);
1833 ret = -EINVAL;
1834 goto fail_opts;
1837 if (filename != NULL) {
1838 pstrcpy(bs->filename, sizeof(bs->filename), filename);
1839 } else {
1840 bs->filename[0] = '\0';
1842 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
1844 /* Open the image, either directly or using a protocol */
1845 open_flags = bdrv_open_flags(bs, bs->open_flags);
1846 node_name = qemu_opt_get(opts, "node-name");
1848 assert(!drv->bdrv_file_open || file == NULL);
1849 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
1850 if (ret < 0) {
1851 goto fail_opts;
1854 qemu_opts_del(opts);
1855 return 0;
1857 fail_opts:
1858 qemu_opts_del(opts);
1859 return ret;
1862 static QDict *parse_json_filename(const char *filename, Error **errp)
1864 QObject *options_obj;
1865 QDict *options;
1866 int ret;
1868 ret = strstart(filename, "json:", &filename);
1869 assert(ret);
1871 options_obj = qobject_from_json(filename, errp);
1872 if (!options_obj) {
1873 error_prepend(errp, "Could not parse the JSON options: ");
1874 return NULL;
1877 options = qobject_to(QDict, options_obj);
1878 if (!options) {
1879 qobject_unref(options_obj);
1880 error_setg(errp, "Invalid JSON object given");
1881 return NULL;
1884 qdict_flatten(options);
1886 return options;
1889 static void parse_json_protocol(QDict *options, const char **pfilename,
1890 Error **errp)
1892 QDict *json_options;
1893 Error *local_err = NULL;
1895 /* Parse json: pseudo-protocol */
1896 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
1897 return;
1900 json_options = parse_json_filename(*pfilename, &local_err);
1901 if (local_err) {
1902 error_propagate(errp, local_err);
1903 return;
1906 /* Options given in the filename have lower priority than options
1907 * specified directly */
1908 qdict_join(options, json_options, false);
1909 qobject_unref(json_options);
1910 *pfilename = NULL;
1914 * Fills in default options for opening images and converts the legacy
1915 * filename/flags pair to option QDict entries.
1916 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
1917 * block driver has been specified explicitly.
1919 static int bdrv_fill_options(QDict **options, const char *filename,
1920 int *flags, Error **errp)
1922 const char *drvname;
1923 bool protocol = *flags & BDRV_O_PROTOCOL;
1924 bool parse_filename = false;
1925 BlockDriver *drv = NULL;
1926 Error *local_err = NULL;
1929 * Caution: while qdict_get_try_str() is fine, getting non-string
1930 * types would require more care. When @options come from
1931 * -blockdev or blockdev_add, its members are typed according to
1932 * the QAPI schema, but when they come from -drive, they're all
1933 * QString.
1935 drvname = qdict_get_try_str(*options, "driver");
1936 if (drvname) {
1937 drv = bdrv_find_format(drvname);
1938 if (!drv) {
1939 error_setg(errp, "Unknown driver '%s'", drvname);
1940 return -ENOENT;
1942 /* If the user has explicitly specified the driver, this choice should
1943 * override the BDRV_O_PROTOCOL flag */
1944 protocol = drv->bdrv_file_open;
1947 if (protocol) {
1948 *flags |= BDRV_O_PROTOCOL;
1949 } else {
1950 *flags &= ~BDRV_O_PROTOCOL;
1953 /* Translate cache options from flags into options */
1954 update_options_from_flags(*options, *flags);
1956 /* Fetch the file name from the options QDict if necessary */
1957 if (protocol && filename) {
1958 if (!qdict_haskey(*options, "filename")) {
1959 qdict_put_str(*options, "filename", filename);
1960 parse_filename = true;
1961 } else {
1962 error_setg(errp, "Can't specify 'file' and 'filename' options at "
1963 "the same time");
1964 return -EINVAL;
1968 /* Find the right block driver */
1969 /* See cautionary note on accessing @options above */
1970 filename = qdict_get_try_str(*options, "filename");
1972 if (!drvname && protocol) {
1973 if (filename) {
1974 drv = bdrv_find_protocol(filename, parse_filename, errp);
1975 if (!drv) {
1976 return -EINVAL;
1979 drvname = drv->format_name;
1980 qdict_put_str(*options, "driver", drvname);
1981 } else {
1982 error_setg(errp, "Must specify either driver or file");
1983 return -EINVAL;
1987 assert(drv || !protocol);
1989 /* Driver-specific filename parsing */
1990 if (drv && drv->bdrv_parse_filename && parse_filename) {
1991 drv->bdrv_parse_filename(filename, *options, &local_err);
1992 if (local_err) {
1993 error_propagate(errp, local_err);
1994 return -EINVAL;
1997 if (!drv->bdrv_needs_filename) {
1998 qdict_del(*options, "filename");
2002 return 0;
2005 typedef struct BlockReopenQueueEntry {
2006 bool prepared;
2007 bool perms_checked;
2008 BDRVReopenState state;
2009 QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
2010 } BlockReopenQueueEntry;
2013 * Return the flags that @bs will have after the reopens in @q have
2014 * successfully completed. If @q is NULL (or @bs is not contained in @q),
2015 * return the current flags.
2017 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
2019 BlockReopenQueueEntry *entry;
2021 if (q != NULL) {
2022 QTAILQ_FOREACH(entry, q, entry) {
2023 if (entry->state.bs == bs) {
2024 return entry->state.flags;
2029 return bs->open_flags;
2032 /* Returns whether the image file can be written to after the reopen queue @q
2033 * has been successfully applied, or right now if @q is NULL. */
2034 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
2035 BlockReopenQueue *q)
2037 int flags = bdrv_reopen_get_flags(q, bs);
2039 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
2043 * Return whether the BDS can be written to. This is not necessarily
2044 * the same as !bdrv_is_read_only(bs), as inactivated images may not
2045 * be written to but do not count as read-only images.
2047 bool bdrv_is_writable(BlockDriverState *bs)
2049 return bdrv_is_writable_after_reopen(bs, NULL);
2052 static char *bdrv_child_user_desc(BdrvChild *c)
2054 return c->klass->get_parent_desc(c);
2058 * Check that @a allows everything that @b needs. @a and @b must reference same
2059 * child node.
2061 static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
2063 const char *child_bs_name;
2064 g_autofree char *a_user = NULL;
2065 g_autofree char *b_user = NULL;
2066 g_autofree char *perms = NULL;
2068 assert(a->bs);
2069 assert(a->bs == b->bs);
2071 if ((b->perm & a->shared_perm) == b->perm) {
2072 return true;
2075 child_bs_name = bdrv_get_node_name(b->bs);
2076 a_user = bdrv_child_user_desc(a);
2077 b_user = bdrv_child_user_desc(b);
2078 perms = bdrv_perm_names(b->perm & ~a->shared_perm);
2080 error_setg(errp, "Permission conflict on node '%s': permissions '%s' are "
2081 "both required by %s (uses node '%s' as '%s' child) and "
2082 "unshared by %s (uses node '%s' as '%s' child).",
2083 child_bs_name, perms,
2084 b_user, child_bs_name, b->name,
2085 a_user, child_bs_name, a->name);
2087 return false;
2090 static bool bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
2092 BdrvChild *a, *b;
2095 * During the loop we'll look at each pair twice. That's correct because
2096 * bdrv_a_allow_b() is asymmetric and we should check each pair in both
2097 * directions.
2099 QLIST_FOREACH(a, &bs->parents, next_parent) {
2100 QLIST_FOREACH(b, &bs->parents, next_parent) {
2101 if (a == b) {
2102 continue;
2105 if (!bdrv_a_allow_b(a, b, errp)) {
2106 return true;
2111 return false;
2114 static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
2115 BdrvChild *c, BdrvChildRole role,
2116 BlockReopenQueue *reopen_queue,
2117 uint64_t parent_perm, uint64_t parent_shared,
2118 uint64_t *nperm, uint64_t *nshared)
2120 assert(bs->drv && bs->drv->bdrv_child_perm);
2121 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
2122 parent_perm, parent_shared,
2123 nperm, nshared);
2124 /* TODO Take force_share from reopen_queue */
2125 if (child_bs && child_bs->force_share) {
2126 *nshared = BLK_PERM_ALL;
2131 * Adds the whole subtree of @bs (including @bs itself) to the @list (except for
2132 * nodes that are already in the @list, of course) so that final list is
2133 * topologically sorted. Return the result (GSList @list object is updated, so
2134 * don't use old reference after function call).
2136 * On function start @list must be already topologically sorted and for any node
2137 * in the @list the whole subtree of the node must be in the @list as well. The
2138 * simplest way to satisfy this criteria: use only result of
2139 * bdrv_topological_dfs() or NULL as @list parameter.
2141 static GSList *bdrv_topological_dfs(GSList *list, GHashTable *found,
2142 BlockDriverState *bs)
2144 BdrvChild *child;
2145 g_autoptr(GHashTable) local_found = NULL;
2147 if (!found) {
2148 assert(!list);
2149 found = local_found = g_hash_table_new(NULL, NULL);
2152 if (g_hash_table_contains(found, bs)) {
2153 return list;
2155 g_hash_table_add(found, bs);
2157 QLIST_FOREACH(child, &bs->children, next) {
2158 list = bdrv_topological_dfs(list, found, child->bs);
2161 return g_slist_prepend(list, bs);
2164 typedef struct BdrvChildSetPermState {
2165 BdrvChild *child;
2166 uint64_t old_perm;
2167 uint64_t old_shared_perm;
2168 } BdrvChildSetPermState;
2170 static void bdrv_child_set_perm_abort(void *opaque)
2172 BdrvChildSetPermState *s = opaque;
2174 s->child->perm = s->old_perm;
2175 s->child->shared_perm = s->old_shared_perm;
2178 static TransactionActionDrv bdrv_child_set_pem_drv = {
2179 .abort = bdrv_child_set_perm_abort,
2180 .clean = g_free,
2183 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm,
2184 uint64_t shared, Transaction *tran)
2186 BdrvChildSetPermState *s = g_new(BdrvChildSetPermState, 1);
2188 *s = (BdrvChildSetPermState) {
2189 .child = c,
2190 .old_perm = c->perm,
2191 .old_shared_perm = c->shared_perm,
2194 c->perm = perm;
2195 c->shared_perm = shared;
2197 tran_add(tran, &bdrv_child_set_pem_drv, s);
2200 static void bdrv_drv_set_perm_commit(void *opaque)
2202 BlockDriverState *bs = opaque;
2203 uint64_t cumulative_perms, cumulative_shared_perms;
2205 if (bs->drv->bdrv_set_perm) {
2206 bdrv_get_cumulative_perm(bs, &cumulative_perms,
2207 &cumulative_shared_perms);
2208 bs->drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
2212 static void bdrv_drv_set_perm_abort(void *opaque)
2214 BlockDriverState *bs = opaque;
2216 if (bs->drv->bdrv_abort_perm_update) {
2217 bs->drv->bdrv_abort_perm_update(bs);
2221 TransactionActionDrv bdrv_drv_set_perm_drv = {
2222 .abort = bdrv_drv_set_perm_abort,
2223 .commit = bdrv_drv_set_perm_commit,
2226 static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm,
2227 uint64_t shared_perm, Transaction *tran,
2228 Error **errp)
2230 if (!bs->drv) {
2231 return 0;
2234 if (bs->drv->bdrv_check_perm) {
2235 int ret = bs->drv->bdrv_check_perm(bs, perm, shared_perm, errp);
2236 if (ret < 0) {
2237 return ret;
2241 if (tran) {
2242 tran_add(tran, &bdrv_drv_set_perm_drv, bs);
2245 return 0;
2248 typedef struct BdrvReplaceChildState {
2249 BdrvChild *child;
2250 BlockDriverState *old_bs;
2251 } BdrvReplaceChildState;
2253 static void bdrv_replace_child_commit(void *opaque)
2255 BdrvReplaceChildState *s = opaque;
2257 bdrv_unref(s->old_bs);
2260 static void bdrv_replace_child_abort(void *opaque)
2262 BdrvReplaceChildState *s = opaque;
2263 BlockDriverState *new_bs = s->child->bs;
2265 /* old_bs reference is transparently moved from @s to @s->child */
2266 bdrv_replace_child_noperm(s->child, s->old_bs);
2267 bdrv_unref(new_bs);
2270 static TransactionActionDrv bdrv_replace_child_drv = {
2271 .commit = bdrv_replace_child_commit,
2272 .abort = bdrv_replace_child_abort,
2273 .clean = g_free,
2277 * bdrv_replace_child_tran
2279 * Note: real unref of old_bs is done only on commit.
2281 * The function doesn't update permissions, caller is responsible for this.
2283 static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
2284 Transaction *tran)
2286 BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
2287 *s = (BdrvReplaceChildState) {
2288 .child = child,
2289 .old_bs = child->bs,
2291 tran_add(tran, &bdrv_replace_child_drv, s);
2293 if (new_bs) {
2294 bdrv_ref(new_bs);
2296 bdrv_replace_child_noperm(child, new_bs);
2297 /* old_bs reference is transparently moved from @child to @s */
2301 * Refresh permissions in @bs subtree. The function is intended to be called
2302 * after some graph modification that was done without permission update.
2304 static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
2305 Transaction *tran, Error **errp)
2307 BlockDriver *drv = bs->drv;
2308 BdrvChild *c;
2309 int ret;
2310 uint64_t cumulative_perms, cumulative_shared_perms;
2312 bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms);
2314 /* Write permissions never work with read-only images */
2315 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2316 !bdrv_is_writable_after_reopen(bs, q))
2318 if (!bdrv_is_writable_after_reopen(bs, NULL)) {
2319 error_setg(errp, "Block node is read-only");
2320 } else {
2321 error_setg(errp, "Read-only block node '%s' cannot support "
2322 "read-write users", bdrv_get_node_name(bs));
2325 return -EPERM;
2329 * Unaligned requests will automatically be aligned to bl.request_alignment
2330 * and without RESIZE we can't extend requests to write to space beyond the
2331 * end of the image, so it's required that the image size is aligned.
2333 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2334 !(cumulative_perms & BLK_PERM_RESIZE))
2336 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) {
2337 error_setg(errp, "Cannot get 'write' permission without 'resize': "
2338 "Image size is not a multiple of request "
2339 "alignment");
2340 return -EPERM;
2344 /* Check this node */
2345 if (!drv) {
2346 return 0;
2349 ret = bdrv_drv_set_perm(bs, cumulative_perms, cumulative_shared_perms, tran,
2350 errp);
2351 if (ret < 0) {
2352 return ret;
2355 /* Drivers that never have children can omit .bdrv_child_perm() */
2356 if (!drv->bdrv_child_perm) {
2357 assert(QLIST_EMPTY(&bs->children));
2358 return 0;
2361 /* Check all children */
2362 QLIST_FOREACH(c, &bs->children, next) {
2363 uint64_t cur_perm, cur_shared;
2365 bdrv_child_perm(bs, c->bs, c, c->role, q,
2366 cumulative_perms, cumulative_shared_perms,
2367 &cur_perm, &cur_shared);
2368 bdrv_child_set_perm(c, cur_perm, cur_shared, tran);
2371 return 0;
2374 static int bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q,
2375 Transaction *tran, Error **errp)
2377 int ret;
2378 BlockDriverState *bs;
2380 for ( ; list; list = list->next) {
2381 bs = list->data;
2383 if (bdrv_parent_perms_conflict(bs, errp)) {
2384 return -EINVAL;
2387 ret = bdrv_node_refresh_perm(bs, q, tran, errp);
2388 if (ret < 0) {
2389 return ret;
2393 return 0;
2396 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
2397 uint64_t *shared_perm)
2399 BdrvChild *c;
2400 uint64_t cumulative_perms = 0;
2401 uint64_t cumulative_shared_perms = BLK_PERM_ALL;
2403 QLIST_FOREACH(c, &bs->parents, next_parent) {
2404 cumulative_perms |= c->perm;
2405 cumulative_shared_perms &= c->shared_perm;
2408 *perm = cumulative_perms;
2409 *shared_perm = cumulative_shared_perms;
2412 char *bdrv_perm_names(uint64_t perm)
2414 struct perm_name {
2415 uint64_t perm;
2416 const char *name;
2417 } permissions[] = {
2418 { BLK_PERM_CONSISTENT_READ, "consistent read" },
2419 { BLK_PERM_WRITE, "write" },
2420 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
2421 { BLK_PERM_RESIZE, "resize" },
2422 { BLK_PERM_GRAPH_MOD, "change children" },
2423 { 0, NULL }
2426 GString *result = g_string_sized_new(30);
2427 struct perm_name *p;
2429 for (p = permissions; p->name; p++) {
2430 if (perm & p->perm) {
2431 if (result->len > 0) {
2432 g_string_append(result, ", ");
2434 g_string_append(result, p->name);
2438 return g_string_free(result, FALSE);
2442 static int bdrv_refresh_perms(BlockDriverState *bs, Error **errp)
2444 int ret;
2445 Transaction *tran = tran_new();
2446 g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs);
2448 ret = bdrv_list_refresh_perms(list, NULL, tran, errp);
2449 tran_finalize(tran, ret);
2451 return ret;
2454 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
2455 Error **errp)
2457 Error *local_err = NULL;
2458 Transaction *tran = tran_new();
2459 int ret;
2461 bdrv_child_set_perm(c, perm, shared, tran);
2463 ret = bdrv_refresh_perms(c->bs, &local_err);
2465 tran_finalize(tran, ret);
2467 if (ret < 0) {
2468 if ((perm & ~c->perm) || (c->shared_perm & ~shared)) {
2469 /* tighten permissions */
2470 error_propagate(errp, local_err);
2471 } else {
2473 * Our caller may intend to only loosen restrictions and
2474 * does not expect this function to fail. Errors are not
2475 * fatal in such a case, so we can just hide them from our
2476 * caller.
2478 error_free(local_err);
2479 ret = 0;
2483 return ret;
2486 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
2488 uint64_t parent_perms, parent_shared;
2489 uint64_t perms, shared;
2491 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
2492 bdrv_child_perm(bs, c->bs, c, c->role, NULL,
2493 parent_perms, parent_shared, &perms, &shared);
2495 return bdrv_child_try_set_perm(c, perms, shared, errp);
2499 * Default implementation for .bdrv_child_perm() for block filters:
2500 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the
2501 * filtered child.
2503 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
2504 BdrvChildRole role,
2505 BlockReopenQueue *reopen_queue,
2506 uint64_t perm, uint64_t shared,
2507 uint64_t *nperm, uint64_t *nshared)
2509 *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
2510 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
2513 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c,
2514 BdrvChildRole role,
2515 BlockReopenQueue *reopen_queue,
2516 uint64_t perm, uint64_t shared,
2517 uint64_t *nperm, uint64_t *nshared)
2519 assert(role & BDRV_CHILD_COW);
2522 * We want consistent read from backing files if the parent needs it.
2523 * No other operations are performed on backing files.
2525 perm &= BLK_PERM_CONSISTENT_READ;
2528 * If the parent can deal with changing data, we're okay with a
2529 * writable and resizable backing file.
2530 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too?
2532 if (shared & BLK_PERM_WRITE) {
2533 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
2534 } else {
2535 shared = 0;
2538 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD |
2539 BLK_PERM_WRITE_UNCHANGED;
2541 if (bs->open_flags & BDRV_O_INACTIVE) {
2542 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2545 *nperm = perm;
2546 *nshared = shared;
2549 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c,
2550 BdrvChildRole role,
2551 BlockReopenQueue *reopen_queue,
2552 uint64_t perm, uint64_t shared,
2553 uint64_t *nperm, uint64_t *nshared)
2555 int flags;
2557 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA));
2559 flags = bdrv_reopen_get_flags(reopen_queue, bs);
2562 * Apart from the modifications below, the same permissions are
2563 * forwarded and left alone as for filters
2565 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2566 perm, shared, &perm, &shared);
2568 if (role & BDRV_CHILD_METADATA) {
2569 /* Format drivers may touch metadata even if the guest doesn't write */
2570 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
2571 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2575 * bs->file always needs to be consistent because of the
2576 * metadata. We can never allow other users to resize or write
2577 * to it.
2579 if (!(flags & BDRV_O_NO_IO)) {
2580 perm |= BLK_PERM_CONSISTENT_READ;
2582 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
2585 if (role & BDRV_CHILD_DATA) {
2587 * Technically, everything in this block is a subset of the
2588 * BDRV_CHILD_METADATA path taken above, and so this could
2589 * be an "else if" branch. However, that is not obvious, and
2590 * this function is not performance critical, therefore we let
2591 * this be an independent "if".
2595 * We cannot allow other users to resize the file because the
2596 * format driver might have some assumptions about the size
2597 * (e.g. because it is stored in metadata, or because the file
2598 * is split into fixed-size data files).
2600 shared &= ~BLK_PERM_RESIZE;
2603 * WRITE_UNCHANGED often cannot be performed as such on the
2604 * data file. For example, the qcow2 driver may still need to
2605 * write copied clusters on copy-on-read.
2607 if (perm & BLK_PERM_WRITE_UNCHANGED) {
2608 perm |= BLK_PERM_WRITE;
2612 * If the data file is written to, the format driver may
2613 * expect to be able to resize it by writing beyond the EOF.
2615 if (perm & BLK_PERM_WRITE) {
2616 perm |= BLK_PERM_RESIZE;
2620 if (bs->open_flags & BDRV_O_INACTIVE) {
2621 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2624 *nperm = perm;
2625 *nshared = shared;
2628 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
2629 BdrvChildRole role, BlockReopenQueue *reopen_queue,
2630 uint64_t perm, uint64_t shared,
2631 uint64_t *nperm, uint64_t *nshared)
2633 if (role & BDRV_CHILD_FILTERED) {
2634 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
2635 BDRV_CHILD_COW)));
2636 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2637 perm, shared, nperm, nshared);
2638 } else if (role & BDRV_CHILD_COW) {
2639 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA)));
2640 bdrv_default_perms_for_cow(bs, c, role, reopen_queue,
2641 perm, shared, nperm, nshared);
2642 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) {
2643 bdrv_default_perms_for_storage(bs, c, role, reopen_queue,
2644 perm, shared, nperm, nshared);
2645 } else {
2646 g_assert_not_reached();
2650 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
2652 static const uint64_t permissions[] = {
2653 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ,
2654 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE,
2655 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED,
2656 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE,
2657 [BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD,
2660 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX);
2661 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1);
2663 assert(qapi_perm < BLOCK_PERMISSION__MAX);
2665 return permissions[qapi_perm];
2668 static void bdrv_replace_child_noperm(BdrvChild *child,
2669 BlockDriverState *new_bs)
2671 BlockDriverState *old_bs = child->bs;
2672 int new_bs_quiesce_counter;
2673 int drain_saldo;
2675 assert(!child->frozen);
2677 if (old_bs && new_bs) {
2678 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
2681 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0);
2682 drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter;
2685 * If the new child node is drained but the old one was not, flush
2686 * all outstanding requests to the old child node.
2688 while (drain_saldo > 0 && child->klass->drained_begin) {
2689 bdrv_parent_drained_begin_single(child, true);
2690 drain_saldo--;
2693 if (old_bs) {
2694 /* Detach first so that the recursive drain sections coming from @child
2695 * are already gone and we only end the drain sections that came from
2696 * elsewhere. */
2697 if (child->klass->detach) {
2698 child->klass->detach(child);
2700 QLIST_REMOVE(child, next_parent);
2703 child->bs = new_bs;
2705 if (new_bs) {
2706 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
2709 * Detaching the old node may have led to the new node's
2710 * quiesce_counter having been decreased. Not a problem, we
2711 * just need to recognize this here and then invoke
2712 * drained_end appropriately more often.
2714 assert(new_bs->quiesce_counter <= new_bs_quiesce_counter);
2715 drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter;
2717 /* Attach only after starting new drained sections, so that recursive
2718 * drain sections coming from @child don't get an extra .drained_begin
2719 * callback. */
2720 if (child->klass->attach) {
2721 child->klass->attach(child);
2726 * If the old child node was drained but the new one is not, allow
2727 * requests to come in only after the new node has been attached.
2729 while (drain_saldo < 0 && child->klass->drained_end) {
2730 bdrv_parent_drained_end_single(child);
2731 drain_saldo++;
2735 static void bdrv_child_free(void *opaque)
2737 BdrvChild *c = opaque;
2739 g_free(c->name);
2740 g_free(c);
2743 static void bdrv_remove_empty_child(BdrvChild *child)
2745 assert(!child->bs);
2746 QLIST_SAFE_REMOVE(child, next);
2747 bdrv_child_free(child);
2750 typedef struct BdrvAttachChildCommonState {
2751 BdrvChild **child;
2752 AioContext *old_parent_ctx;
2753 AioContext *old_child_ctx;
2754 } BdrvAttachChildCommonState;
2756 static void bdrv_attach_child_common_abort(void *opaque)
2758 BdrvAttachChildCommonState *s = opaque;
2759 BdrvChild *child = *s->child;
2760 BlockDriverState *bs = child->bs;
2762 bdrv_replace_child_noperm(child, NULL);
2764 if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
2765 bdrv_try_set_aio_context(bs, s->old_child_ctx, &error_abort);
2768 if (bdrv_child_get_parent_aio_context(child) != s->old_parent_ctx) {
2769 GSList *ignore = g_slist_prepend(NULL, child);
2771 child->klass->can_set_aio_ctx(child, s->old_parent_ctx, &ignore,
2772 &error_abort);
2773 g_slist_free(ignore);
2774 ignore = g_slist_prepend(NULL, child);
2775 child->klass->set_aio_ctx(child, s->old_parent_ctx, &ignore);
2777 g_slist_free(ignore);
2780 bdrv_unref(bs);
2781 bdrv_remove_empty_child(child);
2782 *s->child = NULL;
2785 static TransactionActionDrv bdrv_attach_child_common_drv = {
2786 .abort = bdrv_attach_child_common_abort,
2787 .clean = g_free,
2791 * Common part of attaching bdrv child to bs or to blk or to job
2793 * Resulting new child is returned through @child.
2794 * At start *@child must be NULL.
2795 * @child is saved to a new entry of @tran, so that *@child could be reverted to
2796 * NULL on abort(). So referenced variable must live at least until transaction
2797 * end.
2799 * Function doesn't update permissions, caller is responsible for this.
2801 static int bdrv_attach_child_common(BlockDriverState *child_bs,
2802 const char *child_name,
2803 const BdrvChildClass *child_class,
2804 BdrvChildRole child_role,
2805 uint64_t perm, uint64_t shared_perm,
2806 void *opaque, BdrvChild **child,
2807 Transaction *tran, Error **errp)
2809 BdrvChild *new_child;
2810 AioContext *parent_ctx;
2811 AioContext *child_ctx = bdrv_get_aio_context(child_bs);
2813 assert(child);
2814 assert(*child == NULL);
2815 assert(child_class->get_parent_desc);
2817 new_child = g_new(BdrvChild, 1);
2818 *new_child = (BdrvChild) {
2819 .bs = NULL,
2820 .name = g_strdup(child_name),
2821 .klass = child_class,
2822 .role = child_role,
2823 .perm = perm,
2824 .shared_perm = shared_perm,
2825 .opaque = opaque,
2829 * If the AioContexts don't match, first try to move the subtree of
2830 * child_bs into the AioContext of the new parent. If this doesn't work,
2831 * try moving the parent into the AioContext of child_bs instead.
2833 parent_ctx = bdrv_child_get_parent_aio_context(new_child);
2834 if (child_ctx != parent_ctx) {
2835 Error *local_err = NULL;
2836 int ret = bdrv_try_set_aio_context(child_bs, parent_ctx, &local_err);
2838 if (ret < 0 && child_class->can_set_aio_ctx) {
2839 GSList *ignore = g_slist_prepend(NULL, new_child);
2840 if (child_class->can_set_aio_ctx(new_child, child_ctx, &ignore,
2841 NULL))
2843 error_free(local_err);
2844 ret = 0;
2845 g_slist_free(ignore);
2846 ignore = g_slist_prepend(NULL, new_child);
2847 child_class->set_aio_ctx(new_child, child_ctx, &ignore);
2849 g_slist_free(ignore);
2852 if (ret < 0) {
2853 error_propagate(errp, local_err);
2854 bdrv_remove_empty_child(new_child);
2855 return ret;
2859 bdrv_ref(child_bs);
2860 bdrv_replace_child_noperm(new_child, child_bs);
2862 *child = new_child;
2864 BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
2865 *s = (BdrvAttachChildCommonState) {
2866 .child = child,
2867 .old_parent_ctx = parent_ctx,
2868 .old_child_ctx = child_ctx,
2870 tran_add(tran, &bdrv_attach_child_common_drv, s);
2872 return 0;
2876 * Variable referenced by @child must live at least until transaction end.
2877 * (see bdrv_attach_child_common() doc for details)
2879 * Function doesn't update permissions, caller is responsible for this.
2881 static int bdrv_attach_child_noperm(BlockDriverState *parent_bs,
2882 BlockDriverState *child_bs,
2883 const char *child_name,
2884 const BdrvChildClass *child_class,
2885 BdrvChildRole child_role,
2886 BdrvChild **child,
2887 Transaction *tran,
2888 Error **errp)
2890 int ret;
2891 uint64_t perm, shared_perm;
2893 assert(parent_bs->drv);
2895 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
2896 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
2897 perm, shared_perm, &perm, &shared_perm);
2899 ret = bdrv_attach_child_common(child_bs, child_name, child_class,
2900 child_role, perm, shared_perm, parent_bs,
2901 child, tran, errp);
2902 if (ret < 0) {
2903 return ret;
2906 QLIST_INSERT_HEAD(&parent_bs->children, *child, next);
2908 * child is removed in bdrv_attach_child_common_abort(), so don't care to
2909 * abort this change separately.
2912 return 0;
2915 static void bdrv_detach_child(BdrvChild *child)
2917 BlockDriverState *old_bs = child->bs;
2919 bdrv_replace_child_noperm(child, NULL);
2920 bdrv_remove_empty_child(child);
2922 if (old_bs) {
2924 * Update permissions for old node. We're just taking a parent away, so
2925 * we're loosening restrictions. Errors of permission update are not
2926 * fatal in this case, ignore them.
2928 bdrv_refresh_perms(old_bs, NULL);
2931 * When the parent requiring a non-default AioContext is removed, the
2932 * node moves back to the main AioContext
2934 bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL);
2939 * This function steals the reference to child_bs from the caller.
2940 * That reference is later dropped by bdrv_root_unref_child().
2942 * On failure NULL is returned, errp is set and the reference to
2943 * child_bs is also dropped.
2945 * The caller must hold the AioContext lock @child_bs, but not that of @ctx
2946 * (unless @child_bs is already in @ctx).
2948 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
2949 const char *child_name,
2950 const BdrvChildClass *child_class,
2951 BdrvChildRole child_role,
2952 uint64_t perm, uint64_t shared_perm,
2953 void *opaque, Error **errp)
2955 int ret;
2956 BdrvChild *child = NULL;
2957 Transaction *tran = tran_new();
2959 ret = bdrv_attach_child_common(child_bs, child_name, child_class,
2960 child_role, perm, shared_perm, opaque,
2961 &child, tran, errp);
2962 if (ret < 0) {
2963 goto out;
2966 ret = bdrv_refresh_perms(child_bs, errp);
2968 out:
2969 tran_finalize(tran, ret);
2970 /* child is unset on failure by bdrv_attach_child_common_abort() */
2971 assert((ret < 0) == !child);
2973 bdrv_unref(child_bs);
2974 return child;
2978 * This function transfers the reference to child_bs from the caller
2979 * to parent_bs. That reference is later dropped by parent_bs on
2980 * bdrv_close() or if someone calls bdrv_unref_child().
2982 * On failure NULL is returned, errp is set and the reference to
2983 * child_bs is also dropped.
2985 * If @parent_bs and @child_bs are in different AioContexts, the caller must
2986 * hold the AioContext lock for @child_bs, but not for @parent_bs.
2988 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
2989 BlockDriverState *child_bs,
2990 const char *child_name,
2991 const BdrvChildClass *child_class,
2992 BdrvChildRole child_role,
2993 Error **errp)
2995 int ret;
2996 BdrvChild *child = NULL;
2997 Transaction *tran = tran_new();
2999 ret = bdrv_attach_child_noperm(parent_bs, child_bs, child_name, child_class,
3000 child_role, &child, tran, errp);
3001 if (ret < 0) {
3002 goto out;
3005 ret = bdrv_refresh_perms(parent_bs, errp);
3006 if (ret < 0) {
3007 goto out;
3010 out:
3011 tran_finalize(tran, ret);
3012 /* child is unset on failure by bdrv_attach_child_common_abort() */
3013 assert((ret < 0) == !child);
3015 bdrv_unref(child_bs);
3017 return child;
3020 /* Callers must ensure that child->frozen is false. */
3021 void bdrv_root_unref_child(BdrvChild *child)
3023 BlockDriverState *child_bs;
3025 child_bs = child->bs;
3026 bdrv_detach_child(child);
3027 bdrv_unref(child_bs);
3030 typedef struct BdrvSetInheritsFrom {
3031 BlockDriverState *bs;
3032 BlockDriverState *old_inherits_from;
3033 } BdrvSetInheritsFrom;
3035 static void bdrv_set_inherits_from_abort(void *opaque)
3037 BdrvSetInheritsFrom *s = opaque;
3039 s->bs->inherits_from = s->old_inherits_from;
3042 static TransactionActionDrv bdrv_set_inherits_from_drv = {
3043 .abort = bdrv_set_inherits_from_abort,
3044 .clean = g_free,
3047 /* @tran is allowed to be NULL. In this case no rollback is possible */
3048 static void bdrv_set_inherits_from(BlockDriverState *bs,
3049 BlockDriverState *new_inherits_from,
3050 Transaction *tran)
3052 if (tran) {
3053 BdrvSetInheritsFrom *s = g_new(BdrvSetInheritsFrom, 1);
3055 *s = (BdrvSetInheritsFrom) {
3056 .bs = bs,
3057 .old_inherits_from = bs->inherits_from,
3060 tran_add(tran, &bdrv_set_inherits_from_drv, s);
3063 bs->inherits_from = new_inherits_from;
3067 * Clear all inherits_from pointers from children and grandchildren of
3068 * @root that point to @root, where necessary.
3069 * @tran is allowed to be NULL. In this case no rollback is possible
3071 static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child,
3072 Transaction *tran)
3074 BdrvChild *c;
3076 if (child->bs->inherits_from == root) {
3078 * Remove inherits_from only when the last reference between root and
3079 * child->bs goes away.
3081 QLIST_FOREACH(c, &root->children, next) {
3082 if (c != child && c->bs == child->bs) {
3083 break;
3086 if (c == NULL) {
3087 bdrv_set_inherits_from(child->bs, NULL, tran);
3091 QLIST_FOREACH(c, &child->bs->children, next) {
3092 bdrv_unset_inherits_from(root, c, tran);
3096 /* Callers must ensure that child->frozen is false. */
3097 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
3099 if (child == NULL) {
3100 return;
3103 bdrv_unset_inherits_from(parent, child, NULL);
3104 bdrv_root_unref_child(child);
3108 static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
3110 BdrvChild *c;
3111 QLIST_FOREACH(c, &bs->parents, next_parent) {
3112 if (c->klass->change_media) {
3113 c->klass->change_media(c, load);
3118 /* Return true if you can reach parent going through child->inherits_from
3119 * recursively. If parent or child are NULL, return false */
3120 static bool bdrv_inherits_from_recursive(BlockDriverState *child,
3121 BlockDriverState *parent)
3123 while (child && child != parent) {
3124 child = child->inherits_from;
3127 return child != NULL;
3131 * Return the BdrvChildRole for @bs's backing child. bs->backing is
3132 * mostly used for COW backing children (role = COW), but also for
3133 * filtered children (role = FILTERED | PRIMARY).
3135 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
3137 if (bs->drv && bs->drv->is_filter) {
3138 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
3139 } else {
3140 return BDRV_CHILD_COW;
3145 * Sets the bs->backing or bs->file link of a BDS. A new reference is created;
3146 * callers which don't need their own reference any more must call bdrv_unref().
3148 * Function doesn't update permissions, caller is responsible for this.
3150 static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
3151 BlockDriverState *child_bs,
3152 bool is_backing,
3153 Transaction *tran, Error **errp)
3155 int ret = 0;
3156 bool update_inherits_from =
3157 bdrv_inherits_from_recursive(child_bs, parent_bs);
3158 BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file;
3159 BdrvChildRole role;
3161 if (!parent_bs->drv) {
3163 * Node without drv is an object without a class :/. TODO: finally fix
3164 * qcow2 driver to never clear bs->drv and implement format corruption
3165 * handling in other way.
3167 error_setg(errp, "Node corrupted");
3168 return -EINVAL;
3171 if (child && child->frozen) {
3172 error_setg(errp, "Cannot change frozen '%s' link from '%s' to '%s'",
3173 child->name, parent_bs->node_name, child->bs->node_name);
3174 return -EPERM;
3177 if (is_backing && !parent_bs->drv->is_filter &&
3178 !parent_bs->drv->supports_backing)
3180 error_setg(errp, "Driver '%s' of node '%s' does not support backing "
3181 "files", parent_bs->drv->format_name, parent_bs->node_name);
3182 return -EINVAL;
3185 if (parent_bs->drv->is_filter) {
3186 role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
3187 } else if (is_backing) {
3188 role = BDRV_CHILD_COW;
3189 } else {
3191 * We only can use same role as it is in existing child. We don't have
3192 * infrastructure to determine role of file child in generic way
3194 if (!child) {
3195 error_setg(errp, "Cannot set file child to format node without "
3196 "file child");
3197 return -EINVAL;
3199 role = child->role;
3202 if (child) {
3203 bdrv_unset_inherits_from(parent_bs, child, tran);
3204 bdrv_remove_file_or_backing_child(parent_bs, child, tran);
3207 if (!child_bs) {
3208 goto out;
3211 ret = bdrv_attach_child_noperm(parent_bs, child_bs,
3212 is_backing ? "backing" : "file",
3213 &child_of_bds, role,
3214 is_backing ? &parent_bs->backing :
3215 &parent_bs->file,
3216 tran, errp);
3217 if (ret < 0) {
3218 return ret;
3223 * If inherits_from pointed recursively to bs then let's update it to
3224 * point directly to bs (else it will become NULL).
3226 if (update_inherits_from) {
3227 bdrv_set_inherits_from(child_bs, parent_bs, tran);
3230 out:
3231 bdrv_refresh_limits(parent_bs, tran, NULL);
3233 return 0;
3236 static int bdrv_set_backing_noperm(BlockDriverState *bs,
3237 BlockDriverState *backing_hd,
3238 Transaction *tran, Error **errp)
3240 return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp);
3243 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
3244 Error **errp)
3246 int ret;
3247 Transaction *tran = tran_new();
3249 ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
3250 if (ret < 0) {
3251 goto out;
3254 ret = bdrv_refresh_perms(bs, errp);
3255 out:
3256 tran_finalize(tran, ret);
3258 return ret;
3262 * Opens the backing file for a BlockDriverState if not yet open
3264 * bdref_key specifies the key for the image's BlockdevRef in the options QDict.
3265 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3266 * itself, all options starting with "${bdref_key}." are considered part of the
3267 * BlockdevRef.
3269 * TODO Can this be unified with bdrv_open_image()?
3271 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
3272 const char *bdref_key, Error **errp)
3274 char *backing_filename = NULL;
3275 char *bdref_key_dot;
3276 const char *reference = NULL;
3277 int ret = 0;
3278 bool implicit_backing = false;
3279 BlockDriverState *backing_hd;
3280 QDict *options;
3281 QDict *tmp_parent_options = NULL;
3282 Error *local_err = NULL;
3284 if (bs->backing != NULL) {
3285 goto free_exit;
3288 /* NULL means an empty set of options */
3289 if (parent_options == NULL) {
3290 tmp_parent_options = qdict_new();
3291 parent_options = tmp_parent_options;
3294 bs->open_flags &= ~BDRV_O_NO_BACKING;
3296 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3297 qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
3298 g_free(bdref_key_dot);
3301 * Caution: while qdict_get_try_str() is fine, getting non-string
3302 * types would require more care. When @parent_options come from
3303 * -blockdev or blockdev_add, its members are typed according to
3304 * the QAPI schema, but when they come from -drive, they're all
3305 * QString.
3307 reference = qdict_get_try_str(parent_options, bdref_key);
3308 if (reference || qdict_haskey(options, "file.filename")) {
3309 /* keep backing_filename NULL */
3310 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
3311 qobject_unref(options);
3312 goto free_exit;
3313 } else {
3314 if (qdict_size(options) == 0) {
3315 /* If the user specifies options that do not modify the
3316 * backing file's behavior, we might still consider it the
3317 * implicit backing file. But it's easier this way, and
3318 * just specifying some of the backing BDS's options is
3319 * only possible with -drive anyway (otherwise the QAPI
3320 * schema forces the user to specify everything). */
3321 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
3324 backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
3325 if (local_err) {
3326 ret = -EINVAL;
3327 error_propagate(errp, local_err);
3328 qobject_unref(options);
3329 goto free_exit;
3333 if (!bs->drv || !bs->drv->supports_backing) {
3334 ret = -EINVAL;
3335 error_setg(errp, "Driver doesn't support backing files");
3336 qobject_unref(options);
3337 goto free_exit;
3340 if (!reference &&
3341 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
3342 qdict_put_str(options, "driver", bs->backing_format);
3345 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
3346 &child_of_bds, bdrv_backing_role(bs), errp);
3347 if (!backing_hd) {
3348 bs->open_flags |= BDRV_O_NO_BACKING;
3349 error_prepend(errp, "Could not open backing file: ");
3350 ret = -EINVAL;
3351 goto free_exit;
3354 if (implicit_backing) {
3355 bdrv_refresh_filename(backing_hd);
3356 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
3357 backing_hd->filename);
3360 /* Hook up the backing file link; drop our reference, bs owns the
3361 * backing_hd reference now */
3362 ret = bdrv_set_backing_hd(bs, backing_hd, errp);
3363 bdrv_unref(backing_hd);
3364 if (ret < 0) {
3365 goto free_exit;
3368 qdict_del(parent_options, bdref_key);
3370 free_exit:
3371 g_free(backing_filename);
3372 qobject_unref(tmp_parent_options);
3373 return ret;
3376 static BlockDriverState *
3377 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
3378 BlockDriverState *parent, const BdrvChildClass *child_class,
3379 BdrvChildRole child_role, bool allow_none, Error **errp)
3381 BlockDriverState *bs = NULL;
3382 QDict *image_options;
3383 char *bdref_key_dot;
3384 const char *reference;
3386 assert(child_class != NULL);
3388 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3389 qdict_extract_subqdict(options, &image_options, bdref_key_dot);
3390 g_free(bdref_key_dot);
3393 * Caution: while qdict_get_try_str() is fine, getting non-string
3394 * types would require more care. When @options come from
3395 * -blockdev or blockdev_add, its members are typed according to
3396 * the QAPI schema, but when they come from -drive, they're all
3397 * QString.
3399 reference = qdict_get_try_str(options, bdref_key);
3400 if (!filename && !reference && !qdict_size(image_options)) {
3401 if (!allow_none) {
3402 error_setg(errp, "A block device must be specified for \"%s\"",
3403 bdref_key);
3405 qobject_unref(image_options);
3406 goto done;
3409 bs = bdrv_open_inherit(filename, reference, image_options, 0,
3410 parent, child_class, child_role, errp);
3411 if (!bs) {
3412 goto done;
3415 done:
3416 qdict_del(options, bdref_key);
3417 return bs;
3421 * Opens a disk image whose options are given as BlockdevRef in another block
3422 * device's options.
3424 * If allow_none is true, no image will be opened if filename is false and no
3425 * BlockdevRef is given. NULL will be returned, but errp remains unset.
3427 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
3428 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3429 * itself, all options starting with "${bdref_key}." are considered part of the
3430 * BlockdevRef.
3432 * The BlockdevRef will be removed from the options QDict.
3434 BdrvChild *bdrv_open_child(const char *filename,
3435 QDict *options, const char *bdref_key,
3436 BlockDriverState *parent,
3437 const BdrvChildClass *child_class,
3438 BdrvChildRole child_role,
3439 bool allow_none, Error **errp)
3441 BlockDriverState *bs;
3443 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
3444 child_role, allow_none, errp);
3445 if (bs == NULL) {
3446 return NULL;
3449 return bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
3450 errp);
3454 * TODO Future callers may need to specify parent/child_class in order for
3455 * option inheritance to work. Existing callers use it for the root node.
3457 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
3459 BlockDriverState *bs = NULL;
3460 QObject *obj = NULL;
3461 QDict *qdict = NULL;
3462 const char *reference = NULL;
3463 Visitor *v = NULL;
3465 if (ref->type == QTYPE_QSTRING) {
3466 reference = ref->u.reference;
3467 } else {
3468 BlockdevOptions *options = &ref->u.definition;
3469 assert(ref->type == QTYPE_QDICT);
3471 v = qobject_output_visitor_new(&obj);
3472 visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
3473 visit_complete(v, &obj);
3475 qdict = qobject_to(QDict, obj);
3476 qdict_flatten(qdict);
3478 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for
3479 * compatibility with other callers) rather than what we want as the
3480 * real defaults. Apply the defaults here instead. */
3481 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
3482 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
3483 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
3484 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
3488 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp);
3489 obj = NULL;
3490 qobject_unref(obj);
3491 visit_free(v);
3492 return bs;
3495 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
3496 int flags,
3497 QDict *snapshot_options,
3498 Error **errp)
3500 /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
3501 char *tmp_filename = g_malloc0(PATH_MAX + 1);
3502 int64_t total_size;
3503 QemuOpts *opts = NULL;
3504 BlockDriverState *bs_snapshot = NULL;
3505 int ret;
3507 /* if snapshot, we create a temporary backing file and open it
3508 instead of opening 'filename' directly */
3510 /* Get the required size from the image */
3511 total_size = bdrv_getlength(bs);
3512 if (total_size < 0) {
3513 error_setg_errno(errp, -total_size, "Could not get image size");
3514 goto out;
3517 /* Create the temporary image */
3518 ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);
3519 if (ret < 0) {
3520 error_setg_errno(errp, -ret, "Could not get temporary filename");
3521 goto out;
3524 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
3525 &error_abort);
3526 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
3527 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
3528 qemu_opts_del(opts);
3529 if (ret < 0) {
3530 error_prepend(errp, "Could not create temporary overlay '%s': ",
3531 tmp_filename);
3532 goto out;
3535 /* Prepare options QDict for the temporary file */
3536 qdict_put_str(snapshot_options, "file.driver", "file");
3537 qdict_put_str(snapshot_options, "file.filename", tmp_filename);
3538 qdict_put_str(snapshot_options, "driver", "qcow2");
3540 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
3541 snapshot_options = NULL;
3542 if (!bs_snapshot) {
3543 goto out;
3546 ret = bdrv_append(bs_snapshot, bs, errp);
3547 if (ret < 0) {
3548 bs_snapshot = NULL;
3549 goto out;
3552 out:
3553 qobject_unref(snapshot_options);
3554 g_free(tmp_filename);
3555 return bs_snapshot;
3559 * Opens a disk image (raw, qcow2, vmdk, ...)
3561 * options is a QDict of options to pass to the block drivers, or NULL for an
3562 * empty set of options. The reference to the QDict belongs to the block layer
3563 * after the call (even on failure), so if the caller intends to reuse the
3564 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
3566 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
3567 * If it is not NULL, the referenced BDS will be reused.
3569 * The reference parameter may be used to specify an existing block device which
3570 * should be opened. If specified, neither options nor a filename may be given,
3571 * nor can an existing BDS be reused (that is, *pbs has to be NULL).
3573 static BlockDriverState *bdrv_open_inherit(const char *filename,
3574 const char *reference,
3575 QDict *options, int flags,
3576 BlockDriverState *parent,
3577 const BdrvChildClass *child_class,
3578 BdrvChildRole child_role,
3579 Error **errp)
3581 int ret;
3582 BlockBackend *file = NULL;
3583 BlockDriverState *bs;
3584 BlockDriver *drv = NULL;
3585 BdrvChild *child;
3586 const char *drvname;
3587 const char *backing;
3588 Error *local_err = NULL;
3589 QDict *snapshot_options = NULL;
3590 int snapshot_flags = 0;
3592 assert(!child_class || !flags);
3593 assert(!child_class == !parent);
3595 if (reference) {
3596 bool options_non_empty = options ? qdict_size(options) : false;
3597 qobject_unref(options);
3599 if (filename || options_non_empty) {
3600 error_setg(errp, "Cannot reference an existing block device with "
3601 "additional options or a new filename");
3602 return NULL;
3605 bs = bdrv_lookup_bs(reference, reference, errp);
3606 if (!bs) {
3607 return NULL;
3610 bdrv_ref(bs);
3611 return bs;
3614 bs = bdrv_new();
3616 /* NULL means an empty set of options */
3617 if (options == NULL) {
3618 options = qdict_new();
3621 /* json: syntax counts as explicit options, as if in the QDict */
3622 parse_json_protocol(options, &filename, &local_err);
3623 if (local_err) {
3624 goto fail;
3627 bs->explicit_options = qdict_clone_shallow(options);
3629 if (child_class) {
3630 bool parent_is_format;
3632 if (parent->drv) {
3633 parent_is_format = parent->drv->is_format;
3634 } else {
3636 * parent->drv is not set yet because this node is opened for
3637 * (potential) format probing. That means that @parent is going
3638 * to be a format node.
3640 parent_is_format = true;
3643 bs->inherits_from = parent;
3644 child_class->inherit_options(child_role, parent_is_format,
3645 &flags, options,
3646 parent->open_flags, parent->options);
3649 ret = bdrv_fill_options(&options, filename, &flags, &local_err);
3650 if (ret < 0) {
3651 goto fail;
3655 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
3656 * Caution: getting a boolean member of @options requires care.
3657 * When @options come from -blockdev or blockdev_add, members are
3658 * typed according to the QAPI schema, but when they come from
3659 * -drive, they're all QString.
3661 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
3662 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
3663 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
3664 } else {
3665 flags &= ~BDRV_O_RDWR;
3668 if (flags & BDRV_O_SNAPSHOT) {
3669 snapshot_options = qdict_new();
3670 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options,
3671 flags, options);
3672 /* Let bdrv_backing_options() override "read-only" */
3673 qdict_del(options, BDRV_OPT_READ_ONLY);
3674 bdrv_inherited_options(BDRV_CHILD_COW, true,
3675 &flags, options, flags, options);
3678 bs->open_flags = flags;
3679 bs->options = options;
3680 options = qdict_clone_shallow(options);
3682 /* Find the right image format driver */
3683 /* See cautionary note on accessing @options above */
3684 drvname = qdict_get_try_str(options, "driver");
3685 if (drvname) {
3686 drv = bdrv_find_format(drvname);
3687 if (!drv) {
3688 error_setg(errp, "Unknown driver: '%s'", drvname);
3689 goto fail;
3693 assert(drvname || !(flags & BDRV_O_PROTOCOL));
3695 /* See cautionary note on accessing @options above */
3696 backing = qdict_get_try_str(options, "backing");
3697 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
3698 (backing && *backing == '\0'))
3700 if (backing) {
3701 warn_report("Use of \"backing\": \"\" is deprecated; "
3702 "use \"backing\": null instead");
3704 flags |= BDRV_O_NO_BACKING;
3705 qdict_del(bs->explicit_options, "backing");
3706 qdict_del(bs->options, "backing");
3707 qdict_del(options, "backing");
3710 /* Open image file without format layer. This BlockBackend is only used for
3711 * probing, the block drivers will do their own bdrv_open_child() for the
3712 * same BDS, which is why we put the node name back into options. */
3713 if ((flags & BDRV_O_PROTOCOL) == 0) {
3714 BlockDriverState *file_bs;
3716 file_bs = bdrv_open_child_bs(filename, options, "file", bs,
3717 &child_of_bds, BDRV_CHILD_IMAGE,
3718 true, &local_err);
3719 if (local_err) {
3720 goto fail;
3722 if (file_bs != NULL) {
3723 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only
3724 * looking at the header to guess the image format. This works even
3725 * in cases where a guest would not see a consistent state. */
3726 file = blk_new(bdrv_get_aio_context(file_bs), 0, BLK_PERM_ALL);
3727 blk_insert_bs(file, file_bs, &local_err);
3728 bdrv_unref(file_bs);
3729 if (local_err) {
3730 goto fail;
3733 qdict_put_str(options, "file", bdrv_get_node_name(file_bs));
3737 /* Image format probing */
3738 bs->probed = !drv;
3739 if (!drv && file) {
3740 ret = find_image_format(file, filename, &drv, &local_err);
3741 if (ret < 0) {
3742 goto fail;
3745 * This option update would logically belong in bdrv_fill_options(),
3746 * but we first need to open bs->file for the probing to work, while
3747 * opening bs->file already requires the (mostly) final set of options
3748 * so that cache mode etc. can be inherited.
3750 * Adding the driver later is somewhat ugly, but it's not an option
3751 * that would ever be inherited, so it's correct. We just need to make
3752 * sure to update both bs->options (which has the full effective
3753 * options for bs) and options (which has file.* already removed).
3755 qdict_put_str(bs->options, "driver", drv->format_name);
3756 qdict_put_str(options, "driver", drv->format_name);
3757 } else if (!drv) {
3758 error_setg(errp, "Must specify either driver or file");
3759 goto fail;
3762 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
3763 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
3764 /* file must be NULL if a protocol BDS is about to be created
3765 * (the inverse results in an error message from bdrv_open_common()) */
3766 assert(!(flags & BDRV_O_PROTOCOL) || !file);
3768 /* Open the image */
3769 ret = bdrv_open_common(bs, file, options, &local_err);
3770 if (ret < 0) {
3771 goto fail;
3774 if (file) {
3775 blk_unref(file);
3776 file = NULL;
3779 /* If there is a backing file, use it */
3780 if ((flags & BDRV_O_NO_BACKING) == 0) {
3781 ret = bdrv_open_backing_file(bs, options, "backing", &local_err);
3782 if (ret < 0) {
3783 goto close_and_fail;
3787 /* Remove all children options and references
3788 * from bs->options and bs->explicit_options */
3789 QLIST_FOREACH(child, &bs->children, next) {
3790 char *child_key_dot;
3791 child_key_dot = g_strdup_printf("%s.", child->name);
3792 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot);
3793 qdict_extract_subqdict(bs->options, NULL, child_key_dot);
3794 qdict_del(bs->explicit_options, child->name);
3795 qdict_del(bs->options, child->name);
3796 g_free(child_key_dot);
3799 /* Check if any unknown options were used */
3800 if (qdict_size(options) != 0) {
3801 const QDictEntry *entry = qdict_first(options);
3802 if (flags & BDRV_O_PROTOCOL) {
3803 error_setg(errp, "Block protocol '%s' doesn't support the option "
3804 "'%s'", drv->format_name, entry->key);
3805 } else {
3806 error_setg(errp,
3807 "Block format '%s' does not support the option '%s'",
3808 drv->format_name, entry->key);
3811 goto close_and_fail;
3814 bdrv_parent_cb_change_media(bs, true);
3816 qobject_unref(options);
3817 options = NULL;
3819 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
3820 * temporary snapshot afterwards. */
3821 if (snapshot_flags) {
3822 BlockDriverState *snapshot_bs;
3823 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags,
3824 snapshot_options, &local_err);
3825 snapshot_options = NULL;
3826 if (local_err) {
3827 goto close_and_fail;
3829 /* We are not going to return bs but the overlay on top of it
3830 * (snapshot_bs); thus, we have to drop the strong reference to bs
3831 * (which we obtained by calling bdrv_new()). bs will not be deleted,
3832 * though, because the overlay still has a reference to it. */
3833 bdrv_unref(bs);
3834 bs = snapshot_bs;
3837 return bs;
3839 fail:
3840 blk_unref(file);
3841 qobject_unref(snapshot_options);
3842 qobject_unref(bs->explicit_options);
3843 qobject_unref(bs->options);
3844 qobject_unref(options);
3845 bs->options = NULL;
3846 bs->explicit_options = NULL;
3847 bdrv_unref(bs);
3848 error_propagate(errp, local_err);
3849 return NULL;
3851 close_and_fail:
3852 bdrv_unref(bs);
3853 qobject_unref(snapshot_options);
3854 qobject_unref(options);
3855 error_propagate(errp, local_err);
3856 return NULL;
3859 BlockDriverState *bdrv_open(const char *filename, const char *reference,
3860 QDict *options, int flags, Error **errp)
3862 return bdrv_open_inherit(filename, reference, options, flags, NULL,
3863 NULL, 0, errp);
3866 /* Return true if the NULL-terminated @list contains @str */
3867 static bool is_str_in_list(const char *str, const char *const *list)
3869 if (str && list) {
3870 int i;
3871 for (i = 0; list[i] != NULL; i++) {
3872 if (!strcmp(str, list[i])) {
3873 return true;
3877 return false;
3881 * Check that every option set in @bs->options is also set in
3882 * @new_opts.
3884 * Options listed in the common_options list and in
3885 * @bs->drv->mutable_opts are skipped.
3887 * Return 0 on success, otherwise return -EINVAL and set @errp.
3889 static int bdrv_reset_options_allowed(BlockDriverState *bs,
3890 const QDict *new_opts, Error **errp)
3892 const QDictEntry *e;
3893 /* These options are common to all block drivers and are handled
3894 * in bdrv_reopen_prepare() so they can be left out of @new_opts */
3895 const char *const common_options[] = {
3896 "node-name", "discard", "cache.direct", "cache.no-flush",
3897 "read-only", "auto-read-only", "detect-zeroes", NULL
3900 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) {
3901 if (!qdict_haskey(new_opts, e->key) &&
3902 !is_str_in_list(e->key, common_options) &&
3903 !is_str_in_list(e->key, bs->drv->mutable_opts)) {
3904 error_setg(errp, "Option '%s' cannot be reset "
3905 "to its default value", e->key);
3906 return -EINVAL;
3910 return 0;
3914 * Returns true if @child can be reached recursively from @bs
3916 static bool bdrv_recurse_has_child(BlockDriverState *bs,
3917 BlockDriverState *child)
3919 BdrvChild *c;
3921 if (bs == child) {
3922 return true;
3925 QLIST_FOREACH(c, &bs->children, next) {
3926 if (bdrv_recurse_has_child(c->bs, child)) {
3927 return true;
3931 return false;
3935 * Adds a BlockDriverState to a simple queue for an atomic, transactional
3936 * reopen of multiple devices.
3938 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT
3939 * already performed, or alternatively may be NULL a new BlockReopenQueue will
3940 * be created and initialized. This newly created BlockReopenQueue should be
3941 * passed back in for subsequent calls that are intended to be of the same
3942 * atomic 'set'.
3944 * bs is the BlockDriverState to add to the reopen queue.
3946 * options contains the changed options for the associated bs
3947 * (the BlockReopenQueue takes ownership)
3949 * flags contains the open flags for the associated bs
3951 * returns a pointer to bs_queue, which is either the newly allocated
3952 * bs_queue, or the existing bs_queue being used.
3954 * bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple().
3956 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
3957 BlockDriverState *bs,
3958 QDict *options,
3959 const BdrvChildClass *klass,
3960 BdrvChildRole role,
3961 bool parent_is_format,
3962 QDict *parent_options,
3963 int parent_flags,
3964 bool keep_old_opts)
3966 assert(bs != NULL);
3968 BlockReopenQueueEntry *bs_entry;
3969 BdrvChild *child;
3970 QDict *old_options, *explicit_options, *options_copy;
3971 int flags;
3972 QemuOpts *opts;
3974 /* Make sure that the caller remembered to use a drained section. This is
3975 * important to avoid graph changes between the recursive queuing here and
3976 * bdrv_reopen_multiple(). */
3977 assert(bs->quiesce_counter > 0);
3979 if (bs_queue == NULL) {
3980 bs_queue = g_new0(BlockReopenQueue, 1);
3981 QTAILQ_INIT(bs_queue);
3984 if (!options) {
3985 options = qdict_new();
3988 /* Check if this BlockDriverState is already in the queue */
3989 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
3990 if (bs == bs_entry->state.bs) {
3991 break;
3996 * Precedence of options:
3997 * 1. Explicitly passed in options (highest)
3998 * 2. Retained from explicitly set options of bs
3999 * 3. Inherited from parent node
4000 * 4. Retained from effective options of bs
4003 /* Old explicitly set values (don't overwrite by inherited value) */
4004 if (bs_entry || keep_old_opts) {
4005 old_options = qdict_clone_shallow(bs_entry ?
4006 bs_entry->state.explicit_options :
4007 bs->explicit_options);
4008 bdrv_join_options(bs, options, old_options);
4009 qobject_unref(old_options);
4012 explicit_options = qdict_clone_shallow(options);
4014 /* Inherit from parent node */
4015 if (parent_options) {
4016 flags = 0;
4017 klass->inherit_options(role, parent_is_format, &flags, options,
4018 parent_flags, parent_options);
4019 } else {
4020 flags = bdrv_get_flags(bs);
4023 if (keep_old_opts) {
4024 /* Old values are used for options that aren't set yet */
4025 old_options = qdict_clone_shallow(bs->options);
4026 bdrv_join_options(bs, options, old_options);
4027 qobject_unref(old_options);
4030 /* We have the final set of options so let's update the flags */
4031 options_copy = qdict_clone_shallow(options);
4032 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4033 qemu_opts_absorb_qdict(opts, options_copy, NULL);
4034 update_flags_from_options(&flags, opts);
4035 qemu_opts_del(opts);
4036 qobject_unref(options_copy);
4038 /* bdrv_open_inherit() sets and clears some additional flags internally */
4039 flags &= ~BDRV_O_PROTOCOL;
4040 if (flags & BDRV_O_RDWR) {
4041 flags |= BDRV_O_ALLOW_RDWR;
4044 if (!bs_entry) {
4045 bs_entry = g_new0(BlockReopenQueueEntry, 1);
4046 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry);
4047 } else {
4048 qobject_unref(bs_entry->state.options);
4049 qobject_unref(bs_entry->state.explicit_options);
4052 bs_entry->state.bs = bs;
4053 bs_entry->state.options = options;
4054 bs_entry->state.explicit_options = explicit_options;
4055 bs_entry->state.flags = flags;
4058 * If keep_old_opts is false then it means that unspecified
4059 * options must be reset to their original value. We don't allow
4060 * resetting 'backing' but we need to know if the option is
4061 * missing in order to decide if we have to return an error.
4063 if (!keep_old_opts) {
4064 bs_entry->state.backing_missing =
4065 !qdict_haskey(options, "backing") &&
4066 !qdict_haskey(options, "backing.driver");
4069 QLIST_FOREACH(child, &bs->children, next) {
4070 QDict *new_child_options = NULL;
4071 bool child_keep_old = keep_old_opts;
4073 /* reopen can only change the options of block devices that were
4074 * implicitly created and inherited options. For other (referenced)
4075 * block devices, a syntax like "backing.foo" results in an error. */
4076 if (child->bs->inherits_from != bs) {
4077 continue;
4080 /* Check if the options contain a child reference */
4081 if (qdict_haskey(options, child->name)) {
4082 const char *childref = qdict_get_try_str(options, child->name);
4084 * The current child must not be reopened if the child
4085 * reference is null or points to a different node.
4087 if (g_strcmp0(childref, child->bs->node_name)) {
4088 continue;
4091 * If the child reference points to the current child then
4092 * reopen it with its existing set of options (note that
4093 * it can still inherit new options from the parent).
4095 child_keep_old = true;
4096 } else {
4097 /* Extract child options ("child-name.*") */
4098 char *child_key_dot = g_strdup_printf("%s.", child->name);
4099 qdict_extract_subqdict(explicit_options, NULL, child_key_dot);
4100 qdict_extract_subqdict(options, &new_child_options, child_key_dot);
4101 g_free(child_key_dot);
4104 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
4105 child->klass, child->role, bs->drv->is_format,
4106 options, flags, child_keep_old);
4109 return bs_queue;
4112 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
4113 BlockDriverState *bs,
4114 QDict *options, bool keep_old_opts)
4116 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false,
4117 NULL, 0, keep_old_opts);
4120 void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue)
4122 if (bs_queue) {
4123 BlockReopenQueueEntry *bs_entry, *next;
4124 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
4125 qobject_unref(bs_entry->state.explicit_options);
4126 qobject_unref(bs_entry->state.options);
4127 g_free(bs_entry);
4129 g_free(bs_queue);
4134 * Reopen multiple BlockDriverStates atomically & transactionally.
4136 * The queue passed in (bs_queue) must have been built up previous
4137 * via bdrv_reopen_queue().
4139 * Reopens all BDS specified in the queue, with the appropriate
4140 * flags. All devices are prepared for reopen, and failure of any
4141 * device will cause all device changes to be abandoned, and intermediate
4142 * data cleaned up.
4144 * If all devices prepare successfully, then the changes are committed
4145 * to all devices.
4147 * All affected nodes must be drained between bdrv_reopen_queue() and
4148 * bdrv_reopen_multiple().
4150 * To be called from the main thread, with all other AioContexts unlocked.
4152 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
4154 int ret = -1;
4155 BlockReopenQueueEntry *bs_entry, *next;
4156 AioContext *ctx;
4157 Transaction *tran = tran_new();
4158 g_autoptr(GHashTable) found = NULL;
4159 g_autoptr(GSList) refresh_list = NULL;
4161 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
4162 assert(bs_queue != NULL);
4164 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4165 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4166 aio_context_acquire(ctx);
4167 ret = bdrv_flush(bs_entry->state.bs);
4168 aio_context_release(ctx);
4169 if (ret < 0) {
4170 error_setg_errno(errp, -ret, "Error flushing drive");
4171 goto abort;
4175 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4176 assert(bs_entry->state.bs->quiesce_counter > 0);
4177 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4178 aio_context_acquire(ctx);
4179 ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp);
4180 aio_context_release(ctx);
4181 if (ret < 0) {
4182 goto abort;
4184 bs_entry->prepared = true;
4187 found = g_hash_table_new(NULL, NULL);
4188 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4189 BDRVReopenState *state = &bs_entry->state;
4191 refresh_list = bdrv_topological_dfs(refresh_list, found, state->bs);
4192 if (state->old_backing_bs) {
4193 refresh_list = bdrv_topological_dfs(refresh_list, found,
4194 state->old_backing_bs);
4196 if (state->old_file_bs) {
4197 refresh_list = bdrv_topological_dfs(refresh_list, found,
4198 state->old_file_bs);
4203 * Note that file-posix driver rely on permission update done during reopen
4204 * (even if no permission changed), because it wants "new" permissions for
4205 * reconfiguring the fd and that's why it does it in raw_check_perm(), not
4206 * in raw_reopen_prepare() which is called with "old" permissions.
4208 ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp);
4209 if (ret < 0) {
4210 goto abort;
4214 * If we reach this point, we have success and just need to apply the
4215 * changes.
4217 * Reverse order is used to comfort qcow2 driver: on commit it need to write
4218 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But
4219 * children are usually goes after parents in reopen-queue, so go from last
4220 * to first element.
4222 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
4223 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4224 aio_context_acquire(ctx);
4225 bdrv_reopen_commit(&bs_entry->state);
4226 aio_context_release(ctx);
4229 tran_commit(tran);
4231 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
4232 BlockDriverState *bs = bs_entry->state.bs;
4234 if (bs->drv->bdrv_reopen_commit_post) {
4235 ctx = bdrv_get_aio_context(bs);
4236 aio_context_acquire(ctx);
4237 bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
4238 aio_context_release(ctx);
4242 ret = 0;
4243 goto cleanup;
4245 abort:
4246 tran_abort(tran);
4247 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
4248 if (bs_entry->prepared) {
4249 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4250 aio_context_acquire(ctx);
4251 bdrv_reopen_abort(&bs_entry->state);
4252 aio_context_release(ctx);
4256 cleanup:
4257 bdrv_reopen_queue_free(bs_queue);
4259 return ret;
4262 int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
4263 Error **errp)
4265 AioContext *ctx = bdrv_get_aio_context(bs);
4266 BlockReopenQueue *queue;
4267 int ret;
4269 bdrv_subtree_drained_begin(bs);
4270 if (ctx != qemu_get_aio_context()) {
4271 aio_context_release(ctx);
4274 queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
4275 ret = bdrv_reopen_multiple(queue, errp);
4277 if (ctx != qemu_get_aio_context()) {
4278 aio_context_acquire(ctx);
4280 bdrv_subtree_drained_end(bs);
4282 return ret;
4285 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
4286 Error **errp)
4288 QDict *opts = qdict_new();
4290 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
4292 return bdrv_reopen(bs, opts, true, errp);
4296 * Take a BDRVReopenState and check if the value of 'backing' in the
4297 * reopen_state->options QDict is valid or not.
4299 * If 'backing' is missing from the QDict then return 0.
4301 * If 'backing' contains the node name of the backing file of
4302 * reopen_state->bs then return 0.
4304 * If 'backing' contains a different node name (or is null) then check
4305 * whether the current backing file can be replaced with the new one.
4306 * If that's the case then reopen_state->replace_backing_bs is set to
4307 * true and reopen_state->new_backing_bs contains a pointer to the new
4308 * backing BlockDriverState (or NULL).
4310 * Return 0 on success, otherwise return < 0 and set @errp.
4312 static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
4313 bool is_backing, Transaction *tran,
4314 Error **errp)
4316 BlockDriverState *bs = reopen_state->bs;
4317 BlockDriverState *new_child_bs;
4318 BlockDriverState *old_child_bs = is_backing ? child_bs(bs->backing) :
4319 child_bs(bs->file);
4320 const char *child_name = is_backing ? "backing" : "file";
4321 QObject *value;
4322 const char *str;
4324 value = qdict_get(reopen_state->options, child_name);
4325 if (value == NULL) {
4326 return 0;
4329 switch (qobject_type(value)) {
4330 case QTYPE_QNULL:
4331 assert(is_backing); /* The 'file' option does not allow a null value */
4332 new_child_bs = NULL;
4333 break;
4334 case QTYPE_QSTRING:
4335 str = qstring_get_str(qobject_to(QString, value));
4336 new_child_bs = bdrv_lookup_bs(NULL, str, errp);
4337 if (new_child_bs == NULL) {
4338 return -EINVAL;
4339 } else if (bdrv_recurse_has_child(new_child_bs, bs)) {
4340 error_setg(errp, "Making '%s' a %s child of '%s' would create a "
4341 "cycle", str, child_name, bs->node_name);
4342 return -EINVAL;
4344 break;
4345 default:
4347 * The options QDict has been flattened, so 'backing' and 'file'
4348 * do not allow any other data type here.
4350 g_assert_not_reached();
4353 if (old_child_bs == new_child_bs) {
4354 return 0;
4357 if (old_child_bs) {
4358 if (bdrv_skip_implicit_filters(old_child_bs) == new_child_bs) {
4359 return 0;
4362 if (old_child_bs->implicit) {
4363 error_setg(errp, "Cannot replace implicit %s child of %s",
4364 child_name, bs->node_name);
4365 return -EPERM;
4369 if (bs->drv->is_filter && !old_child_bs) {
4371 * Filters always have a file or a backing child, so we are trying to
4372 * change wrong child
4374 error_setg(errp, "'%s' is a %s filter node that does not support a "
4375 "%s child", bs->node_name, bs->drv->format_name, child_name);
4376 return -EINVAL;
4379 if (is_backing) {
4380 reopen_state->old_backing_bs = old_child_bs;
4381 } else {
4382 reopen_state->old_file_bs = old_child_bs;
4385 return bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing,
4386 tran, errp);
4390 * Prepares a BlockDriverState for reopen. All changes are staged in the
4391 * 'opaque' field of the BDRVReopenState, which is used and allocated by
4392 * the block driver layer .bdrv_reopen_prepare()
4394 * bs is the BlockDriverState to reopen
4395 * flags are the new open flags
4396 * queue is the reopen queue
4398 * Returns 0 on success, non-zero on error. On error errp will be set
4399 * as well.
4401 * On failure, bdrv_reopen_abort() will be called to clean up any data.
4402 * It is the responsibility of the caller to then call the abort() or
4403 * commit() for any other BDS that have been left in a prepare() state
4406 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
4407 BlockReopenQueue *queue,
4408 Transaction *change_child_tran, Error **errp)
4410 int ret = -1;
4411 int old_flags;
4412 Error *local_err = NULL;
4413 BlockDriver *drv;
4414 QemuOpts *opts;
4415 QDict *orig_reopen_opts;
4416 char *discard = NULL;
4417 bool read_only;
4418 bool drv_prepared = false;
4420 assert(reopen_state != NULL);
4421 assert(reopen_state->bs->drv != NULL);
4422 drv = reopen_state->bs->drv;
4424 /* This function and each driver's bdrv_reopen_prepare() remove
4425 * entries from reopen_state->options as they are processed, so
4426 * we need to make a copy of the original QDict. */
4427 orig_reopen_opts = qdict_clone_shallow(reopen_state->options);
4429 /* Process generic block layer options */
4430 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4431 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) {
4432 ret = -EINVAL;
4433 goto error;
4436 /* This was already called in bdrv_reopen_queue_child() so the flags
4437 * are up-to-date. This time we simply want to remove the options from
4438 * QemuOpts in order to indicate that they have been processed. */
4439 old_flags = reopen_state->flags;
4440 update_flags_from_options(&reopen_state->flags, opts);
4441 assert(old_flags == reopen_state->flags);
4443 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD);
4444 if (discard != NULL) {
4445 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) {
4446 error_setg(errp, "Invalid discard option");
4447 ret = -EINVAL;
4448 goto error;
4452 reopen_state->detect_zeroes =
4453 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err);
4454 if (local_err) {
4455 error_propagate(errp, local_err);
4456 ret = -EINVAL;
4457 goto error;
4460 /* All other options (including node-name and driver) must be unchanged.
4461 * Put them back into the QDict, so that they are checked at the end
4462 * of this function. */
4463 qemu_opts_to_qdict(opts, reopen_state->options);
4465 /* If we are to stay read-only, do not allow permission change
4466 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
4467 * not set, or if the BDS still has copy_on_read enabled */
4468 read_only = !(reopen_state->flags & BDRV_O_RDWR);
4469 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
4470 if (local_err) {
4471 error_propagate(errp, local_err);
4472 goto error;
4475 if (drv->bdrv_reopen_prepare) {
4477 * If a driver-specific option is missing, it means that we
4478 * should reset it to its default value.
4479 * But not all options allow that, so we need to check it first.
4481 ret = bdrv_reset_options_allowed(reopen_state->bs,
4482 reopen_state->options, errp);
4483 if (ret) {
4484 goto error;
4487 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
4488 if (ret) {
4489 if (local_err != NULL) {
4490 error_propagate(errp, local_err);
4491 } else {
4492 bdrv_refresh_filename(reopen_state->bs);
4493 error_setg(errp, "failed while preparing to reopen image '%s'",
4494 reopen_state->bs->filename);
4496 goto error;
4498 } else {
4499 /* It is currently mandatory to have a bdrv_reopen_prepare()
4500 * handler for each supported drv. */
4501 error_setg(errp, "Block format '%s' used by node '%s' "
4502 "does not support reopening files", drv->format_name,
4503 bdrv_get_device_or_node_name(reopen_state->bs));
4504 ret = -1;
4505 goto error;
4508 drv_prepared = true;
4511 * We must provide the 'backing' option if the BDS has a backing
4512 * file or if the image file has a backing file name as part of
4513 * its metadata. Otherwise the 'backing' option can be omitted.
4515 if (drv->supports_backing && reopen_state->backing_missing &&
4516 (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) {
4517 error_setg(errp, "backing is missing for '%s'",
4518 reopen_state->bs->node_name);
4519 ret = -EINVAL;
4520 goto error;
4524 * Allow changing the 'backing' option. The new value can be
4525 * either a reference to an existing node (using its node name)
4526 * or NULL to simply detach the current backing file.
4528 ret = bdrv_reopen_parse_file_or_backing(reopen_state, true,
4529 change_child_tran, errp);
4530 if (ret < 0) {
4531 goto error;
4533 qdict_del(reopen_state->options, "backing");
4535 /* Allow changing the 'file' option. In this case NULL is not allowed */
4536 ret = bdrv_reopen_parse_file_or_backing(reopen_state, false,
4537 change_child_tran, errp);
4538 if (ret < 0) {
4539 goto error;
4541 qdict_del(reopen_state->options, "file");
4543 /* Options that are not handled are only okay if they are unchanged
4544 * compared to the old state. It is expected that some options are only
4545 * used for the initial open, but not reopen (e.g. filename) */
4546 if (qdict_size(reopen_state->options)) {
4547 const QDictEntry *entry = qdict_first(reopen_state->options);
4549 do {
4550 QObject *new = entry->value;
4551 QObject *old = qdict_get(reopen_state->bs->options, entry->key);
4553 /* Allow child references (child_name=node_name) as long as they
4554 * point to the current child (i.e. everything stays the same). */
4555 if (qobject_type(new) == QTYPE_QSTRING) {
4556 BdrvChild *child;
4557 QLIST_FOREACH(child, &reopen_state->bs->children, next) {
4558 if (!strcmp(child->name, entry->key)) {
4559 break;
4563 if (child) {
4564 if (!strcmp(child->bs->node_name,
4565 qstring_get_str(qobject_to(QString, new)))) {
4566 continue; /* Found child with this name, skip option */
4572 * TODO: When using -drive to specify blockdev options, all values
4573 * will be strings; however, when using -blockdev, blockdev-add or
4574 * filenames using the json:{} pseudo-protocol, they will be
4575 * correctly typed.
4576 * In contrast, reopening options are (currently) always strings
4577 * (because you can only specify them through qemu-io; all other
4578 * callers do not specify any options).
4579 * Therefore, when using anything other than -drive to create a BDS,
4580 * this cannot detect non-string options as unchanged, because
4581 * qobject_is_equal() always returns false for objects of different
4582 * type. In the future, this should be remedied by correctly typing
4583 * all options. For now, this is not too big of an issue because
4584 * the user can simply omit options which cannot be changed anyway,
4585 * so they will stay unchanged.
4587 if (!qobject_is_equal(new, old)) {
4588 error_setg(errp, "Cannot change the option '%s'", entry->key);
4589 ret = -EINVAL;
4590 goto error;
4592 } while ((entry = qdict_next(reopen_state->options, entry)));
4595 ret = 0;
4597 /* Restore the original reopen_state->options QDict */
4598 qobject_unref(reopen_state->options);
4599 reopen_state->options = qobject_ref(orig_reopen_opts);
4601 error:
4602 if (ret < 0 && drv_prepared) {
4603 /* drv->bdrv_reopen_prepare() has succeeded, so we need to
4604 * call drv->bdrv_reopen_abort() before signaling an error
4605 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort()
4606 * when the respective bdrv_reopen_prepare() has failed) */
4607 if (drv->bdrv_reopen_abort) {
4608 drv->bdrv_reopen_abort(reopen_state);
4611 qemu_opts_del(opts);
4612 qobject_unref(orig_reopen_opts);
4613 g_free(discard);
4614 return ret;
4618 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and
4619 * makes them final by swapping the staging BlockDriverState contents into
4620 * the active BlockDriverState contents.
4622 static void bdrv_reopen_commit(BDRVReopenState *reopen_state)
4624 BlockDriver *drv;
4625 BlockDriverState *bs;
4626 BdrvChild *child;
4628 assert(reopen_state != NULL);
4629 bs = reopen_state->bs;
4630 drv = bs->drv;
4631 assert(drv != NULL);
4633 /* If there are any driver level actions to take */
4634 if (drv->bdrv_reopen_commit) {
4635 drv->bdrv_reopen_commit(reopen_state);
4638 /* set BDS specific flags now */
4639 qobject_unref(bs->explicit_options);
4640 qobject_unref(bs->options);
4641 qobject_ref(reopen_state->explicit_options);
4642 qobject_ref(reopen_state->options);
4644 bs->explicit_options = reopen_state->explicit_options;
4645 bs->options = reopen_state->options;
4646 bs->open_flags = reopen_state->flags;
4647 bs->detect_zeroes = reopen_state->detect_zeroes;
4649 /* Remove child references from bs->options and bs->explicit_options.
4650 * Child options were already removed in bdrv_reopen_queue_child() */
4651 QLIST_FOREACH(child, &bs->children, next) {
4652 qdict_del(bs->explicit_options, child->name);
4653 qdict_del(bs->options, child->name);
4655 /* backing is probably removed, so it's not handled by previous loop */
4656 qdict_del(bs->explicit_options, "backing");
4657 qdict_del(bs->options, "backing");
4659 bdrv_refresh_limits(bs, NULL, NULL);
4663 * Abort the reopen, and delete and free the staged changes in
4664 * reopen_state
4666 static void bdrv_reopen_abort(BDRVReopenState *reopen_state)
4668 BlockDriver *drv;
4670 assert(reopen_state != NULL);
4671 drv = reopen_state->bs->drv;
4672 assert(drv != NULL);
4674 if (drv->bdrv_reopen_abort) {
4675 drv->bdrv_reopen_abort(reopen_state);
4680 static void bdrv_close(BlockDriverState *bs)
4682 BdrvAioNotifier *ban, *ban_next;
4683 BdrvChild *child, *next;
4685 assert(!bs->refcnt);
4687 bdrv_drained_begin(bs); /* complete I/O */
4688 bdrv_flush(bs);
4689 bdrv_drain(bs); /* in case flush left pending I/O */
4691 if (bs->drv) {
4692 if (bs->drv->bdrv_close) {
4693 /* Must unfreeze all children, so bdrv_unref_child() works */
4694 bs->drv->bdrv_close(bs);
4696 bs->drv = NULL;
4699 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
4700 bdrv_unref_child(bs, child);
4703 bs->backing = NULL;
4704 bs->file = NULL;
4705 g_free(bs->opaque);
4706 bs->opaque = NULL;
4707 qatomic_set(&bs->copy_on_read, 0);
4708 bs->backing_file[0] = '\0';
4709 bs->backing_format[0] = '\0';
4710 bs->total_sectors = 0;
4711 bs->encrypted = false;
4712 bs->sg = false;
4713 qobject_unref(bs->options);
4714 qobject_unref(bs->explicit_options);
4715 bs->options = NULL;
4716 bs->explicit_options = NULL;
4717 qobject_unref(bs->full_open_options);
4718 bs->full_open_options = NULL;
4719 g_free(bs->block_status_cache);
4720 bs->block_status_cache = NULL;
4722 bdrv_release_named_dirty_bitmaps(bs);
4723 assert(QLIST_EMPTY(&bs->dirty_bitmaps));
4725 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
4726 g_free(ban);
4728 QLIST_INIT(&bs->aio_notifiers);
4729 bdrv_drained_end(bs);
4732 * If we're still inside some bdrv_drain_all_begin()/end() sections, end
4733 * them now since this BDS won't exist anymore when bdrv_drain_all_end()
4734 * gets called.
4736 if (bs->quiesce_counter) {
4737 bdrv_drain_all_end_quiesce(bs);
4741 void bdrv_close_all(void)
4743 assert(job_next(NULL) == NULL);
4745 /* Drop references from requests still in flight, such as canceled block
4746 * jobs whose AIO context has not been polled yet */
4747 bdrv_drain_all();
4749 blk_remove_all_bs();
4750 blockdev_close_all_bdrv_states();
4752 assert(QTAILQ_EMPTY(&all_bdrv_states));
4755 static bool should_update_child(BdrvChild *c, BlockDriverState *to)
4757 GQueue *queue;
4758 GHashTable *found;
4759 bool ret;
4761 if (c->klass->stay_at_node) {
4762 return false;
4765 /* If the child @c belongs to the BDS @to, replacing the current
4766 * c->bs by @to would mean to create a loop.
4768 * Such a case occurs when appending a BDS to a backing chain.
4769 * For instance, imagine the following chain:
4771 * guest device -> node A -> further backing chain...
4773 * Now we create a new BDS B which we want to put on top of this
4774 * chain, so we first attach A as its backing node:
4776 * node B
4779 * guest device -> node A -> further backing chain...
4781 * Finally we want to replace A by B. When doing that, we want to
4782 * replace all pointers to A by pointers to B -- except for the
4783 * pointer from B because (1) that would create a loop, and (2)
4784 * that pointer should simply stay intact:
4786 * guest device -> node B
4789 * node A -> further backing chain...
4791 * In general, when replacing a node A (c->bs) by a node B (@to),
4792 * if A is a child of B, that means we cannot replace A by B there
4793 * because that would create a loop. Silently detaching A from B
4794 * is also not really an option. So overall just leaving A in
4795 * place there is the most sensible choice.
4797 * We would also create a loop in any cases where @c is only
4798 * indirectly referenced by @to. Prevent this by returning false
4799 * if @c is found (by breadth-first search) anywhere in the whole
4800 * subtree of @to.
4803 ret = true;
4804 found = g_hash_table_new(NULL, NULL);
4805 g_hash_table_add(found, to);
4806 queue = g_queue_new();
4807 g_queue_push_tail(queue, to);
4809 while (!g_queue_is_empty(queue)) {
4810 BlockDriverState *v = g_queue_pop_head(queue);
4811 BdrvChild *c2;
4813 QLIST_FOREACH(c2, &v->children, next) {
4814 if (c2 == c) {
4815 ret = false;
4816 break;
4819 if (g_hash_table_contains(found, c2->bs)) {
4820 continue;
4823 g_queue_push_tail(queue, c2->bs);
4824 g_hash_table_add(found, c2->bs);
4828 g_queue_free(queue);
4829 g_hash_table_destroy(found);
4831 return ret;
4834 typedef struct BdrvRemoveFilterOrCowChild {
4835 BdrvChild *child;
4836 bool is_backing;
4837 } BdrvRemoveFilterOrCowChild;
4839 static void bdrv_remove_filter_or_cow_child_abort(void *opaque)
4841 BdrvRemoveFilterOrCowChild *s = opaque;
4842 BlockDriverState *parent_bs = s->child->opaque;
4844 QLIST_INSERT_HEAD(&parent_bs->children, s->child, next);
4845 if (s->is_backing) {
4846 parent_bs->backing = s->child;
4847 } else {
4848 parent_bs->file = s->child;
4852 * We don't have to restore child->bs here to undo bdrv_replace_child_tran()
4853 * because that function is transactionable and it registered own completion
4854 * entries in @tran, so .abort() for bdrv_replace_child_safe() will be
4855 * called automatically.
4859 static void bdrv_remove_filter_or_cow_child_commit(void *opaque)
4861 BdrvRemoveFilterOrCowChild *s = opaque;
4863 bdrv_child_free(s->child);
4866 static TransactionActionDrv bdrv_remove_filter_or_cow_child_drv = {
4867 .abort = bdrv_remove_filter_or_cow_child_abort,
4868 .commit = bdrv_remove_filter_or_cow_child_commit,
4869 .clean = g_free,
4873 * A function to remove backing or file child of @bs.
4874 * Function doesn't update permissions, caller is responsible for this.
4876 static void bdrv_remove_file_or_backing_child(BlockDriverState *bs,
4877 BdrvChild *child,
4878 Transaction *tran)
4880 BdrvRemoveFilterOrCowChild *s;
4882 assert(child == bs->backing || child == bs->file);
4884 if (!child) {
4885 return;
4888 if (child->bs) {
4889 bdrv_replace_child_tran(child, NULL, tran);
4892 s = g_new(BdrvRemoveFilterOrCowChild, 1);
4893 *s = (BdrvRemoveFilterOrCowChild) {
4894 .child = child,
4895 .is_backing = (child == bs->backing),
4897 tran_add(tran, &bdrv_remove_filter_or_cow_child_drv, s);
4899 QLIST_SAFE_REMOVE(child, next);
4900 if (s->is_backing) {
4901 bs->backing = NULL;
4902 } else {
4903 bs->file = NULL;
4908 * A function to remove backing-chain child of @bs if exists: cow child for
4909 * format nodes (always .backing) and filter child for filters (may be .file or
4910 * .backing)
4912 static void bdrv_remove_filter_or_cow_child(BlockDriverState *bs,
4913 Transaction *tran)
4915 bdrv_remove_file_or_backing_child(bs, bdrv_filter_or_cow_child(bs), tran);
4918 static int bdrv_replace_node_noperm(BlockDriverState *from,
4919 BlockDriverState *to,
4920 bool auto_skip, Transaction *tran,
4921 Error **errp)
4923 BdrvChild *c, *next;
4925 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
4926 assert(c->bs == from);
4927 if (!should_update_child(c, to)) {
4928 if (auto_skip) {
4929 continue;
4931 error_setg(errp, "Should not change '%s' link to '%s'",
4932 c->name, from->node_name);
4933 return -EINVAL;
4935 if (c->frozen) {
4936 error_setg(errp, "Cannot change '%s' link to '%s'",
4937 c->name, from->node_name);
4938 return -EPERM;
4940 bdrv_replace_child_tran(c, to, tran);
4943 return 0;
4947 * With auto_skip=true bdrv_replace_node_common skips updating from parents
4948 * if it creates a parent-child relation loop or if parent is block-job.
4950 * With auto_skip=false the error is returned if from has a parent which should
4951 * not be updated.
4953 * With @detach_subchain=true @to must be in a backing chain of @from. In this
4954 * case backing link of the cow-parent of @to is removed.
4956 static int bdrv_replace_node_common(BlockDriverState *from,
4957 BlockDriverState *to,
4958 bool auto_skip, bool detach_subchain,
4959 Error **errp)
4961 Transaction *tran = tran_new();
4962 g_autoptr(GHashTable) found = NULL;
4963 g_autoptr(GSList) refresh_list = NULL;
4964 BlockDriverState *to_cow_parent = NULL;
4965 int ret;
4967 if (detach_subchain) {
4968 assert(bdrv_chain_contains(from, to));
4969 assert(from != to);
4970 for (to_cow_parent = from;
4971 bdrv_filter_or_cow_bs(to_cow_parent) != to;
4972 to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent))
4978 /* Make sure that @from doesn't go away until we have successfully attached
4979 * all of its parents to @to. */
4980 bdrv_ref(from);
4982 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
4983 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to));
4984 bdrv_drained_begin(from);
4987 * Do the replacement without permission update.
4988 * Replacement may influence the permissions, we should calculate new
4989 * permissions based on new graph. If we fail, we'll roll-back the
4990 * replacement.
4992 ret = bdrv_replace_node_noperm(from, to, auto_skip, tran, errp);
4993 if (ret < 0) {
4994 goto out;
4997 if (detach_subchain) {
4998 bdrv_remove_filter_or_cow_child(to_cow_parent, tran);
5001 found = g_hash_table_new(NULL, NULL);
5003 refresh_list = bdrv_topological_dfs(refresh_list, found, to);
5004 refresh_list = bdrv_topological_dfs(refresh_list, found, from);
5006 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
5007 if (ret < 0) {
5008 goto out;
5011 ret = 0;
5013 out:
5014 tran_finalize(tran, ret);
5016 bdrv_drained_end(from);
5017 bdrv_unref(from);
5019 return ret;
5022 int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
5023 Error **errp)
5025 return bdrv_replace_node_common(from, to, true, false, errp);
5028 int bdrv_drop_filter(BlockDriverState *bs, Error **errp)
5030 return bdrv_replace_node_common(bs, bdrv_filter_or_cow_bs(bs), true, true,
5031 errp);
5035 * Add new bs contents at the top of an image chain while the chain is
5036 * live, while keeping required fields on the top layer.
5038 * This will modify the BlockDriverState fields, and swap contents
5039 * between bs_new and bs_top. Both bs_new and bs_top are modified.
5041 * bs_new must not be attached to a BlockBackend and must not have backing
5042 * child.
5044 * This function does not create any image files.
5046 int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
5047 Error **errp)
5049 int ret;
5050 Transaction *tran = tran_new();
5052 assert(!bs_new->backing);
5054 ret = bdrv_attach_child_noperm(bs_new, bs_top, "backing",
5055 &child_of_bds, bdrv_backing_role(bs_new),
5056 &bs_new->backing, tran, errp);
5057 if (ret < 0) {
5058 goto out;
5061 ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp);
5062 if (ret < 0) {
5063 goto out;
5066 ret = bdrv_refresh_perms(bs_new, errp);
5067 out:
5068 tran_finalize(tran, ret);
5070 bdrv_refresh_limits(bs_top, NULL, NULL);
5072 return ret;
5075 /* Not for empty child */
5076 int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
5077 Error **errp)
5079 int ret;
5080 Transaction *tran = tran_new();
5081 g_autoptr(GHashTable) found = NULL;
5082 g_autoptr(GSList) refresh_list = NULL;
5083 BlockDriverState *old_bs = child->bs;
5085 bdrv_ref(old_bs);
5086 bdrv_drained_begin(old_bs);
5087 bdrv_drained_begin(new_bs);
5089 bdrv_replace_child_tran(child, new_bs, tran);
5091 found = g_hash_table_new(NULL, NULL);
5092 refresh_list = bdrv_topological_dfs(refresh_list, found, old_bs);
5093 refresh_list = bdrv_topological_dfs(refresh_list, found, new_bs);
5095 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
5097 tran_finalize(tran, ret);
5099 bdrv_drained_end(old_bs);
5100 bdrv_drained_end(new_bs);
5101 bdrv_unref(old_bs);
5103 return ret;
5106 static void bdrv_delete(BlockDriverState *bs)
5108 assert(bdrv_op_blocker_is_empty(bs));
5109 assert(!bs->refcnt);
5111 /* remove from list, if necessary */
5112 if (bs->node_name[0] != '\0') {
5113 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
5115 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
5117 bdrv_close(bs);
5119 g_free(bs);
5124 * Replace @bs by newly created block node.
5126 * @options is a QDict of options to pass to the block drivers, or NULL for an
5127 * empty set of options. The reference to the QDict belongs to the block layer
5128 * after the call (even on failure), so if the caller intends to reuse the
5129 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
5131 BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options,
5132 int flags, Error **errp)
5134 ERRP_GUARD();
5135 int ret;
5136 BlockDriverState *new_node_bs = NULL;
5137 const char *drvname, *node_name;
5138 BlockDriver *drv;
5140 drvname = qdict_get_try_str(options, "driver");
5141 if (!drvname) {
5142 error_setg(errp, "driver is not specified");
5143 goto fail;
5146 drv = bdrv_find_format(drvname);
5147 if (!drv) {
5148 error_setg(errp, "Unknown driver: '%s'", drvname);
5149 goto fail;
5152 node_name = qdict_get_try_str(options, "node-name");
5154 new_node_bs = bdrv_new_open_driver_opts(drv, node_name, options, flags,
5155 errp);
5156 options = NULL; /* bdrv_new_open_driver() eats options */
5157 if (!new_node_bs) {
5158 error_prepend(errp, "Could not create node: ");
5159 goto fail;
5162 bdrv_drained_begin(bs);
5163 ret = bdrv_replace_node(bs, new_node_bs, errp);
5164 bdrv_drained_end(bs);
5166 if (ret < 0) {
5167 error_prepend(errp, "Could not replace node: ");
5168 goto fail;
5171 return new_node_bs;
5173 fail:
5174 qobject_unref(options);
5175 bdrv_unref(new_node_bs);
5176 return NULL;
5180 * Run consistency checks on an image
5182 * Returns 0 if the check could be completed (it doesn't mean that the image is
5183 * free of errors) or -errno when an internal error occurred. The results of the
5184 * check are stored in res.
5186 int coroutine_fn bdrv_co_check(BlockDriverState *bs,
5187 BdrvCheckResult *res, BdrvCheckMode fix)
5189 if (bs->drv == NULL) {
5190 return -ENOMEDIUM;
5192 if (bs->drv->bdrv_co_check == NULL) {
5193 return -ENOTSUP;
5196 memset(res, 0, sizeof(*res));
5197 return bs->drv->bdrv_co_check(bs, res, fix);
5201 * Return values:
5202 * 0 - success
5203 * -EINVAL - backing format specified, but no file
5204 * -ENOSPC - can't update the backing file because no space is left in the
5205 * image file header
5206 * -ENOTSUP - format driver doesn't support changing the backing file
5208 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
5209 const char *backing_fmt, bool require)
5211 BlockDriver *drv = bs->drv;
5212 int ret;
5214 if (!drv) {
5215 return -ENOMEDIUM;
5218 /* Backing file format doesn't make sense without a backing file */
5219 if (backing_fmt && !backing_file) {
5220 return -EINVAL;
5223 if (require && backing_file && !backing_fmt) {
5224 return -EINVAL;
5227 if (drv->bdrv_change_backing_file != NULL) {
5228 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
5229 } else {
5230 ret = -ENOTSUP;
5233 if (ret == 0) {
5234 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
5235 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
5236 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
5237 backing_file ?: "");
5239 return ret;
5243 * Finds the first non-filter node above bs in the chain between
5244 * active and bs. The returned node is either an immediate parent of
5245 * bs, or there are only filter nodes between the two.
5247 * Returns NULL if bs is not found in active's image chain,
5248 * or if active == bs.
5250 * Returns the bottommost base image if bs == NULL.
5252 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
5253 BlockDriverState *bs)
5255 bs = bdrv_skip_filters(bs);
5256 active = bdrv_skip_filters(active);
5258 while (active) {
5259 BlockDriverState *next = bdrv_backing_chain_next(active);
5260 if (bs == next) {
5261 return active;
5263 active = next;
5266 return NULL;
5269 /* Given a BDS, searches for the base layer. */
5270 BlockDriverState *bdrv_find_base(BlockDriverState *bs)
5272 return bdrv_find_overlay(bs, NULL);
5276 * Return true if at least one of the COW (backing) and filter links
5277 * between @bs and @base is frozen. @errp is set if that's the case.
5278 * @base must be reachable from @bs, or NULL.
5280 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
5281 Error **errp)
5283 BlockDriverState *i;
5284 BdrvChild *child;
5286 for (i = bs; i != base; i = child_bs(child)) {
5287 child = bdrv_filter_or_cow_child(i);
5289 if (child && child->frozen) {
5290 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
5291 child->name, i->node_name, child->bs->node_name);
5292 return true;
5296 return false;
5300 * Freeze all COW (backing) and filter links between @bs and @base.
5301 * If any of the links is already frozen the operation is aborted and
5302 * none of the links are modified.
5303 * @base must be reachable from @bs, or NULL.
5304 * Returns 0 on success. On failure returns < 0 and sets @errp.
5306 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
5307 Error **errp)
5309 BlockDriverState *i;
5310 BdrvChild *child;
5312 if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
5313 return -EPERM;
5316 for (i = bs; i != base; i = child_bs(child)) {
5317 child = bdrv_filter_or_cow_child(i);
5318 if (child && child->bs->never_freeze) {
5319 error_setg(errp, "Cannot freeze '%s' link to '%s'",
5320 child->name, child->bs->node_name);
5321 return -EPERM;
5325 for (i = bs; i != base; i = child_bs(child)) {
5326 child = bdrv_filter_or_cow_child(i);
5327 if (child) {
5328 child->frozen = true;
5332 return 0;
5336 * Unfreeze all COW (backing) and filter links between @bs and @base.
5337 * The caller must ensure that all links are frozen before using this
5338 * function.
5339 * @base must be reachable from @bs, or NULL.
5341 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
5343 BlockDriverState *i;
5344 BdrvChild *child;
5346 for (i = bs; i != base; i = child_bs(child)) {
5347 child = bdrv_filter_or_cow_child(i);
5348 if (child) {
5349 assert(child->frozen);
5350 child->frozen = false;
5356 * Drops images above 'base' up to and including 'top', and sets the image
5357 * above 'top' to have base as its backing file.
5359 * Requires that the overlay to 'top' is opened r/w, so that the backing file
5360 * information in 'bs' can be properly updated.
5362 * E.g., this will convert the following chain:
5363 * bottom <- base <- intermediate <- top <- active
5365 * to
5367 * bottom <- base <- active
5369 * It is allowed for bottom==base, in which case it converts:
5371 * base <- intermediate <- top <- active
5373 * to
5375 * base <- active
5377 * If backing_file_str is non-NULL, it will be used when modifying top's
5378 * overlay image metadata.
5380 * Error conditions:
5381 * if active == top, that is considered an error
5384 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
5385 const char *backing_file_str)
5387 BlockDriverState *explicit_top = top;
5388 bool update_inherits_from;
5389 BdrvChild *c;
5390 Error *local_err = NULL;
5391 int ret = -EIO;
5392 g_autoptr(GSList) updated_children = NULL;
5393 GSList *p;
5395 bdrv_ref(top);
5396 bdrv_subtree_drained_begin(top);
5398 if (!top->drv || !base->drv) {
5399 goto exit;
5402 /* Make sure that base is in the backing chain of top */
5403 if (!bdrv_chain_contains(top, base)) {
5404 goto exit;
5407 /* If 'base' recursively inherits from 'top' then we should set
5408 * base->inherits_from to top->inherits_from after 'top' and all
5409 * other intermediate nodes have been dropped.
5410 * If 'top' is an implicit node (e.g. "commit_top") we should skip
5411 * it because no one inherits from it. We use explicit_top for that. */
5412 explicit_top = bdrv_skip_implicit_filters(explicit_top);
5413 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
5415 /* success - we can delete the intermediate states, and link top->base */
5416 /* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once
5417 * we've figured out how they should work. */
5418 if (!backing_file_str) {
5419 bdrv_refresh_filename(base);
5420 backing_file_str = base->filename;
5423 QLIST_FOREACH(c, &top->parents, next_parent) {
5424 updated_children = g_slist_prepend(updated_children, c);
5428 * It seems correct to pass detach_subchain=true here, but it triggers
5429 * one more yet not fixed bug, when due to nested aio_poll loop we switch to
5430 * another drained section, which modify the graph (for example, removing
5431 * the child, which we keep in updated_children list). So, it's a TODO.
5433 * Note, bug triggered if pass detach_subchain=true here and run
5434 * test-bdrv-drain. test_drop_intermediate_poll() test-case will crash.
5435 * That's a FIXME.
5437 bdrv_replace_node_common(top, base, false, false, &local_err);
5438 if (local_err) {
5439 error_report_err(local_err);
5440 goto exit;
5443 for (p = updated_children; p; p = p->next) {
5444 c = p->data;
5446 if (c->klass->update_filename) {
5447 ret = c->klass->update_filename(c, base, backing_file_str,
5448 &local_err);
5449 if (ret < 0) {
5451 * TODO: Actually, we want to rollback all previous iterations
5452 * of this loop, and (which is almost impossible) previous
5453 * bdrv_replace_node()...
5455 * Note, that c->klass->update_filename may lead to permission
5456 * update, so it's a bad idea to call it inside permission
5457 * update transaction of bdrv_replace_node.
5459 error_report_err(local_err);
5460 goto exit;
5465 if (update_inherits_from) {
5466 base->inherits_from = explicit_top->inherits_from;
5469 ret = 0;
5470 exit:
5471 bdrv_subtree_drained_end(top);
5472 bdrv_unref(top);
5473 return ret;
5477 * Implementation of BlockDriver.bdrv_get_allocated_file_size() that
5478 * sums the size of all data-bearing children. (This excludes backing
5479 * children.)
5481 static int64_t bdrv_sum_allocated_file_size(BlockDriverState *bs)
5483 BdrvChild *child;
5484 int64_t child_size, sum = 0;
5486 QLIST_FOREACH(child, &bs->children, next) {
5487 if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
5488 BDRV_CHILD_FILTERED))
5490 child_size = bdrv_get_allocated_file_size(child->bs);
5491 if (child_size < 0) {
5492 return child_size;
5494 sum += child_size;
5498 return sum;
5502 * Length of a allocated file in bytes. Sparse files are counted by actual
5503 * allocated space. Return < 0 if error or unknown.
5505 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs)
5507 BlockDriver *drv = bs->drv;
5508 if (!drv) {
5509 return -ENOMEDIUM;
5511 if (drv->bdrv_get_allocated_file_size) {
5512 return drv->bdrv_get_allocated_file_size(bs);
5515 if (drv->bdrv_file_open) {
5517 * Protocol drivers default to -ENOTSUP (most of their data is
5518 * not stored in any of their children (if they even have any),
5519 * so there is no generic way to figure it out).
5521 return -ENOTSUP;
5522 } else if (drv->is_filter) {
5523 /* Filter drivers default to the size of their filtered child */
5524 return bdrv_get_allocated_file_size(bdrv_filter_bs(bs));
5525 } else {
5526 /* Other drivers default to summing their children's sizes */
5527 return bdrv_sum_allocated_file_size(bs);
5532 * bdrv_measure:
5533 * @drv: Format driver
5534 * @opts: Creation options for new image
5535 * @in_bs: Existing image containing data for new image (may be NULL)
5536 * @errp: Error object
5537 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
5538 * or NULL on error
5540 * Calculate file size required to create a new image.
5542 * If @in_bs is given then space for allocated clusters and zero clusters
5543 * from that image are included in the calculation. If @opts contains a
5544 * backing file that is shared by @in_bs then backing clusters may be omitted
5545 * from the calculation.
5547 * If @in_bs is NULL then the calculation includes no allocated clusters
5548 * unless a preallocation option is given in @opts.
5550 * Note that @in_bs may use a different BlockDriver from @drv.
5552 * If an error occurs the @errp pointer is set.
5554 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
5555 BlockDriverState *in_bs, Error **errp)
5557 if (!drv->bdrv_measure) {
5558 error_setg(errp, "Block driver '%s' does not support size measurement",
5559 drv->format_name);
5560 return NULL;
5563 return drv->bdrv_measure(opts, in_bs, errp);
5567 * Return number of sectors on success, -errno on error.
5569 int64_t bdrv_nb_sectors(BlockDriverState *bs)
5571 BlockDriver *drv = bs->drv;
5573 if (!drv)
5574 return -ENOMEDIUM;
5576 if (drv->has_variable_length) {
5577 int ret = refresh_total_sectors(bs, bs->total_sectors);
5578 if (ret < 0) {
5579 return ret;
5582 return bs->total_sectors;
5586 * Return length in bytes on success, -errno on error.
5587 * The length is always a multiple of BDRV_SECTOR_SIZE.
5589 int64_t bdrv_getlength(BlockDriverState *bs)
5591 int64_t ret = bdrv_nb_sectors(bs);
5593 if (ret < 0) {
5594 return ret;
5596 if (ret > INT64_MAX / BDRV_SECTOR_SIZE) {
5597 return -EFBIG;
5599 return ret * BDRV_SECTOR_SIZE;
5602 /* return 0 as number of sectors if no device present or error */
5603 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
5605 int64_t nb_sectors = bdrv_nb_sectors(bs);
5607 *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
5610 bool bdrv_is_sg(BlockDriverState *bs)
5612 return bs->sg;
5616 * Return whether the given node supports compressed writes.
5618 bool bdrv_supports_compressed_writes(BlockDriverState *bs)
5620 BlockDriverState *filtered;
5622 if (!bs->drv || !block_driver_can_compress(bs->drv)) {
5623 return false;
5626 filtered = bdrv_filter_bs(bs);
5627 if (filtered) {
5629 * Filters can only forward compressed writes, so we have to
5630 * check the child.
5632 return bdrv_supports_compressed_writes(filtered);
5635 return true;
5638 const char *bdrv_get_format_name(BlockDriverState *bs)
5640 return bs->drv ? bs->drv->format_name : NULL;
5643 static int qsort_strcmp(const void *a, const void *b)
5645 return strcmp(*(char *const *)a, *(char *const *)b);
5648 void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
5649 void *opaque, bool read_only)
5651 BlockDriver *drv;
5652 int count = 0;
5653 int i;
5654 const char **formats = NULL;
5656 QLIST_FOREACH(drv, &bdrv_drivers, list) {
5657 if (drv->format_name) {
5658 bool found = false;
5659 int i = count;
5661 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) {
5662 continue;
5665 while (formats && i && !found) {
5666 found = !strcmp(formats[--i], drv->format_name);
5669 if (!found) {
5670 formats = g_renew(const char *, formats, count + 1);
5671 formats[count++] = drv->format_name;
5676 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) {
5677 const char *format_name = block_driver_modules[i].format_name;
5679 if (format_name) {
5680 bool found = false;
5681 int j = count;
5683 if (use_bdrv_whitelist &&
5684 !bdrv_format_is_whitelisted(format_name, read_only)) {
5685 continue;
5688 while (formats && j && !found) {
5689 found = !strcmp(formats[--j], format_name);
5692 if (!found) {
5693 formats = g_renew(const char *, formats, count + 1);
5694 formats[count++] = format_name;
5699 qsort(formats, count, sizeof(formats[0]), qsort_strcmp);
5701 for (i = 0; i < count; i++) {
5702 it(opaque, formats[i]);
5705 g_free(formats);
5708 /* This function is to find a node in the bs graph */
5709 BlockDriverState *bdrv_find_node(const char *node_name)
5711 BlockDriverState *bs;
5713 assert(node_name);
5715 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5716 if (!strcmp(node_name, bs->node_name)) {
5717 return bs;
5720 return NULL;
5723 /* Put this QMP function here so it can access the static graph_bdrv_states. */
5724 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
5725 Error **errp)
5727 BlockDeviceInfoList *list;
5728 BlockDriverState *bs;
5730 list = NULL;
5731 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5732 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
5733 if (!info) {
5734 qapi_free_BlockDeviceInfoList(list);
5735 return NULL;
5737 QAPI_LIST_PREPEND(list, info);
5740 return list;
5743 typedef struct XDbgBlockGraphConstructor {
5744 XDbgBlockGraph *graph;
5745 GHashTable *graph_nodes;
5746 } XDbgBlockGraphConstructor;
5748 static XDbgBlockGraphConstructor *xdbg_graph_new(void)
5750 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1);
5752 gr->graph = g_new0(XDbgBlockGraph, 1);
5753 gr->graph_nodes = g_hash_table_new(NULL, NULL);
5755 return gr;
5758 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr)
5760 XDbgBlockGraph *graph = gr->graph;
5762 g_hash_table_destroy(gr->graph_nodes);
5763 g_free(gr);
5765 return graph;
5768 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node)
5770 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node);
5772 if (ret != 0) {
5773 return ret;
5777 * Start counting from 1, not 0, because 0 interferes with not-found (NULL)
5778 * answer of g_hash_table_lookup.
5780 ret = g_hash_table_size(gr->graph_nodes) + 1;
5781 g_hash_table_insert(gr->graph_nodes, node, (void *)ret);
5783 return ret;
5786 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node,
5787 XDbgBlockGraphNodeType type, const char *name)
5789 XDbgBlockGraphNode *n;
5791 n = g_new0(XDbgBlockGraphNode, 1);
5793 n->id = xdbg_graph_node_num(gr, node);
5794 n->type = type;
5795 n->name = g_strdup(name);
5797 QAPI_LIST_PREPEND(gr->graph->nodes, n);
5800 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent,
5801 const BdrvChild *child)
5803 BlockPermission qapi_perm;
5804 XDbgBlockGraphEdge *edge;
5806 edge = g_new0(XDbgBlockGraphEdge, 1);
5808 edge->parent = xdbg_graph_node_num(gr, parent);
5809 edge->child = xdbg_graph_node_num(gr, child->bs);
5810 edge->name = g_strdup(child->name);
5812 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) {
5813 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm);
5815 if (flag & child->perm) {
5816 QAPI_LIST_PREPEND(edge->perm, qapi_perm);
5818 if (flag & child->shared_perm) {
5819 QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm);
5823 QAPI_LIST_PREPEND(gr->graph->edges, edge);
5827 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp)
5829 BlockBackend *blk;
5830 BlockJob *job;
5831 BlockDriverState *bs;
5832 BdrvChild *child;
5833 XDbgBlockGraphConstructor *gr = xdbg_graph_new();
5835 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
5836 char *allocated_name = NULL;
5837 const char *name = blk_name(blk);
5839 if (!*name) {
5840 name = allocated_name = blk_get_attached_dev_id(blk);
5842 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND,
5843 name);
5844 g_free(allocated_name);
5845 if (blk_root(blk)) {
5846 xdbg_graph_add_edge(gr, blk, blk_root(blk));
5850 for (job = block_job_next(NULL); job; job = block_job_next(job)) {
5851 GSList *el;
5853 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB,
5854 job->job.id);
5855 for (el = job->nodes; el; el = el->next) {
5856 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data);
5860 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5861 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER,
5862 bs->node_name);
5863 QLIST_FOREACH(child, &bs->children, next) {
5864 xdbg_graph_add_edge(gr, bs, child);
5868 return xdbg_graph_finalize(gr);
5871 BlockDriverState *bdrv_lookup_bs(const char *device,
5872 const char *node_name,
5873 Error **errp)
5875 BlockBackend *blk;
5876 BlockDriverState *bs;
5878 if (device) {
5879 blk = blk_by_name(device);
5881 if (blk) {
5882 bs = blk_bs(blk);
5883 if (!bs) {
5884 error_setg(errp, "Device '%s' has no medium", device);
5887 return bs;
5891 if (node_name) {
5892 bs = bdrv_find_node(node_name);
5894 if (bs) {
5895 return bs;
5899 error_setg(errp, "Cannot find device=\'%s\' nor node-name=\'%s\'",
5900 device ? device : "",
5901 node_name ? node_name : "");
5902 return NULL;
5905 /* If 'base' is in the same chain as 'top', return true. Otherwise,
5906 * return false. If either argument is NULL, return false. */
5907 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
5909 while (top && top != base) {
5910 top = bdrv_filter_or_cow_bs(top);
5913 return top != NULL;
5916 BlockDriverState *bdrv_next_node(BlockDriverState *bs)
5918 if (!bs) {
5919 return QTAILQ_FIRST(&graph_bdrv_states);
5921 return QTAILQ_NEXT(bs, node_list);
5924 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs)
5926 if (!bs) {
5927 return QTAILQ_FIRST(&all_bdrv_states);
5929 return QTAILQ_NEXT(bs, bs_list);
5932 const char *bdrv_get_node_name(const BlockDriverState *bs)
5934 return bs->node_name;
5937 const char *bdrv_get_parent_name(const BlockDriverState *bs)
5939 BdrvChild *c;
5940 const char *name;
5942 /* If multiple parents have a name, just pick the first one. */
5943 QLIST_FOREACH(c, &bs->parents, next_parent) {
5944 if (c->klass->get_name) {
5945 name = c->klass->get_name(c);
5946 if (name && *name) {
5947 return name;
5952 return NULL;
5955 /* TODO check what callers really want: bs->node_name or blk_name() */
5956 const char *bdrv_get_device_name(const BlockDriverState *bs)
5958 return bdrv_get_parent_name(bs) ?: "";
5961 /* This can be used to identify nodes that might not have a device
5962 * name associated. Since node and device names live in the same
5963 * namespace, the result is unambiguous. The exception is if both are
5964 * absent, then this returns an empty (non-null) string. */
5965 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
5967 return bdrv_get_parent_name(bs) ?: bs->node_name;
5970 int bdrv_get_flags(BlockDriverState *bs)
5972 return bs->open_flags;
5975 int bdrv_has_zero_init_1(BlockDriverState *bs)
5977 return 1;
5980 int bdrv_has_zero_init(BlockDriverState *bs)
5982 BlockDriverState *filtered;
5984 if (!bs->drv) {
5985 return 0;
5988 /* If BS is a copy on write image, it is initialized to
5989 the contents of the base image, which may not be zeroes. */
5990 if (bdrv_cow_child(bs)) {
5991 return 0;
5993 if (bs->drv->bdrv_has_zero_init) {
5994 return bs->drv->bdrv_has_zero_init(bs);
5997 filtered = bdrv_filter_bs(bs);
5998 if (filtered) {
5999 return bdrv_has_zero_init(filtered);
6002 /* safe default */
6003 return 0;
6006 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
6008 if (!(bs->open_flags & BDRV_O_UNMAP)) {
6009 return false;
6012 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
6015 void bdrv_get_backing_filename(BlockDriverState *bs,
6016 char *filename, int filename_size)
6018 pstrcpy(filename, filename_size, bs->backing_file);
6021 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
6023 int ret;
6024 BlockDriver *drv = bs->drv;
6025 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
6026 if (!drv) {
6027 return -ENOMEDIUM;
6029 if (!drv->bdrv_get_info) {
6030 BlockDriverState *filtered = bdrv_filter_bs(bs);
6031 if (filtered) {
6032 return bdrv_get_info(filtered, bdi);
6034 return -ENOTSUP;
6036 memset(bdi, 0, sizeof(*bdi));
6037 ret = drv->bdrv_get_info(bs, bdi);
6038 if (ret < 0) {
6039 return ret;
6042 if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) {
6043 return -EINVAL;
6046 return 0;
6049 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
6050 Error **errp)
6052 BlockDriver *drv = bs->drv;
6053 if (drv && drv->bdrv_get_specific_info) {
6054 return drv->bdrv_get_specific_info(bs, errp);
6056 return NULL;
6059 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs)
6061 BlockDriver *drv = bs->drv;
6062 if (!drv || !drv->bdrv_get_specific_stats) {
6063 return NULL;
6065 return drv->bdrv_get_specific_stats(bs);
6068 void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event)
6070 if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) {
6071 return;
6074 bs->drv->bdrv_debug_event(bs, event);
6077 static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs)
6079 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
6080 bs = bdrv_primary_bs(bs);
6083 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
6084 assert(bs->drv->bdrv_debug_remove_breakpoint);
6085 return bs;
6088 return NULL;
6091 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event,
6092 const char *tag)
6094 bs = bdrv_find_debug_node(bs);
6095 if (bs) {
6096 return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
6099 return -ENOTSUP;
6102 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
6104 bs = bdrv_find_debug_node(bs);
6105 if (bs) {
6106 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
6109 return -ENOTSUP;
6112 int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
6114 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
6115 bs = bdrv_primary_bs(bs);
6118 if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
6119 return bs->drv->bdrv_debug_resume(bs, tag);
6122 return -ENOTSUP;
6125 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
6127 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
6128 bs = bdrv_primary_bs(bs);
6131 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
6132 return bs->drv->bdrv_debug_is_suspended(bs, tag);
6135 return false;
6138 /* backing_file can either be relative, or absolute, or a protocol. If it is
6139 * relative, it must be relative to the chain. So, passing in bs->filename
6140 * from a BDS as backing_file should not be done, as that may be relative to
6141 * the CWD rather than the chain. */
6142 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
6143 const char *backing_file)
6145 char *filename_full = NULL;
6146 char *backing_file_full = NULL;
6147 char *filename_tmp = NULL;
6148 int is_protocol = 0;
6149 bool filenames_refreshed = false;
6150 BlockDriverState *curr_bs = NULL;
6151 BlockDriverState *retval = NULL;
6152 BlockDriverState *bs_below;
6154 if (!bs || !bs->drv || !backing_file) {
6155 return NULL;
6158 filename_full = g_malloc(PATH_MAX);
6159 backing_file_full = g_malloc(PATH_MAX);
6161 is_protocol = path_has_protocol(backing_file);
6164 * Being largely a legacy function, skip any filters here
6165 * (because filters do not have normal filenames, so they cannot
6166 * match anyway; and allowing json:{} filenames is a bit out of
6167 * scope).
6169 for (curr_bs = bdrv_skip_filters(bs);
6170 bdrv_cow_child(curr_bs) != NULL;
6171 curr_bs = bs_below)
6173 bs_below = bdrv_backing_chain_next(curr_bs);
6175 if (bdrv_backing_overridden(curr_bs)) {
6177 * If the backing file was overridden, we can only compare
6178 * directly against the backing node's filename.
6181 if (!filenames_refreshed) {
6183 * This will automatically refresh all of the
6184 * filenames in the rest of the backing chain, so we
6185 * only need to do this once.
6187 bdrv_refresh_filename(bs_below);
6188 filenames_refreshed = true;
6191 if (strcmp(backing_file, bs_below->filename) == 0) {
6192 retval = bs_below;
6193 break;
6195 } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
6197 * If either of the filename paths is actually a protocol, then
6198 * compare unmodified paths; otherwise make paths relative.
6200 char *backing_file_full_ret;
6202 if (strcmp(backing_file, curr_bs->backing_file) == 0) {
6203 retval = bs_below;
6204 break;
6206 /* Also check against the full backing filename for the image */
6207 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs,
6208 NULL);
6209 if (backing_file_full_ret) {
6210 bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
6211 g_free(backing_file_full_ret);
6212 if (equal) {
6213 retval = bs_below;
6214 break;
6217 } else {
6218 /* If not an absolute filename path, make it relative to the current
6219 * image's filename path */
6220 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
6221 NULL);
6222 /* We are going to compare canonicalized absolute pathnames */
6223 if (!filename_tmp || !realpath(filename_tmp, filename_full)) {
6224 g_free(filename_tmp);
6225 continue;
6227 g_free(filename_tmp);
6229 /* We need to make sure the backing filename we are comparing against
6230 * is relative to the current image filename (or absolute) */
6231 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
6232 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) {
6233 g_free(filename_tmp);
6234 continue;
6236 g_free(filename_tmp);
6238 if (strcmp(backing_file_full, filename_full) == 0) {
6239 retval = bs_below;
6240 break;
6245 g_free(filename_full);
6246 g_free(backing_file_full);
6247 return retval;
6250 void bdrv_init(void)
6252 #ifdef CONFIG_BDRV_WHITELIST_TOOLS
6253 use_bdrv_whitelist = 1;
6254 #endif
6255 module_call_init(MODULE_INIT_BLOCK);
6258 void bdrv_init_with_whitelist(void)
6260 use_bdrv_whitelist = 1;
6261 bdrv_init();
6264 int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp)
6266 BdrvChild *child, *parent;
6267 Error *local_err = NULL;
6268 int ret;
6269 BdrvDirtyBitmap *bm;
6271 if (!bs->drv) {
6272 return -ENOMEDIUM;
6275 QLIST_FOREACH(child, &bs->children, next) {
6276 bdrv_co_invalidate_cache(child->bs, &local_err);
6277 if (local_err) {
6278 error_propagate(errp, local_err);
6279 return -EINVAL;
6284 * Update permissions, they may differ for inactive nodes.
6286 * Note that the required permissions of inactive images are always a
6287 * subset of the permissions required after activating the image. This
6288 * allows us to just get the permissions upfront without restricting
6289 * drv->bdrv_invalidate_cache().
6291 * It also means that in error cases, we don't have to try and revert to
6292 * the old permissions (which is an operation that could fail, too). We can
6293 * just keep the extended permissions for the next time that an activation
6294 * of the image is tried.
6296 if (bs->open_flags & BDRV_O_INACTIVE) {
6297 bs->open_flags &= ~BDRV_O_INACTIVE;
6298 ret = bdrv_refresh_perms(bs, errp);
6299 if (ret < 0) {
6300 bs->open_flags |= BDRV_O_INACTIVE;
6301 return ret;
6304 if (bs->drv->bdrv_co_invalidate_cache) {
6305 bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
6306 if (local_err) {
6307 bs->open_flags |= BDRV_O_INACTIVE;
6308 error_propagate(errp, local_err);
6309 return -EINVAL;
6313 FOR_EACH_DIRTY_BITMAP(bs, bm) {
6314 bdrv_dirty_bitmap_skip_store(bm, false);
6317 ret = refresh_total_sectors(bs, bs->total_sectors);
6318 if (ret < 0) {
6319 bs->open_flags |= BDRV_O_INACTIVE;
6320 error_setg_errno(errp, -ret, "Could not refresh total sector count");
6321 return ret;
6325 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6326 if (parent->klass->activate) {
6327 parent->klass->activate(parent, &local_err);
6328 if (local_err) {
6329 bs->open_flags |= BDRV_O_INACTIVE;
6330 error_propagate(errp, local_err);
6331 return -EINVAL;
6336 return 0;
6339 void bdrv_invalidate_cache_all(Error **errp)
6341 BlockDriverState *bs;
6342 BdrvNextIterator it;
6344 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
6345 AioContext *aio_context = bdrv_get_aio_context(bs);
6346 int ret;
6348 aio_context_acquire(aio_context);
6349 ret = bdrv_invalidate_cache(bs, errp);
6350 aio_context_release(aio_context);
6351 if (ret < 0) {
6352 bdrv_next_cleanup(&it);
6353 return;
6358 static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
6360 BdrvChild *parent;
6362 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6363 if (parent->klass->parent_is_bds) {
6364 BlockDriverState *parent_bs = parent->opaque;
6365 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) {
6366 return true;
6371 return false;
6374 static int bdrv_inactivate_recurse(BlockDriverState *bs)
6376 BdrvChild *child, *parent;
6377 int ret;
6378 uint64_t cumulative_perms, cumulative_shared_perms;
6380 if (!bs->drv) {
6381 return -ENOMEDIUM;
6384 /* Make sure that we don't inactivate a child before its parent.
6385 * It will be covered by recursion from the yet active parent. */
6386 if (bdrv_has_bds_parent(bs, true)) {
6387 return 0;
6390 assert(!(bs->open_flags & BDRV_O_INACTIVE));
6392 /* Inactivate this node */
6393 if (bs->drv->bdrv_inactivate) {
6394 ret = bs->drv->bdrv_inactivate(bs);
6395 if (ret < 0) {
6396 return ret;
6400 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6401 if (parent->klass->inactivate) {
6402 ret = parent->klass->inactivate(parent);
6403 if (ret < 0) {
6404 return ret;
6409 bdrv_get_cumulative_perm(bs, &cumulative_perms,
6410 &cumulative_shared_perms);
6411 if (cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
6412 /* Our inactive parents still need write access. Inactivation failed. */
6413 return -EPERM;
6416 bs->open_flags |= BDRV_O_INACTIVE;
6419 * Update permissions, they may differ for inactive nodes.
6420 * We only tried to loosen restrictions, so errors are not fatal, ignore
6421 * them.
6423 bdrv_refresh_perms(bs, NULL);
6425 /* Recursively inactivate children */
6426 QLIST_FOREACH(child, &bs->children, next) {
6427 ret = bdrv_inactivate_recurse(child->bs);
6428 if (ret < 0) {
6429 return ret;
6433 return 0;
6436 int bdrv_inactivate_all(void)
6438 BlockDriverState *bs = NULL;
6439 BdrvNextIterator it;
6440 int ret = 0;
6441 GSList *aio_ctxs = NULL, *ctx;
6443 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
6444 AioContext *aio_context = bdrv_get_aio_context(bs);
6446 if (!g_slist_find(aio_ctxs, aio_context)) {
6447 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
6448 aio_context_acquire(aio_context);
6452 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
6453 /* Nodes with BDS parents are covered by recursion from the last
6454 * parent that gets inactivated. Don't inactivate them a second
6455 * time if that has already happened. */
6456 if (bdrv_has_bds_parent(bs, false)) {
6457 continue;
6459 ret = bdrv_inactivate_recurse(bs);
6460 if (ret < 0) {
6461 bdrv_next_cleanup(&it);
6462 goto out;
6466 out:
6467 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
6468 AioContext *aio_context = ctx->data;
6469 aio_context_release(aio_context);
6471 g_slist_free(aio_ctxs);
6473 return ret;
6476 /**************************************************************/
6477 /* removable device support */
6480 * Return TRUE if the media is present
6482 bool bdrv_is_inserted(BlockDriverState *bs)
6484 BlockDriver *drv = bs->drv;
6485 BdrvChild *child;
6487 if (!drv) {
6488 return false;
6490 if (drv->bdrv_is_inserted) {
6491 return drv->bdrv_is_inserted(bs);
6493 QLIST_FOREACH(child, &bs->children, next) {
6494 if (!bdrv_is_inserted(child->bs)) {
6495 return false;
6498 return true;
6502 * If eject_flag is TRUE, eject the media. Otherwise, close the tray
6504 void bdrv_eject(BlockDriverState *bs, bool eject_flag)
6506 BlockDriver *drv = bs->drv;
6508 if (drv && drv->bdrv_eject) {
6509 drv->bdrv_eject(bs, eject_flag);
6514 * Lock or unlock the media (if it is locked, the user won't be able
6515 * to eject it manually).
6517 void bdrv_lock_medium(BlockDriverState *bs, bool locked)
6519 BlockDriver *drv = bs->drv;
6521 trace_bdrv_lock_medium(bs, locked);
6523 if (drv && drv->bdrv_lock_medium) {
6524 drv->bdrv_lock_medium(bs, locked);
6528 /* Get a reference to bs */
6529 void bdrv_ref(BlockDriverState *bs)
6531 bs->refcnt++;
6534 /* Release a previously grabbed reference to bs.
6535 * If after releasing, reference count is zero, the BlockDriverState is
6536 * deleted. */
6537 void bdrv_unref(BlockDriverState *bs)
6539 if (!bs) {
6540 return;
6542 assert(bs->refcnt > 0);
6543 if (--bs->refcnt == 0) {
6544 bdrv_delete(bs);
6548 struct BdrvOpBlocker {
6549 Error *reason;
6550 QLIST_ENTRY(BdrvOpBlocker) list;
6553 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
6555 BdrvOpBlocker *blocker;
6556 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6557 if (!QLIST_EMPTY(&bs->op_blockers[op])) {
6558 blocker = QLIST_FIRST(&bs->op_blockers[op]);
6559 error_propagate_prepend(errp, error_copy(blocker->reason),
6560 "Node '%s' is busy: ",
6561 bdrv_get_device_or_node_name(bs));
6562 return true;
6564 return false;
6567 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
6569 BdrvOpBlocker *blocker;
6570 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6572 blocker = g_new0(BdrvOpBlocker, 1);
6573 blocker->reason = reason;
6574 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
6577 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
6579 BdrvOpBlocker *blocker, *next;
6580 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6581 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
6582 if (blocker->reason == reason) {
6583 QLIST_REMOVE(blocker, list);
6584 g_free(blocker);
6589 void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
6591 int i;
6592 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6593 bdrv_op_block(bs, i, reason);
6597 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
6599 int i;
6600 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6601 bdrv_op_unblock(bs, i, reason);
6605 bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
6607 int i;
6609 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6610 if (!QLIST_EMPTY(&bs->op_blockers[i])) {
6611 return false;
6614 return true;
6617 void bdrv_img_create(const char *filename, const char *fmt,
6618 const char *base_filename, const char *base_fmt,
6619 char *options, uint64_t img_size, int flags, bool quiet,
6620 Error **errp)
6622 QemuOptsList *create_opts = NULL;
6623 QemuOpts *opts = NULL;
6624 const char *backing_fmt, *backing_file;
6625 int64_t size;
6626 BlockDriver *drv, *proto_drv;
6627 Error *local_err = NULL;
6628 int ret = 0;
6630 /* Find driver and parse its options */
6631 drv = bdrv_find_format(fmt);
6632 if (!drv) {
6633 error_setg(errp, "Unknown file format '%s'", fmt);
6634 return;
6637 proto_drv = bdrv_find_protocol(filename, true, errp);
6638 if (!proto_drv) {
6639 return;
6642 if (!drv->create_opts) {
6643 error_setg(errp, "Format driver '%s' does not support image creation",
6644 drv->format_name);
6645 return;
6648 if (!proto_drv->create_opts) {
6649 error_setg(errp, "Protocol driver '%s' does not support image creation",
6650 proto_drv->format_name);
6651 return;
6654 /* Create parameter list */
6655 create_opts = qemu_opts_append(create_opts, drv->create_opts);
6656 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
6658 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
6660 /* Parse -o options */
6661 if (options) {
6662 if (!qemu_opts_do_parse(opts, options, NULL, errp)) {
6663 goto out;
6667 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) {
6668 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort);
6669 } else if (img_size != UINT64_C(-1)) {
6670 error_setg(errp, "The image size must be specified only once");
6671 goto out;
6674 if (base_filename) {
6675 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename,
6676 NULL)) {
6677 error_setg(errp, "Backing file not supported for file format '%s'",
6678 fmt);
6679 goto out;
6683 if (base_fmt) {
6684 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) {
6685 error_setg(errp, "Backing file format not supported for file "
6686 "format '%s'", fmt);
6687 goto out;
6691 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
6692 if (backing_file) {
6693 if (!strcmp(filename, backing_file)) {
6694 error_setg(errp, "Error: Trying to create an image with the "
6695 "same filename as the backing file");
6696 goto out;
6698 if (backing_file[0] == '\0') {
6699 error_setg(errp, "Expected backing file name, got empty string");
6700 goto out;
6704 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
6706 /* The size for the image must always be specified, unless we have a backing
6707 * file and we have not been forbidden from opening it. */
6708 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
6709 if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
6710 BlockDriverState *bs;
6711 char *full_backing;
6712 int back_flags;
6713 QDict *backing_options = NULL;
6715 full_backing =
6716 bdrv_get_full_backing_filename_from_filename(filename, backing_file,
6717 &local_err);
6718 if (local_err) {
6719 goto out;
6721 assert(full_backing);
6724 * No need to do I/O here, which allows us to open encrypted
6725 * backing images without needing the secret
6727 back_flags = flags;
6728 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
6729 back_flags |= BDRV_O_NO_IO;
6731 backing_options = qdict_new();
6732 if (backing_fmt) {
6733 qdict_put_str(backing_options, "driver", backing_fmt);
6735 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
6737 bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
6738 &local_err);
6739 g_free(full_backing);
6740 if (!bs) {
6741 error_append_hint(&local_err, "Could not open backing image.\n");
6742 goto out;
6743 } else {
6744 if (!backing_fmt) {
6745 error_setg(&local_err,
6746 "Backing file specified without backing format");
6747 error_append_hint(&local_err, "Detected format of %s.",
6748 bs->drv->format_name);
6749 goto out;
6751 if (size == -1) {
6752 /* Opened BS, have no size */
6753 size = bdrv_getlength(bs);
6754 if (size < 0) {
6755 error_setg_errno(errp, -size, "Could not get size of '%s'",
6756 backing_file);
6757 bdrv_unref(bs);
6758 goto out;
6760 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
6762 bdrv_unref(bs);
6764 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
6765 } else if (backing_file && !backing_fmt) {
6766 error_setg(&local_err,
6767 "Backing file specified without backing format");
6768 goto out;
6771 if (size == -1) {
6772 error_setg(errp, "Image creation needs a size parameter");
6773 goto out;
6776 if (!quiet) {
6777 printf("Formatting '%s', fmt=%s ", filename, fmt);
6778 qemu_opts_print(opts, " ");
6779 puts("");
6780 fflush(stdout);
6783 ret = bdrv_create(drv, filename, opts, &local_err);
6785 if (ret == -EFBIG) {
6786 /* This is generally a better message than whatever the driver would
6787 * deliver (especially because of the cluster_size_hint), since that
6788 * is most probably not much different from "image too large". */
6789 const char *cluster_size_hint = "";
6790 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) {
6791 cluster_size_hint = " (try using a larger cluster size)";
6793 error_setg(errp, "The image size is too large for file format '%s'"
6794 "%s", fmt, cluster_size_hint);
6795 error_free(local_err);
6796 local_err = NULL;
6799 out:
6800 qemu_opts_del(opts);
6801 qemu_opts_free(create_opts);
6802 error_propagate(errp, local_err);
6805 AioContext *bdrv_get_aio_context(BlockDriverState *bs)
6807 return bs ? bs->aio_context : qemu_get_aio_context();
6810 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs)
6812 Coroutine *self = qemu_coroutine_self();
6813 AioContext *old_ctx = qemu_coroutine_get_aio_context(self);
6814 AioContext *new_ctx;
6817 * Increase bs->in_flight to ensure that this operation is completed before
6818 * moving the node to a different AioContext. Read new_ctx only afterwards.
6820 bdrv_inc_in_flight(bs);
6822 new_ctx = bdrv_get_aio_context(bs);
6823 aio_co_reschedule_self(new_ctx);
6824 return old_ctx;
6827 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx)
6829 aio_co_reschedule_self(old_ctx);
6830 bdrv_dec_in_flight(bs);
6833 void coroutine_fn bdrv_co_lock(BlockDriverState *bs)
6835 AioContext *ctx = bdrv_get_aio_context(bs);
6837 /* In the main thread, bs->aio_context won't change concurrently */
6838 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
6841 * We're in coroutine context, so we already hold the lock of the main
6842 * loop AioContext. Don't lock it twice to avoid deadlocks.
6844 assert(qemu_in_coroutine());
6845 if (ctx != qemu_get_aio_context()) {
6846 aio_context_acquire(ctx);
6850 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs)
6852 AioContext *ctx = bdrv_get_aio_context(bs);
6854 assert(qemu_in_coroutine());
6855 if (ctx != qemu_get_aio_context()) {
6856 aio_context_release(ctx);
6860 void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co)
6862 aio_co_enter(bdrv_get_aio_context(bs), co);
6865 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
6867 QLIST_REMOVE(ban, list);
6868 g_free(ban);
6871 static void bdrv_detach_aio_context(BlockDriverState *bs)
6873 BdrvAioNotifier *baf, *baf_tmp;
6875 assert(!bs->walking_aio_notifiers);
6876 bs->walking_aio_notifiers = true;
6877 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
6878 if (baf->deleted) {
6879 bdrv_do_remove_aio_context_notifier(baf);
6880 } else {
6881 baf->detach_aio_context(baf->opaque);
6884 /* Never mind iterating again to check for ->deleted. bdrv_close() will
6885 * remove remaining aio notifiers if we aren't called again.
6887 bs->walking_aio_notifiers = false;
6889 if (bs->drv && bs->drv->bdrv_detach_aio_context) {
6890 bs->drv->bdrv_detach_aio_context(bs);
6893 if (bs->quiesce_counter) {
6894 aio_enable_external(bs->aio_context);
6896 bs->aio_context = NULL;
6899 static void bdrv_attach_aio_context(BlockDriverState *bs,
6900 AioContext *new_context)
6902 BdrvAioNotifier *ban, *ban_tmp;
6904 if (bs->quiesce_counter) {
6905 aio_disable_external(new_context);
6908 bs->aio_context = new_context;
6910 if (bs->drv && bs->drv->bdrv_attach_aio_context) {
6911 bs->drv->bdrv_attach_aio_context(bs, new_context);
6914 assert(!bs->walking_aio_notifiers);
6915 bs->walking_aio_notifiers = true;
6916 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) {
6917 if (ban->deleted) {
6918 bdrv_do_remove_aio_context_notifier(ban);
6919 } else {
6920 ban->attached_aio_context(new_context, ban->opaque);
6923 bs->walking_aio_notifiers = false;
6927 * Changes the AioContext used for fd handlers, timers, and BHs by this
6928 * BlockDriverState and all its children and parents.
6930 * Must be called from the main AioContext.
6932 * The caller must own the AioContext lock for the old AioContext of bs, but it
6933 * must not own the AioContext lock for new_context (unless new_context is the
6934 * same as the current context of bs).
6936 * @ignore will accumulate all visited BdrvChild object. The caller is
6937 * responsible for freeing the list afterwards.
6939 void bdrv_set_aio_context_ignore(BlockDriverState *bs,
6940 AioContext *new_context, GSList **ignore)
6942 AioContext *old_context = bdrv_get_aio_context(bs);
6943 GSList *children_to_process = NULL;
6944 GSList *parents_to_process = NULL;
6945 GSList *entry;
6946 BdrvChild *child, *parent;
6948 g_assert(qemu_get_current_aio_context() == qemu_get_aio_context());
6950 if (old_context == new_context) {
6951 return;
6954 bdrv_drained_begin(bs);
6956 QLIST_FOREACH(child, &bs->children, next) {
6957 if (g_slist_find(*ignore, child)) {
6958 continue;
6960 *ignore = g_slist_prepend(*ignore, child);
6961 children_to_process = g_slist_prepend(children_to_process, child);
6964 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6965 if (g_slist_find(*ignore, parent)) {
6966 continue;
6968 *ignore = g_slist_prepend(*ignore, parent);
6969 parents_to_process = g_slist_prepend(parents_to_process, parent);
6972 for (entry = children_to_process;
6973 entry != NULL;
6974 entry = g_slist_next(entry)) {
6975 child = entry->data;
6976 bdrv_set_aio_context_ignore(child->bs, new_context, ignore);
6978 g_slist_free(children_to_process);
6980 for (entry = parents_to_process;
6981 entry != NULL;
6982 entry = g_slist_next(entry)) {
6983 parent = entry->data;
6984 assert(parent->klass->set_aio_ctx);
6985 parent->klass->set_aio_ctx(parent, new_context, ignore);
6987 g_slist_free(parents_to_process);
6989 bdrv_detach_aio_context(bs);
6991 /* Acquire the new context, if necessary */
6992 if (qemu_get_aio_context() != new_context) {
6993 aio_context_acquire(new_context);
6996 bdrv_attach_aio_context(bs, new_context);
6999 * If this function was recursively called from
7000 * bdrv_set_aio_context_ignore(), there may be nodes in the
7001 * subtree that have not yet been moved to the new AioContext.
7002 * Release the old one so bdrv_drained_end() can poll them.
7004 if (qemu_get_aio_context() != old_context) {
7005 aio_context_release(old_context);
7008 bdrv_drained_end(bs);
7010 if (qemu_get_aio_context() != old_context) {
7011 aio_context_acquire(old_context);
7013 if (qemu_get_aio_context() != new_context) {
7014 aio_context_release(new_context);
7018 static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx,
7019 GSList **ignore, Error **errp)
7021 if (g_slist_find(*ignore, c)) {
7022 return true;
7024 *ignore = g_slist_prepend(*ignore, c);
7027 * A BdrvChildClass that doesn't handle AioContext changes cannot
7028 * tolerate any AioContext changes
7030 if (!c->klass->can_set_aio_ctx) {
7031 char *user = bdrv_child_user_desc(c);
7032 error_setg(errp, "Changing iothreads is not supported by %s", user);
7033 g_free(user);
7034 return false;
7036 if (!c->klass->can_set_aio_ctx(c, ctx, ignore, errp)) {
7037 assert(!errp || *errp);
7038 return false;
7040 return true;
7043 bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
7044 GSList **ignore, Error **errp)
7046 if (g_slist_find(*ignore, c)) {
7047 return true;
7049 *ignore = g_slist_prepend(*ignore, c);
7050 return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp);
7053 /* @ignore will accumulate all visited BdrvChild object. The caller is
7054 * responsible for freeing the list afterwards. */
7055 bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
7056 GSList **ignore, Error **errp)
7058 BdrvChild *c;
7060 if (bdrv_get_aio_context(bs) == ctx) {
7061 return true;
7064 QLIST_FOREACH(c, &bs->parents, next_parent) {
7065 if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) {
7066 return false;
7069 QLIST_FOREACH(c, &bs->children, next) {
7070 if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) {
7071 return false;
7075 return true;
7078 int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
7079 BdrvChild *ignore_child, Error **errp)
7081 GSList *ignore;
7082 bool ret;
7084 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
7085 ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp);
7086 g_slist_free(ignore);
7088 if (!ret) {
7089 return -EPERM;
7092 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
7093 bdrv_set_aio_context_ignore(bs, ctx, &ignore);
7094 g_slist_free(ignore);
7096 return 0;
7099 int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
7100 Error **errp)
7102 return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp);
7105 void bdrv_add_aio_context_notifier(BlockDriverState *bs,
7106 void (*attached_aio_context)(AioContext *new_context, void *opaque),
7107 void (*detach_aio_context)(void *opaque), void *opaque)
7109 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1);
7110 *ban = (BdrvAioNotifier){
7111 .attached_aio_context = attached_aio_context,
7112 .detach_aio_context = detach_aio_context,
7113 .opaque = opaque
7116 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list);
7119 void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
7120 void (*attached_aio_context)(AioContext *,
7121 void *),
7122 void (*detach_aio_context)(void *),
7123 void *opaque)
7125 BdrvAioNotifier *ban, *ban_next;
7127 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
7128 if (ban->attached_aio_context == attached_aio_context &&
7129 ban->detach_aio_context == detach_aio_context &&
7130 ban->opaque == opaque &&
7131 ban->deleted == false)
7133 if (bs->walking_aio_notifiers) {
7134 ban->deleted = true;
7135 } else {
7136 bdrv_do_remove_aio_context_notifier(ban);
7138 return;
7142 abort();
7145 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
7146 BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
7147 bool force,
7148 Error **errp)
7150 if (!bs->drv) {
7151 error_setg(errp, "Node is ejected");
7152 return -ENOMEDIUM;
7154 if (!bs->drv->bdrv_amend_options) {
7155 error_setg(errp, "Block driver '%s' does not support option amendment",
7156 bs->drv->format_name);
7157 return -ENOTSUP;
7159 return bs->drv->bdrv_amend_options(bs, opts, status_cb,
7160 cb_opaque, force, errp);
7164 * This function checks whether the given @to_replace is allowed to be
7165 * replaced by a node that always shows the same data as @bs. This is
7166 * used for example to verify whether the mirror job can replace
7167 * @to_replace by the target mirrored from @bs.
7168 * To be replaceable, @bs and @to_replace may either be guaranteed to
7169 * always show the same data (because they are only connected through
7170 * filters), or some driver may allow replacing one of its children
7171 * because it can guarantee that this child's data is not visible at
7172 * all (for example, for dissenting quorum children that have no other
7173 * parents).
7175 bool bdrv_recurse_can_replace(BlockDriverState *bs,
7176 BlockDriverState *to_replace)
7178 BlockDriverState *filtered;
7180 if (!bs || !bs->drv) {
7181 return false;
7184 if (bs == to_replace) {
7185 return true;
7188 /* See what the driver can do */
7189 if (bs->drv->bdrv_recurse_can_replace) {
7190 return bs->drv->bdrv_recurse_can_replace(bs, to_replace);
7193 /* For filters without an own implementation, we can recurse on our own */
7194 filtered = bdrv_filter_bs(bs);
7195 if (filtered) {
7196 return bdrv_recurse_can_replace(filtered, to_replace);
7199 /* Safe default */
7200 return false;
7204 * Check whether the given @node_name can be replaced by a node that
7205 * has the same data as @parent_bs. If so, return @node_name's BDS;
7206 * NULL otherwise.
7208 * @node_name must be a (recursive) *child of @parent_bs (or this
7209 * function will return NULL).
7211 * The result (whether the node can be replaced or not) is only valid
7212 * for as long as no graph or permission changes occur.
7214 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
7215 const char *node_name, Error **errp)
7217 BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
7218 AioContext *aio_context;
7220 if (!to_replace_bs) {
7221 error_setg(errp, "Failed to find node with node-name='%s'", node_name);
7222 return NULL;
7225 aio_context = bdrv_get_aio_context(to_replace_bs);
7226 aio_context_acquire(aio_context);
7228 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
7229 to_replace_bs = NULL;
7230 goto out;
7233 /* We don't want arbitrary node of the BDS chain to be replaced only the top
7234 * most non filter in order to prevent data corruption.
7235 * Another benefit is that this tests exclude backing files which are
7236 * blocked by the backing blockers.
7238 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) {
7239 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', "
7240 "because it cannot be guaranteed that doing so would not "
7241 "lead to an abrupt change of visible data",
7242 node_name, parent_bs->node_name);
7243 to_replace_bs = NULL;
7244 goto out;
7247 out:
7248 aio_context_release(aio_context);
7249 return to_replace_bs;
7253 * Iterates through the list of runtime option keys that are said to
7254 * be "strong" for a BDS. An option is called "strong" if it changes
7255 * a BDS's data. For example, the null block driver's "size" and
7256 * "read-zeroes" options are strong, but its "latency-ns" option is
7257 * not.
7259 * If a key returned by this function ends with a dot, all options
7260 * starting with that prefix are strong.
7262 static const char *const *strong_options(BlockDriverState *bs,
7263 const char *const *curopt)
7265 static const char *const global_options[] = {
7266 "driver", "filename", NULL
7269 if (!curopt) {
7270 return &global_options[0];
7273 curopt++;
7274 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
7275 curopt = bs->drv->strong_runtime_opts;
7278 return (curopt && *curopt) ? curopt : NULL;
7282 * Copies all strong runtime options from bs->options to the given
7283 * QDict. The set of strong option keys is determined by invoking
7284 * strong_options().
7286 * Returns true iff any strong option was present in bs->options (and
7287 * thus copied to the target QDict) with the exception of "filename"
7288 * and "driver". The caller is expected to use this value to decide
7289 * whether the existence of strong options prevents the generation of
7290 * a plain filename.
7292 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
7294 bool found_any = false;
7295 const char *const *option_name = NULL;
7297 if (!bs->drv) {
7298 return false;
7301 while ((option_name = strong_options(bs, option_name))) {
7302 bool option_given = false;
7304 assert(strlen(*option_name) > 0);
7305 if ((*option_name)[strlen(*option_name) - 1] != '.') {
7306 QObject *entry = qdict_get(bs->options, *option_name);
7307 if (!entry) {
7308 continue;
7311 qdict_put_obj(d, *option_name, qobject_ref(entry));
7312 option_given = true;
7313 } else {
7314 const QDictEntry *entry;
7315 for (entry = qdict_first(bs->options); entry;
7316 entry = qdict_next(bs->options, entry))
7318 if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
7319 qdict_put_obj(d, qdict_entry_key(entry),
7320 qobject_ref(qdict_entry_value(entry)));
7321 option_given = true;
7326 /* While "driver" and "filename" need to be included in a JSON filename,
7327 * their existence does not prohibit generation of a plain filename. */
7328 if (!found_any && option_given &&
7329 strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
7331 found_any = true;
7335 if (!qdict_haskey(d, "driver")) {
7336 /* Drivers created with bdrv_new_open_driver() may not have a
7337 * @driver option. Add it here. */
7338 qdict_put_str(d, "driver", bs->drv->format_name);
7341 return found_any;
7344 /* Note: This function may return false positives; it may return true
7345 * even if opening the backing file specified by bs's image header
7346 * would result in exactly bs->backing. */
7347 bool bdrv_backing_overridden(BlockDriverState *bs)
7349 if (bs->backing) {
7350 return strcmp(bs->auto_backing_file,
7351 bs->backing->bs->filename);
7352 } else {
7353 /* No backing BDS, so if the image header reports any backing
7354 * file, it must have been suppressed */
7355 return bs->auto_backing_file[0] != '\0';
7359 /* Updates the following BDS fields:
7360 * - exact_filename: A filename which may be used for opening a block device
7361 * which (mostly) equals the given BDS (even without any
7362 * other options; so reading and writing must return the same
7363 * results, but caching etc. may be different)
7364 * - full_open_options: Options which, when given when opening a block device
7365 * (without a filename), result in a BDS (mostly)
7366 * equalling the given one
7367 * - filename: If exact_filename is set, it is copied here. Otherwise,
7368 * full_open_options is converted to a JSON object, prefixed with
7369 * "json:" (for use through the JSON pseudo protocol) and put here.
7371 void bdrv_refresh_filename(BlockDriverState *bs)
7373 BlockDriver *drv = bs->drv;
7374 BdrvChild *child;
7375 BlockDriverState *primary_child_bs;
7376 QDict *opts;
7377 bool backing_overridden;
7378 bool generate_json_filename; /* Whether our default implementation should
7379 fill exact_filename (false) or not (true) */
7381 if (!drv) {
7382 return;
7385 /* This BDS's file name may depend on any of its children's file names, so
7386 * refresh those first */
7387 QLIST_FOREACH(child, &bs->children, next) {
7388 bdrv_refresh_filename(child->bs);
7391 if (bs->implicit) {
7392 /* For implicit nodes, just copy everything from the single child */
7393 child = QLIST_FIRST(&bs->children);
7394 assert(QLIST_NEXT(child, next) == NULL);
7396 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
7397 child->bs->exact_filename);
7398 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
7400 qobject_unref(bs->full_open_options);
7401 bs->full_open_options = qobject_ref(child->bs->full_open_options);
7403 return;
7406 backing_overridden = bdrv_backing_overridden(bs);
7408 if (bs->open_flags & BDRV_O_NO_IO) {
7409 /* Without I/O, the backing file does not change anything.
7410 * Therefore, in such a case (primarily qemu-img), we can
7411 * pretend the backing file has not been overridden even if
7412 * it technically has been. */
7413 backing_overridden = false;
7416 /* Gather the options QDict */
7417 opts = qdict_new();
7418 generate_json_filename = append_strong_runtime_options(opts, bs);
7419 generate_json_filename |= backing_overridden;
7421 if (drv->bdrv_gather_child_options) {
7422 /* Some block drivers may not want to present all of their children's
7423 * options, or name them differently from BdrvChild.name */
7424 drv->bdrv_gather_child_options(bs, opts, backing_overridden);
7425 } else {
7426 QLIST_FOREACH(child, &bs->children, next) {
7427 if (child == bs->backing && !backing_overridden) {
7428 /* We can skip the backing BDS if it has not been overridden */
7429 continue;
7432 qdict_put(opts, child->name,
7433 qobject_ref(child->bs->full_open_options));
7436 if (backing_overridden && !bs->backing) {
7437 /* Force no backing file */
7438 qdict_put_null(opts, "backing");
7442 qobject_unref(bs->full_open_options);
7443 bs->full_open_options = opts;
7445 primary_child_bs = bdrv_primary_bs(bs);
7447 if (drv->bdrv_refresh_filename) {
7448 /* Obsolete information is of no use here, so drop the old file name
7449 * information before refreshing it */
7450 bs->exact_filename[0] = '\0';
7452 drv->bdrv_refresh_filename(bs);
7453 } else if (primary_child_bs) {
7455 * Try to reconstruct valid information from the underlying
7456 * file -- this only works for format nodes (filter nodes
7457 * cannot be probed and as such must be selected by the user
7458 * either through an options dict, or through a special
7459 * filename which the filter driver must construct in its
7460 * .bdrv_refresh_filename() implementation).
7463 bs->exact_filename[0] = '\0';
7466 * We can use the underlying file's filename if:
7467 * - it has a filename,
7468 * - the current BDS is not a filter,
7469 * - the file is a protocol BDS, and
7470 * - opening that file (as this BDS's format) will automatically create
7471 * the BDS tree we have right now, that is:
7472 * - the user did not significantly change this BDS's behavior with
7473 * some explicit (strong) options
7474 * - no non-file child of this BDS has been overridden by the user
7475 * Both of these conditions are represented by generate_json_filename.
7477 if (primary_child_bs->exact_filename[0] &&
7478 primary_child_bs->drv->bdrv_file_open &&
7479 !drv->is_filter && !generate_json_filename)
7481 strcpy(bs->exact_filename, primary_child_bs->exact_filename);
7485 if (bs->exact_filename[0]) {
7486 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
7487 } else {
7488 GString *json = qobject_to_json(QOBJECT(bs->full_open_options));
7489 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s",
7490 json->str) >= sizeof(bs->filename)) {
7491 /* Give user a hint if we truncated things. */
7492 strcpy(bs->filename + sizeof(bs->filename) - 4, "...");
7494 g_string_free(json, true);
7498 char *bdrv_dirname(BlockDriverState *bs, Error **errp)
7500 BlockDriver *drv = bs->drv;
7501 BlockDriverState *child_bs;
7503 if (!drv) {
7504 error_setg(errp, "Node '%s' is ejected", bs->node_name);
7505 return NULL;
7508 if (drv->bdrv_dirname) {
7509 return drv->bdrv_dirname(bs, errp);
7512 child_bs = bdrv_primary_bs(bs);
7513 if (child_bs) {
7514 return bdrv_dirname(child_bs, errp);
7517 bdrv_refresh_filename(bs);
7518 if (bs->exact_filename[0] != '\0') {
7519 return path_combine(bs->exact_filename, "");
7522 error_setg(errp, "Cannot generate a base directory for %s nodes",
7523 drv->format_name);
7524 return NULL;
7528 * Hot add/remove a BDS's child. So the user can take a child offline when
7529 * it is broken and take a new child online
7531 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
7532 Error **errp)
7535 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
7536 error_setg(errp, "The node %s does not support adding a child",
7537 bdrv_get_device_or_node_name(parent_bs));
7538 return;
7541 if (!QLIST_EMPTY(&child_bs->parents)) {
7542 error_setg(errp, "The node %s already has a parent",
7543 child_bs->node_name);
7544 return;
7547 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
7550 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
7552 BdrvChild *tmp;
7554 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
7555 error_setg(errp, "The node %s does not support removing a child",
7556 bdrv_get_device_or_node_name(parent_bs));
7557 return;
7560 QLIST_FOREACH(tmp, &parent_bs->children, next) {
7561 if (tmp == child) {
7562 break;
7566 if (!tmp) {
7567 error_setg(errp, "The node %s does not have a child named %s",
7568 bdrv_get_device_or_node_name(parent_bs),
7569 bdrv_get_device_or_node_name(child->bs));
7570 return;
7573 parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
7576 int bdrv_make_empty(BdrvChild *c, Error **errp)
7578 BlockDriver *drv = c->bs->drv;
7579 int ret;
7581 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED));
7583 if (!drv->bdrv_make_empty) {
7584 error_setg(errp, "%s does not support emptying nodes",
7585 drv->format_name);
7586 return -ENOTSUP;
7589 ret = drv->bdrv_make_empty(c->bs);
7590 if (ret < 0) {
7591 error_setg_errno(errp, -ret, "Failed to empty %s",
7592 c->bs->filename);
7593 return ret;
7596 return 0;
7600 * Return the child that @bs acts as an overlay for, and from which data may be
7601 * copied in COW or COR operations. Usually this is the backing file.
7603 BdrvChild *bdrv_cow_child(BlockDriverState *bs)
7605 if (!bs || !bs->drv) {
7606 return NULL;
7609 if (bs->drv->is_filter) {
7610 return NULL;
7613 if (!bs->backing) {
7614 return NULL;
7617 assert(bs->backing->role & BDRV_CHILD_COW);
7618 return bs->backing;
7622 * If @bs acts as a filter for exactly one of its children, return
7623 * that child.
7625 BdrvChild *bdrv_filter_child(BlockDriverState *bs)
7627 BdrvChild *c;
7629 if (!bs || !bs->drv) {
7630 return NULL;
7633 if (!bs->drv->is_filter) {
7634 return NULL;
7637 /* Only one of @backing or @file may be used */
7638 assert(!(bs->backing && bs->file));
7640 c = bs->backing ?: bs->file;
7641 if (!c) {
7642 return NULL;
7645 assert(c->role & BDRV_CHILD_FILTERED);
7646 return c;
7650 * Return either the result of bdrv_cow_child() or bdrv_filter_child(),
7651 * whichever is non-NULL.
7653 * Return NULL if both are NULL.
7655 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs)
7657 BdrvChild *cow_child = bdrv_cow_child(bs);
7658 BdrvChild *filter_child = bdrv_filter_child(bs);
7660 /* Filter nodes cannot have COW backing files */
7661 assert(!(cow_child && filter_child));
7663 return cow_child ?: filter_child;
7667 * Return the primary child of this node: For filters, that is the
7668 * filtered child. For other nodes, that is usually the child storing
7669 * metadata.
7670 * (A generally more helpful description is that this is (usually) the
7671 * child that has the same filename as @bs.)
7673 * Drivers do not necessarily have a primary child; for example quorum
7674 * does not.
7676 BdrvChild *bdrv_primary_child(BlockDriverState *bs)
7678 BdrvChild *c, *found = NULL;
7680 QLIST_FOREACH(c, &bs->children, next) {
7681 if (c->role & BDRV_CHILD_PRIMARY) {
7682 assert(!found);
7683 found = c;
7687 return found;
7690 static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs,
7691 bool stop_on_explicit_filter)
7693 BdrvChild *c;
7695 if (!bs) {
7696 return NULL;
7699 while (!(stop_on_explicit_filter && !bs->implicit)) {
7700 c = bdrv_filter_child(bs);
7701 if (!c) {
7703 * A filter that is embedded in a working block graph must
7704 * have a child. Assert this here so this function does
7705 * not return a filter node that is not expected by the
7706 * caller.
7708 assert(!bs->drv || !bs->drv->is_filter);
7709 break;
7711 bs = c->bs;
7714 * Note that this treats nodes with bs->drv == NULL as not being
7715 * filters (bs->drv == NULL should be replaced by something else
7716 * anyway).
7717 * The advantage of this behavior is that this function will thus
7718 * always return a non-NULL value (given a non-NULL @bs).
7721 return bs;
7725 * Return the first BDS that has not been added implicitly or that
7726 * does not have a filtered child down the chain starting from @bs
7727 * (including @bs itself).
7729 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
7731 return bdrv_do_skip_filters(bs, true);
7735 * Return the first BDS that does not have a filtered child down the
7736 * chain starting from @bs (including @bs itself).
7738 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
7740 return bdrv_do_skip_filters(bs, false);
7744 * For a backing chain, return the first non-filter backing image of
7745 * the first non-filter image.
7747 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
7749 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));
7753 * Check whether [offset, offset + bytes) overlaps with the cached
7754 * block-status data region.
7756 * If so, and @pnum is not NULL, set *pnum to `bsc.data_end - offset`,
7757 * which is what bdrv_bsc_is_data()'s interface needs.
7758 * Otherwise, *pnum is not touched.
7760 static bool bdrv_bsc_range_overlaps_locked(BlockDriverState *bs,
7761 int64_t offset, int64_t bytes,
7762 int64_t *pnum)
7764 BdrvBlockStatusCache *bsc = qatomic_rcu_read(&bs->block_status_cache);
7765 bool overlaps;
7767 overlaps =
7768 qatomic_read(&bsc->valid) &&
7769 ranges_overlap(offset, bytes, bsc->data_start,
7770 bsc->data_end - bsc->data_start);
7772 if (overlaps && pnum) {
7773 *pnum = bsc->data_end - offset;
7776 return overlaps;
7780 * See block_int.h for this function's documentation.
7782 bool bdrv_bsc_is_data(BlockDriverState *bs, int64_t offset, int64_t *pnum)
7784 RCU_READ_LOCK_GUARD();
7786 return bdrv_bsc_range_overlaps_locked(bs, offset, 1, pnum);
7790 * See block_int.h for this function's documentation.
7792 void bdrv_bsc_invalidate_range(BlockDriverState *bs,
7793 int64_t offset, int64_t bytes)
7795 RCU_READ_LOCK_GUARD();
7797 if (bdrv_bsc_range_overlaps_locked(bs, offset, bytes, NULL)) {
7798 qatomic_set(&bs->block_status_cache->valid, false);
7803 * See block_int.h for this function's documentation.
7805 void bdrv_bsc_fill(BlockDriverState *bs, int64_t offset, int64_t bytes)
7807 BdrvBlockStatusCache *new_bsc = g_new(BdrvBlockStatusCache, 1);
7808 BdrvBlockStatusCache *old_bsc;
7810 *new_bsc = (BdrvBlockStatusCache) {
7811 .valid = true,
7812 .data_start = offset,
7813 .data_end = offset + bytes,
7816 QEMU_LOCK_GUARD(&bs->bsc_modify_lock);
7818 old_bsc = qatomic_rcu_read(&bs->block_status_cache);
7819 qatomic_rcu_set(&bs->block_status_cache, new_bsc);
7820 if (old_bsc) {
7821 g_free_rcu(old_bsc, rcu);