block: Mark bdrv_first_blk() and bdrv_is_root_node() GRAPH_RDLOCK
[qemu/kevin.git] / block.c
blob701f77fe2f2663f3e71e23fefea943eb99f5865e
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/dirty-bitmap.h"
31 #include "block/fuse.h"
32 #include "block/nbd.h"
33 #include "block/qdict.h"
34 #include "qemu/error-report.h"
35 #include "block/module_block.h"
36 #include "qemu/main-loop.h"
37 #include "qemu/module.h"
38 #include "qapi/error.h"
39 #include "qapi/qmp/qdict.h"
40 #include "qapi/qmp/qjson.h"
41 #include "qapi/qmp/qnull.h"
42 #include "qapi/qmp/qstring.h"
43 #include "qapi/qobject-output-visitor.h"
44 #include "qapi/qapi-visit-block-core.h"
45 #include "sysemu/block-backend.h"
46 #include "qemu/notify.h"
47 #include "qemu/option.h"
48 #include "qemu/coroutine.h"
49 #include "block/qapi.h"
50 #include "qemu/timer.h"
51 #include "qemu/cutils.h"
52 #include "qemu/id.h"
53 #include "qemu/range.h"
54 #include "qemu/rcu.h"
55 #include "block/coroutines.h"
57 #ifdef CONFIG_BSD
58 #include <sys/ioctl.h>
59 #include <sys/queue.h>
60 #if defined(HAVE_SYS_DISK_H)
61 #include <sys/disk.h>
62 #endif
63 #endif
65 #ifdef _WIN32
66 #include <windows.h>
67 #endif
69 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
71 /* Protected by BQL */
72 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
73 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
75 /* Protected by BQL */
76 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
77 QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
79 /* Protected by BQL */
80 static QLIST_HEAD(, BlockDriver) bdrv_drivers =
81 QLIST_HEAD_INITIALIZER(bdrv_drivers);
83 static BlockDriverState *bdrv_open_inherit(const char *filename,
84 const char *reference,
85 QDict *options, int flags,
86 BlockDriverState *parent,
87 const BdrvChildClass *child_class,
88 BdrvChildRole child_role,
89 Error **errp);
91 static bool bdrv_recurse_has_child(BlockDriverState *bs,
92 BlockDriverState *child);
94 static void GRAPH_WRLOCK
95 bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs);
97 static void GRAPH_WRLOCK
98 bdrv_remove_child(BdrvChild *child, Transaction *tran);
100 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
101 BlockReopenQueue *queue,
102 Transaction *change_child_tran, Error **errp);
103 static void bdrv_reopen_commit(BDRVReopenState *reopen_state);
104 static void bdrv_reopen_abort(BDRVReopenState *reopen_state);
106 static bool bdrv_backing_overridden(BlockDriverState *bs);
108 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
109 GHashTable *visited, Transaction *tran,
110 Error **errp);
112 /* If non-zero, use only whitelisted block drivers */
113 static int use_bdrv_whitelist;
115 #ifdef _WIN32
116 static int is_windows_drive_prefix(const char *filename)
118 return (((filename[0] >= 'a' && filename[0] <= 'z') ||
119 (filename[0] >= 'A' && filename[0] <= 'Z')) &&
120 filename[1] == ':');
123 int is_windows_drive(const char *filename)
125 if (is_windows_drive_prefix(filename) &&
126 filename[2] == '\0')
127 return 1;
128 if (strstart(filename, "\\\\.\\", NULL) ||
129 strstart(filename, "//./", NULL))
130 return 1;
131 return 0;
133 #endif
135 size_t bdrv_opt_mem_align(BlockDriverState *bs)
137 if (!bs || !bs->drv) {
138 /* page size or 4k (hdd sector size) should be on the safe side */
139 return MAX(4096, qemu_real_host_page_size());
141 IO_CODE();
143 return bs->bl.opt_mem_alignment;
146 size_t bdrv_min_mem_align(BlockDriverState *bs)
148 if (!bs || !bs->drv) {
149 /* page size or 4k (hdd sector size) should be on the safe side */
150 return MAX(4096, qemu_real_host_page_size());
152 IO_CODE();
154 return bs->bl.min_mem_alignment;
157 /* check if the path starts with "<protocol>:" */
158 int path_has_protocol(const char *path)
160 const char *p;
162 #ifdef _WIN32
163 if (is_windows_drive(path) ||
164 is_windows_drive_prefix(path)) {
165 return 0;
167 p = path + strcspn(path, ":/\\");
168 #else
169 p = path + strcspn(path, ":/");
170 #endif
172 return *p == ':';
175 int path_is_absolute(const char *path)
177 #ifdef _WIN32
178 /* specific case for names like: "\\.\d:" */
179 if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
180 return 1;
182 return (*path == '/' || *path == '\\');
183 #else
184 return (*path == '/');
185 #endif
188 /* if filename is absolute, just return its duplicate. Otherwise, build a
189 path to it by considering it is relative to base_path. URL are
190 supported. */
191 char *path_combine(const char *base_path, const char *filename)
193 const char *protocol_stripped = NULL;
194 const char *p, *p1;
195 char *result;
196 int len;
198 if (path_is_absolute(filename)) {
199 return g_strdup(filename);
202 if (path_has_protocol(base_path)) {
203 protocol_stripped = strchr(base_path, ':');
204 if (protocol_stripped) {
205 protocol_stripped++;
208 p = protocol_stripped ?: base_path;
210 p1 = strrchr(base_path, '/');
211 #ifdef _WIN32
213 const char *p2;
214 p2 = strrchr(base_path, '\\');
215 if (!p1 || p2 > p1) {
216 p1 = p2;
219 #endif
220 if (p1) {
221 p1++;
222 } else {
223 p1 = base_path;
225 if (p1 > p) {
226 p = p1;
228 len = p - base_path;
230 result = g_malloc(len + strlen(filename) + 1);
231 memcpy(result, base_path, len);
232 strcpy(result + len, filename);
234 return result;
238 * Helper function for bdrv_parse_filename() implementations to remove optional
239 * protocol prefixes (especially "file:") from a filename and for putting the
240 * stripped filename into the options QDict if there is such a prefix.
242 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
243 QDict *options)
245 if (strstart(filename, prefix, &filename)) {
246 /* Stripping the explicit protocol prefix may result in a protocol
247 * prefix being (wrongly) detected (if the filename contains a colon) */
248 if (path_has_protocol(filename)) {
249 GString *fat_filename;
251 /* This means there is some colon before the first slash; therefore,
252 * this cannot be an absolute path */
253 assert(!path_is_absolute(filename));
255 /* And we can thus fix the protocol detection issue by prefixing it
256 * by "./" */
257 fat_filename = g_string_new("./");
258 g_string_append(fat_filename, filename);
260 assert(!path_has_protocol(fat_filename->str));
262 qdict_put(options, "filename",
263 qstring_from_gstring(fat_filename));
264 } else {
265 /* If no protocol prefix was detected, we can use the shortened
266 * filename as-is */
267 qdict_put_str(options, "filename", filename);
273 /* Returns whether the image file is opened as read-only. Note that this can
274 * return false and writing to the image file is still not possible because the
275 * image is inactivated. */
276 bool bdrv_is_read_only(BlockDriverState *bs)
278 IO_CODE();
279 return !(bs->open_flags & BDRV_O_RDWR);
282 static int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
283 bool ignore_allow_rdw, Error **errp)
285 IO_CODE();
287 /* Do not set read_only if copy_on_read is enabled */
288 if (bs->copy_on_read && read_only) {
289 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
290 bdrv_get_device_or_node_name(bs));
291 return -EINVAL;
294 /* Do not clear read_only if it is prohibited */
295 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
296 !ignore_allow_rdw)
298 error_setg(errp, "Node '%s' is read only",
299 bdrv_get_device_or_node_name(bs));
300 return -EPERM;
303 return 0;
307 * Called by a driver that can only provide a read-only image.
309 * Returns 0 if the node is already read-only or it could switch the node to
310 * read-only because BDRV_O_AUTO_RDONLY is set.
312 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
313 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
314 * is not NULL, it is used as the error message for the Error object.
316 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
317 Error **errp)
319 int ret = 0;
320 IO_CODE();
322 if (!(bs->open_flags & BDRV_O_RDWR)) {
323 return 0;
325 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
326 goto fail;
329 ret = bdrv_can_set_read_only(bs, true, false, NULL);
330 if (ret < 0) {
331 goto fail;
334 bs->open_flags &= ~BDRV_O_RDWR;
336 return 0;
338 fail:
339 error_setg(errp, "%s", errmsg ?: "Image is read-only");
340 return -EACCES;
344 * If @backing is empty, this function returns NULL without setting
345 * @errp. In all other cases, NULL will only be returned with @errp
346 * set.
348 * Therefore, a return value of NULL without @errp set means that
349 * there is no backing file; if @errp is set, there is one but its
350 * absolute filename cannot be generated.
352 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
353 const char *backing,
354 Error **errp)
356 if (backing[0] == '\0') {
357 return NULL;
358 } else if (path_has_protocol(backing) || path_is_absolute(backing)) {
359 return g_strdup(backing);
360 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
361 error_setg(errp, "Cannot use relative backing file names for '%s'",
362 backed);
363 return NULL;
364 } else {
365 return path_combine(backed, backing);
370 * If @filename is empty or NULL, this function returns NULL without
371 * setting @errp. In all other cases, NULL will only be returned with
372 * @errp set.
374 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
375 const char *filename, Error **errp)
377 char *dir, *full_name;
379 if (!filename || filename[0] == '\0') {
380 return NULL;
381 } else if (path_has_protocol(filename) || path_is_absolute(filename)) {
382 return g_strdup(filename);
385 dir = bdrv_dirname(relative_to, errp);
386 if (!dir) {
387 return NULL;
390 full_name = g_strconcat(dir, filename, NULL);
391 g_free(dir);
392 return full_name;
395 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
397 GLOBAL_STATE_CODE();
398 return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
401 void bdrv_register(BlockDriver *bdrv)
403 assert(bdrv->format_name);
404 GLOBAL_STATE_CODE();
405 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
408 BlockDriverState *bdrv_new(void)
410 BlockDriverState *bs;
411 int i;
413 GLOBAL_STATE_CODE();
415 bs = g_new0(BlockDriverState, 1);
416 QLIST_INIT(&bs->dirty_bitmaps);
417 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
418 QLIST_INIT(&bs->op_blockers[i]);
420 qemu_mutex_init(&bs->reqs_lock);
421 qemu_mutex_init(&bs->dirty_bitmap_mutex);
422 bs->refcnt = 1;
423 bs->aio_context = qemu_get_aio_context();
425 qemu_co_queue_init(&bs->flush_queue);
427 qemu_co_mutex_init(&bs->bsc_modify_lock);
428 bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1);
430 for (i = 0; i < bdrv_drain_all_count; i++) {
431 bdrv_drained_begin(bs);
434 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
436 return bs;
439 static BlockDriver *bdrv_do_find_format(const char *format_name)
441 BlockDriver *drv1;
442 GLOBAL_STATE_CODE();
444 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
445 if (!strcmp(drv1->format_name, format_name)) {
446 return drv1;
450 return NULL;
453 BlockDriver *bdrv_find_format(const char *format_name)
455 BlockDriver *drv1;
456 int i;
458 GLOBAL_STATE_CODE();
460 drv1 = bdrv_do_find_format(format_name);
461 if (drv1) {
462 return drv1;
465 /* The driver isn't registered, maybe we need to load a module */
466 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
467 if (!strcmp(block_driver_modules[i].format_name, format_name)) {
468 Error *local_err = NULL;
469 int rv = block_module_load(block_driver_modules[i].library_name,
470 &local_err);
471 if (rv > 0) {
472 return bdrv_do_find_format(format_name);
473 } else if (rv < 0) {
474 error_report_err(local_err);
476 break;
479 return NULL;
482 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
484 static const char *whitelist_rw[] = {
485 CONFIG_BDRV_RW_WHITELIST
486 NULL
488 static const char *whitelist_ro[] = {
489 CONFIG_BDRV_RO_WHITELIST
490 NULL
492 const char **p;
494 if (!whitelist_rw[0] && !whitelist_ro[0]) {
495 return 1; /* no whitelist, anything goes */
498 for (p = whitelist_rw; *p; p++) {
499 if (!strcmp(format_name, *p)) {
500 return 1;
503 if (read_only) {
504 for (p = whitelist_ro; *p; p++) {
505 if (!strcmp(format_name, *p)) {
506 return 1;
510 return 0;
513 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
515 GLOBAL_STATE_CODE();
516 return bdrv_format_is_whitelisted(drv->format_name, read_only);
519 bool bdrv_uses_whitelist(void)
521 return use_bdrv_whitelist;
524 typedef struct CreateCo {
525 BlockDriver *drv;
526 char *filename;
527 QemuOpts *opts;
528 int ret;
529 Error *err;
530 } CreateCo;
532 int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename,
533 QemuOpts *opts, Error **errp)
535 int ret;
536 GLOBAL_STATE_CODE();
537 ERRP_GUARD();
539 if (!drv->bdrv_co_create_opts) {
540 error_setg(errp, "Driver '%s' does not support image creation",
541 drv->format_name);
542 return -ENOTSUP;
545 ret = drv->bdrv_co_create_opts(drv, filename, opts, errp);
546 if (ret < 0 && !*errp) {
547 error_setg_errno(errp, -ret, "Could not create image");
550 return ret;
554 * Helper function for bdrv_create_file_fallback(): Resize @blk to at
555 * least the given @minimum_size.
557 * On success, return @blk's actual length.
558 * Otherwise, return -errno.
560 static int64_t coroutine_fn GRAPH_UNLOCKED
561 create_file_fallback_truncate(BlockBackend *blk, int64_t minimum_size,
562 Error **errp)
564 Error *local_err = NULL;
565 int64_t size;
566 int ret;
568 GLOBAL_STATE_CODE();
570 ret = blk_co_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0,
571 &local_err);
572 if (ret < 0 && ret != -ENOTSUP) {
573 error_propagate(errp, local_err);
574 return ret;
577 size = blk_co_getlength(blk);
578 if (size < 0) {
579 error_free(local_err);
580 error_setg_errno(errp, -size,
581 "Failed to inquire the new image file's length");
582 return size;
585 if (size < minimum_size) {
586 /* Need to grow the image, but we failed to do that */
587 error_propagate(errp, local_err);
588 return -ENOTSUP;
591 error_free(local_err);
592 local_err = NULL;
594 return size;
598 * Helper function for bdrv_create_file_fallback(): Zero the first
599 * sector to remove any potentially pre-existing image header.
601 static int coroutine_fn
602 create_file_fallback_zero_first_sector(BlockBackend *blk,
603 int64_t current_size,
604 Error **errp)
606 int64_t bytes_to_clear;
607 int ret;
609 GLOBAL_STATE_CODE();
611 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
612 if (bytes_to_clear) {
613 ret = blk_co_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
614 if (ret < 0) {
615 error_setg_errno(errp, -ret,
616 "Failed to clear the new image's first sector");
617 return ret;
621 return 0;
625 * Simple implementation of bdrv_co_create_opts for protocol drivers
626 * which only support creation via opening a file
627 * (usually existing raw storage device)
629 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
630 const char *filename,
631 QemuOpts *opts,
632 Error **errp)
634 BlockBackend *blk;
635 QDict *options;
636 int64_t size = 0;
637 char *buf = NULL;
638 PreallocMode prealloc;
639 Error *local_err = NULL;
640 int ret;
642 GLOBAL_STATE_CODE();
644 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
645 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
646 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
647 PREALLOC_MODE_OFF, &local_err);
648 g_free(buf);
649 if (local_err) {
650 error_propagate(errp, local_err);
651 return -EINVAL;
654 if (prealloc != PREALLOC_MODE_OFF) {
655 error_setg(errp, "Unsupported preallocation mode '%s'",
656 PreallocMode_str(prealloc));
657 return -ENOTSUP;
660 options = qdict_new();
661 qdict_put_str(options, "driver", drv->format_name);
663 blk = blk_co_new_open(filename, NULL, options,
664 BDRV_O_RDWR | BDRV_O_RESIZE, errp);
665 if (!blk) {
666 error_prepend(errp, "Protocol driver '%s' does not support creating "
667 "new images, so an existing image must be selected as "
668 "the target; however, opening the given target as an "
669 "existing image failed: ",
670 drv->format_name);
671 return -EINVAL;
674 size = create_file_fallback_truncate(blk, size, errp);
675 if (size < 0) {
676 ret = size;
677 goto out;
680 ret = create_file_fallback_zero_first_sector(blk, size, errp);
681 if (ret < 0) {
682 goto out;
685 ret = 0;
686 out:
687 blk_co_unref(blk);
688 return ret;
691 int coroutine_fn bdrv_co_create_file(const char *filename, QemuOpts *opts,
692 Error **errp)
694 QemuOpts *protocol_opts;
695 BlockDriver *drv;
696 QDict *qdict;
697 int ret;
699 GLOBAL_STATE_CODE();
701 drv = bdrv_find_protocol(filename, true, errp);
702 if (drv == NULL) {
703 return -ENOENT;
706 if (!drv->create_opts) {
707 error_setg(errp, "Driver '%s' does not support image creation",
708 drv->format_name);
709 return -ENOTSUP;
713 * 'opts' contains a QemuOptsList with a combination of format and protocol
714 * default values.
716 * The format properly removes its options, but the default values remain
717 * in 'opts->list'. So if the protocol has options with the same name
718 * (e.g. rbd has 'cluster_size' as qcow2), it will see the default values
719 * of the format, since for overlapping options, the format wins.
721 * To avoid this issue, lets convert QemuOpts to QDict, in this way we take
722 * only the set options, and then convert it back to QemuOpts, using the
723 * create_opts of the protocol. So the new QemuOpts, will contain only the
724 * protocol defaults.
726 qdict = qemu_opts_to_qdict(opts, NULL);
727 protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp);
728 if (protocol_opts == NULL) {
729 ret = -EINVAL;
730 goto out;
733 ret = bdrv_co_create(drv, filename, protocol_opts, errp);
734 out:
735 qemu_opts_del(protocol_opts);
736 qobject_unref(qdict);
737 return ret;
740 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
742 Error *local_err = NULL;
743 int ret;
745 IO_CODE();
746 assert(bs != NULL);
747 assert_bdrv_graph_readable();
749 if (!bs->drv) {
750 error_setg(errp, "Block node '%s' is not opened", bs->filename);
751 return -ENOMEDIUM;
754 if (!bs->drv->bdrv_co_delete_file) {
755 error_setg(errp, "Driver '%s' does not support image deletion",
756 bs->drv->format_name);
757 return -ENOTSUP;
760 ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
761 if (ret < 0) {
762 error_propagate(errp, local_err);
765 return ret;
768 void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs)
770 Error *local_err = NULL;
771 int ret;
772 IO_CODE();
774 if (!bs) {
775 return;
778 ret = bdrv_co_delete_file(bs, &local_err);
780 * ENOTSUP will happen if the block driver doesn't support
781 * the 'bdrv_co_delete_file' interface. This is a predictable
782 * scenario and shouldn't be reported back to the user.
784 if (ret == -ENOTSUP) {
785 error_free(local_err);
786 } else if (ret < 0) {
787 error_report_err(local_err);
792 * Try to get @bs's logical and physical block size.
793 * On success, store them in @bsz struct and return 0.
794 * On failure return -errno.
795 * @bs must not be empty.
797 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
799 BlockDriver *drv = bs->drv;
800 BlockDriverState *filtered = bdrv_filter_bs(bs);
801 GLOBAL_STATE_CODE();
803 if (drv && drv->bdrv_probe_blocksizes) {
804 return drv->bdrv_probe_blocksizes(bs, bsz);
805 } else if (filtered) {
806 return bdrv_probe_blocksizes(filtered, bsz);
809 return -ENOTSUP;
813 * Try to get @bs's geometry (cyls, heads, sectors).
814 * On success, store them in @geo struct and return 0.
815 * On failure return -errno.
816 * @bs must not be empty.
818 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
820 BlockDriver *drv = bs->drv;
821 BlockDriverState *filtered = bdrv_filter_bs(bs);
822 GLOBAL_STATE_CODE();
824 if (drv && drv->bdrv_probe_geometry) {
825 return drv->bdrv_probe_geometry(bs, geo);
826 } else if (filtered) {
827 return bdrv_probe_geometry(filtered, geo);
830 return -ENOTSUP;
834 * Create a uniquely-named empty temporary file.
835 * Return the actual file name used upon success, otherwise NULL.
836 * This string should be freed with g_free() when not needed any longer.
838 * Note: creating a temporary file for the caller to (re)open is
839 * inherently racy. Use g_file_open_tmp() instead whenever practical.
841 char *create_tmp_file(Error **errp)
843 int fd;
844 const char *tmpdir;
845 g_autofree char *filename = NULL;
847 tmpdir = g_get_tmp_dir();
848 #ifndef _WIN32
850 * See commit 69bef79 ("block: use /var/tmp instead of /tmp for -snapshot")
852 * This function is used to create temporary disk images (like -snapshot),
853 * so the files can become very large. /tmp is often a tmpfs where as
854 * /var/tmp is usually on a disk, so more appropriate for disk images.
856 if (!g_strcmp0(tmpdir, "/tmp")) {
857 tmpdir = "/var/tmp";
859 #endif
861 filename = g_strdup_printf("%s/vl.XXXXXX", tmpdir);
862 fd = g_mkstemp(filename);
863 if (fd < 0) {
864 error_setg_errno(errp, errno, "Could not open temporary file '%s'",
865 filename);
866 return NULL;
868 close(fd);
870 return g_steal_pointer(&filename);
874 * Detect host devices. By convention, /dev/cdrom[N] is always
875 * recognized as a host CDROM.
877 static BlockDriver *find_hdev_driver(const char *filename)
879 int score_max = 0, score;
880 BlockDriver *drv = NULL, *d;
881 GLOBAL_STATE_CODE();
883 QLIST_FOREACH(d, &bdrv_drivers, list) {
884 if (d->bdrv_probe_device) {
885 score = d->bdrv_probe_device(filename);
886 if (score > score_max) {
887 score_max = score;
888 drv = d;
893 return drv;
896 static BlockDriver *bdrv_do_find_protocol(const char *protocol)
898 BlockDriver *drv1;
899 GLOBAL_STATE_CODE();
901 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
902 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
903 return drv1;
907 return NULL;
910 BlockDriver *bdrv_find_protocol(const char *filename,
911 bool allow_protocol_prefix,
912 Error **errp)
914 BlockDriver *drv1;
915 char protocol[128];
916 int len;
917 const char *p;
918 int i;
920 GLOBAL_STATE_CODE();
921 /* TODO Drivers without bdrv_file_open must be specified explicitly */
924 * XXX(hch): we really should not let host device detection
925 * override an explicit protocol specification, but moving this
926 * later breaks access to device names with colons in them.
927 * Thanks to the brain-dead persistent naming schemes on udev-
928 * based Linux systems those actually are quite common.
930 drv1 = find_hdev_driver(filename);
931 if (drv1) {
932 return drv1;
935 if (!path_has_protocol(filename) || !allow_protocol_prefix) {
936 return &bdrv_file;
939 p = strchr(filename, ':');
940 assert(p != NULL);
941 len = p - filename;
942 if (len > sizeof(protocol) - 1)
943 len = sizeof(protocol) - 1;
944 memcpy(protocol, filename, len);
945 protocol[len] = '\0';
947 drv1 = bdrv_do_find_protocol(protocol);
948 if (drv1) {
949 return drv1;
952 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
953 if (block_driver_modules[i].protocol_name &&
954 !strcmp(block_driver_modules[i].protocol_name, protocol)) {
955 int rv = block_module_load(block_driver_modules[i].library_name, errp);
956 if (rv > 0) {
957 drv1 = bdrv_do_find_protocol(protocol);
958 } else if (rv < 0) {
959 return NULL;
961 break;
965 if (!drv1) {
966 error_setg(errp, "Unknown protocol '%s'", protocol);
968 return drv1;
972 * Guess image format by probing its contents.
973 * This is not a good idea when your image is raw (CVE-2008-2004), but
974 * we do it anyway for backward compatibility.
976 * @buf contains the image's first @buf_size bytes.
977 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
978 * but can be smaller if the image file is smaller)
979 * @filename is its filename.
981 * For all block drivers, call the bdrv_probe() method to get its
982 * probing score.
983 * Return the first block driver with the highest probing score.
985 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
986 const char *filename)
988 int score_max = 0, score;
989 BlockDriver *drv = NULL, *d;
990 IO_CODE();
992 QLIST_FOREACH(d, &bdrv_drivers, list) {
993 if (d->bdrv_probe) {
994 score = d->bdrv_probe(buf, buf_size, filename);
995 if (score > score_max) {
996 score_max = score;
997 drv = d;
1002 return drv;
1005 static int find_image_format(BlockBackend *file, const char *filename,
1006 BlockDriver **pdrv, Error **errp)
1008 BlockDriver *drv;
1009 uint8_t buf[BLOCK_PROBE_BUF_SIZE];
1010 int ret = 0;
1012 GLOBAL_STATE_CODE();
1014 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */
1015 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
1016 *pdrv = &bdrv_raw;
1017 return ret;
1020 ret = blk_pread(file, 0, sizeof(buf), buf, 0);
1021 if (ret < 0) {
1022 error_setg_errno(errp, -ret, "Could not read image for determining its "
1023 "format");
1024 *pdrv = NULL;
1025 return ret;
1028 drv = bdrv_probe_all(buf, sizeof(buf), filename);
1029 if (!drv) {
1030 error_setg(errp, "Could not determine image format: No compatible "
1031 "driver found");
1032 *pdrv = NULL;
1033 return -ENOENT;
1036 *pdrv = drv;
1037 return 0;
1041 * Set the current 'total_sectors' value
1042 * Return 0 on success, -errno on error.
1044 int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs,
1045 int64_t hint)
1047 BlockDriver *drv = bs->drv;
1048 IO_CODE();
1049 assert_bdrv_graph_readable();
1051 if (!drv) {
1052 return -ENOMEDIUM;
1055 /* Do not attempt drv->bdrv_co_getlength() on scsi-generic devices */
1056 if (bdrv_is_sg(bs))
1057 return 0;
1059 /* query actual device if possible, otherwise just trust the hint */
1060 if (drv->bdrv_co_getlength) {
1061 int64_t length = drv->bdrv_co_getlength(bs);
1062 if (length < 0) {
1063 return length;
1065 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
1068 bs->total_sectors = hint;
1070 if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) {
1071 return -EFBIG;
1074 return 0;
1078 * Combines a QDict of new block driver @options with any missing options taken
1079 * from @old_options, so that leaving out an option defaults to its old value.
1081 static void bdrv_join_options(BlockDriverState *bs, QDict *options,
1082 QDict *old_options)
1084 GLOBAL_STATE_CODE();
1085 if (bs->drv && bs->drv->bdrv_join_options) {
1086 bs->drv->bdrv_join_options(options, old_options);
1087 } else {
1088 qdict_join(options, old_options, false);
1092 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
1093 int open_flags,
1094 Error **errp)
1096 Error *local_err = NULL;
1097 char *value = qemu_opt_get_del(opts, "detect-zeroes");
1098 BlockdevDetectZeroesOptions detect_zeroes =
1099 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
1100 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
1101 GLOBAL_STATE_CODE();
1102 g_free(value);
1103 if (local_err) {
1104 error_propagate(errp, local_err);
1105 return detect_zeroes;
1108 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
1109 !(open_flags & BDRV_O_UNMAP))
1111 error_setg(errp, "setting detect-zeroes to unmap is not allowed "
1112 "without setting discard operation to unmap");
1115 return detect_zeroes;
1119 * Set open flags for aio engine
1121 * Return 0 on success, -1 if the engine specified is invalid
1123 int bdrv_parse_aio(const char *mode, int *flags)
1125 if (!strcmp(mode, "threads")) {
1126 /* do nothing, default */
1127 } else if (!strcmp(mode, "native")) {
1128 *flags |= BDRV_O_NATIVE_AIO;
1129 #ifdef CONFIG_LINUX_IO_URING
1130 } else if (!strcmp(mode, "io_uring")) {
1131 *flags |= BDRV_O_IO_URING;
1132 #endif
1133 } else {
1134 return -1;
1137 return 0;
1141 * Set open flags for a given discard mode
1143 * Return 0 on success, -1 if the discard mode was invalid.
1145 int bdrv_parse_discard_flags(const char *mode, int *flags)
1147 *flags &= ~BDRV_O_UNMAP;
1149 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
1150 /* do nothing */
1151 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
1152 *flags |= BDRV_O_UNMAP;
1153 } else {
1154 return -1;
1157 return 0;
1161 * Set open flags for a given cache mode
1163 * Return 0 on success, -1 if the cache mode was invalid.
1165 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
1167 *flags &= ~BDRV_O_CACHE_MASK;
1169 if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
1170 *writethrough = false;
1171 *flags |= BDRV_O_NOCACHE;
1172 } else if (!strcmp(mode, "directsync")) {
1173 *writethrough = true;
1174 *flags |= BDRV_O_NOCACHE;
1175 } else if (!strcmp(mode, "writeback")) {
1176 *writethrough = false;
1177 } else if (!strcmp(mode, "unsafe")) {
1178 *writethrough = false;
1179 *flags |= BDRV_O_NO_FLUSH;
1180 } else if (!strcmp(mode, "writethrough")) {
1181 *writethrough = true;
1182 } else {
1183 return -1;
1186 return 0;
1189 static char *bdrv_child_get_parent_desc(BdrvChild *c)
1191 BlockDriverState *parent = c->opaque;
1192 return g_strdup_printf("node '%s'", bdrv_get_node_name(parent));
1195 static void bdrv_child_cb_drained_begin(BdrvChild *child)
1197 BlockDriverState *bs = child->opaque;
1198 bdrv_do_drained_begin_quiesce(bs, NULL);
1201 static bool bdrv_child_cb_drained_poll(BdrvChild *child)
1203 BlockDriverState *bs = child->opaque;
1204 return bdrv_drain_poll(bs, NULL, false);
1207 static void bdrv_child_cb_drained_end(BdrvChild *child)
1209 BlockDriverState *bs = child->opaque;
1210 bdrv_drained_end(bs);
1213 static int bdrv_child_cb_inactivate(BdrvChild *child)
1215 BlockDriverState *bs = child->opaque;
1216 GLOBAL_STATE_CODE();
1217 assert(bs->open_flags & BDRV_O_INACTIVE);
1218 return 0;
1221 static bool bdrv_child_cb_change_aio_ctx(BdrvChild *child, AioContext *ctx,
1222 GHashTable *visited, Transaction *tran,
1223 Error **errp)
1225 BlockDriverState *bs = child->opaque;
1226 return bdrv_change_aio_context(bs, ctx, visited, tran, errp);
1230 * Returns the options and flags that a temporary snapshot should get, based on
1231 * the originally requested flags (the originally requested image will have
1232 * flags like a backing file)
1234 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
1235 int parent_flags, QDict *parent_options)
1237 GLOBAL_STATE_CODE();
1238 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
1240 /* For temporary files, unconditional cache=unsafe is fine */
1241 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
1242 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
1244 /* Copy the read-only and discard options from the parent */
1245 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1246 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
1248 /* aio=native doesn't work for cache.direct=off, so disable it for the
1249 * temporary snapshot */
1250 *child_flags &= ~BDRV_O_NATIVE_AIO;
1253 static void bdrv_backing_attach(BdrvChild *c)
1255 BlockDriverState *parent = c->opaque;
1256 BlockDriverState *backing_hd = c->bs;
1258 GLOBAL_STATE_CODE();
1259 assert(!parent->backing_blocker);
1260 error_setg(&parent->backing_blocker,
1261 "node is used as backing hd of '%s'",
1262 bdrv_get_device_or_node_name(parent));
1264 bdrv_refresh_filename(backing_hd);
1266 parent->open_flags &= ~BDRV_O_NO_BACKING;
1268 bdrv_op_block_all(backing_hd, parent->backing_blocker);
1269 /* Otherwise we won't be able to commit or stream */
1270 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
1271 parent->backing_blocker);
1272 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
1273 parent->backing_blocker);
1275 * We do backup in 3 ways:
1276 * 1. drive backup
1277 * The target bs is new opened, and the source is top BDS
1278 * 2. blockdev backup
1279 * Both the source and the target are top BDSes.
1280 * 3. internal backup(used for block replication)
1281 * Both the source and the target are backing file
1283 * In case 1 and 2, neither the source nor the target is the backing file.
1284 * In case 3, we will block the top BDS, so there is only one block job
1285 * for the top BDS and its backing chain.
1287 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
1288 parent->backing_blocker);
1289 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
1290 parent->backing_blocker);
1293 static void bdrv_backing_detach(BdrvChild *c)
1295 BlockDriverState *parent = c->opaque;
1297 GLOBAL_STATE_CODE();
1298 assert(parent->backing_blocker);
1299 bdrv_op_unblock_all(c->bs, parent->backing_blocker);
1300 error_free(parent->backing_blocker);
1301 parent->backing_blocker = NULL;
1304 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
1305 const char *filename, Error **errp)
1307 BlockDriverState *parent = c->opaque;
1308 bool read_only = bdrv_is_read_only(parent);
1309 int ret;
1310 GLOBAL_STATE_CODE();
1312 if (read_only) {
1313 ret = bdrv_reopen_set_read_only(parent, false, errp);
1314 if (ret < 0) {
1315 return ret;
1319 ret = bdrv_change_backing_file(parent, filename,
1320 base->drv ? base->drv->format_name : "",
1321 false);
1322 if (ret < 0) {
1323 error_setg_errno(errp, -ret, "Could not update backing file link");
1326 if (read_only) {
1327 bdrv_reopen_set_read_only(parent, true, NULL);
1330 return ret;
1334 * Returns the options and flags that a generic child of a BDS should
1335 * get, based on the given options and flags for the parent BDS.
1337 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
1338 int *child_flags, QDict *child_options,
1339 int parent_flags, QDict *parent_options)
1341 int flags = parent_flags;
1342 GLOBAL_STATE_CODE();
1345 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL.
1346 * Generally, the question to answer is: Should this child be
1347 * format-probed by default?
1351 * Pure and non-filtered data children of non-format nodes should
1352 * be probed by default (even when the node itself has BDRV_O_PROTOCOL
1353 * set). This only affects a very limited set of drivers (namely
1354 * quorum and blkverify when this comment was written).
1355 * Force-clear BDRV_O_PROTOCOL then.
1357 if (!parent_is_format &&
1358 (role & BDRV_CHILD_DATA) &&
1359 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED)))
1361 flags &= ~BDRV_O_PROTOCOL;
1365 * All children of format nodes (except for COW children) and all
1366 * metadata children in general should never be format-probed.
1367 * Force-set BDRV_O_PROTOCOL then.
1369 if ((parent_is_format && !(role & BDRV_CHILD_COW)) ||
1370 (role & BDRV_CHILD_METADATA))
1372 flags |= BDRV_O_PROTOCOL;
1376 * If the cache mode isn't explicitly set, inherit direct and no-flush from
1377 * the parent.
1379 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
1380 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
1381 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
1383 if (role & BDRV_CHILD_COW) {
1384 /* backing files are opened read-only by default */
1385 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
1386 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
1387 } else {
1388 /* Inherit the read-only option from the parent if it's not set */
1389 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1390 qdict_copy_default(child_options, parent_options,
1391 BDRV_OPT_AUTO_READ_ONLY);
1395 * bdrv_co_pdiscard() respects unmap policy for the parent, so we
1396 * can default to enable it on lower layers regardless of the
1397 * parent option.
1399 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
1401 /* Clear flags that only apply to the top layer */
1402 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
1404 if (role & BDRV_CHILD_METADATA) {
1405 flags &= ~BDRV_O_NO_IO;
1407 if (role & BDRV_CHILD_COW) {
1408 flags &= ~BDRV_O_TEMPORARY;
1411 *child_flags = flags;
1414 static void GRAPH_WRLOCK bdrv_child_cb_attach(BdrvChild *child)
1416 BlockDriverState *bs = child->opaque;
1418 assert_bdrv_graph_writable();
1419 QLIST_INSERT_HEAD(&bs->children, child, next);
1420 if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) {
1422 * Here we handle filters and block/raw-format.c when it behave like
1423 * filter. They generally have a single PRIMARY child, which is also the
1424 * FILTERED child, and that they may have multiple more children, which
1425 * are neither PRIMARY nor FILTERED. And never we have a COW child here.
1426 * So bs->file will be the PRIMARY child, unless the PRIMARY child goes
1427 * into bs->backing on exceptional cases; and bs->backing will be
1428 * nothing else.
1430 assert(!(child->role & BDRV_CHILD_COW));
1431 if (child->role & BDRV_CHILD_PRIMARY) {
1432 assert(child->role & BDRV_CHILD_FILTERED);
1433 assert(!bs->backing);
1434 assert(!bs->file);
1436 if (bs->drv->filtered_child_is_backing) {
1437 bs->backing = child;
1438 } else {
1439 bs->file = child;
1441 } else {
1442 assert(!(child->role & BDRV_CHILD_FILTERED));
1444 } else if (child->role & BDRV_CHILD_COW) {
1445 assert(bs->drv->supports_backing);
1446 assert(!(child->role & BDRV_CHILD_PRIMARY));
1447 assert(!bs->backing);
1448 bs->backing = child;
1449 bdrv_backing_attach(child);
1450 } else if (child->role & BDRV_CHILD_PRIMARY) {
1451 assert(!bs->file);
1452 bs->file = child;
1456 static void GRAPH_WRLOCK bdrv_child_cb_detach(BdrvChild *child)
1458 BlockDriverState *bs = child->opaque;
1460 if (child->role & BDRV_CHILD_COW) {
1461 bdrv_backing_detach(child);
1464 assert_bdrv_graph_writable();
1465 QLIST_REMOVE(child, next);
1466 if (child == bs->backing) {
1467 assert(child != bs->file);
1468 bs->backing = NULL;
1469 } else if (child == bs->file) {
1470 bs->file = NULL;
1474 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
1475 const char *filename, Error **errp)
1477 if (c->role & BDRV_CHILD_COW) {
1478 return bdrv_backing_update_filename(c, base, filename, errp);
1480 return 0;
1483 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c)
1485 BlockDriverState *bs = c->opaque;
1486 IO_CODE();
1488 return bdrv_get_aio_context(bs);
1491 const BdrvChildClass child_of_bds = {
1492 .parent_is_bds = true,
1493 .get_parent_desc = bdrv_child_get_parent_desc,
1494 .inherit_options = bdrv_inherited_options,
1495 .drained_begin = bdrv_child_cb_drained_begin,
1496 .drained_poll = bdrv_child_cb_drained_poll,
1497 .drained_end = bdrv_child_cb_drained_end,
1498 .attach = bdrv_child_cb_attach,
1499 .detach = bdrv_child_cb_detach,
1500 .inactivate = bdrv_child_cb_inactivate,
1501 .change_aio_ctx = bdrv_child_cb_change_aio_ctx,
1502 .update_filename = bdrv_child_cb_update_filename,
1503 .get_parent_aio_context = child_of_bds_get_parent_aio_context,
1506 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c)
1508 IO_CODE();
1509 return c->klass->get_parent_aio_context(c);
1512 static int bdrv_open_flags(BlockDriverState *bs, int flags)
1514 int open_flags = flags;
1515 GLOBAL_STATE_CODE();
1518 * Clear flags that are internal to the block layer before opening the
1519 * image.
1521 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
1523 return open_flags;
1526 static void update_flags_from_options(int *flags, QemuOpts *opts)
1528 GLOBAL_STATE_CODE();
1530 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
1532 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
1533 *flags |= BDRV_O_NO_FLUSH;
1536 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
1537 *flags |= BDRV_O_NOCACHE;
1540 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
1541 *flags |= BDRV_O_RDWR;
1544 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
1545 *flags |= BDRV_O_AUTO_RDONLY;
1549 static void update_options_from_flags(QDict *options, int flags)
1551 GLOBAL_STATE_CODE();
1552 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
1553 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
1555 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
1556 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
1557 flags & BDRV_O_NO_FLUSH);
1559 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
1560 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
1562 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
1563 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
1564 flags & BDRV_O_AUTO_RDONLY);
1568 static void bdrv_assign_node_name(BlockDriverState *bs,
1569 const char *node_name,
1570 Error **errp)
1572 char *gen_node_name = NULL;
1573 GLOBAL_STATE_CODE();
1575 if (!node_name) {
1576 node_name = gen_node_name = id_generate(ID_BLOCK);
1577 } else if (!id_wellformed(node_name)) {
1579 * Check for empty string or invalid characters, but not if it is
1580 * generated (generated names use characters not available to the user)
1582 error_setg(errp, "Invalid node-name: '%s'", node_name);
1583 return;
1586 /* takes care of avoiding namespaces collisions */
1587 if (blk_by_name(node_name)) {
1588 error_setg(errp, "node-name=%s is conflicting with a device id",
1589 node_name);
1590 goto out;
1593 /* takes care of avoiding duplicates node names */
1594 if (bdrv_find_node(node_name)) {
1595 error_setg(errp, "Duplicate nodes with node-name='%s'", node_name);
1596 goto out;
1599 /* Make sure that the node name isn't truncated */
1600 if (strlen(node_name) >= sizeof(bs->node_name)) {
1601 error_setg(errp, "Node name too long");
1602 goto out;
1605 /* copy node name into the bs and insert it into the graph list */
1606 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
1607 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
1608 out:
1609 g_free(gen_node_name);
1613 * The caller must always hold @bs AioContext lock, because this function calls
1614 * bdrv_refresh_total_sectors() which polls when called from non-coroutine
1615 * context.
1617 static int no_coroutine_fn GRAPH_UNLOCKED
1618 bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name,
1619 QDict *options, int open_flags, Error **errp)
1621 AioContext *ctx;
1622 Error *local_err = NULL;
1623 int i, ret;
1624 GLOBAL_STATE_CODE();
1626 bdrv_assign_node_name(bs, node_name, &local_err);
1627 if (local_err) {
1628 error_propagate(errp, local_err);
1629 return -EINVAL;
1632 bs->drv = drv;
1633 bs->opaque = g_malloc0(drv->instance_size);
1635 if (drv->bdrv_file_open) {
1636 assert(!drv->bdrv_needs_filename || bs->filename[0]);
1637 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
1638 } else if (drv->bdrv_open) {
1639 ret = drv->bdrv_open(bs, options, open_flags, &local_err);
1640 } else {
1641 ret = 0;
1644 if (ret < 0) {
1645 if (local_err) {
1646 error_propagate(errp, local_err);
1647 } else if (bs->filename[0]) {
1648 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
1649 } else {
1650 error_setg_errno(errp, -ret, "Could not open image");
1652 goto open_failed;
1655 assert(!(bs->supported_read_flags & ~BDRV_REQ_MASK));
1656 assert(!(bs->supported_write_flags & ~BDRV_REQ_MASK));
1659 * Always allow the BDRV_REQ_REGISTERED_BUF optimization hint. This saves
1660 * drivers that pass read/write requests through to a child the trouble of
1661 * declaring support explicitly.
1663 * Drivers must not propagate this flag accidentally when they initiate I/O
1664 * to a bounce buffer. That case should be rare though.
1666 bs->supported_read_flags |= BDRV_REQ_REGISTERED_BUF;
1667 bs->supported_write_flags |= BDRV_REQ_REGISTERED_BUF;
1669 /* Get the context after .bdrv_open, it can change the context */
1670 ctx = bdrv_get_aio_context(bs);
1671 aio_context_acquire(ctx);
1673 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
1674 if (ret < 0) {
1675 error_setg_errno(errp, -ret, "Could not refresh total sector count");
1676 aio_context_release(ctx);
1677 return ret;
1680 bdrv_graph_rdlock_main_loop();
1681 bdrv_refresh_limits(bs, NULL, &local_err);
1682 bdrv_graph_rdunlock_main_loop();
1683 aio_context_release(ctx);
1685 if (local_err) {
1686 error_propagate(errp, local_err);
1687 return -EINVAL;
1690 assert(bdrv_opt_mem_align(bs) != 0);
1691 assert(bdrv_min_mem_align(bs) != 0);
1692 assert(is_power_of_2(bs->bl.request_alignment));
1694 for (i = 0; i < bs->quiesce_counter; i++) {
1695 if (drv->bdrv_drain_begin) {
1696 drv->bdrv_drain_begin(bs);
1700 return 0;
1701 open_failed:
1702 bs->drv = NULL;
1703 if (bs->file != NULL) {
1704 bdrv_graph_wrlock(NULL);
1705 bdrv_unref_child(bs, bs->file);
1706 bdrv_graph_wrunlock();
1707 assert(!bs->file);
1709 g_free(bs->opaque);
1710 bs->opaque = NULL;
1711 return ret;
1715 * Create and open a block node.
1717 * @options is a QDict of options to pass to the block drivers, or NULL for an
1718 * empty set of options. The reference to the QDict belongs to the block layer
1719 * after the call (even on failure), so if the caller intends to reuse the
1720 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
1722 BlockDriverState *bdrv_new_open_driver_opts(BlockDriver *drv,
1723 const char *node_name,
1724 QDict *options, int flags,
1725 Error **errp)
1727 BlockDriverState *bs;
1728 int ret;
1730 GLOBAL_STATE_CODE();
1732 bs = bdrv_new();
1733 bs->open_flags = flags;
1734 bs->options = options ?: qdict_new();
1735 bs->explicit_options = qdict_clone_shallow(bs->options);
1736 bs->opaque = NULL;
1738 update_options_from_flags(bs->options, flags);
1740 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
1741 if (ret < 0) {
1742 qobject_unref(bs->explicit_options);
1743 bs->explicit_options = NULL;
1744 qobject_unref(bs->options);
1745 bs->options = NULL;
1746 bdrv_unref(bs);
1747 return NULL;
1750 return bs;
1753 /* Create and open a block node. */
1754 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
1755 int flags, Error **errp)
1757 GLOBAL_STATE_CODE();
1758 return bdrv_new_open_driver_opts(drv, node_name, NULL, flags, errp);
1761 QemuOptsList bdrv_runtime_opts = {
1762 .name = "bdrv_common",
1763 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
1764 .desc = {
1766 .name = "node-name",
1767 .type = QEMU_OPT_STRING,
1768 .help = "Node name of the block device node",
1771 .name = "driver",
1772 .type = QEMU_OPT_STRING,
1773 .help = "Block driver to use for the node",
1776 .name = BDRV_OPT_CACHE_DIRECT,
1777 .type = QEMU_OPT_BOOL,
1778 .help = "Bypass software writeback cache on the host",
1781 .name = BDRV_OPT_CACHE_NO_FLUSH,
1782 .type = QEMU_OPT_BOOL,
1783 .help = "Ignore flush requests",
1786 .name = BDRV_OPT_READ_ONLY,
1787 .type = QEMU_OPT_BOOL,
1788 .help = "Node is opened in read-only mode",
1791 .name = BDRV_OPT_AUTO_READ_ONLY,
1792 .type = QEMU_OPT_BOOL,
1793 .help = "Node can become read-only if opening read-write fails",
1796 .name = "detect-zeroes",
1797 .type = QEMU_OPT_STRING,
1798 .help = "try to optimize zero writes (off, on, unmap)",
1801 .name = BDRV_OPT_DISCARD,
1802 .type = QEMU_OPT_STRING,
1803 .help = "discard operation (ignore/off, unmap/on)",
1806 .name = BDRV_OPT_FORCE_SHARE,
1807 .type = QEMU_OPT_BOOL,
1808 .help = "always accept other writers (default: off)",
1810 { /* end of list */ }
1814 QemuOptsList bdrv_create_opts_simple = {
1815 .name = "simple-create-opts",
1816 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head),
1817 .desc = {
1819 .name = BLOCK_OPT_SIZE,
1820 .type = QEMU_OPT_SIZE,
1821 .help = "Virtual disk size"
1824 .name = BLOCK_OPT_PREALLOC,
1825 .type = QEMU_OPT_STRING,
1826 .help = "Preallocation mode (allowed values: off)"
1828 { /* end of list */ }
1833 * Common part for opening disk images and files
1835 * Removes all processed options from *options.
1837 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
1838 QDict *options, Error **errp)
1840 int ret, open_flags;
1841 const char *filename;
1842 const char *driver_name = NULL;
1843 const char *node_name = NULL;
1844 const char *discard;
1845 QemuOpts *opts;
1846 BlockDriver *drv;
1847 Error *local_err = NULL;
1848 bool ro;
1850 assert(bs->file == NULL);
1851 assert(options != NULL && bs->options != options);
1852 GLOBAL_STATE_CODE();
1854 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
1855 if (!qemu_opts_absorb_qdict(opts, options, errp)) {
1856 ret = -EINVAL;
1857 goto fail_opts;
1860 update_flags_from_options(&bs->open_flags, opts);
1862 driver_name = qemu_opt_get(opts, "driver");
1863 drv = bdrv_find_format(driver_name);
1864 assert(drv != NULL);
1866 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
1868 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
1869 error_setg(errp,
1870 BDRV_OPT_FORCE_SHARE
1871 "=on can only be used with read-only images");
1872 ret = -EINVAL;
1873 goto fail_opts;
1876 if (file != NULL) {
1877 bdrv_refresh_filename(blk_bs(file));
1878 filename = blk_bs(file)->filename;
1879 } else {
1881 * Caution: while qdict_get_try_str() is fine, getting
1882 * non-string types would require more care. When @options
1883 * come from -blockdev or blockdev_add, its members are typed
1884 * according to the QAPI schema, but when they come from
1885 * -drive, they're all QString.
1887 filename = qdict_get_try_str(options, "filename");
1890 if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
1891 error_setg(errp, "The '%s' block driver requires a file name",
1892 drv->format_name);
1893 ret = -EINVAL;
1894 goto fail_opts;
1897 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
1898 drv->format_name);
1900 ro = bdrv_is_read_only(bs);
1902 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, ro)) {
1903 if (!ro && bdrv_is_whitelisted(drv, true)) {
1904 ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
1905 } else {
1906 ret = -ENOTSUP;
1908 if (ret < 0) {
1909 error_setg(errp,
1910 !ro && bdrv_is_whitelisted(drv, true)
1911 ? "Driver '%s' can only be used for read-only devices"
1912 : "Driver '%s' is not whitelisted",
1913 drv->format_name);
1914 goto fail_opts;
1918 /* bdrv_new() and bdrv_close() make it so */
1919 assert(qatomic_read(&bs->copy_on_read) == 0);
1921 if (bs->open_flags & BDRV_O_COPY_ON_READ) {
1922 if (!ro) {
1923 bdrv_enable_copy_on_read(bs);
1924 } else {
1925 error_setg(errp, "Can't use copy-on-read on read-only device");
1926 ret = -EINVAL;
1927 goto fail_opts;
1931 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
1932 if (discard != NULL) {
1933 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
1934 error_setg(errp, "Invalid discard option");
1935 ret = -EINVAL;
1936 goto fail_opts;
1940 bs->detect_zeroes =
1941 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
1942 if (local_err) {
1943 error_propagate(errp, local_err);
1944 ret = -EINVAL;
1945 goto fail_opts;
1948 if (filename != NULL) {
1949 pstrcpy(bs->filename, sizeof(bs->filename), filename);
1950 } else {
1951 bs->filename[0] = '\0';
1953 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
1955 /* Open the image, either directly or using a protocol */
1956 open_flags = bdrv_open_flags(bs, bs->open_flags);
1957 node_name = qemu_opt_get(opts, "node-name");
1959 assert(!drv->bdrv_file_open || file == NULL);
1960 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
1961 if (ret < 0) {
1962 goto fail_opts;
1965 qemu_opts_del(opts);
1966 return 0;
1968 fail_opts:
1969 qemu_opts_del(opts);
1970 return ret;
1973 static QDict *parse_json_filename(const char *filename, Error **errp)
1975 QObject *options_obj;
1976 QDict *options;
1977 int ret;
1978 GLOBAL_STATE_CODE();
1980 ret = strstart(filename, "json:", &filename);
1981 assert(ret);
1983 options_obj = qobject_from_json(filename, errp);
1984 if (!options_obj) {
1985 error_prepend(errp, "Could not parse the JSON options: ");
1986 return NULL;
1989 options = qobject_to(QDict, options_obj);
1990 if (!options) {
1991 qobject_unref(options_obj);
1992 error_setg(errp, "Invalid JSON object given");
1993 return NULL;
1996 qdict_flatten(options);
1998 return options;
2001 static void parse_json_protocol(QDict *options, const char **pfilename,
2002 Error **errp)
2004 QDict *json_options;
2005 Error *local_err = NULL;
2006 GLOBAL_STATE_CODE();
2008 /* Parse json: pseudo-protocol */
2009 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
2010 return;
2013 json_options = parse_json_filename(*pfilename, &local_err);
2014 if (local_err) {
2015 error_propagate(errp, local_err);
2016 return;
2019 /* Options given in the filename have lower priority than options
2020 * specified directly */
2021 qdict_join(options, json_options, false);
2022 qobject_unref(json_options);
2023 *pfilename = NULL;
2027 * Fills in default options for opening images and converts the legacy
2028 * filename/flags pair to option QDict entries.
2029 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
2030 * block driver has been specified explicitly.
2032 static int bdrv_fill_options(QDict **options, const char *filename,
2033 int *flags, Error **errp)
2035 const char *drvname;
2036 bool protocol = *flags & BDRV_O_PROTOCOL;
2037 bool parse_filename = false;
2038 BlockDriver *drv = NULL;
2039 Error *local_err = NULL;
2041 GLOBAL_STATE_CODE();
2044 * Caution: while qdict_get_try_str() is fine, getting non-string
2045 * types would require more care. When @options come from
2046 * -blockdev or blockdev_add, its members are typed according to
2047 * the QAPI schema, but when they come from -drive, they're all
2048 * QString.
2050 drvname = qdict_get_try_str(*options, "driver");
2051 if (drvname) {
2052 drv = bdrv_find_format(drvname);
2053 if (!drv) {
2054 error_setg(errp, "Unknown driver '%s'", drvname);
2055 return -ENOENT;
2057 /* If the user has explicitly specified the driver, this choice should
2058 * override the BDRV_O_PROTOCOL flag */
2059 protocol = drv->bdrv_file_open;
2062 if (protocol) {
2063 *flags |= BDRV_O_PROTOCOL;
2064 } else {
2065 *flags &= ~BDRV_O_PROTOCOL;
2068 /* Translate cache options from flags into options */
2069 update_options_from_flags(*options, *flags);
2071 /* Fetch the file name from the options QDict if necessary */
2072 if (protocol && filename) {
2073 if (!qdict_haskey(*options, "filename")) {
2074 qdict_put_str(*options, "filename", filename);
2075 parse_filename = true;
2076 } else {
2077 error_setg(errp, "Can't specify 'file' and 'filename' options at "
2078 "the same time");
2079 return -EINVAL;
2083 /* Find the right block driver */
2084 /* See cautionary note on accessing @options above */
2085 filename = qdict_get_try_str(*options, "filename");
2087 if (!drvname && protocol) {
2088 if (filename) {
2089 drv = bdrv_find_protocol(filename, parse_filename, errp);
2090 if (!drv) {
2091 return -EINVAL;
2094 drvname = drv->format_name;
2095 qdict_put_str(*options, "driver", drvname);
2096 } else {
2097 error_setg(errp, "Must specify either driver or file");
2098 return -EINVAL;
2102 assert(drv || !protocol);
2104 /* Driver-specific filename parsing */
2105 if (drv && drv->bdrv_parse_filename && parse_filename) {
2106 drv->bdrv_parse_filename(filename, *options, &local_err);
2107 if (local_err) {
2108 error_propagate(errp, local_err);
2109 return -EINVAL;
2112 if (!drv->bdrv_needs_filename) {
2113 qdict_del(*options, "filename");
2117 return 0;
2120 typedef struct BlockReopenQueueEntry {
2121 bool prepared;
2122 BDRVReopenState state;
2123 QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
2124 } BlockReopenQueueEntry;
2127 * Return the flags that @bs will have after the reopens in @q have
2128 * successfully completed. If @q is NULL (or @bs is not contained in @q),
2129 * return the current flags.
2131 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
2133 BlockReopenQueueEntry *entry;
2135 if (q != NULL) {
2136 QTAILQ_FOREACH(entry, q, entry) {
2137 if (entry->state.bs == bs) {
2138 return entry->state.flags;
2143 return bs->open_flags;
2146 /* Returns whether the image file can be written to after the reopen queue @q
2147 * has been successfully applied, or right now if @q is NULL. */
2148 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
2149 BlockReopenQueue *q)
2151 int flags = bdrv_reopen_get_flags(q, bs);
2153 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
2157 * Return whether the BDS can be written to. This is not necessarily
2158 * the same as !bdrv_is_read_only(bs), as inactivated images may not
2159 * be written to but do not count as read-only images.
2161 bool bdrv_is_writable(BlockDriverState *bs)
2163 IO_CODE();
2164 return bdrv_is_writable_after_reopen(bs, NULL);
2167 static char *bdrv_child_user_desc(BdrvChild *c)
2169 GLOBAL_STATE_CODE();
2170 return c->klass->get_parent_desc(c);
2174 * Check that @a allows everything that @b needs. @a and @b must reference same
2175 * child node.
2177 static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
2179 const char *child_bs_name;
2180 g_autofree char *a_user = NULL;
2181 g_autofree char *b_user = NULL;
2182 g_autofree char *perms = NULL;
2184 assert(a->bs);
2185 assert(a->bs == b->bs);
2186 GLOBAL_STATE_CODE();
2188 if ((b->perm & a->shared_perm) == b->perm) {
2189 return true;
2192 child_bs_name = bdrv_get_node_name(b->bs);
2193 a_user = bdrv_child_user_desc(a);
2194 b_user = bdrv_child_user_desc(b);
2195 perms = bdrv_perm_names(b->perm & ~a->shared_perm);
2197 error_setg(errp, "Permission conflict on node '%s': permissions '%s' are "
2198 "both required by %s (uses node '%s' as '%s' child) and "
2199 "unshared by %s (uses node '%s' as '%s' child).",
2200 child_bs_name, perms,
2201 b_user, child_bs_name, b->name,
2202 a_user, child_bs_name, a->name);
2204 return false;
2207 static bool GRAPH_RDLOCK
2208 bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
2210 BdrvChild *a, *b;
2211 GLOBAL_STATE_CODE();
2214 * During the loop we'll look at each pair twice. That's correct because
2215 * bdrv_a_allow_b() is asymmetric and we should check each pair in both
2216 * directions.
2218 QLIST_FOREACH(a, &bs->parents, next_parent) {
2219 QLIST_FOREACH(b, &bs->parents, next_parent) {
2220 if (a == b) {
2221 continue;
2224 if (!bdrv_a_allow_b(a, b, errp)) {
2225 return true;
2230 return false;
2233 static void GRAPH_RDLOCK
2234 bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
2235 BdrvChild *c, BdrvChildRole role,
2236 BlockReopenQueue *reopen_queue,
2237 uint64_t parent_perm, uint64_t parent_shared,
2238 uint64_t *nperm, uint64_t *nshared)
2240 assert(bs->drv && bs->drv->bdrv_child_perm);
2241 GLOBAL_STATE_CODE();
2242 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
2243 parent_perm, parent_shared,
2244 nperm, nshared);
2245 /* TODO Take force_share from reopen_queue */
2246 if (child_bs && child_bs->force_share) {
2247 *nshared = BLK_PERM_ALL;
2252 * Adds the whole subtree of @bs (including @bs itself) to the @list (except for
2253 * nodes that are already in the @list, of course) so that final list is
2254 * topologically sorted. Return the result (GSList @list object is updated, so
2255 * don't use old reference after function call).
2257 * On function start @list must be already topologically sorted and for any node
2258 * in the @list the whole subtree of the node must be in the @list as well. The
2259 * simplest way to satisfy this criteria: use only result of
2260 * bdrv_topological_dfs() or NULL as @list parameter.
2262 static GSList * GRAPH_RDLOCK
2263 bdrv_topological_dfs(GSList *list, GHashTable *found, BlockDriverState *bs)
2265 BdrvChild *child;
2266 g_autoptr(GHashTable) local_found = NULL;
2268 GLOBAL_STATE_CODE();
2270 if (!found) {
2271 assert(!list);
2272 found = local_found = g_hash_table_new(NULL, NULL);
2275 if (g_hash_table_contains(found, bs)) {
2276 return list;
2278 g_hash_table_add(found, bs);
2280 QLIST_FOREACH(child, &bs->children, next) {
2281 list = bdrv_topological_dfs(list, found, child->bs);
2284 return g_slist_prepend(list, bs);
2287 typedef struct BdrvChildSetPermState {
2288 BdrvChild *child;
2289 uint64_t old_perm;
2290 uint64_t old_shared_perm;
2291 } BdrvChildSetPermState;
2293 static void bdrv_child_set_perm_abort(void *opaque)
2295 BdrvChildSetPermState *s = opaque;
2297 GLOBAL_STATE_CODE();
2299 s->child->perm = s->old_perm;
2300 s->child->shared_perm = s->old_shared_perm;
2303 static TransactionActionDrv bdrv_child_set_pem_drv = {
2304 .abort = bdrv_child_set_perm_abort,
2305 .clean = g_free,
2308 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm,
2309 uint64_t shared, Transaction *tran)
2311 BdrvChildSetPermState *s = g_new(BdrvChildSetPermState, 1);
2312 GLOBAL_STATE_CODE();
2314 *s = (BdrvChildSetPermState) {
2315 .child = c,
2316 .old_perm = c->perm,
2317 .old_shared_perm = c->shared_perm,
2320 c->perm = perm;
2321 c->shared_perm = shared;
2323 tran_add(tran, &bdrv_child_set_pem_drv, s);
2326 static void GRAPH_RDLOCK bdrv_drv_set_perm_commit(void *opaque)
2328 BlockDriverState *bs = opaque;
2329 uint64_t cumulative_perms, cumulative_shared_perms;
2330 GLOBAL_STATE_CODE();
2332 if (bs->drv->bdrv_set_perm) {
2333 bdrv_get_cumulative_perm(bs, &cumulative_perms,
2334 &cumulative_shared_perms);
2335 bs->drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
2339 static void GRAPH_RDLOCK bdrv_drv_set_perm_abort(void *opaque)
2341 BlockDriverState *bs = opaque;
2342 GLOBAL_STATE_CODE();
2344 if (bs->drv->bdrv_abort_perm_update) {
2345 bs->drv->bdrv_abort_perm_update(bs);
2349 TransactionActionDrv bdrv_drv_set_perm_drv = {
2350 .abort = bdrv_drv_set_perm_abort,
2351 .commit = bdrv_drv_set_perm_commit,
2355 * After calling this function, the transaction @tran may only be completed
2356 * while holding a reader lock for the graph.
2358 static int GRAPH_RDLOCK
2359 bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared_perm,
2360 Transaction *tran, Error **errp)
2362 GLOBAL_STATE_CODE();
2363 if (!bs->drv) {
2364 return 0;
2367 if (bs->drv->bdrv_check_perm) {
2368 int ret = bs->drv->bdrv_check_perm(bs, perm, shared_perm, errp);
2369 if (ret < 0) {
2370 return ret;
2374 if (tran) {
2375 tran_add(tran, &bdrv_drv_set_perm_drv, bs);
2378 return 0;
2381 typedef struct BdrvReplaceChildState {
2382 BdrvChild *child;
2383 BlockDriverState *old_bs;
2384 } BdrvReplaceChildState;
2386 static void GRAPH_WRLOCK bdrv_replace_child_commit(void *opaque)
2388 BdrvReplaceChildState *s = opaque;
2389 GLOBAL_STATE_CODE();
2391 bdrv_schedule_unref(s->old_bs);
2394 static void GRAPH_WRLOCK bdrv_replace_child_abort(void *opaque)
2396 BdrvReplaceChildState *s = opaque;
2397 BlockDriverState *new_bs = s->child->bs;
2399 GLOBAL_STATE_CODE();
2400 assert_bdrv_graph_writable();
2402 /* old_bs reference is transparently moved from @s to @s->child */
2403 if (!s->child->bs) {
2405 * The parents were undrained when removing old_bs from the child. New
2406 * requests can't have been made, though, because the child was empty.
2408 * TODO Make bdrv_replace_child_noperm() transactionable to avoid
2409 * undraining the parent in the first place. Once this is done, having
2410 * new_bs drained when calling bdrv_replace_child_tran() is not a
2411 * requirement any more.
2413 bdrv_parent_drained_begin_single(s->child);
2414 assert(!bdrv_parent_drained_poll_single(s->child));
2416 assert(s->child->quiesced_parent);
2417 bdrv_replace_child_noperm(s->child, s->old_bs);
2419 bdrv_unref(new_bs);
2422 static TransactionActionDrv bdrv_replace_child_drv = {
2423 .commit = bdrv_replace_child_commit,
2424 .abort = bdrv_replace_child_abort,
2425 .clean = g_free,
2429 * bdrv_replace_child_tran
2431 * Note: real unref of old_bs is done only on commit.
2433 * Both @child->bs and @new_bs (if non-NULL) must be drained. @new_bs must be
2434 * kept drained until the transaction is completed.
2436 * After calling this function, the transaction @tran may only be completed
2437 * while holding a writer lock for the graph.
2439 * The function doesn't update permissions, caller is responsible for this.
2441 static void GRAPH_WRLOCK
2442 bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
2443 Transaction *tran)
2445 BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
2447 assert(child->quiesced_parent);
2448 assert(!new_bs || new_bs->quiesce_counter);
2450 *s = (BdrvReplaceChildState) {
2451 .child = child,
2452 .old_bs = child->bs,
2454 tran_add(tran, &bdrv_replace_child_drv, s);
2456 if (new_bs) {
2457 bdrv_ref(new_bs);
2460 bdrv_replace_child_noperm(child, new_bs);
2461 /* old_bs reference is transparently moved from @child to @s */
2465 * Refresh permissions in @bs subtree. The function is intended to be called
2466 * after some graph modification that was done without permission update.
2468 * After calling this function, the transaction @tran may only be completed
2469 * while holding a reader lock for the graph.
2471 static int GRAPH_RDLOCK
2472 bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
2473 Transaction *tran, Error **errp)
2475 BlockDriver *drv = bs->drv;
2476 BdrvChild *c;
2477 int ret;
2478 uint64_t cumulative_perms, cumulative_shared_perms;
2479 GLOBAL_STATE_CODE();
2481 bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms);
2483 /* Write permissions never work with read-only images */
2484 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2485 !bdrv_is_writable_after_reopen(bs, q))
2487 if (!bdrv_is_writable_after_reopen(bs, NULL)) {
2488 error_setg(errp, "Block node is read-only");
2489 } else {
2490 error_setg(errp, "Read-only block node '%s' cannot support "
2491 "read-write users", bdrv_get_node_name(bs));
2494 return -EPERM;
2498 * Unaligned requests will automatically be aligned to bl.request_alignment
2499 * and without RESIZE we can't extend requests to write to space beyond the
2500 * end of the image, so it's required that the image size is aligned.
2502 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2503 !(cumulative_perms & BLK_PERM_RESIZE))
2505 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) {
2506 error_setg(errp, "Cannot get 'write' permission without 'resize': "
2507 "Image size is not a multiple of request "
2508 "alignment");
2509 return -EPERM;
2513 /* Check this node */
2514 if (!drv) {
2515 return 0;
2518 ret = bdrv_drv_set_perm(bs, cumulative_perms, cumulative_shared_perms, tran,
2519 errp);
2520 if (ret < 0) {
2521 return ret;
2524 /* Drivers that never have children can omit .bdrv_child_perm() */
2525 if (!drv->bdrv_child_perm) {
2526 assert(QLIST_EMPTY(&bs->children));
2527 return 0;
2530 /* Check all children */
2531 QLIST_FOREACH(c, &bs->children, next) {
2532 uint64_t cur_perm, cur_shared;
2534 bdrv_child_perm(bs, c->bs, c, c->role, q,
2535 cumulative_perms, cumulative_shared_perms,
2536 &cur_perm, &cur_shared);
2537 bdrv_child_set_perm(c, cur_perm, cur_shared, tran);
2540 return 0;
2544 * @list is a product of bdrv_topological_dfs() (may be called several times) -
2545 * a topologically sorted subgraph.
2547 * After calling this function, the transaction @tran may only be completed
2548 * while holding a reader lock for the graph.
2550 static int GRAPH_RDLOCK
2551 bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
2552 Error **errp)
2554 int ret;
2555 BlockDriverState *bs;
2556 GLOBAL_STATE_CODE();
2558 for ( ; list; list = list->next) {
2559 bs = list->data;
2561 if (bdrv_parent_perms_conflict(bs, errp)) {
2562 return -EINVAL;
2565 ret = bdrv_node_refresh_perm(bs, q, tran, errp);
2566 if (ret < 0) {
2567 return ret;
2571 return 0;
2575 * @list is any list of nodes. List is completed by all subtrees and
2576 * topologically sorted. It's not a problem if some node occurs in the @list
2577 * several times.
2579 * After calling this function, the transaction @tran may only be completed
2580 * while holding a reader lock for the graph.
2582 static int GRAPH_RDLOCK
2583 bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
2584 Error **errp)
2586 g_autoptr(GHashTable) found = g_hash_table_new(NULL, NULL);
2587 g_autoptr(GSList) refresh_list = NULL;
2589 for ( ; list; list = list->next) {
2590 refresh_list = bdrv_topological_dfs(refresh_list, found, list->data);
2593 return bdrv_do_refresh_perms(refresh_list, q, tran, errp);
2596 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
2597 uint64_t *shared_perm)
2599 BdrvChild *c;
2600 uint64_t cumulative_perms = 0;
2601 uint64_t cumulative_shared_perms = BLK_PERM_ALL;
2603 GLOBAL_STATE_CODE();
2605 QLIST_FOREACH(c, &bs->parents, next_parent) {
2606 cumulative_perms |= c->perm;
2607 cumulative_shared_perms &= c->shared_perm;
2610 *perm = cumulative_perms;
2611 *shared_perm = cumulative_shared_perms;
2614 char *bdrv_perm_names(uint64_t perm)
2616 struct perm_name {
2617 uint64_t perm;
2618 const char *name;
2619 } permissions[] = {
2620 { BLK_PERM_CONSISTENT_READ, "consistent read" },
2621 { BLK_PERM_WRITE, "write" },
2622 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
2623 { BLK_PERM_RESIZE, "resize" },
2624 { 0, NULL }
2627 GString *result = g_string_sized_new(30);
2628 struct perm_name *p;
2630 for (p = permissions; p->name; p++) {
2631 if (perm & p->perm) {
2632 if (result->len > 0) {
2633 g_string_append(result, ", ");
2635 g_string_append(result, p->name);
2639 return g_string_free(result, FALSE);
2644 * @tran is allowed to be NULL. In this case no rollback is possible.
2646 * After calling this function, the transaction @tran may only be completed
2647 * while holding a reader lock for the graph.
2649 static int GRAPH_RDLOCK
2650 bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp)
2652 int ret;
2653 Transaction *local_tran = NULL;
2654 g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs);
2655 GLOBAL_STATE_CODE();
2657 if (!tran) {
2658 tran = local_tran = tran_new();
2661 ret = bdrv_do_refresh_perms(list, NULL, tran, errp);
2663 if (local_tran) {
2664 tran_finalize(local_tran, ret);
2667 return ret;
2670 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
2671 Error **errp)
2673 Error *local_err = NULL;
2674 Transaction *tran = tran_new();
2675 int ret;
2677 GLOBAL_STATE_CODE();
2679 bdrv_child_set_perm(c, perm, shared, tran);
2681 ret = bdrv_refresh_perms(c->bs, tran, &local_err);
2683 tran_finalize(tran, ret);
2685 if (ret < 0) {
2686 if ((perm & ~c->perm) || (c->shared_perm & ~shared)) {
2687 /* tighten permissions */
2688 error_propagate(errp, local_err);
2689 } else {
2691 * Our caller may intend to only loosen restrictions and
2692 * does not expect this function to fail. Errors are not
2693 * fatal in such a case, so we can just hide them from our
2694 * caller.
2696 error_free(local_err);
2697 ret = 0;
2701 return ret;
2704 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
2706 uint64_t parent_perms, parent_shared;
2707 uint64_t perms, shared;
2709 GLOBAL_STATE_CODE();
2711 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
2712 bdrv_child_perm(bs, c->bs, c, c->role, NULL,
2713 parent_perms, parent_shared, &perms, &shared);
2715 return bdrv_child_try_set_perm(c, perms, shared, errp);
2719 * Default implementation for .bdrv_child_perm() for block filters:
2720 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the
2721 * filtered child.
2723 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
2724 BdrvChildRole role,
2725 BlockReopenQueue *reopen_queue,
2726 uint64_t perm, uint64_t shared,
2727 uint64_t *nperm, uint64_t *nshared)
2729 GLOBAL_STATE_CODE();
2730 *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
2731 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
2734 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c,
2735 BdrvChildRole role,
2736 BlockReopenQueue *reopen_queue,
2737 uint64_t perm, uint64_t shared,
2738 uint64_t *nperm, uint64_t *nshared)
2740 assert(role & BDRV_CHILD_COW);
2741 GLOBAL_STATE_CODE();
2744 * We want consistent read from backing files if the parent needs it.
2745 * No other operations are performed on backing files.
2747 perm &= BLK_PERM_CONSISTENT_READ;
2750 * If the parent can deal with changing data, we're okay with a
2751 * writable and resizable backing file.
2752 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too?
2754 if (shared & BLK_PERM_WRITE) {
2755 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
2756 } else {
2757 shared = 0;
2760 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
2762 if (bs->open_flags & BDRV_O_INACTIVE) {
2763 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2766 *nperm = perm;
2767 *nshared = shared;
2770 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c,
2771 BdrvChildRole role,
2772 BlockReopenQueue *reopen_queue,
2773 uint64_t perm, uint64_t shared,
2774 uint64_t *nperm, uint64_t *nshared)
2776 int flags;
2778 GLOBAL_STATE_CODE();
2779 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA));
2781 flags = bdrv_reopen_get_flags(reopen_queue, bs);
2784 * Apart from the modifications below, the same permissions are
2785 * forwarded and left alone as for filters
2787 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2788 perm, shared, &perm, &shared);
2790 if (role & BDRV_CHILD_METADATA) {
2791 /* Format drivers may touch metadata even if the guest doesn't write */
2792 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
2793 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2797 * bs->file always needs to be consistent because of the
2798 * metadata. We can never allow other users to resize or write
2799 * to it.
2801 if (!(flags & BDRV_O_NO_IO)) {
2802 perm |= BLK_PERM_CONSISTENT_READ;
2804 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
2807 if (role & BDRV_CHILD_DATA) {
2809 * Technically, everything in this block is a subset of the
2810 * BDRV_CHILD_METADATA path taken above, and so this could
2811 * be an "else if" branch. However, that is not obvious, and
2812 * this function is not performance critical, therefore we let
2813 * this be an independent "if".
2817 * We cannot allow other users to resize the file because the
2818 * format driver might have some assumptions about the size
2819 * (e.g. because it is stored in metadata, or because the file
2820 * is split into fixed-size data files).
2822 shared &= ~BLK_PERM_RESIZE;
2825 * WRITE_UNCHANGED often cannot be performed as such on the
2826 * data file. For example, the qcow2 driver may still need to
2827 * write copied clusters on copy-on-read.
2829 if (perm & BLK_PERM_WRITE_UNCHANGED) {
2830 perm |= BLK_PERM_WRITE;
2834 * If the data file is written to, the format driver may
2835 * expect to be able to resize it by writing beyond the EOF.
2837 if (perm & BLK_PERM_WRITE) {
2838 perm |= BLK_PERM_RESIZE;
2842 if (bs->open_flags & BDRV_O_INACTIVE) {
2843 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2846 *nperm = perm;
2847 *nshared = shared;
2850 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
2851 BdrvChildRole role, BlockReopenQueue *reopen_queue,
2852 uint64_t perm, uint64_t shared,
2853 uint64_t *nperm, uint64_t *nshared)
2855 GLOBAL_STATE_CODE();
2856 if (role & BDRV_CHILD_FILTERED) {
2857 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
2858 BDRV_CHILD_COW)));
2859 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2860 perm, shared, nperm, nshared);
2861 } else if (role & BDRV_CHILD_COW) {
2862 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA)));
2863 bdrv_default_perms_for_cow(bs, c, role, reopen_queue,
2864 perm, shared, nperm, nshared);
2865 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) {
2866 bdrv_default_perms_for_storage(bs, c, role, reopen_queue,
2867 perm, shared, nperm, nshared);
2868 } else {
2869 g_assert_not_reached();
2873 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
2875 static const uint64_t permissions[] = {
2876 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ,
2877 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE,
2878 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED,
2879 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE,
2882 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX);
2883 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1);
2885 assert(qapi_perm < BLOCK_PERMISSION__MAX);
2887 return permissions[qapi_perm];
2891 * Replaces the node that a BdrvChild points to without updating permissions.
2893 * If @new_bs is non-NULL, the parent of @child must already be drained through
2894 * @child and the caller must hold the AioContext lock for @new_bs.
2896 static void GRAPH_WRLOCK
2897 bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs)
2899 BlockDriverState *old_bs = child->bs;
2900 int new_bs_quiesce_counter;
2902 assert(!child->frozen);
2905 * If we want to change the BdrvChild to point to a drained node as its new
2906 * child->bs, we need to make sure that its new parent is drained, too. In
2907 * other words, either child->quiesce_parent must already be true or we must
2908 * be able to set it and keep the parent's quiesce_counter consistent with
2909 * that, but without polling or starting new requests (this function
2910 * guarantees that it doesn't poll, and starting new requests would be
2911 * against the invariants of drain sections).
2913 * To keep things simple, we pick the first option (child->quiesce_parent
2914 * must already be true). We also generalise the rule a bit to make it
2915 * easier to verify in callers and more likely to be covered in test cases:
2916 * The parent must be quiesced through this child even if new_bs isn't
2917 * currently drained.
2919 * The only exception is for callers that always pass new_bs == NULL. In
2920 * this case, we obviously never need to consider the case of a drained
2921 * new_bs, so we can keep the callers simpler by allowing them not to drain
2922 * the parent.
2924 assert(!new_bs || child->quiesced_parent);
2925 assert(old_bs != new_bs);
2926 GLOBAL_STATE_CODE();
2928 if (old_bs && new_bs) {
2929 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
2932 if (old_bs) {
2933 if (child->klass->detach) {
2934 child->klass->detach(child);
2936 QLIST_REMOVE(child, next_parent);
2939 child->bs = new_bs;
2941 if (new_bs) {
2942 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
2943 if (child->klass->attach) {
2944 child->klass->attach(child);
2949 * If the parent was drained through this BdrvChild previously, but new_bs
2950 * is not drained, allow requests to come in only after the new node has
2951 * been attached.
2953 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0);
2954 if (!new_bs_quiesce_counter && child->quiesced_parent) {
2955 bdrv_parent_drained_end_single(child);
2960 * Free the given @child.
2962 * The child must be empty (i.e. `child->bs == NULL`) and it must be
2963 * unused (i.e. not in a children list).
2965 static void bdrv_child_free(BdrvChild *child)
2967 assert(!child->bs);
2968 GLOBAL_STATE_CODE();
2969 assert(!child->next.le_prev); /* not in children list */
2971 g_free(child->name);
2972 g_free(child);
2975 typedef struct BdrvAttachChildCommonState {
2976 BdrvChild *child;
2977 AioContext *old_parent_ctx;
2978 AioContext *old_child_ctx;
2979 } BdrvAttachChildCommonState;
2981 static void GRAPH_WRLOCK bdrv_attach_child_common_abort(void *opaque)
2983 BdrvAttachChildCommonState *s = opaque;
2984 BlockDriverState *bs = s->child->bs;
2986 GLOBAL_STATE_CODE();
2987 assert_bdrv_graph_writable();
2989 bdrv_replace_child_noperm(s->child, NULL);
2991 if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
2992 bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort);
2995 if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) {
2996 Transaction *tran;
2997 GHashTable *visited;
2998 bool ret;
3000 tran = tran_new();
3002 /* No need to visit `child`, because it has been detached already */
3003 visited = g_hash_table_new(NULL, NULL);
3004 ret = s->child->klass->change_aio_ctx(s->child, s->old_parent_ctx,
3005 visited, tran, &error_abort);
3006 g_hash_table_destroy(visited);
3008 /* transaction is supposed to always succeed */
3009 assert(ret == true);
3010 tran_commit(tran);
3013 bdrv_schedule_unref(bs);
3014 bdrv_child_free(s->child);
3017 static TransactionActionDrv bdrv_attach_child_common_drv = {
3018 .abort = bdrv_attach_child_common_abort,
3019 .clean = g_free,
3023 * Common part of attaching bdrv child to bs or to blk or to job
3025 * Function doesn't update permissions, caller is responsible for this.
3027 * After calling this function, the transaction @tran may only be completed
3028 * while holding a writer lock for the graph.
3030 * Returns new created child.
3032 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
3033 * @child_bs can move to a different AioContext in this function. Callers must
3034 * make sure that their AioContext locking is still correct after this.
3036 static BdrvChild * GRAPH_WRLOCK
3037 bdrv_attach_child_common(BlockDriverState *child_bs,
3038 const char *child_name,
3039 const BdrvChildClass *child_class,
3040 BdrvChildRole child_role,
3041 uint64_t perm, uint64_t shared_perm,
3042 void *opaque,
3043 Transaction *tran, Error **errp)
3045 BdrvChild *new_child;
3046 AioContext *parent_ctx, *new_child_ctx;
3047 AioContext *child_ctx = bdrv_get_aio_context(child_bs);
3049 assert(child_class->get_parent_desc);
3050 GLOBAL_STATE_CODE();
3052 new_child = g_new(BdrvChild, 1);
3053 *new_child = (BdrvChild) {
3054 .bs = NULL,
3055 .name = g_strdup(child_name),
3056 .klass = child_class,
3057 .role = child_role,
3058 .perm = perm,
3059 .shared_perm = shared_perm,
3060 .opaque = opaque,
3064 * If the AioContexts don't match, first try to move the subtree of
3065 * child_bs into the AioContext of the new parent. If this doesn't work,
3066 * try moving the parent into the AioContext of child_bs instead.
3068 parent_ctx = bdrv_child_get_parent_aio_context(new_child);
3069 if (child_ctx != parent_ctx) {
3070 Error *local_err = NULL;
3071 int ret = bdrv_try_change_aio_context(child_bs, parent_ctx, NULL,
3072 &local_err);
3074 if (ret < 0 && child_class->change_aio_ctx) {
3075 Transaction *aio_ctx_tran = tran_new();
3076 GHashTable *visited = g_hash_table_new(NULL, NULL);
3077 bool ret_child;
3079 g_hash_table_add(visited, new_child);
3080 ret_child = child_class->change_aio_ctx(new_child, child_ctx,
3081 visited, aio_ctx_tran,
3082 NULL);
3083 if (ret_child == true) {
3084 error_free(local_err);
3085 ret = 0;
3087 tran_finalize(aio_ctx_tran, ret_child == true ? 0 : -1);
3088 g_hash_table_destroy(visited);
3091 if (ret < 0) {
3092 error_propagate(errp, local_err);
3093 bdrv_child_free(new_child);
3094 return NULL;
3098 new_child_ctx = bdrv_get_aio_context(child_bs);
3099 if (new_child_ctx != child_ctx) {
3100 aio_context_release(child_ctx);
3101 aio_context_acquire(new_child_ctx);
3104 bdrv_ref(child_bs);
3106 * Let every new BdrvChild start with a drained parent. Inserting the child
3107 * in the graph with bdrv_replace_child_noperm() will undrain it if
3108 * @child_bs is not drained.
3110 * The child was only just created and is not yet visible in global state
3111 * until bdrv_replace_child_noperm() inserts it into the graph, so nobody
3112 * could have sent requests and polling is not necessary.
3114 * Note that this means that the parent isn't fully drained yet, we only
3115 * stop new requests from coming in. This is fine, we don't care about the
3116 * old requests here, they are not for this child. If another place enters a
3117 * drain section for the same parent, but wants it to be fully quiesced, it
3118 * will not run most of the the code in .drained_begin() again (which is not
3119 * a problem, we already did this), but it will still poll until the parent
3120 * is fully quiesced, so it will not be negatively affected either.
3122 bdrv_parent_drained_begin_single(new_child);
3123 bdrv_replace_child_noperm(new_child, child_bs);
3125 BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
3126 *s = (BdrvAttachChildCommonState) {
3127 .child = new_child,
3128 .old_parent_ctx = parent_ctx,
3129 .old_child_ctx = child_ctx,
3131 tran_add(tran, &bdrv_attach_child_common_drv, s);
3133 if (new_child_ctx != child_ctx) {
3134 aio_context_release(new_child_ctx);
3135 aio_context_acquire(child_ctx);
3138 return new_child;
3142 * Function doesn't update permissions, caller is responsible for this.
3144 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
3145 * @child_bs can move to a different AioContext in this function. Callers must
3146 * make sure that their AioContext locking is still correct after this.
3148 * After calling this function, the transaction @tran may only be completed
3149 * while holding a writer lock for the graph.
3151 static BdrvChild * GRAPH_WRLOCK
3152 bdrv_attach_child_noperm(BlockDriverState *parent_bs,
3153 BlockDriverState *child_bs,
3154 const char *child_name,
3155 const BdrvChildClass *child_class,
3156 BdrvChildRole child_role,
3157 Transaction *tran,
3158 Error **errp)
3160 uint64_t perm, shared_perm;
3162 assert(parent_bs->drv);
3163 GLOBAL_STATE_CODE();
3165 if (bdrv_recurse_has_child(child_bs, parent_bs)) {
3166 error_setg(errp, "Making '%s' a %s child of '%s' would create a cycle",
3167 child_bs->node_name, child_name, parent_bs->node_name);
3168 return NULL;
3171 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
3172 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
3173 perm, shared_perm, &perm, &shared_perm);
3175 return bdrv_attach_child_common(child_bs, child_name, child_class,
3176 child_role, perm, shared_perm, parent_bs,
3177 tran, errp);
3181 * This function steals the reference to child_bs from the caller.
3182 * That reference is later dropped by bdrv_root_unref_child().
3184 * On failure NULL is returned, errp is set and the reference to
3185 * child_bs is also dropped.
3187 * The caller must hold the AioContext lock @child_bs, but not that of @ctx
3188 * (unless @child_bs is already in @ctx).
3190 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
3191 const char *child_name,
3192 const BdrvChildClass *child_class,
3193 BdrvChildRole child_role,
3194 uint64_t perm, uint64_t shared_perm,
3195 void *opaque, Error **errp)
3197 int ret;
3198 BdrvChild *child;
3199 Transaction *tran = tran_new();
3201 GLOBAL_STATE_CODE();
3203 bdrv_graph_wrlock(child_bs);
3205 child = bdrv_attach_child_common(child_bs, child_name, child_class,
3206 child_role, perm, shared_perm, opaque,
3207 tran, errp);
3208 if (!child) {
3209 ret = -EINVAL;
3210 goto out;
3213 ret = bdrv_refresh_perms(child_bs, tran, errp);
3215 out:
3216 tran_finalize(tran, ret);
3217 bdrv_graph_wrunlock();
3219 bdrv_unref(child_bs);
3221 return ret < 0 ? NULL : child;
3225 * This function transfers the reference to child_bs from the caller
3226 * to parent_bs. That reference is later dropped by parent_bs on
3227 * bdrv_close() or if someone calls bdrv_unref_child().
3229 * On failure NULL is returned, errp is set and the reference to
3230 * child_bs is also dropped.
3232 * If @parent_bs and @child_bs are in different AioContexts, the caller must
3233 * hold the AioContext lock for @child_bs, but not for @parent_bs.
3235 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
3236 BlockDriverState *child_bs,
3237 const char *child_name,
3238 const BdrvChildClass *child_class,
3239 BdrvChildRole child_role,
3240 Error **errp)
3242 int ret;
3243 BdrvChild *child;
3244 Transaction *tran = tran_new();
3246 GLOBAL_STATE_CODE();
3248 child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name,
3249 child_class, child_role, tran, errp);
3250 if (!child) {
3251 ret = -EINVAL;
3252 goto out;
3255 ret = bdrv_refresh_perms(parent_bs, tran, errp);
3256 if (ret < 0) {
3257 goto out;
3260 out:
3261 tran_finalize(tran, ret);
3263 bdrv_schedule_unref(child_bs);
3265 return ret < 0 ? NULL : child;
3268 /* Callers must ensure that child->frozen is false. */
3269 void bdrv_root_unref_child(BdrvChild *child)
3271 BlockDriverState *child_bs = child->bs;
3273 GLOBAL_STATE_CODE();
3274 bdrv_replace_child_noperm(child, NULL);
3275 bdrv_child_free(child);
3277 if (child_bs) {
3279 * Update permissions for old node. We're just taking a parent away, so
3280 * we're loosening restrictions. Errors of permission update are not
3281 * fatal in this case, ignore them.
3283 bdrv_refresh_perms(child_bs, NULL, NULL);
3286 * When the parent requiring a non-default AioContext is removed, the
3287 * node moves back to the main AioContext
3289 bdrv_try_change_aio_context(child_bs, qemu_get_aio_context(), NULL,
3290 NULL);
3293 bdrv_schedule_unref(child_bs);
3296 typedef struct BdrvSetInheritsFrom {
3297 BlockDriverState *bs;
3298 BlockDriverState *old_inherits_from;
3299 } BdrvSetInheritsFrom;
3301 static void bdrv_set_inherits_from_abort(void *opaque)
3303 BdrvSetInheritsFrom *s = opaque;
3305 s->bs->inherits_from = s->old_inherits_from;
3308 static TransactionActionDrv bdrv_set_inherits_from_drv = {
3309 .abort = bdrv_set_inherits_from_abort,
3310 .clean = g_free,
3313 /* @tran is allowed to be NULL. In this case no rollback is possible */
3314 static void bdrv_set_inherits_from(BlockDriverState *bs,
3315 BlockDriverState *new_inherits_from,
3316 Transaction *tran)
3318 if (tran) {
3319 BdrvSetInheritsFrom *s = g_new(BdrvSetInheritsFrom, 1);
3321 *s = (BdrvSetInheritsFrom) {
3322 .bs = bs,
3323 .old_inherits_from = bs->inherits_from,
3326 tran_add(tran, &bdrv_set_inherits_from_drv, s);
3329 bs->inherits_from = new_inherits_from;
3333 * Clear all inherits_from pointers from children and grandchildren of
3334 * @root that point to @root, where necessary.
3335 * @tran is allowed to be NULL. In this case no rollback is possible
3337 static void GRAPH_WRLOCK
3338 bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child,
3339 Transaction *tran)
3341 BdrvChild *c;
3343 if (child->bs->inherits_from == root) {
3345 * Remove inherits_from only when the last reference between root and
3346 * child->bs goes away.
3348 QLIST_FOREACH(c, &root->children, next) {
3349 if (c != child && c->bs == child->bs) {
3350 break;
3353 if (c == NULL) {
3354 bdrv_set_inherits_from(child->bs, NULL, tran);
3358 QLIST_FOREACH(c, &child->bs->children, next) {
3359 bdrv_unset_inherits_from(root, c, tran);
3363 /* Callers must ensure that child->frozen is false. */
3364 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
3366 GLOBAL_STATE_CODE();
3367 if (child == NULL) {
3368 return;
3371 bdrv_unset_inherits_from(parent, child, NULL);
3372 bdrv_root_unref_child(child);
3376 static void GRAPH_RDLOCK
3377 bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
3379 BdrvChild *c;
3380 GLOBAL_STATE_CODE();
3381 QLIST_FOREACH(c, &bs->parents, next_parent) {
3382 if (c->klass->change_media) {
3383 c->klass->change_media(c, load);
3388 /* Return true if you can reach parent going through child->inherits_from
3389 * recursively. If parent or child are NULL, return false */
3390 static bool bdrv_inherits_from_recursive(BlockDriverState *child,
3391 BlockDriverState *parent)
3393 while (child && child != parent) {
3394 child = child->inherits_from;
3397 return child != NULL;
3401 * Return the BdrvChildRole for @bs's backing child. bs->backing is
3402 * mostly used for COW backing children (role = COW), but also for
3403 * filtered children (role = FILTERED | PRIMARY).
3405 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
3407 if (bs->drv && bs->drv->is_filter) {
3408 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
3409 } else {
3410 return BDRV_CHILD_COW;
3415 * Sets the bs->backing or bs->file link of a BDS. A new reference is created;
3416 * callers which don't need their own reference any more must call bdrv_unref().
3418 * If the respective child is already present (i.e. we're detaching a node),
3419 * that child node must be drained.
3421 * Function doesn't update permissions, caller is responsible for this.
3423 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
3424 * @child_bs can move to a different AioContext in this function. Callers must
3425 * make sure that their AioContext locking is still correct after this.
3427 * After calling this function, the transaction @tran may only be completed
3428 * while holding a writer lock for the graph.
3430 static int GRAPH_WRLOCK
3431 bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
3432 BlockDriverState *child_bs,
3433 bool is_backing,
3434 Transaction *tran, Error **errp)
3436 bool update_inherits_from =
3437 bdrv_inherits_from_recursive(child_bs, parent_bs);
3438 BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file;
3439 BdrvChildRole role;
3441 GLOBAL_STATE_CODE();
3443 if (!parent_bs->drv) {
3445 * Node without drv is an object without a class :/. TODO: finally fix
3446 * qcow2 driver to never clear bs->drv and implement format corruption
3447 * handling in other way.
3449 error_setg(errp, "Node corrupted");
3450 return -EINVAL;
3453 if (child && child->frozen) {
3454 error_setg(errp, "Cannot change frozen '%s' link from '%s' to '%s'",
3455 child->name, parent_bs->node_name, child->bs->node_name);
3456 return -EPERM;
3459 if (is_backing && !parent_bs->drv->is_filter &&
3460 !parent_bs->drv->supports_backing)
3462 error_setg(errp, "Driver '%s' of node '%s' does not support backing "
3463 "files", parent_bs->drv->format_name, parent_bs->node_name);
3464 return -EINVAL;
3467 if (parent_bs->drv->is_filter) {
3468 role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
3469 } else if (is_backing) {
3470 role = BDRV_CHILD_COW;
3471 } else {
3473 * We only can use same role as it is in existing child. We don't have
3474 * infrastructure to determine role of file child in generic way
3476 if (!child) {
3477 error_setg(errp, "Cannot set file child to format node without "
3478 "file child");
3479 return -EINVAL;
3481 role = child->role;
3484 if (child) {
3485 assert(child->bs->quiesce_counter);
3486 bdrv_unset_inherits_from(parent_bs, child, tran);
3487 bdrv_remove_child(child, tran);
3490 if (!child_bs) {
3491 goto out;
3494 child = bdrv_attach_child_noperm(parent_bs, child_bs,
3495 is_backing ? "backing" : "file",
3496 &child_of_bds, role,
3497 tran, errp);
3498 if (!child) {
3499 return -EINVAL;
3504 * If inherits_from pointed recursively to bs then let's update it to
3505 * point directly to bs (else it will become NULL).
3507 if (update_inherits_from) {
3508 bdrv_set_inherits_from(child_bs, parent_bs, tran);
3511 out:
3512 bdrv_refresh_limits(parent_bs, tran, NULL);
3514 return 0;
3518 * The caller must hold the AioContext lock for @backing_hd. Both @bs and
3519 * @backing_hd can move to a different AioContext in this function. Callers must
3520 * make sure that their AioContext locking is still correct after this.
3522 * If a backing child is already present (i.e. we're detaching a node), that
3523 * child node must be drained.
3525 * After calling this function, the transaction @tran may only be completed
3526 * while holding a writer lock for the graph.
3528 static int GRAPH_WRLOCK
3529 bdrv_set_backing_noperm(BlockDriverState *bs,
3530 BlockDriverState *backing_hd,
3531 Transaction *tran, Error **errp)
3533 GLOBAL_STATE_CODE();
3534 return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp);
3537 int bdrv_set_backing_hd_drained(BlockDriverState *bs,
3538 BlockDriverState *backing_hd,
3539 Error **errp)
3541 int ret;
3542 Transaction *tran = tran_new();
3544 GLOBAL_STATE_CODE();
3545 assert(bs->quiesce_counter > 0);
3546 if (bs->backing) {
3547 assert(bs->backing->bs->quiesce_counter > 0);
3549 bdrv_graph_wrlock(backing_hd);
3551 ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
3552 if (ret < 0) {
3553 goto out;
3556 ret = bdrv_refresh_perms(bs, tran, errp);
3557 out:
3558 tran_finalize(tran, ret);
3559 bdrv_graph_wrunlock();
3560 return ret;
3563 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
3564 Error **errp)
3566 BlockDriverState *drain_bs = bs->backing ? bs->backing->bs : bs;
3567 int ret;
3568 GLOBAL_STATE_CODE();
3570 bdrv_ref(drain_bs);
3571 bdrv_drained_begin(drain_bs);
3572 ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp);
3573 bdrv_drained_end(drain_bs);
3574 bdrv_unref(drain_bs);
3576 return ret;
3580 * Opens the backing file for a BlockDriverState if not yet open
3582 * bdref_key specifies the key for the image's BlockdevRef in the options QDict.
3583 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3584 * itself, all options starting with "${bdref_key}." are considered part of the
3585 * BlockdevRef.
3587 * The caller must hold the main AioContext lock.
3589 * TODO Can this be unified with bdrv_open_image()?
3591 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
3592 const char *bdref_key, Error **errp)
3594 char *backing_filename = NULL;
3595 char *bdref_key_dot;
3596 const char *reference = NULL;
3597 int ret = 0;
3598 bool implicit_backing = false;
3599 BlockDriverState *backing_hd;
3600 AioContext *backing_hd_ctx;
3601 QDict *options;
3602 QDict *tmp_parent_options = NULL;
3603 Error *local_err = NULL;
3605 GLOBAL_STATE_CODE();
3607 if (bs->backing != NULL) {
3608 goto free_exit;
3611 /* NULL means an empty set of options */
3612 if (parent_options == NULL) {
3613 tmp_parent_options = qdict_new();
3614 parent_options = tmp_parent_options;
3617 bs->open_flags &= ~BDRV_O_NO_BACKING;
3619 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3620 qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
3621 g_free(bdref_key_dot);
3624 * Caution: while qdict_get_try_str() is fine, getting non-string
3625 * types would require more care. When @parent_options come from
3626 * -blockdev or blockdev_add, its members are typed according to
3627 * the QAPI schema, but when they come from -drive, they're all
3628 * QString.
3630 reference = qdict_get_try_str(parent_options, bdref_key);
3631 if (reference || qdict_haskey(options, "file.filename")) {
3632 /* keep backing_filename NULL */
3633 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
3634 qobject_unref(options);
3635 goto free_exit;
3636 } else {
3637 if (qdict_size(options) == 0) {
3638 /* If the user specifies options that do not modify the
3639 * backing file's behavior, we might still consider it the
3640 * implicit backing file. But it's easier this way, and
3641 * just specifying some of the backing BDS's options is
3642 * only possible with -drive anyway (otherwise the QAPI
3643 * schema forces the user to specify everything). */
3644 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
3647 backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
3648 if (local_err) {
3649 ret = -EINVAL;
3650 error_propagate(errp, local_err);
3651 qobject_unref(options);
3652 goto free_exit;
3656 if (!bs->drv || !bs->drv->supports_backing) {
3657 ret = -EINVAL;
3658 error_setg(errp, "Driver doesn't support backing files");
3659 qobject_unref(options);
3660 goto free_exit;
3663 if (!reference &&
3664 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
3665 qdict_put_str(options, "driver", bs->backing_format);
3668 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
3669 &child_of_bds, bdrv_backing_role(bs), errp);
3670 if (!backing_hd) {
3671 bs->open_flags |= BDRV_O_NO_BACKING;
3672 error_prepend(errp, "Could not open backing file: ");
3673 ret = -EINVAL;
3674 goto free_exit;
3677 if (implicit_backing) {
3678 bdrv_refresh_filename(backing_hd);
3679 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
3680 backing_hd->filename);
3683 /* Hook up the backing file link; drop our reference, bs owns the
3684 * backing_hd reference now */
3685 backing_hd_ctx = bdrv_get_aio_context(backing_hd);
3686 aio_context_acquire(backing_hd_ctx);
3687 ret = bdrv_set_backing_hd(bs, backing_hd, errp);
3688 bdrv_unref(backing_hd);
3689 aio_context_release(backing_hd_ctx);
3691 if (ret < 0) {
3692 goto free_exit;
3695 qdict_del(parent_options, bdref_key);
3697 free_exit:
3698 g_free(backing_filename);
3699 qobject_unref(tmp_parent_options);
3700 return ret;
3703 static BlockDriverState *
3704 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
3705 BlockDriverState *parent, const BdrvChildClass *child_class,
3706 BdrvChildRole child_role, bool allow_none, Error **errp)
3708 BlockDriverState *bs = NULL;
3709 QDict *image_options;
3710 char *bdref_key_dot;
3711 const char *reference;
3713 assert(child_class != NULL);
3715 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3716 qdict_extract_subqdict(options, &image_options, bdref_key_dot);
3717 g_free(bdref_key_dot);
3720 * Caution: while qdict_get_try_str() is fine, getting non-string
3721 * types would require more care. When @options come from
3722 * -blockdev or blockdev_add, its members are typed according to
3723 * the QAPI schema, but when they come from -drive, they're all
3724 * QString.
3726 reference = qdict_get_try_str(options, bdref_key);
3727 if (!filename && !reference && !qdict_size(image_options)) {
3728 if (!allow_none) {
3729 error_setg(errp, "A block device must be specified for \"%s\"",
3730 bdref_key);
3732 qobject_unref(image_options);
3733 goto done;
3736 bs = bdrv_open_inherit(filename, reference, image_options, 0,
3737 parent, child_class, child_role, errp);
3738 if (!bs) {
3739 goto done;
3742 done:
3743 qdict_del(options, bdref_key);
3744 return bs;
3748 * Opens a disk image whose options are given as BlockdevRef in another block
3749 * device's options.
3751 * If allow_none is true, no image will be opened if filename is false and no
3752 * BlockdevRef is given. NULL will be returned, but errp remains unset.
3754 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
3755 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3756 * itself, all options starting with "${bdref_key}." are considered part of the
3757 * BlockdevRef.
3759 * The BlockdevRef will be removed from the options QDict.
3761 * The caller must hold the lock of the main AioContext and no other AioContext.
3762 * @parent can move to a different AioContext in this function. Callers must
3763 * make sure that their AioContext locking is still correct after this.
3765 BdrvChild *bdrv_open_child(const char *filename,
3766 QDict *options, const char *bdref_key,
3767 BlockDriverState *parent,
3768 const BdrvChildClass *child_class,
3769 BdrvChildRole child_role,
3770 bool allow_none, Error **errp)
3772 BlockDriverState *bs;
3773 BdrvChild *child;
3774 AioContext *ctx;
3776 GLOBAL_STATE_CODE();
3778 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
3779 child_role, allow_none, errp);
3780 if (bs == NULL) {
3781 return NULL;
3784 bdrv_graph_wrlock(NULL);
3785 ctx = bdrv_get_aio_context(bs);
3786 aio_context_acquire(ctx);
3787 child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
3788 errp);
3789 aio_context_release(ctx);
3790 bdrv_graph_wrunlock();
3792 return child;
3796 * Wrapper on bdrv_open_child() for most popular case: open primary child of bs.
3798 * The caller must hold the lock of the main AioContext and no other AioContext.
3799 * @parent can move to a different AioContext in this function. Callers must
3800 * make sure that their AioContext locking is still correct after this.
3802 int bdrv_open_file_child(const char *filename,
3803 QDict *options, const char *bdref_key,
3804 BlockDriverState *parent, Error **errp)
3806 BdrvChildRole role;
3808 /* commit_top and mirror_top don't use this function */
3809 assert(!parent->drv->filtered_child_is_backing);
3810 role = parent->drv->is_filter ?
3811 (BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE;
3813 if (!bdrv_open_child(filename, options, bdref_key, parent,
3814 &child_of_bds, role, false, errp))
3816 return -EINVAL;
3819 return 0;
3823 * TODO Future callers may need to specify parent/child_class in order for
3824 * option inheritance to work. Existing callers use it for the root node.
3826 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
3828 BlockDriverState *bs = NULL;
3829 QObject *obj = NULL;
3830 QDict *qdict = NULL;
3831 const char *reference = NULL;
3832 Visitor *v = NULL;
3834 GLOBAL_STATE_CODE();
3836 if (ref->type == QTYPE_QSTRING) {
3837 reference = ref->u.reference;
3838 } else {
3839 BlockdevOptions *options = &ref->u.definition;
3840 assert(ref->type == QTYPE_QDICT);
3842 v = qobject_output_visitor_new(&obj);
3843 visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
3844 visit_complete(v, &obj);
3846 qdict = qobject_to(QDict, obj);
3847 qdict_flatten(qdict);
3849 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for
3850 * compatibility with other callers) rather than what we want as the
3851 * real defaults. Apply the defaults here instead. */
3852 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
3853 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
3854 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
3855 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
3859 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp);
3860 obj = NULL;
3861 qobject_unref(obj);
3862 visit_free(v);
3863 return bs;
3866 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
3867 int flags,
3868 QDict *snapshot_options,
3869 Error **errp)
3871 g_autofree char *tmp_filename = NULL;
3872 int64_t total_size;
3873 QemuOpts *opts = NULL;
3874 BlockDriverState *bs_snapshot = NULL;
3875 AioContext *ctx = bdrv_get_aio_context(bs);
3876 int ret;
3878 GLOBAL_STATE_CODE();
3880 /* if snapshot, we create a temporary backing file and open it
3881 instead of opening 'filename' directly */
3883 /* Get the required size from the image */
3884 aio_context_acquire(ctx);
3885 total_size = bdrv_getlength(bs);
3886 aio_context_release(ctx);
3888 if (total_size < 0) {
3889 error_setg_errno(errp, -total_size, "Could not get image size");
3890 goto out;
3893 /* Create the temporary image */
3894 tmp_filename = create_tmp_file(errp);
3895 if (!tmp_filename) {
3896 goto out;
3899 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
3900 &error_abort);
3901 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
3902 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
3903 qemu_opts_del(opts);
3904 if (ret < 0) {
3905 error_prepend(errp, "Could not create temporary overlay '%s': ",
3906 tmp_filename);
3907 goto out;
3910 /* Prepare options QDict for the temporary file */
3911 qdict_put_str(snapshot_options, "file.driver", "file");
3912 qdict_put_str(snapshot_options, "file.filename", tmp_filename);
3913 qdict_put_str(snapshot_options, "driver", "qcow2");
3915 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
3916 snapshot_options = NULL;
3917 if (!bs_snapshot) {
3918 goto out;
3921 aio_context_acquire(ctx);
3922 ret = bdrv_append(bs_snapshot, bs, errp);
3923 aio_context_release(ctx);
3925 if (ret < 0) {
3926 bs_snapshot = NULL;
3927 goto out;
3930 out:
3931 qobject_unref(snapshot_options);
3932 return bs_snapshot;
3936 * Opens a disk image (raw, qcow2, vmdk, ...)
3938 * options is a QDict of options to pass to the block drivers, or NULL for an
3939 * empty set of options. The reference to the QDict belongs to the block layer
3940 * after the call (even on failure), so if the caller intends to reuse the
3941 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
3943 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
3944 * If it is not NULL, the referenced BDS will be reused.
3946 * The reference parameter may be used to specify an existing block device which
3947 * should be opened. If specified, neither options nor a filename may be given,
3948 * nor can an existing BDS be reused (that is, *pbs has to be NULL).
3950 * The caller must always hold the main AioContext lock.
3952 static BlockDriverState * no_coroutine_fn
3953 bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
3954 int flags, BlockDriverState *parent,
3955 const BdrvChildClass *child_class, BdrvChildRole child_role,
3956 Error **errp)
3958 int ret;
3959 BlockBackend *file = NULL;
3960 BlockDriverState *bs;
3961 BlockDriver *drv = NULL;
3962 BdrvChild *child;
3963 const char *drvname;
3964 const char *backing;
3965 Error *local_err = NULL;
3966 QDict *snapshot_options = NULL;
3967 int snapshot_flags = 0;
3968 AioContext *ctx = qemu_get_aio_context();
3970 assert(!child_class || !flags);
3971 assert(!child_class == !parent);
3972 GLOBAL_STATE_CODE();
3973 assert(!qemu_in_coroutine());
3975 /* TODO We'll eventually have to take a writer lock in this function */
3976 GRAPH_RDLOCK_GUARD_MAINLOOP();
3978 if (reference) {
3979 bool options_non_empty = options ? qdict_size(options) : false;
3980 qobject_unref(options);
3982 if (filename || options_non_empty) {
3983 error_setg(errp, "Cannot reference an existing block device with "
3984 "additional options or a new filename");
3985 return NULL;
3988 bs = bdrv_lookup_bs(reference, reference, errp);
3989 if (!bs) {
3990 return NULL;
3993 bdrv_ref(bs);
3994 return bs;
3997 bs = bdrv_new();
3999 /* NULL means an empty set of options */
4000 if (options == NULL) {
4001 options = qdict_new();
4004 /* json: syntax counts as explicit options, as if in the QDict */
4005 parse_json_protocol(options, &filename, &local_err);
4006 if (local_err) {
4007 goto fail;
4010 bs->explicit_options = qdict_clone_shallow(options);
4012 if (child_class) {
4013 bool parent_is_format;
4015 if (parent->drv) {
4016 parent_is_format = parent->drv->is_format;
4017 } else {
4019 * parent->drv is not set yet because this node is opened for
4020 * (potential) format probing. That means that @parent is going
4021 * to be a format node.
4023 parent_is_format = true;
4026 bs->inherits_from = parent;
4027 child_class->inherit_options(child_role, parent_is_format,
4028 &flags, options,
4029 parent->open_flags, parent->options);
4032 ret = bdrv_fill_options(&options, filename, &flags, &local_err);
4033 if (ret < 0) {
4034 goto fail;
4038 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
4039 * Caution: getting a boolean member of @options requires care.
4040 * When @options come from -blockdev or blockdev_add, members are
4041 * typed according to the QAPI schema, but when they come from
4042 * -drive, they're all QString.
4044 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
4045 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
4046 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
4047 } else {
4048 flags &= ~BDRV_O_RDWR;
4051 if (flags & BDRV_O_SNAPSHOT) {
4052 snapshot_options = qdict_new();
4053 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options,
4054 flags, options);
4055 /* Let bdrv_backing_options() override "read-only" */
4056 qdict_del(options, BDRV_OPT_READ_ONLY);
4057 bdrv_inherited_options(BDRV_CHILD_COW, true,
4058 &flags, options, flags, options);
4061 bs->open_flags = flags;
4062 bs->options = options;
4063 options = qdict_clone_shallow(options);
4065 /* Find the right image format driver */
4066 /* See cautionary note on accessing @options above */
4067 drvname = qdict_get_try_str(options, "driver");
4068 if (drvname) {
4069 drv = bdrv_find_format(drvname);
4070 if (!drv) {
4071 error_setg(errp, "Unknown driver: '%s'", drvname);
4072 goto fail;
4076 assert(drvname || !(flags & BDRV_O_PROTOCOL));
4078 /* See cautionary note on accessing @options above */
4079 backing = qdict_get_try_str(options, "backing");
4080 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
4081 (backing && *backing == '\0'))
4083 if (backing) {
4084 warn_report("Use of \"backing\": \"\" is deprecated; "
4085 "use \"backing\": null instead");
4087 flags |= BDRV_O_NO_BACKING;
4088 qdict_del(bs->explicit_options, "backing");
4089 qdict_del(bs->options, "backing");
4090 qdict_del(options, "backing");
4093 /* Open image file without format layer. This BlockBackend is only used for
4094 * probing, the block drivers will do their own bdrv_open_child() for the
4095 * same BDS, which is why we put the node name back into options. */
4096 if ((flags & BDRV_O_PROTOCOL) == 0) {
4097 BlockDriverState *file_bs;
4099 file_bs = bdrv_open_child_bs(filename, options, "file", bs,
4100 &child_of_bds, BDRV_CHILD_IMAGE,
4101 true, &local_err);
4102 if (local_err) {
4103 goto fail;
4105 if (file_bs != NULL) {
4106 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only
4107 * looking at the header to guess the image format. This works even
4108 * in cases where a guest would not see a consistent state. */
4109 ctx = bdrv_get_aio_context(file_bs);
4110 aio_context_acquire(ctx);
4111 file = blk_new(ctx, 0, BLK_PERM_ALL);
4112 blk_insert_bs(file, file_bs, &local_err);
4113 bdrv_unref(file_bs);
4114 aio_context_release(ctx);
4116 if (local_err) {
4117 goto fail;
4120 qdict_put_str(options, "file", bdrv_get_node_name(file_bs));
4124 /* Image format probing */
4125 bs->probed = !drv;
4126 if (!drv && file) {
4127 ret = find_image_format(file, filename, &drv, &local_err);
4128 if (ret < 0) {
4129 goto fail;
4132 * This option update would logically belong in bdrv_fill_options(),
4133 * but we first need to open bs->file for the probing to work, while
4134 * opening bs->file already requires the (mostly) final set of options
4135 * so that cache mode etc. can be inherited.
4137 * Adding the driver later is somewhat ugly, but it's not an option
4138 * that would ever be inherited, so it's correct. We just need to make
4139 * sure to update both bs->options (which has the full effective
4140 * options for bs) and options (which has file.* already removed).
4142 qdict_put_str(bs->options, "driver", drv->format_name);
4143 qdict_put_str(options, "driver", drv->format_name);
4144 } else if (!drv) {
4145 error_setg(errp, "Must specify either driver or file");
4146 goto fail;
4149 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
4150 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
4151 /* file must be NULL if a protocol BDS is about to be created
4152 * (the inverse results in an error message from bdrv_open_common()) */
4153 assert(!(flags & BDRV_O_PROTOCOL) || !file);
4155 /* Open the image */
4156 ret = bdrv_open_common(bs, file, options, &local_err);
4157 if (ret < 0) {
4158 goto fail;
4161 /* The AioContext could have changed during bdrv_open_common() */
4162 ctx = bdrv_get_aio_context(bs);
4164 if (file) {
4165 aio_context_acquire(ctx);
4166 blk_unref(file);
4167 aio_context_release(ctx);
4168 file = NULL;
4171 /* If there is a backing file, use it */
4172 if ((flags & BDRV_O_NO_BACKING) == 0) {
4173 ret = bdrv_open_backing_file(bs, options, "backing", &local_err);
4174 if (ret < 0) {
4175 goto close_and_fail;
4179 /* Remove all children options and references
4180 * from bs->options and bs->explicit_options */
4181 QLIST_FOREACH(child, &bs->children, next) {
4182 char *child_key_dot;
4183 child_key_dot = g_strdup_printf("%s.", child->name);
4184 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot);
4185 qdict_extract_subqdict(bs->options, NULL, child_key_dot);
4186 qdict_del(bs->explicit_options, child->name);
4187 qdict_del(bs->options, child->name);
4188 g_free(child_key_dot);
4191 /* Check if any unknown options were used */
4192 if (qdict_size(options) != 0) {
4193 const QDictEntry *entry = qdict_first(options);
4194 if (flags & BDRV_O_PROTOCOL) {
4195 error_setg(errp, "Block protocol '%s' doesn't support the option "
4196 "'%s'", drv->format_name, entry->key);
4197 } else {
4198 error_setg(errp,
4199 "Block format '%s' does not support the option '%s'",
4200 drv->format_name, entry->key);
4203 goto close_and_fail;
4206 bdrv_parent_cb_change_media(bs, true);
4208 qobject_unref(options);
4209 options = NULL;
4211 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
4212 * temporary snapshot afterwards. */
4213 if (snapshot_flags) {
4214 BlockDriverState *snapshot_bs;
4215 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags,
4216 snapshot_options, &local_err);
4217 snapshot_options = NULL;
4218 if (local_err) {
4219 goto close_and_fail;
4221 /* We are not going to return bs but the overlay on top of it
4222 * (snapshot_bs); thus, we have to drop the strong reference to bs
4223 * (which we obtained by calling bdrv_new()). bs will not be deleted,
4224 * though, because the overlay still has a reference to it. */
4225 aio_context_acquire(ctx);
4226 bdrv_unref(bs);
4227 aio_context_release(ctx);
4228 bs = snapshot_bs;
4231 return bs;
4233 fail:
4234 aio_context_acquire(ctx);
4235 blk_unref(file);
4236 qobject_unref(snapshot_options);
4237 qobject_unref(bs->explicit_options);
4238 qobject_unref(bs->options);
4239 qobject_unref(options);
4240 bs->options = NULL;
4241 bs->explicit_options = NULL;
4242 bdrv_unref(bs);
4243 aio_context_release(ctx);
4244 error_propagate(errp, local_err);
4245 return NULL;
4247 close_and_fail:
4248 aio_context_acquire(ctx);
4249 bdrv_unref(bs);
4250 aio_context_release(ctx);
4251 qobject_unref(snapshot_options);
4252 qobject_unref(options);
4253 error_propagate(errp, local_err);
4254 return NULL;
4257 /* The caller must always hold the main AioContext lock. */
4258 BlockDriverState *bdrv_open(const char *filename, const char *reference,
4259 QDict *options, int flags, Error **errp)
4261 GLOBAL_STATE_CODE();
4263 return bdrv_open_inherit(filename, reference, options, flags, NULL,
4264 NULL, 0, errp);
4267 /* Return true if the NULL-terminated @list contains @str */
4268 static bool is_str_in_list(const char *str, const char *const *list)
4270 if (str && list) {
4271 int i;
4272 for (i = 0; list[i] != NULL; i++) {
4273 if (!strcmp(str, list[i])) {
4274 return true;
4278 return false;
4282 * Check that every option set in @bs->options is also set in
4283 * @new_opts.
4285 * Options listed in the common_options list and in
4286 * @bs->drv->mutable_opts are skipped.
4288 * Return 0 on success, otherwise return -EINVAL and set @errp.
4290 static int bdrv_reset_options_allowed(BlockDriverState *bs,
4291 const QDict *new_opts, Error **errp)
4293 const QDictEntry *e;
4294 /* These options are common to all block drivers and are handled
4295 * in bdrv_reopen_prepare() so they can be left out of @new_opts */
4296 const char *const common_options[] = {
4297 "node-name", "discard", "cache.direct", "cache.no-flush",
4298 "read-only", "auto-read-only", "detect-zeroes", NULL
4301 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) {
4302 if (!qdict_haskey(new_opts, e->key) &&
4303 !is_str_in_list(e->key, common_options) &&
4304 !is_str_in_list(e->key, bs->drv->mutable_opts)) {
4305 error_setg(errp, "Option '%s' cannot be reset "
4306 "to its default value", e->key);
4307 return -EINVAL;
4311 return 0;
4315 * Returns true if @child can be reached recursively from @bs
4317 static bool bdrv_recurse_has_child(BlockDriverState *bs,
4318 BlockDriverState *child)
4320 BdrvChild *c;
4322 if (bs == child) {
4323 return true;
4326 QLIST_FOREACH(c, &bs->children, next) {
4327 if (bdrv_recurse_has_child(c->bs, child)) {
4328 return true;
4332 return false;
4336 * Adds a BlockDriverState to a simple queue for an atomic, transactional
4337 * reopen of multiple devices.
4339 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT
4340 * already performed, or alternatively may be NULL a new BlockReopenQueue will
4341 * be created and initialized. This newly created BlockReopenQueue should be
4342 * passed back in for subsequent calls that are intended to be of the same
4343 * atomic 'set'.
4345 * bs is the BlockDriverState to add to the reopen queue.
4347 * options contains the changed options for the associated bs
4348 * (the BlockReopenQueue takes ownership)
4350 * flags contains the open flags for the associated bs
4352 * returns a pointer to bs_queue, which is either the newly allocated
4353 * bs_queue, or the existing bs_queue being used.
4355 * bs is drained here and undrained by bdrv_reopen_queue_free().
4357 * To be called with bs->aio_context locked.
4359 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
4360 BlockDriverState *bs,
4361 QDict *options,
4362 const BdrvChildClass *klass,
4363 BdrvChildRole role,
4364 bool parent_is_format,
4365 QDict *parent_options,
4366 int parent_flags,
4367 bool keep_old_opts)
4369 assert(bs != NULL);
4371 BlockReopenQueueEntry *bs_entry;
4372 BdrvChild *child;
4373 QDict *old_options, *explicit_options, *options_copy;
4374 int flags;
4375 QemuOpts *opts;
4377 GLOBAL_STATE_CODE();
4379 bdrv_drained_begin(bs);
4381 if (bs_queue == NULL) {
4382 bs_queue = g_new0(BlockReopenQueue, 1);
4383 QTAILQ_INIT(bs_queue);
4386 if (!options) {
4387 options = qdict_new();
4390 /* Check if this BlockDriverState is already in the queue */
4391 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4392 if (bs == bs_entry->state.bs) {
4393 break;
4398 * Precedence of options:
4399 * 1. Explicitly passed in options (highest)
4400 * 2. Retained from explicitly set options of bs
4401 * 3. Inherited from parent node
4402 * 4. Retained from effective options of bs
4405 /* Old explicitly set values (don't overwrite by inherited value) */
4406 if (bs_entry || keep_old_opts) {
4407 old_options = qdict_clone_shallow(bs_entry ?
4408 bs_entry->state.explicit_options :
4409 bs->explicit_options);
4410 bdrv_join_options(bs, options, old_options);
4411 qobject_unref(old_options);
4414 explicit_options = qdict_clone_shallow(options);
4416 /* Inherit from parent node */
4417 if (parent_options) {
4418 flags = 0;
4419 klass->inherit_options(role, parent_is_format, &flags, options,
4420 parent_flags, parent_options);
4421 } else {
4422 flags = bdrv_get_flags(bs);
4425 if (keep_old_opts) {
4426 /* Old values are used for options that aren't set yet */
4427 old_options = qdict_clone_shallow(bs->options);
4428 bdrv_join_options(bs, options, old_options);
4429 qobject_unref(old_options);
4432 /* We have the final set of options so let's update the flags */
4433 options_copy = qdict_clone_shallow(options);
4434 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4435 qemu_opts_absorb_qdict(opts, options_copy, NULL);
4436 update_flags_from_options(&flags, opts);
4437 qemu_opts_del(opts);
4438 qobject_unref(options_copy);
4440 /* bdrv_open_inherit() sets and clears some additional flags internally */
4441 flags &= ~BDRV_O_PROTOCOL;
4442 if (flags & BDRV_O_RDWR) {
4443 flags |= BDRV_O_ALLOW_RDWR;
4446 if (!bs_entry) {
4447 bs_entry = g_new0(BlockReopenQueueEntry, 1);
4448 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry);
4449 } else {
4450 qobject_unref(bs_entry->state.options);
4451 qobject_unref(bs_entry->state.explicit_options);
4454 bs_entry->state.bs = bs;
4455 bs_entry->state.options = options;
4456 bs_entry->state.explicit_options = explicit_options;
4457 bs_entry->state.flags = flags;
4460 * If keep_old_opts is false then it means that unspecified
4461 * options must be reset to their original value. We don't allow
4462 * resetting 'backing' but we need to know if the option is
4463 * missing in order to decide if we have to return an error.
4465 if (!keep_old_opts) {
4466 bs_entry->state.backing_missing =
4467 !qdict_haskey(options, "backing") &&
4468 !qdict_haskey(options, "backing.driver");
4471 QLIST_FOREACH(child, &bs->children, next) {
4472 QDict *new_child_options = NULL;
4473 bool child_keep_old = keep_old_opts;
4475 /* reopen can only change the options of block devices that were
4476 * implicitly created and inherited options. For other (referenced)
4477 * block devices, a syntax like "backing.foo" results in an error. */
4478 if (child->bs->inherits_from != bs) {
4479 continue;
4482 /* Check if the options contain a child reference */
4483 if (qdict_haskey(options, child->name)) {
4484 const char *childref = qdict_get_try_str(options, child->name);
4486 * The current child must not be reopened if the child
4487 * reference is null or points to a different node.
4489 if (g_strcmp0(childref, child->bs->node_name)) {
4490 continue;
4493 * If the child reference points to the current child then
4494 * reopen it with its existing set of options (note that
4495 * it can still inherit new options from the parent).
4497 child_keep_old = true;
4498 } else {
4499 /* Extract child options ("child-name.*") */
4500 char *child_key_dot = g_strdup_printf("%s.", child->name);
4501 qdict_extract_subqdict(explicit_options, NULL, child_key_dot);
4502 qdict_extract_subqdict(options, &new_child_options, child_key_dot);
4503 g_free(child_key_dot);
4506 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
4507 child->klass, child->role, bs->drv->is_format,
4508 options, flags, child_keep_old);
4511 return bs_queue;
4514 /* To be called with bs->aio_context locked */
4515 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
4516 BlockDriverState *bs,
4517 QDict *options, bool keep_old_opts)
4519 GLOBAL_STATE_CODE();
4521 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false,
4522 NULL, 0, keep_old_opts);
4525 void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue)
4527 GLOBAL_STATE_CODE();
4528 if (bs_queue) {
4529 BlockReopenQueueEntry *bs_entry, *next;
4530 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
4531 AioContext *ctx = bdrv_get_aio_context(bs_entry->state.bs);
4533 aio_context_acquire(ctx);
4534 bdrv_drained_end(bs_entry->state.bs);
4535 aio_context_release(ctx);
4537 qobject_unref(bs_entry->state.explicit_options);
4538 qobject_unref(bs_entry->state.options);
4539 g_free(bs_entry);
4541 g_free(bs_queue);
4546 * Reopen multiple BlockDriverStates atomically & transactionally.
4548 * The queue passed in (bs_queue) must have been built up previous
4549 * via bdrv_reopen_queue().
4551 * Reopens all BDS specified in the queue, with the appropriate
4552 * flags. All devices are prepared for reopen, and failure of any
4553 * device will cause all device changes to be abandoned, and intermediate
4554 * data cleaned up.
4556 * If all devices prepare successfully, then the changes are committed
4557 * to all devices.
4559 * All affected nodes must be drained between bdrv_reopen_queue() and
4560 * bdrv_reopen_multiple().
4562 * To be called from the main thread, with all other AioContexts unlocked.
4564 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
4566 int ret = -1;
4567 BlockReopenQueueEntry *bs_entry, *next;
4568 AioContext *ctx;
4569 Transaction *tran = tran_new();
4570 g_autoptr(GSList) refresh_list = NULL;
4572 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
4573 assert(bs_queue != NULL);
4574 GLOBAL_STATE_CODE();
4576 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4577 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4578 aio_context_acquire(ctx);
4579 ret = bdrv_flush(bs_entry->state.bs);
4580 aio_context_release(ctx);
4581 if (ret < 0) {
4582 error_setg_errno(errp, -ret, "Error flushing drive");
4583 goto abort;
4587 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4588 assert(bs_entry->state.bs->quiesce_counter > 0);
4589 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4590 aio_context_acquire(ctx);
4591 ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp);
4592 aio_context_release(ctx);
4593 if (ret < 0) {
4594 goto abort;
4596 bs_entry->prepared = true;
4599 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4600 BDRVReopenState *state = &bs_entry->state;
4602 refresh_list = g_slist_prepend(refresh_list, state->bs);
4603 if (state->old_backing_bs) {
4604 refresh_list = g_slist_prepend(refresh_list, state->old_backing_bs);
4606 if (state->old_file_bs) {
4607 refresh_list = g_slist_prepend(refresh_list, state->old_file_bs);
4612 * Note that file-posix driver rely on permission update done during reopen
4613 * (even if no permission changed), because it wants "new" permissions for
4614 * reconfiguring the fd and that's why it does it in raw_check_perm(), not
4615 * in raw_reopen_prepare() which is called with "old" permissions.
4617 bdrv_graph_rdlock_main_loop();
4618 ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp);
4619 bdrv_graph_rdunlock_main_loop();
4621 if (ret < 0) {
4622 goto abort;
4626 * If we reach this point, we have success and just need to apply the
4627 * changes.
4629 * Reverse order is used to comfort qcow2 driver: on commit it need to write
4630 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But
4631 * children are usually goes after parents in reopen-queue, so go from last
4632 * to first element.
4634 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
4635 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4636 aio_context_acquire(ctx);
4637 bdrv_reopen_commit(&bs_entry->state);
4638 aio_context_release(ctx);
4641 bdrv_graph_wrlock(NULL);
4642 tran_commit(tran);
4643 bdrv_graph_wrunlock();
4645 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
4646 BlockDriverState *bs = bs_entry->state.bs;
4648 if (bs->drv->bdrv_reopen_commit_post) {
4649 ctx = bdrv_get_aio_context(bs);
4650 aio_context_acquire(ctx);
4651 bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
4652 aio_context_release(ctx);
4656 ret = 0;
4657 goto cleanup;
4659 abort:
4660 bdrv_graph_wrlock(NULL);
4661 tran_abort(tran);
4662 bdrv_graph_wrunlock();
4664 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
4665 if (bs_entry->prepared) {
4666 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4667 aio_context_acquire(ctx);
4668 bdrv_reopen_abort(&bs_entry->state);
4669 aio_context_release(ctx);
4673 cleanup:
4674 bdrv_reopen_queue_free(bs_queue);
4676 return ret;
4679 int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
4680 Error **errp)
4682 AioContext *ctx = bdrv_get_aio_context(bs);
4683 BlockReopenQueue *queue;
4684 int ret;
4686 GLOBAL_STATE_CODE();
4688 queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
4690 if (ctx != qemu_get_aio_context()) {
4691 aio_context_release(ctx);
4693 ret = bdrv_reopen_multiple(queue, errp);
4695 if (ctx != qemu_get_aio_context()) {
4696 aio_context_acquire(ctx);
4699 return ret;
4702 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
4703 Error **errp)
4705 QDict *opts = qdict_new();
4707 GLOBAL_STATE_CODE();
4709 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
4711 return bdrv_reopen(bs, opts, true, errp);
4715 * Take a BDRVReopenState and check if the value of 'backing' in the
4716 * reopen_state->options QDict is valid or not.
4718 * If 'backing' is missing from the QDict then return 0.
4720 * If 'backing' contains the node name of the backing file of
4721 * reopen_state->bs then return 0.
4723 * If 'backing' contains a different node name (or is null) then check
4724 * whether the current backing file can be replaced with the new one.
4725 * If that's the case then reopen_state->replace_backing_bs is set to
4726 * true and reopen_state->new_backing_bs contains a pointer to the new
4727 * backing BlockDriverState (or NULL).
4729 * After calling this function, the transaction @tran may only be completed
4730 * while holding a writer lock for the graph.
4732 * Return 0 on success, otherwise return < 0 and set @errp.
4734 * The caller must hold the AioContext lock of @reopen_state->bs.
4735 * @reopen_state->bs can move to a different AioContext in this function.
4736 * Callers must make sure that their AioContext locking is still correct after
4737 * this.
4739 static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
4740 bool is_backing, Transaction *tran,
4741 Error **errp)
4743 BlockDriverState *bs = reopen_state->bs;
4744 BlockDriverState *new_child_bs;
4745 BlockDriverState *old_child_bs = is_backing ? child_bs(bs->backing) :
4746 child_bs(bs->file);
4747 const char *child_name = is_backing ? "backing" : "file";
4748 QObject *value;
4749 const char *str;
4750 AioContext *ctx, *old_ctx;
4751 int ret;
4753 GLOBAL_STATE_CODE();
4755 value = qdict_get(reopen_state->options, child_name);
4756 if (value == NULL) {
4757 return 0;
4760 switch (qobject_type(value)) {
4761 case QTYPE_QNULL:
4762 assert(is_backing); /* The 'file' option does not allow a null value */
4763 new_child_bs = NULL;
4764 break;
4765 case QTYPE_QSTRING:
4766 str = qstring_get_str(qobject_to(QString, value));
4767 new_child_bs = bdrv_lookup_bs(NULL, str, errp);
4768 if (new_child_bs == NULL) {
4769 return -EINVAL;
4770 } else if (bdrv_recurse_has_child(new_child_bs, bs)) {
4771 error_setg(errp, "Making '%s' a %s child of '%s' would create a "
4772 "cycle", str, child_name, bs->node_name);
4773 return -EINVAL;
4775 break;
4776 default:
4778 * The options QDict has been flattened, so 'backing' and 'file'
4779 * do not allow any other data type here.
4781 g_assert_not_reached();
4784 if (old_child_bs == new_child_bs) {
4785 return 0;
4788 if (old_child_bs) {
4789 if (bdrv_skip_implicit_filters(old_child_bs) == new_child_bs) {
4790 return 0;
4793 if (old_child_bs->implicit) {
4794 error_setg(errp, "Cannot replace implicit %s child of %s",
4795 child_name, bs->node_name);
4796 return -EPERM;
4800 if (bs->drv->is_filter && !old_child_bs) {
4802 * Filters always have a file or a backing child, so we are trying to
4803 * change wrong child
4805 error_setg(errp, "'%s' is a %s filter node that does not support a "
4806 "%s child", bs->node_name, bs->drv->format_name, child_name);
4807 return -EINVAL;
4810 if (is_backing) {
4811 reopen_state->old_backing_bs = old_child_bs;
4812 } else {
4813 reopen_state->old_file_bs = old_child_bs;
4816 if (old_child_bs) {
4817 bdrv_ref(old_child_bs);
4818 bdrv_drained_begin(old_child_bs);
4821 old_ctx = bdrv_get_aio_context(bs);
4822 ctx = bdrv_get_aio_context(new_child_bs);
4823 if (old_ctx != ctx) {
4824 aio_context_release(old_ctx);
4825 aio_context_acquire(ctx);
4828 bdrv_graph_wrlock(new_child_bs);
4830 ret = bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing,
4831 tran, errp);
4833 bdrv_graph_wrunlock();
4835 if (old_ctx != ctx) {
4836 aio_context_release(ctx);
4837 aio_context_acquire(old_ctx);
4840 if (old_child_bs) {
4841 bdrv_drained_end(old_child_bs);
4842 bdrv_unref(old_child_bs);
4845 return ret;
4849 * Prepares a BlockDriverState for reopen. All changes are staged in the
4850 * 'opaque' field of the BDRVReopenState, which is used and allocated by
4851 * the block driver layer .bdrv_reopen_prepare()
4853 * bs is the BlockDriverState to reopen
4854 * flags are the new open flags
4855 * queue is the reopen queue
4857 * Returns 0 on success, non-zero on error. On error errp will be set
4858 * as well.
4860 * On failure, bdrv_reopen_abort() will be called to clean up any data.
4861 * It is the responsibility of the caller to then call the abort() or
4862 * commit() for any other BDS that have been left in a prepare() state
4864 * The caller must hold the AioContext lock of @reopen_state->bs.
4866 * After calling this function, the transaction @change_child_tran may only be
4867 * completed while holding a writer lock for the graph.
4869 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
4870 BlockReopenQueue *queue,
4871 Transaction *change_child_tran, Error **errp)
4873 int ret = -1;
4874 int old_flags;
4875 Error *local_err = NULL;
4876 BlockDriver *drv;
4877 QemuOpts *opts;
4878 QDict *orig_reopen_opts;
4879 char *discard = NULL;
4880 bool read_only;
4881 bool drv_prepared = false;
4883 assert(reopen_state != NULL);
4884 assert(reopen_state->bs->drv != NULL);
4885 GLOBAL_STATE_CODE();
4886 drv = reopen_state->bs->drv;
4888 /* This function and each driver's bdrv_reopen_prepare() remove
4889 * entries from reopen_state->options as they are processed, so
4890 * we need to make a copy of the original QDict. */
4891 orig_reopen_opts = qdict_clone_shallow(reopen_state->options);
4893 /* Process generic block layer options */
4894 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4895 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) {
4896 ret = -EINVAL;
4897 goto error;
4900 /* This was already called in bdrv_reopen_queue_child() so the flags
4901 * are up-to-date. This time we simply want to remove the options from
4902 * QemuOpts in order to indicate that they have been processed. */
4903 old_flags = reopen_state->flags;
4904 update_flags_from_options(&reopen_state->flags, opts);
4905 assert(old_flags == reopen_state->flags);
4907 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD);
4908 if (discard != NULL) {
4909 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) {
4910 error_setg(errp, "Invalid discard option");
4911 ret = -EINVAL;
4912 goto error;
4916 reopen_state->detect_zeroes =
4917 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err);
4918 if (local_err) {
4919 error_propagate(errp, local_err);
4920 ret = -EINVAL;
4921 goto error;
4924 /* All other options (including node-name and driver) must be unchanged.
4925 * Put them back into the QDict, so that they are checked at the end
4926 * of this function. */
4927 qemu_opts_to_qdict(opts, reopen_state->options);
4929 /* If we are to stay read-only, do not allow permission change
4930 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
4931 * not set, or if the BDS still has copy_on_read enabled */
4932 read_only = !(reopen_state->flags & BDRV_O_RDWR);
4933 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
4934 if (local_err) {
4935 error_propagate(errp, local_err);
4936 goto error;
4939 if (drv->bdrv_reopen_prepare) {
4941 * If a driver-specific option is missing, it means that we
4942 * should reset it to its default value.
4943 * But not all options allow that, so we need to check it first.
4945 ret = bdrv_reset_options_allowed(reopen_state->bs,
4946 reopen_state->options, errp);
4947 if (ret) {
4948 goto error;
4951 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
4952 if (ret) {
4953 if (local_err != NULL) {
4954 error_propagate(errp, local_err);
4955 } else {
4956 bdrv_refresh_filename(reopen_state->bs);
4957 error_setg(errp, "failed while preparing to reopen image '%s'",
4958 reopen_state->bs->filename);
4960 goto error;
4962 } else {
4963 /* It is currently mandatory to have a bdrv_reopen_prepare()
4964 * handler for each supported drv. */
4965 error_setg(errp, "Block format '%s' used by node '%s' "
4966 "does not support reopening files", drv->format_name,
4967 bdrv_get_device_or_node_name(reopen_state->bs));
4968 ret = -1;
4969 goto error;
4972 drv_prepared = true;
4975 * We must provide the 'backing' option if the BDS has a backing
4976 * file or if the image file has a backing file name as part of
4977 * its metadata. Otherwise the 'backing' option can be omitted.
4979 if (drv->supports_backing && reopen_state->backing_missing &&
4980 (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) {
4981 error_setg(errp, "backing is missing for '%s'",
4982 reopen_state->bs->node_name);
4983 ret = -EINVAL;
4984 goto error;
4988 * Allow changing the 'backing' option. The new value can be
4989 * either a reference to an existing node (using its node name)
4990 * or NULL to simply detach the current backing file.
4992 ret = bdrv_reopen_parse_file_or_backing(reopen_state, true,
4993 change_child_tran, errp);
4994 if (ret < 0) {
4995 goto error;
4997 qdict_del(reopen_state->options, "backing");
4999 /* Allow changing the 'file' option. In this case NULL is not allowed */
5000 ret = bdrv_reopen_parse_file_or_backing(reopen_state, false,
5001 change_child_tran, errp);
5002 if (ret < 0) {
5003 goto error;
5005 qdict_del(reopen_state->options, "file");
5007 /* Options that are not handled are only okay if they are unchanged
5008 * compared to the old state. It is expected that some options are only
5009 * used for the initial open, but not reopen (e.g. filename) */
5010 if (qdict_size(reopen_state->options)) {
5011 const QDictEntry *entry = qdict_first(reopen_state->options);
5013 do {
5014 QObject *new = entry->value;
5015 QObject *old = qdict_get(reopen_state->bs->options, entry->key);
5017 /* Allow child references (child_name=node_name) as long as they
5018 * point to the current child (i.e. everything stays the same). */
5019 if (qobject_type(new) == QTYPE_QSTRING) {
5020 BdrvChild *child;
5021 QLIST_FOREACH(child, &reopen_state->bs->children, next) {
5022 if (!strcmp(child->name, entry->key)) {
5023 break;
5027 if (child) {
5028 if (!strcmp(child->bs->node_name,
5029 qstring_get_str(qobject_to(QString, new)))) {
5030 continue; /* Found child with this name, skip option */
5036 * TODO: When using -drive to specify blockdev options, all values
5037 * will be strings; however, when using -blockdev, blockdev-add or
5038 * filenames using the json:{} pseudo-protocol, they will be
5039 * correctly typed.
5040 * In contrast, reopening options are (currently) always strings
5041 * (because you can only specify them through qemu-io; all other
5042 * callers do not specify any options).
5043 * Therefore, when using anything other than -drive to create a BDS,
5044 * this cannot detect non-string options as unchanged, because
5045 * qobject_is_equal() always returns false for objects of different
5046 * type. In the future, this should be remedied by correctly typing
5047 * all options. For now, this is not too big of an issue because
5048 * the user can simply omit options which cannot be changed anyway,
5049 * so they will stay unchanged.
5051 if (!qobject_is_equal(new, old)) {
5052 error_setg(errp, "Cannot change the option '%s'", entry->key);
5053 ret = -EINVAL;
5054 goto error;
5056 } while ((entry = qdict_next(reopen_state->options, entry)));
5059 ret = 0;
5061 /* Restore the original reopen_state->options QDict */
5062 qobject_unref(reopen_state->options);
5063 reopen_state->options = qobject_ref(orig_reopen_opts);
5065 error:
5066 if (ret < 0 && drv_prepared) {
5067 /* drv->bdrv_reopen_prepare() has succeeded, so we need to
5068 * call drv->bdrv_reopen_abort() before signaling an error
5069 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort()
5070 * when the respective bdrv_reopen_prepare() has failed) */
5071 if (drv->bdrv_reopen_abort) {
5072 drv->bdrv_reopen_abort(reopen_state);
5075 qemu_opts_del(opts);
5076 qobject_unref(orig_reopen_opts);
5077 g_free(discard);
5078 return ret;
5082 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and
5083 * makes them final by swapping the staging BlockDriverState contents into
5084 * the active BlockDriverState contents.
5086 static void bdrv_reopen_commit(BDRVReopenState *reopen_state)
5088 BlockDriver *drv;
5089 BlockDriverState *bs;
5090 BdrvChild *child;
5092 assert(reopen_state != NULL);
5093 bs = reopen_state->bs;
5094 drv = bs->drv;
5095 assert(drv != NULL);
5096 GLOBAL_STATE_CODE();
5098 /* If there are any driver level actions to take */
5099 if (drv->bdrv_reopen_commit) {
5100 drv->bdrv_reopen_commit(reopen_state);
5103 /* set BDS specific flags now */
5104 qobject_unref(bs->explicit_options);
5105 qobject_unref(bs->options);
5106 qobject_ref(reopen_state->explicit_options);
5107 qobject_ref(reopen_state->options);
5109 bs->explicit_options = reopen_state->explicit_options;
5110 bs->options = reopen_state->options;
5111 bs->open_flags = reopen_state->flags;
5112 bs->detect_zeroes = reopen_state->detect_zeroes;
5114 /* Remove child references from bs->options and bs->explicit_options.
5115 * Child options were already removed in bdrv_reopen_queue_child() */
5116 QLIST_FOREACH(child, &bs->children, next) {
5117 qdict_del(bs->explicit_options, child->name);
5118 qdict_del(bs->options, child->name);
5120 /* backing is probably removed, so it's not handled by previous loop */
5121 qdict_del(bs->explicit_options, "backing");
5122 qdict_del(bs->options, "backing");
5124 bdrv_graph_rdlock_main_loop();
5125 bdrv_refresh_limits(bs, NULL, NULL);
5126 bdrv_graph_rdunlock_main_loop();
5127 bdrv_refresh_total_sectors(bs, bs->total_sectors);
5131 * Abort the reopen, and delete and free the staged changes in
5132 * reopen_state
5134 static void bdrv_reopen_abort(BDRVReopenState *reopen_state)
5136 BlockDriver *drv;
5138 assert(reopen_state != NULL);
5139 drv = reopen_state->bs->drv;
5140 assert(drv != NULL);
5141 GLOBAL_STATE_CODE();
5143 if (drv->bdrv_reopen_abort) {
5144 drv->bdrv_reopen_abort(reopen_state);
5149 static void bdrv_close(BlockDriverState *bs)
5151 BdrvAioNotifier *ban, *ban_next;
5152 BdrvChild *child, *next;
5154 GLOBAL_STATE_CODE();
5155 assert(!bs->refcnt);
5157 bdrv_drained_begin(bs); /* complete I/O */
5158 bdrv_flush(bs);
5159 bdrv_drain(bs); /* in case flush left pending I/O */
5161 if (bs->drv) {
5162 if (bs->drv->bdrv_close) {
5163 /* Must unfreeze all children, so bdrv_unref_child() works */
5164 bs->drv->bdrv_close(bs);
5166 bs->drv = NULL;
5169 bdrv_graph_wrlock(NULL);
5170 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
5171 bdrv_unref_child(bs, child);
5173 bdrv_graph_wrunlock();
5175 assert(!bs->backing);
5176 assert(!bs->file);
5177 g_free(bs->opaque);
5178 bs->opaque = NULL;
5179 qatomic_set(&bs->copy_on_read, 0);
5180 bs->backing_file[0] = '\0';
5181 bs->backing_format[0] = '\0';
5182 bs->total_sectors = 0;
5183 bs->encrypted = false;
5184 bs->sg = false;
5185 qobject_unref(bs->options);
5186 qobject_unref(bs->explicit_options);
5187 bs->options = NULL;
5188 bs->explicit_options = NULL;
5189 qobject_unref(bs->full_open_options);
5190 bs->full_open_options = NULL;
5191 g_free(bs->block_status_cache);
5192 bs->block_status_cache = NULL;
5194 bdrv_release_named_dirty_bitmaps(bs);
5195 assert(QLIST_EMPTY(&bs->dirty_bitmaps));
5197 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
5198 g_free(ban);
5200 QLIST_INIT(&bs->aio_notifiers);
5201 bdrv_drained_end(bs);
5204 * If we're still inside some bdrv_drain_all_begin()/end() sections, end
5205 * them now since this BDS won't exist anymore when bdrv_drain_all_end()
5206 * gets called.
5208 if (bs->quiesce_counter) {
5209 bdrv_drain_all_end_quiesce(bs);
5213 void bdrv_close_all(void)
5215 GLOBAL_STATE_CODE();
5216 assert(job_next(NULL) == NULL);
5218 /* Drop references from requests still in flight, such as canceled block
5219 * jobs whose AIO context has not been polled yet */
5220 bdrv_drain_all();
5222 blk_remove_all_bs();
5223 blockdev_close_all_bdrv_states();
5225 assert(QTAILQ_EMPTY(&all_bdrv_states));
5228 static bool GRAPH_RDLOCK should_update_child(BdrvChild *c, BlockDriverState *to)
5230 GQueue *queue;
5231 GHashTable *found;
5232 bool ret;
5234 if (c->klass->stay_at_node) {
5235 return false;
5238 /* If the child @c belongs to the BDS @to, replacing the current
5239 * c->bs by @to would mean to create a loop.
5241 * Such a case occurs when appending a BDS to a backing chain.
5242 * For instance, imagine the following chain:
5244 * guest device -> node A -> further backing chain...
5246 * Now we create a new BDS B which we want to put on top of this
5247 * chain, so we first attach A as its backing node:
5249 * node B
5252 * guest device -> node A -> further backing chain...
5254 * Finally we want to replace A by B. When doing that, we want to
5255 * replace all pointers to A by pointers to B -- except for the
5256 * pointer from B because (1) that would create a loop, and (2)
5257 * that pointer should simply stay intact:
5259 * guest device -> node B
5262 * node A -> further backing chain...
5264 * In general, when replacing a node A (c->bs) by a node B (@to),
5265 * if A is a child of B, that means we cannot replace A by B there
5266 * because that would create a loop. Silently detaching A from B
5267 * is also not really an option. So overall just leaving A in
5268 * place there is the most sensible choice.
5270 * We would also create a loop in any cases where @c is only
5271 * indirectly referenced by @to. Prevent this by returning false
5272 * if @c is found (by breadth-first search) anywhere in the whole
5273 * subtree of @to.
5276 ret = true;
5277 found = g_hash_table_new(NULL, NULL);
5278 g_hash_table_add(found, to);
5279 queue = g_queue_new();
5280 g_queue_push_tail(queue, to);
5282 while (!g_queue_is_empty(queue)) {
5283 BlockDriverState *v = g_queue_pop_head(queue);
5284 BdrvChild *c2;
5286 QLIST_FOREACH(c2, &v->children, next) {
5287 if (c2 == c) {
5288 ret = false;
5289 break;
5292 if (g_hash_table_contains(found, c2->bs)) {
5293 continue;
5296 g_queue_push_tail(queue, c2->bs);
5297 g_hash_table_add(found, c2->bs);
5301 g_queue_free(queue);
5302 g_hash_table_destroy(found);
5304 return ret;
5307 static void bdrv_remove_child_commit(void *opaque)
5309 GLOBAL_STATE_CODE();
5310 bdrv_child_free(opaque);
5313 static TransactionActionDrv bdrv_remove_child_drv = {
5314 .commit = bdrv_remove_child_commit,
5318 * Function doesn't update permissions, caller is responsible for this.
5320 * @child->bs (if non-NULL) must be drained.
5322 * After calling this function, the transaction @tran may only be completed
5323 * while holding a writer lock for the graph.
5325 static void GRAPH_WRLOCK bdrv_remove_child(BdrvChild *child, Transaction *tran)
5327 if (!child) {
5328 return;
5331 if (child->bs) {
5332 assert(child->quiesced_parent);
5333 bdrv_replace_child_tran(child, NULL, tran);
5336 tran_add(tran, &bdrv_remove_child_drv, child);
5340 * Both @from and @to (if non-NULL) must be drained. @to must be kept drained
5341 * until the transaction is completed.
5343 * After calling this function, the transaction @tran may only be completed
5344 * while holding a writer lock for the graph.
5346 static int GRAPH_WRLOCK
5347 bdrv_replace_node_noperm(BlockDriverState *from,
5348 BlockDriverState *to,
5349 bool auto_skip, Transaction *tran,
5350 Error **errp)
5352 BdrvChild *c, *next;
5354 GLOBAL_STATE_CODE();
5356 assert(from->quiesce_counter);
5357 assert(to->quiesce_counter);
5359 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
5360 assert(c->bs == from);
5361 if (!should_update_child(c, to)) {
5362 if (auto_skip) {
5363 continue;
5365 error_setg(errp, "Should not change '%s' link to '%s'",
5366 c->name, from->node_name);
5367 return -EINVAL;
5369 if (c->frozen) {
5370 error_setg(errp, "Cannot change '%s' link to '%s'",
5371 c->name, from->node_name);
5372 return -EPERM;
5374 bdrv_replace_child_tran(c, to, tran);
5377 return 0;
5381 * With auto_skip=true bdrv_replace_node_common skips updating from parents
5382 * if it creates a parent-child relation loop or if parent is block-job.
5384 * With auto_skip=false the error is returned if from has a parent which should
5385 * not be updated.
5387 * With @detach_subchain=true @to must be in a backing chain of @from. In this
5388 * case backing link of the cow-parent of @to is removed.
5390 static int bdrv_replace_node_common(BlockDriverState *from,
5391 BlockDriverState *to,
5392 bool auto_skip, bool detach_subchain,
5393 Error **errp)
5395 Transaction *tran = tran_new();
5396 g_autoptr(GSList) refresh_list = NULL;
5397 BlockDriverState *to_cow_parent = NULL;
5398 int ret;
5400 GLOBAL_STATE_CODE();
5402 if (detach_subchain) {
5403 assert(bdrv_chain_contains(from, to));
5404 assert(from != to);
5405 for (to_cow_parent = from;
5406 bdrv_filter_or_cow_bs(to_cow_parent) != to;
5407 to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent))
5413 /* Make sure that @from doesn't go away until we have successfully attached
5414 * all of its parents to @to. */
5415 bdrv_ref(from);
5417 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
5418 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to));
5419 bdrv_drained_begin(from);
5420 bdrv_drained_begin(to);
5422 bdrv_graph_wrlock(to);
5425 * Do the replacement without permission update.
5426 * Replacement may influence the permissions, we should calculate new
5427 * permissions based on new graph. If we fail, we'll roll-back the
5428 * replacement.
5430 ret = bdrv_replace_node_noperm(from, to, auto_skip, tran, errp);
5431 if (ret < 0) {
5432 goto out;
5435 if (detach_subchain) {
5436 /* to_cow_parent is already drained because from is drained */
5437 bdrv_remove_child(bdrv_filter_or_cow_child(to_cow_parent), tran);
5440 refresh_list = g_slist_prepend(refresh_list, to);
5441 refresh_list = g_slist_prepend(refresh_list, from);
5443 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
5444 if (ret < 0) {
5445 goto out;
5448 ret = 0;
5450 out:
5451 tran_finalize(tran, ret);
5452 bdrv_graph_wrunlock();
5454 bdrv_drained_end(to);
5455 bdrv_drained_end(from);
5456 bdrv_unref(from);
5458 return ret;
5461 int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
5462 Error **errp)
5464 GLOBAL_STATE_CODE();
5466 return bdrv_replace_node_common(from, to, true, false, errp);
5469 int bdrv_drop_filter(BlockDriverState *bs, Error **errp)
5471 GLOBAL_STATE_CODE();
5473 return bdrv_replace_node_common(bs, bdrv_filter_or_cow_bs(bs), true, true,
5474 errp);
5478 * Add new bs contents at the top of an image chain while the chain is
5479 * live, while keeping required fields on the top layer.
5481 * This will modify the BlockDriverState fields, and swap contents
5482 * between bs_new and bs_top. Both bs_new and bs_top are modified.
5484 * bs_new must not be attached to a BlockBackend and must not have backing
5485 * child.
5487 * This function does not create any image files.
5489 * The caller must hold the AioContext lock for @bs_top.
5491 int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
5492 Error **errp)
5494 int ret;
5495 BdrvChild *child;
5496 Transaction *tran = tran_new();
5497 AioContext *old_context, *new_context = NULL;
5499 GLOBAL_STATE_CODE();
5501 assert(!bs_new->backing);
5503 old_context = bdrv_get_aio_context(bs_top);
5504 bdrv_drained_begin(bs_top);
5507 * bdrv_drained_begin() requires that only the AioContext of the drained
5508 * node is locked, and at this point it can still differ from the AioContext
5509 * of bs_top.
5511 new_context = bdrv_get_aio_context(bs_new);
5512 aio_context_release(old_context);
5513 aio_context_acquire(new_context);
5514 bdrv_drained_begin(bs_new);
5515 aio_context_release(new_context);
5516 aio_context_acquire(old_context);
5517 new_context = NULL;
5519 bdrv_graph_wrlock(bs_top);
5521 child = bdrv_attach_child_noperm(bs_new, bs_top, "backing",
5522 &child_of_bds, bdrv_backing_role(bs_new),
5523 tran, errp);
5524 if (!child) {
5525 ret = -EINVAL;
5526 goto out;
5530 * bdrv_attach_child_noperm could change the AioContext of bs_top and
5531 * bs_new, but at least they are in the same AioContext now. This is the
5532 * AioContext that we need to lock for the rest of the function.
5534 new_context = bdrv_get_aio_context(bs_top);
5536 if (old_context != new_context) {
5537 aio_context_release(old_context);
5538 aio_context_acquire(new_context);
5541 ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp);
5542 if (ret < 0) {
5543 goto out;
5546 ret = bdrv_refresh_perms(bs_new, tran, errp);
5547 out:
5548 tran_finalize(tran, ret);
5550 bdrv_refresh_limits(bs_top, NULL, NULL);
5551 bdrv_graph_wrunlock();
5553 bdrv_drained_end(bs_top);
5554 bdrv_drained_end(bs_new);
5556 if (new_context && old_context != new_context) {
5557 aio_context_release(new_context);
5558 aio_context_acquire(old_context);
5561 return ret;
5564 /* Not for empty child */
5565 int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
5566 Error **errp)
5568 int ret;
5569 Transaction *tran = tran_new();
5570 g_autoptr(GSList) refresh_list = NULL;
5571 BlockDriverState *old_bs = child->bs;
5573 GLOBAL_STATE_CODE();
5575 bdrv_ref(old_bs);
5576 bdrv_drained_begin(old_bs);
5577 bdrv_drained_begin(new_bs);
5578 bdrv_graph_wrlock(new_bs);
5580 bdrv_replace_child_tran(child, new_bs, tran);
5582 refresh_list = g_slist_prepend(refresh_list, old_bs);
5583 refresh_list = g_slist_prepend(refresh_list, new_bs);
5585 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
5587 tran_finalize(tran, ret);
5589 bdrv_graph_wrunlock();
5590 bdrv_drained_end(old_bs);
5591 bdrv_drained_end(new_bs);
5592 bdrv_unref(old_bs);
5594 return ret;
5597 static void bdrv_delete(BlockDriverState *bs)
5599 assert(bdrv_op_blocker_is_empty(bs));
5600 assert(!bs->refcnt);
5601 GLOBAL_STATE_CODE();
5603 /* remove from list, if necessary */
5604 if (bs->node_name[0] != '\0') {
5605 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
5607 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
5609 bdrv_close(bs);
5611 qemu_mutex_destroy(&bs->reqs_lock);
5613 g_free(bs);
5618 * Replace @bs by newly created block node.
5620 * @options is a QDict of options to pass to the block drivers, or NULL for an
5621 * empty set of options. The reference to the QDict belongs to the block layer
5622 * after the call (even on failure), so if the caller intends to reuse the
5623 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
5625 * The caller holds the AioContext lock for @bs. It must make sure that @bs
5626 * stays in the same AioContext, i.e. @options must not refer to nodes in a
5627 * different AioContext.
5629 BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options,
5630 int flags, Error **errp)
5632 ERRP_GUARD();
5633 int ret;
5634 AioContext *ctx = bdrv_get_aio_context(bs);
5635 BlockDriverState *new_node_bs = NULL;
5636 const char *drvname, *node_name;
5637 BlockDriver *drv;
5639 drvname = qdict_get_try_str(options, "driver");
5640 if (!drvname) {
5641 error_setg(errp, "driver is not specified");
5642 goto fail;
5645 drv = bdrv_find_format(drvname);
5646 if (!drv) {
5647 error_setg(errp, "Unknown driver: '%s'", drvname);
5648 goto fail;
5651 node_name = qdict_get_try_str(options, "node-name");
5653 GLOBAL_STATE_CODE();
5655 aio_context_release(ctx);
5656 aio_context_acquire(qemu_get_aio_context());
5657 new_node_bs = bdrv_new_open_driver_opts(drv, node_name, options, flags,
5658 errp);
5659 aio_context_release(qemu_get_aio_context());
5660 aio_context_acquire(ctx);
5661 assert(bdrv_get_aio_context(bs) == ctx);
5663 options = NULL; /* bdrv_new_open_driver() eats options */
5664 if (!new_node_bs) {
5665 error_prepend(errp, "Could not create node: ");
5666 goto fail;
5669 bdrv_drained_begin(bs);
5670 ret = bdrv_replace_node(bs, new_node_bs, errp);
5671 bdrv_drained_end(bs);
5673 if (ret < 0) {
5674 error_prepend(errp, "Could not replace node: ");
5675 goto fail;
5678 return new_node_bs;
5680 fail:
5681 qobject_unref(options);
5682 bdrv_unref(new_node_bs);
5683 return NULL;
5687 * Run consistency checks on an image
5689 * Returns 0 if the check could be completed (it doesn't mean that the image is
5690 * free of errors) or -errno when an internal error occurred. The results of the
5691 * check are stored in res.
5693 int coroutine_fn bdrv_co_check(BlockDriverState *bs,
5694 BdrvCheckResult *res, BdrvCheckMode fix)
5696 IO_CODE();
5697 assert_bdrv_graph_readable();
5698 if (bs->drv == NULL) {
5699 return -ENOMEDIUM;
5701 if (bs->drv->bdrv_co_check == NULL) {
5702 return -ENOTSUP;
5705 memset(res, 0, sizeof(*res));
5706 return bs->drv->bdrv_co_check(bs, res, fix);
5710 * Return values:
5711 * 0 - success
5712 * -EINVAL - backing format specified, but no file
5713 * -ENOSPC - can't update the backing file because no space is left in the
5714 * image file header
5715 * -ENOTSUP - format driver doesn't support changing the backing file
5717 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
5718 const char *backing_fmt, bool require)
5720 BlockDriver *drv = bs->drv;
5721 int ret;
5723 GLOBAL_STATE_CODE();
5725 if (!drv) {
5726 return -ENOMEDIUM;
5729 /* Backing file format doesn't make sense without a backing file */
5730 if (backing_fmt && !backing_file) {
5731 return -EINVAL;
5734 if (require && backing_file && !backing_fmt) {
5735 return -EINVAL;
5738 if (drv->bdrv_change_backing_file != NULL) {
5739 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
5740 } else {
5741 ret = -ENOTSUP;
5744 if (ret == 0) {
5745 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
5746 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
5747 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
5748 backing_file ?: "");
5750 return ret;
5754 * Finds the first non-filter node above bs in the chain between
5755 * active and bs. The returned node is either an immediate parent of
5756 * bs, or there are only filter nodes between the two.
5758 * Returns NULL if bs is not found in active's image chain,
5759 * or if active == bs.
5761 * Returns the bottommost base image if bs == NULL.
5763 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
5764 BlockDriverState *bs)
5767 GLOBAL_STATE_CODE();
5769 bs = bdrv_skip_filters(bs);
5770 active = bdrv_skip_filters(active);
5772 while (active) {
5773 BlockDriverState *next = bdrv_backing_chain_next(active);
5774 if (bs == next) {
5775 return active;
5777 active = next;
5780 return NULL;
5783 /* Given a BDS, searches for the base layer. */
5784 BlockDriverState *bdrv_find_base(BlockDriverState *bs)
5786 GLOBAL_STATE_CODE();
5788 return bdrv_find_overlay(bs, NULL);
5792 * Return true if at least one of the COW (backing) and filter links
5793 * between @bs and @base is frozen. @errp is set if that's the case.
5794 * @base must be reachable from @bs, or NULL.
5796 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
5797 Error **errp)
5799 BlockDriverState *i;
5800 BdrvChild *child;
5802 GLOBAL_STATE_CODE();
5804 for (i = bs; i != base; i = child_bs(child)) {
5805 child = bdrv_filter_or_cow_child(i);
5807 if (child && child->frozen) {
5808 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
5809 child->name, i->node_name, child->bs->node_name);
5810 return true;
5814 return false;
5818 * Freeze all COW (backing) and filter links between @bs and @base.
5819 * If any of the links is already frozen the operation is aborted and
5820 * none of the links are modified.
5821 * @base must be reachable from @bs, or NULL.
5822 * Returns 0 on success. On failure returns < 0 and sets @errp.
5824 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
5825 Error **errp)
5827 BlockDriverState *i;
5828 BdrvChild *child;
5830 GLOBAL_STATE_CODE();
5832 if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
5833 return -EPERM;
5836 for (i = bs; i != base; i = child_bs(child)) {
5837 child = bdrv_filter_or_cow_child(i);
5838 if (child && child->bs->never_freeze) {
5839 error_setg(errp, "Cannot freeze '%s' link to '%s'",
5840 child->name, child->bs->node_name);
5841 return -EPERM;
5845 for (i = bs; i != base; i = child_bs(child)) {
5846 child = bdrv_filter_or_cow_child(i);
5847 if (child) {
5848 child->frozen = true;
5852 return 0;
5856 * Unfreeze all COW (backing) and filter links between @bs and @base.
5857 * The caller must ensure that all links are frozen before using this
5858 * function.
5859 * @base must be reachable from @bs, or NULL.
5861 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
5863 BlockDriverState *i;
5864 BdrvChild *child;
5866 GLOBAL_STATE_CODE();
5868 for (i = bs; i != base; i = child_bs(child)) {
5869 child = bdrv_filter_or_cow_child(i);
5870 if (child) {
5871 assert(child->frozen);
5872 child->frozen = false;
5878 * Drops images above 'base' up to and including 'top', and sets the image
5879 * above 'top' to have base as its backing file.
5881 * Requires that the overlay to 'top' is opened r/w, so that the backing file
5882 * information in 'bs' can be properly updated.
5884 * E.g., this will convert the following chain:
5885 * bottom <- base <- intermediate <- top <- active
5887 * to
5889 * bottom <- base <- active
5891 * It is allowed for bottom==base, in which case it converts:
5893 * base <- intermediate <- top <- active
5895 * to
5897 * base <- active
5899 * If backing_file_str is non-NULL, it will be used when modifying top's
5900 * overlay image metadata.
5902 * Error conditions:
5903 * if active == top, that is considered an error
5906 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
5907 const char *backing_file_str)
5909 BlockDriverState *explicit_top = top;
5910 bool update_inherits_from;
5911 BdrvChild *c;
5912 Error *local_err = NULL;
5913 int ret = -EIO;
5914 g_autoptr(GSList) updated_children = NULL;
5915 GSList *p;
5917 GLOBAL_STATE_CODE();
5919 bdrv_ref(top);
5920 bdrv_drained_begin(base);
5922 if (!top->drv || !base->drv) {
5923 goto exit;
5926 /* Make sure that base is in the backing chain of top */
5927 if (!bdrv_chain_contains(top, base)) {
5928 goto exit;
5931 /* If 'base' recursively inherits from 'top' then we should set
5932 * base->inherits_from to top->inherits_from after 'top' and all
5933 * other intermediate nodes have been dropped.
5934 * If 'top' is an implicit node (e.g. "commit_top") we should skip
5935 * it because no one inherits from it. We use explicit_top for that. */
5936 explicit_top = bdrv_skip_implicit_filters(explicit_top);
5937 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
5939 /* success - we can delete the intermediate states, and link top->base */
5940 if (!backing_file_str) {
5941 bdrv_refresh_filename(base);
5942 backing_file_str = base->filename;
5945 bdrv_graph_rdlock_main_loop();
5946 QLIST_FOREACH(c, &top->parents, next_parent) {
5947 updated_children = g_slist_prepend(updated_children, c);
5949 bdrv_graph_rdunlock_main_loop();
5952 * It seems correct to pass detach_subchain=true here, but it triggers
5953 * one more yet not fixed bug, when due to nested aio_poll loop we switch to
5954 * another drained section, which modify the graph (for example, removing
5955 * the child, which we keep in updated_children list). So, it's a TODO.
5957 * Note, bug triggered if pass detach_subchain=true here and run
5958 * test-bdrv-drain. test_drop_intermediate_poll() test-case will crash.
5959 * That's a FIXME.
5961 bdrv_replace_node_common(top, base, false, false, &local_err);
5962 if (local_err) {
5963 error_report_err(local_err);
5964 goto exit;
5967 for (p = updated_children; p; p = p->next) {
5968 c = p->data;
5970 if (c->klass->update_filename) {
5971 ret = c->klass->update_filename(c, base, backing_file_str,
5972 &local_err);
5973 if (ret < 0) {
5975 * TODO: Actually, we want to rollback all previous iterations
5976 * of this loop, and (which is almost impossible) previous
5977 * bdrv_replace_node()...
5979 * Note, that c->klass->update_filename may lead to permission
5980 * update, so it's a bad idea to call it inside permission
5981 * update transaction of bdrv_replace_node.
5983 error_report_err(local_err);
5984 goto exit;
5989 if (update_inherits_from) {
5990 base->inherits_from = explicit_top->inherits_from;
5993 ret = 0;
5994 exit:
5995 bdrv_drained_end(base);
5996 bdrv_unref(top);
5997 return ret;
6001 * Implementation of BlockDriver.bdrv_co_get_allocated_file_size() that
6002 * sums the size of all data-bearing children. (This excludes backing
6003 * children.)
6005 static int64_t coroutine_fn GRAPH_RDLOCK
6006 bdrv_sum_allocated_file_size(BlockDriverState *bs)
6008 BdrvChild *child;
6009 int64_t child_size, sum = 0;
6011 QLIST_FOREACH(child, &bs->children, next) {
6012 if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
6013 BDRV_CHILD_FILTERED))
6015 child_size = bdrv_co_get_allocated_file_size(child->bs);
6016 if (child_size < 0) {
6017 return child_size;
6019 sum += child_size;
6023 return sum;
6027 * Length of a allocated file in bytes. Sparse files are counted by actual
6028 * allocated space. Return < 0 if error or unknown.
6030 int64_t coroutine_fn bdrv_co_get_allocated_file_size(BlockDriverState *bs)
6032 BlockDriver *drv = bs->drv;
6033 IO_CODE();
6034 assert_bdrv_graph_readable();
6036 if (!drv) {
6037 return -ENOMEDIUM;
6039 if (drv->bdrv_co_get_allocated_file_size) {
6040 return drv->bdrv_co_get_allocated_file_size(bs);
6043 if (drv->bdrv_file_open) {
6045 * Protocol drivers default to -ENOTSUP (most of their data is
6046 * not stored in any of their children (if they even have any),
6047 * so there is no generic way to figure it out).
6049 return -ENOTSUP;
6050 } else if (drv->is_filter) {
6051 /* Filter drivers default to the size of their filtered child */
6052 return bdrv_co_get_allocated_file_size(bdrv_filter_bs(bs));
6053 } else {
6054 /* Other drivers default to summing their children's sizes */
6055 return bdrv_sum_allocated_file_size(bs);
6060 * bdrv_measure:
6061 * @drv: Format driver
6062 * @opts: Creation options for new image
6063 * @in_bs: Existing image containing data for new image (may be NULL)
6064 * @errp: Error object
6065 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
6066 * or NULL on error
6068 * Calculate file size required to create a new image.
6070 * If @in_bs is given then space for allocated clusters and zero clusters
6071 * from that image are included in the calculation. If @opts contains a
6072 * backing file that is shared by @in_bs then backing clusters may be omitted
6073 * from the calculation.
6075 * If @in_bs is NULL then the calculation includes no allocated clusters
6076 * unless a preallocation option is given in @opts.
6078 * Note that @in_bs may use a different BlockDriver from @drv.
6080 * If an error occurs the @errp pointer is set.
6082 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
6083 BlockDriverState *in_bs, Error **errp)
6085 IO_CODE();
6086 if (!drv->bdrv_measure) {
6087 error_setg(errp, "Block driver '%s' does not support size measurement",
6088 drv->format_name);
6089 return NULL;
6092 return drv->bdrv_measure(opts, in_bs, errp);
6096 * Return number of sectors on success, -errno on error.
6098 int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs)
6100 BlockDriver *drv = bs->drv;
6101 IO_CODE();
6102 assert_bdrv_graph_readable();
6104 if (!drv)
6105 return -ENOMEDIUM;
6107 if (bs->bl.has_variable_length) {
6108 int ret = bdrv_co_refresh_total_sectors(bs, bs->total_sectors);
6109 if (ret < 0) {
6110 return ret;
6113 return bs->total_sectors;
6117 * This wrapper is written by hand because this function is in the hot I/O path,
6118 * via blk_get_geometry.
6120 int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs)
6122 BlockDriver *drv = bs->drv;
6123 IO_CODE();
6125 if (!drv)
6126 return -ENOMEDIUM;
6128 if (bs->bl.has_variable_length) {
6129 int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
6130 if (ret < 0) {
6131 return ret;
6135 return bs->total_sectors;
6139 * Return length in bytes on success, -errno on error.
6140 * The length is always a multiple of BDRV_SECTOR_SIZE.
6142 int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs)
6144 int64_t ret;
6145 IO_CODE();
6146 assert_bdrv_graph_readable();
6148 ret = bdrv_co_nb_sectors(bs);
6149 if (ret < 0) {
6150 return ret;
6152 if (ret > INT64_MAX / BDRV_SECTOR_SIZE) {
6153 return -EFBIG;
6155 return ret * BDRV_SECTOR_SIZE;
6158 bool bdrv_is_sg(BlockDriverState *bs)
6160 IO_CODE();
6161 return bs->sg;
6165 * Return whether the given node supports compressed writes.
6167 bool bdrv_supports_compressed_writes(BlockDriverState *bs)
6169 BlockDriverState *filtered;
6170 IO_CODE();
6172 if (!bs->drv || !block_driver_can_compress(bs->drv)) {
6173 return false;
6176 filtered = bdrv_filter_bs(bs);
6177 if (filtered) {
6179 * Filters can only forward compressed writes, so we have to
6180 * check the child.
6182 return bdrv_supports_compressed_writes(filtered);
6185 return true;
6188 const char *bdrv_get_format_name(BlockDriverState *bs)
6190 IO_CODE();
6191 return bs->drv ? bs->drv->format_name : NULL;
6194 static int qsort_strcmp(const void *a, const void *b)
6196 return strcmp(*(char *const *)a, *(char *const *)b);
6199 void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
6200 void *opaque, bool read_only)
6202 BlockDriver *drv;
6203 int count = 0;
6204 int i;
6205 const char **formats = NULL;
6207 GLOBAL_STATE_CODE();
6209 QLIST_FOREACH(drv, &bdrv_drivers, list) {
6210 if (drv->format_name) {
6211 bool found = false;
6213 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) {
6214 continue;
6217 i = count;
6218 while (formats && i && !found) {
6219 found = !strcmp(formats[--i], drv->format_name);
6222 if (!found) {
6223 formats = g_renew(const char *, formats, count + 1);
6224 formats[count++] = drv->format_name;
6229 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) {
6230 const char *format_name = block_driver_modules[i].format_name;
6232 if (format_name) {
6233 bool found = false;
6234 int j = count;
6236 if (use_bdrv_whitelist &&
6237 !bdrv_format_is_whitelisted(format_name, read_only)) {
6238 continue;
6241 while (formats && j && !found) {
6242 found = !strcmp(formats[--j], format_name);
6245 if (!found) {
6246 formats = g_renew(const char *, formats, count + 1);
6247 formats[count++] = format_name;
6252 qsort(formats, count, sizeof(formats[0]), qsort_strcmp);
6254 for (i = 0; i < count; i++) {
6255 it(opaque, formats[i]);
6258 g_free(formats);
6261 /* This function is to find a node in the bs graph */
6262 BlockDriverState *bdrv_find_node(const char *node_name)
6264 BlockDriverState *bs;
6266 assert(node_name);
6267 GLOBAL_STATE_CODE();
6269 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
6270 if (!strcmp(node_name, bs->node_name)) {
6271 return bs;
6274 return NULL;
6277 /* Put this QMP function here so it can access the static graph_bdrv_states. */
6278 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
6279 Error **errp)
6281 BlockDeviceInfoList *list;
6282 BlockDriverState *bs;
6284 GLOBAL_STATE_CODE();
6286 list = NULL;
6287 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
6288 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
6289 if (!info) {
6290 qapi_free_BlockDeviceInfoList(list);
6291 return NULL;
6293 QAPI_LIST_PREPEND(list, info);
6296 return list;
6299 typedef struct XDbgBlockGraphConstructor {
6300 XDbgBlockGraph *graph;
6301 GHashTable *graph_nodes;
6302 } XDbgBlockGraphConstructor;
6304 static XDbgBlockGraphConstructor *xdbg_graph_new(void)
6306 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1);
6308 gr->graph = g_new0(XDbgBlockGraph, 1);
6309 gr->graph_nodes = g_hash_table_new(NULL, NULL);
6311 return gr;
6314 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr)
6316 XDbgBlockGraph *graph = gr->graph;
6318 g_hash_table_destroy(gr->graph_nodes);
6319 g_free(gr);
6321 return graph;
6324 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node)
6326 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node);
6328 if (ret != 0) {
6329 return ret;
6333 * Start counting from 1, not 0, because 0 interferes with not-found (NULL)
6334 * answer of g_hash_table_lookup.
6336 ret = g_hash_table_size(gr->graph_nodes) + 1;
6337 g_hash_table_insert(gr->graph_nodes, node, (void *)ret);
6339 return ret;
6342 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node,
6343 XDbgBlockGraphNodeType type, const char *name)
6345 XDbgBlockGraphNode *n;
6347 n = g_new0(XDbgBlockGraphNode, 1);
6349 n->id = xdbg_graph_node_num(gr, node);
6350 n->type = type;
6351 n->name = g_strdup(name);
6353 QAPI_LIST_PREPEND(gr->graph->nodes, n);
6356 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent,
6357 const BdrvChild *child)
6359 BlockPermission qapi_perm;
6360 XDbgBlockGraphEdge *edge;
6361 GLOBAL_STATE_CODE();
6363 edge = g_new0(XDbgBlockGraphEdge, 1);
6365 edge->parent = xdbg_graph_node_num(gr, parent);
6366 edge->child = xdbg_graph_node_num(gr, child->bs);
6367 edge->name = g_strdup(child->name);
6369 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) {
6370 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm);
6372 if (flag & child->perm) {
6373 QAPI_LIST_PREPEND(edge->perm, qapi_perm);
6375 if (flag & child->shared_perm) {
6376 QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm);
6380 QAPI_LIST_PREPEND(gr->graph->edges, edge);
6384 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp)
6386 BlockBackend *blk;
6387 BlockJob *job;
6388 BlockDriverState *bs;
6389 BdrvChild *child;
6390 XDbgBlockGraphConstructor *gr = xdbg_graph_new();
6392 GLOBAL_STATE_CODE();
6394 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
6395 char *allocated_name = NULL;
6396 const char *name = blk_name(blk);
6398 if (!*name) {
6399 name = allocated_name = blk_get_attached_dev_id(blk);
6401 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND,
6402 name);
6403 g_free(allocated_name);
6404 if (blk_root(blk)) {
6405 xdbg_graph_add_edge(gr, blk, blk_root(blk));
6409 WITH_JOB_LOCK_GUARD() {
6410 for (job = block_job_next_locked(NULL); job;
6411 job = block_job_next_locked(job)) {
6412 GSList *el;
6414 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB,
6415 job->job.id);
6416 for (el = job->nodes; el; el = el->next) {
6417 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data);
6422 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
6423 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER,
6424 bs->node_name);
6425 QLIST_FOREACH(child, &bs->children, next) {
6426 xdbg_graph_add_edge(gr, bs, child);
6430 return xdbg_graph_finalize(gr);
6433 BlockDriverState *bdrv_lookup_bs(const char *device,
6434 const char *node_name,
6435 Error **errp)
6437 BlockBackend *blk;
6438 BlockDriverState *bs;
6440 GLOBAL_STATE_CODE();
6442 if (device) {
6443 blk = blk_by_name(device);
6445 if (blk) {
6446 bs = blk_bs(blk);
6447 if (!bs) {
6448 error_setg(errp, "Device '%s' has no medium", device);
6451 return bs;
6455 if (node_name) {
6456 bs = bdrv_find_node(node_name);
6458 if (bs) {
6459 return bs;
6463 error_setg(errp, "Cannot find device=\'%s\' nor node-name=\'%s\'",
6464 device ? device : "",
6465 node_name ? node_name : "");
6466 return NULL;
6469 /* If 'base' is in the same chain as 'top', return true. Otherwise,
6470 * return false. If either argument is NULL, return false. */
6471 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
6474 GLOBAL_STATE_CODE();
6476 while (top && top != base) {
6477 top = bdrv_filter_or_cow_bs(top);
6480 return top != NULL;
6483 BlockDriverState *bdrv_next_node(BlockDriverState *bs)
6485 GLOBAL_STATE_CODE();
6486 if (!bs) {
6487 return QTAILQ_FIRST(&graph_bdrv_states);
6489 return QTAILQ_NEXT(bs, node_list);
6492 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs)
6494 GLOBAL_STATE_CODE();
6495 if (!bs) {
6496 return QTAILQ_FIRST(&all_bdrv_states);
6498 return QTAILQ_NEXT(bs, bs_list);
6501 const char *bdrv_get_node_name(const BlockDriverState *bs)
6503 IO_CODE();
6504 return bs->node_name;
6507 const char *bdrv_get_parent_name(const BlockDriverState *bs)
6509 BdrvChild *c;
6510 const char *name;
6511 IO_CODE();
6513 /* If multiple parents have a name, just pick the first one. */
6514 QLIST_FOREACH(c, &bs->parents, next_parent) {
6515 if (c->klass->get_name) {
6516 name = c->klass->get_name(c);
6517 if (name && *name) {
6518 return name;
6523 return NULL;
6526 /* TODO check what callers really want: bs->node_name or blk_name() */
6527 const char *bdrv_get_device_name(const BlockDriverState *bs)
6529 IO_CODE();
6530 return bdrv_get_parent_name(bs) ?: "";
6533 /* This can be used to identify nodes that might not have a device
6534 * name associated. Since node and device names live in the same
6535 * namespace, the result is unambiguous. The exception is if both are
6536 * absent, then this returns an empty (non-null) string. */
6537 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
6539 IO_CODE();
6540 return bdrv_get_parent_name(bs) ?: bs->node_name;
6543 int bdrv_get_flags(BlockDriverState *bs)
6545 IO_CODE();
6546 return bs->open_flags;
6549 int bdrv_has_zero_init_1(BlockDriverState *bs)
6551 GLOBAL_STATE_CODE();
6552 return 1;
6555 int bdrv_has_zero_init(BlockDriverState *bs)
6557 BlockDriverState *filtered;
6558 GLOBAL_STATE_CODE();
6560 if (!bs->drv) {
6561 return 0;
6564 /* If BS is a copy on write image, it is initialized to
6565 the contents of the base image, which may not be zeroes. */
6566 if (bdrv_cow_child(bs)) {
6567 return 0;
6569 if (bs->drv->bdrv_has_zero_init) {
6570 return bs->drv->bdrv_has_zero_init(bs);
6573 filtered = bdrv_filter_bs(bs);
6574 if (filtered) {
6575 return bdrv_has_zero_init(filtered);
6578 /* safe default */
6579 return 0;
6582 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
6584 IO_CODE();
6585 if (!(bs->open_flags & BDRV_O_UNMAP)) {
6586 return false;
6589 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
6592 void bdrv_get_backing_filename(BlockDriverState *bs,
6593 char *filename, int filename_size)
6595 IO_CODE();
6596 pstrcpy(filename, filename_size, bs->backing_file);
6599 int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
6601 int ret;
6602 BlockDriver *drv = bs->drv;
6603 IO_CODE();
6604 assert_bdrv_graph_readable();
6606 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
6607 if (!drv) {
6608 return -ENOMEDIUM;
6610 if (!drv->bdrv_co_get_info) {
6611 BlockDriverState *filtered = bdrv_filter_bs(bs);
6612 if (filtered) {
6613 return bdrv_co_get_info(filtered, bdi);
6615 return -ENOTSUP;
6617 memset(bdi, 0, sizeof(*bdi));
6618 ret = drv->bdrv_co_get_info(bs, bdi);
6619 if (bdi->subcluster_size == 0) {
6621 * If the driver left this unset, subclusters are not supported.
6622 * Then it is safe to treat each cluster as having only one subcluster.
6624 bdi->subcluster_size = bdi->cluster_size;
6626 if (ret < 0) {
6627 return ret;
6630 if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) {
6631 return -EINVAL;
6634 return 0;
6637 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
6638 Error **errp)
6640 BlockDriver *drv = bs->drv;
6641 IO_CODE();
6642 if (drv && drv->bdrv_get_specific_info) {
6643 return drv->bdrv_get_specific_info(bs, errp);
6645 return NULL;
6648 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs)
6650 BlockDriver *drv = bs->drv;
6651 IO_CODE();
6652 if (!drv || !drv->bdrv_get_specific_stats) {
6653 return NULL;
6655 return drv->bdrv_get_specific_stats(bs);
6658 void coroutine_fn bdrv_co_debug_event(BlockDriverState *bs, BlkdebugEvent event)
6660 IO_CODE();
6661 assert_bdrv_graph_readable();
6663 if (!bs || !bs->drv || !bs->drv->bdrv_co_debug_event) {
6664 return;
6667 bs->drv->bdrv_co_debug_event(bs, event);
6670 static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs)
6672 GLOBAL_STATE_CODE();
6673 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
6674 bs = bdrv_primary_bs(bs);
6677 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
6678 assert(bs->drv->bdrv_debug_remove_breakpoint);
6679 return bs;
6682 return NULL;
6685 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event,
6686 const char *tag)
6688 GLOBAL_STATE_CODE();
6689 bs = bdrv_find_debug_node(bs);
6690 if (bs) {
6691 return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
6694 return -ENOTSUP;
6697 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
6699 GLOBAL_STATE_CODE();
6700 bs = bdrv_find_debug_node(bs);
6701 if (bs) {
6702 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
6705 return -ENOTSUP;
6708 int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
6710 GLOBAL_STATE_CODE();
6711 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
6712 bs = bdrv_primary_bs(bs);
6715 if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
6716 return bs->drv->bdrv_debug_resume(bs, tag);
6719 return -ENOTSUP;
6722 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
6724 GLOBAL_STATE_CODE();
6725 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
6726 bs = bdrv_primary_bs(bs);
6729 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
6730 return bs->drv->bdrv_debug_is_suspended(bs, tag);
6733 return false;
6736 /* backing_file can either be relative, or absolute, or a protocol. If it is
6737 * relative, it must be relative to the chain. So, passing in bs->filename
6738 * from a BDS as backing_file should not be done, as that may be relative to
6739 * the CWD rather than the chain. */
6740 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
6741 const char *backing_file)
6743 char *filename_full = NULL;
6744 char *backing_file_full = NULL;
6745 char *filename_tmp = NULL;
6746 int is_protocol = 0;
6747 bool filenames_refreshed = false;
6748 BlockDriverState *curr_bs = NULL;
6749 BlockDriverState *retval = NULL;
6750 BlockDriverState *bs_below;
6752 GLOBAL_STATE_CODE();
6754 if (!bs || !bs->drv || !backing_file) {
6755 return NULL;
6758 filename_full = g_malloc(PATH_MAX);
6759 backing_file_full = g_malloc(PATH_MAX);
6761 is_protocol = path_has_protocol(backing_file);
6764 * Being largely a legacy function, skip any filters here
6765 * (because filters do not have normal filenames, so they cannot
6766 * match anyway; and allowing json:{} filenames is a bit out of
6767 * scope).
6769 for (curr_bs = bdrv_skip_filters(bs);
6770 bdrv_cow_child(curr_bs) != NULL;
6771 curr_bs = bs_below)
6773 bs_below = bdrv_backing_chain_next(curr_bs);
6775 if (bdrv_backing_overridden(curr_bs)) {
6777 * If the backing file was overridden, we can only compare
6778 * directly against the backing node's filename.
6781 if (!filenames_refreshed) {
6783 * This will automatically refresh all of the
6784 * filenames in the rest of the backing chain, so we
6785 * only need to do this once.
6787 bdrv_refresh_filename(bs_below);
6788 filenames_refreshed = true;
6791 if (strcmp(backing_file, bs_below->filename) == 0) {
6792 retval = bs_below;
6793 break;
6795 } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
6797 * If either of the filename paths is actually a protocol, then
6798 * compare unmodified paths; otherwise make paths relative.
6800 char *backing_file_full_ret;
6802 if (strcmp(backing_file, curr_bs->backing_file) == 0) {
6803 retval = bs_below;
6804 break;
6806 /* Also check against the full backing filename for the image */
6807 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs,
6808 NULL);
6809 if (backing_file_full_ret) {
6810 bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
6811 g_free(backing_file_full_ret);
6812 if (equal) {
6813 retval = bs_below;
6814 break;
6817 } else {
6818 /* If not an absolute filename path, make it relative to the current
6819 * image's filename path */
6820 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
6821 NULL);
6822 /* We are going to compare canonicalized absolute pathnames */
6823 if (!filename_tmp || !realpath(filename_tmp, filename_full)) {
6824 g_free(filename_tmp);
6825 continue;
6827 g_free(filename_tmp);
6829 /* We need to make sure the backing filename we are comparing against
6830 * is relative to the current image filename (or absolute) */
6831 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
6832 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) {
6833 g_free(filename_tmp);
6834 continue;
6836 g_free(filename_tmp);
6838 if (strcmp(backing_file_full, filename_full) == 0) {
6839 retval = bs_below;
6840 break;
6845 g_free(filename_full);
6846 g_free(backing_file_full);
6847 return retval;
6850 void bdrv_init(void)
6852 #ifdef CONFIG_BDRV_WHITELIST_TOOLS
6853 use_bdrv_whitelist = 1;
6854 #endif
6855 module_call_init(MODULE_INIT_BLOCK);
6858 void bdrv_init_with_whitelist(void)
6860 use_bdrv_whitelist = 1;
6861 bdrv_init();
6864 int bdrv_activate(BlockDriverState *bs, Error **errp)
6866 BdrvChild *child, *parent;
6867 Error *local_err = NULL;
6868 int ret;
6869 BdrvDirtyBitmap *bm;
6871 GLOBAL_STATE_CODE();
6872 GRAPH_RDLOCK_GUARD_MAINLOOP();
6874 if (!bs->drv) {
6875 return -ENOMEDIUM;
6878 QLIST_FOREACH(child, &bs->children, next) {
6879 bdrv_activate(child->bs, &local_err);
6880 if (local_err) {
6881 error_propagate(errp, local_err);
6882 return -EINVAL;
6887 * Update permissions, they may differ for inactive nodes.
6889 * Note that the required permissions of inactive images are always a
6890 * subset of the permissions required after activating the image. This
6891 * allows us to just get the permissions upfront without restricting
6892 * bdrv_co_invalidate_cache().
6894 * It also means that in error cases, we don't have to try and revert to
6895 * the old permissions (which is an operation that could fail, too). We can
6896 * just keep the extended permissions for the next time that an activation
6897 * of the image is tried.
6899 if (bs->open_flags & BDRV_O_INACTIVE) {
6900 bs->open_flags &= ~BDRV_O_INACTIVE;
6901 ret = bdrv_refresh_perms(bs, NULL, errp);
6902 if (ret < 0) {
6903 bs->open_flags |= BDRV_O_INACTIVE;
6904 return ret;
6907 ret = bdrv_invalidate_cache(bs, errp);
6908 if (ret < 0) {
6909 bs->open_flags |= BDRV_O_INACTIVE;
6910 return ret;
6913 FOR_EACH_DIRTY_BITMAP(bs, bm) {
6914 bdrv_dirty_bitmap_skip_store(bm, false);
6917 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
6918 if (ret < 0) {
6919 bs->open_flags |= BDRV_O_INACTIVE;
6920 error_setg_errno(errp, -ret, "Could not refresh total sector count");
6921 return ret;
6925 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6926 if (parent->klass->activate) {
6927 parent->klass->activate(parent, &local_err);
6928 if (local_err) {
6929 bs->open_flags |= BDRV_O_INACTIVE;
6930 error_propagate(errp, local_err);
6931 return -EINVAL;
6936 return 0;
6939 int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp)
6941 Error *local_err = NULL;
6942 IO_CODE();
6944 assert(!(bs->open_flags & BDRV_O_INACTIVE));
6945 assert_bdrv_graph_readable();
6947 if (bs->drv->bdrv_co_invalidate_cache) {
6948 bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
6949 if (local_err) {
6950 error_propagate(errp, local_err);
6951 return -EINVAL;
6955 return 0;
6958 void bdrv_activate_all(Error **errp)
6960 BlockDriverState *bs;
6961 BdrvNextIterator it;
6963 GLOBAL_STATE_CODE();
6964 GRAPH_RDLOCK_GUARD_MAINLOOP();
6966 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
6967 AioContext *aio_context = bdrv_get_aio_context(bs);
6968 int ret;
6970 aio_context_acquire(aio_context);
6971 ret = bdrv_activate(bs, errp);
6972 aio_context_release(aio_context);
6973 if (ret < 0) {
6974 bdrv_next_cleanup(&it);
6975 return;
6980 static bool GRAPH_RDLOCK
6981 bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
6983 BdrvChild *parent;
6984 GLOBAL_STATE_CODE();
6986 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6987 if (parent->klass->parent_is_bds) {
6988 BlockDriverState *parent_bs = parent->opaque;
6989 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) {
6990 return true;
6995 return false;
6998 static int GRAPH_RDLOCK bdrv_inactivate_recurse(BlockDriverState *bs)
7000 BdrvChild *child, *parent;
7001 int ret;
7002 uint64_t cumulative_perms, cumulative_shared_perms;
7004 GLOBAL_STATE_CODE();
7006 if (!bs->drv) {
7007 return -ENOMEDIUM;
7010 /* Make sure that we don't inactivate a child before its parent.
7011 * It will be covered by recursion from the yet active parent. */
7012 if (bdrv_has_bds_parent(bs, true)) {
7013 return 0;
7016 assert(!(bs->open_flags & BDRV_O_INACTIVE));
7018 /* Inactivate this node */
7019 if (bs->drv->bdrv_inactivate) {
7020 ret = bs->drv->bdrv_inactivate(bs);
7021 if (ret < 0) {
7022 return ret;
7026 QLIST_FOREACH(parent, &bs->parents, next_parent) {
7027 if (parent->klass->inactivate) {
7028 ret = parent->klass->inactivate(parent);
7029 if (ret < 0) {
7030 return ret;
7035 bdrv_get_cumulative_perm(bs, &cumulative_perms,
7036 &cumulative_shared_perms);
7037 if (cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
7038 /* Our inactive parents still need write access. Inactivation failed. */
7039 return -EPERM;
7042 bs->open_flags |= BDRV_O_INACTIVE;
7045 * Update permissions, they may differ for inactive nodes.
7046 * We only tried to loosen restrictions, so errors are not fatal, ignore
7047 * them.
7049 bdrv_refresh_perms(bs, NULL, NULL);
7051 /* Recursively inactivate children */
7052 QLIST_FOREACH(child, &bs->children, next) {
7053 ret = bdrv_inactivate_recurse(child->bs);
7054 if (ret < 0) {
7055 return ret;
7059 return 0;
7062 int bdrv_inactivate_all(void)
7064 BlockDriverState *bs = NULL;
7065 BdrvNextIterator it;
7066 int ret = 0;
7067 GSList *aio_ctxs = NULL, *ctx;
7069 GLOBAL_STATE_CODE();
7070 GRAPH_RDLOCK_GUARD_MAINLOOP();
7072 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
7073 AioContext *aio_context = bdrv_get_aio_context(bs);
7075 if (!g_slist_find(aio_ctxs, aio_context)) {
7076 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
7077 aio_context_acquire(aio_context);
7081 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
7082 /* Nodes with BDS parents are covered by recursion from the last
7083 * parent that gets inactivated. Don't inactivate them a second
7084 * time if that has already happened. */
7085 if (bdrv_has_bds_parent(bs, false)) {
7086 continue;
7088 ret = bdrv_inactivate_recurse(bs);
7089 if (ret < 0) {
7090 bdrv_next_cleanup(&it);
7091 goto out;
7095 out:
7096 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
7097 AioContext *aio_context = ctx->data;
7098 aio_context_release(aio_context);
7100 g_slist_free(aio_ctxs);
7102 return ret;
7105 /**************************************************************/
7106 /* removable device support */
7109 * Return TRUE if the media is present
7111 bool coroutine_fn bdrv_co_is_inserted(BlockDriverState *bs)
7113 BlockDriver *drv = bs->drv;
7114 BdrvChild *child;
7115 IO_CODE();
7116 assert_bdrv_graph_readable();
7118 if (!drv) {
7119 return false;
7121 if (drv->bdrv_co_is_inserted) {
7122 return drv->bdrv_co_is_inserted(bs);
7124 QLIST_FOREACH(child, &bs->children, next) {
7125 if (!bdrv_co_is_inserted(child->bs)) {
7126 return false;
7129 return true;
7133 * If eject_flag is TRUE, eject the media. Otherwise, close the tray
7135 void coroutine_fn bdrv_co_eject(BlockDriverState *bs, bool eject_flag)
7137 BlockDriver *drv = bs->drv;
7138 IO_CODE();
7139 assert_bdrv_graph_readable();
7141 if (drv && drv->bdrv_co_eject) {
7142 drv->bdrv_co_eject(bs, eject_flag);
7147 * Lock or unlock the media (if it is locked, the user won't be able
7148 * to eject it manually).
7150 void coroutine_fn bdrv_co_lock_medium(BlockDriverState *bs, bool locked)
7152 BlockDriver *drv = bs->drv;
7153 IO_CODE();
7154 assert_bdrv_graph_readable();
7155 trace_bdrv_lock_medium(bs, locked);
7157 if (drv && drv->bdrv_co_lock_medium) {
7158 drv->bdrv_co_lock_medium(bs, locked);
7162 /* Get a reference to bs */
7163 void bdrv_ref(BlockDriverState *bs)
7165 GLOBAL_STATE_CODE();
7166 bs->refcnt++;
7169 /* Release a previously grabbed reference to bs.
7170 * If after releasing, reference count is zero, the BlockDriverState is
7171 * deleted. */
7172 void bdrv_unref(BlockDriverState *bs)
7174 GLOBAL_STATE_CODE();
7175 if (!bs) {
7176 return;
7178 assert(bs->refcnt > 0);
7179 if (--bs->refcnt == 0) {
7180 bdrv_delete(bs);
7185 * Release a BlockDriverState reference while holding the graph write lock.
7187 * Calling bdrv_unref() directly is forbidden while holding the graph lock
7188 * because bdrv_close() both involves polling and taking the graph lock
7189 * internally. bdrv_schedule_unref() instead delays decreasing the refcount and
7190 * possibly closing @bs until the graph lock is released.
7192 void bdrv_schedule_unref(BlockDriverState *bs)
7194 if (!bs) {
7195 return;
7197 aio_bh_schedule_oneshot(qemu_get_aio_context(),
7198 (QEMUBHFunc *) bdrv_unref, bs);
7201 struct BdrvOpBlocker {
7202 Error *reason;
7203 QLIST_ENTRY(BdrvOpBlocker) list;
7206 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
7208 BdrvOpBlocker *blocker;
7209 GLOBAL_STATE_CODE();
7210 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
7211 if (!QLIST_EMPTY(&bs->op_blockers[op])) {
7212 blocker = QLIST_FIRST(&bs->op_blockers[op]);
7213 error_propagate_prepend(errp, error_copy(blocker->reason),
7214 "Node '%s' is busy: ",
7215 bdrv_get_device_or_node_name(bs));
7216 return true;
7218 return false;
7221 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
7223 BdrvOpBlocker *blocker;
7224 GLOBAL_STATE_CODE();
7225 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
7227 blocker = g_new0(BdrvOpBlocker, 1);
7228 blocker->reason = reason;
7229 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
7232 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
7234 BdrvOpBlocker *blocker, *next;
7235 GLOBAL_STATE_CODE();
7236 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
7237 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
7238 if (blocker->reason == reason) {
7239 QLIST_REMOVE(blocker, list);
7240 g_free(blocker);
7245 void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
7247 int i;
7248 GLOBAL_STATE_CODE();
7249 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
7250 bdrv_op_block(bs, i, reason);
7254 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
7256 int i;
7257 GLOBAL_STATE_CODE();
7258 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
7259 bdrv_op_unblock(bs, i, reason);
7263 bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
7265 int i;
7266 GLOBAL_STATE_CODE();
7267 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
7268 if (!QLIST_EMPTY(&bs->op_blockers[i])) {
7269 return false;
7272 return true;
7276 * Must not be called while holding the lock of an AioContext other than the
7277 * current one.
7279 void bdrv_img_create(const char *filename, const char *fmt,
7280 const char *base_filename, const char *base_fmt,
7281 char *options, uint64_t img_size, int flags, bool quiet,
7282 Error **errp)
7284 QemuOptsList *create_opts = NULL;
7285 QemuOpts *opts = NULL;
7286 const char *backing_fmt, *backing_file;
7287 int64_t size;
7288 BlockDriver *drv, *proto_drv;
7289 Error *local_err = NULL;
7290 int ret = 0;
7292 GLOBAL_STATE_CODE();
7294 /* Find driver and parse its options */
7295 drv = bdrv_find_format(fmt);
7296 if (!drv) {
7297 error_setg(errp, "Unknown file format '%s'", fmt);
7298 return;
7301 proto_drv = bdrv_find_protocol(filename, true, errp);
7302 if (!proto_drv) {
7303 return;
7306 if (!drv->create_opts) {
7307 error_setg(errp, "Format driver '%s' does not support image creation",
7308 drv->format_name);
7309 return;
7312 if (!proto_drv->create_opts) {
7313 error_setg(errp, "Protocol driver '%s' does not support image creation",
7314 proto_drv->format_name);
7315 return;
7318 aio_context_acquire(qemu_get_aio_context());
7320 /* Create parameter list */
7321 create_opts = qemu_opts_append(create_opts, drv->create_opts);
7322 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
7324 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
7326 /* Parse -o options */
7327 if (options) {
7328 if (!qemu_opts_do_parse(opts, options, NULL, errp)) {
7329 goto out;
7333 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) {
7334 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort);
7335 } else if (img_size != UINT64_C(-1)) {
7336 error_setg(errp, "The image size must be specified only once");
7337 goto out;
7340 if (base_filename) {
7341 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename,
7342 NULL)) {
7343 error_setg(errp, "Backing file not supported for file format '%s'",
7344 fmt);
7345 goto out;
7349 if (base_fmt) {
7350 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) {
7351 error_setg(errp, "Backing file format not supported for file "
7352 "format '%s'", fmt);
7353 goto out;
7357 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
7358 if (backing_file) {
7359 if (!strcmp(filename, backing_file)) {
7360 error_setg(errp, "Error: Trying to create an image with the "
7361 "same filename as the backing file");
7362 goto out;
7364 if (backing_file[0] == '\0') {
7365 error_setg(errp, "Expected backing file name, got empty string");
7366 goto out;
7370 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
7372 /* The size for the image must always be specified, unless we have a backing
7373 * file and we have not been forbidden from opening it. */
7374 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
7375 if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
7376 BlockDriverState *bs;
7377 char *full_backing;
7378 int back_flags;
7379 QDict *backing_options = NULL;
7381 full_backing =
7382 bdrv_get_full_backing_filename_from_filename(filename, backing_file,
7383 &local_err);
7384 if (local_err) {
7385 goto out;
7387 assert(full_backing);
7390 * No need to do I/O here, which allows us to open encrypted
7391 * backing images without needing the secret
7393 back_flags = flags;
7394 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
7395 back_flags |= BDRV_O_NO_IO;
7397 backing_options = qdict_new();
7398 if (backing_fmt) {
7399 qdict_put_str(backing_options, "driver", backing_fmt);
7401 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
7403 bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
7404 &local_err);
7405 g_free(full_backing);
7406 if (!bs) {
7407 error_append_hint(&local_err, "Could not open backing image.\n");
7408 goto out;
7409 } else {
7410 if (!backing_fmt) {
7411 error_setg(&local_err,
7412 "Backing file specified without backing format");
7413 error_append_hint(&local_err, "Detected format of %s.\n",
7414 bs->drv->format_name);
7415 goto out;
7417 if (size == -1) {
7418 /* Opened BS, have no size */
7419 size = bdrv_getlength(bs);
7420 if (size < 0) {
7421 error_setg_errno(errp, -size, "Could not get size of '%s'",
7422 backing_file);
7423 bdrv_unref(bs);
7424 goto out;
7426 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
7428 bdrv_unref(bs);
7430 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
7431 } else if (backing_file && !backing_fmt) {
7432 error_setg(&local_err,
7433 "Backing file specified without backing format");
7434 goto out;
7437 if (size == -1) {
7438 error_setg(errp, "Image creation needs a size parameter");
7439 goto out;
7442 if (!quiet) {
7443 printf("Formatting '%s', fmt=%s ", filename, fmt);
7444 qemu_opts_print(opts, " ");
7445 puts("");
7446 fflush(stdout);
7449 ret = bdrv_create(drv, filename, opts, &local_err);
7451 if (ret == -EFBIG) {
7452 /* This is generally a better message than whatever the driver would
7453 * deliver (especially because of the cluster_size_hint), since that
7454 * is most probably not much different from "image too large". */
7455 const char *cluster_size_hint = "";
7456 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) {
7457 cluster_size_hint = " (try using a larger cluster size)";
7459 error_setg(errp, "The image size is too large for file format '%s'"
7460 "%s", fmt, cluster_size_hint);
7461 error_free(local_err);
7462 local_err = NULL;
7465 out:
7466 qemu_opts_del(opts);
7467 qemu_opts_free(create_opts);
7468 error_propagate(errp, local_err);
7469 aio_context_release(qemu_get_aio_context());
7472 AioContext *bdrv_get_aio_context(BlockDriverState *bs)
7474 IO_CODE();
7475 return bs ? bs->aio_context : qemu_get_aio_context();
7478 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs)
7480 Coroutine *self = qemu_coroutine_self();
7481 AioContext *old_ctx = qemu_coroutine_get_aio_context(self);
7482 AioContext *new_ctx;
7483 IO_CODE();
7486 * Increase bs->in_flight to ensure that this operation is completed before
7487 * moving the node to a different AioContext. Read new_ctx only afterwards.
7489 bdrv_inc_in_flight(bs);
7491 new_ctx = bdrv_get_aio_context(bs);
7492 aio_co_reschedule_self(new_ctx);
7493 return old_ctx;
7496 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx)
7498 IO_CODE();
7499 aio_co_reschedule_self(old_ctx);
7500 bdrv_dec_in_flight(bs);
7503 void coroutine_fn bdrv_co_lock(BlockDriverState *bs)
7505 AioContext *ctx = bdrv_get_aio_context(bs);
7507 /* In the main thread, bs->aio_context won't change concurrently */
7508 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
7511 * We're in coroutine context, so we already hold the lock of the main
7512 * loop AioContext. Don't lock it twice to avoid deadlocks.
7514 assert(qemu_in_coroutine());
7515 if (ctx != qemu_get_aio_context()) {
7516 aio_context_acquire(ctx);
7520 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs)
7522 AioContext *ctx = bdrv_get_aio_context(bs);
7524 assert(qemu_in_coroutine());
7525 if (ctx != qemu_get_aio_context()) {
7526 aio_context_release(ctx);
7530 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
7532 GLOBAL_STATE_CODE();
7533 QLIST_REMOVE(ban, list);
7534 g_free(ban);
7537 static void bdrv_detach_aio_context(BlockDriverState *bs)
7539 BdrvAioNotifier *baf, *baf_tmp;
7541 assert(!bs->walking_aio_notifiers);
7542 GLOBAL_STATE_CODE();
7543 bs->walking_aio_notifiers = true;
7544 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
7545 if (baf->deleted) {
7546 bdrv_do_remove_aio_context_notifier(baf);
7547 } else {
7548 baf->detach_aio_context(baf->opaque);
7551 /* Never mind iterating again to check for ->deleted. bdrv_close() will
7552 * remove remaining aio notifiers if we aren't called again.
7554 bs->walking_aio_notifiers = false;
7556 if (bs->drv && bs->drv->bdrv_detach_aio_context) {
7557 bs->drv->bdrv_detach_aio_context(bs);
7560 bs->aio_context = NULL;
7563 static void bdrv_attach_aio_context(BlockDriverState *bs,
7564 AioContext *new_context)
7566 BdrvAioNotifier *ban, *ban_tmp;
7567 GLOBAL_STATE_CODE();
7569 bs->aio_context = new_context;
7571 if (bs->drv && bs->drv->bdrv_attach_aio_context) {
7572 bs->drv->bdrv_attach_aio_context(bs, new_context);
7575 assert(!bs->walking_aio_notifiers);
7576 bs->walking_aio_notifiers = true;
7577 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) {
7578 if (ban->deleted) {
7579 bdrv_do_remove_aio_context_notifier(ban);
7580 } else {
7581 ban->attached_aio_context(new_context, ban->opaque);
7584 bs->walking_aio_notifiers = false;
7587 typedef struct BdrvStateSetAioContext {
7588 AioContext *new_ctx;
7589 BlockDriverState *bs;
7590 } BdrvStateSetAioContext;
7592 static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx,
7593 GHashTable *visited,
7594 Transaction *tran,
7595 Error **errp)
7597 GLOBAL_STATE_CODE();
7598 if (g_hash_table_contains(visited, c)) {
7599 return true;
7601 g_hash_table_add(visited, c);
7604 * A BdrvChildClass that doesn't handle AioContext changes cannot
7605 * tolerate any AioContext changes
7607 if (!c->klass->change_aio_ctx) {
7608 char *user = bdrv_child_user_desc(c);
7609 error_setg(errp, "Changing iothreads is not supported by %s", user);
7610 g_free(user);
7611 return false;
7613 if (!c->klass->change_aio_ctx(c, ctx, visited, tran, errp)) {
7614 assert(!errp || *errp);
7615 return false;
7617 return true;
7620 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
7621 GHashTable *visited, Transaction *tran,
7622 Error **errp)
7624 GLOBAL_STATE_CODE();
7625 if (g_hash_table_contains(visited, c)) {
7626 return true;
7628 g_hash_table_add(visited, c);
7629 return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp);
7632 static void bdrv_set_aio_context_clean(void *opaque)
7634 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
7635 BlockDriverState *bs = (BlockDriverState *) state->bs;
7637 /* Paired with bdrv_drained_begin in bdrv_change_aio_context() */
7638 bdrv_drained_end(bs);
7640 g_free(state);
7643 static void bdrv_set_aio_context_commit(void *opaque)
7645 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
7646 BlockDriverState *bs = (BlockDriverState *) state->bs;
7647 AioContext *new_context = state->new_ctx;
7648 AioContext *old_context = bdrv_get_aio_context(bs);
7651 * Take the old AioContex when detaching it from bs.
7652 * At this point, new_context lock is already acquired, and we are now
7653 * also taking old_context. This is safe as long as bdrv_detach_aio_context
7654 * does not call AIO_POLL_WHILE().
7656 if (old_context != qemu_get_aio_context()) {
7657 aio_context_acquire(old_context);
7659 bdrv_detach_aio_context(bs);
7660 if (old_context != qemu_get_aio_context()) {
7661 aio_context_release(old_context);
7663 bdrv_attach_aio_context(bs, new_context);
7666 static TransactionActionDrv set_aio_context = {
7667 .commit = bdrv_set_aio_context_commit,
7668 .clean = bdrv_set_aio_context_clean,
7672 * Changes the AioContext used for fd handlers, timers, and BHs by this
7673 * BlockDriverState and all its children and parents.
7675 * Must be called from the main AioContext.
7677 * The caller must own the AioContext lock for the old AioContext of bs, but it
7678 * must not own the AioContext lock for new_context (unless new_context is the
7679 * same as the current context of bs).
7681 * @visited will accumulate all visited BdrvChild objects. The caller is
7682 * responsible for freeing the list afterwards.
7684 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
7685 GHashTable *visited, Transaction *tran,
7686 Error **errp)
7688 BdrvChild *c;
7689 BdrvStateSetAioContext *state;
7691 GLOBAL_STATE_CODE();
7693 if (bdrv_get_aio_context(bs) == ctx) {
7694 return true;
7697 bdrv_graph_rdlock_main_loop();
7698 QLIST_FOREACH(c, &bs->parents, next_parent) {
7699 if (!bdrv_parent_change_aio_context(c, ctx, visited, tran, errp)) {
7700 bdrv_graph_rdunlock_main_loop();
7701 return false;
7705 QLIST_FOREACH(c, &bs->children, next) {
7706 if (!bdrv_child_change_aio_context(c, ctx, visited, tran, errp)) {
7707 bdrv_graph_rdunlock_main_loop();
7708 return false;
7711 bdrv_graph_rdunlock_main_loop();
7713 state = g_new(BdrvStateSetAioContext, 1);
7714 *state = (BdrvStateSetAioContext) {
7715 .new_ctx = ctx,
7716 .bs = bs,
7719 /* Paired with bdrv_drained_end in bdrv_set_aio_context_clean() */
7720 bdrv_drained_begin(bs);
7722 tran_add(tran, &set_aio_context, state);
7724 return true;
7728 * Change bs's and recursively all of its parents' and children's AioContext
7729 * to the given new context, returning an error if that isn't possible.
7731 * If ignore_child is not NULL, that child (and its subgraph) will not
7732 * be touched.
7734 * This function still requires the caller to take the bs current
7735 * AioContext lock, otherwise draining will fail since AIO_WAIT_WHILE
7736 * assumes the lock is always held if bs is in another AioContext.
7737 * For the same reason, it temporarily also holds the new AioContext, since
7738 * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too.
7739 * Therefore the new AioContext lock must not be taken by the caller.
7741 int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
7742 BdrvChild *ignore_child, Error **errp)
7744 Transaction *tran;
7745 GHashTable *visited;
7746 int ret;
7747 AioContext *old_context = bdrv_get_aio_context(bs);
7748 GLOBAL_STATE_CODE();
7751 * Recursion phase: go through all nodes of the graph.
7752 * Take care of checking that all nodes support changing AioContext
7753 * and drain them, building a linear list of callbacks to run if everything
7754 * is successful (the transaction itself).
7756 tran = tran_new();
7757 visited = g_hash_table_new(NULL, NULL);
7758 if (ignore_child) {
7759 g_hash_table_add(visited, ignore_child);
7761 ret = bdrv_change_aio_context(bs, ctx, visited, tran, errp);
7762 g_hash_table_destroy(visited);
7765 * Linear phase: go through all callbacks collected in the transaction.
7766 * Run all callbacks collected in the recursion to switch all nodes
7767 * AioContext lock (transaction commit), or undo all changes done in the
7768 * recursion (transaction abort).
7771 if (!ret) {
7772 /* Just run clean() callbacks. No AioContext changed. */
7773 tran_abort(tran);
7774 return -EPERM;
7778 * Release old AioContext, it won't be needed anymore, as all
7779 * bdrv_drained_begin() have been called already.
7781 if (qemu_get_aio_context() != old_context) {
7782 aio_context_release(old_context);
7786 * Acquire new AioContext since bdrv_drained_end() is going to be called
7787 * after we switched all nodes in the new AioContext, and the function
7788 * assumes that the lock of the bs is always taken.
7790 if (qemu_get_aio_context() != ctx) {
7791 aio_context_acquire(ctx);
7794 tran_commit(tran);
7796 if (qemu_get_aio_context() != ctx) {
7797 aio_context_release(ctx);
7800 /* Re-acquire the old AioContext, since the caller takes and releases it. */
7801 if (qemu_get_aio_context() != old_context) {
7802 aio_context_acquire(old_context);
7805 return 0;
7808 void bdrv_add_aio_context_notifier(BlockDriverState *bs,
7809 void (*attached_aio_context)(AioContext *new_context, void *opaque),
7810 void (*detach_aio_context)(void *opaque), void *opaque)
7812 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1);
7813 *ban = (BdrvAioNotifier){
7814 .attached_aio_context = attached_aio_context,
7815 .detach_aio_context = detach_aio_context,
7816 .opaque = opaque
7818 GLOBAL_STATE_CODE();
7820 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list);
7823 void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
7824 void (*attached_aio_context)(AioContext *,
7825 void *),
7826 void (*detach_aio_context)(void *),
7827 void *opaque)
7829 BdrvAioNotifier *ban, *ban_next;
7830 GLOBAL_STATE_CODE();
7832 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
7833 if (ban->attached_aio_context == attached_aio_context &&
7834 ban->detach_aio_context == detach_aio_context &&
7835 ban->opaque == opaque &&
7836 ban->deleted == false)
7838 if (bs->walking_aio_notifiers) {
7839 ban->deleted = true;
7840 } else {
7841 bdrv_do_remove_aio_context_notifier(ban);
7843 return;
7847 abort();
7850 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
7851 BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
7852 bool force,
7853 Error **errp)
7855 GLOBAL_STATE_CODE();
7856 if (!bs->drv) {
7857 error_setg(errp, "Node is ejected");
7858 return -ENOMEDIUM;
7860 if (!bs->drv->bdrv_amend_options) {
7861 error_setg(errp, "Block driver '%s' does not support option amendment",
7862 bs->drv->format_name);
7863 return -ENOTSUP;
7865 return bs->drv->bdrv_amend_options(bs, opts, status_cb,
7866 cb_opaque, force, errp);
7870 * This function checks whether the given @to_replace is allowed to be
7871 * replaced by a node that always shows the same data as @bs. This is
7872 * used for example to verify whether the mirror job can replace
7873 * @to_replace by the target mirrored from @bs.
7874 * To be replaceable, @bs and @to_replace may either be guaranteed to
7875 * always show the same data (because they are only connected through
7876 * filters), or some driver may allow replacing one of its children
7877 * because it can guarantee that this child's data is not visible at
7878 * all (for example, for dissenting quorum children that have no other
7879 * parents).
7881 bool bdrv_recurse_can_replace(BlockDriverState *bs,
7882 BlockDriverState *to_replace)
7884 BlockDriverState *filtered;
7886 GLOBAL_STATE_CODE();
7888 if (!bs || !bs->drv) {
7889 return false;
7892 if (bs == to_replace) {
7893 return true;
7896 /* See what the driver can do */
7897 if (bs->drv->bdrv_recurse_can_replace) {
7898 return bs->drv->bdrv_recurse_can_replace(bs, to_replace);
7901 /* For filters without an own implementation, we can recurse on our own */
7902 filtered = bdrv_filter_bs(bs);
7903 if (filtered) {
7904 return bdrv_recurse_can_replace(filtered, to_replace);
7907 /* Safe default */
7908 return false;
7912 * Check whether the given @node_name can be replaced by a node that
7913 * has the same data as @parent_bs. If so, return @node_name's BDS;
7914 * NULL otherwise.
7916 * @node_name must be a (recursive) *child of @parent_bs (or this
7917 * function will return NULL).
7919 * The result (whether the node can be replaced or not) is only valid
7920 * for as long as no graph or permission changes occur.
7922 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
7923 const char *node_name, Error **errp)
7925 BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
7926 AioContext *aio_context;
7928 GLOBAL_STATE_CODE();
7930 if (!to_replace_bs) {
7931 error_setg(errp, "Failed to find node with node-name='%s'", node_name);
7932 return NULL;
7935 aio_context = bdrv_get_aio_context(to_replace_bs);
7936 aio_context_acquire(aio_context);
7938 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
7939 to_replace_bs = NULL;
7940 goto out;
7943 /* We don't want arbitrary node of the BDS chain to be replaced only the top
7944 * most non filter in order to prevent data corruption.
7945 * Another benefit is that this tests exclude backing files which are
7946 * blocked by the backing blockers.
7948 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) {
7949 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', "
7950 "because it cannot be guaranteed that doing so would not "
7951 "lead to an abrupt change of visible data",
7952 node_name, parent_bs->node_name);
7953 to_replace_bs = NULL;
7954 goto out;
7957 out:
7958 aio_context_release(aio_context);
7959 return to_replace_bs;
7963 * Iterates through the list of runtime option keys that are said to
7964 * be "strong" for a BDS. An option is called "strong" if it changes
7965 * a BDS's data. For example, the null block driver's "size" and
7966 * "read-zeroes" options are strong, but its "latency-ns" option is
7967 * not.
7969 * If a key returned by this function ends with a dot, all options
7970 * starting with that prefix are strong.
7972 static const char *const *strong_options(BlockDriverState *bs,
7973 const char *const *curopt)
7975 static const char *const global_options[] = {
7976 "driver", "filename", NULL
7979 if (!curopt) {
7980 return &global_options[0];
7983 curopt++;
7984 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
7985 curopt = bs->drv->strong_runtime_opts;
7988 return (curopt && *curopt) ? curopt : NULL;
7992 * Copies all strong runtime options from bs->options to the given
7993 * QDict. The set of strong option keys is determined by invoking
7994 * strong_options().
7996 * Returns true iff any strong option was present in bs->options (and
7997 * thus copied to the target QDict) with the exception of "filename"
7998 * and "driver". The caller is expected to use this value to decide
7999 * whether the existence of strong options prevents the generation of
8000 * a plain filename.
8002 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
8004 bool found_any = false;
8005 const char *const *option_name = NULL;
8007 if (!bs->drv) {
8008 return false;
8011 while ((option_name = strong_options(bs, option_name))) {
8012 bool option_given = false;
8014 assert(strlen(*option_name) > 0);
8015 if ((*option_name)[strlen(*option_name) - 1] != '.') {
8016 QObject *entry = qdict_get(bs->options, *option_name);
8017 if (!entry) {
8018 continue;
8021 qdict_put_obj(d, *option_name, qobject_ref(entry));
8022 option_given = true;
8023 } else {
8024 const QDictEntry *entry;
8025 for (entry = qdict_first(bs->options); entry;
8026 entry = qdict_next(bs->options, entry))
8028 if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
8029 qdict_put_obj(d, qdict_entry_key(entry),
8030 qobject_ref(qdict_entry_value(entry)));
8031 option_given = true;
8036 /* While "driver" and "filename" need to be included in a JSON filename,
8037 * their existence does not prohibit generation of a plain filename. */
8038 if (!found_any && option_given &&
8039 strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
8041 found_any = true;
8045 if (!qdict_haskey(d, "driver")) {
8046 /* Drivers created with bdrv_new_open_driver() may not have a
8047 * @driver option. Add it here. */
8048 qdict_put_str(d, "driver", bs->drv->format_name);
8051 return found_any;
8054 /* Note: This function may return false positives; it may return true
8055 * even if opening the backing file specified by bs's image header
8056 * would result in exactly bs->backing. */
8057 static bool bdrv_backing_overridden(BlockDriverState *bs)
8059 GLOBAL_STATE_CODE();
8060 if (bs->backing) {
8061 return strcmp(bs->auto_backing_file,
8062 bs->backing->bs->filename);
8063 } else {
8064 /* No backing BDS, so if the image header reports any backing
8065 * file, it must have been suppressed */
8066 return bs->auto_backing_file[0] != '\0';
8070 /* Updates the following BDS fields:
8071 * - exact_filename: A filename which may be used for opening a block device
8072 * which (mostly) equals the given BDS (even without any
8073 * other options; so reading and writing must return the same
8074 * results, but caching etc. may be different)
8075 * - full_open_options: Options which, when given when opening a block device
8076 * (without a filename), result in a BDS (mostly)
8077 * equalling the given one
8078 * - filename: If exact_filename is set, it is copied here. Otherwise,
8079 * full_open_options is converted to a JSON object, prefixed with
8080 * "json:" (for use through the JSON pseudo protocol) and put here.
8082 void bdrv_refresh_filename(BlockDriverState *bs)
8084 BlockDriver *drv = bs->drv;
8085 BdrvChild *child;
8086 BlockDriverState *primary_child_bs;
8087 QDict *opts;
8088 bool backing_overridden;
8089 bool generate_json_filename; /* Whether our default implementation should
8090 fill exact_filename (false) or not (true) */
8092 GLOBAL_STATE_CODE();
8094 if (!drv) {
8095 return;
8098 /* This BDS's file name may depend on any of its children's file names, so
8099 * refresh those first */
8100 QLIST_FOREACH(child, &bs->children, next) {
8101 bdrv_refresh_filename(child->bs);
8104 if (bs->implicit) {
8105 /* For implicit nodes, just copy everything from the single child */
8106 child = QLIST_FIRST(&bs->children);
8107 assert(QLIST_NEXT(child, next) == NULL);
8109 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
8110 child->bs->exact_filename);
8111 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
8113 qobject_unref(bs->full_open_options);
8114 bs->full_open_options = qobject_ref(child->bs->full_open_options);
8116 return;
8119 backing_overridden = bdrv_backing_overridden(bs);
8121 if (bs->open_flags & BDRV_O_NO_IO) {
8122 /* Without I/O, the backing file does not change anything.
8123 * Therefore, in such a case (primarily qemu-img), we can
8124 * pretend the backing file has not been overridden even if
8125 * it technically has been. */
8126 backing_overridden = false;
8129 /* Gather the options QDict */
8130 opts = qdict_new();
8131 generate_json_filename = append_strong_runtime_options(opts, bs);
8132 generate_json_filename |= backing_overridden;
8134 if (drv->bdrv_gather_child_options) {
8135 /* Some block drivers may not want to present all of their children's
8136 * options, or name them differently from BdrvChild.name */
8137 drv->bdrv_gather_child_options(bs, opts, backing_overridden);
8138 } else {
8139 QLIST_FOREACH(child, &bs->children, next) {
8140 if (child == bs->backing && !backing_overridden) {
8141 /* We can skip the backing BDS if it has not been overridden */
8142 continue;
8145 qdict_put(opts, child->name,
8146 qobject_ref(child->bs->full_open_options));
8149 if (backing_overridden && !bs->backing) {
8150 /* Force no backing file */
8151 qdict_put_null(opts, "backing");
8155 qobject_unref(bs->full_open_options);
8156 bs->full_open_options = opts;
8158 primary_child_bs = bdrv_primary_bs(bs);
8160 if (drv->bdrv_refresh_filename) {
8161 /* Obsolete information is of no use here, so drop the old file name
8162 * information before refreshing it */
8163 bs->exact_filename[0] = '\0';
8165 drv->bdrv_refresh_filename(bs);
8166 } else if (primary_child_bs) {
8168 * Try to reconstruct valid information from the underlying
8169 * file -- this only works for format nodes (filter nodes
8170 * cannot be probed and as such must be selected by the user
8171 * either through an options dict, or through a special
8172 * filename which the filter driver must construct in its
8173 * .bdrv_refresh_filename() implementation).
8176 bs->exact_filename[0] = '\0';
8179 * We can use the underlying file's filename if:
8180 * - it has a filename,
8181 * - the current BDS is not a filter,
8182 * - the file is a protocol BDS, and
8183 * - opening that file (as this BDS's format) will automatically create
8184 * the BDS tree we have right now, that is:
8185 * - the user did not significantly change this BDS's behavior with
8186 * some explicit (strong) options
8187 * - no non-file child of this BDS has been overridden by the user
8188 * Both of these conditions are represented by generate_json_filename.
8190 if (primary_child_bs->exact_filename[0] &&
8191 primary_child_bs->drv->bdrv_file_open &&
8192 !drv->is_filter && !generate_json_filename)
8194 strcpy(bs->exact_filename, primary_child_bs->exact_filename);
8198 if (bs->exact_filename[0]) {
8199 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
8200 } else {
8201 GString *json = qobject_to_json(QOBJECT(bs->full_open_options));
8202 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s",
8203 json->str) >= sizeof(bs->filename)) {
8204 /* Give user a hint if we truncated things. */
8205 strcpy(bs->filename + sizeof(bs->filename) - 4, "...");
8207 g_string_free(json, true);
8211 char *bdrv_dirname(BlockDriverState *bs, Error **errp)
8213 BlockDriver *drv = bs->drv;
8214 BlockDriverState *child_bs;
8216 GLOBAL_STATE_CODE();
8218 if (!drv) {
8219 error_setg(errp, "Node '%s' is ejected", bs->node_name);
8220 return NULL;
8223 if (drv->bdrv_dirname) {
8224 return drv->bdrv_dirname(bs, errp);
8227 child_bs = bdrv_primary_bs(bs);
8228 if (child_bs) {
8229 return bdrv_dirname(child_bs, errp);
8232 bdrv_refresh_filename(bs);
8233 if (bs->exact_filename[0] != '\0') {
8234 return path_combine(bs->exact_filename, "");
8237 error_setg(errp, "Cannot generate a base directory for %s nodes",
8238 drv->format_name);
8239 return NULL;
8243 * Hot add/remove a BDS's child. So the user can take a child offline when
8244 * it is broken and take a new child online
8246 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
8247 Error **errp)
8249 GLOBAL_STATE_CODE();
8250 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
8251 error_setg(errp, "The node %s does not support adding a child",
8252 bdrv_get_device_or_node_name(parent_bs));
8253 return;
8257 * Non-zoned block drivers do not follow zoned storage constraints
8258 * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
8259 * drivers in a graph.
8261 if (!parent_bs->drv->supports_zoned_children &&
8262 child_bs->bl.zoned == BLK_Z_HM) {
8264 * The host-aware model allows zoned storage constraints and random
8265 * write. Allow mixing host-aware and non-zoned drivers. Using
8266 * host-aware device as a regular device.
8268 error_setg(errp, "Cannot add a %s child to a %s parent",
8269 child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned",
8270 parent_bs->drv->supports_zoned_children ?
8271 "support zoned children" : "not support zoned children");
8272 return;
8275 if (!QLIST_EMPTY(&child_bs->parents)) {
8276 error_setg(errp, "The node %s already has a parent",
8277 child_bs->node_name);
8278 return;
8281 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
8284 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
8286 BdrvChild *tmp;
8288 GLOBAL_STATE_CODE();
8289 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
8290 error_setg(errp, "The node %s does not support removing a child",
8291 bdrv_get_device_or_node_name(parent_bs));
8292 return;
8295 QLIST_FOREACH(tmp, &parent_bs->children, next) {
8296 if (tmp == child) {
8297 break;
8301 if (!tmp) {
8302 error_setg(errp, "The node %s does not have a child named %s",
8303 bdrv_get_device_or_node_name(parent_bs),
8304 bdrv_get_device_or_node_name(child->bs));
8305 return;
8308 parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
8311 int bdrv_make_empty(BdrvChild *c, Error **errp)
8313 BlockDriver *drv = c->bs->drv;
8314 int ret;
8316 GLOBAL_STATE_CODE();
8317 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED));
8319 if (!drv->bdrv_make_empty) {
8320 error_setg(errp, "%s does not support emptying nodes",
8321 drv->format_name);
8322 return -ENOTSUP;
8325 ret = drv->bdrv_make_empty(c->bs);
8326 if (ret < 0) {
8327 error_setg_errno(errp, -ret, "Failed to empty %s",
8328 c->bs->filename);
8329 return ret;
8332 return 0;
8336 * Return the child that @bs acts as an overlay for, and from which data may be
8337 * copied in COW or COR operations. Usually this is the backing file.
8339 BdrvChild *bdrv_cow_child(BlockDriverState *bs)
8341 IO_CODE();
8343 if (!bs || !bs->drv) {
8344 return NULL;
8347 if (bs->drv->is_filter) {
8348 return NULL;
8351 if (!bs->backing) {
8352 return NULL;
8355 assert(bs->backing->role & BDRV_CHILD_COW);
8356 return bs->backing;
8360 * If @bs acts as a filter for exactly one of its children, return
8361 * that child.
8363 BdrvChild *bdrv_filter_child(BlockDriverState *bs)
8365 BdrvChild *c;
8366 IO_CODE();
8368 if (!bs || !bs->drv) {
8369 return NULL;
8372 if (!bs->drv->is_filter) {
8373 return NULL;
8376 /* Only one of @backing or @file may be used */
8377 assert(!(bs->backing && bs->file));
8379 c = bs->backing ?: bs->file;
8380 if (!c) {
8381 return NULL;
8384 assert(c->role & BDRV_CHILD_FILTERED);
8385 return c;
8389 * Return either the result of bdrv_cow_child() or bdrv_filter_child(),
8390 * whichever is non-NULL.
8392 * Return NULL if both are NULL.
8394 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs)
8396 BdrvChild *cow_child = bdrv_cow_child(bs);
8397 BdrvChild *filter_child = bdrv_filter_child(bs);
8398 IO_CODE();
8400 /* Filter nodes cannot have COW backing files */
8401 assert(!(cow_child && filter_child));
8403 return cow_child ?: filter_child;
8407 * Return the primary child of this node: For filters, that is the
8408 * filtered child. For other nodes, that is usually the child storing
8409 * metadata.
8410 * (A generally more helpful description is that this is (usually) the
8411 * child that has the same filename as @bs.)
8413 * Drivers do not necessarily have a primary child; for example quorum
8414 * does not.
8416 BdrvChild *bdrv_primary_child(BlockDriverState *bs)
8418 BdrvChild *c, *found = NULL;
8419 IO_CODE();
8421 QLIST_FOREACH(c, &bs->children, next) {
8422 if (c->role & BDRV_CHILD_PRIMARY) {
8423 assert(!found);
8424 found = c;
8428 return found;
8431 static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs,
8432 bool stop_on_explicit_filter)
8434 BdrvChild *c;
8436 if (!bs) {
8437 return NULL;
8440 while (!(stop_on_explicit_filter && !bs->implicit)) {
8441 c = bdrv_filter_child(bs);
8442 if (!c) {
8444 * A filter that is embedded in a working block graph must
8445 * have a child. Assert this here so this function does
8446 * not return a filter node that is not expected by the
8447 * caller.
8449 assert(!bs->drv || !bs->drv->is_filter);
8450 break;
8452 bs = c->bs;
8455 * Note that this treats nodes with bs->drv == NULL as not being
8456 * filters (bs->drv == NULL should be replaced by something else
8457 * anyway).
8458 * The advantage of this behavior is that this function will thus
8459 * always return a non-NULL value (given a non-NULL @bs).
8462 return bs;
8466 * Return the first BDS that has not been added implicitly or that
8467 * does not have a filtered child down the chain starting from @bs
8468 * (including @bs itself).
8470 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
8472 GLOBAL_STATE_CODE();
8473 return bdrv_do_skip_filters(bs, true);
8477 * Return the first BDS that does not have a filtered child down the
8478 * chain starting from @bs (including @bs itself).
8480 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
8482 IO_CODE();
8483 return bdrv_do_skip_filters(bs, false);
8487 * For a backing chain, return the first non-filter backing image of
8488 * the first non-filter image.
8490 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
8492 IO_CODE();
8493 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));
8497 * Check whether [offset, offset + bytes) overlaps with the cached
8498 * block-status data region.
8500 * If so, and @pnum is not NULL, set *pnum to `bsc.data_end - offset`,
8501 * which is what bdrv_bsc_is_data()'s interface needs.
8502 * Otherwise, *pnum is not touched.
8504 static bool bdrv_bsc_range_overlaps_locked(BlockDriverState *bs,
8505 int64_t offset, int64_t bytes,
8506 int64_t *pnum)
8508 BdrvBlockStatusCache *bsc = qatomic_rcu_read(&bs->block_status_cache);
8509 bool overlaps;
8511 overlaps =
8512 qatomic_read(&bsc->valid) &&
8513 ranges_overlap(offset, bytes, bsc->data_start,
8514 bsc->data_end - bsc->data_start);
8516 if (overlaps && pnum) {
8517 *pnum = bsc->data_end - offset;
8520 return overlaps;
8524 * See block_int.h for this function's documentation.
8526 bool bdrv_bsc_is_data(BlockDriverState *bs, int64_t offset, int64_t *pnum)
8528 IO_CODE();
8529 RCU_READ_LOCK_GUARD();
8530 return bdrv_bsc_range_overlaps_locked(bs, offset, 1, pnum);
8534 * See block_int.h for this function's documentation.
8536 void bdrv_bsc_invalidate_range(BlockDriverState *bs,
8537 int64_t offset, int64_t bytes)
8539 IO_CODE();
8540 RCU_READ_LOCK_GUARD();
8542 if (bdrv_bsc_range_overlaps_locked(bs, offset, bytes, NULL)) {
8543 qatomic_set(&bs->block_status_cache->valid, false);
8548 * See block_int.h for this function's documentation.
8550 void bdrv_bsc_fill(BlockDriverState *bs, int64_t offset, int64_t bytes)
8552 BdrvBlockStatusCache *new_bsc = g_new(BdrvBlockStatusCache, 1);
8553 BdrvBlockStatusCache *old_bsc;
8554 IO_CODE();
8556 *new_bsc = (BdrvBlockStatusCache) {
8557 .valid = true,
8558 .data_start = offset,
8559 .data_end = offset + bytes,
8562 QEMU_LOCK_GUARD(&bs->bsc_modify_lock);
8564 old_bsc = qatomic_rcu_read(&bs->block_status_cache);
8565 qatomic_rcu_set(&bs->block_status_cache, new_bsc);
8566 if (old_bsc) {
8567 g_free_rcu(old_bsc, rcu);