2 * QEMU System Emulator block driver
4 * Copyright (c) 2003 Fabrice Bellard
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25 #include "qemu/osdep.h"
26 #include "block/trace.h"
27 #include "block/block_int.h"
28 #include "block/blockjob.h"
29 #include "block/nbd.h"
30 #include "block/qdict.h"
31 #include "qemu/error-report.h"
32 #include "block/module_block.h"
33 #include "qemu/main-loop.h"
34 #include "qemu/module.h"
35 #include "qapi/error.h"
36 #include "qapi/qmp/qdict.h"
37 #include "qapi/qmp/qjson.h"
38 #include "qapi/qmp/qnull.h"
39 #include "qapi/qmp/qstring.h"
40 #include "qapi/qobject-output-visitor.h"
41 #include "qapi/qapi-visit-block-core.h"
42 #include "sysemu/block-backend.h"
43 #include "sysemu/sysemu.h"
44 #include "qemu/notify.h"
45 #include "qemu/option.h"
46 #include "qemu/coroutine.h"
47 #include "block/qapi.h"
48 #include "qemu/timer.h"
49 #include "qemu/cutils.h"
53 #include <sys/ioctl.h>
54 #include <sys/queue.h>
64 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
66 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
67 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
69 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
70 QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
72 static QLIST_HEAD(, BlockDriver) bdrv_drivers =
73 QLIST_HEAD_INITIALIZER(bdrv_drivers);
75 static BlockDriverState *bdrv_open_inherit(const char *filename,
76 const char *reference,
77 QDict *options, int flags,
78 BlockDriverState *parent,
79 const BdrvChildClass *child_class,
80 BdrvChildRole child_role,
83 /* If non-zero, use only whitelisted block drivers */
84 static int use_bdrv_whitelist;
87 static int is_windows_drive_prefix(const char *filename)
89 return (((filename[0] >= 'a' && filename[0] <= 'z') ||
90 (filename[0] >= 'A' && filename[0] <= 'Z')) &&
94 int is_windows_drive(const char *filename)
96 if (is_windows_drive_prefix(filename) &&
99 if (strstart(filename, "\\\\.\\", NULL) ||
100 strstart(filename, "//./", NULL))
106 size_t bdrv_opt_mem_align(BlockDriverState *bs)
108 if (!bs || !bs->drv) {
109 /* page size or 4k (hdd sector size) should be on the safe side */
110 return MAX(4096, qemu_real_host_page_size);
113 return bs->bl.opt_mem_alignment;
116 size_t bdrv_min_mem_align(BlockDriverState *bs)
118 if (!bs || !bs->drv) {
119 /* page size or 4k (hdd sector size) should be on the safe side */
120 return MAX(4096, qemu_real_host_page_size);
123 return bs->bl.min_mem_alignment;
126 /* check if the path starts with "<protocol>:" */
127 int path_has_protocol(const char *path)
132 if (is_windows_drive(path) ||
133 is_windows_drive_prefix(path)) {
136 p = path + strcspn(path, ":/\\");
138 p = path + strcspn(path, ":/");
144 int path_is_absolute(const char *path)
147 /* specific case for names like: "\\.\d:" */
148 if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
151 return (*path == '/' || *path == '\\');
153 return (*path == '/');
157 /* if filename is absolute, just return its duplicate. Otherwise, build a
158 path to it by considering it is relative to base_path. URL are
160 char *path_combine(const char *base_path, const char *filename)
162 const char *protocol_stripped = NULL;
167 if (path_is_absolute(filename)) {
168 return g_strdup(filename);
171 if (path_has_protocol(base_path)) {
172 protocol_stripped = strchr(base_path, ':');
173 if (protocol_stripped) {
177 p = protocol_stripped ?: base_path;
179 p1 = strrchr(base_path, '/');
183 p2 = strrchr(base_path, '\\');
184 if (!p1 || p2 > p1) {
199 result = g_malloc(len + strlen(filename) + 1);
200 memcpy(result, base_path, len);
201 strcpy(result + len, filename);
207 * Helper function for bdrv_parse_filename() implementations to remove optional
208 * protocol prefixes (especially "file:") from a filename and for putting the
209 * stripped filename into the options QDict if there is such a prefix.
211 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
214 if (strstart(filename, prefix, &filename)) {
215 /* Stripping the explicit protocol prefix may result in a protocol
216 * prefix being (wrongly) detected (if the filename contains a colon) */
217 if (path_has_protocol(filename)) {
218 QString *fat_filename;
220 /* This means there is some colon before the first slash; therefore,
221 * this cannot be an absolute path */
222 assert(!path_is_absolute(filename));
224 /* And we can thus fix the protocol detection issue by prefixing it
226 fat_filename = qstring_from_str("./");
227 qstring_append(fat_filename, filename);
229 assert(!path_has_protocol(qstring_get_str(fat_filename)));
231 qdict_put(options, "filename", fat_filename);
233 /* If no protocol prefix was detected, we can use the shortened
235 qdict_put_str(options, "filename", filename);
241 /* Returns whether the image file is opened as read-only. Note that this can
242 * return false and writing to the image file is still not possible because the
243 * image is inactivated. */
244 bool bdrv_is_read_only(BlockDriverState *bs)
246 return bs->read_only;
249 int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
250 bool ignore_allow_rdw, Error **errp)
252 /* Do not set read_only if copy_on_read is enabled */
253 if (bs->copy_on_read && read_only) {
254 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
255 bdrv_get_device_or_node_name(bs));
259 /* Do not clear read_only if it is prohibited */
260 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
263 error_setg(errp, "Node '%s' is read only",
264 bdrv_get_device_or_node_name(bs));
272 * Called by a driver that can only provide a read-only image.
274 * Returns 0 if the node is already read-only or it could switch the node to
275 * read-only because BDRV_O_AUTO_RDONLY is set.
277 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
278 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
279 * is not NULL, it is used as the error message for the Error object.
281 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
286 if (!(bs->open_flags & BDRV_O_RDWR)) {
289 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
293 ret = bdrv_can_set_read_only(bs, true, false, NULL);
298 bs->read_only = true;
299 bs->open_flags &= ~BDRV_O_RDWR;
304 error_setg(errp, "%s", errmsg ?: "Image is read-only");
309 * If @backing is empty, this function returns NULL without setting
310 * @errp. In all other cases, NULL will only be returned with @errp
313 * Therefore, a return value of NULL without @errp set means that
314 * there is no backing file; if @errp is set, there is one but its
315 * absolute filename cannot be generated.
317 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
321 if (backing[0] == '\0') {
323 } else if (path_has_protocol(backing) || path_is_absolute(backing)) {
324 return g_strdup(backing);
325 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
326 error_setg(errp, "Cannot use relative backing file names for '%s'",
330 return path_combine(backed, backing);
335 * If @filename is empty or NULL, this function returns NULL without
336 * setting @errp. In all other cases, NULL will only be returned with
339 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
340 const char *filename, Error **errp)
342 char *dir, *full_name;
344 if (!filename || filename[0] == '\0') {
346 } else if (path_has_protocol(filename) || path_is_absolute(filename)) {
347 return g_strdup(filename);
350 dir = bdrv_dirname(relative_to, errp);
355 full_name = g_strconcat(dir, filename, NULL);
360 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
362 return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
365 void bdrv_register(BlockDriver *bdrv)
367 assert(bdrv->format_name);
368 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
371 BlockDriverState *bdrv_new(void)
373 BlockDriverState *bs;
376 bs = g_new0(BlockDriverState, 1);
377 QLIST_INIT(&bs->dirty_bitmaps);
378 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
379 QLIST_INIT(&bs->op_blockers[i]);
381 notifier_with_return_list_init(&bs->before_write_notifiers);
382 qemu_co_mutex_init(&bs->reqs_lock);
383 qemu_mutex_init(&bs->dirty_bitmap_mutex);
385 bs->aio_context = qemu_get_aio_context();
387 qemu_co_queue_init(&bs->flush_queue);
389 for (i = 0; i < bdrv_drain_all_count; i++) {
390 bdrv_drained_begin(bs);
393 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
398 static BlockDriver *bdrv_do_find_format(const char *format_name)
402 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
403 if (!strcmp(drv1->format_name, format_name)) {
411 BlockDriver *bdrv_find_format(const char *format_name)
416 drv1 = bdrv_do_find_format(format_name);
421 /* The driver isn't registered, maybe we need to load a module */
422 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
423 if (!strcmp(block_driver_modules[i].format_name, format_name)) {
424 block_module_load_one(block_driver_modules[i].library_name);
429 return bdrv_do_find_format(format_name);
432 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
434 static const char *whitelist_rw[] = {
435 CONFIG_BDRV_RW_WHITELIST
438 static const char *whitelist_ro[] = {
439 CONFIG_BDRV_RO_WHITELIST
444 if (!whitelist_rw[0] && !whitelist_ro[0]) {
445 return 1; /* no whitelist, anything goes */
448 for (p = whitelist_rw; *p; p++) {
449 if (!strcmp(format_name, *p)) {
454 for (p = whitelist_ro; *p; p++) {
455 if (!strcmp(format_name, *p)) {
463 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
465 return bdrv_format_is_whitelisted(drv->format_name, read_only);
468 bool bdrv_uses_whitelist(void)
470 return use_bdrv_whitelist;
473 typedef struct CreateCo {
481 static void coroutine_fn bdrv_create_co_entry(void *opaque)
483 Error *local_err = NULL;
486 CreateCo *cco = opaque;
489 ret = cco->drv->bdrv_co_create_opts(cco->drv,
490 cco->filename, cco->opts, &local_err);
491 error_propagate(&cco->err, local_err);
495 int bdrv_create(BlockDriver *drv, const char* filename,
496 QemuOpts *opts, Error **errp)
503 .filename = g_strdup(filename),
509 if (!drv->bdrv_co_create_opts) {
510 error_setg(errp, "Driver '%s' does not support image creation", drv->format_name);
515 if (qemu_in_coroutine()) {
516 /* Fast-path if already in coroutine context */
517 bdrv_create_co_entry(&cco);
519 co = qemu_coroutine_create(bdrv_create_co_entry, &cco);
520 qemu_coroutine_enter(co);
521 while (cco.ret == NOT_DONE) {
522 aio_poll(qemu_get_aio_context(), true);
529 error_propagate(errp, cco.err);
531 error_setg_errno(errp, -ret, "Could not create image");
536 g_free(cco.filename);
541 * Helper function for bdrv_create_file_fallback(): Resize @blk to at
542 * least the given @minimum_size.
544 * On success, return @blk's actual length.
545 * Otherwise, return -errno.
547 static int64_t create_file_fallback_truncate(BlockBackend *blk,
548 int64_t minimum_size, Error **errp)
550 Error *local_err = NULL;
554 ret = blk_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0,
556 if (ret < 0 && ret != -ENOTSUP) {
557 error_propagate(errp, local_err);
561 size = blk_getlength(blk);
563 error_free(local_err);
564 error_setg_errno(errp, -size,
565 "Failed to inquire the new image file's length");
569 if (size < minimum_size) {
570 /* Need to grow the image, but we failed to do that */
571 error_propagate(errp, local_err);
575 error_free(local_err);
582 * Helper function for bdrv_create_file_fallback(): Zero the first
583 * sector to remove any potentially pre-existing image header.
585 static int create_file_fallback_zero_first_sector(BlockBackend *blk,
586 int64_t current_size,
589 int64_t bytes_to_clear;
592 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
593 if (bytes_to_clear) {
594 ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
596 error_setg_errno(errp, -ret,
597 "Failed to clear the new image's first sector");
606 * Simple implementation of bdrv_co_create_opts for protocol drivers
607 * which only support creation via opening a file
608 * (usually existing raw storage device)
610 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
611 const char *filename,
619 PreallocMode prealloc;
620 Error *local_err = NULL;
623 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
624 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
625 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
626 PREALLOC_MODE_OFF, &local_err);
629 error_propagate(errp, local_err);
633 if (prealloc != PREALLOC_MODE_OFF) {
634 error_setg(errp, "Unsupported preallocation mode '%s'",
635 PreallocMode_str(prealloc));
639 options = qdict_new();
640 qdict_put_str(options, "driver", drv->format_name);
642 blk = blk_new_open(filename, NULL, options,
643 BDRV_O_RDWR | BDRV_O_RESIZE, errp);
645 error_prepend(errp, "Protocol driver '%s' does not support image "
646 "creation, and opening the image failed: ",
651 size = create_file_fallback_truncate(blk, size, errp);
657 ret = create_file_fallback_zero_first_sector(blk, size, errp);
668 int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
672 drv = bdrv_find_protocol(filename, true, errp);
677 return bdrv_create(drv, filename, opts, errp);
680 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
682 Error *local_err = NULL;
688 error_setg(errp, "Block node '%s' is not opened", bs->filename);
692 if (!bs->drv->bdrv_co_delete_file) {
693 error_setg(errp, "Driver '%s' does not support image deletion",
694 bs->drv->format_name);
698 ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
700 error_propagate(errp, local_err);
707 * Try to get @bs's logical and physical block size.
708 * On success, store them in @bsz struct and return 0.
709 * On failure return -errno.
710 * @bs must not be empty.
712 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
714 BlockDriver *drv = bs->drv;
715 BlockDriverState *filtered = bdrv_filter_bs(bs);
717 if (drv && drv->bdrv_probe_blocksizes) {
718 return drv->bdrv_probe_blocksizes(bs, bsz);
719 } else if (filtered) {
720 return bdrv_probe_blocksizes(filtered, bsz);
727 * Try to get @bs's geometry (cyls, heads, sectors).
728 * On success, store them in @geo struct and return 0.
729 * On failure return -errno.
730 * @bs must not be empty.
732 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
734 BlockDriver *drv = bs->drv;
735 BlockDriverState *filtered = bdrv_filter_bs(bs);
737 if (drv && drv->bdrv_probe_geometry) {
738 return drv->bdrv_probe_geometry(bs, geo);
739 } else if (filtered) {
740 return bdrv_probe_geometry(filtered, geo);
747 * Create a uniquely-named empty temporary file.
748 * Return 0 upon success, otherwise a negative errno value.
750 int get_tmp_filename(char *filename, int size)
753 char temp_dir[MAX_PATH];
754 /* GetTempFileName requires that its output buffer (4th param)
755 have length MAX_PATH or greater. */
756 assert(size >= MAX_PATH);
757 return (GetTempPath(MAX_PATH, temp_dir)
758 && GetTempFileName(temp_dir, "qem", 0, filename)
759 ? 0 : -GetLastError());
763 tmpdir = getenv("TMPDIR");
767 if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) {
770 fd = mkstemp(filename);
774 if (close(fd) != 0) {
783 * Detect host devices. By convention, /dev/cdrom[N] is always
784 * recognized as a host CDROM.
786 static BlockDriver *find_hdev_driver(const char *filename)
788 int score_max = 0, score;
789 BlockDriver *drv = NULL, *d;
791 QLIST_FOREACH(d, &bdrv_drivers, list) {
792 if (d->bdrv_probe_device) {
793 score = d->bdrv_probe_device(filename);
794 if (score > score_max) {
804 static BlockDriver *bdrv_do_find_protocol(const char *protocol)
808 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
809 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
817 BlockDriver *bdrv_find_protocol(const char *filename,
818 bool allow_protocol_prefix,
827 /* TODO Drivers without bdrv_file_open must be specified explicitly */
830 * XXX(hch): we really should not let host device detection
831 * override an explicit protocol specification, but moving this
832 * later breaks access to device names with colons in them.
833 * Thanks to the brain-dead persistent naming schemes on udev-
834 * based Linux systems those actually are quite common.
836 drv1 = find_hdev_driver(filename);
841 if (!path_has_protocol(filename) || !allow_protocol_prefix) {
845 p = strchr(filename, ':');
848 if (len > sizeof(protocol) - 1)
849 len = sizeof(protocol) - 1;
850 memcpy(protocol, filename, len);
851 protocol[len] = '\0';
853 drv1 = bdrv_do_find_protocol(protocol);
858 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
859 if (block_driver_modules[i].protocol_name &&
860 !strcmp(block_driver_modules[i].protocol_name, protocol)) {
861 block_module_load_one(block_driver_modules[i].library_name);
866 drv1 = bdrv_do_find_protocol(protocol);
868 error_setg(errp, "Unknown protocol '%s'", protocol);
874 * Guess image format by probing its contents.
875 * This is not a good idea when your image is raw (CVE-2008-2004), but
876 * we do it anyway for backward compatibility.
878 * @buf contains the image's first @buf_size bytes.
879 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
880 * but can be smaller if the image file is smaller)
881 * @filename is its filename.
883 * For all block drivers, call the bdrv_probe() method to get its
885 * Return the first block driver with the highest probing score.
887 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
888 const char *filename)
890 int score_max = 0, score;
891 BlockDriver *drv = NULL, *d;
893 QLIST_FOREACH(d, &bdrv_drivers, list) {
895 score = d->bdrv_probe(buf, buf_size, filename);
896 if (score > score_max) {
906 static int find_image_format(BlockBackend *file, const char *filename,
907 BlockDriver **pdrv, Error **errp)
910 uint8_t buf[BLOCK_PROBE_BUF_SIZE];
913 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */
914 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
919 ret = blk_pread(file, 0, buf, sizeof(buf));
921 error_setg_errno(errp, -ret, "Could not read image for determining its "
927 drv = bdrv_probe_all(buf, ret, filename);
929 error_setg(errp, "Could not determine image format: No compatible "
938 * Set the current 'total_sectors' value
939 * Return 0 on success, -errno on error.
941 int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
943 BlockDriver *drv = bs->drv;
949 /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
953 /* query actual device if possible, otherwise just trust the hint */
954 if (drv->bdrv_getlength) {
955 int64_t length = drv->bdrv_getlength(bs);
959 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
962 bs->total_sectors = hint;
967 * Combines a QDict of new block driver @options with any missing options taken
968 * from @old_options, so that leaving out an option defaults to its old value.
970 static void bdrv_join_options(BlockDriverState *bs, QDict *options,
973 if (bs->drv && bs->drv->bdrv_join_options) {
974 bs->drv->bdrv_join_options(options, old_options);
976 qdict_join(options, old_options, false);
980 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
984 Error *local_err = NULL;
985 char *value = qemu_opt_get_del(opts, "detect-zeroes");
986 BlockdevDetectZeroesOptions detect_zeroes =
987 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
988 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
991 error_propagate(errp, local_err);
992 return detect_zeroes;
995 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
996 !(open_flags & BDRV_O_UNMAP))
998 error_setg(errp, "setting detect-zeroes to unmap is not allowed "
999 "without setting discard operation to unmap");
1002 return detect_zeroes;
1006 * Set open flags for aio engine
1008 * Return 0 on success, -1 if the engine specified is invalid
1010 int bdrv_parse_aio(const char *mode, int *flags)
1012 if (!strcmp(mode, "threads")) {
1013 /* do nothing, default */
1014 } else if (!strcmp(mode, "native")) {
1015 *flags |= BDRV_O_NATIVE_AIO;
1016 #ifdef CONFIG_LINUX_IO_URING
1017 } else if (!strcmp(mode, "io_uring")) {
1018 *flags |= BDRV_O_IO_URING;
1028 * Set open flags for a given discard mode
1030 * Return 0 on success, -1 if the discard mode was invalid.
1032 int bdrv_parse_discard_flags(const char *mode, int *flags)
1034 *flags &= ~BDRV_O_UNMAP;
1036 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
1038 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
1039 *flags |= BDRV_O_UNMAP;
1048 * Set open flags for a given cache mode
1050 * Return 0 on success, -1 if the cache mode was invalid.
1052 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
1054 *flags &= ~BDRV_O_CACHE_MASK;
1056 if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
1057 *writethrough = false;
1058 *flags |= BDRV_O_NOCACHE;
1059 } else if (!strcmp(mode, "directsync")) {
1060 *writethrough = true;
1061 *flags |= BDRV_O_NOCACHE;
1062 } else if (!strcmp(mode, "writeback")) {
1063 *writethrough = false;
1064 } else if (!strcmp(mode, "unsafe")) {
1065 *writethrough = false;
1066 *flags |= BDRV_O_NO_FLUSH;
1067 } else if (!strcmp(mode, "writethrough")) {
1068 *writethrough = true;
1076 static char *bdrv_child_get_parent_desc(BdrvChild *c)
1078 BlockDriverState *parent = c->opaque;
1079 return g_strdup(bdrv_get_device_or_node_name(parent));
1082 static void bdrv_child_cb_drained_begin(BdrvChild *child)
1084 BlockDriverState *bs = child->opaque;
1085 bdrv_do_drained_begin_quiesce(bs, NULL, false);
1088 static bool bdrv_child_cb_drained_poll(BdrvChild *child)
1090 BlockDriverState *bs = child->opaque;
1091 return bdrv_drain_poll(bs, false, NULL, false);
1094 static void bdrv_child_cb_drained_end(BdrvChild *child,
1095 int *drained_end_counter)
1097 BlockDriverState *bs = child->opaque;
1098 bdrv_drained_end_no_poll(bs, drained_end_counter);
1101 static int bdrv_child_cb_inactivate(BdrvChild *child)
1103 BlockDriverState *bs = child->opaque;
1104 assert(bs->open_flags & BDRV_O_INACTIVE);
1108 static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
1109 GSList **ignore, Error **errp)
1111 BlockDriverState *bs = child->opaque;
1112 return bdrv_can_set_aio_context(bs, ctx, ignore, errp);
1115 static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx,
1118 BlockDriverState *bs = child->opaque;
1119 return bdrv_set_aio_context_ignore(bs, ctx, ignore);
1123 * Returns the options and flags that a temporary snapshot should get, based on
1124 * the originally requested flags (the originally requested image will have
1125 * flags like a backing file)
1127 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
1128 int parent_flags, QDict *parent_options)
1130 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
1132 /* For temporary files, unconditional cache=unsafe is fine */
1133 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
1134 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
1136 /* Copy the read-only and discard options from the parent */
1137 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1138 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
1140 /* aio=native doesn't work for cache.direct=off, so disable it for the
1141 * temporary snapshot */
1142 *child_flags &= ~BDRV_O_NATIVE_AIO;
1145 static void bdrv_backing_attach(BdrvChild *c)
1147 BlockDriverState *parent = c->opaque;
1148 BlockDriverState *backing_hd = c->bs;
1150 assert(!parent->backing_blocker);
1151 error_setg(&parent->backing_blocker,
1152 "node is used as backing hd of '%s'",
1153 bdrv_get_device_or_node_name(parent));
1155 bdrv_refresh_filename(backing_hd);
1157 parent->open_flags &= ~BDRV_O_NO_BACKING;
1158 pstrcpy(parent->backing_file, sizeof(parent->backing_file),
1159 backing_hd->filename);
1160 pstrcpy(parent->backing_format, sizeof(parent->backing_format),
1161 backing_hd->drv ? backing_hd->drv->format_name : "");
1163 bdrv_op_block_all(backing_hd, parent->backing_blocker);
1164 /* Otherwise we won't be able to commit or stream */
1165 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
1166 parent->backing_blocker);
1167 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
1168 parent->backing_blocker);
1170 * We do backup in 3 ways:
1172 * The target bs is new opened, and the source is top BDS
1173 * 2. blockdev backup
1174 * Both the source and the target are top BDSes.
1175 * 3. internal backup(used for block replication)
1176 * Both the source and the target are backing file
1178 * In case 1 and 2, neither the source nor the target is the backing file.
1179 * In case 3, we will block the top BDS, so there is only one block job
1180 * for the top BDS and its backing chain.
1182 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
1183 parent->backing_blocker);
1184 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
1185 parent->backing_blocker);
1188 static void bdrv_backing_detach(BdrvChild *c)
1190 BlockDriverState *parent = c->opaque;
1192 assert(parent->backing_blocker);
1193 bdrv_op_unblock_all(c->bs, parent->backing_blocker);
1194 error_free(parent->backing_blocker);
1195 parent->backing_blocker = NULL;
1198 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
1199 const char *filename, Error **errp)
1201 BlockDriverState *parent = c->opaque;
1202 bool read_only = bdrv_is_read_only(parent);
1206 ret = bdrv_reopen_set_read_only(parent, false, errp);
1212 ret = bdrv_change_backing_file(parent, filename,
1213 base->drv ? base->drv->format_name : "",
1216 error_setg_errno(errp, -ret, "Could not update backing file link");
1220 bdrv_reopen_set_read_only(parent, true, NULL);
1227 * Returns the options and flags that a generic child of a BDS should
1228 * get, based on the given options and flags for the parent BDS.
1230 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
1231 int *child_flags, QDict *child_options,
1232 int parent_flags, QDict *parent_options)
1234 int flags = parent_flags;
1237 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL.
1238 * Generally, the question to answer is: Should this child be
1239 * format-probed by default?
1243 * Pure and non-filtered data children of non-format nodes should
1244 * be probed by default (even when the node itself has BDRV_O_PROTOCOL
1245 * set). This only affects a very limited set of drivers (namely
1246 * quorum and blkverify when this comment was written).
1247 * Force-clear BDRV_O_PROTOCOL then.
1249 if (!parent_is_format &&
1250 (role & BDRV_CHILD_DATA) &&
1251 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED)))
1253 flags &= ~BDRV_O_PROTOCOL;
1257 * All children of format nodes (except for COW children) and all
1258 * metadata children in general should never be format-probed.
1259 * Force-set BDRV_O_PROTOCOL then.
1261 if ((parent_is_format && !(role & BDRV_CHILD_COW)) ||
1262 (role & BDRV_CHILD_METADATA))
1264 flags |= BDRV_O_PROTOCOL;
1268 * If the cache mode isn't explicitly set, inherit direct and no-flush from
1271 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
1272 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
1273 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
1275 if (role & BDRV_CHILD_COW) {
1276 /* backing files are opened read-only by default */
1277 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
1278 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
1280 /* Inherit the read-only option from the parent if it's not set */
1281 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1282 qdict_copy_default(child_options, parent_options,
1283 BDRV_OPT_AUTO_READ_ONLY);
1287 * bdrv_co_pdiscard() respects unmap policy for the parent, so we
1288 * can default to enable it on lower layers regardless of the
1291 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
1293 /* Clear flags that only apply to the top layer */
1294 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
1296 if (role & BDRV_CHILD_METADATA) {
1297 flags &= ~BDRV_O_NO_IO;
1299 if (role & BDRV_CHILD_COW) {
1300 flags &= ~BDRV_O_TEMPORARY;
1303 *child_flags = flags;
1306 static void bdrv_child_cb_attach(BdrvChild *child)
1308 BlockDriverState *bs = child->opaque;
1310 if (child->role & BDRV_CHILD_COW) {
1311 bdrv_backing_attach(child);
1314 bdrv_apply_subtree_drain(child, bs);
1317 static void bdrv_child_cb_detach(BdrvChild *child)
1319 BlockDriverState *bs = child->opaque;
1321 if (child->role & BDRV_CHILD_COW) {
1322 bdrv_backing_detach(child);
1325 bdrv_unapply_subtree_drain(child, bs);
1328 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
1329 const char *filename, Error **errp)
1331 if (c->role & BDRV_CHILD_COW) {
1332 return bdrv_backing_update_filename(c, base, filename, errp);
1337 const BdrvChildClass child_of_bds = {
1338 .parent_is_bds = true,
1339 .get_parent_desc = bdrv_child_get_parent_desc,
1340 .inherit_options = bdrv_inherited_options,
1341 .drained_begin = bdrv_child_cb_drained_begin,
1342 .drained_poll = bdrv_child_cb_drained_poll,
1343 .drained_end = bdrv_child_cb_drained_end,
1344 .attach = bdrv_child_cb_attach,
1345 .detach = bdrv_child_cb_detach,
1346 .inactivate = bdrv_child_cb_inactivate,
1347 .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
1348 .set_aio_ctx = bdrv_child_cb_set_aio_ctx,
1349 .update_filename = bdrv_child_cb_update_filename,
1352 static int bdrv_open_flags(BlockDriverState *bs, int flags)
1354 int open_flags = flags;
1357 * Clear flags that are internal to the block layer before opening the
1360 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
1365 static void update_flags_from_options(int *flags, QemuOpts *opts)
1367 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
1369 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
1370 *flags |= BDRV_O_NO_FLUSH;
1373 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
1374 *flags |= BDRV_O_NOCACHE;
1377 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
1378 *flags |= BDRV_O_RDWR;
1381 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
1382 *flags |= BDRV_O_AUTO_RDONLY;
1386 static void update_options_from_flags(QDict *options, int flags)
1388 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
1389 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
1391 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
1392 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
1393 flags & BDRV_O_NO_FLUSH);
1395 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
1396 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
1398 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
1399 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
1400 flags & BDRV_O_AUTO_RDONLY);
1404 static void bdrv_assign_node_name(BlockDriverState *bs,
1405 const char *node_name,
1408 char *gen_node_name = NULL;
1411 node_name = gen_node_name = id_generate(ID_BLOCK);
1412 } else if (!id_wellformed(node_name)) {
1414 * Check for empty string or invalid characters, but not if it is
1415 * generated (generated names use characters not available to the user)
1417 error_setg(errp, "Invalid node name");
1421 /* takes care of avoiding namespaces collisions */
1422 if (blk_by_name(node_name)) {
1423 error_setg(errp, "node-name=%s is conflicting with a device id",
1428 /* takes care of avoiding duplicates node names */
1429 if (bdrv_find_node(node_name)) {
1430 error_setg(errp, "Duplicate node name");
1434 /* Make sure that the node name isn't truncated */
1435 if (strlen(node_name) >= sizeof(bs->node_name)) {
1436 error_setg(errp, "Node name too long");
1440 /* copy node name into the bs and insert it into the graph list */
1441 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
1442 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
1444 g_free(gen_node_name);
1447 static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv,
1448 const char *node_name, QDict *options,
1449 int open_flags, Error **errp)
1451 Error *local_err = NULL;
1454 bdrv_assign_node_name(bs, node_name, &local_err);
1456 error_propagate(errp, local_err);
1461 bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
1462 bs->opaque = g_malloc0(drv->instance_size);
1464 if (drv->bdrv_file_open) {
1465 assert(!drv->bdrv_needs_filename || bs->filename[0]);
1466 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
1467 } else if (drv->bdrv_open) {
1468 ret = drv->bdrv_open(bs, options, open_flags, &local_err);
1475 error_propagate(errp, local_err);
1476 } else if (bs->filename[0]) {
1477 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
1479 error_setg_errno(errp, -ret, "Could not open image");
1484 ret = refresh_total_sectors(bs, bs->total_sectors);
1486 error_setg_errno(errp, -ret, "Could not refresh total sector count");
1490 bdrv_refresh_limits(bs, &local_err);
1492 error_propagate(errp, local_err);
1496 assert(bdrv_opt_mem_align(bs) != 0);
1497 assert(bdrv_min_mem_align(bs) != 0);
1498 assert(is_power_of_2(bs->bl.request_alignment));
1500 for (i = 0; i < bs->quiesce_counter; i++) {
1501 if (drv->bdrv_co_drain_begin) {
1502 drv->bdrv_co_drain_begin(bs);
1509 if (bs->file != NULL) {
1510 bdrv_unref_child(bs, bs->file);
1518 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
1519 int flags, Error **errp)
1521 BlockDriverState *bs;
1525 bs->open_flags = flags;
1526 bs->explicit_options = qdict_new();
1527 bs->options = qdict_new();
1530 update_options_from_flags(bs->options, flags);
1532 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
1534 qobject_unref(bs->explicit_options);
1535 bs->explicit_options = NULL;
1536 qobject_unref(bs->options);
1545 QemuOptsList bdrv_runtime_opts = {
1546 .name = "bdrv_common",
1547 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
1550 .name = "node-name",
1551 .type = QEMU_OPT_STRING,
1552 .help = "Node name of the block device node",
1556 .type = QEMU_OPT_STRING,
1557 .help = "Block driver to use for the node",
1560 .name = BDRV_OPT_CACHE_DIRECT,
1561 .type = QEMU_OPT_BOOL,
1562 .help = "Bypass software writeback cache on the host",
1565 .name = BDRV_OPT_CACHE_NO_FLUSH,
1566 .type = QEMU_OPT_BOOL,
1567 .help = "Ignore flush requests",
1570 .name = BDRV_OPT_READ_ONLY,
1571 .type = QEMU_OPT_BOOL,
1572 .help = "Node is opened in read-only mode",
1575 .name = BDRV_OPT_AUTO_READ_ONLY,
1576 .type = QEMU_OPT_BOOL,
1577 .help = "Node can become read-only if opening read-write fails",
1580 .name = "detect-zeroes",
1581 .type = QEMU_OPT_STRING,
1582 .help = "try to optimize zero writes (off, on, unmap)",
1585 .name = BDRV_OPT_DISCARD,
1586 .type = QEMU_OPT_STRING,
1587 .help = "discard operation (ignore/off, unmap/on)",
1590 .name = BDRV_OPT_FORCE_SHARE,
1591 .type = QEMU_OPT_BOOL,
1592 .help = "always accept other writers (default: off)",
1594 { /* end of list */ }
1598 QemuOptsList bdrv_create_opts_simple = {
1599 .name = "simple-create-opts",
1600 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head),
1603 .name = BLOCK_OPT_SIZE,
1604 .type = QEMU_OPT_SIZE,
1605 .help = "Virtual disk size"
1608 .name = BLOCK_OPT_PREALLOC,
1609 .type = QEMU_OPT_STRING,
1610 .help = "Preallocation mode (allowed values: off)"
1612 { /* end of list */ }
1617 * Common part for opening disk images and files
1619 * Removes all processed options from *options.
1621 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
1622 QDict *options, Error **errp)
1624 int ret, open_flags;
1625 const char *filename;
1626 const char *driver_name = NULL;
1627 const char *node_name = NULL;
1628 const char *discard;
1631 Error *local_err = NULL;
1633 assert(bs->file == NULL);
1634 assert(options != NULL && bs->options != options);
1636 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
1637 if (!qemu_opts_absorb_qdict(opts, options, errp)) {
1642 update_flags_from_options(&bs->open_flags, opts);
1644 driver_name = qemu_opt_get(opts, "driver");
1645 drv = bdrv_find_format(driver_name);
1646 assert(drv != NULL);
1648 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
1650 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
1652 BDRV_OPT_FORCE_SHARE
1653 "=on can only be used with read-only images");
1659 bdrv_refresh_filename(blk_bs(file));
1660 filename = blk_bs(file)->filename;
1663 * Caution: while qdict_get_try_str() is fine, getting
1664 * non-string types would require more care. When @options
1665 * come from -blockdev or blockdev_add, its members are typed
1666 * according to the QAPI schema, but when they come from
1667 * -drive, they're all QString.
1669 filename = qdict_get_try_str(options, "filename");
1672 if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
1673 error_setg(errp, "The '%s' block driver requires a file name",
1679 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
1682 bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
1684 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
1685 if (!bs->read_only && bdrv_is_whitelisted(drv, true)) {
1686 ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
1692 !bs->read_only && bdrv_is_whitelisted(drv, true)
1693 ? "Driver '%s' can only be used for read-only devices"
1694 : "Driver '%s' is not whitelisted",
1700 /* bdrv_new() and bdrv_close() make it so */
1701 assert(atomic_read(&bs->copy_on_read) == 0);
1703 if (bs->open_flags & BDRV_O_COPY_ON_READ) {
1704 if (!bs->read_only) {
1705 bdrv_enable_copy_on_read(bs);
1707 error_setg(errp, "Can't use copy-on-read on read-only device");
1713 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
1714 if (discard != NULL) {
1715 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
1716 error_setg(errp, "Invalid discard option");
1723 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
1725 error_propagate(errp, local_err);
1730 if (filename != NULL) {
1731 pstrcpy(bs->filename, sizeof(bs->filename), filename);
1733 bs->filename[0] = '\0';
1735 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
1737 /* Open the image, either directly or using a protocol */
1738 open_flags = bdrv_open_flags(bs, bs->open_flags);
1739 node_name = qemu_opt_get(opts, "node-name");
1741 assert(!drv->bdrv_file_open || file == NULL);
1742 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
1747 qemu_opts_del(opts);
1751 qemu_opts_del(opts);
1755 static QDict *parse_json_filename(const char *filename, Error **errp)
1757 QObject *options_obj;
1761 ret = strstart(filename, "json:", &filename);
1764 options_obj = qobject_from_json(filename, errp);
1766 error_prepend(errp, "Could not parse the JSON options: ");
1770 options = qobject_to(QDict, options_obj);
1772 qobject_unref(options_obj);
1773 error_setg(errp, "Invalid JSON object given");
1777 qdict_flatten(options);
1782 static void parse_json_protocol(QDict *options, const char **pfilename,
1785 QDict *json_options;
1786 Error *local_err = NULL;
1788 /* Parse json: pseudo-protocol */
1789 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
1793 json_options = parse_json_filename(*pfilename, &local_err);
1795 error_propagate(errp, local_err);
1799 /* Options given in the filename have lower priority than options
1800 * specified directly */
1801 qdict_join(options, json_options, false);
1802 qobject_unref(json_options);
1807 * Fills in default options for opening images and converts the legacy
1808 * filename/flags pair to option QDict entries.
1809 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
1810 * block driver has been specified explicitly.
1812 static int bdrv_fill_options(QDict **options, const char *filename,
1813 int *flags, Error **errp)
1815 const char *drvname;
1816 bool protocol = *flags & BDRV_O_PROTOCOL;
1817 bool parse_filename = false;
1818 BlockDriver *drv = NULL;
1819 Error *local_err = NULL;
1822 * Caution: while qdict_get_try_str() is fine, getting non-string
1823 * types would require more care. When @options come from
1824 * -blockdev or blockdev_add, its members are typed according to
1825 * the QAPI schema, but when they come from -drive, they're all
1828 drvname = qdict_get_try_str(*options, "driver");
1830 drv = bdrv_find_format(drvname);
1832 error_setg(errp, "Unknown driver '%s'", drvname);
1835 /* If the user has explicitly specified the driver, this choice should
1836 * override the BDRV_O_PROTOCOL flag */
1837 protocol = drv->bdrv_file_open;
1841 *flags |= BDRV_O_PROTOCOL;
1843 *flags &= ~BDRV_O_PROTOCOL;
1846 /* Translate cache options from flags into options */
1847 update_options_from_flags(*options, *flags);
1849 /* Fetch the file name from the options QDict if necessary */
1850 if (protocol && filename) {
1851 if (!qdict_haskey(*options, "filename")) {
1852 qdict_put_str(*options, "filename", filename);
1853 parse_filename = true;
1855 error_setg(errp, "Can't specify 'file' and 'filename' options at "
1861 /* Find the right block driver */
1862 /* See cautionary note on accessing @options above */
1863 filename = qdict_get_try_str(*options, "filename");
1865 if (!drvname && protocol) {
1867 drv = bdrv_find_protocol(filename, parse_filename, errp);
1872 drvname = drv->format_name;
1873 qdict_put_str(*options, "driver", drvname);
1875 error_setg(errp, "Must specify either driver or file");
1880 assert(drv || !protocol);
1882 /* Driver-specific filename parsing */
1883 if (drv && drv->bdrv_parse_filename && parse_filename) {
1884 drv->bdrv_parse_filename(filename, *options, &local_err);
1886 error_propagate(errp, local_err);
1890 if (!drv->bdrv_needs_filename) {
1891 qdict_del(*options, "filename");
1898 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
1899 uint64_t perm, uint64_t shared,
1900 GSList *ignore_children,
1901 bool *tighten_restrictions, Error **errp);
1902 static void bdrv_child_abort_perm_update(BdrvChild *c);
1903 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared);
1905 typedef struct BlockReopenQueueEntry {
1908 BDRVReopenState state;
1909 QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
1910 } BlockReopenQueueEntry;
1913 * Return the flags that @bs will have after the reopens in @q have
1914 * successfully completed. If @q is NULL (or @bs is not contained in @q),
1915 * return the current flags.
1917 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
1919 BlockReopenQueueEntry *entry;
1922 QTAILQ_FOREACH(entry, q, entry) {
1923 if (entry->state.bs == bs) {
1924 return entry->state.flags;
1929 return bs->open_flags;
1932 /* Returns whether the image file can be written to after the reopen queue @q
1933 * has been successfully applied, or right now if @q is NULL. */
1934 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
1935 BlockReopenQueue *q)
1937 int flags = bdrv_reopen_get_flags(q, bs);
1939 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
1943 * Return whether the BDS can be written to. This is not necessarily
1944 * the same as !bdrv_is_read_only(bs), as inactivated images may not
1945 * be written to but do not count as read-only images.
1947 bool bdrv_is_writable(BlockDriverState *bs)
1949 return bdrv_is_writable_after_reopen(bs, NULL);
1952 static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
1953 BdrvChild *c, BdrvChildRole role,
1954 BlockReopenQueue *reopen_queue,
1955 uint64_t parent_perm, uint64_t parent_shared,
1956 uint64_t *nperm, uint64_t *nshared)
1958 assert(bs->drv && bs->drv->bdrv_child_perm);
1959 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
1960 parent_perm, parent_shared,
1962 /* TODO Take force_share from reopen_queue */
1963 if (child_bs && child_bs->force_share) {
1964 *nshared = BLK_PERM_ALL;
1969 * Check whether permissions on this node can be changed in a way that
1970 * @cumulative_perms and @cumulative_shared_perms are the new cumulative
1971 * permissions of all its parents. This involves checking whether all necessary
1972 * permission changes to child nodes can be performed.
1974 * Will set *tighten_restrictions to true if and only if new permissions have to
1975 * be taken or currently shared permissions are to be unshared. Otherwise,
1976 * errors are not fatal as long as the caller accepts that the restrictions
1977 * remain tighter than they need to be. The caller still has to abort the
1979 * @tighten_restrictions cannot be used together with @q: When reopening, we may
1980 * encounter fatal errors even though no restrictions are to be tightened. For
1981 * example, changing a node from RW to RO will fail if the WRITE permission is
1984 * A call to this function must always be followed by a call to bdrv_set_perm()
1985 * or bdrv_abort_perm_update().
1987 static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q,
1988 uint64_t cumulative_perms,
1989 uint64_t cumulative_shared_perms,
1990 GSList *ignore_children,
1991 bool *tighten_restrictions, Error **errp)
1993 BlockDriver *drv = bs->drv;
1997 assert(!q || !tighten_restrictions);
1999 if (tighten_restrictions) {
2000 uint64_t current_perms, current_shared;
2001 uint64_t added_perms, removed_shared_perms;
2003 bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared);
2005 added_perms = cumulative_perms & ~current_perms;
2006 removed_shared_perms = current_shared & ~cumulative_shared_perms;
2008 *tighten_restrictions = added_perms || removed_shared_perms;
2011 /* Write permissions never work with read-only images */
2012 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2013 !bdrv_is_writable_after_reopen(bs, q))
2015 if (!bdrv_is_writable_after_reopen(bs, NULL)) {
2016 error_setg(errp, "Block node is read-only");
2018 uint64_t current_perms, current_shared;
2019 bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared);
2020 if (current_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
2021 error_setg(errp, "Cannot make block node read-only, there is "
2024 error_setg(errp, "Cannot make block node read-only and create "
2033 * Unaligned requests will automatically be aligned to bl.request_alignment
2034 * and without RESIZE we can't extend requests to write to space beyond the
2035 * end of the image, so it's required that the image size is aligned.
2037 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2038 !(cumulative_perms & BLK_PERM_RESIZE))
2040 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) {
2041 error_setg(errp, "Cannot get 'write' permission without 'resize': "
2042 "Image size is not a multiple of request "
2048 /* Check this node */
2053 if (drv->bdrv_check_perm) {
2054 return drv->bdrv_check_perm(bs, cumulative_perms,
2055 cumulative_shared_perms, errp);
2058 /* Drivers that never have children can omit .bdrv_child_perm() */
2059 if (!drv->bdrv_child_perm) {
2060 assert(QLIST_EMPTY(&bs->children));
2064 /* Check all children */
2065 QLIST_FOREACH(c, &bs->children, next) {
2066 uint64_t cur_perm, cur_shared;
2067 bool child_tighten_restr;
2069 bdrv_child_perm(bs, c->bs, c, c->role, q,
2070 cumulative_perms, cumulative_shared_perms,
2071 &cur_perm, &cur_shared);
2072 ret = bdrv_child_check_perm(c, q, cur_perm, cur_shared, ignore_children,
2073 tighten_restrictions ? &child_tighten_restr
2076 if (tighten_restrictions) {
2077 *tighten_restrictions |= child_tighten_restr;
2088 * Notifies drivers that after a previous bdrv_check_perm() call, the
2089 * permission update is not performed and any preparations made for it (e.g.
2090 * taken file locks) need to be undone.
2092 * This function recursively notifies all child nodes.
2094 static void bdrv_abort_perm_update(BlockDriverState *bs)
2096 BlockDriver *drv = bs->drv;
2103 if (drv->bdrv_abort_perm_update) {
2104 drv->bdrv_abort_perm_update(bs);
2107 QLIST_FOREACH(c, &bs->children, next) {
2108 bdrv_child_abort_perm_update(c);
2112 static void bdrv_set_perm(BlockDriverState *bs, uint64_t cumulative_perms,
2113 uint64_t cumulative_shared_perms)
2115 BlockDriver *drv = bs->drv;
2122 /* Update this node */
2123 if (drv->bdrv_set_perm) {
2124 drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
2127 /* Drivers that never have children can omit .bdrv_child_perm() */
2128 if (!drv->bdrv_child_perm) {
2129 assert(QLIST_EMPTY(&bs->children));
2133 /* Update all children */
2134 QLIST_FOREACH(c, &bs->children, next) {
2135 uint64_t cur_perm, cur_shared;
2136 bdrv_child_perm(bs, c->bs, c, c->role, NULL,
2137 cumulative_perms, cumulative_shared_perms,
2138 &cur_perm, &cur_shared);
2139 bdrv_child_set_perm(c, cur_perm, cur_shared);
2143 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
2144 uint64_t *shared_perm)
2147 uint64_t cumulative_perms = 0;
2148 uint64_t cumulative_shared_perms = BLK_PERM_ALL;
2150 QLIST_FOREACH(c, &bs->parents, next_parent) {
2151 cumulative_perms |= c->perm;
2152 cumulative_shared_perms &= c->shared_perm;
2155 *perm = cumulative_perms;
2156 *shared_perm = cumulative_shared_perms;
2159 static char *bdrv_child_user_desc(BdrvChild *c)
2161 if (c->klass->get_parent_desc) {
2162 return c->klass->get_parent_desc(c);
2165 return g_strdup("another user");
2168 char *bdrv_perm_names(uint64_t perm)
2174 { BLK_PERM_CONSISTENT_READ, "consistent read" },
2175 { BLK_PERM_WRITE, "write" },
2176 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
2177 { BLK_PERM_RESIZE, "resize" },
2178 { BLK_PERM_GRAPH_MOD, "change children" },
2182 GString *result = g_string_sized_new(30);
2183 struct perm_name *p;
2185 for (p = permissions; p->name; p++) {
2186 if (perm & p->perm) {
2187 if (result->len > 0) {
2188 g_string_append(result, ", ");
2190 g_string_append(result, p->name);
2194 return g_string_free(result, FALSE);
2198 * Checks whether a new reference to @bs can be added if the new user requires
2199 * @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is
2200 * set, the BdrvChild objects in this list are ignored in the calculations;
2201 * this allows checking permission updates for an existing reference.
2203 * See bdrv_check_perm() for the semantics of @tighten_restrictions.
2205 * Needs to be followed by a call to either bdrv_set_perm() or
2206 * bdrv_abort_perm_update(). */
2207 static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q,
2208 uint64_t new_used_perm,
2209 uint64_t new_shared_perm,
2210 GSList *ignore_children,
2211 bool *tighten_restrictions,
2215 uint64_t cumulative_perms = new_used_perm;
2216 uint64_t cumulative_shared_perms = new_shared_perm;
2218 assert(!q || !tighten_restrictions);
2220 /* There is no reason why anyone couldn't tolerate write_unchanged */
2221 assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED);
2223 QLIST_FOREACH(c, &bs->parents, next_parent) {
2224 if (g_slist_find(ignore_children, c)) {
2228 if ((new_used_perm & c->shared_perm) != new_used_perm) {
2229 char *user = bdrv_child_user_desc(c);
2230 char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm);
2232 if (tighten_restrictions) {
2233 *tighten_restrictions = true;
2236 error_setg(errp, "Conflicts with use by %s as '%s', which does not "
2238 user, c->name, perm_names, bdrv_get_node_name(c->bs));
2244 if ((c->perm & new_shared_perm) != c->perm) {
2245 char *user = bdrv_child_user_desc(c);
2246 char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm);
2248 if (tighten_restrictions) {
2249 *tighten_restrictions = true;
2252 error_setg(errp, "Conflicts with use by %s as '%s', which uses "
2254 user, c->name, perm_names, bdrv_get_node_name(c->bs));
2260 cumulative_perms |= c->perm;
2261 cumulative_shared_perms &= c->shared_perm;
2264 return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms,
2265 ignore_children, tighten_restrictions, errp);
2268 /* Needs to be followed by a call to either bdrv_child_set_perm() or
2269 * bdrv_child_abort_perm_update(). */
2270 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
2271 uint64_t perm, uint64_t shared,
2272 GSList *ignore_children,
2273 bool *tighten_restrictions, Error **errp)
2277 ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c);
2278 ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children,
2279 tighten_restrictions, errp);
2280 g_slist_free(ignore_children);
2286 if (!c->has_backup_perm) {
2287 c->has_backup_perm = true;
2288 c->backup_perm = c->perm;
2289 c->backup_shared_perm = c->shared_perm;
2292 * Note: it's OK if c->has_backup_perm was already set, as we can find the
2293 * same child twice during check_perm procedure
2297 c->shared_perm = shared;
2302 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared)
2304 uint64_t cumulative_perms, cumulative_shared_perms;
2306 c->has_backup_perm = false;
2309 c->shared_perm = shared;
2311 bdrv_get_cumulative_perm(c->bs, &cumulative_perms,
2312 &cumulative_shared_perms);
2313 bdrv_set_perm(c->bs, cumulative_perms, cumulative_shared_perms);
2316 static void bdrv_child_abort_perm_update(BdrvChild *c)
2318 if (c->has_backup_perm) {
2319 c->perm = c->backup_perm;
2320 c->shared_perm = c->backup_shared_perm;
2321 c->has_backup_perm = false;
2324 bdrv_abort_perm_update(c->bs);
2327 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
2330 Error *local_err = NULL;
2332 bool tighten_restrictions;
2334 ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL,
2335 &tighten_restrictions, &local_err);
2337 bdrv_child_abort_perm_update(c);
2338 if (tighten_restrictions) {
2339 error_propagate(errp, local_err);
2342 * Our caller may intend to only loosen restrictions and
2343 * does not expect this function to fail. Errors are not
2344 * fatal in such a case, so we can just hide them from our
2347 error_free(local_err);
2353 bdrv_child_set_perm(c, perm, shared);
2358 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
2360 uint64_t parent_perms, parent_shared;
2361 uint64_t perms, shared;
2363 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
2364 bdrv_child_perm(bs, c->bs, c, c->role, NULL,
2365 parent_perms, parent_shared, &perms, &shared);
2367 return bdrv_child_try_set_perm(c, perms, shared, errp);
2371 * Default implementation for .bdrv_child_perm() for block filters:
2372 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the
2375 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
2377 BlockReopenQueue *reopen_queue,
2378 uint64_t perm, uint64_t shared,
2379 uint64_t *nperm, uint64_t *nshared)
2381 *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
2382 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
2385 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c,
2387 BlockReopenQueue *reopen_queue,
2388 uint64_t perm, uint64_t shared,
2389 uint64_t *nperm, uint64_t *nshared)
2391 assert(role & BDRV_CHILD_COW);
2394 * We want consistent read from backing files if the parent needs it.
2395 * No other operations are performed on backing files.
2397 perm &= BLK_PERM_CONSISTENT_READ;
2400 * If the parent can deal with changing data, we're okay with a
2401 * writable and resizable backing file.
2402 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too?
2404 if (shared & BLK_PERM_WRITE) {
2405 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
2410 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD |
2411 BLK_PERM_WRITE_UNCHANGED;
2413 if (bs->open_flags & BDRV_O_INACTIVE) {
2414 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2421 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c,
2423 BlockReopenQueue *reopen_queue,
2424 uint64_t perm, uint64_t shared,
2425 uint64_t *nperm, uint64_t *nshared)
2429 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA));
2431 flags = bdrv_reopen_get_flags(reopen_queue, bs);
2434 * Apart from the modifications below, the same permissions are
2435 * forwarded and left alone as for filters
2437 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2438 perm, shared, &perm, &shared);
2440 if (role & BDRV_CHILD_METADATA) {
2441 /* Format drivers may touch metadata even if the guest doesn't write */
2442 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
2443 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2447 * bs->file always needs to be consistent because of the
2448 * metadata. We can never allow other users to resize or write
2451 if (!(flags & BDRV_O_NO_IO)) {
2452 perm |= BLK_PERM_CONSISTENT_READ;
2454 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
2457 if (role & BDRV_CHILD_DATA) {
2459 * Technically, everything in this block is a subset of the
2460 * BDRV_CHILD_METADATA path taken above, and so this could
2461 * be an "else if" branch. However, that is not obvious, and
2462 * this function is not performance critical, therefore we let
2463 * this be an independent "if".
2467 * We cannot allow other users to resize the file because the
2468 * format driver might have some assumptions about the size
2469 * (e.g. because it is stored in metadata, or because the file
2470 * is split into fixed-size data files).
2472 shared &= ~BLK_PERM_RESIZE;
2475 * WRITE_UNCHANGED often cannot be performed as such on the
2476 * data file. For example, the qcow2 driver may still need to
2477 * write copied clusters on copy-on-read.
2479 if (perm & BLK_PERM_WRITE_UNCHANGED) {
2480 perm |= BLK_PERM_WRITE;
2484 * If the data file is written to, the format driver may
2485 * expect to be able to resize it by writing beyond the EOF.
2487 if (perm & BLK_PERM_WRITE) {
2488 perm |= BLK_PERM_RESIZE;
2492 if (bs->open_flags & BDRV_O_INACTIVE) {
2493 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2500 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
2501 BdrvChildRole role, BlockReopenQueue *reopen_queue,
2502 uint64_t perm, uint64_t shared,
2503 uint64_t *nperm, uint64_t *nshared)
2505 if (role & BDRV_CHILD_FILTERED) {
2506 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
2508 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2509 perm, shared, nperm, nshared);
2510 } else if (role & BDRV_CHILD_COW) {
2511 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA)));
2512 bdrv_default_perms_for_cow(bs, c, role, reopen_queue,
2513 perm, shared, nperm, nshared);
2514 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) {
2515 bdrv_default_perms_for_storage(bs, c, role, reopen_queue,
2516 perm, shared, nperm, nshared);
2518 g_assert_not_reached();
2522 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
2524 static const uint64_t permissions[] = {
2525 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ,
2526 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE,
2527 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED,
2528 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE,
2529 [BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD,
2532 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX);
2533 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1);
2535 assert(qapi_perm < BLOCK_PERMISSION__MAX);
2537 return permissions[qapi_perm];
2540 static void bdrv_replace_child_noperm(BdrvChild *child,
2541 BlockDriverState *new_bs)
2543 BlockDriverState *old_bs = child->bs;
2544 int new_bs_quiesce_counter;
2547 assert(!child->frozen);
2549 if (old_bs && new_bs) {
2550 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
2553 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0);
2554 drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter;
2557 * If the new child node is drained but the old one was not, flush
2558 * all outstanding requests to the old child node.
2560 while (drain_saldo > 0 && child->klass->drained_begin) {
2561 bdrv_parent_drained_begin_single(child, true);
2566 /* Detach first so that the recursive drain sections coming from @child
2567 * are already gone and we only end the drain sections that came from
2569 if (child->klass->detach) {
2570 child->klass->detach(child);
2572 QLIST_REMOVE(child, next_parent);
2578 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
2581 * Detaching the old node may have led to the new node's
2582 * quiesce_counter having been decreased. Not a problem, we
2583 * just need to recognize this here and then invoke
2584 * drained_end appropriately more often.
2586 assert(new_bs->quiesce_counter <= new_bs_quiesce_counter);
2587 drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter;
2589 /* Attach only after starting new drained sections, so that recursive
2590 * drain sections coming from @child don't get an extra .drained_begin
2592 if (child->klass->attach) {
2593 child->klass->attach(child);
2598 * If the old child node was drained but the new one is not, allow
2599 * requests to come in only after the new node has been attached.
2601 while (drain_saldo < 0 && child->klass->drained_end) {
2602 bdrv_parent_drained_end_single(child);
2608 * Updates @child to change its reference to point to @new_bs, including
2609 * checking and applying the necessary permisson updates both to the old node
2612 * NULL is passed as @new_bs for removing the reference before freeing @child.
2614 * If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this
2615 * function uses bdrv_set_perm() to update the permissions according to the new
2616 * reference that @new_bs gets.
2618 * Callers must ensure that child->frozen is false.
2620 static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
2622 BlockDriverState *old_bs = child->bs;
2623 uint64_t perm, shared_perm;
2625 /* Asserts that child->frozen == false */
2626 bdrv_replace_child_noperm(child, new_bs);
2629 * Start with the new node's permissions. If @new_bs is a (direct
2630 * or indirect) child of @old_bs, we must complete the permission
2631 * update on @new_bs before we loosen the restrictions on @old_bs.
2632 * Otherwise, bdrv_check_perm() on @old_bs would re-initiate
2633 * updating the permissions of @new_bs, and thus not purely loosen
2637 bdrv_get_cumulative_perm(new_bs, &perm, &shared_perm);
2638 bdrv_set_perm(new_bs, perm, shared_perm);
2642 /* Update permissions for old node. This is guaranteed to succeed
2643 * because we're just taking a parent away, so we're loosening
2645 bool tighten_restrictions;
2648 bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm);
2649 ret = bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL,
2650 &tighten_restrictions, NULL);
2651 assert(tighten_restrictions == false);
2653 /* We only tried to loosen restrictions, so errors are not fatal */
2654 bdrv_abort_perm_update(old_bs);
2656 bdrv_set_perm(old_bs, perm, shared_perm);
2659 /* When the parent requiring a non-default AioContext is removed, the
2660 * node moves back to the main AioContext */
2661 bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL);
2666 * This function steals the reference to child_bs from the caller.
2667 * That reference is later dropped by bdrv_root_unref_child().
2669 * On failure NULL is returned, errp is set and the reference to
2670 * child_bs is also dropped.
2672 * The caller must hold the AioContext lock @child_bs, but not that of @ctx
2673 * (unless @child_bs is already in @ctx).
2675 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
2676 const char *child_name,
2677 const BdrvChildClass *child_class,
2678 BdrvChildRole child_role,
2680 uint64_t perm, uint64_t shared_perm,
2681 void *opaque, Error **errp)
2684 Error *local_err = NULL;
2687 ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, NULL,
2690 bdrv_abort_perm_update(child_bs);
2691 bdrv_unref(child_bs);
2695 child = g_new(BdrvChild, 1);
2696 *child = (BdrvChild) {
2698 .name = g_strdup(child_name),
2699 .klass = child_class,
2702 .shared_perm = shared_perm,
2706 /* If the AioContexts don't match, first try to move the subtree of
2707 * child_bs into the AioContext of the new parent. If this doesn't work,
2708 * try moving the parent into the AioContext of child_bs instead. */
2709 if (bdrv_get_aio_context(child_bs) != ctx) {
2710 ret = bdrv_try_set_aio_context(child_bs, ctx, &local_err);
2711 if (ret < 0 && child_class->can_set_aio_ctx) {
2712 GSList *ignore = g_slist_prepend(NULL, child);
2713 ctx = bdrv_get_aio_context(child_bs);
2714 if (child_class->can_set_aio_ctx(child, ctx, &ignore, NULL)) {
2715 error_free(local_err);
2717 g_slist_free(ignore);
2718 ignore = g_slist_prepend(NULL, child);
2719 child_class->set_aio_ctx(child, ctx, &ignore);
2721 g_slist_free(ignore);
2724 error_propagate(errp, local_err);
2726 bdrv_abort_perm_update(child_bs);
2727 bdrv_unref(child_bs);
2732 /* This performs the matching bdrv_set_perm() for the above check. */
2733 bdrv_replace_child(child, child_bs);
2739 * This function transfers the reference to child_bs from the caller
2740 * to parent_bs. That reference is later dropped by parent_bs on
2741 * bdrv_close() or if someone calls bdrv_unref_child().
2743 * On failure NULL is returned, errp is set and the reference to
2744 * child_bs is also dropped.
2746 * If @parent_bs and @child_bs are in different AioContexts, the caller must
2747 * hold the AioContext lock for @child_bs, but not for @parent_bs.
2749 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
2750 BlockDriverState *child_bs,
2751 const char *child_name,
2752 const BdrvChildClass *child_class,
2753 BdrvChildRole child_role,
2757 uint64_t perm, shared_perm;
2759 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
2761 assert(parent_bs->drv);
2762 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
2763 perm, shared_perm, &perm, &shared_perm);
2765 child = bdrv_root_attach_child(child_bs, child_name, child_class,
2766 child_role, bdrv_get_aio_context(parent_bs),
2767 perm, shared_perm, parent_bs, errp);
2768 if (child == NULL) {
2772 QLIST_INSERT_HEAD(&parent_bs->children, child, next);
2776 static void bdrv_detach_child(BdrvChild *child)
2778 QLIST_SAFE_REMOVE(child, next);
2780 bdrv_replace_child(child, NULL);
2782 g_free(child->name);
2786 /* Callers must ensure that child->frozen is false. */
2787 void bdrv_root_unref_child(BdrvChild *child)
2789 BlockDriverState *child_bs;
2791 child_bs = child->bs;
2792 bdrv_detach_child(child);
2793 bdrv_unref(child_bs);
2797 * Clear all inherits_from pointers from children and grandchildren of
2798 * @root that point to @root, where necessary.
2800 static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child)
2804 if (child->bs->inherits_from == root) {
2806 * Remove inherits_from only when the last reference between root and
2807 * child->bs goes away.
2809 QLIST_FOREACH(c, &root->children, next) {
2810 if (c != child && c->bs == child->bs) {
2815 child->bs->inherits_from = NULL;
2819 QLIST_FOREACH(c, &child->bs->children, next) {
2820 bdrv_unset_inherits_from(root, c);
2824 /* Callers must ensure that child->frozen is false. */
2825 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
2827 if (child == NULL) {
2831 bdrv_unset_inherits_from(parent, child);
2832 bdrv_root_unref_child(child);
2836 static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
2839 QLIST_FOREACH(c, &bs->parents, next_parent) {
2840 if (c->klass->change_media) {
2841 c->klass->change_media(c, load);
2846 /* Return true if you can reach parent going through child->inherits_from
2847 * recursively. If parent or child are NULL, return false */
2848 static bool bdrv_inherits_from_recursive(BlockDriverState *child,
2849 BlockDriverState *parent)
2851 while (child && child != parent) {
2852 child = child->inherits_from;
2855 return child != NULL;
2859 * Return the BdrvChildRole for @bs's backing child. bs->backing is
2860 * mostly used for COW backing children (role = COW), but also for
2861 * filtered children (role = FILTERED | PRIMARY).
2863 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
2865 if (bs->drv && bs->drv->is_filter) {
2866 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
2868 return BDRV_CHILD_COW;
2873 * Sets the bs->backing link of a BDS. A new reference is created; callers
2874 * which don't need their own reference any more must call bdrv_unref().
2876 void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
2879 bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
2880 bdrv_inherits_from_recursive(backing_hd, bs);
2882 if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) {
2887 bdrv_ref(backing_hd);
2891 /* Cannot be frozen, we checked that above */
2892 bdrv_unref_child(bs, bs->backing);
2900 bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds,
2901 bdrv_backing_role(bs), errp);
2902 /* If backing_hd was already part of bs's backing chain, and
2903 * inherits_from pointed recursively to bs then let's update it to
2904 * point directly to bs (else it will become NULL). */
2905 if (bs->backing && update_inherits_from) {
2906 backing_hd->inherits_from = bs;
2910 bdrv_refresh_limits(bs, NULL);
2914 * Opens the backing file for a BlockDriverState if not yet open
2916 * bdref_key specifies the key for the image's BlockdevRef in the options QDict.
2917 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
2918 * itself, all options starting with "${bdref_key}." are considered part of the
2921 * TODO Can this be unified with bdrv_open_image()?
2923 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
2924 const char *bdref_key, Error **errp)
2926 char *backing_filename = NULL;
2927 char *bdref_key_dot;
2928 const char *reference = NULL;
2930 bool implicit_backing = false;
2931 BlockDriverState *backing_hd;
2933 QDict *tmp_parent_options = NULL;
2934 Error *local_err = NULL;
2936 if (bs->backing != NULL) {
2940 /* NULL means an empty set of options */
2941 if (parent_options == NULL) {
2942 tmp_parent_options = qdict_new();
2943 parent_options = tmp_parent_options;
2946 bs->open_flags &= ~BDRV_O_NO_BACKING;
2948 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
2949 qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
2950 g_free(bdref_key_dot);
2953 * Caution: while qdict_get_try_str() is fine, getting non-string
2954 * types would require more care. When @parent_options come from
2955 * -blockdev or blockdev_add, its members are typed according to
2956 * the QAPI schema, but when they come from -drive, they're all
2959 reference = qdict_get_try_str(parent_options, bdref_key);
2960 if (reference || qdict_haskey(options, "file.filename")) {
2961 /* keep backing_filename NULL */
2962 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
2963 qobject_unref(options);
2966 if (qdict_size(options) == 0) {
2967 /* If the user specifies options that do not modify the
2968 * backing file's behavior, we might still consider it the
2969 * implicit backing file. But it's easier this way, and
2970 * just specifying some of the backing BDS's options is
2971 * only possible with -drive anyway (otherwise the QAPI
2972 * schema forces the user to specify everything). */
2973 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
2976 backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
2979 error_propagate(errp, local_err);
2980 qobject_unref(options);
2985 if (!bs->drv || !bs->drv->supports_backing) {
2987 error_setg(errp, "Driver doesn't support backing files");
2988 qobject_unref(options);
2993 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
2994 qdict_put_str(options, "driver", bs->backing_format);
2997 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
2998 &child_of_bds, bdrv_backing_role(bs), errp);
3000 bs->open_flags |= BDRV_O_NO_BACKING;
3001 error_prepend(errp, "Could not open backing file: ");
3006 if (implicit_backing) {
3007 bdrv_refresh_filename(backing_hd);
3008 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
3009 backing_hd->filename);
3012 /* Hook up the backing file link; drop our reference, bs owns the
3013 * backing_hd reference now */
3014 bdrv_set_backing_hd(bs, backing_hd, &local_err);
3015 bdrv_unref(backing_hd);
3017 error_propagate(errp, local_err);
3022 qdict_del(parent_options, bdref_key);
3025 g_free(backing_filename);
3026 qobject_unref(tmp_parent_options);
3030 static BlockDriverState *
3031 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
3032 BlockDriverState *parent, const BdrvChildClass *child_class,
3033 BdrvChildRole child_role, bool allow_none, Error **errp)
3035 BlockDriverState *bs = NULL;
3036 QDict *image_options;
3037 char *bdref_key_dot;
3038 const char *reference;
3040 assert(child_class != NULL);
3042 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3043 qdict_extract_subqdict(options, &image_options, bdref_key_dot);
3044 g_free(bdref_key_dot);
3047 * Caution: while qdict_get_try_str() is fine, getting non-string
3048 * types would require more care. When @options come from
3049 * -blockdev or blockdev_add, its members are typed according to
3050 * the QAPI schema, but when they come from -drive, they're all
3053 reference = qdict_get_try_str(options, bdref_key);
3054 if (!filename && !reference && !qdict_size(image_options)) {
3056 error_setg(errp, "A block device must be specified for \"%s\"",
3059 qobject_unref(image_options);
3063 bs = bdrv_open_inherit(filename, reference, image_options, 0,
3064 parent, child_class, child_role, errp);
3070 qdict_del(options, bdref_key);
3075 * Opens a disk image whose options are given as BlockdevRef in another block
3078 * If allow_none is true, no image will be opened if filename is false and no
3079 * BlockdevRef is given. NULL will be returned, but errp remains unset.
3081 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
3082 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3083 * itself, all options starting with "${bdref_key}." are considered part of the
3086 * The BlockdevRef will be removed from the options QDict.
3088 BdrvChild *bdrv_open_child(const char *filename,
3089 QDict *options, const char *bdref_key,
3090 BlockDriverState *parent,
3091 const BdrvChildClass *child_class,
3092 BdrvChildRole child_role,
3093 bool allow_none, Error **errp)
3095 BlockDriverState *bs;
3097 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
3098 child_role, allow_none, errp);
3103 return bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
3108 * TODO Future callers may need to specify parent/child_class in order for
3109 * option inheritance to work. Existing callers use it for the root node.
3111 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
3113 BlockDriverState *bs = NULL;
3114 QObject *obj = NULL;
3115 QDict *qdict = NULL;
3116 const char *reference = NULL;
3119 if (ref->type == QTYPE_QSTRING) {
3120 reference = ref->u.reference;
3122 BlockdevOptions *options = &ref->u.definition;
3123 assert(ref->type == QTYPE_QDICT);
3125 v = qobject_output_visitor_new(&obj);
3126 visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
3127 visit_complete(v, &obj);
3129 qdict = qobject_to(QDict, obj);
3130 qdict_flatten(qdict);
3132 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for
3133 * compatibility with other callers) rather than what we want as the
3134 * real defaults. Apply the defaults here instead. */
3135 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
3136 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
3137 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
3138 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
3142 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp);
3149 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
3151 QDict *snapshot_options,
3154 /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
3155 char *tmp_filename = g_malloc0(PATH_MAX + 1);
3157 QemuOpts *opts = NULL;
3158 BlockDriverState *bs_snapshot = NULL;
3159 Error *local_err = NULL;
3162 /* if snapshot, we create a temporary backing file and open it
3163 instead of opening 'filename' directly */
3165 /* Get the required size from the image */
3166 total_size = bdrv_getlength(bs);
3167 if (total_size < 0) {
3168 error_setg_errno(errp, -total_size, "Could not get image size");
3172 /* Create the temporary image */
3173 ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);
3175 error_setg_errno(errp, -ret, "Could not get temporary filename");
3179 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
3181 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
3182 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
3183 qemu_opts_del(opts);
3185 error_prepend(errp, "Could not create temporary overlay '%s': ",
3190 /* Prepare options QDict for the temporary file */
3191 qdict_put_str(snapshot_options, "file.driver", "file");
3192 qdict_put_str(snapshot_options, "file.filename", tmp_filename);
3193 qdict_put_str(snapshot_options, "driver", "qcow2");
3195 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
3196 snapshot_options = NULL;
3201 /* bdrv_append() consumes a strong reference to bs_snapshot
3202 * (i.e. it will call bdrv_unref() on it) even on error, so in
3203 * order to be able to return one, we have to increase
3204 * bs_snapshot's refcount here */
3205 bdrv_ref(bs_snapshot);
3206 bdrv_append(bs_snapshot, bs, &local_err);
3208 error_propagate(errp, local_err);
3214 qobject_unref(snapshot_options);
3215 g_free(tmp_filename);
3220 * Opens a disk image (raw, qcow2, vmdk, ...)
3222 * options is a QDict of options to pass to the block drivers, or NULL for an
3223 * empty set of options. The reference to the QDict belongs to the block layer
3224 * after the call (even on failure), so if the caller intends to reuse the
3225 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
3227 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
3228 * If it is not NULL, the referenced BDS will be reused.
3230 * The reference parameter may be used to specify an existing block device which
3231 * should be opened. If specified, neither options nor a filename may be given,
3232 * nor can an existing BDS be reused (that is, *pbs has to be NULL).
3234 static BlockDriverState *bdrv_open_inherit(const char *filename,
3235 const char *reference,
3236 QDict *options, int flags,
3237 BlockDriverState *parent,
3238 const BdrvChildClass *child_class,
3239 BdrvChildRole child_role,
3243 BlockBackend *file = NULL;
3244 BlockDriverState *bs;
3245 BlockDriver *drv = NULL;
3247 const char *drvname;
3248 const char *backing;
3249 Error *local_err = NULL;
3250 QDict *snapshot_options = NULL;
3251 int snapshot_flags = 0;
3253 assert(!child_class || !flags);
3254 assert(!child_class == !parent);
3257 bool options_non_empty = options ? qdict_size(options) : false;
3258 qobject_unref(options);
3260 if (filename || options_non_empty) {
3261 error_setg(errp, "Cannot reference an existing block device with "
3262 "additional options or a new filename");
3266 bs = bdrv_lookup_bs(reference, reference, errp);
3277 /* NULL means an empty set of options */
3278 if (options == NULL) {
3279 options = qdict_new();
3282 /* json: syntax counts as explicit options, as if in the QDict */
3283 parse_json_protocol(options, &filename, &local_err);
3288 bs->explicit_options = qdict_clone_shallow(options);
3291 bool parent_is_format;
3294 parent_is_format = parent->drv->is_format;
3297 * parent->drv is not set yet because this node is opened for
3298 * (potential) format probing. That means that @parent is going
3299 * to be a format node.
3301 parent_is_format = true;
3304 bs->inherits_from = parent;
3305 child_class->inherit_options(child_role, parent_is_format,
3307 parent->open_flags, parent->options);
3310 ret = bdrv_fill_options(&options, filename, &flags, &local_err);
3316 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
3317 * Caution: getting a boolean member of @options requires care.
3318 * When @options come from -blockdev or blockdev_add, members are
3319 * typed according to the QAPI schema, but when they come from
3320 * -drive, they're all QString.
3322 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
3323 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
3324 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
3326 flags &= ~BDRV_O_RDWR;
3329 if (flags & BDRV_O_SNAPSHOT) {
3330 snapshot_options = qdict_new();
3331 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options,
3333 /* Let bdrv_backing_options() override "read-only" */
3334 qdict_del(options, BDRV_OPT_READ_ONLY);
3335 bdrv_inherited_options(BDRV_CHILD_COW, true,
3336 &flags, options, flags, options);
3339 bs->open_flags = flags;
3340 bs->options = options;
3341 options = qdict_clone_shallow(options);
3343 /* Find the right image format driver */
3344 /* See cautionary note on accessing @options above */
3345 drvname = qdict_get_try_str(options, "driver");
3347 drv = bdrv_find_format(drvname);
3349 error_setg(errp, "Unknown driver: '%s'", drvname);
3354 assert(drvname || !(flags & BDRV_O_PROTOCOL));
3356 /* See cautionary note on accessing @options above */
3357 backing = qdict_get_try_str(options, "backing");
3358 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
3359 (backing && *backing == '\0'))
3362 warn_report("Use of \"backing\": \"\" is deprecated; "
3363 "use \"backing\": null instead");
3365 flags |= BDRV_O_NO_BACKING;
3366 qdict_del(bs->explicit_options, "backing");
3367 qdict_del(bs->options, "backing");
3368 qdict_del(options, "backing");
3371 /* Open image file without format layer. This BlockBackend is only used for
3372 * probing, the block drivers will do their own bdrv_open_child() for the
3373 * same BDS, which is why we put the node name back into options. */
3374 if ((flags & BDRV_O_PROTOCOL) == 0) {
3375 BlockDriverState *file_bs;
3377 file_bs = bdrv_open_child_bs(filename, options, "file", bs,
3378 &child_of_bds, BDRV_CHILD_IMAGE,
3383 if (file_bs != NULL) {
3384 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only
3385 * looking at the header to guess the image format. This works even
3386 * in cases where a guest would not see a consistent state. */
3387 file = blk_new(bdrv_get_aio_context(file_bs), 0, BLK_PERM_ALL);
3388 blk_insert_bs(file, file_bs, &local_err);
3389 bdrv_unref(file_bs);
3394 qdict_put_str(options, "file", bdrv_get_node_name(file_bs));
3398 /* Image format probing */
3401 ret = find_image_format(file, filename, &drv, &local_err);
3406 * This option update would logically belong in bdrv_fill_options(),
3407 * but we first need to open bs->file for the probing to work, while
3408 * opening bs->file already requires the (mostly) final set of options
3409 * so that cache mode etc. can be inherited.
3411 * Adding the driver later is somewhat ugly, but it's not an option
3412 * that would ever be inherited, so it's correct. We just need to make
3413 * sure to update both bs->options (which has the full effective
3414 * options for bs) and options (which has file.* already removed).
3416 qdict_put_str(bs->options, "driver", drv->format_name);
3417 qdict_put_str(options, "driver", drv->format_name);
3419 error_setg(errp, "Must specify either driver or file");
3423 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
3424 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
3425 /* file must be NULL if a protocol BDS is about to be created
3426 * (the inverse results in an error message from bdrv_open_common()) */
3427 assert(!(flags & BDRV_O_PROTOCOL) || !file);
3429 /* Open the image */
3430 ret = bdrv_open_common(bs, file, options, &local_err);
3440 /* If there is a backing file, use it */
3441 if ((flags & BDRV_O_NO_BACKING) == 0) {
3442 ret = bdrv_open_backing_file(bs, options, "backing", &local_err);
3444 goto close_and_fail;
3448 /* Remove all children options and references
3449 * from bs->options and bs->explicit_options */
3450 QLIST_FOREACH(child, &bs->children, next) {
3451 char *child_key_dot;
3452 child_key_dot = g_strdup_printf("%s.", child->name);
3453 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot);
3454 qdict_extract_subqdict(bs->options, NULL, child_key_dot);
3455 qdict_del(bs->explicit_options, child->name);
3456 qdict_del(bs->options, child->name);
3457 g_free(child_key_dot);
3460 /* Check if any unknown options were used */
3461 if (qdict_size(options) != 0) {
3462 const QDictEntry *entry = qdict_first(options);
3463 if (flags & BDRV_O_PROTOCOL) {
3464 error_setg(errp, "Block protocol '%s' doesn't support the option "
3465 "'%s'", drv->format_name, entry->key);
3468 "Block format '%s' does not support the option '%s'",
3469 drv->format_name, entry->key);
3472 goto close_and_fail;
3475 bdrv_parent_cb_change_media(bs, true);
3477 qobject_unref(options);
3480 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
3481 * temporary snapshot afterwards. */
3482 if (snapshot_flags) {
3483 BlockDriverState *snapshot_bs;
3484 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags,
3485 snapshot_options, &local_err);
3486 snapshot_options = NULL;
3488 goto close_and_fail;
3490 /* We are not going to return bs but the overlay on top of it
3491 * (snapshot_bs); thus, we have to drop the strong reference to bs
3492 * (which we obtained by calling bdrv_new()). bs will not be deleted,
3493 * though, because the overlay still has a reference to it. */
3502 qobject_unref(snapshot_options);
3503 qobject_unref(bs->explicit_options);
3504 qobject_unref(bs->options);
3505 qobject_unref(options);
3507 bs->explicit_options = NULL;
3509 error_propagate(errp, local_err);
3514 qobject_unref(snapshot_options);
3515 qobject_unref(options);
3516 error_propagate(errp, local_err);
3520 BlockDriverState *bdrv_open(const char *filename, const char *reference,
3521 QDict *options, int flags, Error **errp)
3523 return bdrv_open_inherit(filename, reference, options, flags, NULL,
3527 /* Return true if the NULL-terminated @list contains @str */
3528 static bool is_str_in_list(const char *str, const char *const *list)
3532 for (i = 0; list[i] != NULL; i++) {
3533 if (!strcmp(str, list[i])) {
3542 * Check that every option set in @bs->options is also set in
3545 * Options listed in the common_options list and in
3546 * @bs->drv->mutable_opts are skipped.
3548 * Return 0 on success, otherwise return -EINVAL and set @errp.
3550 static int bdrv_reset_options_allowed(BlockDriverState *bs,
3551 const QDict *new_opts, Error **errp)
3553 const QDictEntry *e;
3554 /* These options are common to all block drivers and are handled
3555 * in bdrv_reopen_prepare() so they can be left out of @new_opts */
3556 const char *const common_options[] = {
3557 "node-name", "discard", "cache.direct", "cache.no-flush",
3558 "read-only", "auto-read-only", "detect-zeroes", NULL
3561 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) {
3562 if (!qdict_haskey(new_opts, e->key) &&
3563 !is_str_in_list(e->key, common_options) &&
3564 !is_str_in_list(e->key, bs->drv->mutable_opts)) {
3565 error_setg(errp, "Option '%s' cannot be reset "
3566 "to its default value", e->key);
3575 * Returns true if @child can be reached recursively from @bs
3577 static bool bdrv_recurse_has_child(BlockDriverState *bs,
3578 BlockDriverState *child)
3586 QLIST_FOREACH(c, &bs->children, next) {
3587 if (bdrv_recurse_has_child(c->bs, child)) {
3596 * Adds a BlockDriverState to a simple queue for an atomic, transactional
3597 * reopen of multiple devices.
3599 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT
3600 * already performed, or alternatively may be NULL a new BlockReopenQueue will
3601 * be created and initialized. This newly created BlockReopenQueue should be
3602 * passed back in for subsequent calls that are intended to be of the same
3605 * bs is the BlockDriverState to add to the reopen queue.
3607 * options contains the changed options for the associated bs
3608 * (the BlockReopenQueue takes ownership)
3610 * flags contains the open flags for the associated bs
3612 * returns a pointer to bs_queue, which is either the newly allocated
3613 * bs_queue, or the existing bs_queue being used.
3615 * bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple().
3617 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
3618 BlockDriverState *bs,
3620 const BdrvChildClass *klass,
3622 bool parent_is_format,
3623 QDict *parent_options,
3629 BlockReopenQueueEntry *bs_entry;
3631 QDict *old_options, *explicit_options, *options_copy;
3635 /* Make sure that the caller remembered to use a drained section. This is
3636 * important to avoid graph changes between the recursive queuing here and
3637 * bdrv_reopen_multiple(). */
3638 assert(bs->quiesce_counter > 0);
3640 if (bs_queue == NULL) {
3641 bs_queue = g_new0(BlockReopenQueue, 1);
3642 QTAILQ_INIT(bs_queue);
3646 options = qdict_new();
3649 /* Check if this BlockDriverState is already in the queue */
3650 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
3651 if (bs == bs_entry->state.bs) {
3657 * Precedence of options:
3658 * 1. Explicitly passed in options (highest)
3659 * 2. Retained from explicitly set options of bs
3660 * 3. Inherited from parent node
3661 * 4. Retained from effective options of bs
3664 /* Old explicitly set values (don't overwrite by inherited value) */
3665 if (bs_entry || keep_old_opts) {
3666 old_options = qdict_clone_shallow(bs_entry ?
3667 bs_entry->state.explicit_options :
3668 bs->explicit_options);
3669 bdrv_join_options(bs, options, old_options);
3670 qobject_unref(old_options);
3673 explicit_options = qdict_clone_shallow(options);
3675 /* Inherit from parent node */
3676 if (parent_options) {
3678 klass->inherit_options(role, parent_is_format, &flags, options,
3679 parent_flags, parent_options);
3681 flags = bdrv_get_flags(bs);
3684 if (keep_old_opts) {
3685 /* Old values are used for options that aren't set yet */
3686 old_options = qdict_clone_shallow(bs->options);
3687 bdrv_join_options(bs, options, old_options);
3688 qobject_unref(old_options);
3691 /* We have the final set of options so let's update the flags */
3692 options_copy = qdict_clone_shallow(options);
3693 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
3694 qemu_opts_absorb_qdict(opts, options_copy, NULL);
3695 update_flags_from_options(&flags, opts);
3696 qemu_opts_del(opts);
3697 qobject_unref(options_copy);
3699 /* bdrv_open_inherit() sets and clears some additional flags internally */
3700 flags &= ~BDRV_O_PROTOCOL;
3701 if (flags & BDRV_O_RDWR) {
3702 flags |= BDRV_O_ALLOW_RDWR;
3706 bs_entry = g_new0(BlockReopenQueueEntry, 1);
3707 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry);
3709 qobject_unref(bs_entry->state.options);
3710 qobject_unref(bs_entry->state.explicit_options);
3713 bs_entry->state.bs = bs;
3714 bs_entry->state.options = options;
3715 bs_entry->state.explicit_options = explicit_options;
3716 bs_entry->state.flags = flags;
3718 /* This needs to be overwritten in bdrv_reopen_prepare() */
3719 bs_entry->state.perm = UINT64_MAX;
3720 bs_entry->state.shared_perm = 0;
3723 * If keep_old_opts is false then it means that unspecified
3724 * options must be reset to their original value. We don't allow
3725 * resetting 'backing' but we need to know if the option is
3726 * missing in order to decide if we have to return an error.
3728 if (!keep_old_opts) {
3729 bs_entry->state.backing_missing =
3730 !qdict_haskey(options, "backing") &&
3731 !qdict_haskey(options, "backing.driver");
3734 QLIST_FOREACH(child, &bs->children, next) {
3735 QDict *new_child_options = NULL;
3736 bool child_keep_old = keep_old_opts;
3738 /* reopen can only change the options of block devices that were
3739 * implicitly created and inherited options. For other (referenced)
3740 * block devices, a syntax like "backing.foo" results in an error. */
3741 if (child->bs->inherits_from != bs) {
3745 /* Check if the options contain a child reference */
3746 if (qdict_haskey(options, child->name)) {
3747 const char *childref = qdict_get_try_str(options, child->name);
3749 * The current child must not be reopened if the child
3750 * reference is null or points to a different node.
3752 if (g_strcmp0(childref, child->bs->node_name)) {
3756 * If the child reference points to the current child then
3757 * reopen it with its existing set of options (note that
3758 * it can still inherit new options from the parent).
3760 child_keep_old = true;
3762 /* Extract child options ("child-name.*") */
3763 char *child_key_dot = g_strdup_printf("%s.", child->name);
3764 qdict_extract_subqdict(explicit_options, NULL, child_key_dot);
3765 qdict_extract_subqdict(options, &new_child_options, child_key_dot);
3766 g_free(child_key_dot);
3769 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
3770 child->klass, child->role, bs->drv->is_format,
3771 options, flags, child_keep_old);
3777 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
3778 BlockDriverState *bs,
3779 QDict *options, bool keep_old_opts)
3781 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false,
3782 NULL, 0, keep_old_opts);
3786 * Reopen multiple BlockDriverStates atomically & transactionally.
3788 * The queue passed in (bs_queue) must have been built up previous
3789 * via bdrv_reopen_queue().
3791 * Reopens all BDS specified in the queue, with the appropriate
3792 * flags. All devices are prepared for reopen, and failure of any
3793 * device will cause all device changes to be abandoned, and intermediate
3796 * If all devices prepare successfully, then the changes are committed
3799 * All affected nodes must be drained between bdrv_reopen_queue() and
3800 * bdrv_reopen_multiple().
3802 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
3805 BlockReopenQueueEntry *bs_entry, *next;
3807 assert(bs_queue != NULL);
3809 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
3810 assert(bs_entry->state.bs->quiesce_counter > 0);
3811 if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, errp)) {
3814 bs_entry->prepared = true;
3817 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
3818 BDRVReopenState *state = &bs_entry->state;
3819 ret = bdrv_check_perm(state->bs, bs_queue, state->perm,
3820 state->shared_perm, NULL, NULL, errp);
3824 /* Check if new_backing_bs would accept the new permissions */
3825 if (state->replace_backing_bs && state->new_backing_bs) {
3826 uint64_t nperm, nshared;
3827 bdrv_child_perm(state->bs, state->new_backing_bs,
3828 NULL, bdrv_backing_role(state->bs),
3829 bs_queue, state->perm, state->shared_perm,
3831 ret = bdrv_check_update_perm(state->new_backing_bs, NULL,
3832 nperm, nshared, NULL, NULL, errp);
3837 bs_entry->perms_checked = true;
3841 * If we reach this point, we have success and just need to apply the
3844 * Reverse order is used to comfort qcow2 driver: on commit it need to write
3845 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But
3846 * children are usually goes after parents in reopen-queue, so go from last
3849 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
3850 bdrv_reopen_commit(&bs_entry->state);
3855 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
3856 BDRVReopenState *state = &bs_entry->state;
3858 if (!bs_entry->perms_checked) {
3863 bdrv_set_perm(state->bs, state->perm, state->shared_perm);
3865 bdrv_abort_perm_update(state->bs);
3866 if (state->replace_backing_bs && state->new_backing_bs) {
3867 bdrv_abort_perm_update(state->new_backing_bs);
3873 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
3874 BlockDriverState *bs = bs_entry->state.bs;
3876 if (bs->drv->bdrv_reopen_commit_post)
3877 bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
3881 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
3883 if (bs_entry->prepared) {
3884 bdrv_reopen_abort(&bs_entry->state);
3886 qobject_unref(bs_entry->state.explicit_options);
3887 qobject_unref(bs_entry->state.options);
3889 if (bs_entry->state.new_backing_bs) {
3890 bdrv_unref(bs_entry->state.new_backing_bs);
3899 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
3903 BlockReopenQueue *queue;
3904 QDict *opts = qdict_new();
3906 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
3908 bdrv_subtree_drained_begin(bs);
3909 queue = bdrv_reopen_queue(NULL, bs, opts, true);
3910 ret = bdrv_reopen_multiple(queue, errp);
3911 bdrv_subtree_drained_end(bs);
3916 static BlockReopenQueueEntry *find_parent_in_reopen_queue(BlockReopenQueue *q,
3919 BlockReopenQueueEntry *entry;
3921 QTAILQ_FOREACH(entry, q, entry) {
3922 BlockDriverState *bs = entry->state.bs;
3925 QLIST_FOREACH(child, &bs->children, next) {
3935 static void bdrv_reopen_perm(BlockReopenQueue *q, BlockDriverState *bs,
3936 uint64_t *perm, uint64_t *shared)
3939 BlockReopenQueueEntry *parent;
3940 uint64_t cumulative_perms = 0;
3941 uint64_t cumulative_shared_perms = BLK_PERM_ALL;
3943 QLIST_FOREACH(c, &bs->parents, next_parent) {
3944 parent = find_parent_in_reopen_queue(q, c);
3946 cumulative_perms |= c->perm;
3947 cumulative_shared_perms &= c->shared_perm;
3949 uint64_t nperm, nshared;
3951 bdrv_child_perm(parent->state.bs, bs, c, c->role, q,
3952 parent->state.perm, parent->state.shared_perm,
3955 cumulative_perms |= nperm;
3956 cumulative_shared_perms &= nshared;
3959 *perm = cumulative_perms;
3960 *shared = cumulative_shared_perms;
3963 static bool bdrv_reopen_can_attach(BlockDriverState *parent,
3965 BlockDriverState *new_child,
3968 AioContext *parent_ctx = bdrv_get_aio_context(parent);
3969 AioContext *child_ctx = bdrv_get_aio_context(new_child);
3973 ignore = g_slist_prepend(NULL, child);
3974 ret = bdrv_can_set_aio_context(new_child, parent_ctx, &ignore, NULL);
3975 g_slist_free(ignore);
3980 ignore = g_slist_prepend(NULL, child);
3981 ret = bdrv_can_set_aio_context(parent, child_ctx, &ignore, errp);
3982 g_slist_free(ignore);
3987 * Take a BDRVReopenState and check if the value of 'backing' in the
3988 * reopen_state->options QDict is valid or not.
3990 * If 'backing' is missing from the QDict then return 0.
3992 * If 'backing' contains the node name of the backing file of
3993 * reopen_state->bs then return 0.
3995 * If 'backing' contains a different node name (or is null) then check
3996 * whether the current backing file can be replaced with the new one.
3997 * If that's the case then reopen_state->replace_backing_bs is set to
3998 * true and reopen_state->new_backing_bs contains a pointer to the new
3999 * backing BlockDriverState (or NULL).
4001 * Return 0 on success, otherwise return < 0 and set @errp.
4003 static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state,
4006 BlockDriverState *bs = reopen_state->bs;
4007 BlockDriverState *overlay_bs, *new_backing_bs;
4011 value = qdict_get(reopen_state->options, "backing");
4012 if (value == NULL) {
4016 switch (qobject_type(value)) {
4018 new_backing_bs = NULL;
4021 str = qobject_get_try_str(value);
4022 new_backing_bs = bdrv_lookup_bs(NULL, str, errp);
4023 if (new_backing_bs == NULL) {
4025 } else if (bdrv_recurse_has_child(new_backing_bs, bs)) {
4026 error_setg(errp, "Making '%s' a backing file of '%s' "
4027 "would create a cycle", str, bs->node_name);
4032 /* 'backing' does not allow any other data type */
4033 g_assert_not_reached();
4037 * Check AioContext compatibility so that the bdrv_set_backing_hd() call in
4038 * bdrv_reopen_commit() won't fail.
4040 if (new_backing_bs) {
4041 if (!bdrv_reopen_can_attach(bs, bs->backing, new_backing_bs, errp)) {
4047 * Find the "actual" backing file by skipping all links that point
4048 * to an implicit node, if any (e.g. a commit filter node).
4051 while (backing_bs(overlay_bs) && backing_bs(overlay_bs)->implicit) {
4052 overlay_bs = backing_bs(overlay_bs);
4055 /* If we want to replace the backing file we need some extra checks */
4056 if (new_backing_bs != backing_bs(overlay_bs)) {
4057 /* Check for implicit nodes between bs and its backing file */
4058 if (bs != overlay_bs) {
4059 error_setg(errp, "Cannot change backing link if '%s' has "
4060 "an implicit backing file", bs->node_name);
4063 /* Check if the backing link that we want to replace is frozen */
4064 if (bdrv_is_backing_chain_frozen(overlay_bs, backing_bs(overlay_bs),
4068 reopen_state->replace_backing_bs = true;
4069 if (new_backing_bs) {
4070 bdrv_ref(new_backing_bs);
4071 reopen_state->new_backing_bs = new_backing_bs;
4079 * Prepares a BlockDriverState for reopen. All changes are staged in the
4080 * 'opaque' field of the BDRVReopenState, which is used and allocated by
4081 * the block driver layer .bdrv_reopen_prepare()
4083 * bs is the BlockDriverState to reopen
4084 * flags are the new open flags
4085 * queue is the reopen queue
4087 * Returns 0 on success, non-zero on error. On error errp will be set
4090 * On failure, bdrv_reopen_abort() will be called to clean up any data.
4091 * It is the responsibility of the caller to then call the abort() or
4092 * commit() for any other BDS that have been left in a prepare() state
4095 int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
4100 Error *local_err = NULL;
4103 QDict *orig_reopen_opts;
4104 char *discard = NULL;
4106 bool drv_prepared = false;
4108 assert(reopen_state != NULL);
4109 assert(reopen_state->bs->drv != NULL);
4110 drv = reopen_state->bs->drv;
4112 /* This function and each driver's bdrv_reopen_prepare() remove
4113 * entries from reopen_state->options as they are processed, so
4114 * we need to make a copy of the original QDict. */
4115 orig_reopen_opts = qdict_clone_shallow(reopen_state->options);
4117 /* Process generic block layer options */
4118 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4119 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) {
4124 /* This was already called in bdrv_reopen_queue_child() so the flags
4125 * are up-to-date. This time we simply want to remove the options from
4126 * QemuOpts in order to indicate that they have been processed. */
4127 old_flags = reopen_state->flags;
4128 update_flags_from_options(&reopen_state->flags, opts);
4129 assert(old_flags == reopen_state->flags);
4131 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD);
4132 if (discard != NULL) {
4133 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) {
4134 error_setg(errp, "Invalid discard option");
4140 reopen_state->detect_zeroes =
4141 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err);
4143 error_propagate(errp, local_err);
4148 /* All other options (including node-name and driver) must be unchanged.
4149 * Put them back into the QDict, so that they are checked at the end
4150 * of this function. */
4151 qemu_opts_to_qdict(opts, reopen_state->options);
4153 /* If we are to stay read-only, do not allow permission change
4154 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
4155 * not set, or if the BDS still has copy_on_read enabled */
4156 read_only = !(reopen_state->flags & BDRV_O_RDWR);
4157 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
4159 error_propagate(errp, local_err);
4163 /* Calculate required permissions after reopening */
4164 bdrv_reopen_perm(queue, reopen_state->bs,
4165 &reopen_state->perm, &reopen_state->shared_perm);
4167 ret = bdrv_flush(reopen_state->bs);
4169 error_setg_errno(errp, -ret, "Error flushing drive");
4173 if (drv->bdrv_reopen_prepare) {
4175 * If a driver-specific option is missing, it means that we
4176 * should reset it to its default value.
4177 * But not all options allow that, so we need to check it first.
4179 ret = bdrv_reset_options_allowed(reopen_state->bs,
4180 reopen_state->options, errp);
4185 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
4187 if (local_err != NULL) {
4188 error_propagate(errp, local_err);
4190 bdrv_refresh_filename(reopen_state->bs);
4191 error_setg(errp, "failed while preparing to reopen image '%s'",
4192 reopen_state->bs->filename);
4197 /* It is currently mandatory to have a bdrv_reopen_prepare()
4198 * handler for each supported drv. */
4199 error_setg(errp, "Block format '%s' used by node '%s' "
4200 "does not support reopening files", drv->format_name,
4201 bdrv_get_device_or_node_name(reopen_state->bs));
4206 drv_prepared = true;
4209 * We must provide the 'backing' option if the BDS has a backing
4210 * file or if the image file has a backing file name as part of
4211 * its metadata. Otherwise the 'backing' option can be omitted.
4213 if (drv->supports_backing && reopen_state->backing_missing &&
4214 (backing_bs(reopen_state->bs) || reopen_state->bs->backing_file[0])) {
4215 error_setg(errp, "backing is missing for '%s'",
4216 reopen_state->bs->node_name);
4222 * Allow changing the 'backing' option. The new value can be
4223 * either a reference to an existing node (using its node name)
4224 * or NULL to simply detach the current backing file.
4226 ret = bdrv_reopen_parse_backing(reopen_state, errp);
4230 qdict_del(reopen_state->options, "backing");
4232 /* Options that are not handled are only okay if they are unchanged
4233 * compared to the old state. It is expected that some options are only
4234 * used for the initial open, but not reopen (e.g. filename) */
4235 if (qdict_size(reopen_state->options)) {
4236 const QDictEntry *entry = qdict_first(reopen_state->options);
4239 QObject *new = entry->value;
4240 QObject *old = qdict_get(reopen_state->bs->options, entry->key);
4242 /* Allow child references (child_name=node_name) as long as they
4243 * point to the current child (i.e. everything stays the same). */
4244 if (qobject_type(new) == QTYPE_QSTRING) {
4246 QLIST_FOREACH(child, &reopen_state->bs->children, next) {
4247 if (!strcmp(child->name, entry->key)) {
4253 const char *str = qobject_get_try_str(new);
4254 if (!strcmp(child->bs->node_name, str)) {
4255 continue; /* Found child with this name, skip option */
4261 * TODO: When using -drive to specify blockdev options, all values
4262 * will be strings; however, when using -blockdev, blockdev-add or
4263 * filenames using the json:{} pseudo-protocol, they will be
4265 * In contrast, reopening options are (currently) always strings
4266 * (because you can only specify them through qemu-io; all other
4267 * callers do not specify any options).
4268 * Therefore, when using anything other than -drive to create a BDS,
4269 * this cannot detect non-string options as unchanged, because
4270 * qobject_is_equal() always returns false for objects of different
4271 * type. In the future, this should be remedied by correctly typing
4272 * all options. For now, this is not too big of an issue because
4273 * the user can simply omit options which cannot be changed anyway,
4274 * so they will stay unchanged.
4276 if (!qobject_is_equal(new, old)) {
4277 error_setg(errp, "Cannot change the option '%s'", entry->key);
4281 } while ((entry = qdict_next(reopen_state->options, entry)));
4286 /* Restore the original reopen_state->options QDict */
4287 qobject_unref(reopen_state->options);
4288 reopen_state->options = qobject_ref(orig_reopen_opts);
4291 if (ret < 0 && drv_prepared) {
4292 /* drv->bdrv_reopen_prepare() has succeeded, so we need to
4293 * call drv->bdrv_reopen_abort() before signaling an error
4294 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort()
4295 * when the respective bdrv_reopen_prepare() has failed) */
4296 if (drv->bdrv_reopen_abort) {
4297 drv->bdrv_reopen_abort(reopen_state);
4300 qemu_opts_del(opts);
4301 qobject_unref(orig_reopen_opts);
4307 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and
4308 * makes them final by swapping the staging BlockDriverState contents into
4309 * the active BlockDriverState contents.
4311 void bdrv_reopen_commit(BDRVReopenState *reopen_state)
4314 BlockDriverState *bs;
4317 assert(reopen_state != NULL);
4318 bs = reopen_state->bs;
4320 assert(drv != NULL);
4322 /* If there are any driver level actions to take */
4323 if (drv->bdrv_reopen_commit) {
4324 drv->bdrv_reopen_commit(reopen_state);
4327 /* set BDS specific flags now */
4328 qobject_unref(bs->explicit_options);
4329 qobject_unref(bs->options);
4331 bs->explicit_options = reopen_state->explicit_options;
4332 bs->options = reopen_state->options;
4333 bs->open_flags = reopen_state->flags;
4334 bs->read_only = !(reopen_state->flags & BDRV_O_RDWR);
4335 bs->detect_zeroes = reopen_state->detect_zeroes;
4337 if (reopen_state->replace_backing_bs) {
4338 qdict_del(bs->explicit_options, "backing");
4339 qdict_del(bs->options, "backing");
4342 /* Remove child references from bs->options and bs->explicit_options.
4343 * Child options were already removed in bdrv_reopen_queue_child() */
4344 QLIST_FOREACH(child, &bs->children, next) {
4345 qdict_del(bs->explicit_options, child->name);
4346 qdict_del(bs->options, child->name);
4350 * Change the backing file if a new one was specified. We do this
4351 * after updating bs->options, so bdrv_refresh_filename() (called
4352 * from bdrv_set_backing_hd()) has the new values.
4354 if (reopen_state->replace_backing_bs) {
4355 BlockDriverState *old_backing_bs = backing_bs(bs);
4356 assert(!old_backing_bs || !old_backing_bs->implicit);
4357 /* Abort the permission update on the backing bs we're detaching */
4358 if (old_backing_bs) {
4359 bdrv_abort_perm_update(old_backing_bs);
4361 bdrv_set_backing_hd(bs, reopen_state->new_backing_bs, &error_abort);
4364 bdrv_refresh_limits(bs, NULL);
4368 * Abort the reopen, and delete and free the staged changes in
4371 void bdrv_reopen_abort(BDRVReopenState *reopen_state)
4375 assert(reopen_state != NULL);
4376 drv = reopen_state->bs->drv;
4377 assert(drv != NULL);
4379 if (drv->bdrv_reopen_abort) {
4380 drv->bdrv_reopen_abort(reopen_state);
4385 static void bdrv_close(BlockDriverState *bs)
4387 BdrvAioNotifier *ban, *ban_next;
4388 BdrvChild *child, *next;
4390 assert(!bs->refcnt);
4392 bdrv_drained_begin(bs); /* complete I/O */
4394 bdrv_drain(bs); /* in case flush left pending I/O */
4397 if (bs->drv->bdrv_close) {
4398 /* Must unfreeze all children, so bdrv_unref_child() works */
4399 bs->drv->bdrv_close(bs);
4404 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
4405 bdrv_unref_child(bs, child);
4412 atomic_set(&bs->copy_on_read, 0);
4413 bs->backing_file[0] = '\0';
4414 bs->backing_format[0] = '\0';
4415 bs->total_sectors = 0;
4416 bs->encrypted = false;
4418 qobject_unref(bs->options);
4419 qobject_unref(bs->explicit_options);
4421 bs->explicit_options = NULL;
4422 qobject_unref(bs->full_open_options);
4423 bs->full_open_options = NULL;
4425 bdrv_release_named_dirty_bitmaps(bs);
4426 assert(QLIST_EMPTY(&bs->dirty_bitmaps));
4428 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
4431 QLIST_INIT(&bs->aio_notifiers);
4432 bdrv_drained_end(bs);
4435 void bdrv_close_all(void)
4437 assert(job_next(NULL) == NULL);
4438 nbd_export_close_all();
4440 /* Drop references from requests still in flight, such as canceled block
4441 * jobs whose AIO context has not been polled yet */
4444 blk_remove_all_bs();
4445 blockdev_close_all_bdrv_states();
4447 assert(QTAILQ_EMPTY(&all_bdrv_states));
4450 static bool should_update_child(BdrvChild *c, BlockDriverState *to)
4456 if (c->klass->stay_at_node) {
4460 /* If the child @c belongs to the BDS @to, replacing the current
4461 * c->bs by @to would mean to create a loop.
4463 * Such a case occurs when appending a BDS to a backing chain.
4464 * For instance, imagine the following chain:
4466 * guest device -> node A -> further backing chain...
4468 * Now we create a new BDS B which we want to put on top of this
4469 * chain, so we first attach A as its backing node:
4474 * guest device -> node A -> further backing chain...
4476 * Finally we want to replace A by B. When doing that, we want to
4477 * replace all pointers to A by pointers to B -- except for the
4478 * pointer from B because (1) that would create a loop, and (2)
4479 * that pointer should simply stay intact:
4481 * guest device -> node B
4484 * node A -> further backing chain...
4486 * In general, when replacing a node A (c->bs) by a node B (@to),
4487 * if A is a child of B, that means we cannot replace A by B there
4488 * because that would create a loop. Silently detaching A from B
4489 * is also not really an option. So overall just leaving A in
4490 * place there is the most sensible choice.
4492 * We would also create a loop in any cases where @c is only
4493 * indirectly referenced by @to. Prevent this by returning false
4494 * if @c is found (by breadth-first search) anywhere in the whole
4499 found = g_hash_table_new(NULL, NULL);
4500 g_hash_table_add(found, to);
4501 queue = g_queue_new();
4502 g_queue_push_tail(queue, to);
4504 while (!g_queue_is_empty(queue)) {
4505 BlockDriverState *v = g_queue_pop_head(queue);
4508 QLIST_FOREACH(c2, &v->children, next) {
4514 if (g_hash_table_contains(found, c2->bs)) {
4518 g_queue_push_tail(queue, c2->bs);
4519 g_hash_table_add(found, c2->bs);
4523 g_queue_free(queue);
4524 g_hash_table_destroy(found);
4529 void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
4532 BdrvChild *c, *next;
4533 GSList *list = NULL, *p;
4534 uint64_t perm = 0, shared = BLK_PERM_ALL;
4537 /* Make sure that @from doesn't go away until we have successfully attached
4538 * all of its parents to @to. */
4541 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
4542 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to));
4543 bdrv_drained_begin(from);
4545 /* Put all parents into @list and calculate their cumulative permissions */
4546 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
4547 assert(c->bs == from);
4548 if (!should_update_child(c, to)) {
4552 error_setg(errp, "Cannot change '%s' link to '%s'",
4553 c->name, from->node_name);
4556 list = g_slist_prepend(list, c);
4558 shared &= c->shared_perm;
4561 /* Check whether the required permissions can be granted on @to, ignoring
4562 * all BdrvChild in @list so that they can't block themselves. */
4563 ret = bdrv_check_update_perm(to, NULL, perm, shared, list, NULL, errp);
4565 bdrv_abort_perm_update(to);
4569 /* Now actually perform the change. We performed the permission check for
4570 * all elements of @list at once, so set the permissions all at once at the
4572 for (p = list; p != NULL; p = p->next) {
4576 bdrv_replace_child_noperm(c, to);
4580 bdrv_get_cumulative_perm(to, &perm, &shared);
4581 bdrv_set_perm(to, perm, shared);
4585 bdrv_drained_end(from);
4590 * Add new bs contents at the top of an image chain while the chain is
4591 * live, while keeping required fields on the top layer.
4593 * This will modify the BlockDriverState fields, and swap contents
4594 * between bs_new and bs_top. Both bs_new and bs_top are modified.
4596 * bs_new must not be attached to a BlockBackend.
4598 * This function does not create any image files.
4600 * bdrv_append() takes ownership of a bs_new reference and unrefs it because
4601 * that's what the callers commonly need. bs_new will be referenced by the old
4602 * parents of bs_top after bdrv_append() returns. If the caller needs to keep a
4603 * reference of its own, it must call bdrv_ref().
4605 void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
4608 Error *local_err = NULL;
4610 bdrv_set_backing_hd(bs_new, bs_top, &local_err);
4612 error_propagate(errp, local_err);
4616 bdrv_replace_node(bs_top, bs_new, &local_err);
4618 error_propagate(errp, local_err);
4619 bdrv_set_backing_hd(bs_new, NULL, &error_abort);
4623 /* bs_new is now referenced by its new parents, we don't need the
4624 * additional reference any more. */
4629 static void bdrv_delete(BlockDriverState *bs)
4631 assert(bdrv_op_blocker_is_empty(bs));
4632 assert(!bs->refcnt);
4634 /* remove from list, if necessary */
4635 if (bs->node_name[0] != '\0') {
4636 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
4638 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
4646 * Run consistency checks on an image
4648 * Returns 0 if the check could be completed (it doesn't mean that the image is
4649 * free of errors) or -errno when an internal error occurred. The results of the
4650 * check are stored in res.
4652 static int coroutine_fn bdrv_co_check(BlockDriverState *bs,
4653 BdrvCheckResult *res, BdrvCheckMode fix)
4655 if (bs->drv == NULL) {
4658 if (bs->drv->bdrv_co_check == NULL) {
4662 memset(res, 0, sizeof(*res));
4663 return bs->drv->bdrv_co_check(bs, res, fix);
4666 typedef struct CheckCo {
4667 BlockDriverState *bs;
4668 BdrvCheckResult *res;
4673 static void coroutine_fn bdrv_check_co_entry(void *opaque)
4675 CheckCo *cco = opaque;
4676 cco->ret = bdrv_co_check(cco->bs, cco->res, cco->fix);
4680 int bdrv_check(BlockDriverState *bs,
4681 BdrvCheckResult *res, BdrvCheckMode fix)
4687 .ret = -EINPROGRESS,
4691 if (qemu_in_coroutine()) {
4692 /* Fast-path if already in coroutine context */
4693 bdrv_check_co_entry(&cco);
4695 co = qemu_coroutine_create(bdrv_check_co_entry, &cco);
4696 bdrv_coroutine_enter(bs, co);
4697 BDRV_POLL_WHILE(bs, cco.ret == -EINPROGRESS);
4706 * -EINVAL - backing format specified, but no file
4707 * -ENOSPC - can't update the backing file because no space is left in the
4709 * -ENOTSUP - format driver doesn't support changing the backing file
4711 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
4712 const char *backing_fmt, bool warn)
4714 BlockDriver *drv = bs->drv;
4721 /* Backing file format doesn't make sense without a backing file */
4722 if (backing_fmt && !backing_file) {
4726 if (warn && backing_file && !backing_fmt) {
4727 warn_report("Deprecated use of backing file without explicit "
4728 "backing format, use of this image requires "
4729 "potentially unsafe format probing");
4732 if (drv->bdrv_change_backing_file != NULL) {
4733 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
4739 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
4740 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
4741 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
4742 backing_file ?: "");
4748 * Finds the image layer in the chain that has 'bs' as its backing file.
4750 * active is the current topmost image.
4752 * Returns NULL if bs is not found in active's image chain,
4753 * or if active == bs.
4755 * Returns the bottommost base image if bs == NULL.
4757 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
4758 BlockDriverState *bs)
4760 while (active && bs != backing_bs(active)) {
4761 active = backing_bs(active);
4767 /* Given a BDS, searches for the base layer. */
4768 BlockDriverState *bdrv_find_base(BlockDriverState *bs)
4770 return bdrv_find_overlay(bs, NULL);
4774 * Return true if at least one of the COW (backing) and filter links
4775 * between @bs and @base is frozen. @errp is set if that's the case.
4776 * @base must be reachable from @bs, or NULL.
4778 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
4781 BlockDriverState *i;
4784 for (i = bs; i != base; i = child_bs(child)) {
4785 child = bdrv_filter_or_cow_child(i);
4787 if (child && child->frozen) {
4788 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
4789 child->name, i->node_name, child->bs->node_name);
4798 * Freeze all COW (backing) and filter links between @bs and @base.
4799 * If any of the links is already frozen the operation is aborted and
4800 * none of the links are modified.
4801 * @base must be reachable from @bs, or NULL.
4802 * Returns 0 on success. On failure returns < 0 and sets @errp.
4804 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
4807 BlockDriverState *i;
4810 if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
4814 for (i = bs; i != base; i = child_bs(child)) {
4815 child = bdrv_filter_or_cow_child(i);
4816 if (child && child->bs->never_freeze) {
4817 error_setg(errp, "Cannot freeze '%s' link to '%s'",
4818 child->name, child->bs->node_name);
4823 for (i = bs; i != base; i = child_bs(child)) {
4824 child = bdrv_filter_or_cow_child(i);
4826 child->frozen = true;
4834 * Unfreeze all COW (backing) and filter links between @bs and @base.
4835 * The caller must ensure that all links are frozen before using this
4837 * @base must be reachable from @bs, or NULL.
4839 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
4841 BlockDriverState *i;
4844 for (i = bs; i != base; i = child_bs(child)) {
4845 child = bdrv_filter_or_cow_child(i);
4847 assert(child->frozen);
4848 child->frozen = false;
4854 * Drops images above 'base' up to and including 'top', and sets the image
4855 * above 'top' to have base as its backing file.
4857 * Requires that the overlay to 'top' is opened r/w, so that the backing file
4858 * information in 'bs' can be properly updated.
4860 * E.g., this will convert the following chain:
4861 * bottom <- base <- intermediate <- top <- active
4865 * bottom <- base <- active
4867 * It is allowed for bottom==base, in which case it converts:
4869 * base <- intermediate <- top <- active
4875 * If backing_file_str is non-NULL, it will be used when modifying top's
4876 * overlay image metadata.
4879 * if active == top, that is considered an error
4882 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
4883 const char *backing_file_str)
4885 BlockDriverState *explicit_top = top;
4886 bool update_inherits_from;
4887 BdrvChild *c, *next;
4888 Error *local_err = NULL;
4892 bdrv_subtree_drained_begin(top);
4894 if (!top->drv || !base->drv) {
4898 /* Make sure that base is in the backing chain of top */
4899 if (!bdrv_chain_contains(top, base)) {
4903 /* This function changes all links that point to top and makes
4904 * them point to base. Check that none of them is frozen. */
4905 QLIST_FOREACH(c, &top->parents, next_parent) {
4911 /* If 'base' recursively inherits from 'top' then we should set
4912 * base->inherits_from to top->inherits_from after 'top' and all
4913 * other intermediate nodes have been dropped.
4914 * If 'top' is an implicit node (e.g. "commit_top") we should skip
4915 * it because no one inherits from it. We use explicit_top for that. */
4916 while (explicit_top && explicit_top->implicit) {
4917 explicit_top = backing_bs(explicit_top);
4919 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
4921 /* success - we can delete the intermediate states, and link top->base */
4922 /* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once
4923 * we've figured out how they should work. */
4924 if (!backing_file_str) {
4925 bdrv_refresh_filename(base);
4926 backing_file_str = base->filename;
4929 QLIST_FOREACH_SAFE(c, &top->parents, next_parent, next) {
4930 /* Check whether we are allowed to switch c from top to base */
4931 GSList *ignore_children = g_slist_prepend(NULL, c);
4932 ret = bdrv_check_update_perm(base, NULL, c->perm, c->shared_perm,
4933 ignore_children, NULL, &local_err);
4934 g_slist_free(ignore_children);
4936 error_report_err(local_err);
4940 /* If so, update the backing file path in the image file */
4941 if (c->klass->update_filename) {
4942 ret = c->klass->update_filename(c, base, backing_file_str,
4945 bdrv_abort_perm_update(base);
4946 error_report_err(local_err);
4952 * Do the actual switch in the in-memory graph.
4953 * Completes bdrv_check_update_perm() transaction internally.
4954 * c->frozen is false, we have checked that above.
4957 bdrv_replace_child(c, base);
4961 if (update_inherits_from) {
4962 base->inherits_from = explicit_top->inherits_from;
4967 bdrv_subtree_drained_end(top);
4973 * Length of a allocated file in bytes. Sparse files are counted by actual
4974 * allocated space. Return < 0 if error or unknown.
4976 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs)
4978 BlockDriver *drv = bs->drv;
4982 if (drv->bdrv_get_allocated_file_size) {
4983 return drv->bdrv_get_allocated_file_size(bs);
4986 return bdrv_get_allocated_file_size(bs->file->bs);
4993 * @drv: Format driver
4994 * @opts: Creation options for new image
4995 * @in_bs: Existing image containing data for new image (may be NULL)
4996 * @errp: Error object
4997 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
5000 * Calculate file size required to create a new image.
5002 * If @in_bs is given then space for allocated clusters and zero clusters
5003 * from that image are included in the calculation. If @opts contains a
5004 * backing file that is shared by @in_bs then backing clusters may be omitted
5005 * from the calculation.
5007 * If @in_bs is NULL then the calculation includes no allocated clusters
5008 * unless a preallocation option is given in @opts.
5010 * Note that @in_bs may use a different BlockDriver from @drv.
5012 * If an error occurs the @errp pointer is set.
5014 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
5015 BlockDriverState *in_bs, Error **errp)
5017 if (!drv->bdrv_measure) {
5018 error_setg(errp, "Block driver '%s' does not support size measurement",
5023 return drv->bdrv_measure(opts, in_bs, errp);
5027 * Return number of sectors on success, -errno on error.
5029 int64_t bdrv_nb_sectors(BlockDriverState *bs)
5031 BlockDriver *drv = bs->drv;
5036 if (drv->has_variable_length) {
5037 int ret = refresh_total_sectors(bs, bs->total_sectors);
5042 return bs->total_sectors;
5046 * Return length in bytes on success, -errno on error.
5047 * The length is always a multiple of BDRV_SECTOR_SIZE.
5049 int64_t bdrv_getlength(BlockDriverState *bs)
5051 int64_t ret = bdrv_nb_sectors(bs);
5053 ret = ret > INT64_MAX / BDRV_SECTOR_SIZE ? -EFBIG : ret;
5054 return ret < 0 ? ret : ret * BDRV_SECTOR_SIZE;
5057 /* return 0 as number of sectors if no device present or error */
5058 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
5060 int64_t nb_sectors = bdrv_nb_sectors(bs);
5062 *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
5065 bool bdrv_is_sg(BlockDriverState *bs)
5071 * Return whether the given node supports compressed writes.
5073 bool bdrv_supports_compressed_writes(BlockDriverState *bs)
5075 BlockDriverState *filtered;
5077 if (!bs->drv || !block_driver_can_compress(bs->drv)) {
5081 filtered = bdrv_filter_bs(bs);
5084 * Filters can only forward compressed writes, so we have to
5087 return bdrv_supports_compressed_writes(filtered);
5093 const char *bdrv_get_format_name(BlockDriverState *bs)
5095 return bs->drv ? bs->drv->format_name : NULL;
5098 static int qsort_strcmp(const void *a, const void *b)
5100 return strcmp(*(char *const *)a, *(char *const *)b);
5103 void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
5104 void *opaque, bool read_only)
5109 const char **formats = NULL;
5111 QLIST_FOREACH(drv, &bdrv_drivers, list) {
5112 if (drv->format_name) {
5116 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) {
5120 while (formats && i && !found) {
5121 found = !strcmp(formats[--i], drv->format_name);
5125 formats = g_renew(const char *, formats, count + 1);
5126 formats[count++] = drv->format_name;
5131 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) {
5132 const char *format_name = block_driver_modules[i].format_name;
5138 if (use_bdrv_whitelist &&
5139 !bdrv_format_is_whitelisted(format_name, read_only)) {
5143 while (formats && j && !found) {
5144 found = !strcmp(formats[--j], format_name);
5148 formats = g_renew(const char *, formats, count + 1);
5149 formats[count++] = format_name;
5154 qsort(formats, count, sizeof(formats[0]), qsort_strcmp);
5156 for (i = 0; i < count; i++) {
5157 it(opaque, formats[i]);
5163 /* This function is to find a node in the bs graph */
5164 BlockDriverState *bdrv_find_node(const char *node_name)
5166 BlockDriverState *bs;
5170 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5171 if (!strcmp(node_name, bs->node_name)) {
5178 /* Put this QMP function here so it can access the static graph_bdrv_states. */
5179 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
5182 BlockDeviceInfoList *list, *entry;
5183 BlockDriverState *bs;
5186 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5187 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
5189 qapi_free_BlockDeviceInfoList(list);
5192 entry = g_malloc0(sizeof(*entry));
5193 entry->value = info;
5201 #define QAPI_LIST_ADD(list, element) do { \
5202 typeof(list) _tmp = g_new(typeof(*(list)), 1); \
5203 _tmp->value = (element); \
5204 _tmp->next = (list); \
5208 typedef struct XDbgBlockGraphConstructor {
5209 XDbgBlockGraph *graph;
5210 GHashTable *graph_nodes;
5211 } XDbgBlockGraphConstructor;
5213 static XDbgBlockGraphConstructor *xdbg_graph_new(void)
5215 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1);
5217 gr->graph = g_new0(XDbgBlockGraph, 1);
5218 gr->graph_nodes = g_hash_table_new(NULL, NULL);
5223 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr)
5225 XDbgBlockGraph *graph = gr->graph;
5227 g_hash_table_destroy(gr->graph_nodes);
5233 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node)
5235 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node);
5242 * Start counting from 1, not 0, because 0 interferes with not-found (NULL)
5243 * answer of g_hash_table_lookup.
5245 ret = g_hash_table_size(gr->graph_nodes) + 1;
5246 g_hash_table_insert(gr->graph_nodes, node, (void *)ret);
5251 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node,
5252 XDbgBlockGraphNodeType type, const char *name)
5254 XDbgBlockGraphNode *n;
5256 n = g_new0(XDbgBlockGraphNode, 1);
5258 n->id = xdbg_graph_node_num(gr, node);
5260 n->name = g_strdup(name);
5262 QAPI_LIST_ADD(gr->graph->nodes, n);
5265 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent,
5266 const BdrvChild *child)
5268 BlockPermission qapi_perm;
5269 XDbgBlockGraphEdge *edge;
5271 edge = g_new0(XDbgBlockGraphEdge, 1);
5273 edge->parent = xdbg_graph_node_num(gr, parent);
5274 edge->child = xdbg_graph_node_num(gr, child->bs);
5275 edge->name = g_strdup(child->name);
5277 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) {
5278 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm);
5280 if (flag & child->perm) {
5281 QAPI_LIST_ADD(edge->perm, qapi_perm);
5283 if (flag & child->shared_perm) {
5284 QAPI_LIST_ADD(edge->shared_perm, qapi_perm);
5288 QAPI_LIST_ADD(gr->graph->edges, edge);
5292 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp)
5296 BlockDriverState *bs;
5298 XDbgBlockGraphConstructor *gr = xdbg_graph_new();
5300 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
5301 char *allocated_name = NULL;
5302 const char *name = blk_name(blk);
5305 name = allocated_name = blk_get_attached_dev_id(blk);
5307 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND,
5309 g_free(allocated_name);
5310 if (blk_root(blk)) {
5311 xdbg_graph_add_edge(gr, blk, blk_root(blk));
5315 for (job = block_job_next(NULL); job; job = block_job_next(job)) {
5318 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB,
5320 for (el = job->nodes; el; el = el->next) {
5321 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data);
5325 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5326 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER,
5328 QLIST_FOREACH(child, &bs->children, next) {
5329 xdbg_graph_add_edge(gr, bs, child);
5333 return xdbg_graph_finalize(gr);
5336 BlockDriverState *bdrv_lookup_bs(const char *device,
5337 const char *node_name,
5341 BlockDriverState *bs;
5344 blk = blk_by_name(device);
5349 error_setg(errp, "Device '%s' has no medium", device);
5357 bs = bdrv_find_node(node_name);
5364 error_setg(errp, "Cannot find device=%s nor node_name=%s",
5365 device ? device : "",
5366 node_name ? node_name : "");
5370 /* If 'base' is in the same chain as 'top', return true. Otherwise,
5371 * return false. If either argument is NULL, return false. */
5372 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
5374 while (top && top != base) {
5375 top = backing_bs(top);
5381 BlockDriverState *bdrv_next_node(BlockDriverState *bs)
5384 return QTAILQ_FIRST(&graph_bdrv_states);
5386 return QTAILQ_NEXT(bs, node_list);
5389 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs)
5392 return QTAILQ_FIRST(&all_bdrv_states);
5394 return QTAILQ_NEXT(bs, bs_list);
5397 const char *bdrv_get_node_name(const BlockDriverState *bs)
5399 return bs->node_name;
5402 const char *bdrv_get_parent_name(const BlockDriverState *bs)
5407 /* If multiple parents have a name, just pick the first one. */
5408 QLIST_FOREACH(c, &bs->parents, next_parent) {
5409 if (c->klass->get_name) {
5410 name = c->klass->get_name(c);
5411 if (name && *name) {
5420 /* TODO check what callers really want: bs->node_name or blk_name() */
5421 const char *bdrv_get_device_name(const BlockDriverState *bs)
5423 return bdrv_get_parent_name(bs) ?: "";
5426 /* This can be used to identify nodes that might not have a device
5427 * name associated. Since node and device names live in the same
5428 * namespace, the result is unambiguous. The exception is if both are
5429 * absent, then this returns an empty (non-null) string. */
5430 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
5432 return bdrv_get_parent_name(bs) ?: bs->node_name;
5435 int bdrv_get_flags(BlockDriverState *bs)
5437 return bs->open_flags;
5440 int bdrv_has_zero_init_1(BlockDriverState *bs)
5445 int bdrv_has_zero_init(BlockDriverState *bs)
5447 BlockDriverState *filtered;
5453 /* If BS is a copy on write image, it is initialized to
5454 the contents of the base image, which may not be zeroes. */
5455 if (bdrv_cow_child(bs)) {
5458 if (bs->drv->bdrv_has_zero_init) {
5459 return bs->drv->bdrv_has_zero_init(bs);
5462 filtered = bdrv_filter_bs(bs);
5464 return bdrv_has_zero_init(filtered);
5471 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
5473 if (!(bs->open_flags & BDRV_O_UNMAP)) {
5477 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
5480 void bdrv_get_backing_filename(BlockDriverState *bs,
5481 char *filename, int filename_size)
5483 pstrcpy(filename, filename_size, bs->backing_file);
5486 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
5488 BlockDriver *drv = bs->drv;
5489 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
5493 if (!drv->bdrv_get_info) {
5494 BlockDriverState *filtered = bdrv_filter_bs(bs);
5496 return bdrv_get_info(filtered, bdi);
5500 memset(bdi, 0, sizeof(*bdi));
5501 return drv->bdrv_get_info(bs, bdi);
5504 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
5507 BlockDriver *drv = bs->drv;
5508 if (drv && drv->bdrv_get_specific_info) {
5509 return drv->bdrv_get_specific_info(bs, errp);
5514 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs)
5516 BlockDriver *drv = bs->drv;
5517 if (!drv || !drv->bdrv_get_specific_stats) {
5520 return drv->bdrv_get_specific_stats(bs);
5523 void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event)
5525 if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) {
5529 bs->drv->bdrv_debug_event(bs, event);
5532 static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs)
5534 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
5540 if (bs->drv->is_filter && bs->backing) {
5541 bs = bs->backing->bs;
5548 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
5549 assert(bs->drv->bdrv_debug_remove_breakpoint);
5556 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event,
5559 bs = bdrv_find_debug_node(bs);
5561 return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
5567 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
5569 bs = bdrv_find_debug_node(bs);
5571 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
5577 int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
5579 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
5580 bs = bs->file ? bs->file->bs : NULL;
5583 if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
5584 return bs->drv->bdrv_debug_resume(bs, tag);
5590 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
5592 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
5593 bs = bs->file ? bs->file->bs : NULL;
5596 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
5597 return bs->drv->bdrv_debug_is_suspended(bs, tag);
5603 /* backing_file can either be relative, or absolute, or a protocol. If it is
5604 * relative, it must be relative to the chain. So, passing in bs->filename
5605 * from a BDS as backing_file should not be done, as that may be relative to
5606 * the CWD rather than the chain. */
5607 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
5608 const char *backing_file)
5610 char *filename_full = NULL;
5611 char *backing_file_full = NULL;
5612 char *filename_tmp = NULL;
5613 int is_protocol = 0;
5614 BlockDriverState *curr_bs = NULL;
5615 BlockDriverState *retval = NULL;
5617 if (!bs || !bs->drv || !backing_file) {
5621 filename_full = g_malloc(PATH_MAX);
5622 backing_file_full = g_malloc(PATH_MAX);
5624 is_protocol = path_has_protocol(backing_file);
5626 for (curr_bs = bs; curr_bs->backing; curr_bs = curr_bs->backing->bs) {
5628 /* If either of the filename paths is actually a protocol, then
5629 * compare unmodified paths; otherwise make paths relative */
5630 if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
5631 char *backing_file_full_ret;
5633 if (strcmp(backing_file, curr_bs->backing_file) == 0) {
5634 retval = curr_bs->backing->bs;
5637 /* Also check against the full backing filename for the image */
5638 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs,
5640 if (backing_file_full_ret) {
5641 bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
5642 g_free(backing_file_full_ret);
5644 retval = curr_bs->backing->bs;
5649 /* If not an absolute filename path, make it relative to the current
5650 * image's filename path */
5651 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
5653 /* We are going to compare canonicalized absolute pathnames */
5654 if (!filename_tmp || !realpath(filename_tmp, filename_full)) {
5655 g_free(filename_tmp);
5658 g_free(filename_tmp);
5660 /* We need to make sure the backing filename we are comparing against
5661 * is relative to the current image filename (or absolute) */
5662 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
5663 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) {
5664 g_free(filename_tmp);
5667 g_free(filename_tmp);
5669 if (strcmp(backing_file_full, filename_full) == 0) {
5670 retval = curr_bs->backing->bs;
5676 g_free(filename_full);
5677 g_free(backing_file_full);
5681 void bdrv_init(void)
5683 module_call_init(MODULE_INIT_BLOCK);
5686 void bdrv_init_with_whitelist(void)
5688 use_bdrv_whitelist = 1;
5692 static void coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs,
5695 BdrvChild *child, *parent;
5696 uint64_t perm, shared_perm;
5697 Error *local_err = NULL;
5699 BdrvDirtyBitmap *bm;
5705 QLIST_FOREACH(child, &bs->children, next) {
5706 bdrv_co_invalidate_cache(child->bs, &local_err);
5708 error_propagate(errp, local_err);
5714 * Update permissions, they may differ for inactive nodes.
5716 * Note that the required permissions of inactive images are always a
5717 * subset of the permissions required after activating the image. This
5718 * allows us to just get the permissions upfront without restricting
5719 * drv->bdrv_invalidate_cache().
5721 * It also means that in error cases, we don't have to try and revert to
5722 * the old permissions (which is an operation that could fail, too). We can
5723 * just keep the extended permissions for the next time that an activation
5724 * of the image is tried.
5726 if (bs->open_flags & BDRV_O_INACTIVE) {
5727 bs->open_flags &= ~BDRV_O_INACTIVE;
5728 bdrv_get_cumulative_perm(bs, &perm, &shared_perm);
5729 ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, errp);
5731 bs->open_flags |= BDRV_O_INACTIVE;
5734 bdrv_set_perm(bs, perm, shared_perm);
5736 if (bs->drv->bdrv_co_invalidate_cache) {
5737 bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
5739 bs->open_flags |= BDRV_O_INACTIVE;
5740 error_propagate(errp, local_err);
5745 FOR_EACH_DIRTY_BITMAP(bs, bm) {
5746 bdrv_dirty_bitmap_skip_store(bm, false);
5749 ret = refresh_total_sectors(bs, bs->total_sectors);
5751 bs->open_flags |= BDRV_O_INACTIVE;
5752 error_setg_errno(errp, -ret, "Could not refresh total sector count");
5757 QLIST_FOREACH(parent, &bs->parents, next_parent) {
5758 if (parent->klass->activate) {
5759 parent->klass->activate(parent, &local_err);
5761 bs->open_flags |= BDRV_O_INACTIVE;
5762 error_propagate(errp, local_err);
5769 typedef struct InvalidateCacheCo {
5770 BlockDriverState *bs;
5773 } InvalidateCacheCo;
5775 static void coroutine_fn bdrv_invalidate_cache_co_entry(void *opaque)
5777 InvalidateCacheCo *ico = opaque;
5778 bdrv_co_invalidate_cache(ico->bs, ico->errp);
5783 void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
5786 InvalidateCacheCo ico = {
5792 if (qemu_in_coroutine()) {
5793 /* Fast-path if already in coroutine context */
5794 bdrv_invalidate_cache_co_entry(&ico);
5796 co = qemu_coroutine_create(bdrv_invalidate_cache_co_entry, &ico);
5797 bdrv_coroutine_enter(bs, co);
5798 BDRV_POLL_WHILE(bs, !ico.done);
5802 void bdrv_invalidate_cache_all(Error **errp)
5804 BlockDriverState *bs;
5805 Error *local_err = NULL;
5806 BdrvNextIterator it;
5808 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
5809 AioContext *aio_context = bdrv_get_aio_context(bs);
5811 aio_context_acquire(aio_context);
5812 bdrv_invalidate_cache(bs, &local_err);
5813 aio_context_release(aio_context);
5815 error_propagate(errp, local_err);
5816 bdrv_next_cleanup(&it);
5822 static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
5826 QLIST_FOREACH(parent, &bs->parents, next_parent) {
5827 if (parent->klass->parent_is_bds) {
5828 BlockDriverState *parent_bs = parent->opaque;
5829 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) {
5838 static int bdrv_inactivate_recurse(BlockDriverState *bs)
5840 BdrvChild *child, *parent;
5841 bool tighten_restrictions;
5842 uint64_t perm, shared_perm;
5849 /* Make sure that we don't inactivate a child before its parent.
5850 * It will be covered by recursion from the yet active parent. */
5851 if (bdrv_has_bds_parent(bs, true)) {
5855 assert(!(bs->open_flags & BDRV_O_INACTIVE));
5857 /* Inactivate this node */
5858 if (bs->drv->bdrv_inactivate) {
5859 ret = bs->drv->bdrv_inactivate(bs);
5865 QLIST_FOREACH(parent, &bs->parents, next_parent) {
5866 if (parent->klass->inactivate) {
5867 ret = parent->klass->inactivate(parent);
5874 bs->open_flags |= BDRV_O_INACTIVE;
5876 /* Update permissions, they may differ for inactive nodes */
5877 bdrv_get_cumulative_perm(bs, &perm, &shared_perm);
5878 ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL,
5879 &tighten_restrictions, NULL);
5880 assert(tighten_restrictions == false);
5882 /* We only tried to loosen restrictions, so errors are not fatal */
5883 bdrv_abort_perm_update(bs);
5885 bdrv_set_perm(bs, perm, shared_perm);
5889 /* Recursively inactivate children */
5890 QLIST_FOREACH(child, &bs->children, next) {
5891 ret = bdrv_inactivate_recurse(child->bs);
5900 int bdrv_inactivate_all(void)
5902 BlockDriverState *bs = NULL;
5903 BdrvNextIterator it;
5905 GSList *aio_ctxs = NULL, *ctx;
5907 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
5908 AioContext *aio_context = bdrv_get_aio_context(bs);
5910 if (!g_slist_find(aio_ctxs, aio_context)) {
5911 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
5912 aio_context_acquire(aio_context);
5916 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
5917 /* Nodes with BDS parents are covered by recursion from the last
5918 * parent that gets inactivated. Don't inactivate them a second
5919 * time if that has already happened. */
5920 if (bdrv_has_bds_parent(bs, false)) {
5923 ret = bdrv_inactivate_recurse(bs);
5925 bdrv_next_cleanup(&it);
5931 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
5932 AioContext *aio_context = ctx->data;
5933 aio_context_release(aio_context);
5935 g_slist_free(aio_ctxs);
5940 /**************************************************************/
5941 /* removable device support */
5944 * Return TRUE if the media is present
5946 bool bdrv_is_inserted(BlockDriverState *bs)
5948 BlockDriver *drv = bs->drv;
5954 if (drv->bdrv_is_inserted) {
5955 return drv->bdrv_is_inserted(bs);
5957 QLIST_FOREACH(child, &bs->children, next) {
5958 if (!bdrv_is_inserted(child->bs)) {
5966 * If eject_flag is TRUE, eject the media. Otherwise, close the tray
5968 void bdrv_eject(BlockDriverState *bs, bool eject_flag)
5970 BlockDriver *drv = bs->drv;
5972 if (drv && drv->bdrv_eject) {
5973 drv->bdrv_eject(bs, eject_flag);
5978 * Lock or unlock the media (if it is locked, the user won't be able
5979 * to eject it manually).
5981 void bdrv_lock_medium(BlockDriverState *bs, bool locked)
5983 BlockDriver *drv = bs->drv;
5985 trace_bdrv_lock_medium(bs, locked);
5987 if (drv && drv->bdrv_lock_medium) {
5988 drv->bdrv_lock_medium(bs, locked);
5992 /* Get a reference to bs */
5993 void bdrv_ref(BlockDriverState *bs)
5998 /* Release a previously grabbed reference to bs.
5999 * If after releasing, reference count is zero, the BlockDriverState is
6001 void bdrv_unref(BlockDriverState *bs)
6006 assert(bs->refcnt > 0);
6007 if (--bs->refcnt == 0) {
6012 struct BdrvOpBlocker {
6014 QLIST_ENTRY(BdrvOpBlocker) list;
6017 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
6019 BdrvOpBlocker *blocker;
6020 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6021 if (!QLIST_EMPTY(&bs->op_blockers[op])) {
6022 blocker = QLIST_FIRST(&bs->op_blockers[op]);
6023 error_propagate_prepend(errp, error_copy(blocker->reason),
6024 "Node '%s' is busy: ",
6025 bdrv_get_device_or_node_name(bs));
6031 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
6033 BdrvOpBlocker *blocker;
6034 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6036 blocker = g_new0(BdrvOpBlocker, 1);
6037 blocker->reason = reason;
6038 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
6041 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
6043 BdrvOpBlocker *blocker, *next;
6044 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6045 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
6046 if (blocker->reason == reason) {
6047 QLIST_REMOVE(blocker, list);
6053 void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
6056 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6057 bdrv_op_block(bs, i, reason);
6061 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
6064 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6065 bdrv_op_unblock(bs, i, reason);
6069 bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
6073 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6074 if (!QLIST_EMPTY(&bs->op_blockers[i])) {
6081 void bdrv_img_create(const char *filename, const char *fmt,
6082 const char *base_filename, const char *base_fmt,
6083 char *options, uint64_t img_size, int flags, bool quiet,
6086 QemuOptsList *create_opts = NULL;
6087 QemuOpts *opts = NULL;
6088 const char *backing_fmt, *backing_file;
6090 BlockDriver *drv, *proto_drv;
6091 Error *local_err = NULL;
6094 /* Find driver and parse its options */
6095 drv = bdrv_find_format(fmt);
6097 error_setg(errp, "Unknown file format '%s'", fmt);
6101 proto_drv = bdrv_find_protocol(filename, true, errp);
6106 if (!drv->create_opts) {
6107 error_setg(errp, "Format driver '%s' does not support image creation",
6112 if (!proto_drv->create_opts) {
6113 error_setg(errp, "Protocol driver '%s' does not support image creation",
6114 proto_drv->format_name);
6118 /* Create parameter list */
6119 create_opts = qemu_opts_append(create_opts, drv->create_opts);
6120 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
6122 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
6124 /* Parse -o options */
6126 if (!qemu_opts_do_parse(opts, options, NULL, errp)) {
6131 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) {
6132 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort);
6133 } else if (img_size != UINT64_C(-1)) {
6134 error_setg(errp, "The image size must be specified only once");
6138 if (base_filename) {
6139 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename,
6141 error_setg(errp, "Backing file not supported for file format '%s'",
6148 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) {
6149 error_setg(errp, "Backing file format not supported for file "
6150 "format '%s'", fmt);
6155 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
6157 if (!strcmp(filename, backing_file)) {
6158 error_setg(errp, "Error: Trying to create an image with the "
6159 "same filename as the backing file");
6162 if (backing_file[0] == '\0') {
6163 error_setg(errp, "Expected backing file name, got empty string");
6168 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
6170 /* The size for the image must always be specified, unless we have a backing
6171 * file and we have not been forbidden from opening it. */
6172 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
6173 if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
6174 BlockDriverState *bs;
6177 QDict *backing_options = NULL;
6180 bdrv_get_full_backing_filename_from_filename(filename, backing_file,
6185 assert(full_backing);
6187 /* backing files always opened read-only */
6189 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
6191 backing_options = qdict_new();
6193 qdict_put_str(backing_options, "driver", backing_fmt);
6195 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
6197 bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
6199 g_free(full_backing);
6201 error_append_hint(&local_err, "Could not open backing image.\n");
6205 warn_report("Deprecated use of backing file without explicit "
6206 "backing format (detected format of %s)",
6207 bs->drv->format_name);
6208 if (bs->drv != &bdrv_raw) {
6210 * A probe of raw deserves the most attention:
6211 * leaving the backing format out of the image
6212 * will ensure bs->probed is set (ensuring we
6213 * don't accidentally commit into the backing
6214 * file), and allow more spots to warn the users
6215 * to fix their toolchain when opening this image
6216 * later. For other images, we can safely record
6217 * the format that we probed.
6219 backing_fmt = bs->drv->format_name;
6220 qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, backing_fmt,
6225 /* Opened BS, have no size */
6226 size = bdrv_getlength(bs);
6228 error_setg_errno(errp, -size, "Could not get size of '%s'",
6233 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
6237 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
6238 } else if (backing_file && !backing_fmt) {
6239 warn_report("Deprecated use of unopened backing file without "
6240 "explicit backing format, use of this image requires "
6241 "potentially unsafe format probing");
6245 error_setg(errp, "Image creation needs a size parameter");
6250 printf("Formatting '%s', fmt=%s ", filename, fmt);
6251 qemu_opts_print(opts, " ");
6256 ret = bdrv_create(drv, filename, opts, &local_err);
6258 if (ret == -EFBIG) {
6259 /* This is generally a better message than whatever the driver would
6260 * deliver (especially because of the cluster_size_hint), since that
6261 * is most probably not much different from "image too large". */
6262 const char *cluster_size_hint = "";
6263 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) {
6264 cluster_size_hint = " (try using a larger cluster size)";
6266 error_setg(errp, "The image size is too large for file format '%s'"
6267 "%s", fmt, cluster_size_hint);
6268 error_free(local_err);
6273 qemu_opts_del(opts);
6274 qemu_opts_free(create_opts);
6275 error_propagate(errp, local_err);
6278 AioContext *bdrv_get_aio_context(BlockDriverState *bs)
6280 return bs ? bs->aio_context : qemu_get_aio_context();
6283 void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co)
6285 aio_co_enter(bdrv_get_aio_context(bs), co);
6288 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
6290 QLIST_REMOVE(ban, list);
6294 static void bdrv_detach_aio_context(BlockDriverState *bs)
6296 BdrvAioNotifier *baf, *baf_tmp;
6298 assert(!bs->walking_aio_notifiers);
6299 bs->walking_aio_notifiers = true;
6300 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
6302 bdrv_do_remove_aio_context_notifier(baf);
6304 baf->detach_aio_context(baf->opaque);
6307 /* Never mind iterating again to check for ->deleted. bdrv_close() will
6308 * remove remaining aio notifiers if we aren't called again.
6310 bs->walking_aio_notifiers = false;
6312 if (bs->drv && bs->drv->bdrv_detach_aio_context) {
6313 bs->drv->bdrv_detach_aio_context(bs);
6316 if (bs->quiesce_counter) {
6317 aio_enable_external(bs->aio_context);
6319 bs->aio_context = NULL;
6322 static void bdrv_attach_aio_context(BlockDriverState *bs,
6323 AioContext *new_context)
6325 BdrvAioNotifier *ban, *ban_tmp;
6327 if (bs->quiesce_counter) {
6328 aio_disable_external(new_context);
6331 bs->aio_context = new_context;
6333 if (bs->drv && bs->drv->bdrv_attach_aio_context) {
6334 bs->drv->bdrv_attach_aio_context(bs, new_context);
6337 assert(!bs->walking_aio_notifiers);
6338 bs->walking_aio_notifiers = true;
6339 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) {
6341 bdrv_do_remove_aio_context_notifier(ban);
6343 ban->attached_aio_context(new_context, ban->opaque);
6346 bs->walking_aio_notifiers = false;
6350 * Changes the AioContext used for fd handlers, timers, and BHs by this
6351 * BlockDriverState and all its children and parents.
6353 * Must be called from the main AioContext.
6355 * The caller must own the AioContext lock for the old AioContext of bs, but it
6356 * must not own the AioContext lock for new_context (unless new_context is the
6357 * same as the current context of bs).
6359 * @ignore will accumulate all visited BdrvChild object. The caller is
6360 * responsible for freeing the list afterwards.
6362 void bdrv_set_aio_context_ignore(BlockDriverState *bs,
6363 AioContext *new_context, GSList **ignore)
6365 AioContext *old_context = bdrv_get_aio_context(bs);
6368 g_assert(qemu_get_current_aio_context() == qemu_get_aio_context());
6370 if (old_context == new_context) {
6374 bdrv_drained_begin(bs);
6376 QLIST_FOREACH(child, &bs->children, next) {
6377 if (g_slist_find(*ignore, child)) {
6380 *ignore = g_slist_prepend(*ignore, child);
6381 bdrv_set_aio_context_ignore(child->bs, new_context, ignore);
6383 QLIST_FOREACH(child, &bs->parents, next_parent) {
6384 if (g_slist_find(*ignore, child)) {
6387 assert(child->klass->set_aio_ctx);
6388 *ignore = g_slist_prepend(*ignore, child);
6389 child->klass->set_aio_ctx(child, new_context, ignore);
6392 bdrv_detach_aio_context(bs);
6394 /* Acquire the new context, if necessary */
6395 if (qemu_get_aio_context() != new_context) {
6396 aio_context_acquire(new_context);
6399 bdrv_attach_aio_context(bs, new_context);
6402 * If this function was recursively called from
6403 * bdrv_set_aio_context_ignore(), there may be nodes in the
6404 * subtree that have not yet been moved to the new AioContext.
6405 * Release the old one so bdrv_drained_end() can poll them.
6407 if (qemu_get_aio_context() != old_context) {
6408 aio_context_release(old_context);
6411 bdrv_drained_end(bs);
6413 if (qemu_get_aio_context() != old_context) {
6414 aio_context_acquire(old_context);
6416 if (qemu_get_aio_context() != new_context) {
6417 aio_context_release(new_context);
6421 static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx,
6422 GSList **ignore, Error **errp)
6424 if (g_slist_find(*ignore, c)) {
6427 *ignore = g_slist_prepend(*ignore, c);
6430 * A BdrvChildClass that doesn't handle AioContext changes cannot
6431 * tolerate any AioContext changes
6433 if (!c->klass->can_set_aio_ctx) {
6434 char *user = bdrv_child_user_desc(c);
6435 error_setg(errp, "Changing iothreads is not supported by %s", user);
6439 if (!c->klass->can_set_aio_ctx(c, ctx, ignore, errp)) {
6440 assert(!errp || *errp);
6446 bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
6447 GSList **ignore, Error **errp)
6449 if (g_slist_find(*ignore, c)) {
6452 *ignore = g_slist_prepend(*ignore, c);
6453 return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp);
6456 /* @ignore will accumulate all visited BdrvChild object. The caller is
6457 * responsible for freeing the list afterwards. */
6458 bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
6459 GSList **ignore, Error **errp)
6463 if (bdrv_get_aio_context(bs) == ctx) {
6467 QLIST_FOREACH(c, &bs->parents, next_parent) {
6468 if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) {
6472 QLIST_FOREACH(c, &bs->children, next) {
6473 if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) {
6481 int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
6482 BdrvChild *ignore_child, Error **errp)
6487 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
6488 ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp);
6489 g_slist_free(ignore);
6495 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
6496 bdrv_set_aio_context_ignore(bs, ctx, &ignore);
6497 g_slist_free(ignore);
6502 int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
6505 return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp);
6508 void bdrv_add_aio_context_notifier(BlockDriverState *bs,
6509 void (*attached_aio_context)(AioContext *new_context, void *opaque),
6510 void (*detach_aio_context)(void *opaque), void *opaque)
6512 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1);
6513 *ban = (BdrvAioNotifier){
6514 .attached_aio_context = attached_aio_context,
6515 .detach_aio_context = detach_aio_context,
6519 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list);
6522 void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
6523 void (*attached_aio_context)(AioContext *,
6525 void (*detach_aio_context)(void *),
6528 BdrvAioNotifier *ban, *ban_next;
6530 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
6531 if (ban->attached_aio_context == attached_aio_context &&
6532 ban->detach_aio_context == detach_aio_context &&
6533 ban->opaque == opaque &&
6534 ban->deleted == false)
6536 if (bs->walking_aio_notifiers) {
6537 ban->deleted = true;
6539 bdrv_do_remove_aio_context_notifier(ban);
6548 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
6549 BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
6554 error_setg(errp, "Node is ejected");
6557 if (!bs->drv->bdrv_amend_options) {
6558 error_setg(errp, "Block driver '%s' does not support option amendment",
6559 bs->drv->format_name);
6562 return bs->drv->bdrv_amend_options(bs, opts, status_cb,
6563 cb_opaque, force, errp);
6567 * This function checks whether the given @to_replace is allowed to be
6568 * replaced by a node that always shows the same data as @bs. This is
6569 * used for example to verify whether the mirror job can replace
6570 * @to_replace by the target mirrored from @bs.
6571 * To be replaceable, @bs and @to_replace may either be guaranteed to
6572 * always show the same data (because they are only connected through
6573 * filters), or some driver may allow replacing one of its children
6574 * because it can guarantee that this child's data is not visible at
6575 * all (for example, for dissenting quorum children that have no other
6578 bool bdrv_recurse_can_replace(BlockDriverState *bs,
6579 BlockDriverState *to_replace)
6581 BlockDriverState *filtered;
6583 if (!bs || !bs->drv) {
6587 if (bs == to_replace) {
6591 /* See what the driver can do */
6592 if (bs->drv->bdrv_recurse_can_replace) {
6593 return bs->drv->bdrv_recurse_can_replace(bs, to_replace);
6596 /* For filters without an own implementation, we can recurse on our own */
6597 filtered = bdrv_filter_bs(bs);
6599 return bdrv_recurse_can_replace(filtered, to_replace);
6607 * Check whether the given @node_name can be replaced by a node that
6608 * has the same data as @parent_bs. If so, return @node_name's BDS;
6611 * @node_name must be a (recursive) *child of @parent_bs (or this
6612 * function will return NULL).
6614 * The result (whether the node can be replaced or not) is only valid
6615 * for as long as no graph or permission changes occur.
6617 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
6618 const char *node_name, Error **errp)
6620 BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
6621 AioContext *aio_context;
6623 if (!to_replace_bs) {
6624 error_setg(errp, "Node name '%s' not found", node_name);
6628 aio_context = bdrv_get_aio_context(to_replace_bs);
6629 aio_context_acquire(aio_context);
6631 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
6632 to_replace_bs = NULL;
6636 /* We don't want arbitrary node of the BDS chain to be replaced only the top
6637 * most non filter in order to prevent data corruption.
6638 * Another benefit is that this tests exclude backing files which are
6639 * blocked by the backing blockers.
6641 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) {
6642 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', "
6643 "because it cannot be guaranteed that doing so would not "
6644 "lead to an abrupt change of visible data",
6645 node_name, parent_bs->node_name);
6646 to_replace_bs = NULL;
6651 aio_context_release(aio_context);
6652 return to_replace_bs;
6656 * Iterates through the list of runtime option keys that are said to
6657 * be "strong" for a BDS. An option is called "strong" if it changes
6658 * a BDS's data. For example, the null block driver's "size" and
6659 * "read-zeroes" options are strong, but its "latency-ns" option is
6662 * If a key returned by this function ends with a dot, all options
6663 * starting with that prefix are strong.
6665 static const char *const *strong_options(BlockDriverState *bs,
6666 const char *const *curopt)
6668 static const char *const global_options[] = {
6669 "driver", "filename", NULL
6673 return &global_options[0];
6677 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
6678 curopt = bs->drv->strong_runtime_opts;
6681 return (curopt && *curopt) ? curopt : NULL;
6685 * Copies all strong runtime options from bs->options to the given
6686 * QDict. The set of strong option keys is determined by invoking
6689 * Returns true iff any strong option was present in bs->options (and
6690 * thus copied to the target QDict) with the exception of "filename"
6691 * and "driver". The caller is expected to use this value to decide
6692 * whether the existence of strong options prevents the generation of
6695 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
6697 bool found_any = false;
6698 const char *const *option_name = NULL;
6704 while ((option_name = strong_options(bs, option_name))) {
6705 bool option_given = false;
6707 assert(strlen(*option_name) > 0);
6708 if ((*option_name)[strlen(*option_name) - 1] != '.') {
6709 QObject *entry = qdict_get(bs->options, *option_name);
6714 qdict_put_obj(d, *option_name, qobject_ref(entry));
6715 option_given = true;
6717 const QDictEntry *entry;
6718 for (entry = qdict_first(bs->options); entry;
6719 entry = qdict_next(bs->options, entry))
6721 if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
6722 qdict_put_obj(d, qdict_entry_key(entry),
6723 qobject_ref(qdict_entry_value(entry)));
6724 option_given = true;
6729 /* While "driver" and "filename" need to be included in a JSON filename,
6730 * their existence does not prohibit generation of a plain filename. */
6731 if (!found_any && option_given &&
6732 strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
6738 if (!qdict_haskey(d, "driver")) {
6739 /* Drivers created with bdrv_new_open_driver() may not have a
6740 * @driver option. Add it here. */
6741 qdict_put_str(d, "driver", bs->drv->format_name);
6747 /* Note: This function may return false positives; it may return true
6748 * even if opening the backing file specified by bs's image header
6749 * would result in exactly bs->backing. */
6750 static bool bdrv_backing_overridden(BlockDriverState *bs)
6753 return strcmp(bs->auto_backing_file,
6754 bs->backing->bs->filename);
6756 /* No backing BDS, so if the image header reports any backing
6757 * file, it must have been suppressed */
6758 return bs->auto_backing_file[0] != '\0';
6762 /* Updates the following BDS fields:
6763 * - exact_filename: A filename which may be used for opening a block device
6764 * which (mostly) equals the given BDS (even without any
6765 * other options; so reading and writing must return the same
6766 * results, but caching etc. may be different)
6767 * - full_open_options: Options which, when given when opening a block device
6768 * (without a filename), result in a BDS (mostly)
6769 * equalling the given one
6770 * - filename: If exact_filename is set, it is copied here. Otherwise,
6771 * full_open_options is converted to a JSON object, prefixed with
6772 * "json:" (for use through the JSON pseudo protocol) and put here.
6774 void bdrv_refresh_filename(BlockDriverState *bs)
6776 BlockDriver *drv = bs->drv;
6779 bool backing_overridden;
6780 bool generate_json_filename; /* Whether our default implementation should
6781 fill exact_filename (false) or not (true) */
6787 /* This BDS's file name may depend on any of its children's file names, so
6788 * refresh those first */
6789 QLIST_FOREACH(child, &bs->children, next) {
6790 bdrv_refresh_filename(child->bs);
6794 /* For implicit nodes, just copy everything from the single child */
6795 child = QLIST_FIRST(&bs->children);
6796 assert(QLIST_NEXT(child, next) == NULL);
6798 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
6799 child->bs->exact_filename);
6800 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
6802 qobject_unref(bs->full_open_options);
6803 bs->full_open_options = qobject_ref(child->bs->full_open_options);
6808 backing_overridden = bdrv_backing_overridden(bs);
6810 if (bs->open_flags & BDRV_O_NO_IO) {
6811 /* Without I/O, the backing file does not change anything.
6812 * Therefore, in such a case (primarily qemu-img), we can
6813 * pretend the backing file has not been overridden even if
6814 * it technically has been. */
6815 backing_overridden = false;
6818 /* Gather the options QDict */
6820 generate_json_filename = append_strong_runtime_options(opts, bs);
6821 generate_json_filename |= backing_overridden;
6823 if (drv->bdrv_gather_child_options) {
6824 /* Some block drivers may not want to present all of their children's
6825 * options, or name them differently from BdrvChild.name */
6826 drv->bdrv_gather_child_options(bs, opts, backing_overridden);
6828 QLIST_FOREACH(child, &bs->children, next) {
6829 if (child == bs->backing && !backing_overridden) {
6830 /* We can skip the backing BDS if it has not been overridden */
6834 qdict_put(opts, child->name,
6835 qobject_ref(child->bs->full_open_options));
6838 if (backing_overridden && !bs->backing) {
6839 /* Force no backing file */
6840 qdict_put_null(opts, "backing");
6844 qobject_unref(bs->full_open_options);
6845 bs->full_open_options = opts;
6847 if (drv->bdrv_refresh_filename) {
6848 /* Obsolete information is of no use here, so drop the old file name
6849 * information before refreshing it */
6850 bs->exact_filename[0] = '\0';
6852 drv->bdrv_refresh_filename(bs);
6853 } else if (bs->file) {
6854 /* Try to reconstruct valid information from the underlying file */
6856 bs->exact_filename[0] = '\0';
6859 * We can use the underlying file's filename if:
6860 * - it has a filename,
6861 * - the file is a protocol BDS, and
6862 * - opening that file (as this BDS's format) will automatically create
6863 * the BDS tree we have right now, that is:
6864 * - the user did not significantly change this BDS's behavior with
6865 * some explicit (strong) options
6866 * - no non-file child of this BDS has been overridden by the user
6867 * Both of these conditions are represented by generate_json_filename.
6869 if (bs->file->bs->exact_filename[0] &&
6870 bs->file->bs->drv->bdrv_file_open &&
6871 !generate_json_filename)
6873 strcpy(bs->exact_filename, bs->file->bs->exact_filename);
6877 if (bs->exact_filename[0]) {
6878 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
6880 QString *json = qobject_to_json(QOBJECT(bs->full_open_options));
6881 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s",
6882 qstring_get_str(json)) >= sizeof(bs->filename)) {
6883 /* Give user a hint if we truncated things. */
6884 strcpy(bs->filename + sizeof(bs->filename) - 4, "...");
6886 qobject_unref(json);
6890 char *bdrv_dirname(BlockDriverState *bs, Error **errp)
6892 BlockDriver *drv = bs->drv;
6895 error_setg(errp, "Node '%s' is ejected", bs->node_name);
6899 if (drv->bdrv_dirname) {
6900 return drv->bdrv_dirname(bs, errp);
6904 return bdrv_dirname(bs->file->bs, errp);
6907 bdrv_refresh_filename(bs);
6908 if (bs->exact_filename[0] != '\0') {
6909 return path_combine(bs->exact_filename, "");
6912 error_setg(errp, "Cannot generate a base directory for %s nodes",
6918 * Hot add/remove a BDS's child. So the user can take a child offline when
6919 * it is broken and take a new child online
6921 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
6925 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
6926 error_setg(errp, "The node %s does not support adding a child",
6927 bdrv_get_device_or_node_name(parent_bs));
6931 if (!QLIST_EMPTY(&child_bs->parents)) {
6932 error_setg(errp, "The node %s already has a parent",
6933 child_bs->node_name);
6937 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
6940 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
6944 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
6945 error_setg(errp, "The node %s does not support removing a child",
6946 bdrv_get_device_or_node_name(parent_bs));
6950 QLIST_FOREACH(tmp, &parent_bs->children, next) {
6957 error_setg(errp, "The node %s does not have a child named %s",
6958 bdrv_get_device_or_node_name(parent_bs),
6959 bdrv_get_device_or_node_name(child->bs));
6963 parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
6966 int bdrv_make_empty(BdrvChild *c, Error **errp)
6968 BlockDriver *drv = c->bs->drv;
6971 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED));
6973 if (!drv->bdrv_make_empty) {
6974 error_setg(errp, "%s does not support emptying nodes",
6979 ret = drv->bdrv_make_empty(c->bs);
6981 error_setg_errno(errp, -ret, "Failed to empty %s",
6990 * Return the child that @bs acts as an overlay for, and from which data may be
6991 * copied in COW or COR operations. Usually this is the backing file.
6993 BdrvChild *bdrv_cow_child(BlockDriverState *bs)
6995 if (!bs || !bs->drv) {
6999 if (bs->drv->is_filter) {
7007 assert(bs->backing->role & BDRV_CHILD_COW);
7012 * If @bs acts as a filter for exactly one of its children, return
7015 BdrvChild *bdrv_filter_child(BlockDriverState *bs)
7019 if (!bs || !bs->drv) {
7023 if (!bs->drv->is_filter) {
7027 /* Only one of @backing or @file may be used */
7028 assert(!(bs->backing && bs->file));
7030 c = bs->backing ?: bs->file;
7035 assert(c->role & BDRV_CHILD_FILTERED);
7040 * Return either the result of bdrv_cow_child() or bdrv_filter_child(),
7041 * whichever is non-NULL.
7043 * Return NULL if both are NULL.
7045 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs)
7047 BdrvChild *cow_child = bdrv_cow_child(bs);
7048 BdrvChild *filter_child = bdrv_filter_child(bs);
7050 /* Filter nodes cannot have COW backing files */
7051 assert(!(cow_child && filter_child));
7053 return cow_child ?: filter_child;
7057 * Return the primary child of this node: For filters, that is the
7058 * filtered child. For other nodes, that is usually the child storing
7060 * (A generally more helpful description is that this is (usually) the
7061 * child that has the same filename as @bs.)
7063 * Drivers do not necessarily have a primary child; for example quorum
7066 BdrvChild *bdrv_primary_child(BlockDriverState *bs)
7068 BdrvChild *c, *found = NULL;
7070 QLIST_FOREACH(c, &bs->children, next) {
7071 if (c->role & BDRV_CHILD_PRIMARY) {
7080 static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs,
7081 bool stop_on_explicit_filter)
7089 while (!(stop_on_explicit_filter && !bs->implicit)) {
7090 c = bdrv_filter_child(bs);
7093 * A filter that is embedded in a working block graph must
7094 * have a child. Assert this here so this function does
7095 * not return a filter node that is not expected by the
7098 assert(!bs->drv || !bs->drv->is_filter);
7104 * Note that this treats nodes with bs->drv == NULL as not being
7105 * filters (bs->drv == NULL should be replaced by something else
7107 * The advantage of this behavior is that this function will thus
7108 * always return a non-NULL value (given a non-NULL @bs).
7115 * Return the first BDS that has not been added implicitly or that
7116 * does not have a filtered child down the chain starting from @bs
7117 * (including @bs itself).
7119 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
7121 return bdrv_do_skip_filters(bs, true);
7125 * Return the first BDS that does not have a filtered child down the
7126 * chain starting from @bs (including @bs itself).
7128 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
7130 return bdrv_do_skip_filters(bs, false);
7134 * For a backing chain, return the first non-filter backing image of
7135 * the first non-filter image.
7137 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
7139 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));