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/fuse.h"
30 #include "block/nbd.h"
31 #include "block/qdict.h"
32 #include "qemu/error-report.h"
33 #include "block/module_block.h"
34 #include "qemu/main-loop.h"
35 #include "qemu/module.h"
36 #include "qapi/error.h"
37 #include "qapi/qmp/qdict.h"
38 #include "qapi/qmp/qjson.h"
39 #include "qapi/qmp/qnull.h"
40 #include "qapi/qmp/qstring.h"
41 #include "qapi/qobject-output-visitor.h"
42 #include "qapi/qapi-visit-block-core.h"
43 #include "sysemu/block-backend.h"
44 #include "sysemu/sysemu.h"
45 #include "qemu/notify.h"
46 #include "qemu/option.h"
47 #include "qemu/coroutine.h"
48 #include "block/qapi.h"
49 #include "qemu/timer.h"
50 #include "qemu/cutils.h"
52 #include "block/coroutines.h"
55 #include <sys/ioctl.h>
56 #include <sys/queue.h>
66 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
68 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
69 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
71 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
72 QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
74 static QLIST_HEAD(, BlockDriver) bdrv_drivers =
75 QLIST_HEAD_INITIALIZER(bdrv_drivers);
77 static BlockDriverState *bdrv_open_inherit(const char *filename,
78 const char *reference,
79 QDict *options, int flags,
80 BlockDriverState *parent,
81 const BdrvChildClass *child_class,
82 BdrvChildRole child_role,
85 /* If non-zero, use only whitelisted block drivers */
86 static int use_bdrv_whitelist;
89 static int is_windows_drive_prefix(const char *filename)
91 return (((filename[0] >= 'a' && filename[0] <= 'z') ||
92 (filename[0] >= 'A' && filename[0] <= 'Z')) &&
96 int is_windows_drive(const char *filename)
98 if (is_windows_drive_prefix(filename) &&
101 if (strstart(filename, "\\\\.\\", NULL) ||
102 strstart(filename, "//./", NULL))
108 size_t bdrv_opt_mem_align(BlockDriverState *bs)
110 if (!bs || !bs->drv) {
111 /* page size or 4k (hdd sector size) should be on the safe side */
112 return MAX(4096, qemu_real_host_page_size);
115 return bs->bl.opt_mem_alignment;
118 size_t bdrv_min_mem_align(BlockDriverState *bs)
120 if (!bs || !bs->drv) {
121 /* page size or 4k (hdd sector size) should be on the safe side */
122 return MAX(4096, qemu_real_host_page_size);
125 return bs->bl.min_mem_alignment;
128 /* check if the path starts with "<protocol>:" */
129 int path_has_protocol(const char *path)
134 if (is_windows_drive(path) ||
135 is_windows_drive_prefix(path)) {
138 p = path + strcspn(path, ":/\\");
140 p = path + strcspn(path, ":/");
146 int path_is_absolute(const char *path)
149 /* specific case for names like: "\\.\d:" */
150 if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
153 return (*path == '/' || *path == '\\');
155 return (*path == '/');
159 /* if filename is absolute, just return its duplicate. Otherwise, build a
160 path to it by considering it is relative to base_path. URL are
162 char *path_combine(const char *base_path, const char *filename)
164 const char *protocol_stripped = NULL;
169 if (path_is_absolute(filename)) {
170 return g_strdup(filename);
173 if (path_has_protocol(base_path)) {
174 protocol_stripped = strchr(base_path, ':');
175 if (protocol_stripped) {
179 p = protocol_stripped ?: base_path;
181 p1 = strrchr(base_path, '/');
185 p2 = strrchr(base_path, '\\');
186 if (!p1 || p2 > p1) {
201 result = g_malloc(len + strlen(filename) + 1);
202 memcpy(result, base_path, len);
203 strcpy(result + len, filename);
209 * Helper function for bdrv_parse_filename() implementations to remove optional
210 * protocol prefixes (especially "file:") from a filename and for putting the
211 * stripped filename into the options QDict if there is such a prefix.
213 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
216 if (strstart(filename, prefix, &filename)) {
217 /* Stripping the explicit protocol prefix may result in a protocol
218 * prefix being (wrongly) detected (if the filename contains a colon) */
219 if (path_has_protocol(filename)) {
220 QString *fat_filename;
222 /* This means there is some colon before the first slash; therefore,
223 * this cannot be an absolute path */
224 assert(!path_is_absolute(filename));
226 /* And we can thus fix the protocol detection issue by prefixing it
228 fat_filename = qstring_from_str("./");
229 qstring_append(fat_filename, filename);
231 assert(!path_has_protocol(qstring_get_str(fat_filename)));
233 qdict_put(options, "filename", fat_filename);
235 /* If no protocol prefix was detected, we can use the shortened
237 qdict_put_str(options, "filename", filename);
243 /* Returns whether the image file is opened as read-only. Note that this can
244 * return false and writing to the image file is still not possible because the
245 * image is inactivated. */
246 bool bdrv_is_read_only(BlockDriverState *bs)
248 return bs->read_only;
251 int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
252 bool ignore_allow_rdw, Error **errp)
254 /* Do not set read_only if copy_on_read is enabled */
255 if (bs->copy_on_read && read_only) {
256 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
257 bdrv_get_device_or_node_name(bs));
261 /* Do not clear read_only if it is prohibited */
262 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
265 error_setg(errp, "Node '%s' is read only",
266 bdrv_get_device_or_node_name(bs));
274 * Called by a driver that can only provide a read-only image.
276 * Returns 0 if the node is already read-only or it could switch the node to
277 * read-only because BDRV_O_AUTO_RDONLY is set.
279 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
280 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
281 * is not NULL, it is used as the error message for the Error object.
283 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
288 if (!(bs->open_flags & BDRV_O_RDWR)) {
291 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
295 ret = bdrv_can_set_read_only(bs, true, false, NULL);
300 bs->read_only = true;
301 bs->open_flags &= ~BDRV_O_RDWR;
306 error_setg(errp, "%s", errmsg ?: "Image is read-only");
311 * If @backing is empty, this function returns NULL without setting
312 * @errp. In all other cases, NULL will only be returned with @errp
315 * Therefore, a return value of NULL without @errp set means that
316 * there is no backing file; if @errp is set, there is one but its
317 * absolute filename cannot be generated.
319 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
323 if (backing[0] == '\0') {
325 } else if (path_has_protocol(backing) || path_is_absolute(backing)) {
326 return g_strdup(backing);
327 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
328 error_setg(errp, "Cannot use relative backing file names for '%s'",
332 return path_combine(backed, backing);
337 * If @filename is empty or NULL, this function returns NULL without
338 * setting @errp. In all other cases, NULL will only be returned with
341 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
342 const char *filename, Error **errp)
344 char *dir, *full_name;
346 if (!filename || filename[0] == '\0') {
348 } else if (path_has_protocol(filename) || path_is_absolute(filename)) {
349 return g_strdup(filename);
352 dir = bdrv_dirname(relative_to, errp);
357 full_name = g_strconcat(dir, filename, NULL);
362 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
364 return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
367 void bdrv_register(BlockDriver *bdrv)
369 assert(bdrv->format_name);
370 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
373 BlockDriverState *bdrv_new(void)
375 BlockDriverState *bs;
378 bs = g_new0(BlockDriverState, 1);
379 QLIST_INIT(&bs->dirty_bitmaps);
380 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
381 QLIST_INIT(&bs->op_blockers[i]);
383 notifier_with_return_list_init(&bs->before_write_notifiers);
384 qemu_co_mutex_init(&bs->reqs_lock);
385 qemu_mutex_init(&bs->dirty_bitmap_mutex);
387 bs->aio_context = qemu_get_aio_context();
389 qemu_co_queue_init(&bs->flush_queue);
391 for (i = 0; i < bdrv_drain_all_count; i++) {
392 bdrv_drained_begin(bs);
395 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
400 static BlockDriver *bdrv_do_find_format(const char *format_name)
404 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
405 if (!strcmp(drv1->format_name, format_name)) {
413 BlockDriver *bdrv_find_format(const char *format_name)
418 drv1 = bdrv_do_find_format(format_name);
423 /* The driver isn't registered, maybe we need to load a module */
424 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
425 if (!strcmp(block_driver_modules[i].format_name, format_name)) {
426 block_module_load_one(block_driver_modules[i].library_name);
431 return bdrv_do_find_format(format_name);
434 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
436 static const char *whitelist_rw[] = {
437 CONFIG_BDRV_RW_WHITELIST
440 static const char *whitelist_ro[] = {
441 CONFIG_BDRV_RO_WHITELIST
446 if (!whitelist_rw[0] && !whitelist_ro[0]) {
447 return 1; /* no whitelist, anything goes */
450 for (p = whitelist_rw; *p; p++) {
451 if (!strcmp(format_name, *p)) {
456 for (p = whitelist_ro; *p; p++) {
457 if (!strcmp(format_name, *p)) {
465 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
467 return bdrv_format_is_whitelisted(drv->format_name, read_only);
470 bool bdrv_uses_whitelist(void)
472 return use_bdrv_whitelist;
475 typedef struct CreateCo {
483 static void coroutine_fn bdrv_create_co_entry(void *opaque)
485 Error *local_err = NULL;
488 CreateCo *cco = opaque;
491 ret = cco->drv->bdrv_co_create_opts(cco->drv,
492 cco->filename, cco->opts, &local_err);
493 error_propagate(&cco->err, local_err);
497 int bdrv_create(BlockDriver *drv, const char* filename,
498 QemuOpts *opts, Error **errp)
505 .filename = g_strdup(filename),
511 if (!drv->bdrv_co_create_opts) {
512 error_setg(errp, "Driver '%s' does not support image creation", drv->format_name);
517 if (qemu_in_coroutine()) {
518 /* Fast-path if already in coroutine context */
519 bdrv_create_co_entry(&cco);
521 co = qemu_coroutine_create(bdrv_create_co_entry, &cco);
522 qemu_coroutine_enter(co);
523 while (cco.ret == NOT_DONE) {
524 aio_poll(qemu_get_aio_context(), true);
531 error_propagate(errp, cco.err);
533 error_setg_errno(errp, -ret, "Could not create image");
538 g_free(cco.filename);
543 * Helper function for bdrv_create_file_fallback(): Resize @blk to at
544 * least the given @minimum_size.
546 * On success, return @blk's actual length.
547 * Otherwise, return -errno.
549 static int64_t create_file_fallback_truncate(BlockBackend *blk,
550 int64_t minimum_size, Error **errp)
552 Error *local_err = NULL;
556 ret = blk_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0,
558 if (ret < 0 && ret != -ENOTSUP) {
559 error_propagate(errp, local_err);
563 size = blk_getlength(blk);
565 error_free(local_err);
566 error_setg_errno(errp, -size,
567 "Failed to inquire the new image file's length");
571 if (size < minimum_size) {
572 /* Need to grow the image, but we failed to do that */
573 error_propagate(errp, local_err);
577 error_free(local_err);
584 * Helper function for bdrv_create_file_fallback(): Zero the first
585 * sector to remove any potentially pre-existing image header.
587 static int create_file_fallback_zero_first_sector(BlockBackend *blk,
588 int64_t current_size,
591 int64_t bytes_to_clear;
594 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
595 if (bytes_to_clear) {
596 ret = blk_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
598 error_setg_errno(errp, -ret,
599 "Failed to clear the new image's first sector");
608 * Simple implementation of bdrv_co_create_opts for protocol drivers
609 * which only support creation via opening a file
610 * (usually existing raw storage device)
612 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
613 const char *filename,
621 PreallocMode prealloc;
622 Error *local_err = NULL;
625 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
626 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
627 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
628 PREALLOC_MODE_OFF, &local_err);
631 error_propagate(errp, local_err);
635 if (prealloc != PREALLOC_MODE_OFF) {
636 error_setg(errp, "Unsupported preallocation mode '%s'",
637 PreallocMode_str(prealloc));
641 options = qdict_new();
642 qdict_put_str(options, "driver", drv->format_name);
644 blk = blk_new_open(filename, NULL, options,
645 BDRV_O_RDWR | BDRV_O_RESIZE, errp);
647 error_prepend(errp, "Protocol driver '%s' does not support image "
648 "creation, and opening the image failed: ",
653 size = create_file_fallback_truncate(blk, size, errp);
659 ret = create_file_fallback_zero_first_sector(blk, size, errp);
670 int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
674 drv = bdrv_find_protocol(filename, true, errp);
679 return bdrv_create(drv, filename, opts, errp);
682 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
684 Error *local_err = NULL;
690 error_setg(errp, "Block node '%s' is not opened", bs->filename);
694 if (!bs->drv->bdrv_co_delete_file) {
695 error_setg(errp, "Driver '%s' does not support image deletion",
696 bs->drv->format_name);
700 ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
702 error_propagate(errp, local_err);
709 * Try to get @bs's logical and physical block size.
710 * On success, store them in @bsz struct and return 0.
711 * On failure return -errno.
712 * @bs must not be empty.
714 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
716 BlockDriver *drv = bs->drv;
717 BlockDriverState *filtered = bdrv_filter_bs(bs);
719 if (drv && drv->bdrv_probe_blocksizes) {
720 return drv->bdrv_probe_blocksizes(bs, bsz);
721 } else if (filtered) {
722 return bdrv_probe_blocksizes(filtered, bsz);
729 * Try to get @bs's geometry (cyls, heads, sectors).
730 * On success, store them in @geo struct and return 0.
731 * On failure return -errno.
732 * @bs must not be empty.
734 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
736 BlockDriver *drv = bs->drv;
737 BlockDriverState *filtered = bdrv_filter_bs(bs);
739 if (drv && drv->bdrv_probe_geometry) {
740 return drv->bdrv_probe_geometry(bs, geo);
741 } else if (filtered) {
742 return bdrv_probe_geometry(filtered, geo);
749 * Create a uniquely-named empty temporary file.
750 * Return 0 upon success, otherwise a negative errno value.
752 int get_tmp_filename(char *filename, int size)
755 char temp_dir[MAX_PATH];
756 /* GetTempFileName requires that its output buffer (4th param)
757 have length MAX_PATH or greater. */
758 assert(size >= MAX_PATH);
759 return (GetTempPath(MAX_PATH, temp_dir)
760 && GetTempFileName(temp_dir, "qem", 0, filename)
761 ? 0 : -GetLastError());
765 tmpdir = getenv("TMPDIR");
769 if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) {
772 fd = mkstemp(filename);
776 if (close(fd) != 0) {
785 * Detect host devices. By convention, /dev/cdrom[N] is always
786 * recognized as a host CDROM.
788 static BlockDriver *find_hdev_driver(const char *filename)
790 int score_max = 0, score;
791 BlockDriver *drv = NULL, *d;
793 QLIST_FOREACH(d, &bdrv_drivers, list) {
794 if (d->bdrv_probe_device) {
795 score = d->bdrv_probe_device(filename);
796 if (score > score_max) {
806 static BlockDriver *bdrv_do_find_protocol(const char *protocol)
810 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
811 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
819 BlockDriver *bdrv_find_protocol(const char *filename,
820 bool allow_protocol_prefix,
829 /* TODO Drivers without bdrv_file_open must be specified explicitly */
832 * XXX(hch): we really should not let host device detection
833 * override an explicit protocol specification, but moving this
834 * later breaks access to device names with colons in them.
835 * Thanks to the brain-dead persistent naming schemes on udev-
836 * based Linux systems those actually are quite common.
838 drv1 = find_hdev_driver(filename);
843 if (!path_has_protocol(filename) || !allow_protocol_prefix) {
847 p = strchr(filename, ':');
850 if (len > sizeof(protocol) - 1)
851 len = sizeof(protocol) - 1;
852 memcpy(protocol, filename, len);
853 protocol[len] = '\0';
855 drv1 = bdrv_do_find_protocol(protocol);
860 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
861 if (block_driver_modules[i].protocol_name &&
862 !strcmp(block_driver_modules[i].protocol_name, protocol)) {
863 block_module_load_one(block_driver_modules[i].library_name);
868 drv1 = bdrv_do_find_protocol(protocol);
870 error_setg(errp, "Unknown protocol '%s'", protocol);
876 * Guess image format by probing its contents.
877 * This is not a good idea when your image is raw (CVE-2008-2004), but
878 * we do it anyway for backward compatibility.
880 * @buf contains the image's first @buf_size bytes.
881 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
882 * but can be smaller if the image file is smaller)
883 * @filename is its filename.
885 * For all block drivers, call the bdrv_probe() method to get its
887 * Return the first block driver with the highest probing score.
889 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
890 const char *filename)
892 int score_max = 0, score;
893 BlockDriver *drv = NULL, *d;
895 QLIST_FOREACH(d, &bdrv_drivers, list) {
897 score = d->bdrv_probe(buf, buf_size, filename);
898 if (score > score_max) {
908 static int find_image_format(BlockBackend *file, const char *filename,
909 BlockDriver **pdrv, Error **errp)
912 uint8_t buf[BLOCK_PROBE_BUF_SIZE];
915 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */
916 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
921 ret = blk_pread(file, 0, buf, sizeof(buf));
923 error_setg_errno(errp, -ret, "Could not read image for determining its "
929 drv = bdrv_probe_all(buf, ret, filename);
931 error_setg(errp, "Could not determine image format: No compatible "
940 * Set the current 'total_sectors' value
941 * Return 0 on success, -errno on error.
943 int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
945 BlockDriver *drv = bs->drv;
951 /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
955 /* query actual device if possible, otherwise just trust the hint */
956 if (drv->bdrv_getlength) {
957 int64_t length = drv->bdrv_getlength(bs);
961 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
964 bs->total_sectors = hint;
966 if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) {
974 * Combines a QDict of new block driver @options with any missing options taken
975 * from @old_options, so that leaving out an option defaults to its old value.
977 static void bdrv_join_options(BlockDriverState *bs, QDict *options,
980 if (bs->drv && bs->drv->bdrv_join_options) {
981 bs->drv->bdrv_join_options(options, old_options);
983 qdict_join(options, old_options, false);
987 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
991 Error *local_err = NULL;
992 char *value = qemu_opt_get_del(opts, "detect-zeroes");
993 BlockdevDetectZeroesOptions detect_zeroes =
994 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
995 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
998 error_propagate(errp, local_err);
999 return detect_zeroes;
1002 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
1003 !(open_flags & BDRV_O_UNMAP))
1005 error_setg(errp, "setting detect-zeroes to unmap is not allowed "
1006 "without setting discard operation to unmap");
1009 return detect_zeroes;
1013 * Set open flags for aio engine
1015 * Return 0 on success, -1 if the engine specified is invalid
1017 int bdrv_parse_aio(const char *mode, int *flags)
1019 if (!strcmp(mode, "threads")) {
1020 /* do nothing, default */
1021 } else if (!strcmp(mode, "native")) {
1022 *flags |= BDRV_O_NATIVE_AIO;
1023 #ifdef CONFIG_LINUX_IO_URING
1024 } else if (!strcmp(mode, "io_uring")) {
1025 *flags |= BDRV_O_IO_URING;
1035 * Set open flags for a given discard mode
1037 * Return 0 on success, -1 if the discard mode was invalid.
1039 int bdrv_parse_discard_flags(const char *mode, int *flags)
1041 *flags &= ~BDRV_O_UNMAP;
1043 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
1045 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
1046 *flags |= BDRV_O_UNMAP;
1055 * Set open flags for a given cache mode
1057 * Return 0 on success, -1 if the cache mode was invalid.
1059 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
1061 *flags &= ~BDRV_O_CACHE_MASK;
1063 if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
1064 *writethrough = false;
1065 *flags |= BDRV_O_NOCACHE;
1066 } else if (!strcmp(mode, "directsync")) {
1067 *writethrough = true;
1068 *flags |= BDRV_O_NOCACHE;
1069 } else if (!strcmp(mode, "writeback")) {
1070 *writethrough = false;
1071 } else if (!strcmp(mode, "unsafe")) {
1072 *writethrough = false;
1073 *flags |= BDRV_O_NO_FLUSH;
1074 } else if (!strcmp(mode, "writethrough")) {
1075 *writethrough = true;
1083 static char *bdrv_child_get_parent_desc(BdrvChild *c)
1085 BlockDriverState *parent = c->opaque;
1086 return g_strdup(bdrv_get_device_or_node_name(parent));
1089 static void bdrv_child_cb_drained_begin(BdrvChild *child)
1091 BlockDriverState *bs = child->opaque;
1092 bdrv_do_drained_begin_quiesce(bs, NULL, false);
1095 static bool bdrv_child_cb_drained_poll(BdrvChild *child)
1097 BlockDriverState *bs = child->opaque;
1098 return bdrv_drain_poll(bs, false, NULL, false);
1101 static void bdrv_child_cb_drained_end(BdrvChild *child,
1102 int *drained_end_counter)
1104 BlockDriverState *bs = child->opaque;
1105 bdrv_drained_end_no_poll(bs, drained_end_counter);
1108 static int bdrv_child_cb_inactivate(BdrvChild *child)
1110 BlockDriverState *bs = child->opaque;
1111 assert(bs->open_flags & BDRV_O_INACTIVE);
1115 static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
1116 GSList **ignore, Error **errp)
1118 BlockDriverState *bs = child->opaque;
1119 return bdrv_can_set_aio_context(bs, ctx, ignore, errp);
1122 static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx,
1125 BlockDriverState *bs = child->opaque;
1126 return bdrv_set_aio_context_ignore(bs, ctx, ignore);
1130 * Returns the options and flags that a temporary snapshot should get, based on
1131 * the originally requested flags (the originally requested image will have
1132 * flags like a backing file)
1134 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
1135 int parent_flags, QDict *parent_options)
1137 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
1139 /* For temporary files, unconditional cache=unsafe is fine */
1140 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
1141 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
1143 /* Copy the read-only and discard options from the parent */
1144 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1145 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
1147 /* aio=native doesn't work for cache.direct=off, so disable it for the
1148 * temporary snapshot */
1149 *child_flags &= ~BDRV_O_NATIVE_AIO;
1152 static void bdrv_backing_attach(BdrvChild *c)
1154 BlockDriverState *parent = c->opaque;
1155 BlockDriverState *backing_hd = c->bs;
1157 assert(!parent->backing_blocker);
1158 error_setg(&parent->backing_blocker,
1159 "node is used as backing hd of '%s'",
1160 bdrv_get_device_or_node_name(parent));
1162 bdrv_refresh_filename(backing_hd);
1164 parent->open_flags &= ~BDRV_O_NO_BACKING;
1166 bdrv_op_block_all(backing_hd, parent->backing_blocker);
1167 /* Otherwise we won't be able to commit or stream */
1168 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
1169 parent->backing_blocker);
1170 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
1171 parent->backing_blocker);
1173 * We do backup in 3 ways:
1175 * The target bs is new opened, and the source is top BDS
1176 * 2. blockdev backup
1177 * Both the source and the target are top BDSes.
1178 * 3. internal backup(used for block replication)
1179 * Both the source and the target are backing file
1181 * In case 1 and 2, neither the source nor the target is the backing file.
1182 * In case 3, we will block the top BDS, so there is only one block job
1183 * for the top BDS and its backing chain.
1185 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
1186 parent->backing_blocker);
1187 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
1188 parent->backing_blocker);
1191 static void bdrv_backing_detach(BdrvChild *c)
1193 BlockDriverState *parent = c->opaque;
1195 assert(parent->backing_blocker);
1196 bdrv_op_unblock_all(c->bs, parent->backing_blocker);
1197 error_free(parent->backing_blocker);
1198 parent->backing_blocker = NULL;
1201 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
1202 const char *filename, Error **errp)
1204 BlockDriverState *parent = c->opaque;
1205 bool read_only = bdrv_is_read_only(parent);
1209 ret = bdrv_reopen_set_read_only(parent, false, errp);
1215 ret = bdrv_change_backing_file(parent, filename,
1216 base->drv ? base->drv->format_name : "",
1219 error_setg_errno(errp, -ret, "Could not update backing file link");
1223 bdrv_reopen_set_read_only(parent, true, NULL);
1230 * Returns the options and flags that a generic child of a BDS should
1231 * get, based on the given options and flags for the parent BDS.
1233 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
1234 int *child_flags, QDict *child_options,
1235 int parent_flags, QDict *parent_options)
1237 int flags = parent_flags;
1240 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL.
1241 * Generally, the question to answer is: Should this child be
1242 * format-probed by default?
1246 * Pure and non-filtered data children of non-format nodes should
1247 * be probed by default (even when the node itself has BDRV_O_PROTOCOL
1248 * set). This only affects a very limited set of drivers (namely
1249 * quorum and blkverify when this comment was written).
1250 * Force-clear BDRV_O_PROTOCOL then.
1252 if (!parent_is_format &&
1253 (role & BDRV_CHILD_DATA) &&
1254 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED)))
1256 flags &= ~BDRV_O_PROTOCOL;
1260 * All children of format nodes (except for COW children) and all
1261 * metadata children in general should never be format-probed.
1262 * Force-set BDRV_O_PROTOCOL then.
1264 if ((parent_is_format && !(role & BDRV_CHILD_COW)) ||
1265 (role & BDRV_CHILD_METADATA))
1267 flags |= BDRV_O_PROTOCOL;
1271 * If the cache mode isn't explicitly set, inherit direct and no-flush from
1274 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
1275 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
1276 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
1278 if (role & BDRV_CHILD_COW) {
1279 /* backing files are opened read-only by default */
1280 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
1281 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
1283 /* Inherit the read-only option from the parent if it's not set */
1284 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1285 qdict_copy_default(child_options, parent_options,
1286 BDRV_OPT_AUTO_READ_ONLY);
1290 * bdrv_co_pdiscard() respects unmap policy for the parent, so we
1291 * can default to enable it on lower layers regardless of the
1294 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
1296 /* Clear flags that only apply to the top layer */
1297 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
1299 if (role & BDRV_CHILD_METADATA) {
1300 flags &= ~BDRV_O_NO_IO;
1302 if (role & BDRV_CHILD_COW) {
1303 flags &= ~BDRV_O_TEMPORARY;
1306 *child_flags = flags;
1309 static void bdrv_child_cb_attach(BdrvChild *child)
1311 BlockDriverState *bs = child->opaque;
1313 if (child->role & BDRV_CHILD_COW) {
1314 bdrv_backing_attach(child);
1317 bdrv_apply_subtree_drain(child, bs);
1320 static void bdrv_child_cb_detach(BdrvChild *child)
1322 BlockDriverState *bs = child->opaque;
1324 if (child->role & BDRV_CHILD_COW) {
1325 bdrv_backing_detach(child);
1328 bdrv_unapply_subtree_drain(child, bs);
1331 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
1332 const char *filename, Error **errp)
1334 if (c->role & BDRV_CHILD_COW) {
1335 return bdrv_backing_update_filename(c, base, filename, errp);
1340 const BdrvChildClass child_of_bds = {
1341 .parent_is_bds = true,
1342 .get_parent_desc = bdrv_child_get_parent_desc,
1343 .inherit_options = bdrv_inherited_options,
1344 .drained_begin = bdrv_child_cb_drained_begin,
1345 .drained_poll = bdrv_child_cb_drained_poll,
1346 .drained_end = bdrv_child_cb_drained_end,
1347 .attach = bdrv_child_cb_attach,
1348 .detach = bdrv_child_cb_detach,
1349 .inactivate = bdrv_child_cb_inactivate,
1350 .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
1351 .set_aio_ctx = bdrv_child_cb_set_aio_ctx,
1352 .update_filename = bdrv_child_cb_update_filename,
1355 static int bdrv_open_flags(BlockDriverState *bs, int flags)
1357 int open_flags = flags;
1360 * Clear flags that are internal to the block layer before opening the
1363 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
1368 static void update_flags_from_options(int *flags, QemuOpts *opts)
1370 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
1372 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
1373 *flags |= BDRV_O_NO_FLUSH;
1376 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
1377 *flags |= BDRV_O_NOCACHE;
1380 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
1381 *flags |= BDRV_O_RDWR;
1384 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
1385 *flags |= BDRV_O_AUTO_RDONLY;
1389 static void update_options_from_flags(QDict *options, int flags)
1391 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
1392 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
1394 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
1395 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
1396 flags & BDRV_O_NO_FLUSH);
1398 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
1399 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
1401 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
1402 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
1403 flags & BDRV_O_AUTO_RDONLY);
1407 static void bdrv_assign_node_name(BlockDriverState *bs,
1408 const char *node_name,
1411 char *gen_node_name = NULL;
1414 node_name = gen_node_name = id_generate(ID_BLOCK);
1415 } else if (!id_wellformed(node_name)) {
1417 * Check for empty string or invalid characters, but not if it is
1418 * generated (generated names use characters not available to the user)
1420 error_setg(errp, "Invalid node name");
1424 /* takes care of avoiding namespaces collisions */
1425 if (blk_by_name(node_name)) {
1426 error_setg(errp, "node-name=%s is conflicting with a device id",
1431 /* takes care of avoiding duplicates node names */
1432 if (bdrv_find_node(node_name)) {
1433 error_setg(errp, "Duplicate node name");
1437 /* Make sure that the node name isn't truncated */
1438 if (strlen(node_name) >= sizeof(bs->node_name)) {
1439 error_setg(errp, "Node name too long");
1443 /* copy node name into the bs and insert it into the graph list */
1444 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
1445 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
1447 g_free(gen_node_name);
1450 static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv,
1451 const char *node_name, QDict *options,
1452 int open_flags, Error **errp)
1454 Error *local_err = NULL;
1457 bdrv_assign_node_name(bs, node_name, &local_err);
1459 error_propagate(errp, local_err);
1464 bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
1465 bs->opaque = g_malloc0(drv->instance_size);
1467 if (drv->bdrv_file_open) {
1468 assert(!drv->bdrv_needs_filename || bs->filename[0]);
1469 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
1470 } else if (drv->bdrv_open) {
1471 ret = drv->bdrv_open(bs, options, open_flags, &local_err);
1478 error_propagate(errp, local_err);
1479 } else if (bs->filename[0]) {
1480 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
1482 error_setg_errno(errp, -ret, "Could not open image");
1487 ret = refresh_total_sectors(bs, bs->total_sectors);
1489 error_setg_errno(errp, -ret, "Could not refresh total sector count");
1493 bdrv_refresh_limits(bs, &local_err);
1495 error_propagate(errp, local_err);
1499 assert(bdrv_opt_mem_align(bs) != 0);
1500 assert(bdrv_min_mem_align(bs) != 0);
1501 assert(is_power_of_2(bs->bl.request_alignment));
1503 for (i = 0; i < bs->quiesce_counter; i++) {
1504 if (drv->bdrv_co_drain_begin) {
1505 drv->bdrv_co_drain_begin(bs);
1512 if (bs->file != NULL) {
1513 bdrv_unref_child(bs, bs->file);
1521 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
1522 int flags, Error **errp)
1524 BlockDriverState *bs;
1528 bs->open_flags = flags;
1529 bs->explicit_options = qdict_new();
1530 bs->options = qdict_new();
1533 update_options_from_flags(bs->options, flags);
1535 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
1537 qobject_unref(bs->explicit_options);
1538 bs->explicit_options = NULL;
1539 qobject_unref(bs->options);
1548 QemuOptsList bdrv_runtime_opts = {
1549 .name = "bdrv_common",
1550 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
1553 .name = "node-name",
1554 .type = QEMU_OPT_STRING,
1555 .help = "Node name of the block device node",
1559 .type = QEMU_OPT_STRING,
1560 .help = "Block driver to use for the node",
1563 .name = BDRV_OPT_CACHE_DIRECT,
1564 .type = QEMU_OPT_BOOL,
1565 .help = "Bypass software writeback cache on the host",
1568 .name = BDRV_OPT_CACHE_NO_FLUSH,
1569 .type = QEMU_OPT_BOOL,
1570 .help = "Ignore flush requests",
1573 .name = BDRV_OPT_READ_ONLY,
1574 .type = QEMU_OPT_BOOL,
1575 .help = "Node is opened in read-only mode",
1578 .name = BDRV_OPT_AUTO_READ_ONLY,
1579 .type = QEMU_OPT_BOOL,
1580 .help = "Node can become read-only if opening read-write fails",
1583 .name = "detect-zeroes",
1584 .type = QEMU_OPT_STRING,
1585 .help = "try to optimize zero writes (off, on, unmap)",
1588 .name = BDRV_OPT_DISCARD,
1589 .type = QEMU_OPT_STRING,
1590 .help = "discard operation (ignore/off, unmap/on)",
1593 .name = BDRV_OPT_FORCE_SHARE,
1594 .type = QEMU_OPT_BOOL,
1595 .help = "always accept other writers (default: off)",
1597 { /* end of list */ }
1601 QemuOptsList bdrv_create_opts_simple = {
1602 .name = "simple-create-opts",
1603 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head),
1606 .name = BLOCK_OPT_SIZE,
1607 .type = QEMU_OPT_SIZE,
1608 .help = "Virtual disk size"
1611 .name = BLOCK_OPT_PREALLOC,
1612 .type = QEMU_OPT_STRING,
1613 .help = "Preallocation mode (allowed values: off)"
1615 { /* end of list */ }
1620 * Common part for opening disk images and files
1622 * Removes all processed options from *options.
1624 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
1625 QDict *options, Error **errp)
1627 int ret, open_flags;
1628 const char *filename;
1629 const char *driver_name = NULL;
1630 const char *node_name = NULL;
1631 const char *discard;
1634 Error *local_err = NULL;
1636 assert(bs->file == NULL);
1637 assert(options != NULL && bs->options != options);
1639 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
1640 if (!qemu_opts_absorb_qdict(opts, options, errp)) {
1645 update_flags_from_options(&bs->open_flags, opts);
1647 driver_name = qemu_opt_get(opts, "driver");
1648 drv = bdrv_find_format(driver_name);
1649 assert(drv != NULL);
1651 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
1653 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
1655 BDRV_OPT_FORCE_SHARE
1656 "=on can only be used with read-only images");
1662 bdrv_refresh_filename(blk_bs(file));
1663 filename = blk_bs(file)->filename;
1666 * Caution: while qdict_get_try_str() is fine, getting
1667 * non-string types would require more care. When @options
1668 * come from -blockdev or blockdev_add, its members are typed
1669 * according to the QAPI schema, but when they come from
1670 * -drive, they're all QString.
1672 filename = qdict_get_try_str(options, "filename");
1675 if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
1676 error_setg(errp, "The '%s' block driver requires a file name",
1682 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
1685 bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
1687 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
1688 if (!bs->read_only && bdrv_is_whitelisted(drv, true)) {
1689 ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
1695 !bs->read_only && bdrv_is_whitelisted(drv, true)
1696 ? "Driver '%s' can only be used for read-only devices"
1697 : "Driver '%s' is not whitelisted",
1703 /* bdrv_new() and bdrv_close() make it so */
1704 assert(qatomic_read(&bs->copy_on_read) == 0);
1706 if (bs->open_flags & BDRV_O_COPY_ON_READ) {
1707 if (!bs->read_only) {
1708 bdrv_enable_copy_on_read(bs);
1710 error_setg(errp, "Can't use copy-on-read on read-only device");
1716 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
1717 if (discard != NULL) {
1718 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
1719 error_setg(errp, "Invalid discard option");
1726 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
1728 error_propagate(errp, local_err);
1733 if (filename != NULL) {
1734 pstrcpy(bs->filename, sizeof(bs->filename), filename);
1736 bs->filename[0] = '\0';
1738 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
1740 /* Open the image, either directly or using a protocol */
1741 open_flags = bdrv_open_flags(bs, bs->open_flags);
1742 node_name = qemu_opt_get(opts, "node-name");
1744 assert(!drv->bdrv_file_open || file == NULL);
1745 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
1750 qemu_opts_del(opts);
1754 qemu_opts_del(opts);
1758 static QDict *parse_json_filename(const char *filename, Error **errp)
1760 QObject *options_obj;
1764 ret = strstart(filename, "json:", &filename);
1767 options_obj = qobject_from_json(filename, errp);
1769 error_prepend(errp, "Could not parse the JSON options: ");
1773 options = qobject_to(QDict, options_obj);
1775 qobject_unref(options_obj);
1776 error_setg(errp, "Invalid JSON object given");
1780 qdict_flatten(options);
1785 static void parse_json_protocol(QDict *options, const char **pfilename,
1788 QDict *json_options;
1789 Error *local_err = NULL;
1791 /* Parse json: pseudo-protocol */
1792 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
1796 json_options = parse_json_filename(*pfilename, &local_err);
1798 error_propagate(errp, local_err);
1802 /* Options given in the filename have lower priority than options
1803 * specified directly */
1804 qdict_join(options, json_options, false);
1805 qobject_unref(json_options);
1810 * Fills in default options for opening images and converts the legacy
1811 * filename/flags pair to option QDict entries.
1812 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
1813 * block driver has been specified explicitly.
1815 static int bdrv_fill_options(QDict **options, const char *filename,
1816 int *flags, Error **errp)
1818 const char *drvname;
1819 bool protocol = *flags & BDRV_O_PROTOCOL;
1820 bool parse_filename = false;
1821 BlockDriver *drv = NULL;
1822 Error *local_err = NULL;
1825 * Caution: while qdict_get_try_str() is fine, getting non-string
1826 * types would require more care. When @options come from
1827 * -blockdev or blockdev_add, its members are typed according to
1828 * the QAPI schema, but when they come from -drive, they're all
1831 drvname = qdict_get_try_str(*options, "driver");
1833 drv = bdrv_find_format(drvname);
1835 error_setg(errp, "Unknown driver '%s'", drvname);
1838 /* If the user has explicitly specified the driver, this choice should
1839 * override the BDRV_O_PROTOCOL flag */
1840 protocol = drv->bdrv_file_open;
1844 *flags |= BDRV_O_PROTOCOL;
1846 *flags &= ~BDRV_O_PROTOCOL;
1849 /* Translate cache options from flags into options */
1850 update_options_from_flags(*options, *flags);
1852 /* Fetch the file name from the options QDict if necessary */
1853 if (protocol && filename) {
1854 if (!qdict_haskey(*options, "filename")) {
1855 qdict_put_str(*options, "filename", filename);
1856 parse_filename = true;
1858 error_setg(errp, "Can't specify 'file' and 'filename' options at "
1864 /* Find the right block driver */
1865 /* See cautionary note on accessing @options above */
1866 filename = qdict_get_try_str(*options, "filename");
1868 if (!drvname && protocol) {
1870 drv = bdrv_find_protocol(filename, parse_filename, errp);
1875 drvname = drv->format_name;
1876 qdict_put_str(*options, "driver", drvname);
1878 error_setg(errp, "Must specify either driver or file");
1883 assert(drv || !protocol);
1885 /* Driver-specific filename parsing */
1886 if (drv && drv->bdrv_parse_filename && parse_filename) {
1887 drv->bdrv_parse_filename(filename, *options, &local_err);
1889 error_propagate(errp, local_err);
1893 if (!drv->bdrv_needs_filename) {
1894 qdict_del(*options, "filename");
1901 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
1902 uint64_t perm, uint64_t shared,
1903 GSList *ignore_children,
1904 bool *tighten_restrictions, Error **errp);
1905 static void bdrv_child_abort_perm_update(BdrvChild *c);
1906 static void bdrv_child_set_perm(BdrvChild *c);
1908 typedef struct BlockReopenQueueEntry {
1911 BDRVReopenState state;
1912 QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
1913 } BlockReopenQueueEntry;
1916 * Return the flags that @bs will have after the reopens in @q have
1917 * successfully completed. If @q is NULL (or @bs is not contained in @q),
1918 * return the current flags.
1920 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
1922 BlockReopenQueueEntry *entry;
1925 QTAILQ_FOREACH(entry, q, entry) {
1926 if (entry->state.bs == bs) {
1927 return entry->state.flags;
1932 return bs->open_flags;
1935 /* Returns whether the image file can be written to after the reopen queue @q
1936 * has been successfully applied, or right now if @q is NULL. */
1937 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
1938 BlockReopenQueue *q)
1940 int flags = bdrv_reopen_get_flags(q, bs);
1942 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
1946 * Return whether the BDS can be written to. This is not necessarily
1947 * the same as !bdrv_is_read_only(bs), as inactivated images may not
1948 * be written to but do not count as read-only images.
1950 bool bdrv_is_writable(BlockDriverState *bs)
1952 return bdrv_is_writable_after_reopen(bs, NULL);
1955 static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
1956 BdrvChild *c, BdrvChildRole role,
1957 BlockReopenQueue *reopen_queue,
1958 uint64_t parent_perm, uint64_t parent_shared,
1959 uint64_t *nperm, uint64_t *nshared)
1961 assert(bs->drv && bs->drv->bdrv_child_perm);
1962 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
1963 parent_perm, parent_shared,
1965 /* TODO Take force_share from reopen_queue */
1966 if (child_bs && child_bs->force_share) {
1967 *nshared = BLK_PERM_ALL;
1972 * Check whether permissions on this node can be changed in a way that
1973 * @cumulative_perms and @cumulative_shared_perms are the new cumulative
1974 * permissions of all its parents. This involves checking whether all necessary
1975 * permission changes to child nodes can be performed.
1977 * Will set *tighten_restrictions to true if and only if new permissions have to
1978 * be taken or currently shared permissions are to be unshared. Otherwise,
1979 * errors are not fatal as long as the caller accepts that the restrictions
1980 * remain tighter than they need to be. The caller still has to abort the
1982 * @tighten_restrictions cannot be used together with @q: When reopening, we may
1983 * encounter fatal errors even though no restrictions are to be tightened. For
1984 * example, changing a node from RW to RO will fail if the WRITE permission is
1987 * A call to this function must always be followed by a call to bdrv_set_perm()
1988 * or bdrv_abort_perm_update().
1990 static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q,
1991 uint64_t cumulative_perms,
1992 uint64_t cumulative_shared_perms,
1993 GSList *ignore_children,
1994 bool *tighten_restrictions, Error **errp)
1996 BlockDriver *drv = bs->drv;
2000 assert(!q || !tighten_restrictions);
2002 if (tighten_restrictions) {
2003 uint64_t current_perms, current_shared;
2004 uint64_t added_perms, removed_shared_perms;
2006 bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared);
2008 added_perms = cumulative_perms & ~current_perms;
2009 removed_shared_perms = current_shared & ~cumulative_shared_perms;
2011 *tighten_restrictions = added_perms || removed_shared_perms;
2014 /* Write permissions never work with read-only images */
2015 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2016 !bdrv_is_writable_after_reopen(bs, q))
2018 if (!bdrv_is_writable_after_reopen(bs, NULL)) {
2019 error_setg(errp, "Block node is read-only");
2021 uint64_t current_perms, current_shared;
2022 bdrv_get_cumulative_perm(bs, ¤t_perms, ¤t_shared);
2023 if (current_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
2024 error_setg(errp, "Cannot make block node read-only, there is "
2027 error_setg(errp, "Cannot make block node read-only and create "
2036 * Unaligned requests will automatically be aligned to bl.request_alignment
2037 * and without RESIZE we can't extend requests to write to space beyond the
2038 * end of the image, so it's required that the image size is aligned.
2040 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2041 !(cumulative_perms & BLK_PERM_RESIZE))
2043 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) {
2044 error_setg(errp, "Cannot get 'write' permission without 'resize': "
2045 "Image size is not a multiple of request "
2051 /* Check this node */
2056 if (drv->bdrv_check_perm) {
2057 return drv->bdrv_check_perm(bs, cumulative_perms,
2058 cumulative_shared_perms, errp);
2061 /* Drivers that never have children can omit .bdrv_child_perm() */
2062 if (!drv->bdrv_child_perm) {
2063 assert(QLIST_EMPTY(&bs->children));
2067 /* Check all children */
2068 QLIST_FOREACH(c, &bs->children, next) {
2069 uint64_t cur_perm, cur_shared;
2070 bool child_tighten_restr;
2072 bdrv_child_perm(bs, c->bs, c, c->role, q,
2073 cumulative_perms, cumulative_shared_perms,
2074 &cur_perm, &cur_shared);
2075 ret = bdrv_child_check_perm(c, q, cur_perm, cur_shared, ignore_children,
2076 tighten_restrictions ? &child_tighten_restr
2079 if (tighten_restrictions) {
2080 *tighten_restrictions |= child_tighten_restr;
2091 * Notifies drivers that after a previous bdrv_check_perm() call, the
2092 * permission update is not performed and any preparations made for it (e.g.
2093 * taken file locks) need to be undone.
2095 * This function recursively notifies all child nodes.
2097 static void bdrv_abort_perm_update(BlockDriverState *bs)
2099 BlockDriver *drv = bs->drv;
2106 if (drv->bdrv_abort_perm_update) {
2107 drv->bdrv_abort_perm_update(bs);
2110 QLIST_FOREACH(c, &bs->children, next) {
2111 bdrv_child_abort_perm_update(c);
2115 static void bdrv_set_perm(BlockDriverState *bs)
2117 uint64_t cumulative_perms, cumulative_shared_perms;
2118 BlockDriver *drv = bs->drv;
2125 bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms);
2127 /* Update this node */
2128 if (drv->bdrv_set_perm) {
2129 drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
2132 /* Drivers that never have children can omit .bdrv_child_perm() */
2133 if (!drv->bdrv_child_perm) {
2134 assert(QLIST_EMPTY(&bs->children));
2138 /* Update all children */
2139 QLIST_FOREACH(c, &bs->children, next) {
2140 bdrv_child_set_perm(c);
2144 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
2145 uint64_t *shared_perm)
2148 uint64_t cumulative_perms = 0;
2149 uint64_t cumulative_shared_perms = BLK_PERM_ALL;
2151 QLIST_FOREACH(c, &bs->parents, next_parent) {
2152 cumulative_perms |= c->perm;
2153 cumulative_shared_perms &= c->shared_perm;
2156 *perm = cumulative_perms;
2157 *shared_perm = cumulative_shared_perms;
2160 static char *bdrv_child_user_desc(BdrvChild *c)
2162 if (c->klass->get_parent_desc) {
2163 return c->klass->get_parent_desc(c);
2166 return g_strdup("another user");
2169 char *bdrv_perm_names(uint64_t perm)
2175 { BLK_PERM_CONSISTENT_READ, "consistent read" },
2176 { BLK_PERM_WRITE, "write" },
2177 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
2178 { BLK_PERM_RESIZE, "resize" },
2179 { BLK_PERM_GRAPH_MOD, "change children" },
2183 GString *result = g_string_sized_new(30);
2184 struct perm_name *p;
2186 for (p = permissions; p->name; p++) {
2187 if (perm & p->perm) {
2188 if (result->len > 0) {
2189 g_string_append(result, ", ");
2191 g_string_append(result, p->name);
2195 return g_string_free(result, FALSE);
2199 * Checks whether a new reference to @bs can be added if the new user requires
2200 * @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is
2201 * set, the BdrvChild objects in this list are ignored in the calculations;
2202 * this allows checking permission updates for an existing reference.
2204 * See bdrv_check_perm() for the semantics of @tighten_restrictions.
2206 * Needs to be followed by a call to either bdrv_set_perm() or
2207 * bdrv_abort_perm_update(). */
2208 static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q,
2209 uint64_t new_used_perm,
2210 uint64_t new_shared_perm,
2211 GSList *ignore_children,
2212 bool *tighten_restrictions,
2216 uint64_t cumulative_perms = new_used_perm;
2217 uint64_t cumulative_shared_perms = new_shared_perm;
2219 assert(!q || !tighten_restrictions);
2221 /* There is no reason why anyone couldn't tolerate write_unchanged */
2222 assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED);
2224 QLIST_FOREACH(c, &bs->parents, next_parent) {
2225 if (g_slist_find(ignore_children, c)) {
2229 if ((new_used_perm & c->shared_perm) != new_used_perm) {
2230 char *user = bdrv_child_user_desc(c);
2231 char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm);
2233 if (tighten_restrictions) {
2234 *tighten_restrictions = true;
2237 error_setg(errp, "Conflicts with use by %s as '%s', which does not "
2239 user, c->name, perm_names, bdrv_get_node_name(c->bs));
2245 if ((c->perm & new_shared_perm) != c->perm) {
2246 char *user = bdrv_child_user_desc(c);
2247 char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm);
2249 if (tighten_restrictions) {
2250 *tighten_restrictions = true;
2253 error_setg(errp, "Conflicts with use by %s as '%s', which uses "
2255 user, c->name, perm_names, bdrv_get_node_name(c->bs));
2261 cumulative_perms |= c->perm;
2262 cumulative_shared_perms &= c->shared_perm;
2265 return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms,
2266 ignore_children, tighten_restrictions, errp);
2269 /* Needs to be followed by a call to either bdrv_child_set_perm() or
2270 * bdrv_child_abort_perm_update(). */
2271 static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
2272 uint64_t perm, uint64_t shared,
2273 GSList *ignore_children,
2274 bool *tighten_restrictions, Error **errp)
2278 ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c);
2279 ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children,
2280 tighten_restrictions, errp);
2281 g_slist_free(ignore_children);
2287 if (!c->has_backup_perm) {
2288 c->has_backup_perm = true;
2289 c->backup_perm = c->perm;
2290 c->backup_shared_perm = c->shared_perm;
2293 * Note: it's OK if c->has_backup_perm was already set, as we can find the
2294 * same child twice during check_perm procedure
2298 c->shared_perm = shared;
2303 static void bdrv_child_set_perm(BdrvChild *c)
2305 c->has_backup_perm = false;
2307 bdrv_set_perm(c->bs);
2310 static void bdrv_child_abort_perm_update(BdrvChild *c)
2312 if (c->has_backup_perm) {
2313 c->perm = c->backup_perm;
2314 c->shared_perm = c->backup_shared_perm;
2315 c->has_backup_perm = false;
2318 bdrv_abort_perm_update(c->bs);
2321 static int bdrv_refresh_perms(BlockDriverState *bs, bool *tighten_restrictions,
2325 uint64_t perm, shared_perm;
2327 bdrv_get_cumulative_perm(bs, &perm, &shared_perm);
2328 ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL,
2329 tighten_restrictions, errp);
2331 bdrv_abort_perm_update(bs);
2339 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
2342 Error *local_err = NULL;
2344 bool tighten_restrictions;
2346 ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL,
2347 &tighten_restrictions, &local_err);
2349 bdrv_child_abort_perm_update(c);
2350 if (tighten_restrictions) {
2351 error_propagate(errp, local_err);
2354 * Our caller may intend to only loosen restrictions and
2355 * does not expect this function to fail. Errors are not
2356 * fatal in such a case, so we can just hide them from our
2359 error_free(local_err);
2365 bdrv_child_set_perm(c);
2370 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
2372 uint64_t parent_perms, parent_shared;
2373 uint64_t perms, shared;
2375 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
2376 bdrv_child_perm(bs, c->bs, c, c->role, NULL,
2377 parent_perms, parent_shared, &perms, &shared);
2379 return bdrv_child_try_set_perm(c, perms, shared, errp);
2383 * Default implementation for .bdrv_child_perm() for block filters:
2384 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the
2387 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
2389 BlockReopenQueue *reopen_queue,
2390 uint64_t perm, uint64_t shared,
2391 uint64_t *nperm, uint64_t *nshared)
2393 *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
2394 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
2397 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c,
2399 BlockReopenQueue *reopen_queue,
2400 uint64_t perm, uint64_t shared,
2401 uint64_t *nperm, uint64_t *nshared)
2403 assert(role & BDRV_CHILD_COW);
2406 * We want consistent read from backing files if the parent needs it.
2407 * No other operations are performed on backing files.
2409 perm &= BLK_PERM_CONSISTENT_READ;
2412 * If the parent can deal with changing data, we're okay with a
2413 * writable and resizable backing file.
2414 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too?
2416 if (shared & BLK_PERM_WRITE) {
2417 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
2422 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD |
2423 BLK_PERM_WRITE_UNCHANGED;
2425 if (bs->open_flags & BDRV_O_INACTIVE) {
2426 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2433 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c,
2435 BlockReopenQueue *reopen_queue,
2436 uint64_t perm, uint64_t shared,
2437 uint64_t *nperm, uint64_t *nshared)
2441 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA));
2443 flags = bdrv_reopen_get_flags(reopen_queue, bs);
2446 * Apart from the modifications below, the same permissions are
2447 * forwarded and left alone as for filters
2449 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2450 perm, shared, &perm, &shared);
2452 if (role & BDRV_CHILD_METADATA) {
2453 /* Format drivers may touch metadata even if the guest doesn't write */
2454 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
2455 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2459 * bs->file always needs to be consistent because of the
2460 * metadata. We can never allow other users to resize or write
2463 if (!(flags & BDRV_O_NO_IO)) {
2464 perm |= BLK_PERM_CONSISTENT_READ;
2466 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
2469 if (role & BDRV_CHILD_DATA) {
2471 * Technically, everything in this block is a subset of the
2472 * BDRV_CHILD_METADATA path taken above, and so this could
2473 * be an "else if" branch. However, that is not obvious, and
2474 * this function is not performance critical, therefore we let
2475 * this be an independent "if".
2479 * We cannot allow other users to resize the file because the
2480 * format driver might have some assumptions about the size
2481 * (e.g. because it is stored in metadata, or because the file
2482 * is split into fixed-size data files).
2484 shared &= ~BLK_PERM_RESIZE;
2487 * WRITE_UNCHANGED often cannot be performed as such on the
2488 * data file. For example, the qcow2 driver may still need to
2489 * write copied clusters on copy-on-read.
2491 if (perm & BLK_PERM_WRITE_UNCHANGED) {
2492 perm |= BLK_PERM_WRITE;
2496 * If the data file is written to, the format driver may
2497 * expect to be able to resize it by writing beyond the EOF.
2499 if (perm & BLK_PERM_WRITE) {
2500 perm |= BLK_PERM_RESIZE;
2504 if (bs->open_flags & BDRV_O_INACTIVE) {
2505 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2512 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
2513 BdrvChildRole role, BlockReopenQueue *reopen_queue,
2514 uint64_t perm, uint64_t shared,
2515 uint64_t *nperm, uint64_t *nshared)
2517 if (role & BDRV_CHILD_FILTERED) {
2518 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
2520 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2521 perm, shared, nperm, nshared);
2522 } else if (role & BDRV_CHILD_COW) {
2523 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA)));
2524 bdrv_default_perms_for_cow(bs, c, role, reopen_queue,
2525 perm, shared, nperm, nshared);
2526 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) {
2527 bdrv_default_perms_for_storage(bs, c, role, reopen_queue,
2528 perm, shared, nperm, nshared);
2530 g_assert_not_reached();
2534 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
2536 static const uint64_t permissions[] = {
2537 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ,
2538 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE,
2539 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED,
2540 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE,
2541 [BLOCK_PERMISSION_GRAPH_MOD] = BLK_PERM_GRAPH_MOD,
2544 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX);
2545 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1);
2547 assert(qapi_perm < BLOCK_PERMISSION__MAX);
2549 return permissions[qapi_perm];
2552 static void bdrv_replace_child_noperm(BdrvChild *child,
2553 BlockDriverState *new_bs)
2555 BlockDriverState *old_bs = child->bs;
2556 int new_bs_quiesce_counter;
2559 assert(!child->frozen);
2561 if (old_bs && new_bs) {
2562 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
2565 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0);
2566 drain_saldo = new_bs_quiesce_counter - child->parent_quiesce_counter;
2569 * If the new child node is drained but the old one was not, flush
2570 * all outstanding requests to the old child node.
2572 while (drain_saldo > 0 && child->klass->drained_begin) {
2573 bdrv_parent_drained_begin_single(child, true);
2578 /* Detach first so that the recursive drain sections coming from @child
2579 * are already gone and we only end the drain sections that came from
2581 if (child->klass->detach) {
2582 child->klass->detach(child);
2584 QLIST_REMOVE(child, next_parent);
2590 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
2593 * Detaching the old node may have led to the new node's
2594 * quiesce_counter having been decreased. Not a problem, we
2595 * just need to recognize this here and then invoke
2596 * drained_end appropriately more often.
2598 assert(new_bs->quiesce_counter <= new_bs_quiesce_counter);
2599 drain_saldo += new_bs->quiesce_counter - new_bs_quiesce_counter;
2601 /* Attach only after starting new drained sections, so that recursive
2602 * drain sections coming from @child don't get an extra .drained_begin
2604 if (child->klass->attach) {
2605 child->klass->attach(child);
2610 * If the old child node was drained but the new one is not, allow
2611 * requests to come in only after the new node has been attached.
2613 while (drain_saldo < 0 && child->klass->drained_end) {
2614 bdrv_parent_drained_end_single(child);
2620 * Updates @child to change its reference to point to @new_bs, including
2621 * checking and applying the necessary permission updates both to the old node
2624 * NULL is passed as @new_bs for removing the reference before freeing @child.
2626 * If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this
2627 * function uses bdrv_set_perm() to update the permissions according to the new
2628 * reference that @new_bs gets.
2630 * Callers must ensure that child->frozen is false.
2632 static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
2634 BlockDriverState *old_bs = child->bs;
2636 /* Asserts that child->frozen == false */
2637 bdrv_replace_child_noperm(child, new_bs);
2640 * Start with the new node's permissions. If @new_bs is a (direct
2641 * or indirect) child of @old_bs, we must complete the permission
2642 * update on @new_bs before we loosen the restrictions on @old_bs.
2643 * Otherwise, bdrv_check_perm() on @old_bs would re-initiate
2644 * updating the permissions of @new_bs, and thus not purely loosen
2648 bdrv_set_perm(new_bs);
2652 bool tighten_restrictions;
2655 * Update permissions for old node. We're just taking a parent away, so
2656 * we're loosening restrictions. Errors of permission update are not
2657 * fatal in this case, ignore them.
2659 bdrv_refresh_perms(old_bs, &tighten_restrictions, NULL);
2660 assert(tighten_restrictions == false);
2662 /* When the parent requiring a non-default AioContext is removed, the
2663 * node moves back to the main AioContext */
2664 bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL);
2669 * This function steals the reference to child_bs from the caller.
2670 * That reference is later dropped by bdrv_root_unref_child().
2672 * On failure NULL is returned, errp is set and the reference to
2673 * child_bs is also dropped.
2675 * The caller must hold the AioContext lock @child_bs, but not that of @ctx
2676 * (unless @child_bs is already in @ctx).
2678 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
2679 const char *child_name,
2680 const BdrvChildClass *child_class,
2681 BdrvChildRole child_role,
2683 uint64_t perm, uint64_t shared_perm,
2684 void *opaque, Error **errp)
2687 Error *local_err = NULL;
2690 ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, NULL,
2693 bdrv_abort_perm_update(child_bs);
2694 bdrv_unref(child_bs);
2698 child = g_new(BdrvChild, 1);
2699 *child = (BdrvChild) {
2701 .name = g_strdup(child_name),
2702 .klass = child_class,
2705 .shared_perm = shared_perm,
2709 /* If the AioContexts don't match, first try to move the subtree of
2710 * child_bs into the AioContext of the new parent. If this doesn't work,
2711 * try moving the parent into the AioContext of child_bs instead. */
2712 if (bdrv_get_aio_context(child_bs) != ctx) {
2713 ret = bdrv_try_set_aio_context(child_bs, ctx, &local_err);
2714 if (ret < 0 && child_class->can_set_aio_ctx) {
2715 GSList *ignore = g_slist_prepend(NULL, child);
2716 ctx = bdrv_get_aio_context(child_bs);
2717 if (child_class->can_set_aio_ctx(child, ctx, &ignore, NULL)) {
2718 error_free(local_err);
2720 g_slist_free(ignore);
2721 ignore = g_slist_prepend(NULL, child);
2722 child_class->set_aio_ctx(child, ctx, &ignore);
2724 g_slist_free(ignore);
2727 error_propagate(errp, local_err);
2729 bdrv_abort_perm_update(child_bs);
2730 bdrv_unref(child_bs);
2735 /* This performs the matching bdrv_set_perm() for the above check. */
2736 bdrv_replace_child(child, child_bs);
2742 * This function transfers the reference to child_bs from the caller
2743 * to parent_bs. That reference is later dropped by parent_bs on
2744 * bdrv_close() or if someone calls bdrv_unref_child().
2746 * On failure NULL is returned, errp is set and the reference to
2747 * child_bs is also dropped.
2749 * If @parent_bs and @child_bs are in different AioContexts, the caller must
2750 * hold the AioContext lock for @child_bs, but not for @parent_bs.
2752 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
2753 BlockDriverState *child_bs,
2754 const char *child_name,
2755 const BdrvChildClass *child_class,
2756 BdrvChildRole child_role,
2760 uint64_t perm, shared_perm;
2762 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
2764 assert(parent_bs->drv);
2765 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
2766 perm, shared_perm, &perm, &shared_perm);
2768 child = bdrv_root_attach_child(child_bs, child_name, child_class,
2769 child_role, bdrv_get_aio_context(parent_bs),
2770 perm, shared_perm, parent_bs, errp);
2771 if (child == NULL) {
2775 QLIST_INSERT_HEAD(&parent_bs->children, child, next);
2779 static void bdrv_detach_child(BdrvChild *child)
2781 QLIST_SAFE_REMOVE(child, next);
2783 bdrv_replace_child(child, NULL);
2785 g_free(child->name);
2789 /* Callers must ensure that child->frozen is false. */
2790 void bdrv_root_unref_child(BdrvChild *child)
2792 BlockDriverState *child_bs;
2794 child_bs = child->bs;
2795 bdrv_detach_child(child);
2796 bdrv_unref(child_bs);
2800 * Clear all inherits_from pointers from children and grandchildren of
2801 * @root that point to @root, where necessary.
2803 static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child)
2807 if (child->bs->inherits_from == root) {
2809 * Remove inherits_from only when the last reference between root and
2810 * child->bs goes away.
2812 QLIST_FOREACH(c, &root->children, next) {
2813 if (c != child && c->bs == child->bs) {
2818 child->bs->inherits_from = NULL;
2822 QLIST_FOREACH(c, &child->bs->children, next) {
2823 bdrv_unset_inherits_from(root, c);
2827 /* Callers must ensure that child->frozen is false. */
2828 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
2830 if (child == NULL) {
2834 bdrv_unset_inherits_from(parent, child);
2835 bdrv_root_unref_child(child);
2839 static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
2842 QLIST_FOREACH(c, &bs->parents, next_parent) {
2843 if (c->klass->change_media) {
2844 c->klass->change_media(c, load);
2849 /* Return true if you can reach parent going through child->inherits_from
2850 * recursively. If parent or child are NULL, return false */
2851 static bool bdrv_inherits_from_recursive(BlockDriverState *child,
2852 BlockDriverState *parent)
2854 while (child && child != parent) {
2855 child = child->inherits_from;
2858 return child != NULL;
2862 * Return the BdrvChildRole for @bs's backing child. bs->backing is
2863 * mostly used for COW backing children (role = COW), but also for
2864 * filtered children (role = FILTERED | PRIMARY).
2866 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
2868 if (bs->drv && bs->drv->is_filter) {
2869 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
2871 return BDRV_CHILD_COW;
2876 * Sets the bs->backing link of a BDS. A new reference is created; callers
2877 * which don't need their own reference any more must call bdrv_unref().
2879 void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
2882 bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
2883 bdrv_inherits_from_recursive(backing_hd, bs);
2885 if (bdrv_is_backing_chain_frozen(bs, child_bs(bs->backing), errp)) {
2890 bdrv_ref(backing_hd);
2894 /* Cannot be frozen, we checked that above */
2895 bdrv_unref_child(bs, bs->backing);
2903 bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_of_bds,
2904 bdrv_backing_role(bs), errp);
2905 /* If backing_hd was already part of bs's backing chain, and
2906 * inherits_from pointed recursively to bs then let's update it to
2907 * point directly to bs (else it will become NULL). */
2908 if (bs->backing && update_inherits_from) {
2909 backing_hd->inherits_from = bs;
2913 bdrv_refresh_limits(bs, NULL);
2917 * Opens the backing file for a BlockDriverState if not yet open
2919 * bdref_key specifies the key for the image's BlockdevRef in the options QDict.
2920 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
2921 * itself, all options starting with "${bdref_key}." are considered part of the
2924 * TODO Can this be unified with bdrv_open_image()?
2926 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
2927 const char *bdref_key, Error **errp)
2929 char *backing_filename = NULL;
2930 char *bdref_key_dot;
2931 const char *reference = NULL;
2933 bool implicit_backing = false;
2934 BlockDriverState *backing_hd;
2936 QDict *tmp_parent_options = NULL;
2937 Error *local_err = NULL;
2939 if (bs->backing != NULL) {
2943 /* NULL means an empty set of options */
2944 if (parent_options == NULL) {
2945 tmp_parent_options = qdict_new();
2946 parent_options = tmp_parent_options;
2949 bs->open_flags &= ~BDRV_O_NO_BACKING;
2951 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
2952 qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
2953 g_free(bdref_key_dot);
2956 * Caution: while qdict_get_try_str() is fine, getting non-string
2957 * types would require more care. When @parent_options come from
2958 * -blockdev or blockdev_add, its members are typed according to
2959 * the QAPI schema, but when they come from -drive, they're all
2962 reference = qdict_get_try_str(parent_options, bdref_key);
2963 if (reference || qdict_haskey(options, "file.filename")) {
2964 /* keep backing_filename NULL */
2965 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
2966 qobject_unref(options);
2969 if (qdict_size(options) == 0) {
2970 /* If the user specifies options that do not modify the
2971 * backing file's behavior, we might still consider it the
2972 * implicit backing file. But it's easier this way, and
2973 * just specifying some of the backing BDS's options is
2974 * only possible with -drive anyway (otherwise the QAPI
2975 * schema forces the user to specify everything). */
2976 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
2979 backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
2982 error_propagate(errp, local_err);
2983 qobject_unref(options);
2988 if (!bs->drv || !bs->drv->supports_backing) {
2990 error_setg(errp, "Driver doesn't support backing files");
2991 qobject_unref(options);
2996 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
2997 qdict_put_str(options, "driver", bs->backing_format);
3000 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
3001 &child_of_bds, bdrv_backing_role(bs), errp);
3003 bs->open_flags |= BDRV_O_NO_BACKING;
3004 error_prepend(errp, "Could not open backing file: ");
3009 if (implicit_backing) {
3010 bdrv_refresh_filename(backing_hd);
3011 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
3012 backing_hd->filename);
3015 /* Hook up the backing file link; drop our reference, bs owns the
3016 * backing_hd reference now */
3017 bdrv_set_backing_hd(bs, backing_hd, &local_err);
3018 bdrv_unref(backing_hd);
3020 error_propagate(errp, local_err);
3025 qdict_del(parent_options, bdref_key);
3028 g_free(backing_filename);
3029 qobject_unref(tmp_parent_options);
3033 static BlockDriverState *
3034 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
3035 BlockDriverState *parent, const BdrvChildClass *child_class,
3036 BdrvChildRole child_role, bool allow_none, Error **errp)
3038 BlockDriverState *bs = NULL;
3039 QDict *image_options;
3040 char *bdref_key_dot;
3041 const char *reference;
3043 assert(child_class != NULL);
3045 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3046 qdict_extract_subqdict(options, &image_options, bdref_key_dot);
3047 g_free(bdref_key_dot);
3050 * Caution: while qdict_get_try_str() is fine, getting non-string
3051 * types would require more care. When @options come from
3052 * -blockdev or blockdev_add, its members are typed according to
3053 * the QAPI schema, but when they come from -drive, they're all
3056 reference = qdict_get_try_str(options, bdref_key);
3057 if (!filename && !reference && !qdict_size(image_options)) {
3059 error_setg(errp, "A block device must be specified for \"%s\"",
3062 qobject_unref(image_options);
3066 bs = bdrv_open_inherit(filename, reference, image_options, 0,
3067 parent, child_class, child_role, errp);
3073 qdict_del(options, bdref_key);
3078 * Opens a disk image whose options are given as BlockdevRef in another block
3081 * If allow_none is true, no image will be opened if filename is false and no
3082 * BlockdevRef is given. NULL will be returned, but errp remains unset.
3084 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
3085 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3086 * itself, all options starting with "${bdref_key}." are considered part of the
3089 * The BlockdevRef will be removed from the options QDict.
3091 BdrvChild *bdrv_open_child(const char *filename,
3092 QDict *options, const char *bdref_key,
3093 BlockDriverState *parent,
3094 const BdrvChildClass *child_class,
3095 BdrvChildRole child_role,
3096 bool allow_none, Error **errp)
3098 BlockDriverState *bs;
3100 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
3101 child_role, allow_none, errp);
3106 return bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
3111 * TODO Future callers may need to specify parent/child_class in order for
3112 * option inheritance to work. Existing callers use it for the root node.
3114 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
3116 BlockDriverState *bs = NULL;
3117 QObject *obj = NULL;
3118 QDict *qdict = NULL;
3119 const char *reference = NULL;
3122 if (ref->type == QTYPE_QSTRING) {
3123 reference = ref->u.reference;
3125 BlockdevOptions *options = &ref->u.definition;
3126 assert(ref->type == QTYPE_QDICT);
3128 v = qobject_output_visitor_new(&obj);
3129 visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
3130 visit_complete(v, &obj);
3132 qdict = qobject_to(QDict, obj);
3133 qdict_flatten(qdict);
3135 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for
3136 * compatibility with other callers) rather than what we want as the
3137 * real defaults. Apply the defaults here instead. */
3138 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
3139 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
3140 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
3141 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
3145 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp);
3152 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
3154 QDict *snapshot_options,
3157 /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
3158 char *tmp_filename = g_malloc0(PATH_MAX + 1);
3160 QemuOpts *opts = NULL;
3161 BlockDriverState *bs_snapshot = NULL;
3162 Error *local_err = NULL;
3165 /* if snapshot, we create a temporary backing file and open it
3166 instead of opening 'filename' directly */
3168 /* Get the required size from the image */
3169 total_size = bdrv_getlength(bs);
3170 if (total_size < 0) {
3171 error_setg_errno(errp, -total_size, "Could not get image size");
3175 /* Create the temporary image */
3176 ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);
3178 error_setg_errno(errp, -ret, "Could not get temporary filename");
3182 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
3184 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
3185 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
3186 qemu_opts_del(opts);
3188 error_prepend(errp, "Could not create temporary overlay '%s': ",
3193 /* Prepare options QDict for the temporary file */
3194 qdict_put_str(snapshot_options, "file.driver", "file");
3195 qdict_put_str(snapshot_options, "file.filename", tmp_filename);
3196 qdict_put_str(snapshot_options, "driver", "qcow2");
3198 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
3199 snapshot_options = NULL;
3204 /* bdrv_append() consumes a strong reference to bs_snapshot
3205 * (i.e. it will call bdrv_unref() on it) even on error, so in
3206 * order to be able to return one, we have to increase
3207 * bs_snapshot's refcount here */
3208 bdrv_ref(bs_snapshot);
3209 bdrv_append(bs_snapshot, bs, &local_err);
3211 error_propagate(errp, local_err);
3217 qobject_unref(snapshot_options);
3218 g_free(tmp_filename);
3223 * Opens a disk image (raw, qcow2, vmdk, ...)
3225 * options is a QDict of options to pass to the block drivers, or NULL for an
3226 * empty set of options. The reference to the QDict belongs to the block layer
3227 * after the call (even on failure), so if the caller intends to reuse the
3228 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
3230 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
3231 * If it is not NULL, the referenced BDS will be reused.
3233 * The reference parameter may be used to specify an existing block device which
3234 * should be opened. If specified, neither options nor a filename may be given,
3235 * nor can an existing BDS be reused (that is, *pbs has to be NULL).
3237 static BlockDriverState *bdrv_open_inherit(const char *filename,
3238 const char *reference,
3239 QDict *options, int flags,
3240 BlockDriverState *parent,
3241 const BdrvChildClass *child_class,
3242 BdrvChildRole child_role,
3246 BlockBackend *file = NULL;
3247 BlockDriverState *bs;
3248 BlockDriver *drv = NULL;
3250 const char *drvname;
3251 const char *backing;
3252 Error *local_err = NULL;
3253 QDict *snapshot_options = NULL;
3254 int snapshot_flags = 0;
3256 assert(!child_class || !flags);
3257 assert(!child_class == !parent);
3260 bool options_non_empty = options ? qdict_size(options) : false;
3261 qobject_unref(options);
3263 if (filename || options_non_empty) {
3264 error_setg(errp, "Cannot reference an existing block device with "
3265 "additional options or a new filename");
3269 bs = bdrv_lookup_bs(reference, reference, errp);
3280 /* NULL means an empty set of options */
3281 if (options == NULL) {
3282 options = qdict_new();
3285 /* json: syntax counts as explicit options, as if in the QDict */
3286 parse_json_protocol(options, &filename, &local_err);
3291 bs->explicit_options = qdict_clone_shallow(options);
3294 bool parent_is_format;
3297 parent_is_format = parent->drv->is_format;
3300 * parent->drv is not set yet because this node is opened for
3301 * (potential) format probing. That means that @parent is going
3302 * to be a format node.
3304 parent_is_format = true;
3307 bs->inherits_from = parent;
3308 child_class->inherit_options(child_role, parent_is_format,
3310 parent->open_flags, parent->options);
3313 ret = bdrv_fill_options(&options, filename, &flags, &local_err);
3319 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
3320 * Caution: getting a boolean member of @options requires care.
3321 * When @options come from -blockdev or blockdev_add, members are
3322 * typed according to the QAPI schema, but when they come from
3323 * -drive, they're all QString.
3325 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
3326 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
3327 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
3329 flags &= ~BDRV_O_RDWR;
3332 if (flags & BDRV_O_SNAPSHOT) {
3333 snapshot_options = qdict_new();
3334 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options,
3336 /* Let bdrv_backing_options() override "read-only" */
3337 qdict_del(options, BDRV_OPT_READ_ONLY);
3338 bdrv_inherited_options(BDRV_CHILD_COW, true,
3339 &flags, options, flags, options);
3342 bs->open_flags = flags;
3343 bs->options = options;
3344 options = qdict_clone_shallow(options);
3346 /* Find the right image format driver */
3347 /* See cautionary note on accessing @options above */
3348 drvname = qdict_get_try_str(options, "driver");
3350 drv = bdrv_find_format(drvname);
3352 error_setg(errp, "Unknown driver: '%s'", drvname);
3357 assert(drvname || !(flags & BDRV_O_PROTOCOL));
3359 /* See cautionary note on accessing @options above */
3360 backing = qdict_get_try_str(options, "backing");
3361 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
3362 (backing && *backing == '\0'))
3365 warn_report("Use of \"backing\": \"\" is deprecated; "
3366 "use \"backing\": null instead");
3368 flags |= BDRV_O_NO_BACKING;
3369 qdict_del(bs->explicit_options, "backing");
3370 qdict_del(bs->options, "backing");
3371 qdict_del(options, "backing");
3374 /* Open image file without format layer. This BlockBackend is only used for
3375 * probing, the block drivers will do their own bdrv_open_child() for the
3376 * same BDS, which is why we put the node name back into options. */
3377 if ((flags & BDRV_O_PROTOCOL) == 0) {
3378 BlockDriverState *file_bs;
3380 file_bs = bdrv_open_child_bs(filename, options, "file", bs,
3381 &child_of_bds, BDRV_CHILD_IMAGE,
3386 if (file_bs != NULL) {
3387 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only
3388 * looking at the header to guess the image format. This works even
3389 * in cases where a guest would not see a consistent state. */
3390 file = blk_new(bdrv_get_aio_context(file_bs), 0, BLK_PERM_ALL);
3391 blk_insert_bs(file, file_bs, &local_err);
3392 bdrv_unref(file_bs);
3397 qdict_put_str(options, "file", bdrv_get_node_name(file_bs));
3401 /* Image format probing */
3404 ret = find_image_format(file, filename, &drv, &local_err);
3409 * This option update would logically belong in bdrv_fill_options(),
3410 * but we first need to open bs->file for the probing to work, while
3411 * opening bs->file already requires the (mostly) final set of options
3412 * so that cache mode etc. can be inherited.
3414 * Adding the driver later is somewhat ugly, but it's not an option
3415 * that would ever be inherited, so it's correct. We just need to make
3416 * sure to update both bs->options (which has the full effective
3417 * options for bs) and options (which has file.* already removed).
3419 qdict_put_str(bs->options, "driver", drv->format_name);
3420 qdict_put_str(options, "driver", drv->format_name);
3422 error_setg(errp, "Must specify either driver or file");
3426 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
3427 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
3428 /* file must be NULL if a protocol BDS is about to be created
3429 * (the inverse results in an error message from bdrv_open_common()) */
3430 assert(!(flags & BDRV_O_PROTOCOL) || !file);
3432 /* Open the image */
3433 ret = bdrv_open_common(bs, file, options, &local_err);
3443 /* If there is a backing file, use it */
3444 if ((flags & BDRV_O_NO_BACKING) == 0) {
3445 ret = bdrv_open_backing_file(bs, options, "backing", &local_err);
3447 goto close_and_fail;
3451 /* Remove all children options and references
3452 * from bs->options and bs->explicit_options */
3453 QLIST_FOREACH(child, &bs->children, next) {
3454 char *child_key_dot;
3455 child_key_dot = g_strdup_printf("%s.", child->name);
3456 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot);
3457 qdict_extract_subqdict(bs->options, NULL, child_key_dot);
3458 qdict_del(bs->explicit_options, child->name);
3459 qdict_del(bs->options, child->name);
3460 g_free(child_key_dot);
3463 /* Check if any unknown options were used */
3464 if (qdict_size(options) != 0) {
3465 const QDictEntry *entry = qdict_first(options);
3466 if (flags & BDRV_O_PROTOCOL) {
3467 error_setg(errp, "Block protocol '%s' doesn't support the option "
3468 "'%s'", drv->format_name, entry->key);
3471 "Block format '%s' does not support the option '%s'",
3472 drv->format_name, entry->key);
3475 goto close_and_fail;
3478 bdrv_parent_cb_change_media(bs, true);
3480 qobject_unref(options);
3483 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
3484 * temporary snapshot afterwards. */
3485 if (snapshot_flags) {
3486 BlockDriverState *snapshot_bs;
3487 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags,
3488 snapshot_options, &local_err);
3489 snapshot_options = NULL;
3491 goto close_and_fail;
3493 /* We are not going to return bs but the overlay on top of it
3494 * (snapshot_bs); thus, we have to drop the strong reference to bs
3495 * (which we obtained by calling bdrv_new()). bs will not be deleted,
3496 * though, because the overlay still has a reference to it. */
3505 qobject_unref(snapshot_options);
3506 qobject_unref(bs->explicit_options);
3507 qobject_unref(bs->options);
3508 qobject_unref(options);
3510 bs->explicit_options = NULL;
3512 error_propagate(errp, local_err);
3517 qobject_unref(snapshot_options);
3518 qobject_unref(options);
3519 error_propagate(errp, local_err);
3523 BlockDriverState *bdrv_open(const char *filename, const char *reference,
3524 QDict *options, int flags, Error **errp)
3526 return bdrv_open_inherit(filename, reference, options, flags, NULL,
3530 /* Return true if the NULL-terminated @list contains @str */
3531 static bool is_str_in_list(const char *str, const char *const *list)
3535 for (i = 0; list[i] != NULL; i++) {
3536 if (!strcmp(str, list[i])) {
3545 * Check that every option set in @bs->options is also set in
3548 * Options listed in the common_options list and in
3549 * @bs->drv->mutable_opts are skipped.
3551 * Return 0 on success, otherwise return -EINVAL and set @errp.
3553 static int bdrv_reset_options_allowed(BlockDriverState *bs,
3554 const QDict *new_opts, Error **errp)
3556 const QDictEntry *e;
3557 /* These options are common to all block drivers and are handled
3558 * in bdrv_reopen_prepare() so they can be left out of @new_opts */
3559 const char *const common_options[] = {
3560 "node-name", "discard", "cache.direct", "cache.no-flush",
3561 "read-only", "auto-read-only", "detect-zeroes", NULL
3564 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) {
3565 if (!qdict_haskey(new_opts, e->key) &&
3566 !is_str_in_list(e->key, common_options) &&
3567 !is_str_in_list(e->key, bs->drv->mutable_opts)) {
3568 error_setg(errp, "Option '%s' cannot be reset "
3569 "to its default value", e->key);
3578 * Returns true if @child can be reached recursively from @bs
3580 static bool bdrv_recurse_has_child(BlockDriverState *bs,
3581 BlockDriverState *child)
3589 QLIST_FOREACH(c, &bs->children, next) {
3590 if (bdrv_recurse_has_child(c->bs, child)) {
3599 * Adds a BlockDriverState to a simple queue for an atomic, transactional
3600 * reopen of multiple devices.
3602 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT
3603 * already performed, or alternatively may be NULL a new BlockReopenQueue will
3604 * be created and initialized. This newly created BlockReopenQueue should be
3605 * passed back in for subsequent calls that are intended to be of the same
3608 * bs is the BlockDriverState to add to the reopen queue.
3610 * options contains the changed options for the associated bs
3611 * (the BlockReopenQueue takes ownership)
3613 * flags contains the open flags for the associated bs
3615 * returns a pointer to bs_queue, which is either the newly allocated
3616 * bs_queue, or the existing bs_queue being used.
3618 * bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple().
3620 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
3621 BlockDriverState *bs,
3623 const BdrvChildClass *klass,
3625 bool parent_is_format,
3626 QDict *parent_options,
3632 BlockReopenQueueEntry *bs_entry;
3634 QDict *old_options, *explicit_options, *options_copy;
3638 /* Make sure that the caller remembered to use a drained section. This is
3639 * important to avoid graph changes between the recursive queuing here and
3640 * bdrv_reopen_multiple(). */
3641 assert(bs->quiesce_counter > 0);
3643 if (bs_queue == NULL) {
3644 bs_queue = g_new0(BlockReopenQueue, 1);
3645 QTAILQ_INIT(bs_queue);
3649 options = qdict_new();
3652 /* Check if this BlockDriverState is already in the queue */
3653 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
3654 if (bs == bs_entry->state.bs) {
3660 * Precedence of options:
3661 * 1. Explicitly passed in options (highest)
3662 * 2. Retained from explicitly set options of bs
3663 * 3. Inherited from parent node
3664 * 4. Retained from effective options of bs
3667 /* Old explicitly set values (don't overwrite by inherited value) */
3668 if (bs_entry || keep_old_opts) {
3669 old_options = qdict_clone_shallow(bs_entry ?
3670 bs_entry->state.explicit_options :
3671 bs->explicit_options);
3672 bdrv_join_options(bs, options, old_options);
3673 qobject_unref(old_options);
3676 explicit_options = qdict_clone_shallow(options);
3678 /* Inherit from parent node */
3679 if (parent_options) {
3681 klass->inherit_options(role, parent_is_format, &flags, options,
3682 parent_flags, parent_options);
3684 flags = bdrv_get_flags(bs);
3687 if (keep_old_opts) {
3688 /* Old values are used for options that aren't set yet */
3689 old_options = qdict_clone_shallow(bs->options);
3690 bdrv_join_options(bs, options, old_options);
3691 qobject_unref(old_options);
3694 /* We have the final set of options so let's update the flags */
3695 options_copy = qdict_clone_shallow(options);
3696 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
3697 qemu_opts_absorb_qdict(opts, options_copy, NULL);
3698 update_flags_from_options(&flags, opts);
3699 qemu_opts_del(opts);
3700 qobject_unref(options_copy);
3702 /* bdrv_open_inherit() sets and clears some additional flags internally */
3703 flags &= ~BDRV_O_PROTOCOL;
3704 if (flags & BDRV_O_RDWR) {
3705 flags |= BDRV_O_ALLOW_RDWR;
3709 bs_entry = g_new0(BlockReopenQueueEntry, 1);
3710 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry);
3712 qobject_unref(bs_entry->state.options);
3713 qobject_unref(bs_entry->state.explicit_options);
3716 bs_entry->state.bs = bs;
3717 bs_entry->state.options = options;
3718 bs_entry->state.explicit_options = explicit_options;
3719 bs_entry->state.flags = flags;
3721 /* This needs to be overwritten in bdrv_reopen_prepare() */
3722 bs_entry->state.perm = UINT64_MAX;
3723 bs_entry->state.shared_perm = 0;
3726 * If keep_old_opts is false then it means that unspecified
3727 * options must be reset to their original value. We don't allow
3728 * resetting 'backing' but we need to know if the option is
3729 * missing in order to decide if we have to return an error.
3731 if (!keep_old_opts) {
3732 bs_entry->state.backing_missing =
3733 !qdict_haskey(options, "backing") &&
3734 !qdict_haskey(options, "backing.driver");
3737 QLIST_FOREACH(child, &bs->children, next) {
3738 QDict *new_child_options = NULL;
3739 bool child_keep_old = keep_old_opts;
3741 /* reopen can only change the options of block devices that were
3742 * implicitly created and inherited options. For other (referenced)
3743 * block devices, a syntax like "backing.foo" results in an error. */
3744 if (child->bs->inherits_from != bs) {
3748 /* Check if the options contain a child reference */
3749 if (qdict_haskey(options, child->name)) {
3750 const char *childref = qdict_get_try_str(options, child->name);
3752 * The current child must not be reopened if the child
3753 * reference is null or points to a different node.
3755 if (g_strcmp0(childref, child->bs->node_name)) {
3759 * If the child reference points to the current child then
3760 * reopen it with its existing set of options (note that
3761 * it can still inherit new options from the parent).
3763 child_keep_old = true;
3765 /* Extract child options ("child-name.*") */
3766 char *child_key_dot = g_strdup_printf("%s.", child->name);
3767 qdict_extract_subqdict(explicit_options, NULL, child_key_dot);
3768 qdict_extract_subqdict(options, &new_child_options, child_key_dot);
3769 g_free(child_key_dot);
3772 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
3773 child->klass, child->role, bs->drv->is_format,
3774 options, flags, child_keep_old);
3780 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
3781 BlockDriverState *bs,
3782 QDict *options, bool keep_old_opts)
3784 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false,
3785 NULL, 0, keep_old_opts);
3789 * Reopen multiple BlockDriverStates atomically & transactionally.
3791 * The queue passed in (bs_queue) must have been built up previous
3792 * via bdrv_reopen_queue().
3794 * Reopens all BDS specified in the queue, with the appropriate
3795 * flags. All devices are prepared for reopen, and failure of any
3796 * device will cause all device changes to be abandoned, and intermediate
3799 * If all devices prepare successfully, then the changes are committed
3802 * All affected nodes must be drained between bdrv_reopen_queue() and
3803 * bdrv_reopen_multiple().
3805 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
3808 BlockReopenQueueEntry *bs_entry, *next;
3810 assert(bs_queue != NULL);
3812 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
3813 assert(bs_entry->state.bs->quiesce_counter > 0);
3814 if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, errp)) {
3817 bs_entry->prepared = true;
3820 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
3821 BDRVReopenState *state = &bs_entry->state;
3822 ret = bdrv_check_perm(state->bs, bs_queue, state->perm,
3823 state->shared_perm, NULL, NULL, errp);
3827 /* Check if new_backing_bs would accept the new permissions */
3828 if (state->replace_backing_bs && state->new_backing_bs) {
3829 uint64_t nperm, nshared;
3830 bdrv_child_perm(state->bs, state->new_backing_bs,
3831 NULL, bdrv_backing_role(state->bs),
3832 bs_queue, state->perm, state->shared_perm,
3834 ret = bdrv_check_update_perm(state->new_backing_bs, NULL,
3835 nperm, nshared, NULL, NULL, errp);
3840 bs_entry->perms_checked = true;
3844 * If we reach this point, we have success and just need to apply the
3847 * Reverse order is used to comfort qcow2 driver: on commit it need to write
3848 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But
3849 * children are usually goes after parents in reopen-queue, so go from last
3852 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
3853 bdrv_reopen_commit(&bs_entry->state);
3858 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
3859 BDRVReopenState *state = &bs_entry->state;
3861 if (!bs_entry->perms_checked) {
3866 uint64_t perm, shared;
3868 bdrv_get_cumulative_perm(state->bs, &perm, &shared);
3869 assert(perm == state->perm);
3870 assert(shared == state->shared_perm);
3872 bdrv_set_perm(state->bs);
3874 bdrv_abort_perm_update(state->bs);
3875 if (state->replace_backing_bs && state->new_backing_bs) {
3876 bdrv_abort_perm_update(state->new_backing_bs);
3882 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
3883 BlockDriverState *bs = bs_entry->state.bs;
3885 if (bs->drv->bdrv_reopen_commit_post)
3886 bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
3890 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
3892 if (bs_entry->prepared) {
3893 bdrv_reopen_abort(&bs_entry->state);
3895 qobject_unref(bs_entry->state.explicit_options);
3896 qobject_unref(bs_entry->state.options);
3898 if (bs_entry->state.new_backing_bs) {
3899 bdrv_unref(bs_entry->state.new_backing_bs);
3908 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
3912 BlockReopenQueue *queue;
3913 QDict *opts = qdict_new();
3915 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
3917 bdrv_subtree_drained_begin(bs);
3918 queue = bdrv_reopen_queue(NULL, bs, opts, true);
3919 ret = bdrv_reopen_multiple(queue, errp);
3920 bdrv_subtree_drained_end(bs);
3925 static BlockReopenQueueEntry *find_parent_in_reopen_queue(BlockReopenQueue *q,
3928 BlockReopenQueueEntry *entry;
3930 QTAILQ_FOREACH(entry, q, entry) {
3931 BlockDriverState *bs = entry->state.bs;
3934 QLIST_FOREACH(child, &bs->children, next) {
3944 static void bdrv_reopen_perm(BlockReopenQueue *q, BlockDriverState *bs,
3945 uint64_t *perm, uint64_t *shared)
3948 BlockReopenQueueEntry *parent;
3949 uint64_t cumulative_perms = 0;
3950 uint64_t cumulative_shared_perms = BLK_PERM_ALL;
3952 QLIST_FOREACH(c, &bs->parents, next_parent) {
3953 parent = find_parent_in_reopen_queue(q, c);
3955 cumulative_perms |= c->perm;
3956 cumulative_shared_perms &= c->shared_perm;
3958 uint64_t nperm, nshared;
3960 bdrv_child_perm(parent->state.bs, bs, c, c->role, q,
3961 parent->state.perm, parent->state.shared_perm,
3964 cumulative_perms |= nperm;
3965 cumulative_shared_perms &= nshared;
3968 *perm = cumulative_perms;
3969 *shared = cumulative_shared_perms;
3972 static bool bdrv_reopen_can_attach(BlockDriverState *parent,
3974 BlockDriverState *new_child,
3977 AioContext *parent_ctx = bdrv_get_aio_context(parent);
3978 AioContext *child_ctx = bdrv_get_aio_context(new_child);
3982 ignore = g_slist_prepend(NULL, child);
3983 ret = bdrv_can_set_aio_context(new_child, parent_ctx, &ignore, NULL);
3984 g_slist_free(ignore);
3989 ignore = g_slist_prepend(NULL, child);
3990 ret = bdrv_can_set_aio_context(parent, child_ctx, &ignore, errp);
3991 g_slist_free(ignore);
3996 * Take a BDRVReopenState and check if the value of 'backing' in the
3997 * reopen_state->options QDict is valid or not.
3999 * If 'backing' is missing from the QDict then return 0.
4001 * If 'backing' contains the node name of the backing file of
4002 * reopen_state->bs then return 0.
4004 * If 'backing' contains a different node name (or is null) then check
4005 * whether the current backing file can be replaced with the new one.
4006 * If that's the case then reopen_state->replace_backing_bs is set to
4007 * true and reopen_state->new_backing_bs contains a pointer to the new
4008 * backing BlockDriverState (or NULL).
4010 * Return 0 on success, otherwise return < 0 and set @errp.
4012 static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state,
4015 BlockDriverState *bs = reopen_state->bs;
4016 BlockDriverState *overlay_bs, *below_bs, *new_backing_bs;
4020 value = qdict_get(reopen_state->options, "backing");
4021 if (value == NULL) {
4025 switch (qobject_type(value)) {
4027 new_backing_bs = NULL;
4030 str = qobject_get_try_str(value);
4031 new_backing_bs = bdrv_lookup_bs(NULL, str, errp);
4032 if (new_backing_bs == NULL) {
4034 } else if (bdrv_recurse_has_child(new_backing_bs, bs)) {
4035 error_setg(errp, "Making '%s' a backing file of '%s' "
4036 "would create a cycle", str, bs->node_name);
4041 /* 'backing' does not allow any other data type */
4042 g_assert_not_reached();
4046 * Check AioContext compatibility so that the bdrv_set_backing_hd() call in
4047 * bdrv_reopen_commit() won't fail.
4049 if (new_backing_bs) {
4050 if (!bdrv_reopen_can_attach(bs, bs->backing, new_backing_bs, errp)) {
4056 * Ensure that @bs can really handle backing files, because we are
4057 * about to give it one (or swap the existing one)
4059 if (bs->drv->is_filter) {
4060 /* Filters always have a file or a backing child */
4062 error_setg(errp, "'%s' is a %s filter node that does not support a "
4063 "backing child", bs->node_name, bs->drv->format_name);
4066 } else if (!bs->drv->supports_backing) {
4067 error_setg(errp, "Driver '%s' of node '%s' does not support backing "
4068 "files", bs->drv->format_name, bs->node_name);
4073 * Find the "actual" backing file by skipping all links that point
4074 * to an implicit node, if any (e.g. a commit filter node).
4075 * We cannot use any of the bdrv_skip_*() functions here because
4076 * those return the first explicit node, while we are looking for
4080 for (below_bs = bdrv_filter_or_cow_bs(overlay_bs);
4081 below_bs && below_bs->implicit;
4082 below_bs = bdrv_filter_or_cow_bs(overlay_bs))
4084 overlay_bs = below_bs;
4087 /* If we want to replace the backing file we need some extra checks */
4088 if (new_backing_bs != bdrv_filter_or_cow_bs(overlay_bs)) {
4089 /* Check for implicit nodes between bs and its backing file */
4090 if (bs != overlay_bs) {
4091 error_setg(errp, "Cannot change backing link if '%s' has "
4092 "an implicit backing file", bs->node_name);
4096 * Check if the backing link that we want to replace is frozen.
4098 * bdrv_filter_or_cow_child(overlay_bs) == overlay_bs->backing,
4099 * because we know that overlay_bs == bs, and that @bs
4100 * either is a filter that uses ->backing or a COW format BDS
4101 * with bs->drv->supports_backing == true.
4103 if (bdrv_is_backing_chain_frozen(overlay_bs,
4104 child_bs(overlay_bs->backing), errp))
4108 reopen_state->replace_backing_bs = true;
4109 if (new_backing_bs) {
4110 bdrv_ref(new_backing_bs);
4111 reopen_state->new_backing_bs = new_backing_bs;
4119 * Prepares a BlockDriverState for reopen. All changes are staged in the
4120 * 'opaque' field of the BDRVReopenState, which is used and allocated by
4121 * the block driver layer .bdrv_reopen_prepare()
4123 * bs is the BlockDriverState to reopen
4124 * flags are the new open flags
4125 * queue is the reopen queue
4127 * Returns 0 on success, non-zero on error. On error errp will be set
4130 * On failure, bdrv_reopen_abort() will be called to clean up any data.
4131 * It is the responsibility of the caller to then call the abort() or
4132 * commit() for any other BDS that have been left in a prepare() state
4135 int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
4140 Error *local_err = NULL;
4143 QDict *orig_reopen_opts;
4144 char *discard = NULL;
4146 bool drv_prepared = false;
4148 assert(reopen_state != NULL);
4149 assert(reopen_state->bs->drv != NULL);
4150 drv = reopen_state->bs->drv;
4152 /* This function and each driver's bdrv_reopen_prepare() remove
4153 * entries from reopen_state->options as they are processed, so
4154 * we need to make a copy of the original QDict. */
4155 orig_reopen_opts = qdict_clone_shallow(reopen_state->options);
4157 /* Process generic block layer options */
4158 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4159 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) {
4164 /* This was already called in bdrv_reopen_queue_child() so the flags
4165 * are up-to-date. This time we simply want to remove the options from
4166 * QemuOpts in order to indicate that they have been processed. */
4167 old_flags = reopen_state->flags;
4168 update_flags_from_options(&reopen_state->flags, opts);
4169 assert(old_flags == reopen_state->flags);
4171 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD);
4172 if (discard != NULL) {
4173 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) {
4174 error_setg(errp, "Invalid discard option");
4180 reopen_state->detect_zeroes =
4181 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err);
4183 error_propagate(errp, local_err);
4188 /* All other options (including node-name and driver) must be unchanged.
4189 * Put them back into the QDict, so that they are checked at the end
4190 * of this function. */
4191 qemu_opts_to_qdict(opts, reopen_state->options);
4193 /* If we are to stay read-only, do not allow permission change
4194 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
4195 * not set, or if the BDS still has copy_on_read enabled */
4196 read_only = !(reopen_state->flags & BDRV_O_RDWR);
4197 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
4199 error_propagate(errp, local_err);
4203 /* Calculate required permissions after reopening */
4204 bdrv_reopen_perm(queue, reopen_state->bs,
4205 &reopen_state->perm, &reopen_state->shared_perm);
4207 ret = bdrv_flush(reopen_state->bs);
4209 error_setg_errno(errp, -ret, "Error flushing drive");
4213 if (drv->bdrv_reopen_prepare) {
4215 * If a driver-specific option is missing, it means that we
4216 * should reset it to its default value.
4217 * But not all options allow that, so we need to check it first.
4219 ret = bdrv_reset_options_allowed(reopen_state->bs,
4220 reopen_state->options, errp);
4225 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
4227 if (local_err != NULL) {
4228 error_propagate(errp, local_err);
4230 bdrv_refresh_filename(reopen_state->bs);
4231 error_setg(errp, "failed while preparing to reopen image '%s'",
4232 reopen_state->bs->filename);
4237 /* It is currently mandatory to have a bdrv_reopen_prepare()
4238 * handler for each supported drv. */
4239 error_setg(errp, "Block format '%s' used by node '%s' "
4240 "does not support reopening files", drv->format_name,
4241 bdrv_get_device_or_node_name(reopen_state->bs));
4246 drv_prepared = true;
4249 * We must provide the 'backing' option if the BDS has a backing
4250 * file or if the image file has a backing file name as part of
4251 * its metadata. Otherwise the 'backing' option can be omitted.
4253 if (drv->supports_backing && reopen_state->backing_missing &&
4254 (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) {
4255 error_setg(errp, "backing is missing for '%s'",
4256 reopen_state->bs->node_name);
4262 * Allow changing the 'backing' option. The new value can be
4263 * either a reference to an existing node (using its node name)
4264 * or NULL to simply detach the current backing file.
4266 ret = bdrv_reopen_parse_backing(reopen_state, errp);
4270 qdict_del(reopen_state->options, "backing");
4272 /* Options that are not handled are only okay if they are unchanged
4273 * compared to the old state. It is expected that some options are only
4274 * used for the initial open, but not reopen (e.g. filename) */
4275 if (qdict_size(reopen_state->options)) {
4276 const QDictEntry *entry = qdict_first(reopen_state->options);
4279 QObject *new = entry->value;
4280 QObject *old = qdict_get(reopen_state->bs->options, entry->key);
4282 /* Allow child references (child_name=node_name) as long as they
4283 * point to the current child (i.e. everything stays the same). */
4284 if (qobject_type(new) == QTYPE_QSTRING) {
4286 QLIST_FOREACH(child, &reopen_state->bs->children, next) {
4287 if (!strcmp(child->name, entry->key)) {
4293 const char *str = qobject_get_try_str(new);
4294 if (!strcmp(child->bs->node_name, str)) {
4295 continue; /* Found child with this name, skip option */
4301 * TODO: When using -drive to specify blockdev options, all values
4302 * will be strings; however, when using -blockdev, blockdev-add or
4303 * filenames using the json:{} pseudo-protocol, they will be
4305 * In contrast, reopening options are (currently) always strings
4306 * (because you can only specify them through qemu-io; all other
4307 * callers do not specify any options).
4308 * Therefore, when using anything other than -drive to create a BDS,
4309 * this cannot detect non-string options as unchanged, because
4310 * qobject_is_equal() always returns false for objects of different
4311 * type. In the future, this should be remedied by correctly typing
4312 * all options. For now, this is not too big of an issue because
4313 * the user can simply omit options which cannot be changed anyway,
4314 * so they will stay unchanged.
4316 if (!qobject_is_equal(new, old)) {
4317 error_setg(errp, "Cannot change the option '%s'", entry->key);
4321 } while ((entry = qdict_next(reopen_state->options, entry)));
4326 /* Restore the original reopen_state->options QDict */
4327 qobject_unref(reopen_state->options);
4328 reopen_state->options = qobject_ref(orig_reopen_opts);
4331 if (ret < 0 && drv_prepared) {
4332 /* drv->bdrv_reopen_prepare() has succeeded, so we need to
4333 * call drv->bdrv_reopen_abort() before signaling an error
4334 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort()
4335 * when the respective bdrv_reopen_prepare() has failed) */
4336 if (drv->bdrv_reopen_abort) {
4337 drv->bdrv_reopen_abort(reopen_state);
4340 qemu_opts_del(opts);
4341 qobject_unref(orig_reopen_opts);
4347 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and
4348 * makes them final by swapping the staging BlockDriverState contents into
4349 * the active BlockDriverState contents.
4351 void bdrv_reopen_commit(BDRVReopenState *reopen_state)
4354 BlockDriverState *bs;
4357 assert(reopen_state != NULL);
4358 bs = reopen_state->bs;
4360 assert(drv != NULL);
4362 /* If there are any driver level actions to take */
4363 if (drv->bdrv_reopen_commit) {
4364 drv->bdrv_reopen_commit(reopen_state);
4367 /* set BDS specific flags now */
4368 qobject_unref(bs->explicit_options);
4369 qobject_unref(bs->options);
4371 bs->explicit_options = reopen_state->explicit_options;
4372 bs->options = reopen_state->options;
4373 bs->open_flags = reopen_state->flags;
4374 bs->read_only = !(reopen_state->flags & BDRV_O_RDWR);
4375 bs->detect_zeroes = reopen_state->detect_zeroes;
4377 if (reopen_state->replace_backing_bs) {
4378 qdict_del(bs->explicit_options, "backing");
4379 qdict_del(bs->options, "backing");
4382 /* Remove child references from bs->options and bs->explicit_options.
4383 * Child options were already removed in bdrv_reopen_queue_child() */
4384 QLIST_FOREACH(child, &bs->children, next) {
4385 qdict_del(bs->explicit_options, child->name);
4386 qdict_del(bs->options, child->name);
4390 * Change the backing file if a new one was specified. We do this
4391 * after updating bs->options, so bdrv_refresh_filename() (called
4392 * from bdrv_set_backing_hd()) has the new values.
4394 if (reopen_state->replace_backing_bs) {
4395 BlockDriverState *old_backing_bs = child_bs(bs->backing);
4396 assert(!old_backing_bs || !old_backing_bs->implicit);
4397 /* Abort the permission update on the backing bs we're detaching */
4398 if (old_backing_bs) {
4399 bdrv_abort_perm_update(old_backing_bs);
4401 bdrv_set_backing_hd(bs, reopen_state->new_backing_bs, &error_abort);
4404 bdrv_refresh_limits(bs, NULL);
4408 * Abort the reopen, and delete and free the staged changes in
4411 void bdrv_reopen_abort(BDRVReopenState *reopen_state)
4415 assert(reopen_state != NULL);
4416 drv = reopen_state->bs->drv;
4417 assert(drv != NULL);
4419 if (drv->bdrv_reopen_abort) {
4420 drv->bdrv_reopen_abort(reopen_state);
4425 static void bdrv_close(BlockDriverState *bs)
4427 BdrvAioNotifier *ban, *ban_next;
4428 BdrvChild *child, *next;
4430 assert(!bs->refcnt);
4432 bdrv_drained_begin(bs); /* complete I/O */
4434 bdrv_drain(bs); /* in case flush left pending I/O */
4437 if (bs->drv->bdrv_close) {
4438 /* Must unfreeze all children, so bdrv_unref_child() works */
4439 bs->drv->bdrv_close(bs);
4444 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
4445 bdrv_unref_child(bs, child);
4452 qatomic_set(&bs->copy_on_read, 0);
4453 bs->backing_file[0] = '\0';
4454 bs->backing_format[0] = '\0';
4455 bs->total_sectors = 0;
4456 bs->encrypted = false;
4458 qobject_unref(bs->options);
4459 qobject_unref(bs->explicit_options);
4461 bs->explicit_options = NULL;
4462 qobject_unref(bs->full_open_options);
4463 bs->full_open_options = NULL;
4465 bdrv_release_named_dirty_bitmaps(bs);
4466 assert(QLIST_EMPTY(&bs->dirty_bitmaps));
4468 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
4471 QLIST_INIT(&bs->aio_notifiers);
4472 bdrv_drained_end(bs);
4475 * If we're still inside some bdrv_drain_all_begin()/end() sections, end
4476 * them now since this BDS won't exist anymore when bdrv_drain_all_end()
4479 if (bs->quiesce_counter) {
4480 bdrv_drain_all_end_quiesce(bs);
4484 void bdrv_close_all(void)
4486 assert(job_next(NULL) == NULL);
4487 blk_exp_close_all();
4489 /* Drop references from requests still in flight, such as canceled block
4490 * jobs whose AIO context has not been polled yet */
4493 blk_remove_all_bs();
4494 blockdev_close_all_bdrv_states();
4496 assert(QTAILQ_EMPTY(&all_bdrv_states));
4499 static bool should_update_child(BdrvChild *c, BlockDriverState *to)
4505 if (c->klass->stay_at_node) {
4509 /* If the child @c belongs to the BDS @to, replacing the current
4510 * c->bs by @to would mean to create a loop.
4512 * Such a case occurs when appending a BDS to a backing chain.
4513 * For instance, imagine the following chain:
4515 * guest device -> node A -> further backing chain...
4517 * Now we create a new BDS B which we want to put on top of this
4518 * chain, so we first attach A as its backing node:
4523 * guest device -> node A -> further backing chain...
4525 * Finally we want to replace A by B. When doing that, we want to
4526 * replace all pointers to A by pointers to B -- except for the
4527 * pointer from B because (1) that would create a loop, and (2)
4528 * that pointer should simply stay intact:
4530 * guest device -> node B
4533 * node A -> further backing chain...
4535 * In general, when replacing a node A (c->bs) by a node B (@to),
4536 * if A is a child of B, that means we cannot replace A by B there
4537 * because that would create a loop. Silently detaching A from B
4538 * is also not really an option. So overall just leaving A in
4539 * place there is the most sensible choice.
4541 * We would also create a loop in any cases where @c is only
4542 * indirectly referenced by @to. Prevent this by returning false
4543 * if @c is found (by breadth-first search) anywhere in the whole
4548 found = g_hash_table_new(NULL, NULL);
4549 g_hash_table_add(found, to);
4550 queue = g_queue_new();
4551 g_queue_push_tail(queue, to);
4553 while (!g_queue_is_empty(queue)) {
4554 BlockDriverState *v = g_queue_pop_head(queue);
4557 QLIST_FOREACH(c2, &v->children, next) {
4563 if (g_hash_table_contains(found, c2->bs)) {
4567 g_queue_push_tail(queue, c2->bs);
4568 g_hash_table_add(found, c2->bs);
4572 g_queue_free(queue);
4573 g_hash_table_destroy(found);
4579 * With auto_skip=true bdrv_replace_node_common skips updating from parents
4580 * if it creates a parent-child relation loop or if parent is block-job.
4582 * With auto_skip=false the error is returned if from has a parent which should
4585 static void bdrv_replace_node_common(BlockDriverState *from,
4586 BlockDriverState *to,
4587 bool auto_skip, Error **errp)
4589 BdrvChild *c, *next;
4590 GSList *list = NULL, *p;
4591 uint64_t perm = 0, shared = BLK_PERM_ALL;
4594 /* Make sure that @from doesn't go away until we have successfully attached
4595 * all of its parents to @to. */
4598 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
4599 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to));
4600 bdrv_drained_begin(from);
4602 /* Put all parents into @list and calculate their cumulative permissions */
4603 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
4604 assert(c->bs == from);
4605 if (!should_update_child(c, to)) {
4609 error_setg(errp, "Should not change '%s' link to '%s'",
4610 c->name, from->node_name);
4614 error_setg(errp, "Cannot change '%s' link to '%s'",
4615 c->name, from->node_name);
4618 list = g_slist_prepend(list, c);
4620 shared &= c->shared_perm;
4623 /* Check whether the required permissions can be granted on @to, ignoring
4624 * all BdrvChild in @list so that they can't block themselves. */
4625 ret = bdrv_check_update_perm(to, NULL, perm, shared, list, NULL, errp);
4627 bdrv_abort_perm_update(to);
4631 /* Now actually perform the change. We performed the permission check for
4632 * all elements of @list at once, so set the permissions all at once at the
4634 for (p = list; p != NULL; p = p->next) {
4638 bdrv_replace_child_noperm(c, to);
4646 bdrv_drained_end(from);
4650 void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
4653 return bdrv_replace_node_common(from, to, true, errp);
4657 * Add new bs contents at the top of an image chain while the chain is
4658 * live, while keeping required fields on the top layer.
4660 * This will modify the BlockDriverState fields, and swap contents
4661 * between bs_new and bs_top. Both bs_new and bs_top are modified.
4663 * bs_new must not be attached to a BlockBackend.
4665 * This function does not create any image files.
4667 * bdrv_append() takes ownership of a bs_new reference and unrefs it because
4668 * that's what the callers commonly need. bs_new will be referenced by the old
4669 * parents of bs_top after bdrv_append() returns. If the caller needs to keep a
4670 * reference of its own, it must call bdrv_ref().
4672 void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
4675 Error *local_err = NULL;
4677 bdrv_set_backing_hd(bs_new, bs_top, &local_err);
4679 error_propagate(errp, local_err);
4683 bdrv_replace_node(bs_top, bs_new, &local_err);
4685 error_propagate(errp, local_err);
4686 bdrv_set_backing_hd(bs_new, NULL, &error_abort);
4690 /* bs_new is now referenced by its new parents, we don't need the
4691 * additional reference any more. */
4696 static void bdrv_delete(BlockDriverState *bs)
4698 assert(bdrv_op_blocker_is_empty(bs));
4699 assert(!bs->refcnt);
4701 /* remove from list, if necessary */
4702 if (bs->node_name[0] != '\0') {
4703 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
4705 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
4713 * Run consistency checks on an image
4715 * Returns 0 if the check could be completed (it doesn't mean that the image is
4716 * free of errors) or -errno when an internal error occurred. The results of the
4717 * check are stored in res.
4719 int coroutine_fn bdrv_co_check(BlockDriverState *bs,
4720 BdrvCheckResult *res, BdrvCheckMode fix)
4722 if (bs->drv == NULL) {
4725 if (bs->drv->bdrv_co_check == NULL) {
4729 memset(res, 0, sizeof(*res));
4730 return bs->drv->bdrv_co_check(bs, res, fix);
4736 * -EINVAL - backing format specified, but no file
4737 * -ENOSPC - can't update the backing file because no space is left in the
4739 * -ENOTSUP - format driver doesn't support changing the backing file
4741 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
4742 const char *backing_fmt, bool warn)
4744 BlockDriver *drv = bs->drv;
4751 /* Backing file format doesn't make sense without a backing file */
4752 if (backing_fmt && !backing_file) {
4756 if (warn && backing_file && !backing_fmt) {
4757 warn_report("Deprecated use of backing file without explicit "
4758 "backing format, use of this image requires "
4759 "potentially unsafe format probing");
4762 if (drv->bdrv_change_backing_file != NULL) {
4763 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
4769 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
4770 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
4771 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
4772 backing_file ?: "");
4778 * Finds the first non-filter node above bs in the chain between
4779 * active and bs. The returned node is either an immediate parent of
4780 * bs, or there are only filter nodes between the two.
4782 * Returns NULL if bs is not found in active's image chain,
4783 * or if active == bs.
4785 * Returns the bottommost base image if bs == NULL.
4787 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
4788 BlockDriverState *bs)
4790 bs = bdrv_skip_filters(bs);
4791 active = bdrv_skip_filters(active);
4794 BlockDriverState *next = bdrv_backing_chain_next(active);
4804 /* Given a BDS, searches for the base layer. */
4805 BlockDriverState *bdrv_find_base(BlockDriverState *bs)
4807 return bdrv_find_overlay(bs, NULL);
4811 * Return true if at least one of the COW (backing) and filter links
4812 * between @bs and @base is frozen. @errp is set if that's the case.
4813 * @base must be reachable from @bs, or NULL.
4815 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
4818 BlockDriverState *i;
4821 for (i = bs; i != base; i = child_bs(child)) {
4822 child = bdrv_filter_or_cow_child(i);
4824 if (child && child->frozen) {
4825 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
4826 child->name, i->node_name, child->bs->node_name);
4835 * Freeze all COW (backing) and filter links between @bs and @base.
4836 * If any of the links is already frozen the operation is aborted and
4837 * none of the links are modified.
4838 * @base must be reachable from @bs, or NULL.
4839 * Returns 0 on success. On failure returns < 0 and sets @errp.
4841 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
4844 BlockDriverState *i;
4847 if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
4851 for (i = bs; i != base; i = child_bs(child)) {
4852 child = bdrv_filter_or_cow_child(i);
4853 if (child && child->bs->never_freeze) {
4854 error_setg(errp, "Cannot freeze '%s' link to '%s'",
4855 child->name, child->bs->node_name);
4860 for (i = bs; i != base; i = child_bs(child)) {
4861 child = bdrv_filter_or_cow_child(i);
4863 child->frozen = true;
4871 * Unfreeze all COW (backing) and filter links between @bs and @base.
4872 * The caller must ensure that all links are frozen before using this
4874 * @base must be reachable from @bs, or NULL.
4876 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
4878 BlockDriverState *i;
4881 for (i = bs; i != base; i = child_bs(child)) {
4882 child = bdrv_filter_or_cow_child(i);
4884 assert(child->frozen);
4885 child->frozen = false;
4891 * Drops images above 'base' up to and including 'top', and sets the image
4892 * above 'top' to have base as its backing file.
4894 * Requires that the overlay to 'top' is opened r/w, so that the backing file
4895 * information in 'bs' can be properly updated.
4897 * E.g., this will convert the following chain:
4898 * bottom <- base <- intermediate <- top <- active
4902 * bottom <- base <- active
4904 * It is allowed for bottom==base, in which case it converts:
4906 * base <- intermediate <- top <- active
4912 * If backing_file_str is non-NULL, it will be used when modifying top's
4913 * overlay image metadata.
4916 * if active == top, that is considered an error
4919 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
4920 const char *backing_file_str)
4922 BlockDriverState *explicit_top = top;
4923 bool update_inherits_from;
4925 Error *local_err = NULL;
4927 g_autoptr(GSList) updated_children = NULL;
4931 bdrv_subtree_drained_begin(top);
4933 if (!top->drv || !base->drv) {
4937 /* Make sure that base is in the backing chain of top */
4938 if (!bdrv_chain_contains(top, base)) {
4942 /* If 'base' recursively inherits from 'top' then we should set
4943 * base->inherits_from to top->inherits_from after 'top' and all
4944 * other intermediate nodes have been dropped.
4945 * If 'top' is an implicit node (e.g. "commit_top") we should skip
4946 * it because no one inherits from it. We use explicit_top for that. */
4947 explicit_top = bdrv_skip_implicit_filters(explicit_top);
4948 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
4950 /* success - we can delete the intermediate states, and link top->base */
4951 /* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once
4952 * we've figured out how they should work. */
4953 if (!backing_file_str) {
4954 bdrv_refresh_filename(base);
4955 backing_file_str = base->filename;
4958 QLIST_FOREACH(c, &top->parents, next_parent) {
4959 updated_children = g_slist_prepend(updated_children, c);
4962 bdrv_replace_node_common(top, base, false, &local_err);
4964 error_report_err(local_err);
4968 for (p = updated_children; p; p = p->next) {
4971 if (c->klass->update_filename) {
4972 ret = c->klass->update_filename(c, base, backing_file_str,
4976 * TODO: Actually, we want to rollback all previous iterations
4977 * of this loop, and (which is almost impossible) previous
4978 * bdrv_replace_node()...
4980 * Note, that c->klass->update_filename may lead to permission
4981 * update, so it's a bad idea to call it inside permission
4982 * update transaction of bdrv_replace_node.
4984 error_report_err(local_err);
4990 if (update_inherits_from) {
4991 base->inherits_from = explicit_top->inherits_from;
4996 bdrv_subtree_drained_end(top);
5002 * Implementation of BlockDriver.bdrv_get_allocated_file_size() that
5003 * sums the size of all data-bearing children. (This excludes backing
5006 static int64_t bdrv_sum_allocated_file_size(BlockDriverState *bs)
5009 int64_t child_size, sum = 0;
5011 QLIST_FOREACH(child, &bs->children, next) {
5012 if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
5013 BDRV_CHILD_FILTERED))
5015 child_size = bdrv_get_allocated_file_size(child->bs);
5016 if (child_size < 0) {
5027 * Length of a allocated file in bytes. Sparse files are counted by actual
5028 * allocated space. Return < 0 if error or unknown.
5030 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs)
5032 BlockDriver *drv = bs->drv;
5036 if (drv->bdrv_get_allocated_file_size) {
5037 return drv->bdrv_get_allocated_file_size(bs);
5040 if (drv->bdrv_file_open) {
5042 * Protocol drivers default to -ENOTSUP (most of their data is
5043 * not stored in any of their children (if they even have any),
5044 * so there is no generic way to figure it out).
5047 } else if (drv->is_filter) {
5048 /* Filter drivers default to the size of their filtered child */
5049 return bdrv_get_allocated_file_size(bdrv_filter_bs(bs));
5051 /* Other drivers default to summing their children's sizes */
5052 return bdrv_sum_allocated_file_size(bs);
5058 * @drv: Format driver
5059 * @opts: Creation options for new image
5060 * @in_bs: Existing image containing data for new image (may be NULL)
5061 * @errp: Error object
5062 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
5065 * Calculate file size required to create a new image.
5067 * If @in_bs is given then space for allocated clusters and zero clusters
5068 * from that image are included in the calculation. If @opts contains a
5069 * backing file that is shared by @in_bs then backing clusters may be omitted
5070 * from the calculation.
5072 * If @in_bs is NULL then the calculation includes no allocated clusters
5073 * unless a preallocation option is given in @opts.
5075 * Note that @in_bs may use a different BlockDriver from @drv.
5077 * If an error occurs the @errp pointer is set.
5079 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
5080 BlockDriverState *in_bs, Error **errp)
5082 if (!drv->bdrv_measure) {
5083 error_setg(errp, "Block driver '%s' does not support size measurement",
5088 return drv->bdrv_measure(opts, in_bs, errp);
5092 * Return number of sectors on success, -errno on error.
5094 int64_t bdrv_nb_sectors(BlockDriverState *bs)
5096 BlockDriver *drv = bs->drv;
5101 if (drv->has_variable_length) {
5102 int ret = refresh_total_sectors(bs, bs->total_sectors);
5107 return bs->total_sectors;
5111 * Return length in bytes on success, -errno on error.
5112 * The length is always a multiple of BDRV_SECTOR_SIZE.
5114 int64_t bdrv_getlength(BlockDriverState *bs)
5116 int64_t ret = bdrv_nb_sectors(bs);
5121 if (ret > INT64_MAX / BDRV_SECTOR_SIZE) {
5124 return ret * BDRV_SECTOR_SIZE;
5127 /* return 0 as number of sectors if no device present or error */
5128 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
5130 int64_t nb_sectors = bdrv_nb_sectors(bs);
5132 *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
5135 bool bdrv_is_sg(BlockDriverState *bs)
5141 * Return whether the given node supports compressed writes.
5143 bool bdrv_supports_compressed_writes(BlockDriverState *bs)
5145 BlockDriverState *filtered;
5147 if (!bs->drv || !block_driver_can_compress(bs->drv)) {
5151 filtered = bdrv_filter_bs(bs);
5154 * Filters can only forward compressed writes, so we have to
5157 return bdrv_supports_compressed_writes(filtered);
5163 const char *bdrv_get_format_name(BlockDriverState *bs)
5165 return bs->drv ? bs->drv->format_name : NULL;
5168 static int qsort_strcmp(const void *a, const void *b)
5170 return strcmp(*(char *const *)a, *(char *const *)b);
5173 void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
5174 void *opaque, bool read_only)
5179 const char **formats = NULL;
5181 QLIST_FOREACH(drv, &bdrv_drivers, list) {
5182 if (drv->format_name) {
5186 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) {
5190 while (formats && i && !found) {
5191 found = !strcmp(formats[--i], drv->format_name);
5195 formats = g_renew(const char *, formats, count + 1);
5196 formats[count++] = drv->format_name;
5201 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) {
5202 const char *format_name = block_driver_modules[i].format_name;
5208 if (use_bdrv_whitelist &&
5209 !bdrv_format_is_whitelisted(format_name, read_only)) {
5213 while (formats && j && !found) {
5214 found = !strcmp(formats[--j], format_name);
5218 formats = g_renew(const char *, formats, count + 1);
5219 formats[count++] = format_name;
5224 qsort(formats, count, sizeof(formats[0]), qsort_strcmp);
5226 for (i = 0; i < count; i++) {
5227 it(opaque, formats[i]);
5233 /* This function is to find a node in the bs graph */
5234 BlockDriverState *bdrv_find_node(const char *node_name)
5236 BlockDriverState *bs;
5240 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5241 if (!strcmp(node_name, bs->node_name)) {
5248 /* Put this QMP function here so it can access the static graph_bdrv_states. */
5249 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
5252 BlockDeviceInfoList *list;
5253 BlockDriverState *bs;
5256 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5257 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
5259 qapi_free_BlockDeviceInfoList(list);
5262 QAPI_LIST_PREPEND(list, info);
5268 typedef struct XDbgBlockGraphConstructor {
5269 XDbgBlockGraph *graph;
5270 GHashTable *graph_nodes;
5271 } XDbgBlockGraphConstructor;
5273 static XDbgBlockGraphConstructor *xdbg_graph_new(void)
5275 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1);
5277 gr->graph = g_new0(XDbgBlockGraph, 1);
5278 gr->graph_nodes = g_hash_table_new(NULL, NULL);
5283 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr)
5285 XDbgBlockGraph *graph = gr->graph;
5287 g_hash_table_destroy(gr->graph_nodes);
5293 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node)
5295 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node);
5302 * Start counting from 1, not 0, because 0 interferes with not-found (NULL)
5303 * answer of g_hash_table_lookup.
5305 ret = g_hash_table_size(gr->graph_nodes) + 1;
5306 g_hash_table_insert(gr->graph_nodes, node, (void *)ret);
5311 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node,
5312 XDbgBlockGraphNodeType type, const char *name)
5314 XDbgBlockGraphNode *n;
5316 n = g_new0(XDbgBlockGraphNode, 1);
5318 n->id = xdbg_graph_node_num(gr, node);
5320 n->name = g_strdup(name);
5322 QAPI_LIST_PREPEND(gr->graph->nodes, n);
5325 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent,
5326 const BdrvChild *child)
5328 BlockPermission qapi_perm;
5329 XDbgBlockGraphEdge *edge;
5331 edge = g_new0(XDbgBlockGraphEdge, 1);
5333 edge->parent = xdbg_graph_node_num(gr, parent);
5334 edge->child = xdbg_graph_node_num(gr, child->bs);
5335 edge->name = g_strdup(child->name);
5337 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) {
5338 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm);
5340 if (flag & child->perm) {
5341 QAPI_LIST_PREPEND(edge->perm, qapi_perm);
5343 if (flag & child->shared_perm) {
5344 QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm);
5348 QAPI_LIST_PREPEND(gr->graph->edges, edge);
5352 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp)
5356 BlockDriverState *bs;
5358 XDbgBlockGraphConstructor *gr = xdbg_graph_new();
5360 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
5361 char *allocated_name = NULL;
5362 const char *name = blk_name(blk);
5365 name = allocated_name = blk_get_attached_dev_id(blk);
5367 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND,
5369 g_free(allocated_name);
5370 if (blk_root(blk)) {
5371 xdbg_graph_add_edge(gr, blk, blk_root(blk));
5375 for (job = block_job_next(NULL); job; job = block_job_next(job)) {
5378 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB,
5380 for (el = job->nodes; el; el = el->next) {
5381 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data);
5385 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
5386 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER,
5388 QLIST_FOREACH(child, &bs->children, next) {
5389 xdbg_graph_add_edge(gr, bs, child);
5393 return xdbg_graph_finalize(gr);
5396 BlockDriverState *bdrv_lookup_bs(const char *device,
5397 const char *node_name,
5401 BlockDriverState *bs;
5404 blk = blk_by_name(device);
5409 error_setg(errp, "Device '%s' has no medium", device);
5417 bs = bdrv_find_node(node_name);
5424 error_setg(errp, "Cannot find device=%s nor node_name=%s",
5425 device ? device : "",
5426 node_name ? node_name : "");
5430 /* If 'base' is in the same chain as 'top', return true. Otherwise,
5431 * return false. If either argument is NULL, return false. */
5432 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
5434 while (top && top != base) {
5435 top = bdrv_filter_or_cow_bs(top);
5441 BlockDriverState *bdrv_next_node(BlockDriverState *bs)
5444 return QTAILQ_FIRST(&graph_bdrv_states);
5446 return QTAILQ_NEXT(bs, node_list);
5449 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs)
5452 return QTAILQ_FIRST(&all_bdrv_states);
5454 return QTAILQ_NEXT(bs, bs_list);
5457 const char *bdrv_get_node_name(const BlockDriverState *bs)
5459 return bs->node_name;
5462 const char *bdrv_get_parent_name(const BlockDriverState *bs)
5467 /* If multiple parents have a name, just pick the first one. */
5468 QLIST_FOREACH(c, &bs->parents, next_parent) {
5469 if (c->klass->get_name) {
5470 name = c->klass->get_name(c);
5471 if (name && *name) {
5480 /* TODO check what callers really want: bs->node_name or blk_name() */
5481 const char *bdrv_get_device_name(const BlockDriverState *bs)
5483 return bdrv_get_parent_name(bs) ?: "";
5486 /* This can be used to identify nodes that might not have a device
5487 * name associated. Since node and device names live in the same
5488 * namespace, the result is unambiguous. The exception is if both are
5489 * absent, then this returns an empty (non-null) string. */
5490 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
5492 return bdrv_get_parent_name(bs) ?: bs->node_name;
5495 int bdrv_get_flags(BlockDriverState *bs)
5497 return bs->open_flags;
5500 int bdrv_has_zero_init_1(BlockDriverState *bs)
5505 int bdrv_has_zero_init(BlockDriverState *bs)
5507 BlockDriverState *filtered;
5513 /* If BS is a copy on write image, it is initialized to
5514 the contents of the base image, which may not be zeroes. */
5515 if (bdrv_cow_child(bs)) {
5518 if (bs->drv->bdrv_has_zero_init) {
5519 return bs->drv->bdrv_has_zero_init(bs);
5522 filtered = bdrv_filter_bs(bs);
5524 return bdrv_has_zero_init(filtered);
5531 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
5533 if (!(bs->open_flags & BDRV_O_UNMAP)) {
5537 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
5540 void bdrv_get_backing_filename(BlockDriverState *bs,
5541 char *filename, int filename_size)
5543 pstrcpy(filename, filename_size, bs->backing_file);
5546 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
5549 BlockDriver *drv = bs->drv;
5550 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
5554 if (!drv->bdrv_get_info) {
5555 BlockDriverState *filtered = bdrv_filter_bs(bs);
5557 return bdrv_get_info(filtered, bdi);
5561 memset(bdi, 0, sizeof(*bdi));
5562 ret = drv->bdrv_get_info(bs, bdi);
5567 if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) {
5574 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
5577 BlockDriver *drv = bs->drv;
5578 if (drv && drv->bdrv_get_specific_info) {
5579 return drv->bdrv_get_specific_info(bs, errp);
5584 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs)
5586 BlockDriver *drv = bs->drv;
5587 if (!drv || !drv->bdrv_get_specific_stats) {
5590 return drv->bdrv_get_specific_stats(bs);
5593 void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event)
5595 if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) {
5599 bs->drv->bdrv_debug_event(bs, event);
5602 static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs)
5604 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
5605 bs = bdrv_primary_bs(bs);
5608 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
5609 assert(bs->drv->bdrv_debug_remove_breakpoint);
5616 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event,
5619 bs = bdrv_find_debug_node(bs);
5621 return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
5627 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
5629 bs = bdrv_find_debug_node(bs);
5631 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
5637 int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
5639 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
5640 bs = bdrv_primary_bs(bs);
5643 if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
5644 return bs->drv->bdrv_debug_resume(bs, tag);
5650 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
5652 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
5653 bs = bdrv_primary_bs(bs);
5656 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
5657 return bs->drv->bdrv_debug_is_suspended(bs, tag);
5663 /* backing_file can either be relative, or absolute, or a protocol. If it is
5664 * relative, it must be relative to the chain. So, passing in bs->filename
5665 * from a BDS as backing_file should not be done, as that may be relative to
5666 * the CWD rather than the chain. */
5667 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
5668 const char *backing_file)
5670 char *filename_full = NULL;
5671 char *backing_file_full = NULL;
5672 char *filename_tmp = NULL;
5673 int is_protocol = 0;
5674 bool filenames_refreshed = false;
5675 BlockDriverState *curr_bs = NULL;
5676 BlockDriverState *retval = NULL;
5677 BlockDriverState *bs_below;
5679 if (!bs || !bs->drv || !backing_file) {
5683 filename_full = g_malloc(PATH_MAX);
5684 backing_file_full = g_malloc(PATH_MAX);
5686 is_protocol = path_has_protocol(backing_file);
5689 * Being largely a legacy function, skip any filters here
5690 * (because filters do not have normal filenames, so they cannot
5691 * match anyway; and allowing json:{} filenames is a bit out of
5694 for (curr_bs = bdrv_skip_filters(bs);
5695 bdrv_cow_child(curr_bs) != NULL;
5698 bs_below = bdrv_backing_chain_next(curr_bs);
5700 if (bdrv_backing_overridden(curr_bs)) {
5702 * If the backing file was overridden, we can only compare
5703 * directly against the backing node's filename.
5706 if (!filenames_refreshed) {
5708 * This will automatically refresh all of the
5709 * filenames in the rest of the backing chain, so we
5710 * only need to do this once.
5712 bdrv_refresh_filename(bs_below);
5713 filenames_refreshed = true;
5716 if (strcmp(backing_file, bs_below->filename) == 0) {
5720 } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
5722 * If either of the filename paths is actually a protocol, then
5723 * compare unmodified paths; otherwise make paths relative.
5725 char *backing_file_full_ret;
5727 if (strcmp(backing_file, curr_bs->backing_file) == 0) {
5731 /* Also check against the full backing filename for the image */
5732 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs,
5734 if (backing_file_full_ret) {
5735 bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
5736 g_free(backing_file_full_ret);
5743 /* If not an absolute filename path, make it relative to the current
5744 * image's filename path */
5745 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
5747 /* We are going to compare canonicalized absolute pathnames */
5748 if (!filename_tmp || !realpath(filename_tmp, filename_full)) {
5749 g_free(filename_tmp);
5752 g_free(filename_tmp);
5754 /* We need to make sure the backing filename we are comparing against
5755 * is relative to the current image filename (or absolute) */
5756 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
5757 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) {
5758 g_free(filename_tmp);
5761 g_free(filename_tmp);
5763 if (strcmp(backing_file_full, filename_full) == 0) {
5770 g_free(filename_full);
5771 g_free(backing_file_full);
5775 void bdrv_init(void)
5777 module_call_init(MODULE_INIT_BLOCK);
5780 void bdrv_init_with_whitelist(void)
5782 use_bdrv_whitelist = 1;
5786 int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp)
5788 BdrvChild *child, *parent;
5789 Error *local_err = NULL;
5791 BdrvDirtyBitmap *bm;
5797 QLIST_FOREACH(child, &bs->children, next) {
5798 bdrv_co_invalidate_cache(child->bs, &local_err);
5800 error_propagate(errp, local_err);
5806 * Update permissions, they may differ for inactive nodes.
5808 * Note that the required permissions of inactive images are always a
5809 * subset of the permissions required after activating the image. This
5810 * allows us to just get the permissions upfront without restricting
5811 * drv->bdrv_invalidate_cache().
5813 * It also means that in error cases, we don't have to try and revert to
5814 * the old permissions (which is an operation that could fail, too). We can
5815 * just keep the extended permissions for the next time that an activation
5816 * of the image is tried.
5818 if (bs->open_flags & BDRV_O_INACTIVE) {
5819 bs->open_flags &= ~BDRV_O_INACTIVE;
5820 ret = bdrv_refresh_perms(bs, NULL, errp);
5822 bs->open_flags |= BDRV_O_INACTIVE;
5826 if (bs->drv->bdrv_co_invalidate_cache) {
5827 bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
5829 bs->open_flags |= BDRV_O_INACTIVE;
5830 error_propagate(errp, local_err);
5835 FOR_EACH_DIRTY_BITMAP(bs, bm) {
5836 bdrv_dirty_bitmap_skip_store(bm, false);
5839 ret = refresh_total_sectors(bs, bs->total_sectors);
5841 bs->open_flags |= BDRV_O_INACTIVE;
5842 error_setg_errno(errp, -ret, "Could not refresh total sector count");
5847 QLIST_FOREACH(parent, &bs->parents, next_parent) {
5848 if (parent->klass->activate) {
5849 parent->klass->activate(parent, &local_err);
5851 bs->open_flags |= BDRV_O_INACTIVE;
5852 error_propagate(errp, local_err);
5861 void bdrv_invalidate_cache_all(Error **errp)
5863 BlockDriverState *bs;
5864 BdrvNextIterator it;
5866 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
5867 AioContext *aio_context = bdrv_get_aio_context(bs);
5870 aio_context_acquire(aio_context);
5871 ret = bdrv_invalidate_cache(bs, errp);
5872 aio_context_release(aio_context);
5874 bdrv_next_cleanup(&it);
5880 static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
5884 QLIST_FOREACH(parent, &bs->parents, next_parent) {
5885 if (parent->klass->parent_is_bds) {
5886 BlockDriverState *parent_bs = parent->opaque;
5887 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) {
5896 static int bdrv_inactivate_recurse(BlockDriverState *bs)
5898 BdrvChild *child, *parent;
5899 bool tighten_restrictions;
5906 /* Make sure that we don't inactivate a child before its parent.
5907 * It will be covered by recursion from the yet active parent. */
5908 if (bdrv_has_bds_parent(bs, true)) {
5912 assert(!(bs->open_flags & BDRV_O_INACTIVE));
5914 /* Inactivate this node */
5915 if (bs->drv->bdrv_inactivate) {
5916 ret = bs->drv->bdrv_inactivate(bs);
5922 QLIST_FOREACH(parent, &bs->parents, next_parent) {
5923 if (parent->klass->inactivate) {
5924 ret = parent->klass->inactivate(parent);
5931 bs->open_flags |= BDRV_O_INACTIVE;
5934 * Update permissions, they may differ for inactive nodes.
5935 * We only tried to loosen restrictions, so errors are not fatal, ignore
5938 bdrv_refresh_perms(bs, &tighten_restrictions, NULL);
5939 assert(tighten_restrictions == false);
5941 /* Recursively inactivate children */
5942 QLIST_FOREACH(child, &bs->children, next) {
5943 ret = bdrv_inactivate_recurse(child->bs);
5952 int bdrv_inactivate_all(void)
5954 BlockDriverState *bs = NULL;
5955 BdrvNextIterator it;
5957 GSList *aio_ctxs = NULL, *ctx;
5959 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
5960 AioContext *aio_context = bdrv_get_aio_context(bs);
5962 if (!g_slist_find(aio_ctxs, aio_context)) {
5963 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
5964 aio_context_acquire(aio_context);
5968 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
5969 /* Nodes with BDS parents are covered by recursion from the last
5970 * parent that gets inactivated. Don't inactivate them a second
5971 * time if that has already happened. */
5972 if (bdrv_has_bds_parent(bs, false)) {
5975 ret = bdrv_inactivate_recurse(bs);
5977 bdrv_next_cleanup(&it);
5983 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
5984 AioContext *aio_context = ctx->data;
5985 aio_context_release(aio_context);
5987 g_slist_free(aio_ctxs);
5992 /**************************************************************/
5993 /* removable device support */
5996 * Return TRUE if the media is present
5998 bool bdrv_is_inserted(BlockDriverState *bs)
6000 BlockDriver *drv = bs->drv;
6006 if (drv->bdrv_is_inserted) {
6007 return drv->bdrv_is_inserted(bs);
6009 QLIST_FOREACH(child, &bs->children, next) {
6010 if (!bdrv_is_inserted(child->bs)) {
6018 * If eject_flag is TRUE, eject the media. Otherwise, close the tray
6020 void bdrv_eject(BlockDriverState *bs, bool eject_flag)
6022 BlockDriver *drv = bs->drv;
6024 if (drv && drv->bdrv_eject) {
6025 drv->bdrv_eject(bs, eject_flag);
6030 * Lock or unlock the media (if it is locked, the user won't be able
6031 * to eject it manually).
6033 void bdrv_lock_medium(BlockDriverState *bs, bool locked)
6035 BlockDriver *drv = bs->drv;
6037 trace_bdrv_lock_medium(bs, locked);
6039 if (drv && drv->bdrv_lock_medium) {
6040 drv->bdrv_lock_medium(bs, locked);
6044 /* Get a reference to bs */
6045 void bdrv_ref(BlockDriverState *bs)
6050 /* Release a previously grabbed reference to bs.
6051 * If after releasing, reference count is zero, the BlockDriverState is
6053 void bdrv_unref(BlockDriverState *bs)
6058 assert(bs->refcnt > 0);
6059 if (--bs->refcnt == 0) {
6064 struct BdrvOpBlocker {
6066 QLIST_ENTRY(BdrvOpBlocker) list;
6069 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
6071 BdrvOpBlocker *blocker;
6072 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6073 if (!QLIST_EMPTY(&bs->op_blockers[op])) {
6074 blocker = QLIST_FIRST(&bs->op_blockers[op]);
6075 error_propagate_prepend(errp, error_copy(blocker->reason),
6076 "Node '%s' is busy: ",
6077 bdrv_get_device_or_node_name(bs));
6083 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
6085 BdrvOpBlocker *blocker;
6086 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6088 blocker = g_new0(BdrvOpBlocker, 1);
6089 blocker->reason = reason;
6090 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
6093 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
6095 BdrvOpBlocker *blocker, *next;
6096 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
6097 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
6098 if (blocker->reason == reason) {
6099 QLIST_REMOVE(blocker, list);
6105 void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
6108 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6109 bdrv_op_block(bs, i, reason);
6113 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
6116 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6117 bdrv_op_unblock(bs, i, reason);
6121 bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
6125 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
6126 if (!QLIST_EMPTY(&bs->op_blockers[i])) {
6133 void bdrv_img_create(const char *filename, const char *fmt,
6134 const char *base_filename, const char *base_fmt,
6135 char *options, uint64_t img_size, int flags, bool quiet,
6138 QemuOptsList *create_opts = NULL;
6139 QemuOpts *opts = NULL;
6140 const char *backing_fmt, *backing_file;
6142 BlockDriver *drv, *proto_drv;
6143 Error *local_err = NULL;
6146 /* Find driver and parse its options */
6147 drv = bdrv_find_format(fmt);
6149 error_setg(errp, "Unknown file format '%s'", fmt);
6153 proto_drv = bdrv_find_protocol(filename, true, errp);
6158 if (!drv->create_opts) {
6159 error_setg(errp, "Format driver '%s' does not support image creation",
6164 if (!proto_drv->create_opts) {
6165 error_setg(errp, "Protocol driver '%s' does not support image creation",
6166 proto_drv->format_name);
6170 /* Create parameter list */
6171 create_opts = qemu_opts_append(create_opts, drv->create_opts);
6172 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
6174 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
6176 /* Parse -o options */
6178 if (!qemu_opts_do_parse(opts, options, NULL, errp)) {
6183 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) {
6184 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort);
6185 } else if (img_size != UINT64_C(-1)) {
6186 error_setg(errp, "The image size must be specified only once");
6190 if (base_filename) {
6191 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename,
6193 error_setg(errp, "Backing file not supported for file format '%s'",
6200 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) {
6201 error_setg(errp, "Backing file format not supported for file "
6202 "format '%s'", fmt);
6207 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
6209 if (!strcmp(filename, backing_file)) {
6210 error_setg(errp, "Error: Trying to create an image with the "
6211 "same filename as the backing file");
6214 if (backing_file[0] == '\0') {
6215 error_setg(errp, "Expected backing file name, got empty string");
6220 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
6222 /* The size for the image must always be specified, unless we have a backing
6223 * file and we have not been forbidden from opening it. */
6224 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
6225 if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
6226 BlockDriverState *bs;
6229 QDict *backing_options = NULL;
6232 bdrv_get_full_backing_filename_from_filename(filename, backing_file,
6237 assert(full_backing);
6239 /* backing files always opened read-only */
6241 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
6243 backing_options = qdict_new();
6245 qdict_put_str(backing_options, "driver", backing_fmt);
6247 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
6249 bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
6251 g_free(full_backing);
6253 error_append_hint(&local_err, "Could not open backing image.\n");
6257 warn_report("Deprecated use of backing file without explicit "
6258 "backing format (detected format of %s)",
6259 bs->drv->format_name);
6260 if (bs->drv != &bdrv_raw) {
6262 * A probe of raw deserves the most attention:
6263 * leaving the backing format out of the image
6264 * will ensure bs->probed is set (ensuring we
6265 * don't accidentally commit into the backing
6266 * file), and allow more spots to warn the users
6267 * to fix their toolchain when opening this image
6268 * later. For other images, we can safely record
6269 * the format that we probed.
6271 backing_fmt = bs->drv->format_name;
6272 qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, backing_fmt,
6277 /* Opened BS, have no size */
6278 size = bdrv_getlength(bs);
6280 error_setg_errno(errp, -size, "Could not get size of '%s'",
6285 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
6289 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
6290 } else if (backing_file && !backing_fmt) {
6291 warn_report("Deprecated use of unopened backing file without "
6292 "explicit backing format, use of this image requires "
6293 "potentially unsafe format probing");
6297 error_setg(errp, "Image creation needs a size parameter");
6302 printf("Formatting '%s', fmt=%s ", filename, fmt);
6303 qemu_opts_print(opts, " ");
6308 ret = bdrv_create(drv, filename, opts, &local_err);
6310 if (ret == -EFBIG) {
6311 /* This is generally a better message than whatever the driver would
6312 * deliver (especially because of the cluster_size_hint), since that
6313 * is most probably not much different from "image too large". */
6314 const char *cluster_size_hint = "";
6315 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) {
6316 cluster_size_hint = " (try using a larger cluster size)";
6318 error_setg(errp, "The image size is too large for file format '%s'"
6319 "%s", fmt, cluster_size_hint);
6320 error_free(local_err);
6325 qemu_opts_del(opts);
6326 qemu_opts_free(create_opts);
6327 error_propagate(errp, local_err);
6330 AioContext *bdrv_get_aio_context(BlockDriverState *bs)
6332 return bs ? bs->aio_context : qemu_get_aio_context();
6335 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs)
6337 Coroutine *self = qemu_coroutine_self();
6338 AioContext *old_ctx = qemu_coroutine_get_aio_context(self);
6339 AioContext *new_ctx;
6342 * Increase bs->in_flight to ensure that this operation is completed before
6343 * moving the node to a different AioContext. Read new_ctx only afterwards.
6345 bdrv_inc_in_flight(bs);
6347 new_ctx = bdrv_get_aio_context(bs);
6348 aio_co_reschedule_self(new_ctx);
6352 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx)
6354 aio_co_reschedule_self(old_ctx);
6355 bdrv_dec_in_flight(bs);
6358 void coroutine_fn bdrv_co_lock(BlockDriverState *bs)
6360 AioContext *ctx = bdrv_get_aio_context(bs);
6362 /* In the main thread, bs->aio_context won't change concurrently */
6363 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
6366 * We're in coroutine context, so we already hold the lock of the main
6367 * loop AioContext. Don't lock it twice to avoid deadlocks.
6369 assert(qemu_in_coroutine());
6370 if (ctx != qemu_get_aio_context()) {
6371 aio_context_acquire(ctx);
6375 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs)
6377 AioContext *ctx = bdrv_get_aio_context(bs);
6379 assert(qemu_in_coroutine());
6380 if (ctx != qemu_get_aio_context()) {
6381 aio_context_release(ctx);
6385 void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co)
6387 aio_co_enter(bdrv_get_aio_context(bs), co);
6390 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
6392 QLIST_REMOVE(ban, list);
6396 static void bdrv_detach_aio_context(BlockDriverState *bs)
6398 BdrvAioNotifier *baf, *baf_tmp;
6400 assert(!bs->walking_aio_notifiers);
6401 bs->walking_aio_notifiers = true;
6402 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
6404 bdrv_do_remove_aio_context_notifier(baf);
6406 baf->detach_aio_context(baf->opaque);
6409 /* Never mind iterating again to check for ->deleted. bdrv_close() will
6410 * remove remaining aio notifiers if we aren't called again.
6412 bs->walking_aio_notifiers = false;
6414 if (bs->drv && bs->drv->bdrv_detach_aio_context) {
6415 bs->drv->bdrv_detach_aio_context(bs);
6418 if (bs->quiesce_counter) {
6419 aio_enable_external(bs->aio_context);
6421 bs->aio_context = NULL;
6424 static void bdrv_attach_aio_context(BlockDriverState *bs,
6425 AioContext *new_context)
6427 BdrvAioNotifier *ban, *ban_tmp;
6429 if (bs->quiesce_counter) {
6430 aio_disable_external(new_context);
6433 bs->aio_context = new_context;
6435 if (bs->drv && bs->drv->bdrv_attach_aio_context) {
6436 bs->drv->bdrv_attach_aio_context(bs, new_context);
6439 assert(!bs->walking_aio_notifiers);
6440 bs->walking_aio_notifiers = true;
6441 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) {
6443 bdrv_do_remove_aio_context_notifier(ban);
6445 ban->attached_aio_context(new_context, ban->opaque);
6448 bs->walking_aio_notifiers = false;
6452 * Changes the AioContext used for fd handlers, timers, and BHs by this
6453 * BlockDriverState and all its children and parents.
6455 * Must be called from the main AioContext.
6457 * The caller must own the AioContext lock for the old AioContext of bs, but it
6458 * must not own the AioContext lock for new_context (unless new_context is the
6459 * same as the current context of bs).
6461 * @ignore will accumulate all visited BdrvChild object. The caller is
6462 * responsible for freeing the list afterwards.
6464 void bdrv_set_aio_context_ignore(BlockDriverState *bs,
6465 AioContext *new_context, GSList **ignore)
6467 AioContext *old_context = bdrv_get_aio_context(bs);
6470 g_assert(qemu_get_current_aio_context() == qemu_get_aio_context());
6472 if (old_context == new_context) {
6476 bdrv_drained_begin(bs);
6478 QLIST_FOREACH(child, &bs->children, next) {
6479 if (g_slist_find(*ignore, child)) {
6482 *ignore = g_slist_prepend(*ignore, child);
6483 bdrv_set_aio_context_ignore(child->bs, new_context, ignore);
6485 QLIST_FOREACH(child, &bs->parents, next_parent) {
6486 if (g_slist_find(*ignore, child)) {
6489 assert(child->klass->set_aio_ctx);
6490 *ignore = g_slist_prepend(*ignore, child);
6491 child->klass->set_aio_ctx(child, new_context, ignore);
6494 bdrv_detach_aio_context(bs);
6496 /* Acquire the new context, if necessary */
6497 if (qemu_get_aio_context() != new_context) {
6498 aio_context_acquire(new_context);
6501 bdrv_attach_aio_context(bs, new_context);
6504 * If this function was recursively called from
6505 * bdrv_set_aio_context_ignore(), there may be nodes in the
6506 * subtree that have not yet been moved to the new AioContext.
6507 * Release the old one so bdrv_drained_end() can poll them.
6509 if (qemu_get_aio_context() != old_context) {
6510 aio_context_release(old_context);
6513 bdrv_drained_end(bs);
6515 if (qemu_get_aio_context() != old_context) {
6516 aio_context_acquire(old_context);
6518 if (qemu_get_aio_context() != new_context) {
6519 aio_context_release(new_context);
6523 static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx,
6524 GSList **ignore, Error **errp)
6526 if (g_slist_find(*ignore, c)) {
6529 *ignore = g_slist_prepend(*ignore, c);
6532 * A BdrvChildClass that doesn't handle AioContext changes cannot
6533 * tolerate any AioContext changes
6535 if (!c->klass->can_set_aio_ctx) {
6536 char *user = bdrv_child_user_desc(c);
6537 error_setg(errp, "Changing iothreads is not supported by %s", user);
6541 if (!c->klass->can_set_aio_ctx(c, ctx, ignore, errp)) {
6542 assert(!errp || *errp);
6548 bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
6549 GSList **ignore, Error **errp)
6551 if (g_slist_find(*ignore, c)) {
6554 *ignore = g_slist_prepend(*ignore, c);
6555 return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp);
6558 /* @ignore will accumulate all visited BdrvChild object. The caller is
6559 * responsible for freeing the list afterwards. */
6560 bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
6561 GSList **ignore, Error **errp)
6565 if (bdrv_get_aio_context(bs) == ctx) {
6569 QLIST_FOREACH(c, &bs->parents, next_parent) {
6570 if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) {
6574 QLIST_FOREACH(c, &bs->children, next) {
6575 if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) {
6583 int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
6584 BdrvChild *ignore_child, Error **errp)
6589 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
6590 ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp);
6591 g_slist_free(ignore);
6597 ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
6598 bdrv_set_aio_context_ignore(bs, ctx, &ignore);
6599 g_slist_free(ignore);
6604 int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
6607 return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp);
6610 void bdrv_add_aio_context_notifier(BlockDriverState *bs,
6611 void (*attached_aio_context)(AioContext *new_context, void *opaque),
6612 void (*detach_aio_context)(void *opaque), void *opaque)
6614 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1);
6615 *ban = (BdrvAioNotifier){
6616 .attached_aio_context = attached_aio_context,
6617 .detach_aio_context = detach_aio_context,
6621 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list);
6624 void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
6625 void (*attached_aio_context)(AioContext *,
6627 void (*detach_aio_context)(void *),
6630 BdrvAioNotifier *ban, *ban_next;
6632 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
6633 if (ban->attached_aio_context == attached_aio_context &&
6634 ban->detach_aio_context == detach_aio_context &&
6635 ban->opaque == opaque &&
6636 ban->deleted == false)
6638 if (bs->walking_aio_notifiers) {
6639 ban->deleted = true;
6641 bdrv_do_remove_aio_context_notifier(ban);
6650 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
6651 BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
6656 error_setg(errp, "Node is ejected");
6659 if (!bs->drv->bdrv_amend_options) {
6660 error_setg(errp, "Block driver '%s' does not support option amendment",
6661 bs->drv->format_name);
6664 return bs->drv->bdrv_amend_options(bs, opts, status_cb,
6665 cb_opaque, force, errp);
6669 * This function checks whether the given @to_replace is allowed to be
6670 * replaced by a node that always shows the same data as @bs. This is
6671 * used for example to verify whether the mirror job can replace
6672 * @to_replace by the target mirrored from @bs.
6673 * To be replaceable, @bs and @to_replace may either be guaranteed to
6674 * always show the same data (because they are only connected through
6675 * filters), or some driver may allow replacing one of its children
6676 * because it can guarantee that this child's data is not visible at
6677 * all (for example, for dissenting quorum children that have no other
6680 bool bdrv_recurse_can_replace(BlockDriverState *bs,
6681 BlockDriverState *to_replace)
6683 BlockDriverState *filtered;
6685 if (!bs || !bs->drv) {
6689 if (bs == to_replace) {
6693 /* See what the driver can do */
6694 if (bs->drv->bdrv_recurse_can_replace) {
6695 return bs->drv->bdrv_recurse_can_replace(bs, to_replace);
6698 /* For filters without an own implementation, we can recurse on our own */
6699 filtered = bdrv_filter_bs(bs);
6701 return bdrv_recurse_can_replace(filtered, to_replace);
6709 * Check whether the given @node_name can be replaced by a node that
6710 * has the same data as @parent_bs. If so, return @node_name's BDS;
6713 * @node_name must be a (recursive) *child of @parent_bs (or this
6714 * function will return NULL).
6716 * The result (whether the node can be replaced or not) is only valid
6717 * for as long as no graph or permission changes occur.
6719 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
6720 const char *node_name, Error **errp)
6722 BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
6723 AioContext *aio_context;
6725 if (!to_replace_bs) {
6726 error_setg(errp, "Node name '%s' not found", node_name);
6730 aio_context = bdrv_get_aio_context(to_replace_bs);
6731 aio_context_acquire(aio_context);
6733 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
6734 to_replace_bs = NULL;
6738 /* We don't want arbitrary node of the BDS chain to be replaced only the top
6739 * most non filter in order to prevent data corruption.
6740 * Another benefit is that this tests exclude backing files which are
6741 * blocked by the backing blockers.
6743 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) {
6744 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', "
6745 "because it cannot be guaranteed that doing so would not "
6746 "lead to an abrupt change of visible data",
6747 node_name, parent_bs->node_name);
6748 to_replace_bs = NULL;
6753 aio_context_release(aio_context);
6754 return to_replace_bs;
6758 * Iterates through the list of runtime option keys that are said to
6759 * be "strong" for a BDS. An option is called "strong" if it changes
6760 * a BDS's data. For example, the null block driver's "size" and
6761 * "read-zeroes" options are strong, but its "latency-ns" option is
6764 * If a key returned by this function ends with a dot, all options
6765 * starting with that prefix are strong.
6767 static const char *const *strong_options(BlockDriverState *bs,
6768 const char *const *curopt)
6770 static const char *const global_options[] = {
6771 "driver", "filename", NULL
6775 return &global_options[0];
6779 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
6780 curopt = bs->drv->strong_runtime_opts;
6783 return (curopt && *curopt) ? curopt : NULL;
6787 * Copies all strong runtime options from bs->options to the given
6788 * QDict. The set of strong option keys is determined by invoking
6791 * Returns true iff any strong option was present in bs->options (and
6792 * thus copied to the target QDict) with the exception of "filename"
6793 * and "driver". The caller is expected to use this value to decide
6794 * whether the existence of strong options prevents the generation of
6797 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
6799 bool found_any = false;
6800 const char *const *option_name = NULL;
6806 while ((option_name = strong_options(bs, option_name))) {
6807 bool option_given = false;
6809 assert(strlen(*option_name) > 0);
6810 if ((*option_name)[strlen(*option_name) - 1] != '.') {
6811 QObject *entry = qdict_get(bs->options, *option_name);
6816 qdict_put_obj(d, *option_name, qobject_ref(entry));
6817 option_given = true;
6819 const QDictEntry *entry;
6820 for (entry = qdict_first(bs->options); entry;
6821 entry = qdict_next(bs->options, entry))
6823 if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
6824 qdict_put_obj(d, qdict_entry_key(entry),
6825 qobject_ref(qdict_entry_value(entry)));
6826 option_given = true;
6831 /* While "driver" and "filename" need to be included in a JSON filename,
6832 * their existence does not prohibit generation of a plain filename. */
6833 if (!found_any && option_given &&
6834 strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
6840 if (!qdict_haskey(d, "driver")) {
6841 /* Drivers created with bdrv_new_open_driver() may not have a
6842 * @driver option. Add it here. */
6843 qdict_put_str(d, "driver", bs->drv->format_name);
6849 /* Note: This function may return false positives; it may return true
6850 * even if opening the backing file specified by bs's image header
6851 * would result in exactly bs->backing. */
6852 bool bdrv_backing_overridden(BlockDriverState *bs)
6855 return strcmp(bs->auto_backing_file,
6856 bs->backing->bs->filename);
6858 /* No backing BDS, so if the image header reports any backing
6859 * file, it must have been suppressed */
6860 return bs->auto_backing_file[0] != '\0';
6864 /* Updates the following BDS fields:
6865 * - exact_filename: A filename which may be used for opening a block device
6866 * which (mostly) equals the given BDS (even without any
6867 * other options; so reading and writing must return the same
6868 * results, but caching etc. may be different)
6869 * - full_open_options: Options which, when given when opening a block device
6870 * (without a filename), result in a BDS (mostly)
6871 * equalling the given one
6872 * - filename: If exact_filename is set, it is copied here. Otherwise,
6873 * full_open_options is converted to a JSON object, prefixed with
6874 * "json:" (for use through the JSON pseudo protocol) and put here.
6876 void bdrv_refresh_filename(BlockDriverState *bs)
6878 BlockDriver *drv = bs->drv;
6880 BlockDriverState *primary_child_bs;
6882 bool backing_overridden;
6883 bool generate_json_filename; /* Whether our default implementation should
6884 fill exact_filename (false) or not (true) */
6890 /* This BDS's file name may depend on any of its children's file names, so
6891 * refresh those first */
6892 QLIST_FOREACH(child, &bs->children, next) {
6893 bdrv_refresh_filename(child->bs);
6897 /* For implicit nodes, just copy everything from the single child */
6898 child = QLIST_FIRST(&bs->children);
6899 assert(QLIST_NEXT(child, next) == NULL);
6901 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
6902 child->bs->exact_filename);
6903 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
6905 qobject_unref(bs->full_open_options);
6906 bs->full_open_options = qobject_ref(child->bs->full_open_options);
6911 backing_overridden = bdrv_backing_overridden(bs);
6913 if (bs->open_flags & BDRV_O_NO_IO) {
6914 /* Without I/O, the backing file does not change anything.
6915 * Therefore, in such a case (primarily qemu-img), we can
6916 * pretend the backing file has not been overridden even if
6917 * it technically has been. */
6918 backing_overridden = false;
6921 /* Gather the options QDict */
6923 generate_json_filename = append_strong_runtime_options(opts, bs);
6924 generate_json_filename |= backing_overridden;
6926 if (drv->bdrv_gather_child_options) {
6927 /* Some block drivers may not want to present all of their children's
6928 * options, or name them differently from BdrvChild.name */
6929 drv->bdrv_gather_child_options(bs, opts, backing_overridden);
6931 QLIST_FOREACH(child, &bs->children, next) {
6932 if (child == bs->backing && !backing_overridden) {
6933 /* We can skip the backing BDS if it has not been overridden */
6937 qdict_put(opts, child->name,
6938 qobject_ref(child->bs->full_open_options));
6941 if (backing_overridden && !bs->backing) {
6942 /* Force no backing file */
6943 qdict_put_null(opts, "backing");
6947 qobject_unref(bs->full_open_options);
6948 bs->full_open_options = opts;
6950 primary_child_bs = bdrv_primary_bs(bs);
6952 if (drv->bdrv_refresh_filename) {
6953 /* Obsolete information is of no use here, so drop the old file name
6954 * information before refreshing it */
6955 bs->exact_filename[0] = '\0';
6957 drv->bdrv_refresh_filename(bs);
6958 } else if (primary_child_bs) {
6960 * Try to reconstruct valid information from the underlying
6961 * file -- this only works for format nodes (filter nodes
6962 * cannot be probed and as such must be selected by the user
6963 * either through an options dict, or through a special
6964 * filename which the filter driver must construct in its
6965 * .bdrv_refresh_filename() implementation).
6968 bs->exact_filename[0] = '\0';
6971 * We can use the underlying file's filename if:
6972 * - it has a filename,
6973 * - the current BDS is not a filter,
6974 * - the file is a protocol BDS, and
6975 * - opening that file (as this BDS's format) will automatically create
6976 * the BDS tree we have right now, that is:
6977 * - the user did not significantly change this BDS's behavior with
6978 * some explicit (strong) options
6979 * - no non-file child of this BDS has been overridden by the user
6980 * Both of these conditions are represented by generate_json_filename.
6982 if (primary_child_bs->exact_filename[0] &&
6983 primary_child_bs->drv->bdrv_file_open &&
6984 !drv->is_filter && !generate_json_filename)
6986 strcpy(bs->exact_filename, primary_child_bs->exact_filename);
6990 if (bs->exact_filename[0]) {
6991 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
6993 QString *json = qobject_to_json(QOBJECT(bs->full_open_options));
6994 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s",
6995 qstring_get_str(json)) >= sizeof(bs->filename)) {
6996 /* Give user a hint if we truncated things. */
6997 strcpy(bs->filename + sizeof(bs->filename) - 4, "...");
6999 qobject_unref(json);
7003 char *bdrv_dirname(BlockDriverState *bs, Error **errp)
7005 BlockDriver *drv = bs->drv;
7006 BlockDriverState *child_bs;
7009 error_setg(errp, "Node '%s' is ejected", bs->node_name);
7013 if (drv->bdrv_dirname) {
7014 return drv->bdrv_dirname(bs, errp);
7017 child_bs = bdrv_primary_bs(bs);
7019 return bdrv_dirname(child_bs, errp);
7022 bdrv_refresh_filename(bs);
7023 if (bs->exact_filename[0] != '\0') {
7024 return path_combine(bs->exact_filename, "");
7027 error_setg(errp, "Cannot generate a base directory for %s nodes",
7033 * Hot add/remove a BDS's child. So the user can take a child offline when
7034 * it is broken and take a new child online
7036 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
7040 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
7041 error_setg(errp, "The node %s does not support adding a child",
7042 bdrv_get_device_or_node_name(parent_bs));
7046 if (!QLIST_EMPTY(&child_bs->parents)) {
7047 error_setg(errp, "The node %s already has a parent",
7048 child_bs->node_name);
7052 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
7055 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
7059 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
7060 error_setg(errp, "The node %s does not support removing a child",
7061 bdrv_get_device_or_node_name(parent_bs));
7065 QLIST_FOREACH(tmp, &parent_bs->children, next) {
7072 error_setg(errp, "The node %s does not have a child named %s",
7073 bdrv_get_device_or_node_name(parent_bs),
7074 bdrv_get_device_or_node_name(child->bs));
7078 parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
7081 int bdrv_make_empty(BdrvChild *c, Error **errp)
7083 BlockDriver *drv = c->bs->drv;
7086 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED));
7088 if (!drv->bdrv_make_empty) {
7089 error_setg(errp, "%s does not support emptying nodes",
7094 ret = drv->bdrv_make_empty(c->bs);
7096 error_setg_errno(errp, -ret, "Failed to empty %s",
7105 * Return the child that @bs acts as an overlay for, and from which data may be
7106 * copied in COW or COR operations. Usually this is the backing file.
7108 BdrvChild *bdrv_cow_child(BlockDriverState *bs)
7110 if (!bs || !bs->drv) {
7114 if (bs->drv->is_filter) {
7122 assert(bs->backing->role & BDRV_CHILD_COW);
7127 * If @bs acts as a filter for exactly one of its children, return
7130 BdrvChild *bdrv_filter_child(BlockDriverState *bs)
7134 if (!bs || !bs->drv) {
7138 if (!bs->drv->is_filter) {
7142 /* Only one of @backing or @file may be used */
7143 assert(!(bs->backing && bs->file));
7145 c = bs->backing ?: bs->file;
7150 assert(c->role & BDRV_CHILD_FILTERED);
7155 * Return either the result of bdrv_cow_child() or bdrv_filter_child(),
7156 * whichever is non-NULL.
7158 * Return NULL if both are NULL.
7160 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs)
7162 BdrvChild *cow_child = bdrv_cow_child(bs);
7163 BdrvChild *filter_child = bdrv_filter_child(bs);
7165 /* Filter nodes cannot have COW backing files */
7166 assert(!(cow_child && filter_child));
7168 return cow_child ?: filter_child;
7172 * Return the primary child of this node: For filters, that is the
7173 * filtered child. For other nodes, that is usually the child storing
7175 * (A generally more helpful description is that this is (usually) the
7176 * child that has the same filename as @bs.)
7178 * Drivers do not necessarily have a primary child; for example quorum
7181 BdrvChild *bdrv_primary_child(BlockDriverState *bs)
7183 BdrvChild *c, *found = NULL;
7185 QLIST_FOREACH(c, &bs->children, next) {
7186 if (c->role & BDRV_CHILD_PRIMARY) {
7195 static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs,
7196 bool stop_on_explicit_filter)
7204 while (!(stop_on_explicit_filter && !bs->implicit)) {
7205 c = bdrv_filter_child(bs);
7208 * A filter that is embedded in a working block graph must
7209 * have a child. Assert this here so this function does
7210 * not return a filter node that is not expected by the
7213 assert(!bs->drv || !bs->drv->is_filter);
7219 * Note that this treats nodes with bs->drv == NULL as not being
7220 * filters (bs->drv == NULL should be replaced by something else
7222 * The advantage of this behavior is that this function will thus
7223 * always return a non-NULL value (given a non-NULL @bs).
7230 * Return the first BDS that has not been added implicitly or that
7231 * does not have a filtered child down the chain starting from @bs
7232 * (including @bs itself).
7234 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
7236 return bdrv_do_skip_filters(bs, true);
7240 * Return the first BDS that does not have a filtered child down the
7241 * chain starting from @bs (including @bs itself).
7243 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
7245 return bdrv_do_skip_filters(bs, false);
7249 * For a backing chain, return the first non-filter backing image of
7250 * the first non-filter image.
7252 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
7254 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));