2 * QEMU System Emulator block driver
4 * Copyright (c) 2003 Fabrice Bellard
5 * Copyright (c) 2020 Virtuozzo International GmbH.
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
26 #include "qemu/osdep.h"
27 #include "block/trace.h"
28 #include "block/block_int.h"
29 #include "block/blockjob.h"
30 #include "block/dirty-bitmap.h"
31 #include "block/fuse.h"
32 #include "block/nbd.h"
33 #include "block/qdict.h"
34 #include "qemu/error-report.h"
35 #include "block/module_block.h"
36 #include "qemu/main-loop.h"
37 #include "qemu/module.h"
38 #include "qapi/error.h"
39 #include "qapi/qmp/qdict.h"
40 #include "qapi/qmp/qjson.h"
41 #include "qapi/qmp/qnull.h"
42 #include "qapi/qmp/qstring.h"
43 #include "qapi/qobject-output-visitor.h"
44 #include "qapi/qapi-visit-block-core.h"
45 #include "sysemu/block-backend.h"
46 #include "qemu/notify.h"
47 #include "qemu/option.h"
48 #include "qemu/coroutine.h"
49 #include "block/qapi.h"
50 #include "qemu/timer.h"
51 #include "qemu/cutils.h"
53 #include "qemu/range.h"
55 #include "block/coroutines.h"
58 #include <sys/ioctl.h>
59 #include <sys/queue.h>
60 #if defined(HAVE_SYS_DISK_H)
69 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
71 /* Protected by BQL */
72 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
73 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
75 /* Protected by BQL */
76 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
77 QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
79 /* Protected by BQL */
80 static QLIST_HEAD(, BlockDriver) bdrv_drivers =
81 QLIST_HEAD_INITIALIZER(bdrv_drivers);
83 static BlockDriverState *bdrv_open_inherit(const char *filename,
84 const char *reference,
85 QDict *options, int flags,
86 BlockDriverState *parent,
87 const BdrvChildClass *child_class,
88 BdrvChildRole child_role,
91 static bool bdrv_recurse_has_child(BlockDriverState *bs,
92 BlockDriverState *child);
94 static void bdrv_replace_child_noperm(BdrvChild *child,
95 BlockDriverState *new_bs);
96 static void bdrv_remove_child(BdrvChild *child, Transaction *tran);
98 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
99 BlockReopenQueue *queue,
100 Transaction *change_child_tran, Error **errp);
101 static void bdrv_reopen_commit(BDRVReopenState *reopen_state);
102 static void bdrv_reopen_abort(BDRVReopenState *reopen_state);
104 static bool bdrv_backing_overridden(BlockDriverState *bs);
106 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
107 GHashTable *visited, Transaction *tran,
110 /* If non-zero, use only whitelisted block drivers */
111 static int use_bdrv_whitelist;
114 static int is_windows_drive_prefix(const char *filename)
116 return (((filename[0] >= 'a' && filename[0] <= 'z') ||
117 (filename[0] >= 'A' && filename[0] <= 'Z')) &&
121 int is_windows_drive(const char *filename)
123 if (is_windows_drive_prefix(filename) &&
126 if (strstart(filename, "\\\\.\\", NULL) ||
127 strstart(filename, "//./", NULL))
133 size_t bdrv_opt_mem_align(BlockDriverState *bs)
135 if (!bs || !bs->drv) {
136 /* page size or 4k (hdd sector size) should be on the safe side */
137 return MAX(4096, qemu_real_host_page_size());
141 return bs->bl.opt_mem_alignment;
144 size_t bdrv_min_mem_align(BlockDriverState *bs)
146 if (!bs || !bs->drv) {
147 /* page size or 4k (hdd sector size) should be on the safe side */
148 return MAX(4096, qemu_real_host_page_size());
152 return bs->bl.min_mem_alignment;
155 /* check if the path starts with "<protocol>:" */
156 int path_has_protocol(const char *path)
161 if (is_windows_drive(path) ||
162 is_windows_drive_prefix(path)) {
165 p = path + strcspn(path, ":/\\");
167 p = path + strcspn(path, ":/");
173 int path_is_absolute(const char *path)
176 /* specific case for names like: "\\.\d:" */
177 if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
180 return (*path == '/' || *path == '\\');
182 return (*path == '/');
186 /* if filename is absolute, just return its duplicate. Otherwise, build a
187 path to it by considering it is relative to base_path. URL are
189 char *path_combine(const char *base_path, const char *filename)
191 const char *protocol_stripped = NULL;
196 if (path_is_absolute(filename)) {
197 return g_strdup(filename);
200 if (path_has_protocol(base_path)) {
201 protocol_stripped = strchr(base_path, ':');
202 if (protocol_stripped) {
206 p = protocol_stripped ?: base_path;
208 p1 = strrchr(base_path, '/');
212 p2 = strrchr(base_path, '\\');
213 if (!p1 || p2 > p1) {
228 result = g_malloc(len + strlen(filename) + 1);
229 memcpy(result, base_path, len);
230 strcpy(result + len, filename);
236 * Helper function for bdrv_parse_filename() implementations to remove optional
237 * protocol prefixes (especially "file:") from a filename and for putting the
238 * stripped filename into the options QDict if there is such a prefix.
240 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
243 if (strstart(filename, prefix, &filename)) {
244 /* Stripping the explicit protocol prefix may result in a protocol
245 * prefix being (wrongly) detected (if the filename contains a colon) */
246 if (path_has_protocol(filename)) {
247 GString *fat_filename;
249 /* This means there is some colon before the first slash; therefore,
250 * this cannot be an absolute path */
251 assert(!path_is_absolute(filename));
253 /* And we can thus fix the protocol detection issue by prefixing it
255 fat_filename = g_string_new("./");
256 g_string_append(fat_filename, filename);
258 assert(!path_has_protocol(fat_filename->str));
260 qdict_put(options, "filename",
261 qstring_from_gstring(fat_filename));
263 /* If no protocol prefix was detected, we can use the shortened
265 qdict_put_str(options, "filename", filename);
271 /* Returns whether the image file is opened as read-only. Note that this can
272 * return false and writing to the image file is still not possible because the
273 * image is inactivated. */
274 bool bdrv_is_read_only(BlockDriverState *bs)
277 return !(bs->open_flags & BDRV_O_RDWR);
280 static int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
281 bool ignore_allow_rdw, Error **errp)
285 /* Do not set read_only if copy_on_read is enabled */
286 if (bs->copy_on_read && read_only) {
287 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
288 bdrv_get_device_or_node_name(bs));
292 /* Do not clear read_only if it is prohibited */
293 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
296 error_setg(errp, "Node '%s' is read only",
297 bdrv_get_device_or_node_name(bs));
305 * Called by a driver that can only provide a read-only image.
307 * Returns 0 if the node is already read-only or it could switch the node to
308 * read-only because BDRV_O_AUTO_RDONLY is set.
310 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
311 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
312 * is not NULL, it is used as the error message for the Error object.
314 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
320 if (!(bs->open_flags & BDRV_O_RDWR)) {
323 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
327 ret = bdrv_can_set_read_only(bs, true, false, NULL);
332 bs->open_flags &= ~BDRV_O_RDWR;
337 error_setg(errp, "%s", errmsg ?: "Image is read-only");
342 * If @backing is empty, this function returns NULL without setting
343 * @errp. In all other cases, NULL will only be returned with @errp
346 * Therefore, a return value of NULL without @errp set means that
347 * there is no backing file; if @errp is set, there is one but its
348 * absolute filename cannot be generated.
350 char *bdrv_get_full_backing_filename_from_filename(const char *backed,
354 if (backing[0] == '\0') {
356 } else if (path_has_protocol(backing) || path_is_absolute(backing)) {
357 return g_strdup(backing);
358 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
359 error_setg(errp, "Cannot use relative backing file names for '%s'",
363 return path_combine(backed, backing);
368 * If @filename is empty or NULL, this function returns NULL without
369 * setting @errp. In all other cases, NULL will only be returned with
372 static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
373 const char *filename, Error **errp)
375 char *dir, *full_name;
377 if (!filename || filename[0] == '\0') {
379 } else if (path_has_protocol(filename) || path_is_absolute(filename)) {
380 return g_strdup(filename);
383 dir = bdrv_dirname(relative_to, errp);
388 full_name = g_strconcat(dir, filename, NULL);
393 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
396 return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
399 void bdrv_register(BlockDriver *bdrv)
401 assert(bdrv->format_name);
403 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
406 BlockDriverState *bdrv_new(void)
408 BlockDriverState *bs;
413 bs = g_new0(BlockDriverState, 1);
414 QLIST_INIT(&bs->dirty_bitmaps);
415 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
416 QLIST_INIT(&bs->op_blockers[i]);
418 qemu_co_mutex_init(&bs->reqs_lock);
419 qemu_mutex_init(&bs->dirty_bitmap_mutex);
421 bs->aio_context = qemu_get_aio_context();
423 qemu_co_queue_init(&bs->flush_queue);
425 qemu_co_mutex_init(&bs->bsc_modify_lock);
426 bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1);
428 for (i = 0; i < bdrv_drain_all_count; i++) {
429 bdrv_drained_begin(bs);
432 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
437 static BlockDriver *bdrv_do_find_format(const char *format_name)
442 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
443 if (!strcmp(drv1->format_name, format_name)) {
451 BlockDriver *bdrv_find_format(const char *format_name)
458 drv1 = bdrv_do_find_format(format_name);
463 /* The driver isn't registered, maybe we need to load a module */
464 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
465 if (!strcmp(block_driver_modules[i].format_name, format_name)) {
466 Error *local_err = NULL;
467 int rv = block_module_load(block_driver_modules[i].library_name,
470 return bdrv_do_find_format(format_name);
472 error_report_err(local_err);
480 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
482 static const char *whitelist_rw[] = {
483 CONFIG_BDRV_RW_WHITELIST
486 static const char *whitelist_ro[] = {
487 CONFIG_BDRV_RO_WHITELIST
492 if (!whitelist_rw[0] && !whitelist_ro[0]) {
493 return 1; /* no whitelist, anything goes */
496 for (p = whitelist_rw; *p; p++) {
497 if (!strcmp(format_name, *p)) {
502 for (p = whitelist_ro; *p; p++) {
503 if (!strcmp(format_name, *p)) {
511 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
514 return bdrv_format_is_whitelisted(drv->format_name, read_only);
517 bool bdrv_uses_whitelist(void)
519 return use_bdrv_whitelist;
522 typedef struct CreateCo {
530 int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename,
531 QemuOpts *opts, Error **errp)
537 if (!drv->bdrv_co_create_opts) {
538 error_setg(errp, "Driver '%s' does not support image creation",
543 ret = drv->bdrv_co_create_opts(drv, filename, opts, errp);
544 if (ret < 0 && !*errp) {
545 error_setg_errno(errp, -ret, "Could not create image");
552 * Helper function for bdrv_create_file_fallback(): Resize @blk to at
553 * least the given @minimum_size.
555 * On success, return @blk's actual length.
556 * Otherwise, return -errno.
558 static int64_t coroutine_fn GRAPH_UNLOCKED
559 create_file_fallback_truncate(BlockBackend *blk, int64_t minimum_size,
562 Error *local_err = NULL;
568 ret = blk_co_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0,
570 if (ret < 0 && ret != -ENOTSUP) {
571 error_propagate(errp, local_err);
575 size = blk_co_getlength(blk);
577 error_free(local_err);
578 error_setg_errno(errp, -size,
579 "Failed to inquire the new image file's length");
583 if (size < minimum_size) {
584 /* Need to grow the image, but we failed to do that */
585 error_propagate(errp, local_err);
589 error_free(local_err);
596 * Helper function for bdrv_create_file_fallback(): Zero the first
597 * sector to remove any potentially pre-existing image header.
599 static int coroutine_fn
600 create_file_fallback_zero_first_sector(BlockBackend *blk,
601 int64_t current_size,
604 int64_t bytes_to_clear;
609 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
610 if (bytes_to_clear) {
611 ret = blk_co_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
613 error_setg_errno(errp, -ret,
614 "Failed to clear the new image's first sector");
623 * Simple implementation of bdrv_co_create_opts for protocol drivers
624 * which only support creation via opening a file
625 * (usually existing raw storage device)
627 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
628 const char *filename,
636 PreallocMode prealloc;
637 Error *local_err = NULL;
642 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
643 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
644 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
645 PREALLOC_MODE_OFF, &local_err);
648 error_propagate(errp, local_err);
652 if (prealloc != PREALLOC_MODE_OFF) {
653 error_setg(errp, "Unsupported preallocation mode '%s'",
654 PreallocMode_str(prealloc));
658 options = qdict_new();
659 qdict_put_str(options, "driver", drv->format_name);
661 blk = blk_co_new_open(filename, NULL, options,
662 BDRV_O_RDWR | BDRV_O_RESIZE, errp);
664 error_prepend(errp, "Protocol driver '%s' does not support image "
665 "creation, and opening the image failed: ",
670 size = create_file_fallback_truncate(blk, size, errp);
676 ret = create_file_fallback_zero_first_sector(blk, size, errp);
687 int coroutine_fn bdrv_co_create_file(const char *filename, QemuOpts *opts,
690 QemuOpts *protocol_opts;
697 drv = bdrv_find_protocol(filename, true, errp);
702 if (!drv->create_opts) {
703 error_setg(errp, "Driver '%s' does not support image creation",
709 * 'opts' contains a QemuOptsList with a combination of format and protocol
712 * The format properly removes its options, but the default values remain
713 * in 'opts->list'. So if the protocol has options with the same name
714 * (e.g. rbd has 'cluster_size' as qcow2), it will see the default values
715 * of the format, since for overlapping options, the format wins.
717 * To avoid this issue, lets convert QemuOpts to QDict, in this way we take
718 * only the set options, and then convert it back to QemuOpts, using the
719 * create_opts of the protocol. So the new QemuOpts, will contain only the
722 qdict = qemu_opts_to_qdict(opts, NULL);
723 protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp);
724 if (protocol_opts == NULL) {
729 ret = bdrv_co_create(drv, filename, protocol_opts, errp);
731 qemu_opts_del(protocol_opts);
732 qobject_unref(qdict);
736 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
738 Error *local_err = NULL;
743 assert_bdrv_graph_readable();
746 error_setg(errp, "Block node '%s' is not opened", bs->filename);
750 if (!bs->drv->bdrv_co_delete_file) {
751 error_setg(errp, "Driver '%s' does not support image deletion",
752 bs->drv->format_name);
756 ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
758 error_propagate(errp, local_err);
764 void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs)
766 Error *local_err = NULL;
774 ret = bdrv_co_delete_file(bs, &local_err);
776 * ENOTSUP will happen if the block driver doesn't support
777 * the 'bdrv_co_delete_file' interface. This is a predictable
778 * scenario and shouldn't be reported back to the user.
780 if (ret == -ENOTSUP) {
781 error_free(local_err);
782 } else if (ret < 0) {
783 error_report_err(local_err);
788 * Try to get @bs's logical and physical block size.
789 * On success, store them in @bsz struct and return 0.
790 * On failure return -errno.
791 * @bs must not be empty.
793 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
795 BlockDriver *drv = bs->drv;
796 BlockDriverState *filtered = bdrv_filter_bs(bs);
799 if (drv && drv->bdrv_probe_blocksizes) {
800 return drv->bdrv_probe_blocksizes(bs, bsz);
801 } else if (filtered) {
802 return bdrv_probe_blocksizes(filtered, bsz);
809 * Try to get @bs's geometry (cyls, heads, sectors).
810 * On success, store them in @geo struct and return 0.
811 * On failure return -errno.
812 * @bs must not be empty.
814 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
816 BlockDriver *drv = bs->drv;
817 BlockDriverState *filtered = bdrv_filter_bs(bs);
820 if (drv && drv->bdrv_probe_geometry) {
821 return drv->bdrv_probe_geometry(bs, geo);
822 } else if (filtered) {
823 return bdrv_probe_geometry(filtered, geo);
830 * Create a uniquely-named empty temporary file.
831 * Return the actual file name used upon success, otherwise NULL.
832 * This string should be freed with g_free() when not needed any longer.
834 * Note: creating a temporary file for the caller to (re)open is
835 * inherently racy. Use g_file_open_tmp() instead whenever practical.
837 char *create_tmp_file(Error **errp)
841 g_autofree char *filename = NULL;
843 tmpdir = g_get_tmp_dir();
846 * See commit 69bef79 ("block: use /var/tmp instead of /tmp for -snapshot")
848 * This function is used to create temporary disk images (like -snapshot),
849 * so the files can become very large. /tmp is often a tmpfs where as
850 * /var/tmp is usually on a disk, so more appropriate for disk images.
852 if (!g_strcmp0(tmpdir, "/tmp")) {
857 filename = g_strdup_printf("%s/vl.XXXXXX", tmpdir);
858 fd = g_mkstemp(filename);
860 error_setg_errno(errp, errno, "Could not open temporary file '%s'",
866 return g_steal_pointer(&filename);
870 * Detect host devices. By convention, /dev/cdrom[N] is always
871 * recognized as a host CDROM.
873 static BlockDriver *find_hdev_driver(const char *filename)
875 int score_max = 0, score;
876 BlockDriver *drv = NULL, *d;
879 QLIST_FOREACH(d, &bdrv_drivers, list) {
880 if (d->bdrv_probe_device) {
881 score = d->bdrv_probe_device(filename);
882 if (score > score_max) {
892 static BlockDriver *bdrv_do_find_protocol(const char *protocol)
897 QLIST_FOREACH(drv1, &bdrv_drivers, list) {
898 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
906 BlockDriver *bdrv_find_protocol(const char *filename,
907 bool allow_protocol_prefix,
917 /* TODO Drivers without bdrv_file_open must be specified explicitly */
920 * XXX(hch): we really should not let host device detection
921 * override an explicit protocol specification, but moving this
922 * later breaks access to device names with colons in them.
923 * Thanks to the brain-dead persistent naming schemes on udev-
924 * based Linux systems those actually are quite common.
926 drv1 = find_hdev_driver(filename);
931 if (!path_has_protocol(filename) || !allow_protocol_prefix) {
935 p = strchr(filename, ':');
938 if (len > sizeof(protocol) - 1)
939 len = sizeof(protocol) - 1;
940 memcpy(protocol, filename, len);
941 protocol[len] = '\0';
943 drv1 = bdrv_do_find_protocol(protocol);
948 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
949 if (block_driver_modules[i].protocol_name &&
950 !strcmp(block_driver_modules[i].protocol_name, protocol)) {
951 int rv = block_module_load(block_driver_modules[i].library_name, errp);
953 drv1 = bdrv_do_find_protocol(protocol);
962 error_setg(errp, "Unknown protocol '%s'", protocol);
968 * Guess image format by probing its contents.
969 * This is not a good idea when your image is raw (CVE-2008-2004), but
970 * we do it anyway for backward compatibility.
972 * @buf contains the image's first @buf_size bytes.
973 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
974 * but can be smaller if the image file is smaller)
975 * @filename is its filename.
977 * For all block drivers, call the bdrv_probe() method to get its
979 * Return the first block driver with the highest probing score.
981 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
982 const char *filename)
984 int score_max = 0, score;
985 BlockDriver *drv = NULL, *d;
988 QLIST_FOREACH(d, &bdrv_drivers, list) {
990 score = d->bdrv_probe(buf, buf_size, filename);
991 if (score > score_max) {
1001 static int find_image_format(BlockBackend *file, const char *filename,
1002 BlockDriver **pdrv, Error **errp)
1005 uint8_t buf[BLOCK_PROBE_BUF_SIZE];
1008 GLOBAL_STATE_CODE();
1010 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */
1011 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
1016 ret = blk_pread(file, 0, sizeof(buf), buf, 0);
1018 error_setg_errno(errp, -ret, "Could not read image for determining its "
1024 drv = bdrv_probe_all(buf, sizeof(buf), filename);
1026 error_setg(errp, "Could not determine image format: No compatible "
1037 * Set the current 'total_sectors' value
1038 * Return 0 on success, -errno on error.
1040 int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs,
1043 BlockDriver *drv = bs->drv;
1045 assert_bdrv_graph_readable();
1051 /* Do not attempt drv->bdrv_co_getlength() on scsi-generic devices */
1055 /* query actual device if possible, otherwise just trust the hint */
1056 if (drv->bdrv_co_getlength) {
1057 int64_t length = drv->bdrv_co_getlength(bs);
1061 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
1064 bs->total_sectors = hint;
1066 if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) {
1074 * Combines a QDict of new block driver @options with any missing options taken
1075 * from @old_options, so that leaving out an option defaults to its old value.
1077 static void bdrv_join_options(BlockDriverState *bs, QDict *options,
1080 GLOBAL_STATE_CODE();
1081 if (bs->drv && bs->drv->bdrv_join_options) {
1082 bs->drv->bdrv_join_options(options, old_options);
1084 qdict_join(options, old_options, false);
1088 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
1092 Error *local_err = NULL;
1093 char *value = qemu_opt_get_del(opts, "detect-zeroes");
1094 BlockdevDetectZeroesOptions detect_zeroes =
1095 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
1096 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
1097 GLOBAL_STATE_CODE();
1100 error_propagate(errp, local_err);
1101 return detect_zeroes;
1104 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
1105 !(open_flags & BDRV_O_UNMAP))
1107 error_setg(errp, "setting detect-zeroes to unmap is not allowed "
1108 "without setting discard operation to unmap");
1111 return detect_zeroes;
1115 * Set open flags for aio engine
1117 * Return 0 on success, -1 if the engine specified is invalid
1119 int bdrv_parse_aio(const char *mode, int *flags)
1121 if (!strcmp(mode, "threads")) {
1122 /* do nothing, default */
1123 } else if (!strcmp(mode, "native")) {
1124 *flags |= BDRV_O_NATIVE_AIO;
1125 #ifdef CONFIG_LINUX_IO_URING
1126 } else if (!strcmp(mode, "io_uring")) {
1127 *flags |= BDRV_O_IO_URING;
1137 * Set open flags for a given discard mode
1139 * Return 0 on success, -1 if the discard mode was invalid.
1141 int bdrv_parse_discard_flags(const char *mode, int *flags)
1143 *flags &= ~BDRV_O_UNMAP;
1145 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
1147 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
1148 *flags |= BDRV_O_UNMAP;
1157 * Set open flags for a given cache mode
1159 * Return 0 on success, -1 if the cache mode was invalid.
1161 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
1163 *flags &= ~BDRV_O_CACHE_MASK;
1165 if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
1166 *writethrough = false;
1167 *flags |= BDRV_O_NOCACHE;
1168 } else if (!strcmp(mode, "directsync")) {
1169 *writethrough = true;
1170 *flags |= BDRV_O_NOCACHE;
1171 } else if (!strcmp(mode, "writeback")) {
1172 *writethrough = false;
1173 } else if (!strcmp(mode, "unsafe")) {
1174 *writethrough = false;
1175 *flags |= BDRV_O_NO_FLUSH;
1176 } else if (!strcmp(mode, "writethrough")) {
1177 *writethrough = true;
1185 static char *bdrv_child_get_parent_desc(BdrvChild *c)
1187 BlockDriverState *parent = c->opaque;
1188 return g_strdup_printf("node '%s'", bdrv_get_node_name(parent));
1191 static void bdrv_child_cb_drained_begin(BdrvChild *child)
1193 BlockDriverState *bs = child->opaque;
1194 bdrv_do_drained_begin_quiesce(bs, NULL);
1197 static bool bdrv_child_cb_drained_poll(BdrvChild *child)
1199 BlockDriverState *bs = child->opaque;
1200 return bdrv_drain_poll(bs, NULL, false);
1203 static void bdrv_child_cb_drained_end(BdrvChild *child)
1205 BlockDriverState *bs = child->opaque;
1206 bdrv_drained_end(bs);
1209 static int bdrv_child_cb_inactivate(BdrvChild *child)
1211 BlockDriverState *bs = child->opaque;
1212 GLOBAL_STATE_CODE();
1213 assert(bs->open_flags & BDRV_O_INACTIVE);
1217 static bool bdrv_child_cb_change_aio_ctx(BdrvChild *child, AioContext *ctx,
1218 GHashTable *visited, Transaction *tran,
1221 BlockDriverState *bs = child->opaque;
1222 return bdrv_change_aio_context(bs, ctx, visited, tran, errp);
1226 * Returns the options and flags that a temporary snapshot should get, based on
1227 * the originally requested flags (the originally requested image will have
1228 * flags like a backing file)
1230 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
1231 int parent_flags, QDict *parent_options)
1233 GLOBAL_STATE_CODE();
1234 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
1236 /* For temporary files, unconditional cache=unsafe is fine */
1237 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
1238 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
1240 /* Copy the read-only and discard options from the parent */
1241 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1242 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
1244 /* aio=native doesn't work for cache.direct=off, so disable it for the
1245 * temporary snapshot */
1246 *child_flags &= ~BDRV_O_NATIVE_AIO;
1249 static void bdrv_backing_attach(BdrvChild *c)
1251 BlockDriverState *parent = c->opaque;
1252 BlockDriverState *backing_hd = c->bs;
1254 GLOBAL_STATE_CODE();
1255 assert(!parent->backing_blocker);
1256 error_setg(&parent->backing_blocker,
1257 "node is used as backing hd of '%s'",
1258 bdrv_get_device_or_node_name(parent));
1260 bdrv_refresh_filename(backing_hd);
1262 parent->open_flags &= ~BDRV_O_NO_BACKING;
1264 bdrv_op_block_all(backing_hd, parent->backing_blocker);
1265 /* Otherwise we won't be able to commit or stream */
1266 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
1267 parent->backing_blocker);
1268 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
1269 parent->backing_blocker);
1271 * We do backup in 3 ways:
1273 * The target bs is new opened, and the source is top BDS
1274 * 2. blockdev backup
1275 * Both the source and the target are top BDSes.
1276 * 3. internal backup(used for block replication)
1277 * Both the source and the target are backing file
1279 * In case 1 and 2, neither the source nor the target is the backing file.
1280 * In case 3, we will block the top BDS, so there is only one block job
1281 * for the top BDS and its backing chain.
1283 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
1284 parent->backing_blocker);
1285 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
1286 parent->backing_blocker);
1289 static void bdrv_backing_detach(BdrvChild *c)
1291 BlockDriverState *parent = c->opaque;
1293 GLOBAL_STATE_CODE();
1294 assert(parent->backing_blocker);
1295 bdrv_op_unblock_all(c->bs, parent->backing_blocker);
1296 error_free(parent->backing_blocker);
1297 parent->backing_blocker = NULL;
1300 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
1301 const char *filename, Error **errp)
1303 BlockDriverState *parent = c->opaque;
1304 bool read_only = bdrv_is_read_only(parent);
1306 GLOBAL_STATE_CODE();
1309 ret = bdrv_reopen_set_read_only(parent, false, errp);
1315 ret = bdrv_change_backing_file(parent, filename,
1316 base->drv ? base->drv->format_name : "",
1319 error_setg_errno(errp, -ret, "Could not update backing file link");
1323 bdrv_reopen_set_read_only(parent, true, NULL);
1330 * Returns the options and flags that a generic child of a BDS should
1331 * get, based on the given options and flags for the parent BDS.
1333 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
1334 int *child_flags, QDict *child_options,
1335 int parent_flags, QDict *parent_options)
1337 int flags = parent_flags;
1338 GLOBAL_STATE_CODE();
1341 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL.
1342 * Generally, the question to answer is: Should this child be
1343 * format-probed by default?
1347 * Pure and non-filtered data children of non-format nodes should
1348 * be probed by default (even when the node itself has BDRV_O_PROTOCOL
1349 * set). This only affects a very limited set of drivers (namely
1350 * quorum and blkverify when this comment was written).
1351 * Force-clear BDRV_O_PROTOCOL then.
1353 if (!parent_is_format &&
1354 (role & BDRV_CHILD_DATA) &&
1355 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED)))
1357 flags &= ~BDRV_O_PROTOCOL;
1361 * All children of format nodes (except for COW children) and all
1362 * metadata children in general should never be format-probed.
1363 * Force-set BDRV_O_PROTOCOL then.
1365 if ((parent_is_format && !(role & BDRV_CHILD_COW)) ||
1366 (role & BDRV_CHILD_METADATA))
1368 flags |= BDRV_O_PROTOCOL;
1372 * If the cache mode isn't explicitly set, inherit direct and no-flush from
1375 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
1376 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
1377 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
1379 if (role & BDRV_CHILD_COW) {
1380 /* backing files are opened read-only by default */
1381 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
1382 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
1384 /* Inherit the read-only option from the parent if it's not set */
1385 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
1386 qdict_copy_default(child_options, parent_options,
1387 BDRV_OPT_AUTO_READ_ONLY);
1391 * bdrv_co_pdiscard() respects unmap policy for the parent, so we
1392 * can default to enable it on lower layers regardless of the
1395 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
1397 /* Clear flags that only apply to the top layer */
1398 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
1400 if (role & BDRV_CHILD_METADATA) {
1401 flags &= ~BDRV_O_NO_IO;
1403 if (role & BDRV_CHILD_COW) {
1404 flags &= ~BDRV_O_TEMPORARY;
1407 *child_flags = flags;
1410 static void GRAPH_WRLOCK bdrv_child_cb_attach(BdrvChild *child)
1412 BlockDriverState *bs = child->opaque;
1414 assert_bdrv_graph_writable();
1415 QLIST_INSERT_HEAD(&bs->children, child, next);
1416 if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) {
1418 * Here we handle filters and block/raw-format.c when it behave like
1419 * filter. They generally have a single PRIMARY child, which is also the
1420 * FILTERED child, and that they may have multiple more children, which
1421 * are neither PRIMARY nor FILTERED. And never we have a COW child here.
1422 * So bs->file will be the PRIMARY child, unless the PRIMARY child goes
1423 * into bs->backing on exceptional cases; and bs->backing will be
1426 assert(!(child->role & BDRV_CHILD_COW));
1427 if (child->role & BDRV_CHILD_PRIMARY) {
1428 assert(child->role & BDRV_CHILD_FILTERED);
1429 assert(!bs->backing);
1432 if (bs->drv->filtered_child_is_backing) {
1433 bs->backing = child;
1438 assert(!(child->role & BDRV_CHILD_FILTERED));
1440 } else if (child->role & BDRV_CHILD_COW) {
1441 assert(bs->drv->supports_backing);
1442 assert(!(child->role & BDRV_CHILD_PRIMARY));
1443 assert(!bs->backing);
1444 bs->backing = child;
1445 bdrv_backing_attach(child);
1446 } else if (child->role & BDRV_CHILD_PRIMARY) {
1452 static void GRAPH_WRLOCK bdrv_child_cb_detach(BdrvChild *child)
1454 BlockDriverState *bs = child->opaque;
1456 if (child->role & BDRV_CHILD_COW) {
1457 bdrv_backing_detach(child);
1460 assert_bdrv_graph_writable();
1461 QLIST_REMOVE(child, next);
1462 if (child == bs->backing) {
1463 assert(child != bs->file);
1465 } else if (child == bs->file) {
1470 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
1471 const char *filename, Error **errp)
1473 if (c->role & BDRV_CHILD_COW) {
1474 return bdrv_backing_update_filename(c, base, filename, errp);
1479 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c)
1481 BlockDriverState *bs = c->opaque;
1484 return bdrv_get_aio_context(bs);
1487 const BdrvChildClass child_of_bds = {
1488 .parent_is_bds = true,
1489 .get_parent_desc = bdrv_child_get_parent_desc,
1490 .inherit_options = bdrv_inherited_options,
1491 .drained_begin = bdrv_child_cb_drained_begin,
1492 .drained_poll = bdrv_child_cb_drained_poll,
1493 .drained_end = bdrv_child_cb_drained_end,
1494 .attach = bdrv_child_cb_attach,
1495 .detach = bdrv_child_cb_detach,
1496 .inactivate = bdrv_child_cb_inactivate,
1497 .change_aio_ctx = bdrv_child_cb_change_aio_ctx,
1498 .update_filename = bdrv_child_cb_update_filename,
1499 .get_parent_aio_context = child_of_bds_get_parent_aio_context,
1502 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c)
1505 return c->klass->get_parent_aio_context(c);
1508 static int bdrv_open_flags(BlockDriverState *bs, int flags)
1510 int open_flags = flags;
1511 GLOBAL_STATE_CODE();
1514 * Clear flags that are internal to the block layer before opening the
1517 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
1522 static void update_flags_from_options(int *flags, QemuOpts *opts)
1524 GLOBAL_STATE_CODE();
1526 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
1528 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
1529 *flags |= BDRV_O_NO_FLUSH;
1532 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
1533 *flags |= BDRV_O_NOCACHE;
1536 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
1537 *flags |= BDRV_O_RDWR;
1540 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
1541 *flags |= BDRV_O_AUTO_RDONLY;
1545 static void update_options_from_flags(QDict *options, int flags)
1547 GLOBAL_STATE_CODE();
1548 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
1549 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
1551 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
1552 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
1553 flags & BDRV_O_NO_FLUSH);
1555 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
1556 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
1558 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
1559 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
1560 flags & BDRV_O_AUTO_RDONLY);
1564 static void bdrv_assign_node_name(BlockDriverState *bs,
1565 const char *node_name,
1568 char *gen_node_name = NULL;
1569 GLOBAL_STATE_CODE();
1572 node_name = gen_node_name = id_generate(ID_BLOCK);
1573 } else if (!id_wellformed(node_name)) {
1575 * Check for empty string or invalid characters, but not if it is
1576 * generated (generated names use characters not available to the user)
1578 error_setg(errp, "Invalid node-name: '%s'", node_name);
1582 /* takes care of avoiding namespaces collisions */
1583 if (blk_by_name(node_name)) {
1584 error_setg(errp, "node-name=%s is conflicting with a device id",
1589 /* takes care of avoiding duplicates node names */
1590 if (bdrv_find_node(node_name)) {
1591 error_setg(errp, "Duplicate nodes with node-name='%s'", node_name);
1595 /* Make sure that the node name isn't truncated */
1596 if (strlen(node_name) >= sizeof(bs->node_name)) {
1597 error_setg(errp, "Node name too long");
1601 /* copy node name into the bs and insert it into the graph list */
1602 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
1603 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
1605 g_free(gen_node_name);
1609 * The caller must always hold @bs AioContext lock, because this function calls
1610 * bdrv_refresh_total_sectors() which polls when called from non-coroutine
1613 static int no_coroutine_fn GRAPH_UNLOCKED
1614 bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name,
1615 QDict *options, int open_flags, Error **errp)
1618 Error *local_err = NULL;
1620 GLOBAL_STATE_CODE();
1622 bdrv_assign_node_name(bs, node_name, &local_err);
1624 error_propagate(errp, local_err);
1629 bs->opaque = g_malloc0(drv->instance_size);
1631 if (drv->bdrv_file_open) {
1632 assert(!drv->bdrv_needs_filename || bs->filename[0]);
1633 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
1634 } else if (drv->bdrv_open) {
1635 ret = drv->bdrv_open(bs, options, open_flags, &local_err);
1642 error_propagate(errp, local_err);
1643 } else if (bs->filename[0]) {
1644 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
1646 error_setg_errno(errp, -ret, "Could not open image");
1651 assert(!(bs->supported_read_flags & ~BDRV_REQ_MASK));
1652 assert(!(bs->supported_write_flags & ~BDRV_REQ_MASK));
1655 * Always allow the BDRV_REQ_REGISTERED_BUF optimization hint. This saves
1656 * drivers that pass read/write requests through to a child the trouble of
1657 * declaring support explicitly.
1659 * Drivers must not propagate this flag accidentally when they initiate I/O
1660 * to a bounce buffer. That case should be rare though.
1662 bs->supported_read_flags |= BDRV_REQ_REGISTERED_BUF;
1663 bs->supported_write_flags |= BDRV_REQ_REGISTERED_BUF;
1665 /* Get the context after .bdrv_open, it can change the context */
1666 ctx = bdrv_get_aio_context(bs);
1667 aio_context_acquire(ctx);
1669 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
1671 error_setg_errno(errp, -ret, "Could not refresh total sector count");
1672 aio_context_release(ctx);
1676 bdrv_graph_rdlock_main_loop();
1677 bdrv_refresh_limits(bs, NULL, &local_err);
1678 bdrv_graph_rdunlock_main_loop();
1679 aio_context_release(ctx);
1682 error_propagate(errp, local_err);
1686 assert(bdrv_opt_mem_align(bs) != 0);
1687 assert(bdrv_min_mem_align(bs) != 0);
1688 assert(is_power_of_2(bs->bl.request_alignment));
1690 for (i = 0; i < bs->quiesce_counter; i++) {
1691 if (drv->bdrv_drain_begin) {
1692 drv->bdrv_drain_begin(bs);
1699 if (bs->file != NULL) {
1700 bdrv_unref_child(bs, bs->file);
1709 * Create and open a block node.
1711 * @options is a QDict of options to pass to the block drivers, or NULL for an
1712 * empty set of options. The reference to the QDict belongs to the block layer
1713 * after the call (even on failure), so if the caller intends to reuse the
1714 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
1716 BlockDriverState *bdrv_new_open_driver_opts(BlockDriver *drv,
1717 const char *node_name,
1718 QDict *options, int flags,
1721 BlockDriverState *bs;
1724 GLOBAL_STATE_CODE();
1727 bs->open_flags = flags;
1728 bs->options = options ?: qdict_new();
1729 bs->explicit_options = qdict_clone_shallow(bs->options);
1732 update_options_from_flags(bs->options, flags);
1734 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
1736 qobject_unref(bs->explicit_options);
1737 bs->explicit_options = NULL;
1738 qobject_unref(bs->options);
1747 /* Create and open a block node. */
1748 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
1749 int flags, Error **errp)
1751 GLOBAL_STATE_CODE();
1752 return bdrv_new_open_driver_opts(drv, node_name, NULL, flags, errp);
1755 QemuOptsList bdrv_runtime_opts = {
1756 .name = "bdrv_common",
1757 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
1760 .name = "node-name",
1761 .type = QEMU_OPT_STRING,
1762 .help = "Node name of the block device node",
1766 .type = QEMU_OPT_STRING,
1767 .help = "Block driver to use for the node",
1770 .name = BDRV_OPT_CACHE_DIRECT,
1771 .type = QEMU_OPT_BOOL,
1772 .help = "Bypass software writeback cache on the host",
1775 .name = BDRV_OPT_CACHE_NO_FLUSH,
1776 .type = QEMU_OPT_BOOL,
1777 .help = "Ignore flush requests",
1780 .name = BDRV_OPT_READ_ONLY,
1781 .type = QEMU_OPT_BOOL,
1782 .help = "Node is opened in read-only mode",
1785 .name = BDRV_OPT_AUTO_READ_ONLY,
1786 .type = QEMU_OPT_BOOL,
1787 .help = "Node can become read-only if opening read-write fails",
1790 .name = "detect-zeroes",
1791 .type = QEMU_OPT_STRING,
1792 .help = "try to optimize zero writes (off, on, unmap)",
1795 .name = BDRV_OPT_DISCARD,
1796 .type = QEMU_OPT_STRING,
1797 .help = "discard operation (ignore/off, unmap/on)",
1800 .name = BDRV_OPT_FORCE_SHARE,
1801 .type = QEMU_OPT_BOOL,
1802 .help = "always accept other writers (default: off)",
1804 { /* end of list */ }
1808 QemuOptsList bdrv_create_opts_simple = {
1809 .name = "simple-create-opts",
1810 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head),
1813 .name = BLOCK_OPT_SIZE,
1814 .type = QEMU_OPT_SIZE,
1815 .help = "Virtual disk size"
1818 .name = BLOCK_OPT_PREALLOC,
1819 .type = QEMU_OPT_STRING,
1820 .help = "Preallocation mode (allowed values: off)"
1822 { /* end of list */ }
1827 * Common part for opening disk images and files
1829 * Removes all processed options from *options.
1831 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
1832 QDict *options, Error **errp)
1834 int ret, open_flags;
1835 const char *filename;
1836 const char *driver_name = NULL;
1837 const char *node_name = NULL;
1838 const char *discard;
1841 Error *local_err = NULL;
1844 assert(bs->file == NULL);
1845 assert(options != NULL && bs->options != options);
1846 GLOBAL_STATE_CODE();
1848 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
1849 if (!qemu_opts_absorb_qdict(opts, options, errp)) {
1854 update_flags_from_options(&bs->open_flags, opts);
1856 driver_name = qemu_opt_get(opts, "driver");
1857 drv = bdrv_find_format(driver_name);
1858 assert(drv != NULL);
1860 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
1862 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
1864 BDRV_OPT_FORCE_SHARE
1865 "=on can only be used with read-only images");
1871 bdrv_refresh_filename(blk_bs(file));
1872 filename = blk_bs(file)->filename;
1875 * Caution: while qdict_get_try_str() is fine, getting
1876 * non-string types would require more care. When @options
1877 * come from -blockdev or blockdev_add, its members are typed
1878 * according to the QAPI schema, but when they come from
1879 * -drive, they're all QString.
1881 filename = qdict_get_try_str(options, "filename");
1884 if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
1885 error_setg(errp, "The '%s' block driver requires a file name",
1891 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
1894 ro = bdrv_is_read_only(bs);
1896 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, ro)) {
1897 if (!ro && bdrv_is_whitelisted(drv, true)) {
1898 ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
1904 !ro && bdrv_is_whitelisted(drv, true)
1905 ? "Driver '%s' can only be used for read-only devices"
1906 : "Driver '%s' is not whitelisted",
1912 /* bdrv_new() and bdrv_close() make it so */
1913 assert(qatomic_read(&bs->copy_on_read) == 0);
1915 if (bs->open_flags & BDRV_O_COPY_ON_READ) {
1917 bdrv_enable_copy_on_read(bs);
1919 error_setg(errp, "Can't use copy-on-read on read-only device");
1925 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
1926 if (discard != NULL) {
1927 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
1928 error_setg(errp, "Invalid discard option");
1935 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
1937 error_propagate(errp, local_err);
1942 if (filename != NULL) {
1943 pstrcpy(bs->filename, sizeof(bs->filename), filename);
1945 bs->filename[0] = '\0';
1947 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
1949 /* Open the image, either directly or using a protocol */
1950 open_flags = bdrv_open_flags(bs, bs->open_flags);
1951 node_name = qemu_opt_get(opts, "node-name");
1953 assert(!drv->bdrv_file_open || file == NULL);
1954 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
1959 qemu_opts_del(opts);
1963 qemu_opts_del(opts);
1967 static QDict *parse_json_filename(const char *filename, Error **errp)
1969 QObject *options_obj;
1972 GLOBAL_STATE_CODE();
1974 ret = strstart(filename, "json:", &filename);
1977 options_obj = qobject_from_json(filename, errp);
1979 error_prepend(errp, "Could not parse the JSON options: ");
1983 options = qobject_to(QDict, options_obj);
1985 qobject_unref(options_obj);
1986 error_setg(errp, "Invalid JSON object given");
1990 qdict_flatten(options);
1995 static void parse_json_protocol(QDict *options, const char **pfilename,
1998 QDict *json_options;
1999 Error *local_err = NULL;
2000 GLOBAL_STATE_CODE();
2002 /* Parse json: pseudo-protocol */
2003 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
2007 json_options = parse_json_filename(*pfilename, &local_err);
2009 error_propagate(errp, local_err);
2013 /* Options given in the filename have lower priority than options
2014 * specified directly */
2015 qdict_join(options, json_options, false);
2016 qobject_unref(json_options);
2021 * Fills in default options for opening images and converts the legacy
2022 * filename/flags pair to option QDict entries.
2023 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
2024 * block driver has been specified explicitly.
2026 static int bdrv_fill_options(QDict **options, const char *filename,
2027 int *flags, Error **errp)
2029 const char *drvname;
2030 bool protocol = *flags & BDRV_O_PROTOCOL;
2031 bool parse_filename = false;
2032 BlockDriver *drv = NULL;
2033 Error *local_err = NULL;
2035 GLOBAL_STATE_CODE();
2038 * Caution: while qdict_get_try_str() is fine, getting non-string
2039 * types would require more care. When @options come from
2040 * -blockdev or blockdev_add, its members are typed according to
2041 * the QAPI schema, but when they come from -drive, they're all
2044 drvname = qdict_get_try_str(*options, "driver");
2046 drv = bdrv_find_format(drvname);
2048 error_setg(errp, "Unknown driver '%s'", drvname);
2051 /* If the user has explicitly specified the driver, this choice should
2052 * override the BDRV_O_PROTOCOL flag */
2053 protocol = drv->bdrv_file_open;
2057 *flags |= BDRV_O_PROTOCOL;
2059 *flags &= ~BDRV_O_PROTOCOL;
2062 /* Translate cache options from flags into options */
2063 update_options_from_flags(*options, *flags);
2065 /* Fetch the file name from the options QDict if necessary */
2066 if (protocol && filename) {
2067 if (!qdict_haskey(*options, "filename")) {
2068 qdict_put_str(*options, "filename", filename);
2069 parse_filename = true;
2071 error_setg(errp, "Can't specify 'file' and 'filename' options at "
2077 /* Find the right block driver */
2078 /* See cautionary note on accessing @options above */
2079 filename = qdict_get_try_str(*options, "filename");
2081 if (!drvname && protocol) {
2083 drv = bdrv_find_protocol(filename, parse_filename, errp);
2088 drvname = drv->format_name;
2089 qdict_put_str(*options, "driver", drvname);
2091 error_setg(errp, "Must specify either driver or file");
2096 assert(drv || !protocol);
2098 /* Driver-specific filename parsing */
2099 if (drv && drv->bdrv_parse_filename && parse_filename) {
2100 drv->bdrv_parse_filename(filename, *options, &local_err);
2102 error_propagate(errp, local_err);
2106 if (!drv->bdrv_needs_filename) {
2107 qdict_del(*options, "filename");
2114 typedef struct BlockReopenQueueEntry {
2117 BDRVReopenState state;
2118 QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
2119 } BlockReopenQueueEntry;
2122 * Return the flags that @bs will have after the reopens in @q have
2123 * successfully completed. If @q is NULL (or @bs is not contained in @q),
2124 * return the current flags.
2126 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
2128 BlockReopenQueueEntry *entry;
2131 QTAILQ_FOREACH(entry, q, entry) {
2132 if (entry->state.bs == bs) {
2133 return entry->state.flags;
2138 return bs->open_flags;
2141 /* Returns whether the image file can be written to after the reopen queue @q
2142 * has been successfully applied, or right now if @q is NULL. */
2143 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
2144 BlockReopenQueue *q)
2146 int flags = bdrv_reopen_get_flags(q, bs);
2148 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
2152 * Return whether the BDS can be written to. This is not necessarily
2153 * the same as !bdrv_is_read_only(bs), as inactivated images may not
2154 * be written to but do not count as read-only images.
2156 bool bdrv_is_writable(BlockDriverState *bs)
2159 return bdrv_is_writable_after_reopen(bs, NULL);
2162 static char *bdrv_child_user_desc(BdrvChild *c)
2164 GLOBAL_STATE_CODE();
2165 return c->klass->get_parent_desc(c);
2169 * Check that @a allows everything that @b needs. @a and @b must reference same
2172 static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
2174 const char *child_bs_name;
2175 g_autofree char *a_user = NULL;
2176 g_autofree char *b_user = NULL;
2177 g_autofree char *perms = NULL;
2180 assert(a->bs == b->bs);
2181 GLOBAL_STATE_CODE();
2183 if ((b->perm & a->shared_perm) == b->perm) {
2187 child_bs_name = bdrv_get_node_name(b->bs);
2188 a_user = bdrv_child_user_desc(a);
2189 b_user = bdrv_child_user_desc(b);
2190 perms = bdrv_perm_names(b->perm & ~a->shared_perm);
2192 error_setg(errp, "Permission conflict on node '%s': permissions '%s' are "
2193 "both required by %s (uses node '%s' as '%s' child) and "
2194 "unshared by %s (uses node '%s' as '%s' child).",
2195 child_bs_name, perms,
2196 b_user, child_bs_name, b->name,
2197 a_user, child_bs_name, a->name);
2202 static bool bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
2205 GLOBAL_STATE_CODE();
2208 * During the loop we'll look at each pair twice. That's correct because
2209 * bdrv_a_allow_b() is asymmetric and we should check each pair in both
2212 QLIST_FOREACH(a, &bs->parents, next_parent) {
2213 QLIST_FOREACH(b, &bs->parents, next_parent) {
2218 if (!bdrv_a_allow_b(a, b, errp)) {
2227 static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
2228 BdrvChild *c, BdrvChildRole role,
2229 BlockReopenQueue *reopen_queue,
2230 uint64_t parent_perm, uint64_t parent_shared,
2231 uint64_t *nperm, uint64_t *nshared)
2233 assert(bs->drv && bs->drv->bdrv_child_perm);
2234 GLOBAL_STATE_CODE();
2235 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
2236 parent_perm, parent_shared,
2238 /* TODO Take force_share from reopen_queue */
2239 if (child_bs && child_bs->force_share) {
2240 *nshared = BLK_PERM_ALL;
2245 * Adds the whole subtree of @bs (including @bs itself) to the @list (except for
2246 * nodes that are already in the @list, of course) so that final list is
2247 * topologically sorted. Return the result (GSList @list object is updated, so
2248 * don't use old reference after function call).
2250 * On function start @list must be already topologically sorted and for any node
2251 * in the @list the whole subtree of the node must be in the @list as well. The
2252 * simplest way to satisfy this criteria: use only result of
2253 * bdrv_topological_dfs() or NULL as @list parameter.
2255 static GSList *bdrv_topological_dfs(GSList *list, GHashTable *found,
2256 BlockDriverState *bs)
2259 g_autoptr(GHashTable) local_found = NULL;
2261 GLOBAL_STATE_CODE();
2265 found = local_found = g_hash_table_new(NULL, NULL);
2268 if (g_hash_table_contains(found, bs)) {
2271 g_hash_table_add(found, bs);
2273 QLIST_FOREACH(child, &bs->children, next) {
2274 list = bdrv_topological_dfs(list, found, child->bs);
2277 return g_slist_prepend(list, bs);
2280 typedef struct BdrvChildSetPermState {
2283 uint64_t old_shared_perm;
2284 } BdrvChildSetPermState;
2286 static void bdrv_child_set_perm_abort(void *opaque)
2288 BdrvChildSetPermState *s = opaque;
2290 GLOBAL_STATE_CODE();
2292 s->child->perm = s->old_perm;
2293 s->child->shared_perm = s->old_shared_perm;
2296 static TransactionActionDrv bdrv_child_set_pem_drv = {
2297 .abort = bdrv_child_set_perm_abort,
2301 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm,
2302 uint64_t shared, Transaction *tran)
2304 BdrvChildSetPermState *s = g_new(BdrvChildSetPermState, 1);
2305 GLOBAL_STATE_CODE();
2307 *s = (BdrvChildSetPermState) {
2309 .old_perm = c->perm,
2310 .old_shared_perm = c->shared_perm,
2314 c->shared_perm = shared;
2316 tran_add(tran, &bdrv_child_set_pem_drv, s);
2319 static void bdrv_drv_set_perm_commit(void *opaque)
2321 BlockDriverState *bs = opaque;
2322 uint64_t cumulative_perms, cumulative_shared_perms;
2323 GLOBAL_STATE_CODE();
2325 if (bs->drv->bdrv_set_perm) {
2326 bdrv_get_cumulative_perm(bs, &cumulative_perms,
2327 &cumulative_shared_perms);
2328 bs->drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
2332 static void bdrv_drv_set_perm_abort(void *opaque)
2334 BlockDriverState *bs = opaque;
2335 GLOBAL_STATE_CODE();
2337 if (bs->drv->bdrv_abort_perm_update) {
2338 bs->drv->bdrv_abort_perm_update(bs);
2342 TransactionActionDrv bdrv_drv_set_perm_drv = {
2343 .abort = bdrv_drv_set_perm_abort,
2344 .commit = bdrv_drv_set_perm_commit,
2347 static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm,
2348 uint64_t shared_perm, Transaction *tran,
2351 GLOBAL_STATE_CODE();
2356 if (bs->drv->bdrv_check_perm) {
2357 int ret = bs->drv->bdrv_check_perm(bs, perm, shared_perm, errp);
2364 tran_add(tran, &bdrv_drv_set_perm_drv, bs);
2370 typedef struct BdrvReplaceChildState {
2372 BlockDriverState *old_bs;
2373 } BdrvReplaceChildState;
2375 static void bdrv_replace_child_commit(void *opaque)
2377 BdrvReplaceChildState *s = opaque;
2378 GLOBAL_STATE_CODE();
2380 bdrv_unref(s->old_bs);
2383 static void bdrv_replace_child_abort(void *opaque)
2385 BdrvReplaceChildState *s = opaque;
2386 BlockDriverState *new_bs = s->child->bs;
2388 GLOBAL_STATE_CODE();
2389 /* old_bs reference is transparently moved from @s to @s->child */
2390 if (!s->child->bs) {
2392 * The parents were undrained when removing old_bs from the child. New
2393 * requests can't have been made, though, because the child was empty.
2395 * TODO Make bdrv_replace_child_noperm() transactionable to avoid
2396 * undraining the parent in the first place. Once this is done, having
2397 * new_bs drained when calling bdrv_replace_child_tran() is not a
2398 * requirement any more.
2400 bdrv_parent_drained_begin_single(s->child);
2401 assert(!bdrv_parent_drained_poll_single(s->child));
2403 assert(s->child->quiesced_parent);
2404 bdrv_replace_child_noperm(s->child, s->old_bs);
2408 static TransactionActionDrv bdrv_replace_child_drv = {
2409 .commit = bdrv_replace_child_commit,
2410 .abort = bdrv_replace_child_abort,
2415 * bdrv_replace_child_tran
2417 * Note: real unref of old_bs is done only on commit.
2419 * Both @child->bs and @new_bs (if non-NULL) must be drained. @new_bs must be
2420 * kept drained until the transaction is completed.
2422 * The function doesn't update permissions, caller is responsible for this.
2424 static void bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
2427 BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
2429 assert(child->quiesced_parent);
2430 assert(!new_bs || new_bs->quiesce_counter);
2432 *s = (BdrvReplaceChildState) {
2434 .old_bs = child->bs,
2436 tran_add(tran, &bdrv_replace_child_drv, s);
2441 bdrv_replace_child_noperm(child, new_bs);
2442 /* old_bs reference is transparently moved from @child to @s */
2446 * Refresh permissions in @bs subtree. The function is intended to be called
2447 * after some graph modification that was done without permission update.
2449 static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
2450 Transaction *tran, Error **errp)
2452 BlockDriver *drv = bs->drv;
2455 uint64_t cumulative_perms, cumulative_shared_perms;
2456 GLOBAL_STATE_CODE();
2458 bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms);
2460 /* Write permissions never work with read-only images */
2461 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2462 !bdrv_is_writable_after_reopen(bs, q))
2464 if (!bdrv_is_writable_after_reopen(bs, NULL)) {
2465 error_setg(errp, "Block node is read-only");
2467 error_setg(errp, "Read-only block node '%s' cannot support "
2468 "read-write users", bdrv_get_node_name(bs));
2475 * Unaligned requests will automatically be aligned to bl.request_alignment
2476 * and without RESIZE we can't extend requests to write to space beyond the
2477 * end of the image, so it's required that the image size is aligned.
2479 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
2480 !(cumulative_perms & BLK_PERM_RESIZE))
2482 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) {
2483 error_setg(errp, "Cannot get 'write' permission without 'resize': "
2484 "Image size is not a multiple of request "
2490 /* Check this node */
2495 ret = bdrv_drv_set_perm(bs, cumulative_perms, cumulative_shared_perms, tran,
2501 /* Drivers that never have children can omit .bdrv_child_perm() */
2502 if (!drv->bdrv_child_perm) {
2503 assert(QLIST_EMPTY(&bs->children));
2507 /* Check all children */
2508 QLIST_FOREACH(c, &bs->children, next) {
2509 uint64_t cur_perm, cur_shared;
2511 bdrv_child_perm(bs, c->bs, c, c->role, q,
2512 cumulative_perms, cumulative_shared_perms,
2513 &cur_perm, &cur_shared);
2514 bdrv_child_set_perm(c, cur_perm, cur_shared, tran);
2521 * @list is a product of bdrv_topological_dfs() (may be called several times) -
2522 * a topologically sorted subgraph.
2524 static int bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q,
2525 Transaction *tran, Error **errp)
2528 BlockDriverState *bs;
2529 GLOBAL_STATE_CODE();
2531 for ( ; list; list = list->next) {
2534 if (bdrv_parent_perms_conflict(bs, errp)) {
2538 ret = bdrv_node_refresh_perm(bs, q, tran, errp);
2548 * @list is any list of nodes. List is completed by all subtrees and
2549 * topologically sorted. It's not a problem if some node occurs in the @list
2552 static int bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q,
2553 Transaction *tran, Error **errp)
2555 g_autoptr(GHashTable) found = g_hash_table_new(NULL, NULL);
2556 g_autoptr(GSList) refresh_list = NULL;
2558 for ( ; list; list = list->next) {
2559 refresh_list = bdrv_topological_dfs(refresh_list, found, list->data);
2562 return bdrv_do_refresh_perms(refresh_list, q, tran, errp);
2565 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
2566 uint64_t *shared_perm)
2569 uint64_t cumulative_perms = 0;
2570 uint64_t cumulative_shared_perms = BLK_PERM_ALL;
2572 GLOBAL_STATE_CODE();
2574 QLIST_FOREACH(c, &bs->parents, next_parent) {
2575 cumulative_perms |= c->perm;
2576 cumulative_shared_perms &= c->shared_perm;
2579 *perm = cumulative_perms;
2580 *shared_perm = cumulative_shared_perms;
2583 char *bdrv_perm_names(uint64_t perm)
2589 { BLK_PERM_CONSISTENT_READ, "consistent read" },
2590 { BLK_PERM_WRITE, "write" },
2591 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
2592 { BLK_PERM_RESIZE, "resize" },
2596 GString *result = g_string_sized_new(30);
2597 struct perm_name *p;
2599 for (p = permissions; p->name; p++) {
2600 if (perm & p->perm) {
2601 if (result->len > 0) {
2602 g_string_append(result, ", ");
2604 g_string_append(result, p->name);
2608 return g_string_free(result, FALSE);
2612 /* @tran is allowed to be NULL. In this case no rollback is possible */
2613 static int bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran,
2617 Transaction *local_tran = NULL;
2618 g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs);
2619 GLOBAL_STATE_CODE();
2622 tran = local_tran = tran_new();
2625 ret = bdrv_do_refresh_perms(list, NULL, tran, errp);
2628 tran_finalize(local_tran, ret);
2634 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
2637 Error *local_err = NULL;
2638 Transaction *tran = tran_new();
2641 GLOBAL_STATE_CODE();
2643 bdrv_child_set_perm(c, perm, shared, tran);
2645 ret = bdrv_refresh_perms(c->bs, tran, &local_err);
2647 tran_finalize(tran, ret);
2650 if ((perm & ~c->perm) || (c->shared_perm & ~shared)) {
2651 /* tighten permissions */
2652 error_propagate(errp, local_err);
2655 * Our caller may intend to only loosen restrictions and
2656 * does not expect this function to fail. Errors are not
2657 * fatal in such a case, so we can just hide them from our
2660 error_free(local_err);
2668 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
2670 uint64_t parent_perms, parent_shared;
2671 uint64_t perms, shared;
2673 GLOBAL_STATE_CODE();
2675 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
2676 bdrv_child_perm(bs, c->bs, c, c->role, NULL,
2677 parent_perms, parent_shared, &perms, &shared);
2679 return bdrv_child_try_set_perm(c, perms, shared, errp);
2683 * Default implementation for .bdrv_child_perm() for block filters:
2684 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the
2687 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
2689 BlockReopenQueue *reopen_queue,
2690 uint64_t perm, uint64_t shared,
2691 uint64_t *nperm, uint64_t *nshared)
2693 GLOBAL_STATE_CODE();
2694 *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
2695 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
2698 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c,
2700 BlockReopenQueue *reopen_queue,
2701 uint64_t perm, uint64_t shared,
2702 uint64_t *nperm, uint64_t *nshared)
2704 assert(role & BDRV_CHILD_COW);
2705 GLOBAL_STATE_CODE();
2708 * We want consistent read from backing files if the parent needs it.
2709 * No other operations are performed on backing files.
2711 perm &= BLK_PERM_CONSISTENT_READ;
2714 * If the parent can deal with changing data, we're okay with a
2715 * writable and resizable backing file.
2716 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too?
2718 if (shared & BLK_PERM_WRITE) {
2719 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
2724 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
2726 if (bs->open_flags & BDRV_O_INACTIVE) {
2727 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2734 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c,
2736 BlockReopenQueue *reopen_queue,
2737 uint64_t perm, uint64_t shared,
2738 uint64_t *nperm, uint64_t *nshared)
2742 GLOBAL_STATE_CODE();
2743 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA));
2745 flags = bdrv_reopen_get_flags(reopen_queue, bs);
2748 * Apart from the modifications below, the same permissions are
2749 * forwarded and left alone as for filters
2751 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2752 perm, shared, &perm, &shared);
2754 if (role & BDRV_CHILD_METADATA) {
2755 /* Format drivers may touch metadata even if the guest doesn't write */
2756 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
2757 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2761 * bs->file always needs to be consistent because of the
2762 * metadata. We can never allow other users to resize or write
2765 if (!(flags & BDRV_O_NO_IO)) {
2766 perm |= BLK_PERM_CONSISTENT_READ;
2768 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
2771 if (role & BDRV_CHILD_DATA) {
2773 * Technically, everything in this block is a subset of the
2774 * BDRV_CHILD_METADATA path taken above, and so this could
2775 * be an "else if" branch. However, that is not obvious, and
2776 * this function is not performance critical, therefore we let
2777 * this be an independent "if".
2781 * We cannot allow other users to resize the file because the
2782 * format driver might have some assumptions about the size
2783 * (e.g. because it is stored in metadata, or because the file
2784 * is split into fixed-size data files).
2786 shared &= ~BLK_PERM_RESIZE;
2789 * WRITE_UNCHANGED often cannot be performed as such on the
2790 * data file. For example, the qcow2 driver may still need to
2791 * write copied clusters on copy-on-read.
2793 if (perm & BLK_PERM_WRITE_UNCHANGED) {
2794 perm |= BLK_PERM_WRITE;
2798 * If the data file is written to, the format driver may
2799 * expect to be able to resize it by writing beyond the EOF.
2801 if (perm & BLK_PERM_WRITE) {
2802 perm |= BLK_PERM_RESIZE;
2806 if (bs->open_flags & BDRV_O_INACTIVE) {
2807 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
2814 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
2815 BdrvChildRole role, BlockReopenQueue *reopen_queue,
2816 uint64_t perm, uint64_t shared,
2817 uint64_t *nperm, uint64_t *nshared)
2819 GLOBAL_STATE_CODE();
2820 if (role & BDRV_CHILD_FILTERED) {
2821 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
2823 bdrv_filter_default_perms(bs, c, role, reopen_queue,
2824 perm, shared, nperm, nshared);
2825 } else if (role & BDRV_CHILD_COW) {
2826 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA)));
2827 bdrv_default_perms_for_cow(bs, c, role, reopen_queue,
2828 perm, shared, nperm, nshared);
2829 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) {
2830 bdrv_default_perms_for_storage(bs, c, role, reopen_queue,
2831 perm, shared, nperm, nshared);
2833 g_assert_not_reached();
2837 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
2839 static const uint64_t permissions[] = {
2840 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ,
2841 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE,
2842 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED,
2843 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE,
2846 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX);
2847 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1);
2849 assert(qapi_perm < BLOCK_PERMISSION__MAX);
2851 return permissions[qapi_perm];
2855 * Replaces the node that a BdrvChild points to without updating permissions.
2857 * If @new_bs is non-NULL, the parent of @child must already be drained through
2858 * @child and the caller must hold the AioContext lock for @new_bs.
2860 static void bdrv_replace_child_noperm(BdrvChild *child,
2861 BlockDriverState *new_bs)
2863 BlockDriverState *old_bs = child->bs;
2864 int new_bs_quiesce_counter;
2866 assert(!child->frozen);
2869 * If we want to change the BdrvChild to point to a drained node as its new
2870 * child->bs, we need to make sure that its new parent is drained, too. In
2871 * other words, either child->quiesce_parent must already be true or we must
2872 * be able to set it and keep the parent's quiesce_counter consistent with
2873 * that, but without polling or starting new requests (this function
2874 * guarantees that it doesn't poll, and starting new requests would be
2875 * against the invariants of drain sections).
2877 * To keep things simple, we pick the first option (child->quiesce_parent
2878 * must already be true). We also generalise the rule a bit to make it
2879 * easier to verify in callers and more likely to be covered in test cases:
2880 * The parent must be quiesced through this child even if new_bs isn't
2881 * currently drained.
2883 * The only exception is for callers that always pass new_bs == NULL. In
2884 * this case, we obviously never need to consider the case of a drained
2885 * new_bs, so we can keep the callers simpler by allowing them not to drain
2888 assert(!new_bs || child->quiesced_parent);
2889 assert(old_bs != new_bs);
2890 GLOBAL_STATE_CODE();
2892 if (old_bs && new_bs) {
2893 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
2896 /* TODO Pull this up into the callers to avoid polling here */
2897 bdrv_graph_wrlock(new_bs);
2899 if (child->klass->detach) {
2900 child->klass->detach(child);
2902 QLIST_REMOVE(child, next_parent);
2908 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
2909 if (child->klass->attach) {
2910 child->klass->attach(child);
2913 bdrv_graph_wrunlock();
2916 * If the parent was drained through this BdrvChild previously, but new_bs
2917 * is not drained, allow requests to come in only after the new node has
2920 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0);
2921 if (!new_bs_quiesce_counter && child->quiesced_parent) {
2922 bdrv_parent_drained_end_single(child);
2927 * Free the given @child.
2929 * The child must be empty (i.e. `child->bs == NULL`) and it must be
2930 * unused (i.e. not in a children list).
2932 static void bdrv_child_free(BdrvChild *child)
2935 GLOBAL_STATE_CODE();
2936 assert(!child->next.le_prev); /* not in children list */
2938 g_free(child->name);
2942 typedef struct BdrvAttachChildCommonState {
2944 AioContext *old_parent_ctx;
2945 AioContext *old_child_ctx;
2946 } BdrvAttachChildCommonState;
2948 static void bdrv_attach_child_common_abort(void *opaque)
2950 BdrvAttachChildCommonState *s = opaque;
2951 BlockDriverState *bs = s->child->bs;
2953 GLOBAL_STATE_CODE();
2954 bdrv_replace_child_noperm(s->child, NULL);
2956 if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
2957 bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort);
2960 if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) {
2962 GHashTable *visited;
2967 /* No need to visit `child`, because it has been detached already */
2968 visited = g_hash_table_new(NULL, NULL);
2969 ret = s->child->klass->change_aio_ctx(s->child, s->old_parent_ctx,
2970 visited, tran, &error_abort);
2971 g_hash_table_destroy(visited);
2973 /* transaction is supposed to always succeed */
2974 assert(ret == true);
2979 bdrv_child_free(s->child);
2982 static TransactionActionDrv bdrv_attach_child_common_drv = {
2983 .abort = bdrv_attach_child_common_abort,
2988 * Common part of attaching bdrv child to bs or to blk or to job
2990 * Function doesn't update permissions, caller is responsible for this.
2992 * Returns new created child.
2994 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
2995 * @child_bs can move to a different AioContext in this function. Callers must
2996 * make sure that their AioContext locking is still correct after this.
2998 static BdrvChild *bdrv_attach_child_common(BlockDriverState *child_bs,
2999 const char *child_name,
3000 const BdrvChildClass *child_class,
3001 BdrvChildRole child_role,
3002 uint64_t perm, uint64_t shared_perm,
3004 Transaction *tran, Error **errp)
3006 BdrvChild *new_child;
3007 AioContext *parent_ctx, *new_child_ctx;
3008 AioContext *child_ctx = bdrv_get_aio_context(child_bs);
3010 assert(child_class->get_parent_desc);
3011 GLOBAL_STATE_CODE();
3013 new_child = g_new(BdrvChild, 1);
3014 *new_child = (BdrvChild) {
3016 .name = g_strdup(child_name),
3017 .klass = child_class,
3020 .shared_perm = shared_perm,
3025 * If the AioContexts don't match, first try to move the subtree of
3026 * child_bs into the AioContext of the new parent. If this doesn't work,
3027 * try moving the parent into the AioContext of child_bs instead.
3029 parent_ctx = bdrv_child_get_parent_aio_context(new_child);
3030 if (child_ctx != parent_ctx) {
3031 Error *local_err = NULL;
3032 int ret = bdrv_try_change_aio_context(child_bs, parent_ctx, NULL,
3035 if (ret < 0 && child_class->change_aio_ctx) {
3036 Transaction *tran = tran_new();
3037 GHashTable *visited = g_hash_table_new(NULL, NULL);
3040 g_hash_table_add(visited, new_child);
3041 ret_child = child_class->change_aio_ctx(new_child, child_ctx,
3042 visited, tran, NULL);
3043 if (ret_child == true) {
3044 error_free(local_err);
3047 tran_finalize(tran, ret_child == true ? 0 : -1);
3048 g_hash_table_destroy(visited);
3052 error_propagate(errp, local_err);
3053 bdrv_child_free(new_child);
3058 new_child_ctx = bdrv_get_aio_context(child_bs);
3059 if (new_child_ctx != child_ctx) {
3060 aio_context_release(child_ctx);
3061 aio_context_acquire(new_child_ctx);
3066 * Let every new BdrvChild start with a drained parent. Inserting the child
3067 * in the graph with bdrv_replace_child_noperm() will undrain it if
3068 * @child_bs is not drained.
3070 * The child was only just created and is not yet visible in global state
3071 * until bdrv_replace_child_noperm() inserts it into the graph, so nobody
3072 * could have sent requests and polling is not necessary.
3074 * Note that this means that the parent isn't fully drained yet, we only
3075 * stop new requests from coming in. This is fine, we don't care about the
3076 * old requests here, they are not for this child. If another place enters a
3077 * drain section for the same parent, but wants it to be fully quiesced, it
3078 * will not run most of the the code in .drained_begin() again (which is not
3079 * a problem, we already did this), but it will still poll until the parent
3080 * is fully quiesced, so it will not be negatively affected either.
3082 bdrv_parent_drained_begin_single(new_child);
3083 bdrv_replace_child_noperm(new_child, child_bs);
3085 BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
3086 *s = (BdrvAttachChildCommonState) {
3088 .old_parent_ctx = parent_ctx,
3089 .old_child_ctx = child_ctx,
3091 tran_add(tran, &bdrv_attach_child_common_drv, s);
3093 if (new_child_ctx != child_ctx) {
3094 aio_context_release(new_child_ctx);
3095 aio_context_acquire(child_ctx);
3102 * Function doesn't update permissions, caller is responsible for this.
3104 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
3105 * @child_bs can move to a different AioContext in this function. Callers must
3106 * make sure that their AioContext locking is still correct after this.
3108 static BdrvChild *bdrv_attach_child_noperm(BlockDriverState *parent_bs,
3109 BlockDriverState *child_bs,
3110 const char *child_name,
3111 const BdrvChildClass *child_class,
3112 BdrvChildRole child_role,
3116 uint64_t perm, shared_perm;
3118 assert(parent_bs->drv);
3119 GLOBAL_STATE_CODE();
3121 if (bdrv_recurse_has_child(child_bs, parent_bs)) {
3122 error_setg(errp, "Making '%s' a %s child of '%s' would create a cycle",
3123 child_bs->node_name, child_name, parent_bs->node_name);
3127 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
3128 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
3129 perm, shared_perm, &perm, &shared_perm);
3131 return bdrv_attach_child_common(child_bs, child_name, child_class,
3132 child_role, perm, shared_perm, parent_bs,
3137 * This function steals the reference to child_bs from the caller.
3138 * That reference is later dropped by bdrv_root_unref_child().
3140 * On failure NULL is returned, errp is set and the reference to
3141 * child_bs is also dropped.
3143 * The caller must hold the AioContext lock @child_bs, but not that of @ctx
3144 * (unless @child_bs is already in @ctx).
3146 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
3147 const char *child_name,
3148 const BdrvChildClass *child_class,
3149 BdrvChildRole child_role,
3150 uint64_t perm, uint64_t shared_perm,
3151 void *opaque, Error **errp)
3155 Transaction *tran = tran_new();
3157 GLOBAL_STATE_CODE();
3159 child = bdrv_attach_child_common(child_bs, child_name, child_class,
3160 child_role, perm, shared_perm, opaque,
3167 ret = bdrv_refresh_perms(child_bs, tran, errp);
3170 tran_finalize(tran, ret);
3172 bdrv_unref(child_bs);
3174 return ret < 0 ? NULL : child;
3178 * This function transfers the reference to child_bs from the caller
3179 * to parent_bs. That reference is later dropped by parent_bs on
3180 * bdrv_close() or if someone calls bdrv_unref_child().
3182 * On failure NULL is returned, errp is set and the reference to
3183 * child_bs is also dropped.
3185 * If @parent_bs and @child_bs are in different AioContexts, the caller must
3186 * hold the AioContext lock for @child_bs, but not for @parent_bs.
3188 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
3189 BlockDriverState *child_bs,
3190 const char *child_name,
3191 const BdrvChildClass *child_class,
3192 BdrvChildRole child_role,
3197 Transaction *tran = tran_new();
3199 GLOBAL_STATE_CODE();
3201 child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name,
3202 child_class, child_role, tran, errp);
3208 ret = bdrv_refresh_perms(parent_bs, tran, errp);
3214 tran_finalize(tran, ret);
3216 bdrv_unref(child_bs);
3218 return ret < 0 ? NULL : child;
3221 /* Callers must ensure that child->frozen is false. */
3222 void bdrv_root_unref_child(BdrvChild *child)
3224 BlockDriverState *child_bs = child->bs;
3226 GLOBAL_STATE_CODE();
3227 bdrv_replace_child_noperm(child, NULL);
3228 bdrv_child_free(child);
3232 * Update permissions for old node. We're just taking a parent away, so
3233 * we're loosening restrictions. Errors of permission update are not
3234 * fatal in this case, ignore them.
3236 bdrv_refresh_perms(child_bs, NULL, NULL);
3239 * When the parent requiring a non-default AioContext is removed, the
3240 * node moves back to the main AioContext
3242 bdrv_try_change_aio_context(child_bs, qemu_get_aio_context(), NULL,
3246 bdrv_unref(child_bs);
3249 typedef struct BdrvSetInheritsFrom {
3250 BlockDriverState *bs;
3251 BlockDriverState *old_inherits_from;
3252 } BdrvSetInheritsFrom;
3254 static void bdrv_set_inherits_from_abort(void *opaque)
3256 BdrvSetInheritsFrom *s = opaque;
3258 s->bs->inherits_from = s->old_inherits_from;
3261 static TransactionActionDrv bdrv_set_inherits_from_drv = {
3262 .abort = bdrv_set_inherits_from_abort,
3266 /* @tran is allowed to be NULL. In this case no rollback is possible */
3267 static void bdrv_set_inherits_from(BlockDriverState *bs,
3268 BlockDriverState *new_inherits_from,
3272 BdrvSetInheritsFrom *s = g_new(BdrvSetInheritsFrom, 1);
3274 *s = (BdrvSetInheritsFrom) {
3276 .old_inherits_from = bs->inherits_from,
3279 tran_add(tran, &bdrv_set_inherits_from_drv, s);
3282 bs->inherits_from = new_inherits_from;
3286 * Clear all inherits_from pointers from children and grandchildren of
3287 * @root that point to @root, where necessary.
3288 * @tran is allowed to be NULL. In this case no rollback is possible
3290 static void bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child,
3295 if (child->bs->inherits_from == root) {
3297 * Remove inherits_from only when the last reference between root and
3298 * child->bs goes away.
3300 QLIST_FOREACH(c, &root->children, next) {
3301 if (c != child && c->bs == child->bs) {
3306 bdrv_set_inherits_from(child->bs, NULL, tran);
3310 QLIST_FOREACH(c, &child->bs->children, next) {
3311 bdrv_unset_inherits_from(root, c, tran);
3315 /* Callers must ensure that child->frozen is false. */
3316 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
3318 GLOBAL_STATE_CODE();
3319 if (child == NULL) {
3323 bdrv_unset_inherits_from(parent, child, NULL);
3324 bdrv_root_unref_child(child);
3328 static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
3331 GLOBAL_STATE_CODE();
3332 QLIST_FOREACH(c, &bs->parents, next_parent) {
3333 if (c->klass->change_media) {
3334 c->klass->change_media(c, load);
3339 /* Return true if you can reach parent going through child->inherits_from
3340 * recursively. If parent or child are NULL, return false */
3341 static bool bdrv_inherits_from_recursive(BlockDriverState *child,
3342 BlockDriverState *parent)
3344 while (child && child != parent) {
3345 child = child->inherits_from;
3348 return child != NULL;
3352 * Return the BdrvChildRole for @bs's backing child. bs->backing is
3353 * mostly used for COW backing children (role = COW), but also for
3354 * filtered children (role = FILTERED | PRIMARY).
3356 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
3358 if (bs->drv && bs->drv->is_filter) {
3359 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
3361 return BDRV_CHILD_COW;
3366 * Sets the bs->backing or bs->file link of a BDS. A new reference is created;
3367 * callers which don't need their own reference any more must call bdrv_unref().
3369 * Function doesn't update permissions, caller is responsible for this.
3371 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
3372 * @child_bs can move to a different AioContext in this function. Callers must
3373 * make sure that their AioContext locking is still correct after this.
3375 static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
3376 BlockDriverState *child_bs,
3378 Transaction *tran, Error **errp)
3380 bool update_inherits_from =
3381 bdrv_inherits_from_recursive(child_bs, parent_bs);
3382 BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file;
3385 GLOBAL_STATE_CODE();
3387 if (!parent_bs->drv) {
3389 * Node without drv is an object without a class :/. TODO: finally fix
3390 * qcow2 driver to never clear bs->drv and implement format corruption
3391 * handling in other way.
3393 error_setg(errp, "Node corrupted");
3397 if (child && child->frozen) {
3398 error_setg(errp, "Cannot change frozen '%s' link from '%s' to '%s'",
3399 child->name, parent_bs->node_name, child->bs->node_name);
3403 if (is_backing && !parent_bs->drv->is_filter &&
3404 !parent_bs->drv->supports_backing)
3406 error_setg(errp, "Driver '%s' of node '%s' does not support backing "
3407 "files", parent_bs->drv->format_name, parent_bs->node_name);
3411 if (parent_bs->drv->is_filter) {
3412 role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
3413 } else if (is_backing) {
3414 role = BDRV_CHILD_COW;
3417 * We only can use same role as it is in existing child. We don't have
3418 * infrastructure to determine role of file child in generic way
3421 error_setg(errp, "Cannot set file child to format node without "
3429 bdrv_unset_inherits_from(parent_bs, child, tran);
3430 bdrv_remove_child(child, tran);
3437 child = bdrv_attach_child_noperm(parent_bs, child_bs,
3438 is_backing ? "backing" : "file",
3439 &child_of_bds, role,
3447 * If inherits_from pointed recursively to bs then let's update it to
3448 * point directly to bs (else it will become NULL).
3450 if (update_inherits_from) {
3451 bdrv_set_inherits_from(child_bs, parent_bs, tran);
3455 bdrv_graph_rdlock_main_loop();
3456 bdrv_refresh_limits(parent_bs, tran, NULL);
3457 bdrv_graph_rdunlock_main_loop();
3463 * The caller must hold the AioContext lock for @backing_hd. Both @bs and
3464 * @backing_hd can move to a different AioContext in this function. Callers must
3465 * make sure that their AioContext locking is still correct after this.
3467 static int bdrv_set_backing_noperm(BlockDriverState *bs,
3468 BlockDriverState *backing_hd,
3469 Transaction *tran, Error **errp)
3471 GLOBAL_STATE_CODE();
3472 return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp);
3475 int bdrv_set_backing_hd_drained(BlockDriverState *bs,
3476 BlockDriverState *backing_hd,
3480 Transaction *tran = tran_new();
3482 GLOBAL_STATE_CODE();
3483 assert(bs->quiesce_counter > 0);
3485 ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
3490 ret = bdrv_refresh_perms(bs, tran, errp);
3492 tran_finalize(tran, ret);
3496 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
3500 GLOBAL_STATE_CODE();
3502 bdrv_drained_begin(bs);
3503 ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp);
3504 bdrv_drained_end(bs);
3510 * Opens the backing file for a BlockDriverState if not yet open
3512 * bdref_key specifies the key for the image's BlockdevRef in the options QDict.
3513 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3514 * itself, all options starting with "${bdref_key}." are considered part of the
3517 * The caller must hold the main AioContext lock.
3519 * TODO Can this be unified with bdrv_open_image()?
3521 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
3522 const char *bdref_key, Error **errp)
3524 char *backing_filename = NULL;
3525 char *bdref_key_dot;
3526 const char *reference = NULL;
3528 bool implicit_backing = false;
3529 BlockDriverState *backing_hd;
3530 AioContext *backing_hd_ctx;
3532 QDict *tmp_parent_options = NULL;
3533 Error *local_err = NULL;
3535 GLOBAL_STATE_CODE();
3537 if (bs->backing != NULL) {
3541 /* NULL means an empty set of options */
3542 if (parent_options == NULL) {
3543 tmp_parent_options = qdict_new();
3544 parent_options = tmp_parent_options;
3547 bs->open_flags &= ~BDRV_O_NO_BACKING;
3549 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3550 qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
3551 g_free(bdref_key_dot);
3554 * Caution: while qdict_get_try_str() is fine, getting non-string
3555 * types would require more care. When @parent_options come from
3556 * -blockdev or blockdev_add, its members are typed according to
3557 * the QAPI schema, but when they come from -drive, they're all
3560 reference = qdict_get_try_str(parent_options, bdref_key);
3561 if (reference || qdict_haskey(options, "file.filename")) {
3562 /* keep backing_filename NULL */
3563 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
3564 qobject_unref(options);
3567 if (qdict_size(options) == 0) {
3568 /* If the user specifies options that do not modify the
3569 * backing file's behavior, we might still consider it the
3570 * implicit backing file. But it's easier this way, and
3571 * just specifying some of the backing BDS's options is
3572 * only possible with -drive anyway (otherwise the QAPI
3573 * schema forces the user to specify everything). */
3574 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
3577 backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
3580 error_propagate(errp, local_err);
3581 qobject_unref(options);
3586 if (!bs->drv || !bs->drv->supports_backing) {
3588 error_setg(errp, "Driver doesn't support backing files");
3589 qobject_unref(options);
3594 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
3595 qdict_put_str(options, "driver", bs->backing_format);
3598 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
3599 &child_of_bds, bdrv_backing_role(bs), errp);
3601 bs->open_flags |= BDRV_O_NO_BACKING;
3602 error_prepend(errp, "Could not open backing file: ");
3607 if (implicit_backing) {
3608 bdrv_refresh_filename(backing_hd);
3609 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
3610 backing_hd->filename);
3613 /* Hook up the backing file link; drop our reference, bs owns the
3614 * backing_hd reference now */
3615 backing_hd_ctx = bdrv_get_aio_context(backing_hd);
3616 aio_context_acquire(backing_hd_ctx);
3617 ret = bdrv_set_backing_hd(bs, backing_hd, errp);
3618 bdrv_unref(backing_hd);
3619 aio_context_release(backing_hd_ctx);
3625 qdict_del(parent_options, bdref_key);
3628 g_free(backing_filename);
3629 qobject_unref(tmp_parent_options);
3633 static BlockDriverState *
3634 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
3635 BlockDriverState *parent, const BdrvChildClass *child_class,
3636 BdrvChildRole child_role, bool allow_none, Error **errp)
3638 BlockDriverState *bs = NULL;
3639 QDict *image_options;
3640 char *bdref_key_dot;
3641 const char *reference;
3643 assert(child_class != NULL);
3645 bdref_key_dot = g_strdup_printf("%s.", bdref_key);
3646 qdict_extract_subqdict(options, &image_options, bdref_key_dot);
3647 g_free(bdref_key_dot);
3650 * Caution: while qdict_get_try_str() is fine, getting non-string
3651 * types would require more care. When @options come from
3652 * -blockdev or blockdev_add, its members are typed according to
3653 * the QAPI schema, but when they come from -drive, they're all
3656 reference = qdict_get_try_str(options, bdref_key);
3657 if (!filename && !reference && !qdict_size(image_options)) {
3659 error_setg(errp, "A block device must be specified for \"%s\"",
3662 qobject_unref(image_options);
3666 bs = bdrv_open_inherit(filename, reference, image_options, 0,
3667 parent, child_class, child_role, errp);
3673 qdict_del(options, bdref_key);
3678 * Opens a disk image whose options are given as BlockdevRef in another block
3681 * If allow_none is true, no image will be opened if filename is false and no
3682 * BlockdevRef is given. NULL will be returned, but errp remains unset.
3684 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
3685 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
3686 * itself, all options starting with "${bdref_key}." are considered part of the
3689 * The BlockdevRef will be removed from the options QDict.
3691 * The caller must hold the lock of the main AioContext and no other AioContext.
3692 * @parent can move to a different AioContext in this function. Callers must
3693 * make sure that their AioContext locking is still correct after this.
3695 BdrvChild *bdrv_open_child(const char *filename,
3696 QDict *options, const char *bdref_key,
3697 BlockDriverState *parent,
3698 const BdrvChildClass *child_class,
3699 BdrvChildRole child_role,
3700 bool allow_none, Error **errp)
3702 BlockDriverState *bs;
3706 GLOBAL_STATE_CODE();
3708 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
3709 child_role, allow_none, errp);
3714 ctx = bdrv_get_aio_context(bs);
3715 aio_context_acquire(ctx);
3716 child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
3718 aio_context_release(ctx);
3724 * Wrapper on bdrv_open_child() for most popular case: open primary child of bs.
3726 * The caller must hold the lock of the main AioContext and no other AioContext.
3727 * @parent can move to a different AioContext in this function. Callers must
3728 * make sure that their AioContext locking is still correct after this.
3730 int bdrv_open_file_child(const char *filename,
3731 QDict *options, const char *bdref_key,
3732 BlockDriverState *parent, Error **errp)
3736 /* commit_top and mirror_top don't use this function */
3737 assert(!parent->drv->filtered_child_is_backing);
3738 role = parent->drv->is_filter ?
3739 (BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE;
3741 if (!bdrv_open_child(filename, options, bdref_key, parent,
3742 &child_of_bds, role, false, errp))
3751 * TODO Future callers may need to specify parent/child_class in order for
3752 * option inheritance to work. Existing callers use it for the root node.
3754 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
3756 BlockDriverState *bs = NULL;
3757 QObject *obj = NULL;
3758 QDict *qdict = NULL;
3759 const char *reference = NULL;
3762 GLOBAL_STATE_CODE();
3764 if (ref->type == QTYPE_QSTRING) {
3765 reference = ref->u.reference;
3767 BlockdevOptions *options = &ref->u.definition;
3768 assert(ref->type == QTYPE_QDICT);
3770 v = qobject_output_visitor_new(&obj);
3771 visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
3772 visit_complete(v, &obj);
3774 qdict = qobject_to(QDict, obj);
3775 qdict_flatten(qdict);
3777 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for
3778 * compatibility with other callers) rather than what we want as the
3779 * real defaults. Apply the defaults here instead. */
3780 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
3781 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
3782 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
3783 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
3787 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp);
3794 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
3796 QDict *snapshot_options,
3799 g_autofree char *tmp_filename = NULL;
3801 QemuOpts *opts = NULL;
3802 BlockDriverState *bs_snapshot = NULL;
3803 AioContext *ctx = bdrv_get_aio_context(bs);
3806 GLOBAL_STATE_CODE();
3808 /* if snapshot, we create a temporary backing file and open it
3809 instead of opening 'filename' directly */
3811 /* Get the required size from the image */
3812 aio_context_acquire(ctx);
3813 total_size = bdrv_getlength(bs);
3814 aio_context_release(ctx);
3816 if (total_size < 0) {
3817 error_setg_errno(errp, -total_size, "Could not get image size");
3821 /* Create the temporary image */
3822 tmp_filename = create_tmp_file(errp);
3823 if (!tmp_filename) {
3827 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
3829 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
3830 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
3831 qemu_opts_del(opts);
3833 error_prepend(errp, "Could not create temporary overlay '%s': ",
3838 /* Prepare options QDict for the temporary file */
3839 qdict_put_str(snapshot_options, "file.driver", "file");
3840 qdict_put_str(snapshot_options, "file.filename", tmp_filename);
3841 qdict_put_str(snapshot_options, "driver", "qcow2");
3843 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
3844 snapshot_options = NULL;
3849 aio_context_acquire(ctx);
3850 ret = bdrv_append(bs_snapshot, bs, errp);
3851 aio_context_release(ctx);
3859 qobject_unref(snapshot_options);
3864 * Opens a disk image (raw, qcow2, vmdk, ...)
3866 * options is a QDict of options to pass to the block drivers, or NULL for an
3867 * empty set of options. The reference to the QDict belongs to the block layer
3868 * after the call (even on failure), so if the caller intends to reuse the
3869 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
3871 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
3872 * If it is not NULL, the referenced BDS will be reused.
3874 * The reference parameter may be used to specify an existing block device which
3875 * should be opened. If specified, neither options nor a filename may be given,
3876 * nor can an existing BDS be reused (that is, *pbs has to be NULL).
3878 * The caller must always hold the main AioContext lock.
3880 static BlockDriverState * no_coroutine_fn
3881 bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
3882 int flags, BlockDriverState *parent,
3883 const BdrvChildClass *child_class, BdrvChildRole child_role,
3887 BlockBackend *file = NULL;
3888 BlockDriverState *bs;
3889 BlockDriver *drv = NULL;
3891 const char *drvname;
3892 const char *backing;
3893 Error *local_err = NULL;
3894 QDict *snapshot_options = NULL;
3895 int snapshot_flags = 0;
3896 AioContext *ctx = qemu_get_aio_context();
3898 assert(!child_class || !flags);
3899 assert(!child_class == !parent);
3900 GLOBAL_STATE_CODE();
3901 assert(!qemu_in_coroutine());
3904 bool options_non_empty = options ? qdict_size(options) : false;
3905 qobject_unref(options);
3907 if (filename || options_non_empty) {
3908 error_setg(errp, "Cannot reference an existing block device with "
3909 "additional options or a new filename");
3913 bs = bdrv_lookup_bs(reference, reference, errp);
3924 /* NULL means an empty set of options */
3925 if (options == NULL) {
3926 options = qdict_new();
3929 /* json: syntax counts as explicit options, as if in the QDict */
3930 parse_json_protocol(options, &filename, &local_err);
3935 bs->explicit_options = qdict_clone_shallow(options);
3938 bool parent_is_format;
3941 parent_is_format = parent->drv->is_format;
3944 * parent->drv is not set yet because this node is opened for
3945 * (potential) format probing. That means that @parent is going
3946 * to be a format node.
3948 parent_is_format = true;
3951 bs->inherits_from = parent;
3952 child_class->inherit_options(child_role, parent_is_format,
3954 parent->open_flags, parent->options);
3957 ret = bdrv_fill_options(&options, filename, &flags, &local_err);
3963 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
3964 * Caution: getting a boolean member of @options requires care.
3965 * When @options come from -blockdev or blockdev_add, members are
3966 * typed according to the QAPI schema, but when they come from
3967 * -drive, they're all QString.
3969 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
3970 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
3971 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
3973 flags &= ~BDRV_O_RDWR;
3976 if (flags & BDRV_O_SNAPSHOT) {
3977 snapshot_options = qdict_new();
3978 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options,
3980 /* Let bdrv_backing_options() override "read-only" */
3981 qdict_del(options, BDRV_OPT_READ_ONLY);
3982 bdrv_inherited_options(BDRV_CHILD_COW, true,
3983 &flags, options, flags, options);
3986 bs->open_flags = flags;
3987 bs->options = options;
3988 options = qdict_clone_shallow(options);
3990 /* Find the right image format driver */
3991 /* See cautionary note on accessing @options above */
3992 drvname = qdict_get_try_str(options, "driver");
3994 drv = bdrv_find_format(drvname);
3996 error_setg(errp, "Unknown driver: '%s'", drvname);
4001 assert(drvname || !(flags & BDRV_O_PROTOCOL));
4003 /* See cautionary note on accessing @options above */
4004 backing = qdict_get_try_str(options, "backing");
4005 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
4006 (backing && *backing == '\0'))
4009 warn_report("Use of \"backing\": \"\" is deprecated; "
4010 "use \"backing\": null instead");
4012 flags |= BDRV_O_NO_BACKING;
4013 qdict_del(bs->explicit_options, "backing");
4014 qdict_del(bs->options, "backing");
4015 qdict_del(options, "backing");
4018 /* Open image file without format layer. This BlockBackend is only used for
4019 * probing, the block drivers will do their own bdrv_open_child() for the
4020 * same BDS, which is why we put the node name back into options. */
4021 if ((flags & BDRV_O_PROTOCOL) == 0) {
4022 BlockDriverState *file_bs;
4024 file_bs = bdrv_open_child_bs(filename, options, "file", bs,
4025 &child_of_bds, BDRV_CHILD_IMAGE,
4030 if (file_bs != NULL) {
4031 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only
4032 * looking at the header to guess the image format. This works even
4033 * in cases where a guest would not see a consistent state. */
4034 ctx = bdrv_get_aio_context(file_bs);
4035 aio_context_acquire(ctx);
4036 file = blk_new(ctx, 0, BLK_PERM_ALL);
4037 blk_insert_bs(file, file_bs, &local_err);
4038 bdrv_unref(file_bs);
4039 aio_context_release(ctx);
4045 qdict_put_str(options, "file", bdrv_get_node_name(file_bs));
4049 /* Image format probing */
4052 ret = find_image_format(file, filename, &drv, &local_err);
4057 * This option update would logically belong in bdrv_fill_options(),
4058 * but we first need to open bs->file for the probing to work, while
4059 * opening bs->file already requires the (mostly) final set of options
4060 * so that cache mode etc. can be inherited.
4062 * Adding the driver later is somewhat ugly, but it's not an option
4063 * that would ever be inherited, so it's correct. We just need to make
4064 * sure to update both bs->options (which has the full effective
4065 * options for bs) and options (which has file.* already removed).
4067 qdict_put_str(bs->options, "driver", drv->format_name);
4068 qdict_put_str(options, "driver", drv->format_name);
4070 error_setg(errp, "Must specify either driver or file");
4074 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
4075 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
4076 /* file must be NULL if a protocol BDS is about to be created
4077 * (the inverse results in an error message from bdrv_open_common()) */
4078 assert(!(flags & BDRV_O_PROTOCOL) || !file);
4080 /* Open the image */
4081 ret = bdrv_open_common(bs, file, options, &local_err);
4086 /* The AioContext could have changed during bdrv_open_common() */
4087 ctx = bdrv_get_aio_context(bs);
4090 aio_context_acquire(ctx);
4092 aio_context_release(ctx);
4096 /* If there is a backing file, use it */
4097 if ((flags & BDRV_O_NO_BACKING) == 0) {
4098 ret = bdrv_open_backing_file(bs, options, "backing", &local_err);
4100 goto close_and_fail;
4104 /* Remove all children options and references
4105 * from bs->options and bs->explicit_options */
4106 QLIST_FOREACH(child, &bs->children, next) {
4107 char *child_key_dot;
4108 child_key_dot = g_strdup_printf("%s.", child->name);
4109 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot);
4110 qdict_extract_subqdict(bs->options, NULL, child_key_dot);
4111 qdict_del(bs->explicit_options, child->name);
4112 qdict_del(bs->options, child->name);
4113 g_free(child_key_dot);
4116 /* Check if any unknown options were used */
4117 if (qdict_size(options) != 0) {
4118 const QDictEntry *entry = qdict_first(options);
4119 if (flags & BDRV_O_PROTOCOL) {
4120 error_setg(errp, "Block protocol '%s' doesn't support the option "
4121 "'%s'", drv->format_name, entry->key);
4124 "Block format '%s' does not support the option '%s'",
4125 drv->format_name, entry->key);
4128 goto close_and_fail;
4131 bdrv_parent_cb_change_media(bs, true);
4133 qobject_unref(options);
4136 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the
4137 * temporary snapshot afterwards. */
4138 if (snapshot_flags) {
4139 BlockDriverState *snapshot_bs;
4140 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags,
4141 snapshot_options, &local_err);
4142 snapshot_options = NULL;
4144 goto close_and_fail;
4146 /* We are not going to return bs but the overlay on top of it
4147 * (snapshot_bs); thus, we have to drop the strong reference to bs
4148 * (which we obtained by calling bdrv_new()). bs will not be deleted,
4149 * though, because the overlay still has a reference to it. */
4150 aio_context_acquire(ctx);
4152 aio_context_release(ctx);
4159 aio_context_acquire(ctx);
4161 qobject_unref(snapshot_options);
4162 qobject_unref(bs->explicit_options);
4163 qobject_unref(bs->options);
4164 qobject_unref(options);
4166 bs->explicit_options = NULL;
4168 aio_context_release(ctx);
4169 error_propagate(errp, local_err);
4173 aio_context_acquire(ctx);
4175 aio_context_release(ctx);
4176 qobject_unref(snapshot_options);
4177 qobject_unref(options);
4178 error_propagate(errp, local_err);
4182 /* The caller must always hold the main AioContext lock. */
4183 BlockDriverState *bdrv_open(const char *filename, const char *reference,
4184 QDict *options, int flags, Error **errp)
4186 GLOBAL_STATE_CODE();
4188 return bdrv_open_inherit(filename, reference, options, flags, NULL,
4192 /* Return true if the NULL-terminated @list contains @str */
4193 static bool is_str_in_list(const char *str, const char *const *list)
4197 for (i = 0; list[i] != NULL; i++) {
4198 if (!strcmp(str, list[i])) {
4207 * Check that every option set in @bs->options is also set in
4210 * Options listed in the common_options list and in
4211 * @bs->drv->mutable_opts are skipped.
4213 * Return 0 on success, otherwise return -EINVAL and set @errp.
4215 static int bdrv_reset_options_allowed(BlockDriverState *bs,
4216 const QDict *new_opts, Error **errp)
4218 const QDictEntry *e;
4219 /* These options are common to all block drivers and are handled
4220 * in bdrv_reopen_prepare() so they can be left out of @new_opts */
4221 const char *const common_options[] = {
4222 "node-name", "discard", "cache.direct", "cache.no-flush",
4223 "read-only", "auto-read-only", "detect-zeroes", NULL
4226 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) {
4227 if (!qdict_haskey(new_opts, e->key) &&
4228 !is_str_in_list(e->key, common_options) &&
4229 !is_str_in_list(e->key, bs->drv->mutable_opts)) {
4230 error_setg(errp, "Option '%s' cannot be reset "
4231 "to its default value", e->key);
4240 * Returns true if @child can be reached recursively from @bs
4242 static bool bdrv_recurse_has_child(BlockDriverState *bs,
4243 BlockDriverState *child)
4251 QLIST_FOREACH(c, &bs->children, next) {
4252 if (bdrv_recurse_has_child(c->bs, child)) {
4261 * Adds a BlockDriverState to a simple queue for an atomic, transactional
4262 * reopen of multiple devices.
4264 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT
4265 * already performed, or alternatively may be NULL a new BlockReopenQueue will
4266 * be created and initialized. This newly created BlockReopenQueue should be
4267 * passed back in for subsequent calls that are intended to be of the same
4270 * bs is the BlockDriverState to add to the reopen queue.
4272 * options contains the changed options for the associated bs
4273 * (the BlockReopenQueue takes ownership)
4275 * flags contains the open flags for the associated bs
4277 * returns a pointer to bs_queue, which is either the newly allocated
4278 * bs_queue, or the existing bs_queue being used.
4280 * bs is drained here and undrained by bdrv_reopen_queue_free().
4282 * To be called with bs->aio_context locked.
4284 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
4285 BlockDriverState *bs,
4287 const BdrvChildClass *klass,
4289 bool parent_is_format,
4290 QDict *parent_options,
4296 BlockReopenQueueEntry *bs_entry;
4298 QDict *old_options, *explicit_options, *options_copy;
4302 GLOBAL_STATE_CODE();
4304 bdrv_drained_begin(bs);
4306 if (bs_queue == NULL) {
4307 bs_queue = g_new0(BlockReopenQueue, 1);
4308 QTAILQ_INIT(bs_queue);
4312 options = qdict_new();
4315 /* Check if this BlockDriverState is already in the queue */
4316 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4317 if (bs == bs_entry->state.bs) {
4323 * Precedence of options:
4324 * 1. Explicitly passed in options (highest)
4325 * 2. Retained from explicitly set options of bs
4326 * 3. Inherited from parent node
4327 * 4. Retained from effective options of bs
4330 /* Old explicitly set values (don't overwrite by inherited value) */
4331 if (bs_entry || keep_old_opts) {
4332 old_options = qdict_clone_shallow(bs_entry ?
4333 bs_entry->state.explicit_options :
4334 bs->explicit_options);
4335 bdrv_join_options(bs, options, old_options);
4336 qobject_unref(old_options);
4339 explicit_options = qdict_clone_shallow(options);
4341 /* Inherit from parent node */
4342 if (parent_options) {
4344 klass->inherit_options(role, parent_is_format, &flags, options,
4345 parent_flags, parent_options);
4347 flags = bdrv_get_flags(bs);
4350 if (keep_old_opts) {
4351 /* Old values are used for options that aren't set yet */
4352 old_options = qdict_clone_shallow(bs->options);
4353 bdrv_join_options(bs, options, old_options);
4354 qobject_unref(old_options);
4357 /* We have the final set of options so let's update the flags */
4358 options_copy = qdict_clone_shallow(options);
4359 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4360 qemu_opts_absorb_qdict(opts, options_copy, NULL);
4361 update_flags_from_options(&flags, opts);
4362 qemu_opts_del(opts);
4363 qobject_unref(options_copy);
4365 /* bdrv_open_inherit() sets and clears some additional flags internally */
4366 flags &= ~BDRV_O_PROTOCOL;
4367 if (flags & BDRV_O_RDWR) {
4368 flags |= BDRV_O_ALLOW_RDWR;
4372 bs_entry = g_new0(BlockReopenQueueEntry, 1);
4373 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry);
4375 qobject_unref(bs_entry->state.options);
4376 qobject_unref(bs_entry->state.explicit_options);
4379 bs_entry->state.bs = bs;
4380 bs_entry->state.options = options;
4381 bs_entry->state.explicit_options = explicit_options;
4382 bs_entry->state.flags = flags;
4385 * If keep_old_opts is false then it means that unspecified
4386 * options must be reset to their original value. We don't allow
4387 * resetting 'backing' but we need to know if the option is
4388 * missing in order to decide if we have to return an error.
4390 if (!keep_old_opts) {
4391 bs_entry->state.backing_missing =
4392 !qdict_haskey(options, "backing") &&
4393 !qdict_haskey(options, "backing.driver");
4396 QLIST_FOREACH(child, &bs->children, next) {
4397 QDict *new_child_options = NULL;
4398 bool child_keep_old = keep_old_opts;
4400 /* reopen can only change the options of block devices that were
4401 * implicitly created and inherited options. For other (referenced)
4402 * block devices, a syntax like "backing.foo" results in an error. */
4403 if (child->bs->inherits_from != bs) {
4407 /* Check if the options contain a child reference */
4408 if (qdict_haskey(options, child->name)) {
4409 const char *childref = qdict_get_try_str(options, child->name);
4411 * The current child must not be reopened if the child
4412 * reference is null or points to a different node.
4414 if (g_strcmp0(childref, child->bs->node_name)) {
4418 * If the child reference points to the current child then
4419 * reopen it with its existing set of options (note that
4420 * it can still inherit new options from the parent).
4422 child_keep_old = true;
4424 /* Extract child options ("child-name.*") */
4425 char *child_key_dot = g_strdup_printf("%s.", child->name);
4426 qdict_extract_subqdict(explicit_options, NULL, child_key_dot);
4427 qdict_extract_subqdict(options, &new_child_options, child_key_dot);
4428 g_free(child_key_dot);
4431 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
4432 child->klass, child->role, bs->drv->is_format,
4433 options, flags, child_keep_old);
4439 /* To be called with bs->aio_context locked */
4440 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
4441 BlockDriverState *bs,
4442 QDict *options, bool keep_old_opts)
4444 GLOBAL_STATE_CODE();
4446 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false,
4447 NULL, 0, keep_old_opts);
4450 void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue)
4452 GLOBAL_STATE_CODE();
4454 BlockReopenQueueEntry *bs_entry, *next;
4455 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
4456 AioContext *ctx = bdrv_get_aio_context(bs_entry->state.bs);
4458 aio_context_acquire(ctx);
4459 bdrv_drained_end(bs_entry->state.bs);
4460 aio_context_release(ctx);
4462 qobject_unref(bs_entry->state.explicit_options);
4463 qobject_unref(bs_entry->state.options);
4471 * Reopen multiple BlockDriverStates atomically & transactionally.
4473 * The queue passed in (bs_queue) must have been built up previous
4474 * via bdrv_reopen_queue().
4476 * Reopens all BDS specified in the queue, with the appropriate
4477 * flags. All devices are prepared for reopen, and failure of any
4478 * device will cause all device changes to be abandoned, and intermediate
4481 * If all devices prepare successfully, then the changes are committed
4484 * All affected nodes must be drained between bdrv_reopen_queue() and
4485 * bdrv_reopen_multiple().
4487 * To be called from the main thread, with all other AioContexts unlocked.
4489 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
4492 BlockReopenQueueEntry *bs_entry, *next;
4494 Transaction *tran = tran_new();
4495 g_autoptr(GSList) refresh_list = NULL;
4497 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
4498 assert(bs_queue != NULL);
4499 GLOBAL_STATE_CODE();
4501 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4502 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4503 aio_context_acquire(ctx);
4504 ret = bdrv_flush(bs_entry->state.bs);
4505 aio_context_release(ctx);
4507 error_setg_errno(errp, -ret, "Error flushing drive");
4512 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4513 assert(bs_entry->state.bs->quiesce_counter > 0);
4514 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4515 aio_context_acquire(ctx);
4516 ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp);
4517 aio_context_release(ctx);
4521 bs_entry->prepared = true;
4524 QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
4525 BDRVReopenState *state = &bs_entry->state;
4527 refresh_list = g_slist_prepend(refresh_list, state->bs);
4528 if (state->old_backing_bs) {
4529 refresh_list = g_slist_prepend(refresh_list, state->old_backing_bs);
4531 if (state->old_file_bs) {
4532 refresh_list = g_slist_prepend(refresh_list, state->old_file_bs);
4537 * Note that file-posix driver rely on permission update done during reopen
4538 * (even if no permission changed), because it wants "new" permissions for
4539 * reconfiguring the fd and that's why it does it in raw_check_perm(), not
4540 * in raw_reopen_prepare() which is called with "old" permissions.
4542 ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp);
4548 * If we reach this point, we have success and just need to apply the
4551 * Reverse order is used to comfort qcow2 driver: on commit it need to write
4552 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But
4553 * children are usually goes after parents in reopen-queue, so go from last
4556 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
4557 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4558 aio_context_acquire(ctx);
4559 bdrv_reopen_commit(&bs_entry->state);
4560 aio_context_release(ctx);
4565 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
4566 BlockDriverState *bs = bs_entry->state.bs;
4568 if (bs->drv->bdrv_reopen_commit_post) {
4569 ctx = bdrv_get_aio_context(bs);
4570 aio_context_acquire(ctx);
4571 bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
4572 aio_context_release(ctx);
4581 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
4582 if (bs_entry->prepared) {
4583 ctx = bdrv_get_aio_context(bs_entry->state.bs);
4584 aio_context_acquire(ctx);
4585 bdrv_reopen_abort(&bs_entry->state);
4586 aio_context_release(ctx);
4591 bdrv_reopen_queue_free(bs_queue);
4596 int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
4599 AioContext *ctx = bdrv_get_aio_context(bs);
4600 BlockReopenQueue *queue;
4603 GLOBAL_STATE_CODE();
4605 queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
4607 if (ctx != qemu_get_aio_context()) {
4608 aio_context_release(ctx);
4610 ret = bdrv_reopen_multiple(queue, errp);
4612 if (ctx != qemu_get_aio_context()) {
4613 aio_context_acquire(ctx);
4619 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
4622 QDict *opts = qdict_new();
4624 GLOBAL_STATE_CODE();
4626 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
4628 return bdrv_reopen(bs, opts, true, errp);
4632 * Take a BDRVReopenState and check if the value of 'backing' in the
4633 * reopen_state->options QDict is valid or not.
4635 * If 'backing' is missing from the QDict then return 0.
4637 * If 'backing' contains the node name of the backing file of
4638 * reopen_state->bs then return 0.
4640 * If 'backing' contains a different node name (or is null) then check
4641 * whether the current backing file can be replaced with the new one.
4642 * If that's the case then reopen_state->replace_backing_bs is set to
4643 * true and reopen_state->new_backing_bs contains a pointer to the new
4644 * backing BlockDriverState (or NULL).
4646 * Return 0 on success, otherwise return < 0 and set @errp.
4648 * The caller must hold the AioContext lock of @reopen_state->bs.
4649 * @reopen_state->bs can move to a different AioContext in this function.
4650 * Callers must make sure that their AioContext locking is still correct after
4653 static int bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
4654 bool is_backing, Transaction *tran,
4657 BlockDriverState *bs = reopen_state->bs;
4658 BlockDriverState *new_child_bs;
4659 BlockDriverState *old_child_bs = is_backing ? child_bs(bs->backing) :
4661 const char *child_name = is_backing ? "backing" : "file";
4664 AioContext *ctx, *old_ctx;
4667 GLOBAL_STATE_CODE();
4669 value = qdict_get(reopen_state->options, child_name);
4670 if (value == NULL) {
4674 switch (qobject_type(value)) {
4676 assert(is_backing); /* The 'file' option does not allow a null value */
4677 new_child_bs = NULL;
4680 str = qstring_get_str(qobject_to(QString, value));
4681 new_child_bs = bdrv_lookup_bs(NULL, str, errp);
4682 if (new_child_bs == NULL) {
4684 } else if (bdrv_recurse_has_child(new_child_bs, bs)) {
4685 error_setg(errp, "Making '%s' a %s child of '%s' would create a "
4686 "cycle", str, child_name, bs->node_name);
4692 * The options QDict has been flattened, so 'backing' and 'file'
4693 * do not allow any other data type here.
4695 g_assert_not_reached();
4698 if (old_child_bs == new_child_bs) {
4703 if (bdrv_skip_implicit_filters(old_child_bs) == new_child_bs) {
4707 if (old_child_bs->implicit) {
4708 error_setg(errp, "Cannot replace implicit %s child of %s",
4709 child_name, bs->node_name);
4714 if (bs->drv->is_filter && !old_child_bs) {
4716 * Filters always have a file or a backing child, so we are trying to
4717 * change wrong child
4719 error_setg(errp, "'%s' is a %s filter node that does not support a "
4720 "%s child", bs->node_name, bs->drv->format_name, child_name);
4725 reopen_state->old_backing_bs = old_child_bs;
4727 reopen_state->old_file_bs = old_child_bs;
4730 old_ctx = bdrv_get_aio_context(bs);
4731 ctx = bdrv_get_aio_context(new_child_bs);
4732 if (old_ctx != ctx) {
4733 aio_context_release(old_ctx);
4734 aio_context_acquire(ctx);
4737 ret = bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing,
4740 if (old_ctx != ctx) {
4741 aio_context_release(ctx);
4742 aio_context_acquire(old_ctx);
4749 * Prepares a BlockDriverState for reopen. All changes are staged in the
4750 * 'opaque' field of the BDRVReopenState, which is used and allocated by
4751 * the block driver layer .bdrv_reopen_prepare()
4753 * bs is the BlockDriverState to reopen
4754 * flags are the new open flags
4755 * queue is the reopen queue
4757 * Returns 0 on success, non-zero on error. On error errp will be set
4760 * On failure, bdrv_reopen_abort() will be called to clean up any data.
4761 * It is the responsibility of the caller to then call the abort() or
4762 * commit() for any other BDS that have been left in a prepare() state
4764 * The caller must hold the AioContext lock of @reopen_state->bs.
4766 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
4767 BlockReopenQueue *queue,
4768 Transaction *change_child_tran, Error **errp)
4772 Error *local_err = NULL;
4775 QDict *orig_reopen_opts;
4776 char *discard = NULL;
4778 bool drv_prepared = false;
4780 assert(reopen_state != NULL);
4781 assert(reopen_state->bs->drv != NULL);
4782 GLOBAL_STATE_CODE();
4783 drv = reopen_state->bs->drv;
4785 /* This function and each driver's bdrv_reopen_prepare() remove
4786 * entries from reopen_state->options as they are processed, so
4787 * we need to make a copy of the original QDict. */
4788 orig_reopen_opts = qdict_clone_shallow(reopen_state->options);
4790 /* Process generic block layer options */
4791 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
4792 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) {
4797 /* This was already called in bdrv_reopen_queue_child() so the flags
4798 * are up-to-date. This time we simply want to remove the options from
4799 * QemuOpts in order to indicate that they have been processed. */
4800 old_flags = reopen_state->flags;
4801 update_flags_from_options(&reopen_state->flags, opts);
4802 assert(old_flags == reopen_state->flags);
4804 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD);
4805 if (discard != NULL) {
4806 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) {
4807 error_setg(errp, "Invalid discard option");
4813 reopen_state->detect_zeroes =
4814 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err);
4816 error_propagate(errp, local_err);
4821 /* All other options (including node-name and driver) must be unchanged.
4822 * Put them back into the QDict, so that they are checked at the end
4823 * of this function. */
4824 qemu_opts_to_qdict(opts, reopen_state->options);
4826 /* If we are to stay read-only, do not allow permission change
4827 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
4828 * not set, or if the BDS still has copy_on_read enabled */
4829 read_only = !(reopen_state->flags & BDRV_O_RDWR);
4830 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
4832 error_propagate(errp, local_err);
4836 if (drv->bdrv_reopen_prepare) {
4838 * If a driver-specific option is missing, it means that we
4839 * should reset it to its default value.
4840 * But not all options allow that, so we need to check it first.
4842 ret = bdrv_reset_options_allowed(reopen_state->bs,
4843 reopen_state->options, errp);
4848 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
4850 if (local_err != NULL) {
4851 error_propagate(errp, local_err);
4853 bdrv_refresh_filename(reopen_state->bs);
4854 error_setg(errp, "failed while preparing to reopen image '%s'",
4855 reopen_state->bs->filename);
4860 /* It is currently mandatory to have a bdrv_reopen_prepare()
4861 * handler for each supported drv. */
4862 error_setg(errp, "Block format '%s' used by node '%s' "
4863 "does not support reopening files", drv->format_name,
4864 bdrv_get_device_or_node_name(reopen_state->bs));
4869 drv_prepared = true;
4872 * We must provide the 'backing' option if the BDS has a backing
4873 * file or if the image file has a backing file name as part of
4874 * its metadata. Otherwise the 'backing' option can be omitted.
4876 if (drv->supports_backing && reopen_state->backing_missing &&
4877 (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) {
4878 error_setg(errp, "backing is missing for '%s'",
4879 reopen_state->bs->node_name);
4885 * Allow changing the 'backing' option. The new value can be
4886 * either a reference to an existing node (using its node name)
4887 * or NULL to simply detach the current backing file.
4889 ret = bdrv_reopen_parse_file_or_backing(reopen_state, true,
4890 change_child_tran, errp);
4894 qdict_del(reopen_state->options, "backing");
4896 /* Allow changing the 'file' option. In this case NULL is not allowed */
4897 ret = bdrv_reopen_parse_file_or_backing(reopen_state, false,
4898 change_child_tran, errp);
4902 qdict_del(reopen_state->options, "file");
4904 /* Options that are not handled are only okay if they are unchanged
4905 * compared to the old state. It is expected that some options are only
4906 * used for the initial open, but not reopen (e.g. filename) */
4907 if (qdict_size(reopen_state->options)) {
4908 const QDictEntry *entry = qdict_first(reopen_state->options);
4911 QObject *new = entry->value;
4912 QObject *old = qdict_get(reopen_state->bs->options, entry->key);
4914 /* Allow child references (child_name=node_name) as long as they
4915 * point to the current child (i.e. everything stays the same). */
4916 if (qobject_type(new) == QTYPE_QSTRING) {
4918 QLIST_FOREACH(child, &reopen_state->bs->children, next) {
4919 if (!strcmp(child->name, entry->key)) {
4925 if (!strcmp(child->bs->node_name,
4926 qstring_get_str(qobject_to(QString, new)))) {
4927 continue; /* Found child with this name, skip option */
4933 * TODO: When using -drive to specify blockdev options, all values
4934 * will be strings; however, when using -blockdev, blockdev-add or
4935 * filenames using the json:{} pseudo-protocol, they will be
4937 * In contrast, reopening options are (currently) always strings
4938 * (because you can only specify them through qemu-io; all other
4939 * callers do not specify any options).
4940 * Therefore, when using anything other than -drive to create a BDS,
4941 * this cannot detect non-string options as unchanged, because
4942 * qobject_is_equal() always returns false for objects of different
4943 * type. In the future, this should be remedied by correctly typing
4944 * all options. For now, this is not too big of an issue because
4945 * the user can simply omit options which cannot be changed anyway,
4946 * so they will stay unchanged.
4948 if (!qobject_is_equal(new, old)) {
4949 error_setg(errp, "Cannot change the option '%s'", entry->key);
4953 } while ((entry = qdict_next(reopen_state->options, entry)));
4958 /* Restore the original reopen_state->options QDict */
4959 qobject_unref(reopen_state->options);
4960 reopen_state->options = qobject_ref(orig_reopen_opts);
4963 if (ret < 0 && drv_prepared) {
4964 /* drv->bdrv_reopen_prepare() has succeeded, so we need to
4965 * call drv->bdrv_reopen_abort() before signaling an error
4966 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort()
4967 * when the respective bdrv_reopen_prepare() has failed) */
4968 if (drv->bdrv_reopen_abort) {
4969 drv->bdrv_reopen_abort(reopen_state);
4972 qemu_opts_del(opts);
4973 qobject_unref(orig_reopen_opts);
4979 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and
4980 * makes them final by swapping the staging BlockDriverState contents into
4981 * the active BlockDriverState contents.
4983 static void bdrv_reopen_commit(BDRVReopenState *reopen_state)
4986 BlockDriverState *bs;
4989 assert(reopen_state != NULL);
4990 bs = reopen_state->bs;
4992 assert(drv != NULL);
4993 GLOBAL_STATE_CODE();
4995 /* If there are any driver level actions to take */
4996 if (drv->bdrv_reopen_commit) {
4997 drv->bdrv_reopen_commit(reopen_state);
5000 /* set BDS specific flags now */
5001 qobject_unref(bs->explicit_options);
5002 qobject_unref(bs->options);
5003 qobject_ref(reopen_state->explicit_options);
5004 qobject_ref(reopen_state->options);
5006 bs->explicit_options = reopen_state->explicit_options;
5007 bs->options = reopen_state->options;
5008 bs->open_flags = reopen_state->flags;
5009 bs->detect_zeroes = reopen_state->detect_zeroes;
5011 /* Remove child references from bs->options and bs->explicit_options.
5012 * Child options were already removed in bdrv_reopen_queue_child() */
5013 QLIST_FOREACH(child, &bs->children, next) {
5014 qdict_del(bs->explicit_options, child->name);
5015 qdict_del(bs->options, child->name);
5017 /* backing is probably removed, so it's not handled by previous loop */
5018 qdict_del(bs->explicit_options, "backing");
5019 qdict_del(bs->options, "backing");
5021 bdrv_graph_rdlock_main_loop();
5022 bdrv_refresh_limits(bs, NULL, NULL);
5023 bdrv_graph_rdunlock_main_loop();
5024 bdrv_refresh_total_sectors(bs, bs->total_sectors);
5028 * Abort the reopen, and delete and free the staged changes in
5031 static void bdrv_reopen_abort(BDRVReopenState *reopen_state)
5035 assert(reopen_state != NULL);
5036 drv = reopen_state->bs->drv;
5037 assert(drv != NULL);
5038 GLOBAL_STATE_CODE();
5040 if (drv->bdrv_reopen_abort) {
5041 drv->bdrv_reopen_abort(reopen_state);
5046 static void bdrv_close(BlockDriverState *bs)
5048 BdrvAioNotifier *ban, *ban_next;
5049 BdrvChild *child, *next;
5051 GLOBAL_STATE_CODE();
5052 assert(!bs->refcnt);
5054 bdrv_drained_begin(bs); /* complete I/O */
5056 bdrv_drain(bs); /* in case flush left pending I/O */
5059 if (bs->drv->bdrv_close) {
5060 /* Must unfreeze all children, so bdrv_unref_child() works */
5061 bs->drv->bdrv_close(bs);
5066 QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
5067 bdrv_unref_child(bs, child);
5070 assert(!bs->backing);
5074 qatomic_set(&bs->copy_on_read, 0);
5075 bs->backing_file[0] = '\0';
5076 bs->backing_format[0] = '\0';
5077 bs->total_sectors = 0;
5078 bs->encrypted = false;
5080 qobject_unref(bs->options);
5081 qobject_unref(bs->explicit_options);
5083 bs->explicit_options = NULL;
5084 qobject_unref(bs->full_open_options);
5085 bs->full_open_options = NULL;
5086 g_free(bs->block_status_cache);
5087 bs->block_status_cache = NULL;
5089 bdrv_release_named_dirty_bitmaps(bs);
5090 assert(QLIST_EMPTY(&bs->dirty_bitmaps));
5092 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
5095 QLIST_INIT(&bs->aio_notifiers);
5096 bdrv_drained_end(bs);
5099 * If we're still inside some bdrv_drain_all_begin()/end() sections, end
5100 * them now since this BDS won't exist anymore when bdrv_drain_all_end()
5103 if (bs->quiesce_counter) {
5104 bdrv_drain_all_end_quiesce(bs);
5108 void bdrv_close_all(void)
5110 GLOBAL_STATE_CODE();
5111 assert(job_next(NULL) == NULL);
5113 /* Drop references from requests still in flight, such as canceled block
5114 * jobs whose AIO context has not been polled yet */
5117 blk_remove_all_bs();
5118 blockdev_close_all_bdrv_states();
5120 assert(QTAILQ_EMPTY(&all_bdrv_states));
5123 static bool should_update_child(BdrvChild *c, BlockDriverState *to)
5129 if (c->klass->stay_at_node) {
5133 /* If the child @c belongs to the BDS @to, replacing the current
5134 * c->bs by @to would mean to create a loop.
5136 * Such a case occurs when appending a BDS to a backing chain.
5137 * For instance, imagine the following chain:
5139 * guest device -> node A -> further backing chain...
5141 * Now we create a new BDS B which we want to put on top of this
5142 * chain, so we first attach A as its backing node:
5147 * guest device -> node A -> further backing chain...
5149 * Finally we want to replace A by B. When doing that, we want to
5150 * replace all pointers to A by pointers to B -- except for the
5151 * pointer from B because (1) that would create a loop, and (2)
5152 * that pointer should simply stay intact:
5154 * guest device -> node B
5157 * node A -> further backing chain...
5159 * In general, when replacing a node A (c->bs) by a node B (@to),
5160 * if A is a child of B, that means we cannot replace A by B there
5161 * because that would create a loop. Silently detaching A from B
5162 * is also not really an option. So overall just leaving A in
5163 * place there is the most sensible choice.
5165 * We would also create a loop in any cases where @c is only
5166 * indirectly referenced by @to. Prevent this by returning false
5167 * if @c is found (by breadth-first search) anywhere in the whole
5172 found = g_hash_table_new(NULL, NULL);
5173 g_hash_table_add(found, to);
5174 queue = g_queue_new();
5175 g_queue_push_tail(queue, to);
5177 while (!g_queue_is_empty(queue)) {
5178 BlockDriverState *v = g_queue_pop_head(queue);
5181 QLIST_FOREACH(c2, &v->children, next) {
5187 if (g_hash_table_contains(found, c2->bs)) {
5191 g_queue_push_tail(queue, c2->bs);
5192 g_hash_table_add(found, c2->bs);
5196 g_queue_free(queue);
5197 g_hash_table_destroy(found);
5202 static void bdrv_remove_child_commit(void *opaque)
5204 GLOBAL_STATE_CODE();
5205 bdrv_child_free(opaque);
5208 static TransactionActionDrv bdrv_remove_child_drv = {
5209 .commit = bdrv_remove_child_commit,
5212 /* Function doesn't update permissions, caller is responsible for this. */
5213 static void bdrv_remove_child(BdrvChild *child, Transaction *tran)
5220 BlockDriverState *bs = child->bs;
5221 bdrv_drained_begin(bs);
5222 bdrv_replace_child_tran(child, NULL, tran);
5223 bdrv_drained_end(bs);
5226 tran_add(tran, &bdrv_remove_child_drv, child);
5229 static void undrain_on_clean_cb(void *opaque)
5231 bdrv_drained_end(opaque);
5234 static TransactionActionDrv undrain_on_clean = {
5235 .clean = undrain_on_clean_cb,
5238 static int bdrv_replace_node_noperm(BlockDriverState *from,
5239 BlockDriverState *to,
5240 bool auto_skip, Transaction *tran,
5243 BdrvChild *c, *next;
5245 GLOBAL_STATE_CODE();
5247 bdrv_drained_begin(from);
5248 bdrv_drained_begin(to);
5249 tran_add(tran, &undrain_on_clean, from);
5250 tran_add(tran, &undrain_on_clean, to);
5252 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
5253 assert(c->bs == from);
5254 if (!should_update_child(c, to)) {
5258 error_setg(errp, "Should not change '%s' link to '%s'",
5259 c->name, from->node_name);
5263 error_setg(errp, "Cannot change '%s' link to '%s'",
5264 c->name, from->node_name);
5267 bdrv_replace_child_tran(c, to, tran);
5274 * With auto_skip=true bdrv_replace_node_common skips updating from parents
5275 * if it creates a parent-child relation loop or if parent is block-job.
5277 * With auto_skip=false the error is returned if from has a parent which should
5280 * With @detach_subchain=true @to must be in a backing chain of @from. In this
5281 * case backing link of the cow-parent of @to is removed.
5283 static int bdrv_replace_node_common(BlockDriverState *from,
5284 BlockDriverState *to,
5285 bool auto_skip, bool detach_subchain,
5288 Transaction *tran = tran_new();
5289 g_autoptr(GSList) refresh_list = NULL;
5290 BlockDriverState *to_cow_parent = NULL;
5293 GLOBAL_STATE_CODE();
5295 if (detach_subchain) {
5296 assert(bdrv_chain_contains(from, to));
5298 for (to_cow_parent = from;
5299 bdrv_filter_or_cow_bs(to_cow_parent) != to;
5300 to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent))
5306 /* Make sure that @from doesn't go away until we have successfully attached
5307 * all of its parents to @to. */
5310 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
5311 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to));
5312 bdrv_drained_begin(from);
5315 * Do the replacement without permission update.
5316 * Replacement may influence the permissions, we should calculate new
5317 * permissions based on new graph. If we fail, we'll roll-back the
5320 ret = bdrv_replace_node_noperm(from, to, auto_skip, tran, errp);
5325 if (detach_subchain) {
5326 bdrv_remove_child(bdrv_filter_or_cow_child(to_cow_parent), tran);
5329 refresh_list = g_slist_prepend(refresh_list, to);
5330 refresh_list = g_slist_prepend(refresh_list, from);
5332 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
5340 tran_finalize(tran, ret);
5342 bdrv_drained_end(from);
5348 int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
5351 GLOBAL_STATE_CODE();
5353 return bdrv_replace_node_common(from, to, true, false, errp);
5356 int bdrv_drop_filter(BlockDriverState *bs, Error **errp)
5358 GLOBAL_STATE_CODE();
5360 return bdrv_replace_node_common(bs, bdrv_filter_or_cow_bs(bs), true, true,
5365 * Add new bs contents at the top of an image chain while the chain is
5366 * live, while keeping required fields on the top layer.
5368 * This will modify the BlockDriverState fields, and swap contents
5369 * between bs_new and bs_top. Both bs_new and bs_top are modified.
5371 * bs_new must not be attached to a BlockBackend and must not have backing
5374 * This function does not create any image files.
5376 * The caller must hold the AioContext lock for @bs_top.
5378 int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
5383 Transaction *tran = tran_new();
5384 AioContext *old_context, *new_context = NULL;
5386 GLOBAL_STATE_CODE();
5388 assert(!bs_new->backing);
5390 old_context = bdrv_get_aio_context(bs_top);
5392 child = bdrv_attach_child_noperm(bs_new, bs_top, "backing",
5393 &child_of_bds, bdrv_backing_role(bs_new),
5401 * bdrv_attach_child_noperm could change the AioContext of bs_top.
5402 * bdrv_replace_node_noperm calls bdrv_drained_begin, so let's temporarily
5403 * hold the new AioContext, since bdrv_drained_begin calls BDRV_POLL_WHILE
5404 * that assumes the new lock is taken.
5406 new_context = bdrv_get_aio_context(bs_top);
5408 if (old_context != new_context) {
5409 aio_context_release(old_context);
5410 aio_context_acquire(new_context);
5413 ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp);
5418 ret = bdrv_refresh_perms(bs_new, tran, errp);
5420 tran_finalize(tran, ret);
5422 bdrv_graph_rdlock_main_loop();
5423 bdrv_refresh_limits(bs_top, NULL, NULL);
5424 bdrv_graph_rdunlock_main_loop();
5426 if (new_context && old_context != new_context) {
5427 aio_context_release(new_context);
5428 aio_context_acquire(old_context);
5434 /* Not for empty child */
5435 int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
5439 Transaction *tran = tran_new();
5440 g_autoptr(GSList) refresh_list = NULL;
5441 BlockDriverState *old_bs = child->bs;
5443 GLOBAL_STATE_CODE();
5446 bdrv_drained_begin(old_bs);
5447 bdrv_drained_begin(new_bs);
5449 bdrv_replace_child_tran(child, new_bs, tran);
5451 refresh_list = g_slist_prepend(refresh_list, old_bs);
5452 refresh_list = g_slist_prepend(refresh_list, new_bs);
5454 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
5456 tran_finalize(tran, ret);
5458 bdrv_drained_end(old_bs);
5459 bdrv_drained_end(new_bs);
5465 static void bdrv_delete(BlockDriverState *bs)
5467 assert(bdrv_op_blocker_is_empty(bs));
5468 assert(!bs->refcnt);
5469 GLOBAL_STATE_CODE();
5471 /* remove from list, if necessary */
5472 if (bs->node_name[0] != '\0') {
5473 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
5475 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
5484 * Replace @bs by newly created block node.
5486 * @options is a QDict of options to pass to the block drivers, or NULL for an
5487 * empty set of options. The reference to the QDict belongs to the block layer
5488 * after the call (even on failure), so if the caller intends to reuse the
5489 * dictionary, it needs to use qobject_ref() before calling bdrv_open.
5491 * The caller holds the AioContext lock for @bs. It must make sure that @bs
5492 * stays in the same AioContext, i.e. @options must not refer to nodes in a
5493 * different AioContext.
5495 BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options,
5496 int flags, Error **errp)
5500 AioContext *ctx = bdrv_get_aio_context(bs);
5501 BlockDriverState *new_node_bs = NULL;
5502 const char *drvname, *node_name;
5505 drvname = qdict_get_try_str(options, "driver");
5507 error_setg(errp, "driver is not specified");
5511 drv = bdrv_find_format(drvname);
5513 error_setg(errp, "Unknown driver: '%s'", drvname);
5517 node_name = qdict_get_try_str(options, "node-name");
5519 GLOBAL_STATE_CODE();
5521 aio_context_release(ctx);
5522 aio_context_acquire(qemu_get_aio_context());
5523 new_node_bs = bdrv_new_open_driver_opts(drv, node_name, options, flags,
5525 aio_context_release(qemu_get_aio_context());
5526 aio_context_acquire(ctx);
5527 assert(bdrv_get_aio_context(bs) == ctx);
5529 options = NULL; /* bdrv_new_open_driver() eats options */
5531 error_prepend(errp, "Could not create node: ");
5535 bdrv_drained_begin(bs);
5536 ret = bdrv_replace_node(bs, new_node_bs, errp);
5537 bdrv_drained_end(bs);
5540 error_prepend(errp, "Could not replace node: ");
5547 qobject_unref(options);
5548 bdrv_unref(new_node_bs);
5553 * Run consistency checks on an image
5555 * Returns 0 if the check could be completed (it doesn't mean that the image is
5556 * free of errors) or -errno when an internal error occurred. The results of the
5557 * check are stored in res.
5559 int coroutine_fn bdrv_co_check(BlockDriverState *bs,
5560 BdrvCheckResult *res, BdrvCheckMode fix)
5563 assert_bdrv_graph_readable();
5564 if (bs->drv == NULL) {
5567 if (bs->drv->bdrv_co_check == NULL) {
5571 memset(res, 0, sizeof(*res));
5572 return bs->drv->bdrv_co_check(bs, res, fix);
5578 * -EINVAL - backing format specified, but no file
5579 * -ENOSPC - can't update the backing file because no space is left in the
5581 * -ENOTSUP - format driver doesn't support changing the backing file
5583 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file,
5584 const char *backing_fmt, bool require)
5586 BlockDriver *drv = bs->drv;
5589 GLOBAL_STATE_CODE();
5595 /* Backing file format doesn't make sense without a backing file */
5596 if (backing_fmt && !backing_file) {
5600 if (require && backing_file && !backing_fmt) {
5604 if (drv->bdrv_change_backing_file != NULL) {
5605 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
5611 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
5612 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
5613 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
5614 backing_file ?: "");
5620 * Finds the first non-filter node above bs in the chain between
5621 * active and bs. The returned node is either an immediate parent of
5622 * bs, or there are only filter nodes between the two.
5624 * Returns NULL if bs is not found in active's image chain,
5625 * or if active == bs.
5627 * Returns the bottommost base image if bs == NULL.
5629 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
5630 BlockDriverState *bs)
5633 GLOBAL_STATE_CODE();
5635 bs = bdrv_skip_filters(bs);
5636 active = bdrv_skip_filters(active);
5639 BlockDriverState *next = bdrv_backing_chain_next(active);
5649 /* Given a BDS, searches for the base layer. */
5650 BlockDriverState *bdrv_find_base(BlockDriverState *bs)
5652 GLOBAL_STATE_CODE();
5654 return bdrv_find_overlay(bs, NULL);
5658 * Return true if at least one of the COW (backing) and filter links
5659 * between @bs and @base is frozen. @errp is set if that's the case.
5660 * @base must be reachable from @bs, or NULL.
5662 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
5665 BlockDriverState *i;
5668 GLOBAL_STATE_CODE();
5670 for (i = bs; i != base; i = child_bs(child)) {
5671 child = bdrv_filter_or_cow_child(i);
5673 if (child && child->frozen) {
5674 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
5675 child->name, i->node_name, child->bs->node_name);
5684 * Freeze all COW (backing) and filter links between @bs and @base.
5685 * If any of the links is already frozen the operation is aborted and
5686 * none of the links are modified.
5687 * @base must be reachable from @bs, or NULL.
5688 * Returns 0 on success. On failure returns < 0 and sets @errp.
5690 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
5693 BlockDriverState *i;
5696 GLOBAL_STATE_CODE();
5698 if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
5702 for (i = bs; i != base; i = child_bs(child)) {
5703 child = bdrv_filter_or_cow_child(i);
5704 if (child && child->bs->never_freeze) {
5705 error_setg(errp, "Cannot freeze '%s' link to '%s'",
5706 child->name, child->bs->node_name);
5711 for (i = bs; i != base; i = child_bs(child)) {
5712 child = bdrv_filter_or_cow_child(i);
5714 child->frozen = true;
5722 * Unfreeze all COW (backing) and filter links between @bs and @base.
5723 * The caller must ensure that all links are frozen before using this
5725 * @base must be reachable from @bs, or NULL.
5727 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
5729 BlockDriverState *i;
5732 GLOBAL_STATE_CODE();
5734 for (i = bs; i != base; i = child_bs(child)) {
5735 child = bdrv_filter_or_cow_child(i);
5737 assert(child->frozen);
5738 child->frozen = false;
5744 * Drops images above 'base' up to and including 'top', and sets the image
5745 * above 'top' to have base as its backing file.
5747 * Requires that the overlay to 'top' is opened r/w, so that the backing file
5748 * information in 'bs' can be properly updated.
5750 * E.g., this will convert the following chain:
5751 * bottom <- base <- intermediate <- top <- active
5755 * bottom <- base <- active
5757 * It is allowed for bottom==base, in which case it converts:
5759 * base <- intermediate <- top <- active
5765 * If backing_file_str is non-NULL, it will be used when modifying top's
5766 * overlay image metadata.
5769 * if active == top, that is considered an error
5772 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
5773 const char *backing_file_str)
5775 BlockDriverState *explicit_top = top;
5776 bool update_inherits_from;
5778 Error *local_err = NULL;
5780 g_autoptr(GSList) updated_children = NULL;
5783 GLOBAL_STATE_CODE();
5786 bdrv_drained_begin(base);
5788 if (!top->drv || !base->drv) {
5792 /* Make sure that base is in the backing chain of top */
5793 if (!bdrv_chain_contains(top, base)) {
5797 /* If 'base' recursively inherits from 'top' then we should set
5798 * base->inherits_from to top->inherits_from after 'top' and all
5799 * other intermediate nodes have been dropped.
5800 * If 'top' is an implicit node (e.g. "commit_top") we should skip
5801 * it because no one inherits from it. We use explicit_top for that. */
5802 explicit_top = bdrv_skip_implicit_filters(explicit_top);
5803 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
5805 /* success - we can delete the intermediate states, and link top->base */
5806 if (!backing_file_str) {
5807 bdrv_refresh_filename(base);
5808 backing_file_str = base->filename;
5811 QLIST_FOREACH(c, &top->parents, next_parent) {
5812 updated_children = g_slist_prepend(updated_children, c);
5816 * It seems correct to pass detach_subchain=true here, but it triggers
5817 * one more yet not fixed bug, when due to nested aio_poll loop we switch to
5818 * another drained section, which modify the graph (for example, removing
5819 * the child, which we keep in updated_children list). So, it's a TODO.
5821 * Note, bug triggered if pass detach_subchain=true here and run
5822 * test-bdrv-drain. test_drop_intermediate_poll() test-case will crash.
5825 bdrv_replace_node_common(top, base, false, false, &local_err);
5827 error_report_err(local_err);
5831 for (p = updated_children; p; p = p->next) {
5834 if (c->klass->update_filename) {
5835 ret = c->klass->update_filename(c, base, backing_file_str,
5839 * TODO: Actually, we want to rollback all previous iterations
5840 * of this loop, and (which is almost impossible) previous
5841 * bdrv_replace_node()...
5843 * Note, that c->klass->update_filename may lead to permission
5844 * update, so it's a bad idea to call it inside permission
5845 * update transaction of bdrv_replace_node.
5847 error_report_err(local_err);
5853 if (update_inherits_from) {
5854 base->inherits_from = explicit_top->inherits_from;
5859 bdrv_drained_end(base);
5865 * Implementation of BlockDriver.bdrv_co_get_allocated_file_size() that
5866 * sums the size of all data-bearing children. (This excludes backing
5869 static int64_t coroutine_fn GRAPH_RDLOCK
5870 bdrv_sum_allocated_file_size(BlockDriverState *bs)
5873 int64_t child_size, sum = 0;
5875 QLIST_FOREACH(child, &bs->children, next) {
5876 if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
5877 BDRV_CHILD_FILTERED))
5879 child_size = bdrv_co_get_allocated_file_size(child->bs);
5880 if (child_size < 0) {
5891 * Length of a allocated file in bytes. Sparse files are counted by actual
5892 * allocated space. Return < 0 if error or unknown.
5894 int64_t coroutine_fn bdrv_co_get_allocated_file_size(BlockDriverState *bs)
5896 BlockDriver *drv = bs->drv;
5898 assert_bdrv_graph_readable();
5903 if (drv->bdrv_co_get_allocated_file_size) {
5904 return drv->bdrv_co_get_allocated_file_size(bs);
5907 if (drv->bdrv_file_open) {
5909 * Protocol drivers default to -ENOTSUP (most of their data is
5910 * not stored in any of their children (if they even have any),
5911 * so there is no generic way to figure it out).
5914 } else if (drv->is_filter) {
5915 /* Filter drivers default to the size of their filtered child */
5916 return bdrv_co_get_allocated_file_size(bdrv_filter_bs(bs));
5918 /* Other drivers default to summing their children's sizes */
5919 return bdrv_sum_allocated_file_size(bs);
5925 * @drv: Format driver
5926 * @opts: Creation options for new image
5927 * @in_bs: Existing image containing data for new image (may be NULL)
5928 * @errp: Error object
5929 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
5932 * Calculate file size required to create a new image.
5934 * If @in_bs is given then space for allocated clusters and zero clusters
5935 * from that image are included in the calculation. If @opts contains a
5936 * backing file that is shared by @in_bs then backing clusters may be omitted
5937 * from the calculation.
5939 * If @in_bs is NULL then the calculation includes no allocated clusters
5940 * unless a preallocation option is given in @opts.
5942 * Note that @in_bs may use a different BlockDriver from @drv.
5944 * If an error occurs the @errp pointer is set.
5946 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
5947 BlockDriverState *in_bs, Error **errp)
5950 if (!drv->bdrv_measure) {
5951 error_setg(errp, "Block driver '%s' does not support size measurement",
5956 return drv->bdrv_measure(opts, in_bs, errp);
5960 * Return number of sectors on success, -errno on error.
5962 int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs)
5964 BlockDriver *drv = bs->drv;
5966 assert_bdrv_graph_readable();
5971 if (bs->bl.has_variable_length) {
5972 int ret = bdrv_co_refresh_total_sectors(bs, bs->total_sectors);
5977 return bs->total_sectors;
5981 * This wrapper is written by hand because this function is in the hot I/O path,
5982 * via blk_get_geometry.
5984 int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs)
5986 BlockDriver *drv = bs->drv;
5992 if (bs->bl.has_variable_length) {
5993 int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
5999 return bs->total_sectors;
6003 * Return length in bytes on success, -errno on error.
6004 * The length is always a multiple of BDRV_SECTOR_SIZE.
6006 int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs)
6010 assert_bdrv_graph_readable();
6012 ret = bdrv_co_nb_sectors(bs);
6016 if (ret > INT64_MAX / BDRV_SECTOR_SIZE) {
6019 return ret * BDRV_SECTOR_SIZE;
6022 bool bdrv_is_sg(BlockDriverState *bs)
6029 * Return whether the given node supports compressed writes.
6031 bool bdrv_supports_compressed_writes(BlockDriverState *bs)
6033 BlockDriverState *filtered;
6036 if (!bs->drv || !block_driver_can_compress(bs->drv)) {
6040 filtered = bdrv_filter_bs(bs);
6043 * Filters can only forward compressed writes, so we have to
6046 return bdrv_supports_compressed_writes(filtered);
6052 const char *bdrv_get_format_name(BlockDriverState *bs)
6055 return bs->drv ? bs->drv->format_name : NULL;
6058 static int qsort_strcmp(const void *a, const void *b)
6060 return strcmp(*(char *const *)a, *(char *const *)b);
6063 void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
6064 void *opaque, bool read_only)
6069 const char **formats = NULL;
6071 GLOBAL_STATE_CODE();
6073 QLIST_FOREACH(drv, &bdrv_drivers, list) {
6074 if (drv->format_name) {
6078 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) {
6082 while (formats && i && !found) {
6083 found = !strcmp(formats[--i], drv->format_name);
6087 formats = g_renew(const char *, formats, count + 1);
6088 formats[count++] = drv->format_name;
6093 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) {
6094 const char *format_name = block_driver_modules[i].format_name;
6100 if (use_bdrv_whitelist &&
6101 !bdrv_format_is_whitelisted(format_name, read_only)) {
6105 while (formats && j && !found) {
6106 found = !strcmp(formats[--j], format_name);
6110 formats = g_renew(const char *, formats, count + 1);
6111 formats[count++] = format_name;
6116 qsort(formats, count, sizeof(formats[0]), qsort_strcmp);
6118 for (i = 0; i < count; i++) {
6119 it(opaque, formats[i]);
6125 /* This function is to find a node in the bs graph */
6126 BlockDriverState *bdrv_find_node(const char *node_name)
6128 BlockDriverState *bs;
6131 GLOBAL_STATE_CODE();
6133 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
6134 if (!strcmp(node_name, bs->node_name)) {
6141 /* Put this QMP function here so it can access the static graph_bdrv_states. */
6142 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
6145 BlockDeviceInfoList *list;
6146 BlockDriverState *bs;
6148 GLOBAL_STATE_CODE();
6151 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
6152 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
6154 qapi_free_BlockDeviceInfoList(list);
6157 QAPI_LIST_PREPEND(list, info);
6163 typedef struct XDbgBlockGraphConstructor {
6164 XDbgBlockGraph *graph;
6165 GHashTable *graph_nodes;
6166 } XDbgBlockGraphConstructor;
6168 static XDbgBlockGraphConstructor *xdbg_graph_new(void)
6170 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1);
6172 gr->graph = g_new0(XDbgBlockGraph, 1);
6173 gr->graph_nodes = g_hash_table_new(NULL, NULL);
6178 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr)
6180 XDbgBlockGraph *graph = gr->graph;
6182 g_hash_table_destroy(gr->graph_nodes);
6188 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node)
6190 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node);
6197 * Start counting from 1, not 0, because 0 interferes with not-found (NULL)
6198 * answer of g_hash_table_lookup.
6200 ret = g_hash_table_size(gr->graph_nodes) + 1;
6201 g_hash_table_insert(gr->graph_nodes, node, (void *)ret);
6206 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node,
6207 XDbgBlockGraphNodeType type, const char *name)
6209 XDbgBlockGraphNode *n;
6211 n = g_new0(XDbgBlockGraphNode, 1);
6213 n->id = xdbg_graph_node_num(gr, node);
6215 n->name = g_strdup(name);
6217 QAPI_LIST_PREPEND(gr->graph->nodes, n);
6220 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent,
6221 const BdrvChild *child)
6223 BlockPermission qapi_perm;
6224 XDbgBlockGraphEdge *edge;
6225 GLOBAL_STATE_CODE();
6227 edge = g_new0(XDbgBlockGraphEdge, 1);
6229 edge->parent = xdbg_graph_node_num(gr, parent);
6230 edge->child = xdbg_graph_node_num(gr, child->bs);
6231 edge->name = g_strdup(child->name);
6233 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) {
6234 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm);
6236 if (flag & child->perm) {
6237 QAPI_LIST_PREPEND(edge->perm, qapi_perm);
6239 if (flag & child->shared_perm) {
6240 QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm);
6244 QAPI_LIST_PREPEND(gr->graph->edges, edge);
6248 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp)
6252 BlockDriverState *bs;
6254 XDbgBlockGraphConstructor *gr = xdbg_graph_new();
6256 GLOBAL_STATE_CODE();
6258 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
6259 char *allocated_name = NULL;
6260 const char *name = blk_name(blk);
6263 name = allocated_name = blk_get_attached_dev_id(blk);
6265 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND,
6267 g_free(allocated_name);
6268 if (blk_root(blk)) {
6269 xdbg_graph_add_edge(gr, blk, blk_root(blk));
6273 WITH_JOB_LOCK_GUARD() {
6274 for (job = block_job_next_locked(NULL); job;
6275 job = block_job_next_locked(job)) {
6278 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB,
6280 for (el = job->nodes; el; el = el->next) {
6281 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data);
6286 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
6287 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER,
6289 QLIST_FOREACH(child, &bs->children, next) {
6290 xdbg_graph_add_edge(gr, bs, child);
6294 return xdbg_graph_finalize(gr);
6297 BlockDriverState *bdrv_lookup_bs(const char *device,
6298 const char *node_name,
6302 BlockDriverState *bs;
6304 GLOBAL_STATE_CODE();
6307 blk = blk_by_name(device);
6312 error_setg(errp, "Device '%s' has no medium", device);
6320 bs = bdrv_find_node(node_name);
6327 error_setg(errp, "Cannot find device=\'%s\' nor node-name=\'%s\'",
6328 device ? device : "",
6329 node_name ? node_name : "");
6333 /* If 'base' is in the same chain as 'top', return true. Otherwise,
6334 * return false. If either argument is NULL, return false. */
6335 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
6338 GLOBAL_STATE_CODE();
6340 while (top && top != base) {
6341 top = bdrv_filter_or_cow_bs(top);
6347 BlockDriverState *bdrv_next_node(BlockDriverState *bs)
6349 GLOBAL_STATE_CODE();
6351 return QTAILQ_FIRST(&graph_bdrv_states);
6353 return QTAILQ_NEXT(bs, node_list);
6356 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs)
6358 GLOBAL_STATE_CODE();
6360 return QTAILQ_FIRST(&all_bdrv_states);
6362 return QTAILQ_NEXT(bs, bs_list);
6365 const char *bdrv_get_node_name(const BlockDriverState *bs)
6368 return bs->node_name;
6371 const char *bdrv_get_parent_name(const BlockDriverState *bs)
6377 /* If multiple parents have a name, just pick the first one. */
6378 QLIST_FOREACH(c, &bs->parents, next_parent) {
6379 if (c->klass->get_name) {
6380 name = c->klass->get_name(c);
6381 if (name && *name) {
6390 /* TODO check what callers really want: bs->node_name or blk_name() */
6391 const char *bdrv_get_device_name(const BlockDriverState *bs)
6394 return bdrv_get_parent_name(bs) ?: "";
6397 /* This can be used to identify nodes that might not have a device
6398 * name associated. Since node and device names live in the same
6399 * namespace, the result is unambiguous. The exception is if both are
6400 * absent, then this returns an empty (non-null) string. */
6401 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
6404 return bdrv_get_parent_name(bs) ?: bs->node_name;
6407 int bdrv_get_flags(BlockDriverState *bs)
6410 return bs->open_flags;
6413 int bdrv_has_zero_init_1(BlockDriverState *bs)
6415 GLOBAL_STATE_CODE();
6419 int bdrv_has_zero_init(BlockDriverState *bs)
6421 BlockDriverState *filtered;
6422 GLOBAL_STATE_CODE();
6428 /* If BS is a copy on write image, it is initialized to
6429 the contents of the base image, which may not be zeroes. */
6430 if (bdrv_cow_child(bs)) {
6433 if (bs->drv->bdrv_has_zero_init) {
6434 return bs->drv->bdrv_has_zero_init(bs);
6437 filtered = bdrv_filter_bs(bs);
6439 return bdrv_has_zero_init(filtered);
6446 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
6449 if (!(bs->open_flags & BDRV_O_UNMAP)) {
6453 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
6456 void bdrv_get_backing_filename(BlockDriverState *bs,
6457 char *filename, int filename_size)
6460 pstrcpy(filename, filename_size, bs->backing_file);
6463 int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
6466 BlockDriver *drv = bs->drv;
6468 assert_bdrv_graph_readable();
6470 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
6474 if (!drv->bdrv_co_get_info) {
6475 BlockDriverState *filtered = bdrv_filter_bs(bs);
6477 return bdrv_co_get_info(filtered, bdi);
6481 memset(bdi, 0, sizeof(*bdi));
6482 ret = drv->bdrv_co_get_info(bs, bdi);
6487 if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) {
6494 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
6497 BlockDriver *drv = bs->drv;
6499 if (drv && drv->bdrv_get_specific_info) {
6500 return drv->bdrv_get_specific_info(bs, errp);
6505 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs)
6507 BlockDriver *drv = bs->drv;
6509 if (!drv || !drv->bdrv_get_specific_stats) {
6512 return drv->bdrv_get_specific_stats(bs);
6515 void coroutine_fn bdrv_co_debug_event(BlockDriverState *bs, BlkdebugEvent event)
6518 assert_bdrv_graph_readable();
6520 if (!bs || !bs->drv || !bs->drv->bdrv_co_debug_event) {
6524 bs->drv->bdrv_co_debug_event(bs, event);
6527 static BlockDriverState *bdrv_find_debug_node(BlockDriverState *bs)
6529 GLOBAL_STATE_CODE();
6530 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
6531 bs = bdrv_primary_bs(bs);
6534 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
6535 assert(bs->drv->bdrv_debug_remove_breakpoint);
6542 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event,
6545 GLOBAL_STATE_CODE();
6546 bs = bdrv_find_debug_node(bs);
6548 return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
6554 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
6556 GLOBAL_STATE_CODE();
6557 bs = bdrv_find_debug_node(bs);
6559 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
6565 int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
6567 GLOBAL_STATE_CODE();
6568 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
6569 bs = bdrv_primary_bs(bs);
6572 if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
6573 return bs->drv->bdrv_debug_resume(bs, tag);
6579 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
6581 GLOBAL_STATE_CODE();
6582 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
6583 bs = bdrv_primary_bs(bs);
6586 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
6587 return bs->drv->bdrv_debug_is_suspended(bs, tag);
6593 /* backing_file can either be relative, or absolute, or a protocol. If it is
6594 * relative, it must be relative to the chain. So, passing in bs->filename
6595 * from a BDS as backing_file should not be done, as that may be relative to
6596 * the CWD rather than the chain. */
6597 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
6598 const char *backing_file)
6600 char *filename_full = NULL;
6601 char *backing_file_full = NULL;
6602 char *filename_tmp = NULL;
6603 int is_protocol = 0;
6604 bool filenames_refreshed = false;
6605 BlockDriverState *curr_bs = NULL;
6606 BlockDriverState *retval = NULL;
6607 BlockDriverState *bs_below;
6609 GLOBAL_STATE_CODE();
6611 if (!bs || !bs->drv || !backing_file) {
6615 filename_full = g_malloc(PATH_MAX);
6616 backing_file_full = g_malloc(PATH_MAX);
6618 is_protocol = path_has_protocol(backing_file);
6621 * Being largely a legacy function, skip any filters here
6622 * (because filters do not have normal filenames, so they cannot
6623 * match anyway; and allowing json:{} filenames is a bit out of
6626 for (curr_bs = bdrv_skip_filters(bs);
6627 bdrv_cow_child(curr_bs) != NULL;
6630 bs_below = bdrv_backing_chain_next(curr_bs);
6632 if (bdrv_backing_overridden(curr_bs)) {
6634 * If the backing file was overridden, we can only compare
6635 * directly against the backing node's filename.
6638 if (!filenames_refreshed) {
6640 * This will automatically refresh all of the
6641 * filenames in the rest of the backing chain, so we
6642 * only need to do this once.
6644 bdrv_refresh_filename(bs_below);
6645 filenames_refreshed = true;
6648 if (strcmp(backing_file, bs_below->filename) == 0) {
6652 } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
6654 * If either of the filename paths is actually a protocol, then
6655 * compare unmodified paths; otherwise make paths relative.
6657 char *backing_file_full_ret;
6659 if (strcmp(backing_file, curr_bs->backing_file) == 0) {
6663 /* Also check against the full backing filename for the image */
6664 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs,
6666 if (backing_file_full_ret) {
6667 bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
6668 g_free(backing_file_full_ret);
6675 /* If not an absolute filename path, make it relative to the current
6676 * image's filename path */
6677 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
6679 /* We are going to compare canonicalized absolute pathnames */
6680 if (!filename_tmp || !realpath(filename_tmp, filename_full)) {
6681 g_free(filename_tmp);
6684 g_free(filename_tmp);
6686 /* We need to make sure the backing filename we are comparing against
6687 * is relative to the current image filename (or absolute) */
6688 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
6689 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) {
6690 g_free(filename_tmp);
6693 g_free(filename_tmp);
6695 if (strcmp(backing_file_full, filename_full) == 0) {
6702 g_free(filename_full);
6703 g_free(backing_file_full);
6707 void bdrv_init(void)
6709 #ifdef CONFIG_BDRV_WHITELIST_TOOLS
6710 use_bdrv_whitelist = 1;
6712 module_call_init(MODULE_INIT_BLOCK);
6715 void bdrv_init_with_whitelist(void)
6717 use_bdrv_whitelist = 1;
6721 int bdrv_activate(BlockDriverState *bs, Error **errp)
6723 BdrvChild *child, *parent;
6724 Error *local_err = NULL;
6726 BdrvDirtyBitmap *bm;
6728 GLOBAL_STATE_CODE();
6734 QLIST_FOREACH(child, &bs->children, next) {
6735 bdrv_activate(child->bs, &local_err);
6737 error_propagate(errp, local_err);
6743 * Update permissions, they may differ for inactive nodes.
6745 * Note that the required permissions of inactive images are always a
6746 * subset of the permissions required after activating the image. This
6747 * allows us to just get the permissions upfront without restricting
6748 * bdrv_co_invalidate_cache().
6750 * It also means that in error cases, we don't have to try and revert to
6751 * the old permissions (which is an operation that could fail, too). We can
6752 * just keep the extended permissions for the next time that an activation
6753 * of the image is tried.
6755 if (bs->open_flags & BDRV_O_INACTIVE) {
6756 bs->open_flags &= ~BDRV_O_INACTIVE;
6757 ret = bdrv_refresh_perms(bs, NULL, errp);
6759 bs->open_flags |= BDRV_O_INACTIVE;
6763 ret = bdrv_invalidate_cache(bs, errp);
6765 bs->open_flags |= BDRV_O_INACTIVE;
6769 FOR_EACH_DIRTY_BITMAP(bs, bm) {
6770 bdrv_dirty_bitmap_skip_store(bm, false);
6773 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
6775 bs->open_flags |= BDRV_O_INACTIVE;
6776 error_setg_errno(errp, -ret, "Could not refresh total sector count");
6781 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6782 if (parent->klass->activate) {
6783 parent->klass->activate(parent, &local_err);
6785 bs->open_flags |= BDRV_O_INACTIVE;
6786 error_propagate(errp, local_err);
6795 int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp)
6797 Error *local_err = NULL;
6800 assert(!(bs->open_flags & BDRV_O_INACTIVE));
6801 assert_bdrv_graph_readable();
6803 if (bs->drv->bdrv_co_invalidate_cache) {
6804 bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
6806 error_propagate(errp, local_err);
6814 void bdrv_activate_all(Error **errp)
6816 BlockDriverState *bs;
6817 BdrvNextIterator it;
6819 GLOBAL_STATE_CODE();
6821 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
6822 AioContext *aio_context = bdrv_get_aio_context(bs);
6825 aio_context_acquire(aio_context);
6826 ret = bdrv_activate(bs, errp);
6827 aio_context_release(aio_context);
6829 bdrv_next_cleanup(&it);
6835 static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
6838 GLOBAL_STATE_CODE();
6840 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6841 if (parent->klass->parent_is_bds) {
6842 BlockDriverState *parent_bs = parent->opaque;
6843 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) {
6852 static int bdrv_inactivate_recurse(BlockDriverState *bs)
6854 BdrvChild *child, *parent;
6856 uint64_t cumulative_perms, cumulative_shared_perms;
6858 GLOBAL_STATE_CODE();
6864 /* Make sure that we don't inactivate a child before its parent.
6865 * It will be covered by recursion from the yet active parent. */
6866 if (bdrv_has_bds_parent(bs, true)) {
6870 assert(!(bs->open_flags & BDRV_O_INACTIVE));
6872 /* Inactivate this node */
6873 if (bs->drv->bdrv_inactivate) {
6874 ret = bs->drv->bdrv_inactivate(bs);
6880 QLIST_FOREACH(parent, &bs->parents, next_parent) {
6881 if (parent->klass->inactivate) {
6882 ret = parent->klass->inactivate(parent);
6889 bdrv_get_cumulative_perm(bs, &cumulative_perms,
6890 &cumulative_shared_perms);
6891 if (cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
6892 /* Our inactive parents still need write access. Inactivation failed. */
6896 bs->open_flags |= BDRV_O_INACTIVE;
6899 * Update permissions, they may differ for inactive nodes.
6900 * We only tried to loosen restrictions, so errors are not fatal, ignore
6903 bdrv_refresh_perms(bs, NULL, NULL);
6905 /* Recursively inactivate children */
6906 QLIST_FOREACH(child, &bs->children, next) {
6907 ret = bdrv_inactivate_recurse(child->bs);
6916 int bdrv_inactivate_all(void)
6918 BlockDriverState *bs = NULL;
6919 BdrvNextIterator it;
6921 GSList *aio_ctxs = NULL, *ctx;
6923 GLOBAL_STATE_CODE();
6925 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
6926 AioContext *aio_context = bdrv_get_aio_context(bs);
6928 if (!g_slist_find(aio_ctxs, aio_context)) {
6929 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
6930 aio_context_acquire(aio_context);
6934 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
6935 /* Nodes with BDS parents are covered by recursion from the last
6936 * parent that gets inactivated. Don't inactivate them a second
6937 * time if that has already happened. */
6938 if (bdrv_has_bds_parent(bs, false)) {
6941 ret = bdrv_inactivate_recurse(bs);
6943 bdrv_next_cleanup(&it);
6949 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
6950 AioContext *aio_context = ctx->data;
6951 aio_context_release(aio_context);
6953 g_slist_free(aio_ctxs);
6958 /**************************************************************/
6959 /* removable device support */
6962 * Return TRUE if the media is present
6964 bool coroutine_fn bdrv_co_is_inserted(BlockDriverState *bs)
6966 BlockDriver *drv = bs->drv;
6969 assert_bdrv_graph_readable();
6974 if (drv->bdrv_co_is_inserted) {
6975 return drv->bdrv_co_is_inserted(bs);
6977 QLIST_FOREACH(child, &bs->children, next) {
6978 if (!bdrv_co_is_inserted(child->bs)) {
6986 * If eject_flag is TRUE, eject the media. Otherwise, close the tray
6988 void coroutine_fn bdrv_co_eject(BlockDriverState *bs, bool eject_flag)
6990 BlockDriver *drv = bs->drv;
6992 assert_bdrv_graph_readable();
6994 if (drv && drv->bdrv_co_eject) {
6995 drv->bdrv_co_eject(bs, eject_flag);
7000 * Lock or unlock the media (if it is locked, the user won't be able
7001 * to eject it manually).
7003 void coroutine_fn bdrv_co_lock_medium(BlockDriverState *bs, bool locked)
7005 BlockDriver *drv = bs->drv;
7007 assert_bdrv_graph_readable();
7008 trace_bdrv_lock_medium(bs, locked);
7010 if (drv && drv->bdrv_co_lock_medium) {
7011 drv->bdrv_co_lock_medium(bs, locked);
7015 /* Get a reference to bs */
7016 void bdrv_ref(BlockDriverState *bs)
7018 GLOBAL_STATE_CODE();
7022 /* Release a previously grabbed reference to bs.
7023 * If after releasing, reference count is zero, the BlockDriverState is
7025 void bdrv_unref(BlockDriverState *bs)
7027 GLOBAL_STATE_CODE();
7031 assert(bs->refcnt > 0);
7032 if (--bs->refcnt == 0) {
7037 struct BdrvOpBlocker {
7039 QLIST_ENTRY(BdrvOpBlocker) list;
7042 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
7044 BdrvOpBlocker *blocker;
7045 GLOBAL_STATE_CODE();
7046 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
7047 if (!QLIST_EMPTY(&bs->op_blockers[op])) {
7048 blocker = QLIST_FIRST(&bs->op_blockers[op]);
7049 error_propagate_prepend(errp, error_copy(blocker->reason),
7050 "Node '%s' is busy: ",
7051 bdrv_get_device_or_node_name(bs));
7057 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
7059 BdrvOpBlocker *blocker;
7060 GLOBAL_STATE_CODE();
7061 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
7063 blocker = g_new0(BdrvOpBlocker, 1);
7064 blocker->reason = reason;
7065 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
7068 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
7070 BdrvOpBlocker *blocker, *next;
7071 GLOBAL_STATE_CODE();
7072 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
7073 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
7074 if (blocker->reason == reason) {
7075 QLIST_REMOVE(blocker, list);
7081 void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
7084 GLOBAL_STATE_CODE();
7085 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
7086 bdrv_op_block(bs, i, reason);
7090 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
7093 GLOBAL_STATE_CODE();
7094 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
7095 bdrv_op_unblock(bs, i, reason);
7099 bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
7102 GLOBAL_STATE_CODE();
7103 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
7104 if (!QLIST_EMPTY(&bs->op_blockers[i])) {
7112 * Must not be called while holding the lock of an AioContext other than the
7115 void bdrv_img_create(const char *filename, const char *fmt,
7116 const char *base_filename, const char *base_fmt,
7117 char *options, uint64_t img_size, int flags, bool quiet,
7120 QemuOptsList *create_opts = NULL;
7121 QemuOpts *opts = NULL;
7122 const char *backing_fmt, *backing_file;
7124 BlockDriver *drv, *proto_drv;
7125 Error *local_err = NULL;
7128 GLOBAL_STATE_CODE();
7130 /* Find driver and parse its options */
7131 drv = bdrv_find_format(fmt);
7133 error_setg(errp, "Unknown file format '%s'", fmt);
7137 proto_drv = bdrv_find_protocol(filename, true, errp);
7142 if (!drv->create_opts) {
7143 error_setg(errp, "Format driver '%s' does not support image creation",
7148 if (!proto_drv->create_opts) {
7149 error_setg(errp, "Protocol driver '%s' does not support image creation",
7150 proto_drv->format_name);
7154 aio_context_acquire(qemu_get_aio_context());
7156 /* Create parameter list */
7157 create_opts = qemu_opts_append(create_opts, drv->create_opts);
7158 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
7160 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
7162 /* Parse -o options */
7164 if (!qemu_opts_do_parse(opts, options, NULL, errp)) {
7169 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) {
7170 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort);
7171 } else if (img_size != UINT64_C(-1)) {
7172 error_setg(errp, "The image size must be specified only once");
7176 if (base_filename) {
7177 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename,
7179 error_setg(errp, "Backing file not supported for file format '%s'",
7186 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) {
7187 error_setg(errp, "Backing file format not supported for file "
7188 "format '%s'", fmt);
7193 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
7195 if (!strcmp(filename, backing_file)) {
7196 error_setg(errp, "Error: Trying to create an image with the "
7197 "same filename as the backing file");
7200 if (backing_file[0] == '\0') {
7201 error_setg(errp, "Expected backing file name, got empty string");
7206 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
7208 /* The size for the image must always be specified, unless we have a backing
7209 * file and we have not been forbidden from opening it. */
7210 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
7211 if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
7212 BlockDriverState *bs;
7215 QDict *backing_options = NULL;
7218 bdrv_get_full_backing_filename_from_filename(filename, backing_file,
7223 assert(full_backing);
7226 * No need to do I/O here, which allows us to open encrypted
7227 * backing images without needing the secret
7230 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
7231 back_flags |= BDRV_O_NO_IO;
7233 backing_options = qdict_new();
7235 qdict_put_str(backing_options, "driver", backing_fmt);
7237 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
7239 bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
7241 g_free(full_backing);
7243 error_append_hint(&local_err, "Could not open backing image.\n");
7247 error_setg(&local_err,
7248 "Backing file specified without backing format");
7249 error_append_hint(&local_err, "Detected format of %s.\n",
7250 bs->drv->format_name);
7254 /* Opened BS, have no size */
7255 size = bdrv_getlength(bs);
7257 error_setg_errno(errp, -size, "Could not get size of '%s'",
7262 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
7266 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
7267 } else if (backing_file && !backing_fmt) {
7268 error_setg(&local_err,
7269 "Backing file specified without backing format");
7274 error_setg(errp, "Image creation needs a size parameter");
7279 printf("Formatting '%s', fmt=%s ", filename, fmt);
7280 qemu_opts_print(opts, " ");
7285 ret = bdrv_create(drv, filename, opts, &local_err);
7287 if (ret == -EFBIG) {
7288 /* This is generally a better message than whatever the driver would
7289 * deliver (especially because of the cluster_size_hint), since that
7290 * is most probably not much different from "image too large". */
7291 const char *cluster_size_hint = "";
7292 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) {
7293 cluster_size_hint = " (try using a larger cluster size)";
7295 error_setg(errp, "The image size is too large for file format '%s'"
7296 "%s", fmt, cluster_size_hint);
7297 error_free(local_err);
7302 qemu_opts_del(opts);
7303 qemu_opts_free(create_opts);
7304 error_propagate(errp, local_err);
7305 aio_context_release(qemu_get_aio_context());
7308 AioContext *bdrv_get_aio_context(BlockDriverState *bs)
7311 return bs ? bs->aio_context : qemu_get_aio_context();
7314 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs)
7316 Coroutine *self = qemu_coroutine_self();
7317 AioContext *old_ctx = qemu_coroutine_get_aio_context(self);
7318 AioContext *new_ctx;
7322 * Increase bs->in_flight to ensure that this operation is completed before
7323 * moving the node to a different AioContext. Read new_ctx only afterwards.
7325 bdrv_inc_in_flight(bs);
7327 new_ctx = bdrv_get_aio_context(bs);
7328 aio_co_reschedule_self(new_ctx);
7332 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx)
7335 aio_co_reschedule_self(old_ctx);
7336 bdrv_dec_in_flight(bs);
7339 void coroutine_fn bdrv_co_lock(BlockDriverState *bs)
7341 AioContext *ctx = bdrv_get_aio_context(bs);
7343 /* In the main thread, bs->aio_context won't change concurrently */
7344 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
7347 * We're in coroutine context, so we already hold the lock of the main
7348 * loop AioContext. Don't lock it twice to avoid deadlocks.
7350 assert(qemu_in_coroutine());
7351 if (ctx != qemu_get_aio_context()) {
7352 aio_context_acquire(ctx);
7356 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs)
7358 AioContext *ctx = bdrv_get_aio_context(bs);
7360 assert(qemu_in_coroutine());
7361 if (ctx != qemu_get_aio_context()) {
7362 aio_context_release(ctx);
7366 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
7368 GLOBAL_STATE_CODE();
7369 QLIST_REMOVE(ban, list);
7373 static void bdrv_detach_aio_context(BlockDriverState *bs)
7375 BdrvAioNotifier *baf, *baf_tmp;
7377 assert(!bs->walking_aio_notifiers);
7378 GLOBAL_STATE_CODE();
7379 bs->walking_aio_notifiers = true;
7380 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
7382 bdrv_do_remove_aio_context_notifier(baf);
7384 baf->detach_aio_context(baf->opaque);
7387 /* Never mind iterating again to check for ->deleted. bdrv_close() will
7388 * remove remaining aio notifiers if we aren't called again.
7390 bs->walking_aio_notifiers = false;
7392 if (bs->drv && bs->drv->bdrv_detach_aio_context) {
7393 bs->drv->bdrv_detach_aio_context(bs);
7396 bs->aio_context = NULL;
7399 static void bdrv_attach_aio_context(BlockDriverState *bs,
7400 AioContext *new_context)
7402 BdrvAioNotifier *ban, *ban_tmp;
7403 GLOBAL_STATE_CODE();
7405 bs->aio_context = new_context;
7407 if (bs->drv && bs->drv->bdrv_attach_aio_context) {
7408 bs->drv->bdrv_attach_aio_context(bs, new_context);
7411 assert(!bs->walking_aio_notifiers);
7412 bs->walking_aio_notifiers = true;
7413 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) {
7415 bdrv_do_remove_aio_context_notifier(ban);
7417 ban->attached_aio_context(new_context, ban->opaque);
7420 bs->walking_aio_notifiers = false;
7423 typedef struct BdrvStateSetAioContext {
7424 AioContext *new_ctx;
7425 BlockDriverState *bs;
7426 } BdrvStateSetAioContext;
7428 static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx,
7429 GHashTable *visited,
7433 GLOBAL_STATE_CODE();
7434 if (g_hash_table_contains(visited, c)) {
7437 g_hash_table_add(visited, c);
7440 * A BdrvChildClass that doesn't handle AioContext changes cannot
7441 * tolerate any AioContext changes
7443 if (!c->klass->change_aio_ctx) {
7444 char *user = bdrv_child_user_desc(c);
7445 error_setg(errp, "Changing iothreads is not supported by %s", user);
7449 if (!c->klass->change_aio_ctx(c, ctx, visited, tran, errp)) {
7450 assert(!errp || *errp);
7456 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
7457 GHashTable *visited, Transaction *tran,
7460 GLOBAL_STATE_CODE();
7461 if (g_hash_table_contains(visited, c)) {
7464 g_hash_table_add(visited, c);
7465 return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp);
7468 static void bdrv_set_aio_context_clean(void *opaque)
7470 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
7471 BlockDriverState *bs = (BlockDriverState *) state->bs;
7473 /* Paired with bdrv_drained_begin in bdrv_change_aio_context() */
7474 bdrv_drained_end(bs);
7479 static void bdrv_set_aio_context_commit(void *opaque)
7481 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
7482 BlockDriverState *bs = (BlockDriverState *) state->bs;
7483 AioContext *new_context = state->new_ctx;
7484 AioContext *old_context = bdrv_get_aio_context(bs);
7487 * Take the old AioContex when detaching it from bs.
7488 * At this point, new_context lock is already acquired, and we are now
7489 * also taking old_context. This is safe as long as bdrv_detach_aio_context
7490 * does not call AIO_POLL_WHILE().
7492 if (old_context != qemu_get_aio_context()) {
7493 aio_context_acquire(old_context);
7495 bdrv_detach_aio_context(bs);
7496 if (old_context != qemu_get_aio_context()) {
7497 aio_context_release(old_context);
7499 bdrv_attach_aio_context(bs, new_context);
7502 static TransactionActionDrv set_aio_context = {
7503 .commit = bdrv_set_aio_context_commit,
7504 .clean = bdrv_set_aio_context_clean,
7508 * Changes the AioContext used for fd handlers, timers, and BHs by this
7509 * BlockDriverState and all its children and parents.
7511 * Must be called from the main AioContext.
7513 * The caller must own the AioContext lock for the old AioContext of bs, but it
7514 * must not own the AioContext lock for new_context (unless new_context is the
7515 * same as the current context of bs).
7517 * @visited will accumulate all visited BdrvChild objects. The caller is
7518 * responsible for freeing the list afterwards.
7520 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
7521 GHashTable *visited, Transaction *tran,
7525 BdrvStateSetAioContext *state;
7527 GLOBAL_STATE_CODE();
7529 if (bdrv_get_aio_context(bs) == ctx) {
7533 QLIST_FOREACH(c, &bs->parents, next_parent) {
7534 if (!bdrv_parent_change_aio_context(c, ctx, visited, tran, errp)) {
7539 QLIST_FOREACH(c, &bs->children, next) {
7540 if (!bdrv_child_change_aio_context(c, ctx, visited, tran, errp)) {
7545 state = g_new(BdrvStateSetAioContext, 1);
7546 *state = (BdrvStateSetAioContext) {
7551 /* Paired with bdrv_drained_end in bdrv_set_aio_context_clean() */
7552 bdrv_drained_begin(bs);
7554 tran_add(tran, &set_aio_context, state);
7560 * Change bs's and recursively all of its parents' and children's AioContext
7561 * to the given new context, returning an error if that isn't possible.
7563 * If ignore_child is not NULL, that child (and its subgraph) will not
7566 * This function still requires the caller to take the bs current
7567 * AioContext lock, otherwise draining will fail since AIO_WAIT_WHILE
7568 * assumes the lock is always held if bs is in another AioContext.
7569 * For the same reason, it temporarily also holds the new AioContext, since
7570 * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too.
7571 * Therefore the new AioContext lock must not be taken by the caller.
7573 int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
7574 BdrvChild *ignore_child, Error **errp)
7577 GHashTable *visited;
7579 AioContext *old_context = bdrv_get_aio_context(bs);
7580 GLOBAL_STATE_CODE();
7583 * Recursion phase: go through all nodes of the graph.
7584 * Take care of checking that all nodes support changing AioContext
7585 * and drain them, builing a linear list of callbacks to run if everything
7586 * is successful (the transaction itself).
7589 visited = g_hash_table_new(NULL, NULL);
7591 g_hash_table_add(visited, ignore_child);
7593 ret = bdrv_change_aio_context(bs, ctx, visited, tran, errp);
7594 g_hash_table_destroy(visited);
7597 * Linear phase: go through all callbacks collected in the transaction.
7598 * Run all callbacks collected in the recursion to switch all nodes
7599 * AioContext lock (transaction commit), or undo all changes done in the
7600 * recursion (transaction abort).
7604 /* Just run clean() callbacks. No AioContext changed. */
7610 * Release old AioContext, it won't be needed anymore, as all
7611 * bdrv_drained_begin() have been called already.
7613 if (qemu_get_aio_context() != old_context) {
7614 aio_context_release(old_context);
7618 * Acquire new AioContext since bdrv_drained_end() is going to be called
7619 * after we switched all nodes in the new AioContext, and the function
7620 * assumes that the lock of the bs is always taken.
7622 if (qemu_get_aio_context() != ctx) {
7623 aio_context_acquire(ctx);
7628 if (qemu_get_aio_context() != ctx) {
7629 aio_context_release(ctx);
7632 /* Re-acquire the old AioContext, since the caller takes and releases it. */
7633 if (qemu_get_aio_context() != old_context) {
7634 aio_context_acquire(old_context);
7640 void bdrv_add_aio_context_notifier(BlockDriverState *bs,
7641 void (*attached_aio_context)(AioContext *new_context, void *opaque),
7642 void (*detach_aio_context)(void *opaque), void *opaque)
7644 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1);
7645 *ban = (BdrvAioNotifier){
7646 .attached_aio_context = attached_aio_context,
7647 .detach_aio_context = detach_aio_context,
7650 GLOBAL_STATE_CODE();
7652 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list);
7655 void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
7656 void (*attached_aio_context)(AioContext *,
7658 void (*detach_aio_context)(void *),
7661 BdrvAioNotifier *ban, *ban_next;
7662 GLOBAL_STATE_CODE();
7664 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
7665 if (ban->attached_aio_context == attached_aio_context &&
7666 ban->detach_aio_context == detach_aio_context &&
7667 ban->opaque == opaque &&
7668 ban->deleted == false)
7670 if (bs->walking_aio_notifiers) {
7671 ban->deleted = true;
7673 bdrv_do_remove_aio_context_notifier(ban);
7682 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
7683 BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
7687 GLOBAL_STATE_CODE();
7689 error_setg(errp, "Node is ejected");
7692 if (!bs->drv->bdrv_amend_options) {
7693 error_setg(errp, "Block driver '%s' does not support option amendment",
7694 bs->drv->format_name);
7697 return bs->drv->bdrv_amend_options(bs, opts, status_cb,
7698 cb_opaque, force, errp);
7702 * This function checks whether the given @to_replace is allowed to be
7703 * replaced by a node that always shows the same data as @bs. This is
7704 * used for example to verify whether the mirror job can replace
7705 * @to_replace by the target mirrored from @bs.
7706 * To be replaceable, @bs and @to_replace may either be guaranteed to
7707 * always show the same data (because they are only connected through
7708 * filters), or some driver may allow replacing one of its children
7709 * because it can guarantee that this child's data is not visible at
7710 * all (for example, for dissenting quorum children that have no other
7713 bool bdrv_recurse_can_replace(BlockDriverState *bs,
7714 BlockDriverState *to_replace)
7716 BlockDriverState *filtered;
7718 GLOBAL_STATE_CODE();
7720 if (!bs || !bs->drv) {
7724 if (bs == to_replace) {
7728 /* See what the driver can do */
7729 if (bs->drv->bdrv_recurse_can_replace) {
7730 return bs->drv->bdrv_recurse_can_replace(bs, to_replace);
7733 /* For filters without an own implementation, we can recurse on our own */
7734 filtered = bdrv_filter_bs(bs);
7736 return bdrv_recurse_can_replace(filtered, to_replace);
7744 * Check whether the given @node_name can be replaced by a node that
7745 * has the same data as @parent_bs. If so, return @node_name's BDS;
7748 * @node_name must be a (recursive) *child of @parent_bs (or this
7749 * function will return NULL).
7751 * The result (whether the node can be replaced or not) is only valid
7752 * for as long as no graph or permission changes occur.
7754 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
7755 const char *node_name, Error **errp)
7757 BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
7758 AioContext *aio_context;
7760 GLOBAL_STATE_CODE();
7762 if (!to_replace_bs) {
7763 error_setg(errp, "Failed to find node with node-name='%s'", node_name);
7767 aio_context = bdrv_get_aio_context(to_replace_bs);
7768 aio_context_acquire(aio_context);
7770 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
7771 to_replace_bs = NULL;
7775 /* We don't want arbitrary node of the BDS chain to be replaced only the top
7776 * most non filter in order to prevent data corruption.
7777 * Another benefit is that this tests exclude backing files which are
7778 * blocked by the backing blockers.
7780 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) {
7781 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', "
7782 "because it cannot be guaranteed that doing so would not "
7783 "lead to an abrupt change of visible data",
7784 node_name, parent_bs->node_name);
7785 to_replace_bs = NULL;
7790 aio_context_release(aio_context);
7791 return to_replace_bs;
7795 * Iterates through the list of runtime option keys that are said to
7796 * be "strong" for a BDS. An option is called "strong" if it changes
7797 * a BDS's data. For example, the null block driver's "size" and
7798 * "read-zeroes" options are strong, but its "latency-ns" option is
7801 * If a key returned by this function ends with a dot, all options
7802 * starting with that prefix are strong.
7804 static const char *const *strong_options(BlockDriverState *bs,
7805 const char *const *curopt)
7807 static const char *const global_options[] = {
7808 "driver", "filename", NULL
7812 return &global_options[0];
7816 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
7817 curopt = bs->drv->strong_runtime_opts;
7820 return (curopt && *curopt) ? curopt : NULL;
7824 * Copies all strong runtime options from bs->options to the given
7825 * QDict. The set of strong option keys is determined by invoking
7828 * Returns true iff any strong option was present in bs->options (and
7829 * thus copied to the target QDict) with the exception of "filename"
7830 * and "driver". The caller is expected to use this value to decide
7831 * whether the existence of strong options prevents the generation of
7834 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
7836 bool found_any = false;
7837 const char *const *option_name = NULL;
7843 while ((option_name = strong_options(bs, option_name))) {
7844 bool option_given = false;
7846 assert(strlen(*option_name) > 0);
7847 if ((*option_name)[strlen(*option_name) - 1] != '.') {
7848 QObject *entry = qdict_get(bs->options, *option_name);
7853 qdict_put_obj(d, *option_name, qobject_ref(entry));
7854 option_given = true;
7856 const QDictEntry *entry;
7857 for (entry = qdict_first(bs->options); entry;
7858 entry = qdict_next(bs->options, entry))
7860 if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
7861 qdict_put_obj(d, qdict_entry_key(entry),
7862 qobject_ref(qdict_entry_value(entry)));
7863 option_given = true;
7868 /* While "driver" and "filename" need to be included in a JSON filename,
7869 * their existence does not prohibit generation of a plain filename. */
7870 if (!found_any && option_given &&
7871 strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
7877 if (!qdict_haskey(d, "driver")) {
7878 /* Drivers created with bdrv_new_open_driver() may not have a
7879 * @driver option. Add it here. */
7880 qdict_put_str(d, "driver", bs->drv->format_name);
7886 /* Note: This function may return false positives; it may return true
7887 * even if opening the backing file specified by bs's image header
7888 * would result in exactly bs->backing. */
7889 static bool bdrv_backing_overridden(BlockDriverState *bs)
7891 GLOBAL_STATE_CODE();
7893 return strcmp(bs->auto_backing_file,
7894 bs->backing->bs->filename);
7896 /* No backing BDS, so if the image header reports any backing
7897 * file, it must have been suppressed */
7898 return bs->auto_backing_file[0] != '\0';
7902 /* Updates the following BDS fields:
7903 * - exact_filename: A filename which may be used for opening a block device
7904 * which (mostly) equals the given BDS (even without any
7905 * other options; so reading and writing must return the same
7906 * results, but caching etc. may be different)
7907 * - full_open_options: Options which, when given when opening a block device
7908 * (without a filename), result in a BDS (mostly)
7909 * equalling the given one
7910 * - filename: If exact_filename is set, it is copied here. Otherwise,
7911 * full_open_options is converted to a JSON object, prefixed with
7912 * "json:" (for use through the JSON pseudo protocol) and put here.
7914 void bdrv_refresh_filename(BlockDriverState *bs)
7916 BlockDriver *drv = bs->drv;
7918 BlockDriverState *primary_child_bs;
7920 bool backing_overridden;
7921 bool generate_json_filename; /* Whether our default implementation should
7922 fill exact_filename (false) or not (true) */
7924 GLOBAL_STATE_CODE();
7930 /* This BDS's file name may depend on any of its children's file names, so
7931 * refresh those first */
7932 QLIST_FOREACH(child, &bs->children, next) {
7933 bdrv_refresh_filename(child->bs);
7937 /* For implicit nodes, just copy everything from the single child */
7938 child = QLIST_FIRST(&bs->children);
7939 assert(QLIST_NEXT(child, next) == NULL);
7941 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
7942 child->bs->exact_filename);
7943 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
7945 qobject_unref(bs->full_open_options);
7946 bs->full_open_options = qobject_ref(child->bs->full_open_options);
7951 backing_overridden = bdrv_backing_overridden(bs);
7953 if (bs->open_flags & BDRV_O_NO_IO) {
7954 /* Without I/O, the backing file does not change anything.
7955 * Therefore, in such a case (primarily qemu-img), we can
7956 * pretend the backing file has not been overridden even if
7957 * it technically has been. */
7958 backing_overridden = false;
7961 /* Gather the options QDict */
7963 generate_json_filename = append_strong_runtime_options(opts, bs);
7964 generate_json_filename |= backing_overridden;
7966 if (drv->bdrv_gather_child_options) {
7967 /* Some block drivers may not want to present all of their children's
7968 * options, or name them differently from BdrvChild.name */
7969 drv->bdrv_gather_child_options(bs, opts, backing_overridden);
7971 QLIST_FOREACH(child, &bs->children, next) {
7972 if (child == bs->backing && !backing_overridden) {
7973 /* We can skip the backing BDS if it has not been overridden */
7977 qdict_put(opts, child->name,
7978 qobject_ref(child->bs->full_open_options));
7981 if (backing_overridden && !bs->backing) {
7982 /* Force no backing file */
7983 qdict_put_null(opts, "backing");
7987 qobject_unref(bs->full_open_options);
7988 bs->full_open_options = opts;
7990 primary_child_bs = bdrv_primary_bs(bs);
7992 if (drv->bdrv_refresh_filename) {
7993 /* Obsolete information is of no use here, so drop the old file name
7994 * information before refreshing it */
7995 bs->exact_filename[0] = '\0';
7997 drv->bdrv_refresh_filename(bs);
7998 } else if (primary_child_bs) {
8000 * Try to reconstruct valid information from the underlying
8001 * file -- this only works for format nodes (filter nodes
8002 * cannot be probed and as such must be selected by the user
8003 * either through an options dict, or through a special
8004 * filename which the filter driver must construct in its
8005 * .bdrv_refresh_filename() implementation).
8008 bs->exact_filename[0] = '\0';
8011 * We can use the underlying file's filename if:
8012 * - it has a filename,
8013 * - the current BDS is not a filter,
8014 * - the file is a protocol BDS, and
8015 * - opening that file (as this BDS's format) will automatically create
8016 * the BDS tree we have right now, that is:
8017 * - the user did not significantly change this BDS's behavior with
8018 * some explicit (strong) options
8019 * - no non-file child of this BDS has been overridden by the user
8020 * Both of these conditions are represented by generate_json_filename.
8022 if (primary_child_bs->exact_filename[0] &&
8023 primary_child_bs->drv->bdrv_file_open &&
8024 !drv->is_filter && !generate_json_filename)
8026 strcpy(bs->exact_filename, primary_child_bs->exact_filename);
8030 if (bs->exact_filename[0]) {
8031 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
8033 GString *json = qobject_to_json(QOBJECT(bs->full_open_options));
8034 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s",
8035 json->str) >= sizeof(bs->filename)) {
8036 /* Give user a hint if we truncated things. */
8037 strcpy(bs->filename + sizeof(bs->filename) - 4, "...");
8039 g_string_free(json, true);
8043 char *bdrv_dirname(BlockDriverState *bs, Error **errp)
8045 BlockDriver *drv = bs->drv;
8046 BlockDriverState *child_bs;
8048 GLOBAL_STATE_CODE();
8051 error_setg(errp, "Node '%s' is ejected", bs->node_name);
8055 if (drv->bdrv_dirname) {
8056 return drv->bdrv_dirname(bs, errp);
8059 child_bs = bdrv_primary_bs(bs);
8061 return bdrv_dirname(child_bs, errp);
8064 bdrv_refresh_filename(bs);
8065 if (bs->exact_filename[0] != '\0') {
8066 return path_combine(bs->exact_filename, "");
8069 error_setg(errp, "Cannot generate a base directory for %s nodes",
8075 * Hot add/remove a BDS's child. So the user can take a child offline when
8076 * it is broken and take a new child online
8078 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
8081 GLOBAL_STATE_CODE();
8082 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
8083 error_setg(errp, "The node %s does not support adding a child",
8084 bdrv_get_device_or_node_name(parent_bs));
8089 * Non-zoned block drivers do not follow zoned storage constraints
8090 * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
8091 * drivers in a graph.
8093 if (!parent_bs->drv->supports_zoned_children &&
8094 child_bs->bl.zoned == BLK_Z_HM) {
8096 * The host-aware model allows zoned storage constraints and random
8097 * write. Allow mixing host-aware and non-zoned drivers. Using
8098 * host-aware device as a regular device.
8100 error_setg(errp, "Cannot add a %s child to a %s parent",
8101 child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned",
8102 parent_bs->drv->supports_zoned_children ?
8103 "support zoned children" : "not support zoned children");
8107 if (!QLIST_EMPTY(&child_bs->parents)) {
8108 error_setg(errp, "The node %s already has a parent",
8109 child_bs->node_name);
8113 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
8116 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
8120 GLOBAL_STATE_CODE();
8121 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
8122 error_setg(errp, "The node %s does not support removing a child",
8123 bdrv_get_device_or_node_name(parent_bs));
8127 QLIST_FOREACH(tmp, &parent_bs->children, next) {
8134 error_setg(errp, "The node %s does not have a child named %s",
8135 bdrv_get_device_or_node_name(parent_bs),
8136 bdrv_get_device_or_node_name(child->bs));
8140 parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
8143 int bdrv_make_empty(BdrvChild *c, Error **errp)
8145 BlockDriver *drv = c->bs->drv;
8148 GLOBAL_STATE_CODE();
8149 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED));
8151 if (!drv->bdrv_make_empty) {
8152 error_setg(errp, "%s does not support emptying nodes",
8157 ret = drv->bdrv_make_empty(c->bs);
8159 error_setg_errno(errp, -ret, "Failed to empty %s",
8168 * Return the child that @bs acts as an overlay for, and from which data may be
8169 * copied in COW or COR operations. Usually this is the backing file.
8171 BdrvChild *bdrv_cow_child(BlockDriverState *bs)
8175 if (!bs || !bs->drv) {
8179 if (bs->drv->is_filter) {
8187 assert(bs->backing->role & BDRV_CHILD_COW);
8192 * If @bs acts as a filter for exactly one of its children, return
8195 BdrvChild *bdrv_filter_child(BlockDriverState *bs)
8200 if (!bs || !bs->drv) {
8204 if (!bs->drv->is_filter) {
8208 /* Only one of @backing or @file may be used */
8209 assert(!(bs->backing && bs->file));
8211 c = bs->backing ?: bs->file;
8216 assert(c->role & BDRV_CHILD_FILTERED);
8221 * Return either the result of bdrv_cow_child() or bdrv_filter_child(),
8222 * whichever is non-NULL.
8224 * Return NULL if both are NULL.
8226 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs)
8228 BdrvChild *cow_child = bdrv_cow_child(bs);
8229 BdrvChild *filter_child = bdrv_filter_child(bs);
8232 /* Filter nodes cannot have COW backing files */
8233 assert(!(cow_child && filter_child));
8235 return cow_child ?: filter_child;
8239 * Return the primary child of this node: For filters, that is the
8240 * filtered child. For other nodes, that is usually the child storing
8242 * (A generally more helpful description is that this is (usually) the
8243 * child that has the same filename as @bs.)
8245 * Drivers do not necessarily have a primary child; for example quorum
8248 BdrvChild *bdrv_primary_child(BlockDriverState *bs)
8250 BdrvChild *c, *found = NULL;
8253 QLIST_FOREACH(c, &bs->children, next) {
8254 if (c->role & BDRV_CHILD_PRIMARY) {
8263 static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs,
8264 bool stop_on_explicit_filter)
8272 while (!(stop_on_explicit_filter && !bs->implicit)) {
8273 c = bdrv_filter_child(bs);
8276 * A filter that is embedded in a working block graph must
8277 * have a child. Assert this here so this function does
8278 * not return a filter node that is not expected by the
8281 assert(!bs->drv || !bs->drv->is_filter);
8287 * Note that this treats nodes with bs->drv == NULL as not being
8288 * filters (bs->drv == NULL should be replaced by something else
8290 * The advantage of this behavior is that this function will thus
8291 * always return a non-NULL value (given a non-NULL @bs).
8298 * Return the first BDS that has not been added implicitly or that
8299 * does not have a filtered child down the chain starting from @bs
8300 * (including @bs itself).
8302 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
8304 GLOBAL_STATE_CODE();
8305 return bdrv_do_skip_filters(bs, true);
8309 * Return the first BDS that does not have a filtered child down the
8310 * chain starting from @bs (including @bs itself).
8312 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
8315 return bdrv_do_skip_filters(bs, false);
8319 * For a backing chain, return the first non-filter backing image of
8320 * the first non-filter image.
8322 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
8325 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));
8329 * Check whether [offset, offset + bytes) overlaps with the cached
8330 * block-status data region.
8332 * If so, and @pnum is not NULL, set *pnum to `bsc.data_end - offset`,
8333 * which is what bdrv_bsc_is_data()'s interface needs.
8334 * Otherwise, *pnum is not touched.
8336 static bool bdrv_bsc_range_overlaps_locked(BlockDriverState *bs,
8337 int64_t offset, int64_t bytes,
8340 BdrvBlockStatusCache *bsc = qatomic_rcu_read(&bs->block_status_cache);
8344 qatomic_read(&bsc->valid) &&
8345 ranges_overlap(offset, bytes, bsc->data_start,
8346 bsc->data_end - bsc->data_start);
8348 if (overlaps && pnum) {
8349 *pnum = bsc->data_end - offset;
8356 * See block_int.h for this function's documentation.
8358 bool bdrv_bsc_is_data(BlockDriverState *bs, int64_t offset, int64_t *pnum)
8361 RCU_READ_LOCK_GUARD();
8362 return bdrv_bsc_range_overlaps_locked(bs, offset, 1, pnum);
8366 * See block_int.h for this function's documentation.
8368 void bdrv_bsc_invalidate_range(BlockDriverState *bs,
8369 int64_t offset, int64_t bytes)
8372 RCU_READ_LOCK_GUARD();
8374 if (bdrv_bsc_range_overlaps_locked(bs, offset, bytes, NULL)) {
8375 qatomic_set(&bs->block_status_cache->valid, false);
8380 * See block_int.h for this function's documentation.
8382 void bdrv_bsc_fill(BlockDriverState *bs, int64_t offset, int64_t bytes)
8384 BdrvBlockStatusCache *new_bsc = g_new(BdrvBlockStatusCache, 1);
8385 BdrvBlockStatusCache *old_bsc;
8388 *new_bsc = (BdrvBlockStatusCache) {
8390 .data_start = offset,
8391 .data_end = offset + bytes,
8394 QEMU_LOCK_GUARD(&bs->bsc_modify_lock);
8396 old_bsc = qatomic_rcu_read(&bs->block_status_cache);
8397 qatomic_rcu_set(&bs->block_status_cache, new_bsc);
8399 g_free_rcu(old_bsc, rcu);