qemu

blockdev.c (119119B)

---

 /*
  * QEMU host block devices
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or
  * later.  See the COPYING file in the top-level directory.
  *
  * This file incorporates work covered by the following copyright and
  * permission notice:
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 
 #include "qemu/osdep.h"
 #include "sysemu/block-backend.h"
 #include "sysemu/blockdev.h"
 #include "hw/block/block.h"
 #include "block/blockjob.h"
 #include "block/qdict.h"
 #include "block/throttle-groups.h"
 #include "monitor/monitor.h"
 #include "qemu/error-report.h"
 #include "qemu/option.h"
 #include "qemu/qemu-print.h"
 #include "qemu/config-file.h"
 #include "qapi/qapi-commands-block.h"
 #include "qapi/qapi-commands-transaction.h"
 #include "qapi/qapi-visit-block-core.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qnum.h"
 #include "qapi/qmp/qstring.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qerror.h"
 #include "qapi/qmp/qlist.h"
 #include "qapi/qobject-output-visitor.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/iothread.h"
 #include "block/block_int.h"
 #include "block/trace.h"
 #include "sysemu/runstate.h"
 #include "sysemu/replay.h"
 #include "qemu/cutils.h"
 #include "qemu/help_option.h"
 #include "qemu/main-loop.h"
 #include "qemu/throttle-options.h"
 
 /* Protected by BQL */
 QTAILQ_HEAD(, BlockDriverState) monitor_bdrv_states =
     QTAILQ_HEAD_INITIALIZER(monitor_bdrv_states);
 
 void bdrv_set_monitor_owned(BlockDriverState *bs)
 {
     GLOBAL_STATE_CODE();
     QTAILQ_INSERT_TAIL(&monitor_bdrv_states, bs, monitor_list);
 }
 
 static const char *const if_name[IF_COUNT] = {
     [IF_NONE] = "none",
     [IF_IDE] = "ide",
     [IF_SCSI] = "scsi",
     [IF_FLOPPY] = "floppy",
     [IF_PFLASH] = "pflash",
     [IF_MTD] = "mtd",
     [IF_SD] = "sd",
     [IF_VIRTIO] = "virtio",
     [IF_XEN] = "xen",
 };
 
 static int if_max_devs[IF_COUNT] = {
     /*
      * Do not change these numbers!  They govern how drive option
      * index maps to unit and bus.  That mapping is ABI.
      *
      * All controllers used to implement if=T drives need to support
      * if_max_devs[T] units, for any T with if_max_devs[T] != 0.
      * Otherwise, some index values map to "impossible" bus, unit
      * values.
      *
      * For instance, if you change [IF_SCSI] to 255, -drive
      * if=scsi,index=12 no longer means bus=1,unit=5, but
      * bus=0,unit=12.  With an lsi53c895a controller (7 units max),
      * the drive can't be set up.  Regression.
      */
     [IF_IDE] = 2,
     [IF_SCSI] = 7,
 };
 
 /**
  * Boards may call this to offer board-by-board overrides
  * of the default, global values.
  */
 void override_max_devs(BlockInterfaceType type, int max_devs)
 {
     BlockBackend *blk;
     DriveInfo *dinfo;
 
     GLOBAL_STATE_CODE();
 
     if (max_devs <= 0) {
         return;
     }
 
     for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
         dinfo = blk_legacy_dinfo(blk);
         if (dinfo->type == type) {
             fprintf(stderr, "Cannot override units-per-bus property of"
                     " the %s interface, because a drive of that type has"
                     " already been added.\n", if_name[type]);
             g_assert_not_reached();
         }
     }
 
     if_max_devs[type] = max_devs;
 }
 
 /*
  * We automatically delete the drive when a device using it gets
  * unplugged.  Questionable feature, but we can't just drop it.
  * Device models call blockdev_mark_auto_del() to schedule the
  * automatic deletion, and generic qdev code calls blockdev_auto_del()
  * when deletion is actually safe.
  */
 void blockdev_mark_auto_del(BlockBackend *blk)
 {
     DriveInfo *dinfo = blk_legacy_dinfo(blk);
     BlockJob *job;
 
     GLOBAL_STATE_CODE();
 
     if (!dinfo) {
         return;
     }
 
     JOB_LOCK_GUARD();
 
     for (job = block_job_next_locked(NULL); job;
          job = block_job_next_locked(job)) {
         if (block_job_has_bdrv(job, blk_bs(blk))) {
             job_cancel_locked(&job->job, false);
         }
     }
 
     dinfo->auto_del = 1;
 }
 
 void blockdev_auto_del(BlockBackend *blk)
 {
     DriveInfo *dinfo = blk_legacy_dinfo(blk);
     GLOBAL_STATE_CODE();
 
     if (dinfo && dinfo->auto_del) {
         monitor_remove_blk(blk);
         blk_unref(blk);
     }
 }
 
 static int drive_index_to_bus_id(BlockInterfaceType type, int index)
 {
     int max_devs = if_max_devs[type];
     return max_devs ? index / max_devs : 0;
 }
 
 static int drive_index_to_unit_id(BlockInterfaceType type, int index)
 {
     int max_devs = if_max_devs[type];
     return max_devs ? index % max_devs : index;
 }
 
 QemuOpts *drive_add(BlockInterfaceType type, int index, const char *file,
                     const char *optstr)
 {
     QemuOpts *opts;
 
     GLOBAL_STATE_CODE();
 
     opts = qemu_opts_parse_noisily(qemu_find_opts("drive"), optstr, false);
     if (!opts) {
         return NULL;
     }
     if (type != IF_DEFAULT) {
         qemu_opt_set(opts, "if", if_name[type], &error_abort);
     }
     if (index >= 0) {
         qemu_opt_set_number(opts, "index", index, &error_abort);
     }
     if (file)
         qemu_opt_set(opts, "file", file, &error_abort);
     return opts;
 }
 
 DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit)
 {
     BlockBackend *blk;
     DriveInfo *dinfo;
 
     GLOBAL_STATE_CODE();
 
     for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
         dinfo = blk_legacy_dinfo(blk);
         if (dinfo && dinfo->type == type
             && dinfo->bus == bus && dinfo->unit == unit) {
             return dinfo;
         }
     }
 
     return NULL;
 }
 
 /*
  * Check board claimed all -drive that are meant to be claimed.
  * Fatal error if any remain unclaimed.
  */
 void drive_check_orphaned(void)
 {
     BlockBackend *blk;
     DriveInfo *dinfo;
     Location loc;
     bool orphans = false;
 
     GLOBAL_STATE_CODE();
 
     for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
         dinfo = blk_legacy_dinfo(blk);
         /*
          * Ignore default drives, because we create certain default
          * drives unconditionally, then leave them unclaimed.  Not the
          * users fault.
          * Ignore IF_VIRTIO, because it gets desugared into -device,
          * so we can leave failing to -device.
          * Ignore IF_NONE, because leaving unclaimed IF_NONE remains
          * available for device_add is a feature.
          */
         if (dinfo->is_default || dinfo->type == IF_VIRTIO
             || dinfo->type == IF_NONE) {
             continue;
         }
         if (!blk_get_attached_dev(blk)) {
             loc_push_none(&loc);
             qemu_opts_loc_restore(dinfo->opts);
             error_report("machine type does not support"
                          " if=%s,bus=%d,unit=%d",
                          if_name[dinfo->type], dinfo->bus, dinfo->unit);
             loc_pop(&loc);
             orphans = true;
         }
     }
 
     if (orphans) {
         exit(1);
     }
 }
 
 DriveInfo *drive_get_by_index(BlockInterfaceType type, int index)
 {
     GLOBAL_STATE_CODE();
     return drive_get(type,
                      drive_index_to_bus_id(type, index),
                      drive_index_to_unit_id(type, index));
 }
 
 int drive_get_max_bus(BlockInterfaceType type)
 {
     int max_bus;
     BlockBackend *blk;
     DriveInfo *dinfo;
 
     GLOBAL_STATE_CODE();
 
     max_bus = -1;
     for (blk = blk_next(NULL); blk; blk = blk_next(blk)) {
         dinfo = blk_legacy_dinfo(blk);
         if (dinfo && dinfo->type == type && dinfo->bus > max_bus) {
             max_bus = dinfo->bus;
         }
     }
     return max_bus;
 }
 
 static void bdrv_format_print(void *opaque, const char *name)
 {
     qemu_printf(" %s", name);
 }
 
 typedef struct {
     QEMUBH *bh;
     BlockDriverState *bs;
 } BDRVPutRefBH;
 
 static int parse_block_error_action(const char *buf, bool is_read, Error **errp)
 {
     if (!strcmp(buf, "ignore")) {
         return BLOCKDEV_ON_ERROR_IGNORE;
     } else if (!is_read && !strcmp(buf, "enospc")) {
         return BLOCKDEV_ON_ERROR_ENOSPC;
     } else if (!strcmp(buf, "stop")) {
         return BLOCKDEV_ON_ERROR_STOP;
     } else if (!strcmp(buf, "report")) {
         return BLOCKDEV_ON_ERROR_REPORT;
     } else {
         error_setg(errp, "'%s' invalid %s error action",
                    buf, is_read ? "read" : "write");
         return -1;
     }
 }
 
 static bool parse_stats_intervals(BlockAcctStats *stats, QList *intervals,
                                   Error **errp)
 {
     const QListEntry *entry;
     for (entry = qlist_first(intervals); entry; entry = qlist_next(entry)) {
         switch (qobject_type(entry->value)) {
 
         case QTYPE_QSTRING: {
             unsigned long long length;
             const char *str = qstring_get_str(qobject_to(QString,
                                                          entry->value));
             if (parse_uint_full(str, &length, 10) == 0 &&
                 length > 0 && length <= UINT_MAX) {
                 block_acct_add_interval(stats, (unsigned) length);
             } else {
                 error_setg(errp, "Invalid interval length: %s", str);
                 return false;
             }
             break;
         }
 
         case QTYPE_QNUM: {
             int64_t length = qnum_get_int(qobject_to(QNum, entry->value));
 
             if (length > 0 && length <= UINT_MAX) {
                 block_acct_add_interval(stats, (unsigned) length);
             } else {
                 error_setg(errp, "Invalid interval length: %" PRId64, length);
                 return false;
             }
             break;
         }
 
         default:
             error_setg(errp, "The specification of stats-intervals is invalid");
             return false;
         }
     }
     return true;
 }
 
 typedef enum { MEDIA_DISK, MEDIA_CDROM } DriveMediaType;
 
 /* All parameters but @opts are optional and may be set to NULL. */
 static void extract_common_blockdev_options(QemuOpts *opts, int *bdrv_flags,
     const char **throttling_group, ThrottleConfig *throttle_cfg,
     BlockdevDetectZeroesOptions *detect_zeroes, Error **errp)
 {
     Error *local_error = NULL;
     const char *aio;
 
     if (bdrv_flags) {
         if (qemu_opt_get_bool(opts, "copy-on-read", false)) {
             *bdrv_flags |= BDRV_O_COPY_ON_READ;
         }
 
         if ((aio = qemu_opt_get(opts, "aio")) != NULL) {
             if (bdrv_parse_aio(aio, bdrv_flags) < 0) {
                 error_setg(errp, "invalid aio option");
                 return;
             }
         }
     }
 
     /* disk I/O throttling */
     if (throttling_group) {
         *throttling_group = qemu_opt_get(opts, "throttling.group");
     }
 
     if (throttle_cfg) {
         throttle_config_init(throttle_cfg);
         throttle_cfg->buckets[THROTTLE_BPS_TOTAL].avg =
             qemu_opt_get_number(opts, "throttling.bps-total", 0);
         throttle_cfg->buckets[THROTTLE_BPS_READ].avg  =
             qemu_opt_get_number(opts, "throttling.bps-read", 0);
         throttle_cfg->buckets[THROTTLE_BPS_WRITE].avg =
             qemu_opt_get_number(opts, "throttling.bps-write", 0);
         throttle_cfg->buckets[THROTTLE_OPS_TOTAL].avg =
             qemu_opt_get_number(opts, "throttling.iops-total", 0);
         throttle_cfg->buckets[THROTTLE_OPS_READ].avg =
             qemu_opt_get_number(opts, "throttling.iops-read", 0);
         throttle_cfg->buckets[THROTTLE_OPS_WRITE].avg =
             qemu_opt_get_number(opts, "throttling.iops-write", 0);
 
         throttle_cfg->buckets[THROTTLE_BPS_TOTAL].max =
             qemu_opt_get_number(opts, "throttling.bps-total-max", 0);
         throttle_cfg->buckets[THROTTLE_BPS_READ].max  =
             qemu_opt_get_number(opts, "throttling.bps-read-max", 0);
         throttle_cfg->buckets[THROTTLE_BPS_WRITE].max =
             qemu_opt_get_number(opts, "throttling.bps-write-max", 0);
         throttle_cfg->buckets[THROTTLE_OPS_TOTAL].max =
             qemu_opt_get_number(opts, "throttling.iops-total-max", 0);
         throttle_cfg->buckets[THROTTLE_OPS_READ].max =
             qemu_opt_get_number(opts, "throttling.iops-read-max", 0);
         throttle_cfg->buckets[THROTTLE_OPS_WRITE].max =
             qemu_opt_get_number(opts, "throttling.iops-write-max", 0);
 
         throttle_cfg->buckets[THROTTLE_BPS_TOTAL].burst_length =
             qemu_opt_get_number(opts, "throttling.bps-total-max-length", 1);
         throttle_cfg->buckets[THROTTLE_BPS_READ].burst_length  =
             qemu_opt_get_number(opts, "throttling.bps-read-max-length", 1);
         throttle_cfg->buckets[THROTTLE_BPS_WRITE].burst_length =
             qemu_opt_get_number(opts, "throttling.bps-write-max-length", 1);
         throttle_cfg->buckets[THROTTLE_OPS_TOTAL].burst_length =
             qemu_opt_get_number(opts, "throttling.iops-total-max-length", 1);
         throttle_cfg->buckets[THROTTLE_OPS_READ].burst_length =
             qemu_opt_get_number(opts, "throttling.iops-read-max-length", 1);
         throttle_cfg->buckets[THROTTLE_OPS_WRITE].burst_length =
             qemu_opt_get_number(opts, "throttling.iops-write-max-length", 1);
 
         throttle_cfg->op_size =
             qemu_opt_get_number(opts, "throttling.iops-size", 0);
 
         if (!throttle_is_valid(throttle_cfg, errp)) {
             return;
         }
     }
 
     if (detect_zeroes) {
         *detect_zeroes =
             qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup,
                             qemu_opt_get(opts, "detect-zeroes"),
                             BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
                             &local_error);
         if (local_error) {
             error_propagate(errp, local_error);
             return;
         }
     }
 }
 
 static OnOffAuto account_get_opt(QemuOpts *opts, const char *name)
 {
     if (!qemu_opt_find(opts, name)) {
         return ON_OFF_AUTO_AUTO;
     }
     if (qemu_opt_get_bool(opts, name, true)) {
         return ON_OFF_AUTO_ON;
     }
     return ON_OFF_AUTO_OFF;
 }
 
 /* Takes the ownership of bs_opts */
 static BlockBackend *blockdev_init(const char *file, QDict *bs_opts,
                                    Error **errp)
 {
     const char *buf;
     int bdrv_flags = 0;
     int on_read_error, on_write_error;
     OnOffAuto account_invalid, account_failed;
     bool writethrough, read_only;
     BlockBackend *blk;
     BlockDriverState *bs;
     ThrottleConfig cfg;
     int snapshot = 0;
     Error *error = NULL;
     QemuOpts *opts;
     QDict *interval_dict = NULL;
     QList *interval_list = NULL;
     const char *id;
     BlockdevDetectZeroesOptions detect_zeroes =
         BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF;
     const char *throttling_group = NULL;
 
     /* Check common options by copying from bs_opts to opts, all other options
      * stay in bs_opts for processing by bdrv_open(). */
     id = qdict_get_try_str(bs_opts, "id");
     opts = qemu_opts_create(&qemu_common_drive_opts, id, 1, errp);
     if (!opts) {
         goto err_no_opts;
     }
 
     if (!qemu_opts_absorb_qdict(opts, bs_opts, errp)) {
         goto early_err;
     }
 
     if (id) {
         qdict_del(bs_opts, "id");
     }
 
     /* extract parameters */
     snapshot = qemu_opt_get_bool(opts, "snapshot", 0);
 
     account_invalid = account_get_opt(opts, "stats-account-invalid");
     account_failed = account_get_opt(opts, "stats-account-failed");
 
     writethrough = !qemu_opt_get_bool(opts, BDRV_OPT_CACHE_WB, true);
 
     id = qemu_opts_id(opts);
 
     qdict_extract_subqdict(bs_opts, &interval_dict, "stats-intervals.");
     qdict_array_split(interval_dict, &interval_list);
 
     if (qdict_size(interval_dict) != 0) {
         error_setg(errp, "Invalid option stats-intervals.%s",
                    qdict_first(interval_dict)->key);
         goto early_err;
     }
 
     extract_common_blockdev_options(opts, &bdrv_flags, &throttling_group, &cfg,
                                     &detect_zeroes, &error);
     if (error) {
         error_propagate(errp, error);
         goto early_err;
     }
 
     if ((buf = qemu_opt_get(opts, "format")) != NULL) {
         if (is_help_option(buf)) {
             qemu_printf("Supported formats:");
             bdrv_iterate_format(bdrv_format_print, NULL, false);
             qemu_printf("\nSupported formats (read-only):");
             bdrv_iterate_format(bdrv_format_print, NULL, true);
             qemu_printf("\n");
             goto early_err;
         }
 
         if (qdict_haskey(bs_opts, "driver")) {
             error_setg(errp, "Cannot specify both 'driver' and 'format'");
             goto early_err;
         }
         qdict_put_str(bs_opts, "driver", buf);
     }
 
     on_write_error = BLOCKDEV_ON_ERROR_ENOSPC;
     if ((buf = qemu_opt_get(opts, "werror")) != NULL) {
         on_write_error = parse_block_error_action(buf, 0, &error);
         if (error) {
             error_propagate(errp, error);
             goto early_err;
         }
     }
 
     on_read_error = BLOCKDEV_ON_ERROR_REPORT;
     if ((buf = qemu_opt_get(opts, "rerror")) != NULL) {
         on_read_error = parse_block_error_action(buf, 1, &error);
         if (error) {
             error_propagate(errp, error);
             goto early_err;
         }
     }
 
     if (snapshot) {
         bdrv_flags |= BDRV_O_SNAPSHOT;
     }
 
     read_only = qemu_opt_get_bool(opts, BDRV_OPT_READ_ONLY, false);
 
     /* init */
     if ((!file || !*file) && !qdict_size(bs_opts)) {
         BlockBackendRootState *blk_rs;
 
         blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
         blk_rs = blk_get_root_state(blk);
         blk_rs->open_flags    = bdrv_flags | (read_only ? 0 : BDRV_O_RDWR);
         blk_rs->detect_zeroes = detect_zeroes;
 
         qobject_unref(bs_opts);
     } else {
         if (file && !*file) {
             file = NULL;
         }
 
         /* bdrv_open() defaults to the values in bdrv_flags (for compatibility
          * with other callers) rather than what we want as the real defaults.
          * Apply the defaults here instead. */
         qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_DIRECT, "off");
         qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, "off");
         qdict_set_default_str(bs_opts, BDRV_OPT_READ_ONLY,
                               read_only ? "on" : "off");
         qdict_set_default_str(bs_opts, BDRV_OPT_AUTO_READ_ONLY, "on");
         assert((bdrv_flags & BDRV_O_CACHE_MASK) == 0);
 
         if (runstate_check(RUN_STATE_INMIGRATE)) {
             bdrv_flags |= BDRV_O_INACTIVE;
         }
 
         blk = blk_new_open(file, NULL, bs_opts, bdrv_flags, errp);
         if (!blk) {
             goto err_no_bs_opts;
         }
         bs = blk_bs(blk);
 
         bs->detect_zeroes = detect_zeroes;
 
         block_acct_setup(blk_get_stats(blk), account_invalid, account_failed);
 
         if (!parse_stats_intervals(blk_get_stats(blk), interval_list, errp)) {
             blk_unref(blk);
             blk = NULL;
             goto err_no_bs_opts;
         }
     }
 
     /* disk I/O throttling */
     if (throttle_enabled(&cfg)) {
         if (!throttling_group) {
             throttling_group = id;
         }
         blk_io_limits_enable(blk, throttling_group);
         blk_set_io_limits(blk, &cfg);
     }
 
     blk_set_enable_write_cache(blk, !writethrough);
     blk_set_on_error(blk, on_read_error, on_write_error);
 
     if (!monitor_add_blk(blk, id, errp)) {
         blk_unref(blk);
         blk = NULL;
         goto err_no_bs_opts;
     }
 
 err_no_bs_opts:
     qemu_opts_del(opts);
     qobject_unref(interval_dict);
     qobject_unref(interval_list);
     return blk;
 
 early_err:
     qemu_opts_del(opts);
     qobject_unref(interval_dict);
     qobject_unref(interval_list);
 err_no_opts:
     qobject_unref(bs_opts);
     return NULL;
 }
 
 /* Takes the ownership of bs_opts */
 BlockDriverState *bds_tree_init(QDict *bs_opts, Error **errp)
 {
     int bdrv_flags = 0;
 
     GLOBAL_STATE_CODE();
     /* bdrv_open() defaults to the values in bdrv_flags (for compatibility
      * with other callers) rather than what we want as the real defaults.
      * Apply the defaults here instead. */
     qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_DIRECT, "off");
     qdict_set_default_str(bs_opts, BDRV_OPT_CACHE_NO_FLUSH, "off");
     qdict_set_default_str(bs_opts, BDRV_OPT_READ_ONLY, "off");
 
     if (runstate_check(RUN_STATE_INMIGRATE)) {
         bdrv_flags |= BDRV_O_INACTIVE;
     }
 
     return bdrv_open(NULL, NULL, bs_opts, bdrv_flags, errp);
 }
 
 void blockdev_close_all_bdrv_states(void)
 {
     BlockDriverState *bs, *next_bs;
 
     GLOBAL_STATE_CODE();
     QTAILQ_FOREACH_SAFE(bs, &monitor_bdrv_states, monitor_list, next_bs) {
         AioContext *ctx = bdrv_get_aio_context(bs);
 
         aio_context_acquire(ctx);
         bdrv_unref(bs);
         aio_context_release(ctx);
     }
 }
 
 /* Iterates over the list of monitor-owned BlockDriverStates */
 BlockDriverState *bdrv_next_monitor_owned(BlockDriverState *bs)
 {
     GLOBAL_STATE_CODE();
     return bs ? QTAILQ_NEXT(bs, monitor_list)
               : QTAILQ_FIRST(&monitor_bdrv_states);
 }
 
 static bool qemu_opt_rename(QemuOpts *opts, const char *from, const char *to,
                             Error **errp)
 {
     const char *value;
 
     value = qemu_opt_get(opts, from);
     if (value) {
         if (qemu_opt_find(opts, to)) {
             error_setg(errp, "'%s' and its alias '%s' can't be used at the "
                        "same time", to, from);
             return false;
         }
     }
 
     /* rename all items in opts */
     while ((value = qemu_opt_get(opts, from))) {
         qemu_opt_set(opts, to, value, &error_abort);
         qemu_opt_unset(opts, from);
     }
     return true;
 }
 
 QemuOptsList qemu_legacy_drive_opts = {
     .name = "drive",
     .head = QTAILQ_HEAD_INITIALIZER(qemu_legacy_drive_opts.head),
     .desc = {
         {
             .name = "bus",
             .type = QEMU_OPT_NUMBER,
             .help = "bus number",
         },{
             .name = "unit",
             .type = QEMU_OPT_NUMBER,
             .help = "unit number (i.e. lun for scsi)",
         },{
             .name = "index",
             .type = QEMU_OPT_NUMBER,
             .help = "index number",
         },{
             .name = "media",
             .type = QEMU_OPT_STRING,
             .help = "media type (disk, cdrom)",
         },{
             .name = "if",
             .type = QEMU_OPT_STRING,
             .help = "interface (ide, scsi, sd, mtd, floppy, pflash, virtio)",
         },{
             .name = "file",
             .type = QEMU_OPT_STRING,
             .help = "file name",
         },
 
         /* Options that are passed on, but have special semantics with -drive */
         {
             .name = BDRV_OPT_READ_ONLY,
             .type = QEMU_OPT_BOOL,
             .help = "open drive file as read-only",
         },{
             .name = "rerror",
             .type = QEMU_OPT_STRING,
             .help = "read error action",
         },{
             .name = "werror",
             .type = QEMU_OPT_STRING,
             .help = "write error action",
         },{
             .name = "copy-on-read",
             .type = QEMU_OPT_BOOL,
             .help = "copy read data from backing file into image file",
         },
 
         { /* end of list */ }
     },
 };
 
 DriveInfo *drive_new(QemuOpts *all_opts, BlockInterfaceType block_default_type,
                      Error **errp)
 {
     const char *value;
     BlockBackend *blk;
     DriveInfo *dinfo = NULL;
     QDict *bs_opts;
     QemuOpts *legacy_opts;
     DriveMediaType media = MEDIA_DISK;
     BlockInterfaceType type;
     int max_devs, bus_id, unit_id, index;
     const char *werror, *rerror;
     bool read_only = false;
     bool copy_on_read;
     const char *filename;
     int i;
 
     GLOBAL_STATE_CODE();
 
     /* Change legacy command line options into QMP ones */
     static const struct {
         const char *from;
         const char *to;
     } opt_renames[] = {
         { "iops",           "throttling.iops-total" },
         { "iops_rd",        "throttling.iops-read" },
         { "iops_wr",        "throttling.iops-write" },
 
         { "bps",            "throttling.bps-total" },
         { "bps_rd",         "throttling.bps-read" },
         { "bps_wr",         "throttling.bps-write" },
 
         { "iops_max",       "throttling.iops-total-max" },
         { "iops_rd_max",    "throttling.iops-read-max" },
         { "iops_wr_max",    "throttling.iops-write-max" },
 
         { "bps_max",        "throttling.bps-total-max" },
         { "bps_rd_max",     "throttling.bps-read-max" },
         { "bps_wr_max",     "throttling.bps-write-max" },
 
         { "iops_size",      "throttling.iops-size" },
 
         { "group",          "throttling.group" },
 
         { "readonly",       BDRV_OPT_READ_ONLY },
     };
 
     for (i = 0; i < ARRAY_SIZE(opt_renames); i++) {
         if (!qemu_opt_rename(all_opts, opt_renames[i].from,
                              opt_renames[i].to, errp)) {
             return NULL;
         }
     }
 
     value = qemu_opt_get(all_opts, "cache");
     if (value) {
         int flags = 0;
         bool writethrough;
 
         if (bdrv_parse_cache_mode(value, &flags, &writethrough) != 0) {
             error_setg(errp, "invalid cache option");
             return NULL;
         }
 
         /* Specific options take precedence */
         if (!qemu_opt_get(all_opts, BDRV_OPT_CACHE_WB)) {
             qemu_opt_set_bool(all_opts, BDRV_OPT_CACHE_WB,
                               !writethrough, &error_abort);
         }
         if (!qemu_opt_get(all_opts, BDRV_OPT_CACHE_DIRECT)) {
             qemu_opt_set_bool(all_opts, BDRV_OPT_CACHE_DIRECT,
                               !!(flags & BDRV_O_NOCACHE), &error_abort);
         }
         if (!qemu_opt_get(all_opts, BDRV_OPT_CACHE_NO_FLUSH)) {
             qemu_opt_set_bool(all_opts, BDRV_OPT_CACHE_NO_FLUSH,
                               !!(flags & BDRV_O_NO_FLUSH), &error_abort);
         }
         qemu_opt_unset(all_opts, "cache");
     }
 
     /* Get a QDict for processing the options */
     bs_opts = qdict_new();
     qemu_opts_to_qdict(all_opts, bs_opts);
 
     legacy_opts = qemu_opts_create(&qemu_legacy_drive_opts, NULL, 0,
                                    &error_abort);
     if (!qemu_opts_absorb_qdict(legacy_opts, bs_opts, errp)) {
         goto fail;
     }
 
     /* Media type */
     value = qemu_opt_get(legacy_opts, "media");
     if (value) {
         if (!strcmp(value, "disk")) {
             media = MEDIA_DISK;
         } else if (!strcmp(value, "cdrom")) {
             media = MEDIA_CDROM;
             read_only = true;
         } else {
             error_setg(errp, "'%s' invalid media", value);
             goto fail;
         }
     }
 
     /* copy-on-read is disabled with a warning for read-only devices */
     read_only |= qemu_opt_get_bool(legacy_opts, BDRV_OPT_READ_ONLY, false);
     copy_on_read = qemu_opt_get_bool(legacy_opts, "copy-on-read", false);
 
     if (read_only && copy_on_read) {
         warn_report("disabling copy-on-read on read-only drive");
         copy_on_read = false;
     }
 
     qdict_put_str(bs_opts, BDRV_OPT_READ_ONLY, read_only ? "on" : "off");
     qdict_put_str(bs_opts, "copy-on-read", copy_on_read ? "on" : "off");
 
     /* Controller type */
     value = qemu_opt_get(legacy_opts, "if");
     if (value) {
         for (type = 0;
              type < IF_COUNT && strcmp(value, if_name[type]);
              type++) {
         }
         if (type == IF_COUNT) {
             error_setg(errp, "unsupported bus type '%s'", value);
             goto fail;
         }
     } else {
         type = block_default_type;
     }
 
     /* Device address specified by bus/unit or index.
      * If none was specified, try to find the first free one. */
     bus_id  = qemu_opt_get_number(legacy_opts, "bus", 0);
     unit_id = qemu_opt_get_number(legacy_opts, "unit", -1);
     index   = qemu_opt_get_number(legacy_opts, "index", -1);
 
     max_devs = if_max_devs[type];
 
     if (index != -1) {
         if (bus_id != 0 || unit_id != -1) {
             error_setg(errp, "index cannot be used with bus and unit");
             goto fail;
         }
         bus_id = drive_index_to_bus_id(type, index);
         unit_id = drive_index_to_unit_id(type, index);
     }
 
     if (unit_id == -1) {
        unit_id = 0;
        while (drive_get(type, bus_id, unit_id) != NULL) {
            unit_id++;
            if (max_devs && unit_id >= max_devs) {
                unit_id -= max_devs;
                bus_id++;
            }
        }
     }
 
     if (max_devs && unit_id >= max_devs) {
         error_setg(errp, "unit %d too big (max is %d)", unit_id, max_devs - 1);
         goto fail;
     }
 
     if (drive_get(type, bus_id, unit_id) != NULL) {
         error_setg(errp, "drive with bus=%d, unit=%d (index=%d) exists",
                    bus_id, unit_id, index);
         goto fail;
     }
 
     /* no id supplied -> create one */
     if (qemu_opts_id(all_opts) == NULL) {
         char *new_id;
         const char *mediastr = "";
         if (type == IF_IDE || type == IF_SCSI) {
             mediastr = (media == MEDIA_CDROM) ? "-cd" : "-hd";
         }
         if (max_devs) {
             new_id = g_strdup_printf("%s%i%s%i", if_name[type], bus_id,
                                      mediastr, unit_id);
         } else {
             new_id = g_strdup_printf("%s%s%i", if_name[type],
                                      mediastr, unit_id);
         }
         qdict_put_str(bs_opts, "id", new_id);
         g_free(new_id);
     }
 
     /* Add virtio block device */
     if (type == IF_VIRTIO) {
         QemuOpts *devopts;
         devopts = qemu_opts_create(qemu_find_opts("device"), NULL, 0,
                                    &error_abort);
         qemu_opt_set(devopts, "driver", "virtio-blk", &error_abort);
         qemu_opt_set(devopts, "drive", qdict_get_str(bs_opts, "id"),
                      &error_abort);
     }
 
     filename = qemu_opt_get(legacy_opts, "file");
 
     /* Check werror/rerror compatibility with if=... */
     werror = qemu_opt_get(legacy_opts, "werror");
     if (werror != NULL) {
         if (type != IF_IDE && type != IF_SCSI && type != IF_VIRTIO &&
             type != IF_NONE) {
             error_setg(errp, "werror is not supported by this bus type");
             goto fail;
         }
         qdict_put_str(bs_opts, "werror", werror);
     }
 
     rerror = qemu_opt_get(legacy_opts, "rerror");
     if (rerror != NULL) {
         if (type != IF_IDE && type != IF_VIRTIO && type != IF_SCSI &&
             type != IF_NONE) {
             error_setg(errp, "rerror is not supported by this bus type");
             goto fail;
         }
         qdict_put_str(bs_opts, "rerror", rerror);
     }
 
     /* Actual block device init: Functionality shared with blockdev-add */
     blk = blockdev_init(filename, bs_opts, errp);
     bs_opts = NULL;
     if (!blk) {
         goto fail;
     }
 
     /* Create legacy DriveInfo */
     dinfo = g_malloc0(sizeof(*dinfo));
     dinfo->opts = all_opts;
 
     dinfo->type = type;
     dinfo->bus = bus_id;
     dinfo->unit = unit_id;
 
     blk_set_legacy_dinfo(blk, dinfo);
 
     switch(type) {
     case IF_IDE:
     case IF_SCSI:
     case IF_XEN:
     case IF_NONE:
         dinfo->media_cd = media == MEDIA_CDROM;
         break;
     default:
         break;
     }
 
 fail:
     qemu_opts_del(legacy_opts);
     qobject_unref(bs_opts);
     return dinfo;
 }
 
 static BlockDriverState *qmp_get_root_bs(const char *name, Error **errp)
 {
     BlockDriverState *bs;
 
     bs = bdrv_lookup_bs(name, name, errp);
     if (bs == NULL) {
         return NULL;
     }
 
     if (!bdrv_is_root_node(bs)) {
         error_setg(errp, "Need a root block node");
         return NULL;
     }
 
     if (!bdrv_is_inserted(bs)) {
         error_setg(errp, "Device has no medium");
         return NULL;
     }
 
     return bs;
 }
 
 static void blockdev_do_action(TransactionAction *action, Error **errp)
 {
     TransactionActionList list;
 
     list.value = action;
     list.next = NULL;
     qmp_transaction(&list, false, NULL, errp);
 }
 
 void qmp_blockdev_snapshot_sync(bool has_device, const char *device,
                                 bool has_node_name, const char *node_name,
                                 const char *snapshot_file,
                                 bool has_snapshot_node_name,
                                 const char *snapshot_node_name,
                                 bool has_format, const char *format,
                                 bool has_mode, NewImageMode mode, Error **errp)
 {
     BlockdevSnapshotSync snapshot = {
         .has_device = has_device,
         .device = (char *) device,
         .has_node_name = has_node_name,
         .node_name = (char *) node_name,
         .snapshot_file = (char *) snapshot_file,
         .has_snapshot_node_name = has_snapshot_node_name,
         .snapshot_node_name = (char *) snapshot_node_name,
         .has_format = has_format,
         .format = (char *) format,
         .has_mode = has_mode,
         .mode = mode,
     };
     TransactionAction action = {
         .type = TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC,
         .u.blockdev_snapshot_sync.data = &snapshot,
     };
     blockdev_do_action(&action, errp);
 }
 
 void qmp_blockdev_snapshot(const char *node, const char *overlay,
                            Error **errp)
 {
     BlockdevSnapshot snapshot_data = {
         .node = (char *) node,
         .overlay = (char *) overlay
     };
     TransactionAction action = {
         .type = TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT,
         .u.blockdev_snapshot.data = &snapshot_data,
     };
     blockdev_do_action(&action, errp);
 }
 
 void qmp_blockdev_snapshot_internal_sync(const char *device,
                                          const char *name,
                                          Error **errp)
 {
     BlockdevSnapshotInternal snapshot = {
         .device = (char *) device,
         .name = (char *) name
     };
     TransactionAction action = {
         .type = TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_INTERNAL_SYNC,
         .u.blockdev_snapshot_internal_sync.data = &snapshot,
     };
     blockdev_do_action(&action, errp);
 }
 
 SnapshotInfo *qmp_blockdev_snapshot_delete_internal_sync(const char *device,
                                                          bool has_id,
                                                          const char *id,
                                                          bool has_name,
                                                          const char *name,
                                                          Error **errp)
 {
     BlockDriverState *bs;
     AioContext *aio_context;
     QEMUSnapshotInfo sn;
     Error *local_err = NULL;
     SnapshotInfo *info = NULL;
     int ret;
 
     bs = qmp_get_root_bs(device, errp);
     if (!bs) {
         return NULL;
     }
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     if (!has_id) {
         id = NULL;
     }
 
     if (!has_name) {
         name = NULL;
     }
 
     if (!id && !name) {
         error_setg(errp, "Name or id must be provided");
         goto out_aio_context;
     }
 
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE, errp)) {
         goto out_aio_context;
     }
 
     ret = bdrv_snapshot_find_by_id_and_name(bs, id, name, &sn, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto out_aio_context;
     }
     if (!ret) {
         error_setg(errp,
                    "Snapshot with id '%s' and name '%s' does not exist on "
                    "device '%s'",
                    STR_OR_NULL(id), STR_OR_NULL(name), device);
         goto out_aio_context;
     }
 
     bdrv_snapshot_delete(bs, id, name, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto out_aio_context;
     }
 
     aio_context_release(aio_context);
 
     info = g_new0(SnapshotInfo, 1);
     info->id = g_strdup(sn.id_str);
     info->name = g_strdup(sn.name);
     info->date_nsec = sn.date_nsec;
     info->date_sec = sn.date_sec;
     info->vm_state_size = sn.vm_state_size;
     info->vm_clock_nsec = sn.vm_clock_nsec % 1000000000;
     info->vm_clock_sec = sn.vm_clock_nsec / 1000000000;
     if (sn.icount != -1ULL) {
         info->icount = sn.icount;
         info->has_icount = true;
     }
 
     return info;
 
 out_aio_context:
     aio_context_release(aio_context);
     return NULL;
 }
 
 /* New and old BlockDriverState structs for atomic group operations */
 
 typedef struct BlkActionState BlkActionState;
 
 /**
  * BlkActionOps:
  * Table of operations that define an Action.
  *
  * @instance_size: Size of state struct, in bytes.
  * @prepare: Prepare the work, must NOT be NULL.
  * @commit: Commit the changes, can be NULL.
  * @abort: Abort the changes on fail, can be NULL.
  * @clean: Clean up resources after all transaction actions have called
  *         commit() or abort(). Can be NULL.
  *
  * Only prepare() may fail. In a single transaction, only one of commit() or
  * abort() will be called. clean() will always be called if it is present.
  *
  * Always run under BQL.
  */
 typedef struct BlkActionOps {
     size_t instance_size;
     void (*prepare)(BlkActionState *common, Error **errp);
     void (*commit)(BlkActionState *common);
     void (*abort)(BlkActionState *common);
     void (*clean)(BlkActionState *common);
 } BlkActionOps;
 
 /**
  * BlkActionState:
  * Describes one Action's state within a Transaction.
  *
  * @action: QAPI-defined enum identifying which Action to perform.
  * @ops: Table of ActionOps this Action can perform.
  * @block_job_txn: Transaction which this action belongs to.
  * @entry: List membership for all Actions in this Transaction.
  *
  * This structure must be arranged as first member in a subclassed type,
  * assuming that the compiler will also arrange it to the same offsets as the
  * base class.
  */
 struct BlkActionState {
     TransactionAction *action;
     const BlkActionOps *ops;
     JobTxn *block_job_txn;
     TransactionProperties *txn_props;
     QTAILQ_ENTRY(BlkActionState) entry;
 };
 
 /* internal snapshot private data */
 typedef struct InternalSnapshotState {
     BlkActionState common;
     BlockDriverState *bs;
     QEMUSnapshotInfo sn;
     bool created;
 } InternalSnapshotState;
 
 
 static int action_check_completion_mode(BlkActionState *s, Error **errp)
 {
     if (s->txn_props->completion_mode != ACTION_COMPLETION_MODE_INDIVIDUAL) {
         error_setg(errp,
                    "Action '%s' does not support Transaction property "
                    "completion-mode = %s",
                    TransactionActionKind_str(s->action->type),
                    ActionCompletionMode_str(s->txn_props->completion_mode));
         return -1;
     }
     return 0;
 }
 
 static void internal_snapshot_prepare(BlkActionState *common,
                                       Error **errp)
 {
     Error *local_err = NULL;
     const char *device;
     const char *name;
     BlockDriverState *bs;
     QEMUSnapshotInfo old_sn, *sn;
     bool ret;
     int64_t rt;
     BlockdevSnapshotInternal *internal;
     InternalSnapshotState *state;
     AioContext *aio_context;
     int ret1;
 
     g_assert(common->action->type ==
              TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_INTERNAL_SYNC);
     internal = common->action->u.blockdev_snapshot_internal_sync.data;
     state = DO_UPCAST(InternalSnapshotState, common, common);
 
     /* 1. parse input */
     device = internal->device;
     name = internal->name;
 
     /* 2. check for validation */
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     bs = qmp_get_root_bs(device, errp);
     if (!bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     state->bs = bs;
 
     /* Paired with .clean() */
     bdrv_drained_begin(bs);
 
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT, errp)) {
         goto out;
     }
 
     if (bdrv_is_read_only(bs)) {
         error_setg(errp, "Device '%s' is read only", device);
         goto out;
     }
 
     if (!bdrv_can_snapshot(bs)) {
         error_setg(errp, "Block format '%s' used by device '%s' "
                    "does not support internal snapshots",
                    bs->drv->format_name, device);
         goto out;
     }
 
     if (!strlen(name)) {
         error_setg(errp, "Name is empty");
         goto out;
     }
 
     /* check whether a snapshot with name exist */
     ret = bdrv_snapshot_find_by_id_and_name(bs, NULL, name, &old_sn,
                                             &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto out;
     } else if (ret) {
         error_setg(errp,
                    "Snapshot with name '%s' already exists on device '%s'",
                    name, device);
         goto out;
     }
 
     /* 3. take the snapshot */
     sn = &state->sn;
     pstrcpy(sn->name, sizeof(sn->name), name);
     rt = g_get_real_time();
     sn->date_sec = rt / G_USEC_PER_SEC;
     sn->date_nsec = (rt % G_USEC_PER_SEC) * 1000;
     sn->vm_clock_nsec = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
     if (replay_mode != REPLAY_MODE_NONE) {
         sn->icount = replay_get_current_icount();
     } else {
         sn->icount = -1ULL;
     }
 
     ret1 = bdrv_snapshot_create(bs, sn);
     if (ret1 < 0) {
         error_setg_errno(errp, -ret1,
                          "Failed to create snapshot '%s' on device '%s'",
                          name, device);
         goto out;
     }
 
     /* 4. succeed, mark a snapshot is created */
     state->created = true;
 
 out:
     aio_context_release(aio_context);
 }
 
 static void internal_snapshot_abort(BlkActionState *common)
 {
     InternalSnapshotState *state =
                              DO_UPCAST(InternalSnapshotState, common, common);
     BlockDriverState *bs = state->bs;
     QEMUSnapshotInfo *sn = &state->sn;
     AioContext *aio_context;
     Error *local_error = NULL;
 
     if (!state->created) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(state->bs);
     aio_context_acquire(aio_context);
 
     if (bdrv_snapshot_delete(bs, sn->id_str, sn->name, &local_error) < 0) {
         error_reportf_err(local_error,
                           "Failed to delete snapshot with id '%s' and "
                           "name '%s' on device '%s' in abort: ",
                           sn->id_str, sn->name,
                           bdrv_get_device_name(bs));
     }
 
     aio_context_release(aio_context);
 }
 
 static void internal_snapshot_clean(BlkActionState *common)
 {
     InternalSnapshotState *state = DO_UPCAST(InternalSnapshotState,
                                              common, common);
     AioContext *aio_context;
 
     if (!state->bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(state->bs);
     aio_context_acquire(aio_context);
 
     bdrv_drained_end(state->bs);
 
     aio_context_release(aio_context);
 }
 
 /* external snapshot private data */
 typedef struct ExternalSnapshotState {
     BlkActionState common;
     BlockDriverState *old_bs;
     BlockDriverState *new_bs;
     bool overlay_appended;
 } ExternalSnapshotState;
 
 static void external_snapshot_prepare(BlkActionState *common,
                                       Error **errp)
 {
     int ret;
     int flags = 0;
     QDict *options = NULL;
     Error *local_err = NULL;
     /* Device and node name of the image to generate the snapshot from */
     const char *device;
     const char *node_name;
     /* Reference to the new image (for 'blockdev-snapshot') */
     const char *snapshot_ref;
     /* File name of the new image (for 'blockdev-snapshot-sync') */
     const char *new_image_file;
     ExternalSnapshotState *state =
                              DO_UPCAST(ExternalSnapshotState, common, common);
     TransactionAction *action = common->action;
     AioContext *aio_context;
     uint64_t perm, shared;
 
     /* 'blockdev-snapshot' and 'blockdev-snapshot-sync' have similar
      * purpose but a different set of parameters */
     switch (action->type) {
     case TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT:
         {
             BlockdevSnapshot *s = action->u.blockdev_snapshot.data;
             device = s->node;
             node_name = s->node;
             new_image_file = NULL;
             snapshot_ref = s->overlay;
         }
         break;
     case TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC:
         {
             BlockdevSnapshotSync *s = action->u.blockdev_snapshot_sync.data;
             device = s->has_device ? s->device : NULL;
             node_name = s->has_node_name ? s->node_name : NULL;
             new_image_file = s->snapshot_file;
             snapshot_ref = NULL;
         }
         break;
     default:
         g_assert_not_reached();
     }
 
     /* start processing */
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     state->old_bs = bdrv_lookup_bs(device, node_name, errp);
     if (!state->old_bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(state->old_bs);
     aio_context_acquire(aio_context);
 
     /* Paired with .clean() */
     bdrv_drained_begin(state->old_bs);
 
     if (!bdrv_is_inserted(state->old_bs)) {
         error_setg(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
         goto out;
     }
 
     if (bdrv_op_is_blocked(state->old_bs,
                            BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT, errp)) {
         goto out;
     }
 
     if (!bdrv_is_read_only(state->old_bs)) {
         if (bdrv_flush(state->old_bs)) {
             error_setg(errp, QERR_IO_ERROR);
             goto out;
         }
     }
 
     if (action->type == TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC) {
         BlockdevSnapshotSync *s = action->u.blockdev_snapshot_sync.data;
         const char *format = s->has_format ? s->format : "qcow2";
         enum NewImageMode mode;
         const char *snapshot_node_name =
             s->has_snapshot_node_name ? s->snapshot_node_name : NULL;
 
         if (node_name && !snapshot_node_name) {
             error_setg(errp, "New overlay node-name missing");
             goto out;
         }
 
         if (snapshot_node_name &&
             bdrv_lookup_bs(snapshot_node_name, snapshot_node_name, NULL)) {
             error_setg(errp, "New overlay node-name already in use");
             goto out;
         }
 
         flags = state->old_bs->open_flags;
         flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_COPY_ON_READ);
         flags |= BDRV_O_NO_BACKING;
 
         /* create new image w/backing file */
         mode = s->has_mode ? s->mode : NEW_IMAGE_MODE_ABSOLUTE_PATHS;
         if (mode != NEW_IMAGE_MODE_EXISTING) {
             int64_t size = bdrv_getlength(state->old_bs);
             if (size < 0) {
                 error_setg_errno(errp, -size, "bdrv_getlength failed");
                 goto out;
             }
             bdrv_refresh_filename(state->old_bs);
             bdrv_img_create(new_image_file, format,
                             state->old_bs->filename,
                             state->old_bs->drv->format_name,
                             NULL, size, flags, false, &local_err);
             if (local_err) {
                 error_propagate(errp, local_err);
                 goto out;
             }
         }
 
         options = qdict_new();
         if (snapshot_node_name) {
             qdict_put_str(options, "node-name", snapshot_node_name);
         }
         qdict_put_str(options, "driver", format);
     }
 
     state->new_bs = bdrv_open(new_image_file, snapshot_ref, options, flags,
                               errp);
     /* We will manually add the backing_hd field to the bs later */
     if (!state->new_bs) {
         goto out;
     }
 
     /*
      * Allow attaching a backing file to an overlay that's already in use only
      * if the parents don't assume that they are already seeing a valid image.
      * (Specifically, allow it as a mirror target, which is write-only access.)
      */
     bdrv_get_cumulative_perm(state->new_bs, &perm, &shared);
     if (perm & BLK_PERM_CONSISTENT_READ) {
         error_setg(errp, "The overlay is already in use");
         goto out;
     }
 
     if (state->new_bs->drv->is_filter) {
         error_setg(errp, "Filters cannot be used as overlays");
         goto out;
     }
 
     if (bdrv_cow_child(state->new_bs)) {
         error_setg(errp, "The overlay already has a backing image");
         goto out;
     }
 
     if (!state->new_bs->drv->supports_backing) {
         error_setg(errp, "The overlay does not support backing images");
         goto out;
     }
 
     ret = bdrv_append(state->new_bs, state->old_bs, errp);
     if (ret < 0) {
         goto out;
     }
     state->overlay_appended = true;
 
 out:
     aio_context_release(aio_context);
 }
 
 static void external_snapshot_commit(BlkActionState *common)
 {
     ExternalSnapshotState *state =
                              DO_UPCAST(ExternalSnapshotState, common, common);
     AioContext *aio_context;
 
     aio_context = bdrv_get_aio_context(state->old_bs);
     aio_context_acquire(aio_context);
 
     /* We don't need (or want) to use the transactional
      * bdrv_reopen_multiple() across all the entries at once, because we
      * don't want to abort all of them if one of them fails the reopen */
     if (!qatomic_read(&state->old_bs->copy_on_read)) {
         bdrv_reopen_set_read_only(state->old_bs, true, NULL);
     }
 
     aio_context_release(aio_context);
 }
 
 static void external_snapshot_abort(BlkActionState *common)
 {
     ExternalSnapshotState *state =
                              DO_UPCAST(ExternalSnapshotState, common, common);
     if (state->new_bs) {
         if (state->overlay_appended) {
             AioContext *aio_context;
             AioContext *tmp_context;
             int ret;
 
             aio_context = bdrv_get_aio_context(state->old_bs);
             aio_context_acquire(aio_context);
 
             bdrv_ref(state->old_bs);   /* we can't let bdrv_set_backind_hd()
                                           close state->old_bs; we need it */
             bdrv_set_backing_hd(state->new_bs, NULL, &error_abort);
 
             /*
              * The call to bdrv_set_backing_hd() above returns state->old_bs to
              * the main AioContext. As we're still going to be using it, return
              * it to the AioContext it was before.
              */
             tmp_context = bdrv_get_aio_context(state->old_bs);
             if (aio_context != tmp_context) {
                 aio_context_release(aio_context);
                 aio_context_acquire(tmp_context);
 
                 ret = bdrv_try_change_aio_context(state->old_bs,
                                                   aio_context, NULL, NULL);
                 assert(ret == 0);
 
                 aio_context_release(tmp_context);
                 aio_context_acquire(aio_context);
             }
 
             bdrv_replace_node(state->new_bs, state->old_bs, &error_abort);
             bdrv_unref(state->old_bs); /* bdrv_replace_node() ref'ed old_bs */
 
             aio_context_release(aio_context);
         }
     }
 }
 
 static void external_snapshot_clean(BlkActionState *common)
 {
     ExternalSnapshotState *state =
                              DO_UPCAST(ExternalSnapshotState, common, common);
     AioContext *aio_context;
 
     if (!state->old_bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(state->old_bs);
     aio_context_acquire(aio_context);
 
     bdrv_drained_end(state->old_bs);
     bdrv_unref(state->new_bs);
 
     aio_context_release(aio_context);
 }
 
 typedef struct DriveBackupState {
     BlkActionState common;
     BlockDriverState *bs;
     BlockJob *job;
 } DriveBackupState;
 
 static BlockJob *do_backup_common(BackupCommon *backup,
                                   BlockDriverState *bs,
                                   BlockDriverState *target_bs,
                                   AioContext *aio_context,
                                   JobTxn *txn, Error **errp);
 
 static void drive_backup_prepare(BlkActionState *common, Error **errp)
 {
     DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
     DriveBackup *backup;
     BlockDriverState *bs;
     BlockDriverState *target_bs;
     BlockDriverState *source = NULL;
     AioContext *aio_context;
     AioContext *old_context;
     QDict *options;
     Error *local_err = NULL;
     int flags;
     int64_t size;
     bool set_backing_hd = false;
     int ret;
 
     assert(common->action->type == TRANSACTION_ACTION_KIND_DRIVE_BACKUP);
     backup = common->action->u.drive_backup.data;
 
     if (!backup->has_mode) {
         backup->mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
     }
 
     bs = bdrv_lookup_bs(backup->device, backup->device, errp);
     if (!bs) {
         return;
     }
 
     if (!bs->drv) {
         error_setg(errp, "Device has no medium");
         return;
     }
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     state->bs = bs;
     /* Paired with .clean() */
     bdrv_drained_begin(bs);
 
     if (!backup->has_format) {
         backup->format = backup->mode == NEW_IMAGE_MODE_EXISTING ?
                          NULL : (char *) bs->drv->format_name;
     }
 
     /* Early check to avoid creating target */
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
         goto out;
     }
 
     flags = bs->open_flags | BDRV_O_RDWR;
 
     /*
      * See if we have a backing HD we can use to create our new image
      * on top of.
      */
     if (backup->sync == MIRROR_SYNC_MODE_TOP) {
         /*
          * Backup will not replace the source by the target, so none
          * of the filters skipped here will be removed (in contrast to
          * mirror).  Therefore, we can skip all of them when looking
          * for the first COW relationship.
          */
         source = bdrv_cow_bs(bdrv_skip_filters(bs));
         if (!source) {
             backup->sync = MIRROR_SYNC_MODE_FULL;
         }
     }
     if (backup->sync == MIRROR_SYNC_MODE_NONE) {
         source = bs;
         flags |= BDRV_O_NO_BACKING;
         set_backing_hd = true;
     }
 
     size = bdrv_getlength(bs);
     if (size < 0) {
         error_setg_errno(errp, -size, "bdrv_getlength failed");
         goto out;
     }
 
     if (backup->mode != NEW_IMAGE_MODE_EXISTING) {
         assert(backup->format);
         if (source) {
             /* Implicit filters should not appear in the filename */
             BlockDriverState *explicit_backing =
                 bdrv_skip_implicit_filters(source);
 
             bdrv_refresh_filename(explicit_backing);
             bdrv_img_create(backup->target, backup->format,
                             explicit_backing->filename,
                             explicit_backing->drv->format_name, NULL,
                             size, flags, false, &local_err);
         } else {
             bdrv_img_create(backup->target, backup->format, NULL, NULL, NULL,
                             size, flags, false, &local_err);
         }
     }
 
     if (local_err) {
         error_propagate(errp, local_err);
         goto out;
     }
 
     options = qdict_new();
     qdict_put_str(options, "discard", "unmap");
     qdict_put_str(options, "detect-zeroes", "unmap");
     if (backup->format) {
         qdict_put_str(options, "driver", backup->format);
     }
 
     target_bs = bdrv_open(backup->target, NULL, options, flags, errp);
     if (!target_bs) {
         goto out;
     }
 
     /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     old_context = bdrv_get_aio_context(target_bs);
     aio_context_release(aio_context);
     aio_context_acquire(old_context);
 
     ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
     if (ret < 0) {
         bdrv_unref(target_bs);
         aio_context_release(old_context);
         return;
     }
 
     aio_context_release(old_context);
     aio_context_acquire(aio_context);
 
     if (set_backing_hd) {
         if (bdrv_set_backing_hd(target_bs, source, errp) < 0) {
             goto unref;
         }
     }
 
     state->job = do_backup_common(qapi_DriveBackup_base(backup),
                                   bs, target_bs, aio_context,
                                   common->block_job_txn, errp);
 
 unref:
     bdrv_unref(target_bs);
 out:
     aio_context_release(aio_context);
 }
 
 static void drive_backup_commit(BlkActionState *common)
 {
     DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
     AioContext *aio_context;
 
     aio_context = bdrv_get_aio_context(state->bs);
     aio_context_acquire(aio_context);
 
     assert(state->job);
     job_start(&state->job->job);
 
     aio_context_release(aio_context);
 }
 
 static void drive_backup_abort(BlkActionState *common)
 {
     DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
 
     if (state->job) {
         job_cancel_sync(&state->job->job, true);
     }
 }
 
 static void drive_backup_clean(BlkActionState *common)
 {
     DriveBackupState *state = DO_UPCAST(DriveBackupState, common, common);
     AioContext *aio_context;
 
     if (!state->bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(state->bs);
     aio_context_acquire(aio_context);
 
     bdrv_drained_end(state->bs);
 
     aio_context_release(aio_context);
 }
 
 typedef struct BlockdevBackupState {
     BlkActionState common;
     BlockDriverState *bs;
     BlockJob *job;
 } BlockdevBackupState;
 
 static void blockdev_backup_prepare(BlkActionState *common, Error **errp)
 {
     BlockdevBackupState *state = DO_UPCAST(BlockdevBackupState, common, common);
     BlockdevBackup *backup;
     BlockDriverState *bs;
     BlockDriverState *target_bs;
     AioContext *aio_context;
     AioContext *old_context;
     int ret;
 
     assert(common->action->type == TRANSACTION_ACTION_KIND_BLOCKDEV_BACKUP);
     backup = common->action->u.blockdev_backup.data;
 
     bs = bdrv_lookup_bs(backup->device, backup->device, errp);
     if (!bs) {
         return;
     }
 
     target_bs = bdrv_lookup_bs(backup->target, backup->target, errp);
     if (!target_bs) {
         return;
     }
 
     /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     aio_context = bdrv_get_aio_context(bs);
     old_context = bdrv_get_aio_context(target_bs);
     aio_context_acquire(old_context);
 
     ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
     if (ret < 0) {
         aio_context_release(old_context);
         return;
     }
 
     aio_context_release(old_context);
     aio_context_acquire(aio_context);
     state->bs = bs;
 
     /* Paired with .clean() */
     bdrv_drained_begin(state->bs);
 
     state->job = do_backup_common(qapi_BlockdevBackup_base(backup),
                                   bs, target_bs, aio_context,
                                   common->block_job_txn, errp);
 
     aio_context_release(aio_context);
 }
 
 static void blockdev_backup_commit(BlkActionState *common)
 {
     BlockdevBackupState *state = DO_UPCAST(BlockdevBackupState, common, common);
     AioContext *aio_context;
 
     aio_context = bdrv_get_aio_context(state->bs);
     aio_context_acquire(aio_context);
 
     assert(state->job);
     job_start(&state->job->job);
 
     aio_context_release(aio_context);
 }
 
 static void blockdev_backup_abort(BlkActionState *common)
 {
     BlockdevBackupState *state = DO_UPCAST(BlockdevBackupState, common, common);
 
     if (state->job) {
         job_cancel_sync(&state->job->job, true);
     }
 }
 
 static void blockdev_backup_clean(BlkActionState *common)
 {
     BlockdevBackupState *state = DO_UPCAST(BlockdevBackupState, common, common);
     AioContext *aio_context;
 
     if (!state->bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(state->bs);
     aio_context_acquire(aio_context);
 
     bdrv_drained_end(state->bs);
 
     aio_context_release(aio_context);
 }
 
 typedef struct BlockDirtyBitmapState {
     BlkActionState common;
     BdrvDirtyBitmap *bitmap;
     BlockDriverState *bs;
     HBitmap *backup;
     bool prepared;
     bool was_enabled;
 } BlockDirtyBitmapState;
 
 static void block_dirty_bitmap_add_prepare(BlkActionState *common,
                                            Error **errp)
 {
     Error *local_err = NULL;
     BlockDirtyBitmapAdd *action;
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     action = common->action->u.block_dirty_bitmap_add.data;
     /* AIO context taken and released within qmp_block_dirty_bitmap_add */
     qmp_block_dirty_bitmap_add(action->node, action->name,
                                action->has_granularity, action->granularity,
                                action->has_persistent, action->persistent,
                                action->has_disabled, action->disabled,
                                &local_err);
 
     if (!local_err) {
         state->prepared = true;
     } else {
         error_propagate(errp, local_err);
     }
 }
 
 static void block_dirty_bitmap_add_abort(BlkActionState *common)
 {
     BlockDirtyBitmapAdd *action;
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     action = common->action->u.block_dirty_bitmap_add.data;
     /* Should not be able to fail: IF the bitmap was added via .prepare(),
      * then the node reference and bitmap name must have been valid.
      */
     if (state->prepared) {
         qmp_block_dirty_bitmap_remove(action->node, action->name, &error_abort);
     }
 }
 
 static void block_dirty_bitmap_clear_prepare(BlkActionState *common,
                                              Error **errp)
 {
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
     BlockDirtyBitmap *action;
 
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     action = common->action->u.block_dirty_bitmap_clear.data;
     state->bitmap = block_dirty_bitmap_lookup(action->node,
                                               action->name,
                                               &state->bs,
                                               errp);
     if (!state->bitmap) {
         return;
     }
 
     if (bdrv_dirty_bitmap_check(state->bitmap, BDRV_BITMAP_DEFAULT, errp)) {
         return;
     }
 
     bdrv_clear_dirty_bitmap(state->bitmap, &state->backup);
 }
 
 static void block_dirty_bitmap_restore(BlkActionState *common)
 {
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (state->backup) {
         bdrv_restore_dirty_bitmap(state->bitmap, state->backup);
     }
 }
 
 static void block_dirty_bitmap_free_backup(BlkActionState *common)
 {
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     hbitmap_free(state->backup);
 }
 
 static void block_dirty_bitmap_enable_prepare(BlkActionState *common,
                                               Error **errp)
 {
     BlockDirtyBitmap *action;
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     action = common->action->u.block_dirty_bitmap_enable.data;
     state->bitmap = block_dirty_bitmap_lookup(action->node,
                                               action->name,
                                               NULL,
                                               errp);
     if (!state->bitmap) {
         return;
     }
 
     if (bdrv_dirty_bitmap_check(state->bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
         return;
     }
 
     state->was_enabled = bdrv_dirty_bitmap_enabled(state->bitmap);
     bdrv_enable_dirty_bitmap(state->bitmap);
 }
 
 static void block_dirty_bitmap_enable_abort(BlkActionState *common)
 {
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (!state->was_enabled) {
         bdrv_disable_dirty_bitmap(state->bitmap);
     }
 }
 
 static void block_dirty_bitmap_disable_prepare(BlkActionState *common,
                                                Error **errp)
 {
     BlockDirtyBitmap *action;
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     action = common->action->u.block_dirty_bitmap_disable.data;
     state->bitmap = block_dirty_bitmap_lookup(action->node,
                                               action->name,
                                               NULL,
                                               errp);
     if (!state->bitmap) {
         return;
     }
 
     if (bdrv_dirty_bitmap_check(state->bitmap, BDRV_BITMAP_ALLOW_RO, errp)) {
         return;
     }
 
     state->was_enabled = bdrv_dirty_bitmap_enabled(state->bitmap);
     bdrv_disable_dirty_bitmap(state->bitmap);
 }
 
 static void block_dirty_bitmap_disable_abort(BlkActionState *common)
 {
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (state->was_enabled) {
         bdrv_enable_dirty_bitmap(state->bitmap);
     }
 }
 
 static void block_dirty_bitmap_merge_prepare(BlkActionState *common,
                                              Error **errp)
 {
     BlockDirtyBitmapMerge *action;
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     action = common->action->u.block_dirty_bitmap_merge.data;
 
     state->bitmap = block_dirty_bitmap_merge(action->node, action->target,
                                              action->bitmaps, &state->backup,
                                              errp);
 }
 
 static void block_dirty_bitmap_remove_prepare(BlkActionState *common,
                                               Error **errp)
 {
     BlockDirtyBitmap *action;
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (action_check_completion_mode(common, errp) < 0) {
         return;
     }
 
     action = common->action->u.block_dirty_bitmap_remove.data;
 
     state->bitmap = block_dirty_bitmap_remove(action->node, action->name,
                                               false, &state->bs, errp);
     if (state->bitmap) {
         bdrv_dirty_bitmap_skip_store(state->bitmap, true);
         bdrv_dirty_bitmap_set_busy(state->bitmap, true);
     }
 }
 
 static void block_dirty_bitmap_remove_abort(BlkActionState *common)
 {
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     if (state->bitmap) {
         bdrv_dirty_bitmap_skip_store(state->bitmap, false);
         bdrv_dirty_bitmap_set_busy(state->bitmap, false);
     }
 }
 
 static void block_dirty_bitmap_remove_commit(BlkActionState *common)
 {
     BlockDirtyBitmapState *state = DO_UPCAST(BlockDirtyBitmapState,
                                              common, common);
 
     bdrv_dirty_bitmap_set_busy(state->bitmap, false);
     bdrv_release_dirty_bitmap(state->bitmap);
 }
 
 static void abort_prepare(BlkActionState *common, Error **errp)
 {
     error_setg(errp, "Transaction aborted using Abort action");
 }
 
 static void abort_commit(BlkActionState *common)
 {
     g_assert_not_reached(); /* this action never succeeds */
 }
 
 static const BlkActionOps actions[] = {
     [TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT] = {
         .instance_size = sizeof(ExternalSnapshotState),
         .prepare  = external_snapshot_prepare,
         .commit   = external_snapshot_commit,
         .abort = external_snapshot_abort,
         .clean = external_snapshot_clean,
     },
     [TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_SYNC] = {
         .instance_size = sizeof(ExternalSnapshotState),
         .prepare  = external_snapshot_prepare,
         .commit   = external_snapshot_commit,
         .abort = external_snapshot_abort,
         .clean = external_snapshot_clean,
     },
     [TRANSACTION_ACTION_KIND_DRIVE_BACKUP] = {
         .instance_size = sizeof(DriveBackupState),
         .prepare = drive_backup_prepare,
         .commit = drive_backup_commit,
         .abort = drive_backup_abort,
         .clean = drive_backup_clean,
     },
     [TRANSACTION_ACTION_KIND_BLOCKDEV_BACKUP] = {
         .instance_size = sizeof(BlockdevBackupState),
         .prepare = blockdev_backup_prepare,
         .commit = blockdev_backup_commit,
         .abort = blockdev_backup_abort,
         .clean = blockdev_backup_clean,
     },
     [TRANSACTION_ACTION_KIND_ABORT] = {
         .instance_size = sizeof(BlkActionState),
         .prepare = abort_prepare,
         .commit = abort_commit,
     },
     [TRANSACTION_ACTION_KIND_BLOCKDEV_SNAPSHOT_INTERNAL_SYNC] = {
         .instance_size = sizeof(InternalSnapshotState),
         .prepare  = internal_snapshot_prepare,
         .abort = internal_snapshot_abort,
         .clean = internal_snapshot_clean,
     },
     [TRANSACTION_ACTION_KIND_BLOCK_DIRTY_BITMAP_ADD] = {
         .instance_size = sizeof(BlockDirtyBitmapState),
         .prepare = block_dirty_bitmap_add_prepare,
         .abort = block_dirty_bitmap_add_abort,
     },
     [TRANSACTION_ACTION_KIND_BLOCK_DIRTY_BITMAP_CLEAR] = {
         .instance_size = sizeof(BlockDirtyBitmapState),
         .prepare = block_dirty_bitmap_clear_prepare,
         .commit = block_dirty_bitmap_free_backup,
         .abort = block_dirty_bitmap_restore,
     },
     [TRANSACTION_ACTION_KIND_BLOCK_DIRTY_BITMAP_ENABLE] = {
         .instance_size = sizeof(BlockDirtyBitmapState),
         .prepare = block_dirty_bitmap_enable_prepare,
         .abort = block_dirty_bitmap_enable_abort,
     },
     [TRANSACTION_ACTION_KIND_BLOCK_DIRTY_BITMAP_DISABLE] = {
         .instance_size = sizeof(BlockDirtyBitmapState),
         .prepare = block_dirty_bitmap_disable_prepare,
         .abort = block_dirty_bitmap_disable_abort,
     },
     [TRANSACTION_ACTION_KIND_BLOCK_DIRTY_BITMAP_MERGE] = {
         .instance_size = sizeof(BlockDirtyBitmapState),
         .prepare = block_dirty_bitmap_merge_prepare,
         .commit = block_dirty_bitmap_free_backup,
         .abort = block_dirty_bitmap_restore,
     },
     [TRANSACTION_ACTION_KIND_BLOCK_DIRTY_BITMAP_REMOVE] = {
         .instance_size = sizeof(BlockDirtyBitmapState),
         .prepare = block_dirty_bitmap_remove_prepare,
         .commit = block_dirty_bitmap_remove_commit,
         .abort = block_dirty_bitmap_remove_abort,
     },
     /* Where are transactions for MIRROR, COMMIT and STREAM?
      * Although these blockjobs use transaction callbacks like the backup job,
      * these jobs do not necessarily adhere to transaction semantics.
      * These jobs may not fully undo all of their actions on abort, nor do they
      * necessarily work in transactions with more than one job in them.
      */
 };
 
 /**
  * Allocate a TransactionProperties structure if necessary, and fill
  * that structure with desired defaults if they are unset.
  */
 static TransactionProperties *get_transaction_properties(
     TransactionProperties *props)
 {
     if (!props) {
         props = g_new0(TransactionProperties, 1);
     }
 
     if (!props->has_completion_mode) {
         props->has_completion_mode = true;
         props->completion_mode = ACTION_COMPLETION_MODE_INDIVIDUAL;
     }
 
     return props;
 }
 
 /*
  * 'Atomic' group operations.  The operations are performed as a set, and if
  * any fail then we roll back all operations in the group.
  *
  * Always run under BQL.
  */
 void qmp_transaction(TransactionActionList *dev_list,
                      bool has_props,
                      struct TransactionProperties *props,
                      Error **errp)
 {
     TransactionActionList *dev_entry = dev_list;
     JobTxn *block_job_txn = NULL;
     BlkActionState *state, *next;
     Error *local_err = NULL;
 
     GLOBAL_STATE_CODE();
 
     QTAILQ_HEAD(, BlkActionState) snap_bdrv_states;
     QTAILQ_INIT(&snap_bdrv_states);
 
     /* Does this transaction get canceled as a group on failure?
      * If not, we don't really need to make a JobTxn.
      */
     props = get_transaction_properties(props);
     if (props->completion_mode != ACTION_COMPLETION_MODE_INDIVIDUAL) {
         block_job_txn = job_txn_new();
     }
 
     /* drain all i/o before any operations */
     bdrv_drain_all();
 
     /* We don't do anything in this loop that commits us to the operations */
     while (NULL != dev_entry) {
         TransactionAction *dev_info = NULL;
         const BlkActionOps *ops;
 
         dev_info = dev_entry->value;
         dev_entry = dev_entry->next;
 
         assert(dev_info->type < ARRAY_SIZE(actions));
 
         ops = &actions[dev_info->type];
         assert(ops->instance_size > 0);
 
         state = g_malloc0(ops->instance_size);
         state->ops = ops;
         state->action = dev_info;
         state->block_job_txn = block_job_txn;
         state->txn_props = props;
         QTAILQ_INSERT_TAIL(&snap_bdrv_states, state, entry);
 
         state->ops->prepare(state, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
             goto delete_and_fail;
         }
     }
 
     QTAILQ_FOREACH(state, &snap_bdrv_states, entry) {
         if (state->ops->commit) {
             state->ops->commit(state);
         }
     }
 
     /* success */
     goto exit;
 
 delete_and_fail:
     /* failure, and it is all-or-none; roll back all operations */
     QTAILQ_FOREACH_REVERSE(state, &snap_bdrv_states, entry) {
         if (state->ops->abort) {
             state->ops->abort(state);
         }
     }
 exit:
     QTAILQ_FOREACH_SAFE(state, &snap_bdrv_states, entry, next) {
         if (state->ops->clean) {
             state->ops->clean(state);
         }
         g_free(state);
     }
     if (!has_props) {
         qapi_free_TransactionProperties(props);
     }
     job_txn_unref(block_job_txn);
 }
 
 BlockDirtyBitmapSha256 *qmp_x_debug_block_dirty_bitmap_sha256(const char *node,
                                                               const char *name,
                                                               Error **errp)
 {
     BdrvDirtyBitmap *bitmap;
     BlockDriverState *bs;
     BlockDirtyBitmapSha256 *ret = NULL;
     char *sha256;
 
     bitmap = block_dirty_bitmap_lookup(node, name, &bs, errp);
     if (!bitmap || !bs) {
         return NULL;
     }
 
     sha256 = bdrv_dirty_bitmap_sha256(bitmap, errp);
     if (sha256 == NULL) {
         return NULL;
     }
 
     ret = g_new(BlockDirtyBitmapSha256, 1);
     ret->sha256 = sha256;
 
     return ret;
 }
 
 void coroutine_fn qmp_block_resize(bool has_device, const char *device,
                                    bool has_node_name, const char *node_name,
                                    int64_t size, Error **errp)
 {
     Error *local_err = NULL;
     BlockBackend *blk;
     BlockDriverState *bs;
     AioContext *old_ctx;
 
     bs = bdrv_lookup_bs(has_device ? device : NULL,
                         has_node_name ? node_name : NULL,
                         &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
     }
 
     if (size < 0) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "size", "a >0 size");
         return;
     }
 
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_RESIZE, NULL)) {
         error_setg(errp, QERR_DEVICE_IN_USE, device);
         return;
     }
 
     blk = blk_new_with_bs(bs, BLK_PERM_RESIZE, BLK_PERM_ALL, errp);
     if (!blk) {
         return;
     }
 
     bdrv_co_lock(bs);
     bdrv_drained_begin(bs);
     bdrv_co_unlock(bs);
 
     old_ctx = bdrv_co_enter(bs);
     blk_co_truncate(blk, size, false, PREALLOC_MODE_OFF, 0, errp);
     bdrv_co_leave(bs, old_ctx);
 
     bdrv_co_lock(bs);
     bdrv_drained_end(bs);
     blk_unref(blk);
     bdrv_co_unlock(bs);
 }
 
 void qmp_block_stream(bool has_job_id, const char *job_id, const char *device,
                       bool has_base, const char *base,
                       bool has_base_node, const char *base_node,
                       bool has_backing_file, const char *backing_file,
                       bool has_bottom, const char *bottom,
                       bool has_speed, int64_t speed,
                       bool has_on_error, BlockdevOnError on_error,
                       bool has_filter_node_name, const char *filter_node_name,
                       bool has_auto_finalize, bool auto_finalize,
                       bool has_auto_dismiss, bool auto_dismiss,
                       Error **errp)
 {
     BlockDriverState *bs, *iter, *iter_end;
     BlockDriverState *base_bs = NULL;
     BlockDriverState *bottom_bs = NULL;
     AioContext *aio_context;
     Error *local_err = NULL;
     int job_flags = JOB_DEFAULT;
 
     if (has_base && has_base_node) {
         error_setg(errp, "'base' and 'base-node' cannot be specified "
                    "at the same time");
         return;
     }
 
     if (has_base && has_bottom) {
         error_setg(errp, "'base' and 'bottom' cannot be specified "
                    "at the same time");
         return;
     }
 
     if (has_bottom && has_base_node) {
         error_setg(errp, "'bottom' and 'base-node' cannot be specified "
                    "at the same time");
         return;
     }
 
     if (!has_on_error) {
         on_error = BLOCKDEV_ON_ERROR_REPORT;
     }
 
     bs = bdrv_lookup_bs(device, device, errp);
     if (!bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     if (has_base) {
         base_bs = bdrv_find_backing_image(bs, base);
         if (base_bs == NULL) {
             error_setg(errp, "Can't find '%s' in the backing chain", base);
             goto out;
         }
         assert(bdrv_get_aio_context(base_bs) == aio_context);
     }
 
     if (has_base_node) {
         base_bs = bdrv_lookup_bs(NULL, base_node, errp);
         if (!base_bs) {
             goto out;
         }
         if (bs == base_bs || !bdrv_chain_contains(bs, base_bs)) {
             error_setg(errp, "Node '%s' is not a backing image of '%s'",
                        base_node, device);
             goto out;
         }
         assert(bdrv_get_aio_context(base_bs) == aio_context);
         bdrv_refresh_filename(base_bs);
     }
 
     if (has_bottom) {
         bottom_bs = bdrv_lookup_bs(NULL, bottom, errp);
         if (!bottom_bs) {
             goto out;
         }
         if (!bottom_bs->drv) {
             error_setg(errp, "Node '%s' is not open", bottom);
             goto out;
         }
         if (bottom_bs->drv->is_filter) {
             error_setg(errp, "Node '%s' is a filter, use a non-filter node "
                        "as 'bottom'", bottom);
             goto out;
         }
         if (!bdrv_chain_contains(bs, bottom_bs)) {
             error_setg(errp, "Node '%s' is not in a chain starting from '%s'",
                        bottom, device);
             goto out;
         }
         assert(bdrv_get_aio_context(bottom_bs) == aio_context);
     }
 
     /*
      * Check for op blockers in the whole chain between bs and base (or bottom)
      */
     iter_end = has_bottom ? bdrv_filter_or_cow_bs(bottom_bs) : base_bs;
     for (iter = bs; iter && iter != iter_end;
          iter = bdrv_filter_or_cow_bs(iter))
     {
         if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_STREAM, errp)) {
             goto out;
         }
     }
 
     /* if we are streaming the entire chain, the result will have no backing
      * file, and specifying one is therefore an error */
     if (base_bs == NULL && has_backing_file) {
         error_setg(errp, "backing file specified, but streaming the "
                          "entire chain");
         goto out;
     }
 
     if (has_auto_finalize && !auto_finalize) {
         job_flags |= JOB_MANUAL_FINALIZE;
     }
     if (has_auto_dismiss && !auto_dismiss) {
         job_flags |= JOB_MANUAL_DISMISS;
     }
 
     stream_start(has_job_id ? job_id : NULL, bs, base_bs, backing_file,
                  bottom_bs, job_flags, has_speed ? speed : 0, on_error,
                  filter_node_name, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto out;
     }
 
     trace_qmp_block_stream(bs);
 
 out:
     aio_context_release(aio_context);
 }
 
 void qmp_block_commit(bool has_job_id, const char *job_id, const char *device,
                       bool has_base_node, const char *base_node,
                       bool has_base, const char *base,
                       bool has_top_node, const char *top_node,
                       bool has_top, const char *top,
                       bool has_backing_file, const char *backing_file,
                       bool has_speed, int64_t speed,
                       bool has_on_error, BlockdevOnError on_error,
                       bool has_filter_node_name, const char *filter_node_name,
                       bool has_auto_finalize, bool auto_finalize,
                       bool has_auto_dismiss, bool auto_dismiss,
                       Error **errp)
 {
     BlockDriverState *bs;
     BlockDriverState *iter;
     BlockDriverState *base_bs, *top_bs;
     AioContext *aio_context;
     Error *local_err = NULL;
     int job_flags = JOB_DEFAULT;
     uint64_t top_perm, top_shared;
 
     if (!has_speed) {
         speed = 0;
     }
     if (!has_on_error) {
         on_error = BLOCKDEV_ON_ERROR_REPORT;
     }
     if (!has_filter_node_name) {
         filter_node_name = NULL;
     }
     if (has_auto_finalize && !auto_finalize) {
         job_flags |= JOB_MANUAL_FINALIZE;
     }
     if (has_auto_dismiss && !auto_dismiss) {
         job_flags |= JOB_MANUAL_DISMISS;
     }
 
     /* Important Note:
      *  libvirt relies on the DeviceNotFound error class in order to probe for
      *  live commit feature versions; for this to work, we must make sure to
      *  perform the device lookup before any generic errors that may occur in a
      *  scenario in which all optional arguments are omitted. */
     bs = qmp_get_root_bs(device, &local_err);
     if (!bs) {
         bs = bdrv_lookup_bs(device, device, NULL);
         if (!bs) {
             error_free(local_err);
             error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
                       "Device '%s' not found", device);
         } else {
             error_propagate(errp, local_err);
         }
         return;
     }
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, errp)) {
         goto out;
     }
 
     /* default top_bs is the active layer */
     top_bs = bs;
 
     if (has_top_node && has_top) {
         error_setg(errp, "'top-node' and 'top' are mutually exclusive");
         goto out;
     } else if (has_top_node) {
         top_bs = bdrv_lookup_bs(NULL, top_node, errp);
         if (top_bs == NULL) {
             goto out;
         }
         if (!bdrv_chain_contains(bs, top_bs)) {
             error_setg(errp, "'%s' is not in this backing file chain",
                        top_node);
             goto out;
         }
     } else if (has_top && top) {
         /* This strcmp() is just a shortcut, there is no need to
          * refresh @bs's filename.  If it mismatches,
          * bdrv_find_backing_image() will do the refresh and may still
          * return @bs. */
         if (strcmp(bs->filename, top) != 0) {
             top_bs = bdrv_find_backing_image(bs, top);
         }
     }
 
     if (top_bs == NULL) {
         error_setg(errp, "Top image file %s not found", top ? top : "NULL");
         goto out;
     }
 
     assert(bdrv_get_aio_context(top_bs) == aio_context);
 
     if (has_base_node && has_base) {
         error_setg(errp, "'base-node' and 'base' are mutually exclusive");
         goto out;
     } else if (has_base_node) {
         base_bs = bdrv_lookup_bs(NULL, base_node, errp);
         if (base_bs == NULL) {
             goto out;
         }
         if (!bdrv_chain_contains(top_bs, base_bs)) {
             error_setg(errp, "'%s' is not in this backing file chain",
                        base_node);
             goto out;
         }
     } else if (has_base && base) {
         base_bs = bdrv_find_backing_image(top_bs, base);
         if (base_bs == NULL) {
             error_setg(errp, "Can't find '%s' in the backing chain", base);
             goto out;
         }
     } else {
         base_bs = bdrv_find_base(top_bs);
         if (base_bs == NULL) {
             error_setg(errp, "There is no backimg image");
             goto out;
         }
     }
 
     assert(bdrv_get_aio_context(base_bs) == aio_context);
 
     for (iter = top_bs; iter != bdrv_filter_or_cow_bs(base_bs);
          iter = bdrv_filter_or_cow_bs(iter))
     {
         if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_COMMIT_TARGET, errp)) {
             goto out;
         }
     }
 
     /* Do not allow attempts to commit an image into itself */
     if (top_bs == base_bs) {
         error_setg(errp, "cannot commit an image into itself");
         goto out;
     }
 
     /*
      * Active commit is required if and only if someone has taken a
      * WRITE permission on the top node.  Historically, we have always
      * used active commit for top nodes, so continue that practice
      * lest we possibly break clients that rely on this behavior, e.g.
      * to later attach this node to a writing parent.
      * (Active commit is never really wrong.)
      */
     bdrv_get_cumulative_perm(top_bs, &top_perm, &top_shared);
     if (top_perm & BLK_PERM_WRITE ||
         bdrv_skip_filters(top_bs) == bdrv_skip_filters(bs))
     {
         if (has_backing_file) {
             if (bdrv_skip_filters(top_bs) == bdrv_skip_filters(bs)) {
                 error_setg(errp, "'backing-file' specified,"
                                  " but 'top' is the active layer");
             } else {
                 error_setg(errp, "'backing-file' specified, but 'top' has a "
                                  "writer on it");
             }
             goto out;
         }
         if (!has_job_id) {
             /*
              * Emulate here what block_job_create() does, because it
              * is possible that @bs != @top_bs (the block job should
              * be named after @bs, even if @top_bs is the actual
              * source)
              */
             job_id = bdrv_get_device_name(bs);
         }
         commit_active_start(job_id, top_bs, base_bs, job_flags, speed, on_error,
                             filter_node_name, NULL, NULL, false, &local_err);
     } else {
         BlockDriverState *overlay_bs = bdrv_find_overlay(bs, top_bs);
         if (bdrv_op_is_blocked(overlay_bs, BLOCK_OP_TYPE_COMMIT_TARGET, errp)) {
             goto out;
         }
         commit_start(has_job_id ? job_id : NULL, bs, base_bs, top_bs, job_flags,
                      speed, on_error, has_backing_file ? backing_file : NULL,
                      filter_node_name, &local_err);
     }
     if (local_err != NULL) {
         error_propagate(errp, local_err);
         goto out;
     }
 
 out:
     aio_context_release(aio_context);
 }
 
 /* Common QMP interface for drive-backup and blockdev-backup */
 static BlockJob *do_backup_common(BackupCommon *backup,
                                   BlockDriverState *bs,
                                   BlockDriverState *target_bs,
                                   AioContext *aio_context,
                                   JobTxn *txn, Error **errp)
 {
     BlockJob *job = NULL;
     BdrvDirtyBitmap *bmap = NULL;
     BackupPerf perf = { .max_workers = 64 };
     int job_flags = JOB_DEFAULT;
 
     if (!backup->has_speed) {
         backup->speed = 0;
     }
     if (!backup->has_on_source_error) {
         backup->on_source_error = BLOCKDEV_ON_ERROR_REPORT;
     }
     if (!backup->has_on_target_error) {
         backup->on_target_error = BLOCKDEV_ON_ERROR_REPORT;
     }
     if (!backup->has_job_id) {
         backup->job_id = NULL;
     }
     if (!backup->has_auto_finalize) {
         backup->auto_finalize = true;
     }
     if (!backup->has_auto_dismiss) {
         backup->auto_dismiss = true;
     }
     if (!backup->has_compress) {
         backup->compress = false;
     }
 
     if (backup->x_perf) {
         if (backup->x_perf->has_use_copy_range) {
             perf.use_copy_range = backup->x_perf->use_copy_range;
         }
         if (backup->x_perf->has_max_workers) {
             perf.max_workers = backup->x_perf->max_workers;
         }
         if (backup->x_perf->has_max_chunk) {
             perf.max_chunk = backup->x_perf->max_chunk;
         }
     }
 
     if ((backup->sync == MIRROR_SYNC_MODE_BITMAP) ||
         (backup->sync == MIRROR_SYNC_MODE_INCREMENTAL)) {
         /* done before desugaring 'incremental' to print the right message */
         if (!backup->has_bitmap) {
             error_setg(errp, "must provide a valid bitmap name for "
                        "'%s' sync mode", MirrorSyncMode_str(backup->sync));
             return NULL;
         }
     }
 
     if (backup->sync == MIRROR_SYNC_MODE_INCREMENTAL) {
         if (backup->has_bitmap_mode &&
             backup->bitmap_mode != BITMAP_SYNC_MODE_ON_SUCCESS) {
             error_setg(errp, "Bitmap sync mode must be '%s' "
                        "when using sync mode '%s'",
                        BitmapSyncMode_str(BITMAP_SYNC_MODE_ON_SUCCESS),
                        MirrorSyncMode_str(backup->sync));
             return NULL;
         }
         backup->has_bitmap_mode = true;
         backup->sync = MIRROR_SYNC_MODE_BITMAP;
         backup->bitmap_mode = BITMAP_SYNC_MODE_ON_SUCCESS;
     }
 
     if (backup->has_bitmap) {
         bmap = bdrv_find_dirty_bitmap(bs, backup->bitmap);
         if (!bmap) {
             error_setg(errp, "Bitmap '%s' could not be found", backup->bitmap);
             return NULL;
         }
         if (!backup->has_bitmap_mode) {
             error_setg(errp, "Bitmap sync mode must be given "
                        "when providing a bitmap");
             return NULL;
         }
         if (bdrv_dirty_bitmap_check(bmap, BDRV_BITMAP_ALLOW_RO, errp)) {
             return NULL;
         }
 
         /* This does not produce a useful bitmap artifact: */
         if (backup->sync == MIRROR_SYNC_MODE_NONE) {
             error_setg(errp, "sync mode '%s' does not produce meaningful bitmap"
                        " outputs", MirrorSyncMode_str(backup->sync));
             return NULL;
         }
 
         /* If the bitmap isn't used for input or output, this is useless: */
         if (backup->bitmap_mode == BITMAP_SYNC_MODE_NEVER &&
             backup->sync != MIRROR_SYNC_MODE_BITMAP) {
             error_setg(errp, "Bitmap sync mode '%s' has no meaningful effect"
                        " when combined with sync mode '%s'",
                        BitmapSyncMode_str(backup->bitmap_mode),
                        MirrorSyncMode_str(backup->sync));
             return NULL;
         }
     }
 
     if (!backup->has_bitmap && backup->has_bitmap_mode) {
         error_setg(errp, "Cannot specify bitmap sync mode without a bitmap");
         return NULL;
     }
 
     if (!backup->auto_finalize) {
         job_flags |= JOB_MANUAL_FINALIZE;
     }
     if (!backup->auto_dismiss) {
         job_flags |= JOB_MANUAL_DISMISS;
     }
 
     job = backup_job_create(backup->job_id, bs, target_bs, backup->speed,
                             backup->sync, bmap, backup->bitmap_mode,
                             backup->compress,
                             backup->filter_node_name,
                             &perf,
                             backup->on_source_error,
                             backup->on_target_error,
                             job_flags, NULL, NULL, txn, errp);
     return job;
 }
 
 void qmp_drive_backup(DriveBackup *backup, Error **errp)
 {
     TransactionAction action = {
         .type = TRANSACTION_ACTION_KIND_DRIVE_BACKUP,
         .u.drive_backup.data = backup,
     };
     blockdev_do_action(&action, errp);
 }
 
 BlockDeviceInfoList *qmp_query_named_block_nodes(bool has_flat,
                                                  bool flat,
                                                  Error **errp)
 {
     bool return_flat = has_flat && flat;
 
     return bdrv_named_nodes_list(return_flat, errp);
 }
 
 XDbgBlockGraph *qmp_x_debug_query_block_graph(Error **errp)
 {
     return bdrv_get_xdbg_block_graph(errp);
 }
 
 void qmp_blockdev_backup(BlockdevBackup *backup, Error **errp)
 {
     TransactionAction action = {
         .type = TRANSACTION_ACTION_KIND_BLOCKDEV_BACKUP,
         .u.blockdev_backup.data = backup,
     };
     blockdev_do_action(&action, errp);
 }
 
 /* Parameter check and block job starting for drive mirroring.
  * Caller should hold @device and @target's aio context (must be the same).
  **/
 static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs,
                                    BlockDriverState *target,
                                    bool has_replaces, const char *replaces,
                                    enum MirrorSyncMode sync,
                                    BlockMirrorBackingMode backing_mode,
                                    bool zero_target,
                                    bool has_speed, int64_t speed,
                                    bool has_granularity, uint32_t granularity,
                                    bool has_buf_size, int64_t buf_size,
                                    bool has_on_source_error,
                                    BlockdevOnError on_source_error,
                                    bool has_on_target_error,
                                    BlockdevOnError on_target_error,
                                    bool has_unmap, bool unmap,
                                    bool has_filter_node_name,
                                    const char *filter_node_name,
                                    bool has_copy_mode, MirrorCopyMode copy_mode,
                                    bool has_auto_finalize, bool auto_finalize,
                                    bool has_auto_dismiss, bool auto_dismiss,
                                    Error **errp)
 {
     BlockDriverState *unfiltered_bs;
     int job_flags = JOB_DEFAULT;
 
     if (!has_speed) {
         speed = 0;
     }
     if (!has_on_source_error) {
         on_source_error = BLOCKDEV_ON_ERROR_REPORT;
     }
     if (!has_on_target_error) {
         on_target_error = BLOCKDEV_ON_ERROR_REPORT;
     }
     if (!has_granularity) {
         granularity = 0;
     }
     if (!has_buf_size) {
         buf_size = 0;
     }
     if (!has_unmap) {
         unmap = true;
     }
     if (!has_filter_node_name) {
         filter_node_name = NULL;
     }
     if (!has_copy_mode) {
         copy_mode = MIRROR_COPY_MODE_BACKGROUND;
     }
     if (has_auto_finalize && !auto_finalize) {
         job_flags |= JOB_MANUAL_FINALIZE;
     }
     if (has_auto_dismiss && !auto_dismiss) {
         job_flags |= JOB_MANUAL_DISMISS;
     }
 
     if (granularity != 0 && (granularity < 512 || granularity > 1048576 * 64)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "granularity",
                    "a value in range [512B, 64MB]");
         return;
     }
     if (granularity & (granularity - 1)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "granularity",
                    "a power of 2");
         return;
     }
 
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
         return;
     }
     if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_MIRROR_TARGET, errp)) {
         return;
     }
 
     if (!bdrv_backing_chain_next(bs) && sync == MIRROR_SYNC_MODE_TOP) {
         sync = MIRROR_SYNC_MODE_FULL;
     }
 
     if (!has_replaces) {
         /* We want to mirror from @bs, but keep implicit filters on top */
         unfiltered_bs = bdrv_skip_implicit_filters(bs);
         if (unfiltered_bs != bs) {
             replaces = unfiltered_bs->node_name;
             has_replaces = true;
         }
     }
 
     if (has_replaces) {
         BlockDriverState *to_replace_bs;
         AioContext *replace_aio_context;
         int64_t bs_size, replace_size;
 
         bs_size = bdrv_getlength(bs);
         if (bs_size < 0) {
             error_setg_errno(errp, -bs_size, "Failed to query device's size");
             return;
         }
 
         to_replace_bs = check_to_replace_node(bs, replaces, errp);
         if (!to_replace_bs) {
             return;
         }
 
         replace_aio_context = bdrv_get_aio_context(to_replace_bs);
         aio_context_acquire(replace_aio_context);
         replace_size = bdrv_getlength(to_replace_bs);
         aio_context_release(replace_aio_context);
 
         if (replace_size < 0) {
             error_setg_errno(errp, -replace_size,
                              "Failed to query the replacement node's size");
             return;
         }
         if (bs_size != replace_size) {
             error_setg(errp, "cannot replace image with a mirror image of "
                              "different size");
             return;
         }
     }
 
     /* pass the node name to replace to mirror start since it's loose coupling
      * and will allow to check whether the node still exist at mirror completion
      */
     mirror_start(job_id, bs, target,
                  has_replaces ? replaces : NULL, job_flags,
                  speed, granularity, buf_size, sync, backing_mode, zero_target,
                  on_source_error, on_target_error, unmap, filter_node_name,
                  copy_mode, errp);
 }
 
 void qmp_drive_mirror(DriveMirror *arg, Error **errp)
 {
     BlockDriverState *bs;
     BlockDriverState *target_backing_bs, *target_bs;
     AioContext *aio_context;
     AioContext *old_context;
     BlockMirrorBackingMode backing_mode;
     Error *local_err = NULL;
     QDict *options = NULL;
     int flags;
     int64_t size;
     const char *format = arg->format;
     bool zero_target;
     int ret;
 
     bs = qmp_get_root_bs(arg->device, errp);
     if (!bs) {
         return;
     }
 
     /* Early check to avoid creating target */
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_MIRROR_SOURCE, errp)) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     if (!arg->has_mode) {
         arg->mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
     }
 
     if (!arg->has_format) {
         format = (arg->mode == NEW_IMAGE_MODE_EXISTING
                   ? NULL : bs->drv->format_name);
     }
 
     flags = bs->open_flags | BDRV_O_RDWR;
     target_backing_bs = bdrv_cow_bs(bdrv_skip_filters(bs));
     if (!target_backing_bs && arg->sync == MIRROR_SYNC_MODE_TOP) {
         arg->sync = MIRROR_SYNC_MODE_FULL;
     }
     if (arg->sync == MIRROR_SYNC_MODE_NONE) {
         target_backing_bs = bs;
     }
 
     size = bdrv_getlength(bs);
     if (size < 0) {
         error_setg_errno(errp, -size, "bdrv_getlength failed");
         goto out;
     }
 
     if (arg->has_replaces) {
         if (!arg->has_node_name) {
             error_setg(errp, "a node-name must be provided when replacing a"
                              " named node of the graph");
             goto out;
         }
     }
 
     if (arg->mode == NEW_IMAGE_MODE_ABSOLUTE_PATHS) {
         backing_mode = MIRROR_SOURCE_BACKING_CHAIN;
     } else {
         backing_mode = MIRROR_OPEN_BACKING_CHAIN;
     }
 
     /* Don't open backing image in create() */
     flags |= BDRV_O_NO_BACKING;
 
     if ((arg->sync == MIRROR_SYNC_MODE_FULL || !target_backing_bs)
         && arg->mode != NEW_IMAGE_MODE_EXISTING)
     {
         /* create new image w/o backing file */
         assert(format);
         bdrv_img_create(arg->target, format,
                         NULL, NULL, NULL, size, flags, false, &local_err);
     } else {
         /* Implicit filters should not appear in the filename */
         BlockDriverState *explicit_backing =
             bdrv_skip_implicit_filters(target_backing_bs);
 
         switch (arg->mode) {
         case NEW_IMAGE_MODE_EXISTING:
             break;
         case NEW_IMAGE_MODE_ABSOLUTE_PATHS:
             /* create new image with backing file */
             bdrv_refresh_filename(explicit_backing);
             bdrv_img_create(arg->target, format,
                             explicit_backing->filename,
                             explicit_backing->drv->format_name,
                             NULL, size, flags, false, &local_err);
             break;
         default:
             abort();
         }
     }
 
     if (local_err) {
         error_propagate(errp, local_err);
         goto out;
     }
 
     options = qdict_new();
     if (arg->has_node_name) {
         qdict_put_str(options, "node-name", arg->node_name);
     }
     if (format) {
         qdict_put_str(options, "driver", format);
     }
 
     /* Mirroring takes care of copy-on-write using the source's backing
      * file.
      */
     target_bs = bdrv_open(arg->target, NULL, options, flags, errp);
     if (!target_bs) {
         goto out;
     }
 
     zero_target = (arg->sync == MIRROR_SYNC_MODE_FULL &&
                    (arg->mode == NEW_IMAGE_MODE_EXISTING ||
                     !bdrv_has_zero_init(target_bs)));
 
 
     /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     old_context = bdrv_get_aio_context(target_bs);
     aio_context_release(aio_context);
     aio_context_acquire(old_context);
 
     ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
     if (ret < 0) {
         bdrv_unref(target_bs);
         aio_context_release(old_context);
         return;
     }
 
     aio_context_release(old_context);
     aio_context_acquire(aio_context);
 
     blockdev_mirror_common(arg->has_job_id ? arg->job_id : NULL, bs, target_bs,
                            arg->has_replaces, arg->replaces, arg->sync,
                            backing_mode, zero_target,
                            arg->has_speed, arg->speed,
                            arg->has_granularity, arg->granularity,
                            arg->has_buf_size, arg->buf_size,
                            arg->has_on_source_error, arg->on_source_error,
                            arg->has_on_target_error, arg->on_target_error,
                            arg->has_unmap, arg->unmap,
                            false, NULL,
                            arg->has_copy_mode, arg->copy_mode,
                            arg->has_auto_finalize, arg->auto_finalize,
                            arg->has_auto_dismiss, arg->auto_dismiss,
                            errp);
     bdrv_unref(target_bs);
 out:
     aio_context_release(aio_context);
 }
 
 void qmp_blockdev_mirror(bool has_job_id, const char *job_id,
                          const char *device, const char *target,
                          bool has_replaces, const char *replaces,
                          MirrorSyncMode sync,
                          bool has_speed, int64_t speed,
                          bool has_granularity, uint32_t granularity,
                          bool has_buf_size, int64_t buf_size,
                          bool has_on_source_error,
                          BlockdevOnError on_source_error,
                          bool has_on_target_error,
                          BlockdevOnError on_target_error,
                          bool has_filter_node_name,
                          const char *filter_node_name,
                          bool has_copy_mode, MirrorCopyMode copy_mode,
                          bool has_auto_finalize, bool auto_finalize,
                          bool has_auto_dismiss, bool auto_dismiss,
                          Error **errp)
 {
     BlockDriverState *bs;
     BlockDriverState *target_bs;
     AioContext *aio_context;
     AioContext *old_context;
     BlockMirrorBackingMode backing_mode = MIRROR_LEAVE_BACKING_CHAIN;
     bool zero_target;
     int ret;
 
     bs = qmp_get_root_bs(device, errp);
     if (!bs) {
         return;
     }
 
     target_bs = bdrv_lookup_bs(target, target, errp);
     if (!target_bs) {
         return;
     }
 
     zero_target = (sync == MIRROR_SYNC_MODE_FULL);
 
     /* Honor bdrv_try_change_aio_context() context acquisition requirements. */
     old_context = bdrv_get_aio_context(target_bs);
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(old_context);
 
     ret = bdrv_try_change_aio_context(target_bs, aio_context, NULL, errp);
 
     aio_context_release(old_context);
     aio_context_acquire(aio_context);
 
     if (ret < 0) {
         goto out;
     }
 
     blockdev_mirror_common(has_job_id ? job_id : NULL, bs, target_bs,
                            has_replaces, replaces, sync, backing_mode,
                            zero_target, has_speed, speed,
                            has_granularity, granularity,
                            has_buf_size, buf_size,
                            has_on_source_error, on_source_error,
                            has_on_target_error, on_target_error,
                            true, true,
                            has_filter_node_name, filter_node_name,
                            has_copy_mode, copy_mode,
                            has_auto_finalize, auto_finalize,
                            has_auto_dismiss, auto_dismiss,
                            errp);
 out:
     aio_context_release(aio_context);
 }
 
 /*
  * Get a block job using its ID. Called with job_mutex held.
  */
 static BlockJob *find_block_job_locked(const char *id, Error **errp)
 {
     BlockJob *job;
 
     assert(id != NULL);
 
     job = block_job_get_locked(id);
 
     if (!job) {
         error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
                   "Block job '%s' not found", id);
         return NULL;
     }
 
     return job;
 }
 
 void qmp_block_job_set_speed(const char *device, int64_t speed, Error **errp)
 {
     BlockJob *job;
 
     JOB_LOCK_GUARD();
     job = find_block_job_locked(device, errp);
 
     if (!job) {
         return;
     }
 
     block_job_set_speed_locked(job, speed, errp);
 }
 
 void qmp_block_job_cancel(const char *device,
                           bool has_force, bool force, Error **errp)
 {
     BlockJob *job;
 
     JOB_LOCK_GUARD();
     job = find_block_job_locked(device, errp);
 
     if (!job) {
         return;
     }
 
     if (!has_force) {
         force = false;
     }
 
     if (job_user_paused_locked(&job->job) && !force) {
         error_setg(errp, "The block job for device '%s' is currently paused",
                    device);
         return;
     }
 
     trace_qmp_block_job_cancel(job);
     job_user_cancel_locked(&job->job, force, errp);
 }
 
 void qmp_block_job_pause(const char *device, Error **errp)
 {
     BlockJob *job;
 
     JOB_LOCK_GUARD();
     job = find_block_job_locked(device, errp);
 
     if (!job) {
         return;
     }
 
     trace_qmp_block_job_pause(job);
     job_user_pause_locked(&job->job, errp);
 }
 
 void qmp_block_job_resume(const char *device, Error **errp)
 {
     BlockJob *job;
 
     JOB_LOCK_GUARD();
     job = find_block_job_locked(device, errp);
 
     if (!job) {
         return;
     }
 
     trace_qmp_block_job_resume(job);
     job_user_resume_locked(&job->job, errp);
 }
 
 void qmp_block_job_complete(const char *device, Error **errp)
 {
     BlockJob *job;
 
     JOB_LOCK_GUARD();
     job = find_block_job_locked(device, errp);
 
     if (!job) {
         return;
     }
 
     trace_qmp_block_job_complete(job);
     job_complete_locked(&job->job, errp);
 }
 
 void qmp_block_job_finalize(const char *id, Error **errp)
 {
     BlockJob *job;
 
     JOB_LOCK_GUARD();
     job = find_block_job_locked(id, errp);
 
     if (!job) {
         return;
     }
 
     trace_qmp_block_job_finalize(job);
     job_ref_locked(&job->job);
     job_finalize_locked(&job->job, errp);
 
     job_unref_locked(&job->job);
 }
 
 void qmp_block_job_dismiss(const char *id, Error **errp)
 {
     BlockJob *bjob;
     Job *job;
 
     JOB_LOCK_GUARD();
     bjob = find_block_job_locked(id, errp);
 
     if (!bjob) {
         return;
     }
 
     trace_qmp_block_job_dismiss(bjob);
     job = &bjob->job;
     job_dismiss_locked(&job, errp);
 }
 
 void qmp_change_backing_file(const char *device,
                              const char *image_node_name,
                              const char *backing_file,
                              Error **errp)
 {
     BlockDriverState *bs = NULL;
     AioContext *aio_context;
     BlockDriverState *image_bs = NULL;
     Error *local_err = NULL;
     bool ro;
     int ret;
 
     bs = qmp_get_root_bs(device, errp);
     if (!bs) {
         return;
     }
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     image_bs = bdrv_lookup_bs(NULL, image_node_name, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto out;
     }
 
     if (!image_bs) {
         error_setg(errp, "image file not found");
         goto out;
     }
 
     if (bdrv_find_base(image_bs) == image_bs) {
         error_setg(errp, "not allowing backing file change on an image "
                          "without a backing file");
         goto out;
     }
 
     /* even though we are not necessarily operating on bs, we need it to
      * determine if block ops are currently prohibited on the chain */
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_CHANGE, errp)) {
         goto out;
     }
 
     /* final sanity check */
     if (!bdrv_chain_contains(bs, image_bs)) {
         error_setg(errp, "'%s' and image file are not in the same chain",
                    device);
         goto out;
     }
 
     /* if not r/w, reopen to make r/w */
     ro = bdrv_is_read_only(image_bs);
 
     if (ro) {
         if (bdrv_reopen_set_read_only(image_bs, false, errp) != 0) {
             goto out;
         }
     }
 
     ret = bdrv_change_backing_file(image_bs, backing_file,
                                    image_bs->drv ? image_bs->drv->format_name : "",
                                    false);
 
     if (ret < 0) {
         error_setg_errno(errp, -ret, "Could not change backing file to '%s'",
                          backing_file);
         /* don't exit here, so we can try to restore open flags if
          * appropriate */
     }
 
     if (ro) {
         bdrv_reopen_set_read_only(image_bs, true, errp);
     }
 
 out:
     aio_context_release(aio_context);
 }
 
 void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
 {
     BlockDriverState *bs;
     QObject *obj;
     Visitor *v = qobject_output_visitor_new(&obj);
     QDict *qdict;
 
     visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
     visit_complete(v, &obj);
     qdict = qobject_to(QDict, obj);
 
     qdict_flatten(qdict);
 
     if (!qdict_get_try_str(qdict, "node-name")) {
         error_setg(errp, "'node-name' must be specified for the root node");
         goto fail;
     }
 
     bs = bds_tree_init(qdict, errp);
     if (!bs) {
         goto fail;
     }
 
     bdrv_set_monitor_owned(bs);
 
 fail:
     visit_free(v);
 }
 
 void qmp_blockdev_reopen(BlockdevOptionsList *reopen_list, Error **errp)
 {
     BlockReopenQueue *queue = NULL;
     GSList *drained = NULL;
     GSList *p;
 
     /* Add each one of the BDS that we want to reopen to the queue */
     for (; reopen_list != NULL; reopen_list = reopen_list->next) {
         BlockdevOptions *options = reopen_list->value;
         BlockDriverState *bs;
         AioContext *ctx;
         QObject *obj;
         Visitor *v;
         QDict *qdict;
 
         /* Check for the selected node name */
         if (!options->has_node_name) {
             error_setg(errp, "node-name not specified");
             goto fail;
         }
 
         bs = bdrv_find_node(options->node_name);
         if (!bs) {
             error_setg(errp, "Failed to find node with node-name='%s'",
                        options->node_name);
             goto fail;
         }
 
         /* Put all options in a QDict and flatten it */
         v = qobject_output_visitor_new(&obj);
         visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
         visit_complete(v, &obj);
         visit_free(v);
 
         qdict = qobject_to(QDict, obj);
 
         qdict_flatten(qdict);
 
         ctx = bdrv_get_aio_context(bs);
         aio_context_acquire(ctx);
 
         bdrv_subtree_drained_begin(bs);
         queue = bdrv_reopen_queue(queue, bs, qdict, false);
         drained = g_slist_prepend(drained, bs);
 
         aio_context_release(ctx);
     }
 
     /* Perform the reopen operation */
     bdrv_reopen_multiple(queue, errp);
     queue = NULL;
 
 fail:
     bdrv_reopen_queue_free(queue);
     for (p = drained; p; p = p->next) {
         BlockDriverState *bs = p->data;
         AioContext *ctx = bdrv_get_aio_context(bs);
 
         aio_context_acquire(ctx);
         bdrv_subtree_drained_end(bs);
         aio_context_release(ctx);
     }
     g_slist_free(drained);
 }
 
 void qmp_blockdev_del(const char *node_name, Error **errp)
 {
     AioContext *aio_context;
     BlockDriverState *bs;
 
     GLOBAL_STATE_CODE();
 
     bs = bdrv_find_node(node_name);
     if (!bs) {
         error_setg(errp, "Failed to find node with node-name='%s'", node_name);
         return;
     }
     if (bdrv_has_blk(bs)) {
         error_setg(errp, "Node %s is in use", node_name);
         return;
     }
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
 
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_DRIVE_DEL, errp)) {
         goto out;
     }
 
     if (!QTAILQ_IN_USE(bs, monitor_list)) {
         error_setg(errp, "Node %s is not owned by the monitor",
                    bs->node_name);
         goto out;
     }
 
     if (bs->refcnt > 1) {
         error_setg(errp, "Block device %s is in use",
                    bdrv_get_device_or_node_name(bs));
         goto out;
     }
 
     QTAILQ_REMOVE(&monitor_bdrv_states, bs, monitor_list);
     bdrv_unref(bs);
 
 out:
     aio_context_release(aio_context);
 }
 
 static BdrvChild *bdrv_find_child(BlockDriverState *parent_bs,
                                   const char *child_name)
 {
     BdrvChild *child;
 
     QLIST_FOREACH(child, &parent_bs->children, next) {
         if (strcmp(child->name, child_name) == 0) {
             return child;
         }
     }
 
     return NULL;
 }
 
 void qmp_x_blockdev_change(const char *parent, bool has_child,
                            const char *child, bool has_node,
                            const char *node, Error **errp)
 {
     BlockDriverState *parent_bs, *new_bs = NULL;
     BdrvChild *p_child;
 
     parent_bs = bdrv_lookup_bs(parent, parent, errp);
     if (!parent_bs) {
         return;
     }
 
     if (has_child == has_node) {
         if (has_child) {
             error_setg(errp, "The parameters child and node are in conflict");
         } else {
             error_setg(errp, "Either child or node must be specified");
         }
         return;
     }
 
     if (has_child) {
         p_child = bdrv_find_child(parent_bs, child);
         if (!p_child) {
             error_setg(errp, "Node '%s' does not have child '%s'",
                        parent, child);
             return;
         }
         bdrv_del_child(parent_bs, p_child, errp);
     }
 
     if (has_node) {
         new_bs = bdrv_find_node(node);
         if (!new_bs) {
             error_setg(errp, "Node '%s' not found", node);
             return;
         }
         bdrv_add_child(parent_bs, new_bs, errp);
     }
 }
 
 BlockJobInfoList *qmp_query_block_jobs(Error **errp)
 {
     BlockJobInfoList *head = NULL, **tail = &head;
     BlockJob *job;
 
     JOB_LOCK_GUARD();
 
     for (job = block_job_next_locked(NULL); job;
          job = block_job_next_locked(job)) {
         BlockJobInfo *value;
 
         if (block_job_is_internal(job)) {
             continue;
         }
         value = block_job_query_locked(job, errp);
         if (!value) {
             qapi_free_BlockJobInfoList(head);
             return NULL;
         }
         QAPI_LIST_APPEND(tail, value);
     }
 
     return head;
 }
 
 void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,
                                  bool has_force, bool force, Error **errp)
 {
     AioContext *old_context;
     AioContext *new_context;
     BlockDriverState *bs;
 
     bs = bdrv_find_node(node_name);
     if (!bs) {
         error_setg(errp, "Failed to find node with node-name='%s'", node_name);
         return;
     }
 
     /* Protects against accidents. */
     if (!(has_force && force) && bdrv_has_blk(bs)) {
         error_setg(errp, "Node %s is associated with a BlockBackend and could "
                          "be in use (use force=true to override this check)",
                          node_name);
         return;
     }
 
     if (iothread->type == QTYPE_QSTRING) {
         IOThread *obj = iothread_by_id(iothread->u.s);
         if (!obj) {
             error_setg(errp, "Cannot find iothread %s", iothread->u.s);
             return;
         }
 
         new_context = iothread_get_aio_context(obj);
     } else {
         new_context = qemu_get_aio_context();
     }
 
     old_context = bdrv_get_aio_context(bs);
     aio_context_acquire(old_context);
 
     bdrv_try_change_aio_context(bs, new_context, NULL, errp);
 
     aio_context_release(old_context);
 }
 
 QemuOptsList qemu_common_drive_opts = {
     .name = "drive",
     .head = QTAILQ_HEAD_INITIALIZER(qemu_common_drive_opts.head),
     .desc = {
         {
             .name = "snapshot",
             .type = QEMU_OPT_BOOL,
             .help = "enable/disable snapshot mode",
         },{
             .name = "aio",
             .type = QEMU_OPT_STRING,
             .help = "host AIO implementation (threads, native, io_uring)",
         },{
             .name = BDRV_OPT_CACHE_WB,
             .type = QEMU_OPT_BOOL,
             .help = "Enable writeback mode",
         },{
             .name = "format",
             .type = QEMU_OPT_STRING,
             .help = "disk format (raw, qcow2, ...)",
         },{
             .name = "rerror",
             .type = QEMU_OPT_STRING,
             .help = "read error action",
         },{
             .name = "werror",
             .type = QEMU_OPT_STRING,
             .help = "write error action",
         },{
             .name = BDRV_OPT_READ_ONLY,
             .type = QEMU_OPT_BOOL,
             .help = "open drive file as read-only",
         },
 
         THROTTLE_OPTS,
 
         {
             .name = "throttling.group",
             .type = QEMU_OPT_STRING,
             .help = "name of the block throttling group",
         },{
             .name = "copy-on-read",
             .type = QEMU_OPT_BOOL,
             .help = "copy read data from backing file into image file",
         },{
             .name = "detect-zeroes",
             .type = QEMU_OPT_STRING,
             .help = "try to optimize zero writes (off, on, unmap)",
         },{
             .name = "stats-account-invalid",
             .type = QEMU_OPT_BOOL,
             .help = "whether to account for invalid I/O operations "
                     "in the statistics",
         },{
             .name = "stats-account-failed",
             .type = QEMU_OPT_BOOL,
             .help = "whether to account for failed I/O operations "
                     "in the statistics",
         },
         { /* end of list */ }
     },
 };
 
 QemuOptsList qemu_drive_opts = {
     .name = "drive",
     .head = QTAILQ_HEAD_INITIALIZER(qemu_drive_opts.head),
     .desc = {
         /*
          * no elements => accept any params
          * validation will happen later
          */
         { /* end of list */ }
     },
 };