mirror of https://gitee.com/openkylin/qemu.git
558 lines
17 KiB
C
558 lines
17 KiB
C
/*
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* QEMU backup
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*
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* Copyright (C) 2013 Proxmox Server Solutions
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*
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* Authors:
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* Dietmar Maurer (dietmar@proxmox.com)
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include <stdio.h>
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#include <errno.h>
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#include <unistd.h>
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#include "trace.h"
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#include "block/block.h"
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#include "block/block_int.h"
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#include "block/blockjob.h"
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#include "qapi/qmp/qerror.h"
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#include "qemu/ratelimit.h"
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#define BACKUP_CLUSTER_BITS 16
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#define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS)
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#define BACKUP_SECTORS_PER_CLUSTER (BACKUP_CLUSTER_SIZE / BDRV_SECTOR_SIZE)
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#define SLICE_TIME 100000000ULL /* ns */
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typedef struct CowRequest {
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int64_t start;
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int64_t end;
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QLIST_ENTRY(CowRequest) list;
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CoQueue wait_queue; /* coroutines blocked on this request */
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} CowRequest;
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typedef struct BackupBlockJob {
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BlockJob common;
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BlockDriverState *target;
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/* bitmap for sync=incremental */
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BdrvDirtyBitmap *sync_bitmap;
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MirrorSyncMode sync_mode;
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RateLimit limit;
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BlockdevOnError on_source_error;
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BlockdevOnError on_target_error;
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CoRwlock flush_rwlock;
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uint64_t sectors_read;
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HBitmap *bitmap;
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QLIST_HEAD(, CowRequest) inflight_reqs;
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} BackupBlockJob;
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/* See if in-flight requests overlap and wait for them to complete */
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static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
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int64_t start,
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int64_t end)
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{
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CowRequest *req;
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bool retry;
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do {
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retry = false;
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QLIST_FOREACH(req, &job->inflight_reqs, list) {
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if (end > req->start && start < req->end) {
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qemu_co_queue_wait(&req->wait_queue);
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retry = true;
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break;
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}
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}
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} while (retry);
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}
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/* Keep track of an in-flight request */
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static void cow_request_begin(CowRequest *req, BackupBlockJob *job,
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int64_t start, int64_t end)
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{
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req->start = start;
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req->end = end;
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qemu_co_queue_init(&req->wait_queue);
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QLIST_INSERT_HEAD(&job->inflight_reqs, req, list);
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}
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/* Forget about a completed request */
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static void cow_request_end(CowRequest *req)
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{
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QLIST_REMOVE(req, list);
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qemu_co_queue_restart_all(&req->wait_queue);
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}
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static int coroutine_fn backup_do_cow(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors,
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bool *error_is_read,
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bool is_write_notifier)
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{
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BackupBlockJob *job = (BackupBlockJob *)bs->job;
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CowRequest cow_request;
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struct iovec iov;
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QEMUIOVector bounce_qiov;
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void *bounce_buffer = NULL;
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int ret = 0;
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int64_t start, end;
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int n;
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qemu_co_rwlock_rdlock(&job->flush_rwlock);
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start = sector_num / BACKUP_SECTORS_PER_CLUSTER;
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end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER);
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trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
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wait_for_overlapping_requests(job, start, end);
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cow_request_begin(&cow_request, job, start, end);
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for (; start < end; start++) {
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if (hbitmap_get(job->bitmap, start)) {
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trace_backup_do_cow_skip(job, start);
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continue; /* already copied */
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}
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trace_backup_do_cow_process(job, start);
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n = MIN(BACKUP_SECTORS_PER_CLUSTER,
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job->common.len / BDRV_SECTOR_SIZE -
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start * BACKUP_SECTORS_PER_CLUSTER);
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if (!bounce_buffer) {
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bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE);
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}
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iov.iov_base = bounce_buffer;
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iov.iov_len = n * BDRV_SECTOR_SIZE;
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qemu_iovec_init_external(&bounce_qiov, &iov, 1);
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if (is_write_notifier) {
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ret = bdrv_co_no_copy_on_readv(bs,
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start * BACKUP_SECTORS_PER_CLUSTER,
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n, &bounce_qiov);
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} else {
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ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
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&bounce_qiov);
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}
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if (ret < 0) {
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trace_backup_do_cow_read_fail(job, start, ret);
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if (error_is_read) {
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*error_is_read = true;
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}
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goto out;
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}
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if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
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ret = bdrv_co_write_zeroes(job->target,
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start * BACKUP_SECTORS_PER_CLUSTER,
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n, BDRV_REQ_MAY_UNMAP);
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} else {
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ret = bdrv_co_writev(job->target,
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start * BACKUP_SECTORS_PER_CLUSTER, n,
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&bounce_qiov);
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}
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if (ret < 0) {
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trace_backup_do_cow_write_fail(job, start, ret);
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if (error_is_read) {
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*error_is_read = false;
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}
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goto out;
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}
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hbitmap_set(job->bitmap, start, 1);
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/* Publish progress, guest I/O counts as progress too. Note that the
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* offset field is an opaque progress value, it is not a disk offset.
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*/
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job->sectors_read += n;
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job->common.offset += n * BDRV_SECTOR_SIZE;
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}
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out:
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if (bounce_buffer) {
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qemu_vfree(bounce_buffer);
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}
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cow_request_end(&cow_request);
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trace_backup_do_cow_return(job, sector_num, nb_sectors, ret);
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qemu_co_rwlock_unlock(&job->flush_rwlock);
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return ret;
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}
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static int coroutine_fn backup_before_write_notify(
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NotifierWithReturn *notifier,
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void *opaque)
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{
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BdrvTrackedRequest *req = opaque;
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int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
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int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
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assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
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assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
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return backup_do_cow(req->bs, sector_num, nb_sectors, NULL, true);
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}
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static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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if (speed < 0) {
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error_setg(errp, QERR_INVALID_PARAMETER, "speed");
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return;
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}
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ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
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}
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static void backup_iostatus_reset(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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bdrv_iostatus_reset(s->target);
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}
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static const BlockJobDriver backup_job_driver = {
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.instance_size = sizeof(BackupBlockJob),
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.job_type = BLOCK_JOB_TYPE_BACKUP,
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.set_speed = backup_set_speed,
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.iostatus_reset = backup_iostatus_reset,
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};
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static BlockErrorAction backup_error_action(BackupBlockJob *job,
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bool read, int error)
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{
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if (read) {
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return block_job_error_action(&job->common, job->common.bs,
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job->on_source_error, true, error);
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} else {
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return block_job_error_action(&job->common, job->target,
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job->on_target_error, false, error);
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}
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}
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typedef struct {
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int ret;
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} BackupCompleteData;
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static void backup_complete(BlockJob *job, void *opaque)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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BackupCompleteData *data = opaque;
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bdrv_unref(s->target);
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block_job_completed(job, data->ret);
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g_free(data);
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}
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static bool coroutine_fn yield_and_check(BackupBlockJob *job)
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{
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if (block_job_is_cancelled(&job->common)) {
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return true;
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}
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/* we need to yield so that bdrv_drain_all() returns.
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* (without, VM does not reboot)
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*/
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if (job->common.speed) {
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uint64_t delay_ns = ratelimit_calculate_delay(&job->limit,
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job->sectors_read);
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job->sectors_read = 0;
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block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
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} else {
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block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);
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}
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if (block_job_is_cancelled(&job->common)) {
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return true;
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}
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return false;
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}
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static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
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{
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bool error_is_read;
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int ret = 0;
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int clusters_per_iter;
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uint32_t granularity;
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int64_t sector;
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int64_t cluster;
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int64_t end;
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int64_t last_cluster = -1;
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BlockDriverState *bs = job->common.bs;
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HBitmapIter hbi;
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granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
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clusters_per_iter = MAX((granularity / BACKUP_CLUSTER_SIZE), 1);
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bdrv_dirty_iter_init(job->sync_bitmap, &hbi);
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/* Find the next dirty sector(s) */
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while ((sector = hbitmap_iter_next(&hbi)) != -1) {
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cluster = sector / BACKUP_SECTORS_PER_CLUSTER;
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/* Fake progress updates for any clusters we skipped */
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if (cluster != last_cluster + 1) {
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job->common.offset += ((cluster - last_cluster - 1) *
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BACKUP_CLUSTER_SIZE);
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}
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for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
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do {
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if (yield_and_check(job)) {
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return ret;
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}
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ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
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BACKUP_SECTORS_PER_CLUSTER, &error_is_read,
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false);
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if ((ret < 0) &&
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backup_error_action(job, error_is_read, -ret) ==
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BLOCK_ERROR_ACTION_REPORT) {
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return ret;
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}
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} while (ret < 0);
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}
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/* If the bitmap granularity is smaller than the backup granularity,
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* we need to advance the iterator pointer to the next cluster. */
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if (granularity < BACKUP_CLUSTER_SIZE) {
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bdrv_set_dirty_iter(&hbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
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}
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last_cluster = cluster - 1;
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}
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/* Play some final catchup with the progress meter */
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end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
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if (last_cluster + 1 < end) {
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job->common.offset += ((end - last_cluster - 1) * BACKUP_CLUSTER_SIZE);
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}
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return ret;
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}
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static void coroutine_fn backup_run(void *opaque)
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{
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BackupBlockJob *job = opaque;
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BackupCompleteData *data;
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BlockDriverState *bs = job->common.bs;
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BlockDriverState *target = job->target;
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BlockdevOnError on_target_error = job->on_target_error;
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NotifierWithReturn before_write = {
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.notify = backup_before_write_notify,
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};
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int64_t start, end;
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int ret = 0;
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QLIST_INIT(&job->inflight_reqs);
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qemu_co_rwlock_init(&job->flush_rwlock);
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start = 0;
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end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
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job->bitmap = hbitmap_alloc(end, 0);
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bdrv_set_enable_write_cache(target, true);
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bdrv_set_on_error(target, on_target_error, on_target_error);
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bdrv_iostatus_enable(target);
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bdrv_add_before_write_notifier(bs, &before_write);
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if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
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while (!block_job_is_cancelled(&job->common)) {
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/* Yield until the job is cancelled. We just let our before_write
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* notify callback service CoW requests. */
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job->common.busy = false;
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qemu_coroutine_yield();
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job->common.busy = true;
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}
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} else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
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ret = backup_run_incremental(job);
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} else {
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/* Both FULL and TOP SYNC_MODE's require copying.. */
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for (; start < end; start++) {
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bool error_is_read;
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if (yield_and_check(job)) {
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break;
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}
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if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
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int i, n;
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int alloced = 0;
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/* Check to see if these blocks are already in the
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* backing file. */
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for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
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/* bdrv_is_allocated() only returns true/false based
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* on the first set of sectors it comes across that
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* are are all in the same state.
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* For that reason we must verify each sector in the
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* backup cluster length. We end up copying more than
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* needed but at some point that is always the case. */
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alloced =
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bdrv_is_allocated(bs,
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start * BACKUP_SECTORS_PER_CLUSTER + i,
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BACKUP_SECTORS_PER_CLUSTER - i, &n);
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i += n;
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if (alloced == 1 || n == 0) {
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break;
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}
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}
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/* If the above loop never found any sectors that are in
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* the topmost image, skip this backup. */
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if (alloced == 0) {
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continue;
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}
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}
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/* FULL sync mode we copy the whole drive. */
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ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
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BACKUP_SECTORS_PER_CLUSTER, &error_is_read, false);
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if (ret < 0) {
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/* Depending on error action, fail now or retry cluster */
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BlockErrorAction action =
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backup_error_action(job, error_is_read, -ret);
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if (action == BLOCK_ERROR_ACTION_REPORT) {
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break;
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} else {
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start--;
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continue;
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}
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}
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}
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}
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notifier_with_return_remove(&before_write);
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/* wait until pending backup_do_cow() calls have completed */
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qemu_co_rwlock_wrlock(&job->flush_rwlock);
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qemu_co_rwlock_unlock(&job->flush_rwlock);
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if (job->sync_bitmap) {
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BdrvDirtyBitmap *bm;
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if (ret < 0 || block_job_is_cancelled(&job->common)) {
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/* Merge the successor back into the parent, delete nothing. */
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bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
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assert(bm);
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} else {
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/* Everything is fine, delete this bitmap and install the backup. */
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bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL);
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assert(bm);
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}
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}
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hbitmap_free(job->bitmap);
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bdrv_iostatus_disable(target);
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bdrv_op_unblock_all(target, job->common.blocker);
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data = g_malloc(sizeof(*data));
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data->ret = ret;
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block_job_defer_to_main_loop(&job->common, backup_complete, data);
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}
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void backup_start(BlockDriverState *bs, BlockDriverState *target,
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int64_t speed, MirrorSyncMode sync_mode,
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BdrvDirtyBitmap *sync_bitmap,
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BlockdevOnError on_source_error,
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BlockdevOnError on_target_error,
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BlockCompletionFunc *cb, void *opaque,
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Error **errp)
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{
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int64_t len;
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assert(bs);
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assert(target);
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assert(cb);
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if (bs == target) {
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error_setg(errp, "Source and target cannot be the same");
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return;
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}
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if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
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on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
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!bdrv_iostatus_is_enabled(bs)) {
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error_setg(errp, QERR_INVALID_PARAMETER, "on-source-error");
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return;
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}
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if (!bdrv_is_inserted(bs)) {
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error_setg(errp, "Device is not inserted: %s",
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bdrv_get_device_name(bs));
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return;
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}
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if (!bdrv_is_inserted(target)) {
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error_setg(errp, "Device is not inserted: %s",
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bdrv_get_device_name(target));
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return;
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}
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if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
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return;
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}
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if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
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return;
|
|
}
|
|
|
|
if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
|
|
if (!sync_bitmap) {
|
|
error_setg(errp, "must provide a valid bitmap name for "
|
|
"\"incremental\" sync mode");
|
|
return;
|
|
}
|
|
|
|
/* Create a new bitmap, and freeze/disable this one. */
|
|
if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
|
|
return;
|
|
}
|
|
} else if (sync_bitmap) {
|
|
error_setg(errp,
|
|
"a sync_bitmap was provided to backup_run, "
|
|
"but received an incompatible sync_mode (%s)",
|
|
MirrorSyncMode_lookup[sync_mode]);
|
|
return;
|
|
}
|
|
|
|
len = bdrv_getlength(bs);
|
|
if (len < 0) {
|
|
error_setg_errno(errp, -len, "unable to get length for '%s'",
|
|
bdrv_get_device_name(bs));
|
|
goto error;
|
|
}
|
|
|
|
BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
|
|
cb, opaque, errp);
|
|
if (!job) {
|
|
goto error;
|
|
}
|
|
|
|
bdrv_op_block_all(target, job->common.blocker);
|
|
|
|
job->on_source_error = on_source_error;
|
|
job->on_target_error = on_target_error;
|
|
job->target = target;
|
|
job->sync_mode = sync_mode;
|
|
job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
|
|
sync_bitmap : NULL;
|
|
job->common.len = len;
|
|
job->common.co = qemu_coroutine_create(backup_run);
|
|
qemu_coroutine_enter(job->common.co, job);
|
|
return;
|
|
|
|
error:
|
|
if (sync_bitmap) {
|
|
bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
|
|
}
|
|
}
|