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53f1c8794f
We can use copy_bitmap instead of sync_bitmap. copy_bitmap is initialized from sync_bitmap and it is more informative: we will not try to process data, that is already in progress (by write notifier). Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Jeff Cody <jcody@redhat.com> Message-id: 20171012135313.227864-6-vsementsov@virtuozzo.com Signed-off-by: Jeff Cody <jcody@redhat.com>
695 lines
22 KiB
C
695 lines
22 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 "qemu/osdep.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_int.h"
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#include "block/block_backup.h"
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#include "qapi/error.h"
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#include "qapi/qmp/qerror.h"
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#include "qemu/ratelimit.h"
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#include "qemu/cutils.h"
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#include "sysemu/block-backend.h"
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#include "qemu/bitmap.h"
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#include "qemu/error-report.h"
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#define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16)
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#define SLICE_TIME 100000000ULL /* ns */
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typedef struct BackupBlockJob {
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BlockJob common;
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BlockBackend *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 bytes_read;
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int64_t cluster_size;
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bool compress;
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NotifierWithReturn before_write;
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QLIST_HEAD(, CowRequest) inflight_reqs;
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HBitmap *copy_bitmap;
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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_byte && start < req->end_byte) {
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qemu_co_queue_wait(&req->wait_queue, NULL);
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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_byte = start;
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req->end_byte = 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(BackupBlockJob *job,
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int64_t offset, uint64_t bytes,
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bool *error_is_read,
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bool is_write_notifier)
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{
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BlockBackend *blk = job->common.blk;
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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; /* bytes */
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int n; /* bytes */
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qemu_co_rwlock_rdlock(&job->flush_rwlock);
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start = QEMU_ALIGN_DOWN(offset, job->cluster_size);
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end = QEMU_ALIGN_UP(bytes + offset, job->cluster_size);
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trace_backup_do_cow_enter(job, start, offset, bytes);
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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 += job->cluster_size) {
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if (!hbitmap_get(job->copy_bitmap, start / job->cluster_size)) {
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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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hbitmap_reset(job->copy_bitmap, start / job->cluster_size, 1);
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trace_backup_do_cow_process(job, start);
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n = MIN(job->cluster_size, job->common.len - start);
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if (!bounce_buffer) {
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bounce_buffer = blk_blockalign(blk, job->cluster_size);
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}
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iov.iov_base = bounce_buffer;
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iov.iov_len = n;
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qemu_iovec_init_external(&bounce_qiov, &iov, 1);
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ret = blk_co_preadv(blk, start, bounce_qiov.size, &bounce_qiov,
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is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0);
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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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hbitmap_set(job->copy_bitmap, start / job->cluster_size, 1);
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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 = blk_co_pwrite_zeroes(job->target, start,
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bounce_qiov.size, BDRV_REQ_MAY_UNMAP);
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} else {
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ret = blk_co_pwritev(job->target, start,
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bounce_qiov.size, &bounce_qiov,
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job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0);
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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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hbitmap_set(job->copy_bitmap, start / job->cluster_size, 1);
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goto out;
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}
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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->bytes_read += n;
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job->common.offset += n;
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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, offset, bytes, 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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BackupBlockJob *job = container_of(notifier, BackupBlockJob, before_write);
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BdrvTrackedRequest *req = opaque;
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assert(req->bs == blk_bs(job->common.blk));
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assert(QEMU_IS_ALIGNED(req->offset, BDRV_SECTOR_SIZE));
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assert(QEMU_IS_ALIGNED(req->bytes, BDRV_SECTOR_SIZE));
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return backup_do_cow(job, req->offset, req->bytes, 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, SLICE_TIME);
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}
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static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
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{
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BdrvDirtyBitmap *bm;
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BlockDriverState *bs = blk_bs(job->common.blk);
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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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static void backup_commit(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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if (s->sync_bitmap) {
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backup_cleanup_sync_bitmap(s, 0);
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}
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}
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static void backup_abort(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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if (s->sync_bitmap) {
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backup_cleanup_sync_bitmap(s, -1);
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}
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}
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static void backup_clean(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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assert(s->target);
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blk_unref(s->target);
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s->target = NULL;
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}
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static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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blk_set_aio_context(s->target, aio_context);
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}
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void backup_do_checkpoint(BlockJob *job, Error **errp)
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{
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BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
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int64_t len;
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assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
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if (backup_job->sync_mode != MIRROR_SYNC_MODE_NONE) {
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error_setg(errp, "The backup job only supports block checkpoint in"
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" sync=none mode");
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return;
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}
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len = DIV_ROUND_UP(backup_job->common.len, backup_job->cluster_size);
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hbitmap_set(backup_job->copy_bitmap, 0, len);
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}
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void backup_wait_for_overlapping_requests(BlockJob *job, int64_t offset,
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uint64_t bytes)
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{
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BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
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int64_t start, end;
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assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
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start = QEMU_ALIGN_DOWN(offset, backup_job->cluster_size);
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end = QEMU_ALIGN_UP(offset + bytes, backup_job->cluster_size);
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wait_for_overlapping_requests(backup_job, start, end);
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}
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void backup_cow_request_begin(CowRequest *req, BlockJob *job,
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int64_t offset, uint64_t bytes)
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{
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BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
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int64_t start, end;
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assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
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start = QEMU_ALIGN_DOWN(offset, backup_job->cluster_size);
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end = QEMU_ALIGN_UP(offset + bytes, backup_job->cluster_size);
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cow_request_begin(req, backup_job, start, end);
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}
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void backup_cow_request_end(CowRequest *req)
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{
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cow_request_end(req);
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}
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static void backup_drain(BlockJob *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common);
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/* Need to keep a reference in case blk_drain triggers execution
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* of backup_complete...
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*/
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if (s->target) {
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BlockBackend *target = s->target;
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blk_ref(target);
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blk_drain(target);
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blk_unref(target);
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}
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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->on_source_error,
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true, error);
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} else {
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return block_job_error_action(&job->common, job->on_target_error,
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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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BackupCompleteData *data = opaque;
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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->bytes_read);
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job->bytes_read = 0;
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block_job_sleep_ns(&job->common, delay_ns);
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} else {
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block_job_sleep_ns(&job->common, 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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int ret;
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bool error_is_read;
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int64_t cluster;
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HBitmapIter hbi;
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hbitmap_iter_init(&hbi, job->copy_bitmap, 0);
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while ((cluster = hbitmap_iter_next(&hbi)) != -1) {
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do {
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if (yield_and_check(job)) {
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return 0;
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}
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ret = backup_do_cow(job, cluster * job->cluster_size,
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job->cluster_size, &error_is_read, false);
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if (ret < 0 && backup_error_action(job, error_is_read, -ret) ==
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BLOCK_ERROR_ACTION_REPORT)
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{
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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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return 0;
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}
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/* init copy_bitmap from sync_bitmap */
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static void backup_incremental_init_copy_bitmap(BackupBlockJob *job)
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{
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BdrvDirtyBitmapIter *dbi;
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int64_t offset;
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int64_t end = DIV_ROUND_UP(bdrv_dirty_bitmap_size(job->sync_bitmap),
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job->cluster_size);
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dbi = bdrv_dirty_iter_new(job->sync_bitmap);
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while ((offset = bdrv_dirty_iter_next(dbi)) != -1) {
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int64_t cluster = offset / job->cluster_size;
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int64_t next_cluster;
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offset += bdrv_dirty_bitmap_granularity(job->sync_bitmap);
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if (offset >= bdrv_dirty_bitmap_size(job->sync_bitmap)) {
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hbitmap_set(job->copy_bitmap, cluster, end - cluster);
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break;
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}
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offset = bdrv_dirty_bitmap_next_zero(job->sync_bitmap, offset);
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if (offset == -1) {
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hbitmap_set(job->copy_bitmap, cluster, end - cluster);
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break;
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}
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next_cluster = DIV_ROUND_UP(offset, job->cluster_size);
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hbitmap_set(job->copy_bitmap, cluster, next_cluster - cluster);
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if (next_cluster >= end) {
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break;
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}
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bdrv_set_dirty_iter(dbi, next_cluster * job->cluster_size);
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}
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job->common.offset = job->common.len -
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hbitmap_count(job->copy_bitmap) * job->cluster_size;
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bdrv_dirty_iter_free(dbi);
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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 = blk_bs(job->common.blk);
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int64_t offset, nb_clusters;
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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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nb_clusters = DIV_ROUND_UP(job->common.len, job->cluster_size);
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job->copy_bitmap = hbitmap_alloc(nb_clusters, 0);
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if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
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backup_incremental_init_copy_bitmap(job);
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} else {
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hbitmap_set(job->copy_bitmap, 0, nb_clusters);
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}
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job->before_write.notify = backup_before_write_notify;
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bdrv_add_before_write_notifier(bs, &job->before_write);
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if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
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/* All bits are set in copy_bitmap to allow any cluster to be copied.
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* This does not actually require them to be copied. */
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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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block_job_yield(&job->common);
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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 (offset = 0; offset < job->common.len;
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offset += job->cluster_size) {
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bool error_is_read;
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int alloced = 0;
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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;
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int64_t n;
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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 < job->cluster_size;) {
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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 =
|
|
bdrv_is_allocated(bs, offset + i,
|
|
job->cluster_size - i, &n);
|
|
i += n;
|
|
|
|
if (alloced || n == 0) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If the above loop never found any sectors that are in
|
|
* the topmost image, skip this backup. */
|
|
if (alloced == 0) {
|
|
continue;
|
|
}
|
|
}
|
|
/* FULL sync mode we copy the whole drive. */
|
|
if (alloced < 0) {
|
|
ret = alloced;
|
|
} else {
|
|
ret = backup_do_cow(job, offset, job->cluster_size,
|
|
&error_is_read, false);
|
|
}
|
|
if (ret < 0) {
|
|
/* Depending on error action, fail now or retry cluster */
|
|
BlockErrorAction action =
|
|
backup_error_action(job, error_is_read, -ret);
|
|
if (action == BLOCK_ERROR_ACTION_REPORT) {
|
|
break;
|
|
} else {
|
|
offset -= job->cluster_size;
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
notifier_with_return_remove(&job->before_write);
|
|
|
|
/* wait until pending backup_do_cow() calls have completed */
|
|
qemu_co_rwlock_wrlock(&job->flush_rwlock);
|
|
qemu_co_rwlock_unlock(&job->flush_rwlock);
|
|
hbitmap_free(job->copy_bitmap);
|
|
|
|
data = g_malloc(sizeof(*data));
|
|
data->ret = ret;
|
|
block_job_defer_to_main_loop(&job->common, backup_complete, data);
|
|
}
|
|
|
|
static const BlockJobDriver backup_job_driver = {
|
|
.instance_size = sizeof(BackupBlockJob),
|
|
.job_type = BLOCK_JOB_TYPE_BACKUP,
|
|
.start = backup_run,
|
|
.set_speed = backup_set_speed,
|
|
.commit = backup_commit,
|
|
.abort = backup_abort,
|
|
.clean = backup_clean,
|
|
.attached_aio_context = backup_attached_aio_context,
|
|
.drain = backup_drain,
|
|
};
|
|
|
|
BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
|
|
BlockDriverState *target, int64_t speed,
|
|
MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
|
|
bool compress,
|
|
BlockdevOnError on_source_error,
|
|
BlockdevOnError on_target_error,
|
|
int creation_flags,
|
|
BlockCompletionFunc *cb, void *opaque,
|
|
BlockJobTxn *txn, Error **errp)
|
|
{
|
|
int64_t len;
|
|
BlockDriverInfo bdi;
|
|
BackupBlockJob *job = NULL;
|
|
int ret;
|
|
|
|
assert(bs);
|
|
assert(target);
|
|
|
|
if (bs == target) {
|
|
error_setg(errp, "Source and target cannot be the same");
|
|
return NULL;
|
|
}
|
|
|
|
if (!bdrv_is_inserted(bs)) {
|
|
error_setg(errp, "Device is not inserted: %s",
|
|
bdrv_get_device_name(bs));
|
|
return NULL;
|
|
}
|
|
|
|
if (!bdrv_is_inserted(target)) {
|
|
error_setg(errp, "Device is not inserted: %s",
|
|
bdrv_get_device_name(target));
|
|
return NULL;
|
|
}
|
|
|
|
if (compress && target->drv->bdrv_co_pwritev_compressed == NULL) {
|
|
error_setg(errp, "Compression is not supported for this drive %s",
|
|
bdrv_get_device_name(target));
|
|
return NULL;
|
|
}
|
|
|
|
if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
|
|
return NULL;
|
|
}
|
|
|
|
if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
|
|
return NULL;
|
|
}
|
|
|
|
if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
|
|
if (!sync_bitmap) {
|
|
error_setg(errp, "must provide a valid bitmap name for "
|
|
"\"incremental\" sync mode");
|
|
return NULL;
|
|
}
|
|
|
|
/* Create a new bitmap, and freeze/disable this one. */
|
|
if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
|
|
return NULL;
|
|
}
|
|
} else if (sync_bitmap) {
|
|
error_setg(errp,
|
|
"a sync_bitmap was provided to backup_run, "
|
|
"but received an incompatible sync_mode (%s)",
|
|
MirrorSyncMode_str(sync_mode));
|
|
return NULL;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/* job->common.len is fixed, so we can't allow resize */
|
|
job = block_job_create(job_id, &backup_job_driver, bs,
|
|
BLK_PERM_CONSISTENT_READ,
|
|
BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE |
|
|
BLK_PERM_WRITE_UNCHANGED | BLK_PERM_GRAPH_MOD,
|
|
speed, creation_flags, cb, opaque, errp);
|
|
if (!job) {
|
|
goto error;
|
|
}
|
|
|
|
/* The target must match the source in size, so no resize here either */
|
|
job->target = blk_new(BLK_PERM_WRITE,
|
|
BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE |
|
|
BLK_PERM_WRITE_UNCHANGED | BLK_PERM_GRAPH_MOD);
|
|
ret = blk_insert_bs(job->target, target, errp);
|
|
if (ret < 0) {
|
|
goto error;
|
|
}
|
|
|
|
job->on_source_error = on_source_error;
|
|
job->on_target_error = on_target_error;
|
|
job->sync_mode = sync_mode;
|
|
job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
|
|
sync_bitmap : NULL;
|
|
job->compress = compress;
|
|
|
|
/* If there is no backing file on the target, we cannot rely on COW if our
|
|
* backup cluster size is smaller than the target cluster size. Even for
|
|
* targets with a backing file, try to avoid COW if possible. */
|
|
ret = bdrv_get_info(target, &bdi);
|
|
if (ret == -ENOTSUP && !target->backing) {
|
|
/* Cluster size is not defined */
|
|
warn_report("The target block device doesn't provide "
|
|
"information about the block size and it doesn't have a "
|
|
"backing file. The default block size of %u bytes is "
|
|
"used. If the actual block size of the target exceeds "
|
|
"this default, the backup may be unusable",
|
|
BACKUP_CLUSTER_SIZE_DEFAULT);
|
|
job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT;
|
|
} else if (ret < 0 && !target->backing) {
|
|
error_setg_errno(errp, -ret,
|
|
"Couldn't determine the cluster size of the target image, "
|
|
"which has no backing file");
|
|
error_append_hint(errp,
|
|
"Aborting, since this may create an unusable destination image\n");
|
|
goto error;
|
|
} else if (ret < 0 && target->backing) {
|
|
/* Not fatal; just trudge on ahead. */
|
|
job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT;
|
|
} else {
|
|
job->cluster_size = MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
|
|
}
|
|
|
|
/* Required permissions are already taken with target's blk_new() */
|
|
block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
|
|
&error_abort);
|
|
job->common.len = len;
|
|
block_job_txn_add_job(txn, &job->common);
|
|
|
|
return &job->common;
|
|
|
|
error:
|
|
if (sync_bitmap) {
|
|
bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
|
|
}
|
|
if (job) {
|
|
backup_clean(&job->common);
|
|
block_job_early_fail(&job->common);
|
|
}
|
|
|
|
return NULL;
|
|
}
|