We don't need or want a new sync mode for simple differences in semantics. Create a new mode simply named "BITMAP" that is designed to make use of the new Bitmap Sync Mode field. Because the only bitmap sync mode is 'on-success', this adds no new functionality to the backup job (yet). The old incremental backup mode is maintained as a syntactic sugar for sync=bitmap, mode=on-success. Add all of the plumbing necessary to support this new instruction. Signed-off-by: John Snow <jsnow@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: 20190709232550.10724-6-jsnow@redhat.com Signed-off-by: John Snow <jsnow@redhat.com>
694 lines
22 KiB
C
694 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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typedef struct CowRequest {
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int64_t start_byte;
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int64_t end_byte;
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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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BlockBackend *target;
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BdrvDirtyBitmap *sync_bitmap;
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MirrorSyncMode sync_mode;
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BitmapSyncMode bitmap_mode;
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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 len;
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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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bool use_copy_range;
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int64_t copy_range_size;
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bool serialize_target_writes;
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} BackupBlockJob;
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static const BlockJobDriver backup_job_driver;
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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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/* Copy range to target with a bounce buffer and return the bytes copied. If
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* error occurred, return a negative error number */
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static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
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int64_t start,
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int64_t end,
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bool is_write_notifier,
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bool *error_is_read,
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void **bounce_buffer)
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{
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int ret;
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BlockBackend *blk = job->common.blk;
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int nbytes;
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int read_flags = is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0;
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int write_flags = job->serialize_target_writes ? BDRV_REQ_SERIALISING : 0;
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assert(QEMU_IS_ALIGNED(start, job->cluster_size));
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hbitmap_reset(job->copy_bitmap, start, job->cluster_size);
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nbytes = MIN(job->cluster_size, job->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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ret = blk_co_pread(blk, start, nbytes, *bounce_buffer, read_flags);
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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 fail;
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}
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if (buffer_is_zero(*bounce_buffer, nbytes)) {
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ret = blk_co_pwrite_zeroes(job->target, start,
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nbytes, write_flags | BDRV_REQ_MAY_UNMAP);
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} else {
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ret = blk_co_pwrite(job->target, start,
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nbytes, *bounce_buffer, write_flags |
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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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goto fail;
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}
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return nbytes;
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fail:
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hbitmap_set(job->copy_bitmap, start, job->cluster_size);
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return ret;
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}
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/* Copy range to target and return the bytes copied. If error occurred, return a
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* negative error number. */
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static int coroutine_fn backup_cow_with_offload(BackupBlockJob *job,
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int64_t start,
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int64_t end,
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bool is_write_notifier)
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{
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int ret;
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int nr_clusters;
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BlockBackend *blk = job->common.blk;
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int nbytes;
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int read_flags = is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0;
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int write_flags = job->serialize_target_writes ? BDRV_REQ_SERIALISING : 0;
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assert(QEMU_IS_ALIGNED(job->copy_range_size, job->cluster_size));
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assert(QEMU_IS_ALIGNED(start, job->cluster_size));
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nbytes = MIN(job->copy_range_size, end - start);
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nr_clusters = DIV_ROUND_UP(nbytes, job->cluster_size);
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hbitmap_reset(job->copy_bitmap, start, job->cluster_size * nr_clusters);
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ret = blk_co_copy_range(blk, start, job->target, start, nbytes,
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read_flags, write_flags);
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if (ret < 0) {
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trace_backup_do_cow_copy_range_fail(job, start, ret);
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hbitmap_set(job->copy_bitmap, start, job->cluster_size * nr_clusters);
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return ret;
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}
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return nbytes;
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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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CowRequest cow_request;
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int ret = 0;
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int64_t start, end; /* bytes */
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void *bounce_buffer = NULL;
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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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while (start < end) {
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int64_t dirty_end;
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if (!hbitmap_get(job->copy_bitmap, start)) {
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trace_backup_do_cow_skip(job, start);
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start += job->cluster_size;
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continue; /* already copied */
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}
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dirty_end = hbitmap_next_zero(job->copy_bitmap, start, (end - start));
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if (dirty_end < 0) {
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dirty_end = end;
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}
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trace_backup_do_cow_process(job, start);
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if (job->use_copy_range) {
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ret = backup_cow_with_offload(job, start, dirty_end,
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is_write_notifier);
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if (ret < 0) {
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job->use_copy_range = false;
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}
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}
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if (!job->use_copy_range) {
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ret = backup_cow_with_bounce_buffer(job, start, dirty_end,
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is_write_notifier,
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error_is_read, &bounce_buffer);
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}
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if (ret < 0) {
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break;
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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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start += ret;
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job->bytes_read += ret;
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job_progress_update(&job->common.job, ret);
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ret = 0;
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}
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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_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) {
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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(Job *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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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(Job *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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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(Job *job)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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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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if (s->copy_bitmap) {
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hbitmap_free(s->copy_bitmap);
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s->copy_bitmap = NULL;
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}
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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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assert(block_job_driver(job) == &backup_job_driver);
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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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hbitmap_set(backup_job->copy_bitmap, 0, backup_job->len);
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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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static bool coroutine_fn yield_and_check(BackupBlockJob *job)
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{
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uint64_t delay_ns;
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if (job_is_cancelled(&job->common.job)) {
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return true;
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}
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/* We need to yield even for delay_ns = 0 so that bdrv_drain_all() can
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* return. Without a yield, the VM would not reboot. */
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delay_ns = block_job_ratelimit_get_delay(&job->common, job->bytes_read);
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job->bytes_read = 0;
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job_sleep_ns(&job->common.job, delay_ns);
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if (job_is_cancelled(&job->common.job)) {
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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 bool bdrv_is_unallocated_range(BlockDriverState *bs,
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int64_t offset, int64_t bytes)
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{
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int64_t end = offset + bytes;
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while (offset < end && !bdrv_is_allocated(bs, offset, bytes, &bytes)) {
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if (bytes == 0) {
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return true;
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}
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offset += bytes;
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bytes = end - offset;
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}
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return offset >= end;
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}
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static int coroutine_fn backup_loop(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 offset;
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HBitmapIter hbi;
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BlockDriverState *bs = blk_bs(job->common.blk);
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hbitmap_iter_init(&hbi, job->copy_bitmap, 0);
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while ((offset = hbitmap_iter_next(&hbi)) != -1) {
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if (job->sync_mode == MIRROR_SYNC_MODE_TOP &&
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bdrv_is_unallocated_range(bs, offset, job->cluster_size))
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{
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hbitmap_reset(job->copy_bitmap, offset, job->cluster_size);
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continue;
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}
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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, offset,
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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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uint64_t offset = 0;
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uint64_t bytes = job->len;
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while (bdrv_dirty_bitmap_next_dirty_area(job->sync_bitmap,
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&offset, &bytes))
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{
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hbitmap_set(job->copy_bitmap, offset, bytes);
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offset += bytes;
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if (offset >= job->len) {
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break;
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}
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bytes = job->len - offset;
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}
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/* TODO job_progress_set_remaining() would make more sense */
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job_progress_update(&job->common.job,
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job->len - hbitmap_count(job->copy_bitmap));
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}
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static int coroutine_fn backup_run(Job *job, Error **errp)
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{
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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BlockDriverState *bs = blk_bs(s->common.blk);
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int ret = 0;
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QLIST_INIT(&s->inflight_reqs);
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qemu_co_rwlock_init(&s->flush_rwlock);
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job_progress_set_remaining(job, s->len);
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if (s->sync_mode == MIRROR_SYNC_MODE_BITMAP) {
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backup_incremental_init_copy_bitmap(s);
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} else {
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hbitmap_set(s->copy_bitmap, 0, s->len);
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}
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s->before_write.notify = backup_before_write_notify;
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bdrv_add_before_write_notifier(bs, &s->before_write);
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if (s->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 (!job_is_cancelled(job)) {
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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_yield(job);
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}
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} else {
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ret = backup_loop(s);
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}
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notifier_with_return_remove(&s->before_write);
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/* wait until pending backup_do_cow() calls have completed */
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qemu_co_rwlock_wrlock(&s->flush_rwlock);
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qemu_co_rwlock_unlock(&s->flush_rwlock);
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return ret;
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}
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static const BlockJobDriver backup_job_driver = {
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.job_driver = {
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.instance_size = sizeof(BackupBlockJob),
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.job_type = JOB_TYPE_BACKUP,
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.free = block_job_free,
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.user_resume = block_job_user_resume,
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.drain = block_job_drain,
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.run = backup_run,
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|
.commit = backup_commit,
|
|
.abort = backup_abort,
|
|
.clean = backup_clean,
|
|
},
|
|
.drain = backup_drain,
|
|
};
|
|
|
|
static int64_t backup_calculate_cluster_size(BlockDriverState *target,
|
|
Error **errp)
|
|
{
|
|
int ret;
|
|
BlockDriverInfo bdi;
|
|
|
|
/*
|
|
* 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);
|
|
return 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");
|
|
return ret;
|
|
} else if (ret < 0 && target->backing) {
|
|
/* Not fatal; just trudge on ahead. */
|
|
return BACKUP_CLUSTER_SIZE_DEFAULT;
|
|
}
|
|
|
|
return MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
|
|
}
|
|
|
|
BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
|
|
BlockDriverState *target, int64_t speed,
|
|
MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
|
|
BitmapSyncMode bitmap_mode,
|
|
bool compress,
|
|
BlockdevOnError on_source_error,
|
|
BlockdevOnError on_target_error,
|
|
int creation_flags,
|
|
BlockCompletionFunc *cb, void *opaque,
|
|
JobTxn *txn, Error **errp)
|
|
{
|
|
int64_t len;
|
|
BackupBlockJob *job = NULL;
|
|
int ret;
|
|
int64_t cluster_size;
|
|
HBitmap *copy_bitmap = NULL;
|
|
|
|
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;
|
|
}
|
|
|
|
/* QMP interface should have handled translating this to bitmap mode */
|
|
assert(sync_mode != MIRROR_SYNC_MODE_INCREMENTAL);
|
|
|
|
if (sync_mode == MIRROR_SYNC_MODE_BITMAP) {
|
|
if (!sync_bitmap) {
|
|
error_setg(errp, "must provide a valid bitmap name for "
|
|
"'%s' sync mode", MirrorSyncMode_str(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 bitmap was given to backup_job_create, "
|
|
"but it 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;
|
|
}
|
|
|
|
cluster_size = backup_calculate_cluster_size(target, errp);
|
|
if (cluster_size < 0) {
|
|
goto error;
|
|
}
|
|
|
|
copy_bitmap = hbitmap_alloc(len, ctz32(cluster_size));
|
|
|
|
/* job->len is fixed, so we can't allow resize */
|
|
job = block_job_create(job_id, &backup_job_driver, txn, 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(job->common.job.aio_context,
|
|
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;
|
|
}
|
|
blk_set_disable_request_queuing(job->target, true);
|
|
|
|
job->on_source_error = on_source_error;
|
|
job->on_target_error = on_target_error;
|
|
job->sync_mode = sync_mode;
|
|
job->sync_bitmap = sync_bitmap;
|
|
job->bitmap_mode = bitmap_mode;
|
|
job->compress = compress;
|
|
|
|
/* Detect image-fleecing (and similar) schemes */
|
|
job->serialize_target_writes = bdrv_chain_contains(target, bs);
|
|
job->cluster_size = cluster_size;
|
|
job->copy_bitmap = copy_bitmap;
|
|
copy_bitmap = NULL;
|
|
job->use_copy_range = !compress; /* compression isn't supported for it */
|
|
job->copy_range_size = MIN_NON_ZERO(blk_get_max_transfer(job->common.blk),
|
|
blk_get_max_transfer(job->target));
|
|
job->copy_range_size = MAX(job->cluster_size,
|
|
QEMU_ALIGN_UP(job->copy_range_size,
|
|
job->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->len = len;
|
|
|
|
return &job->common;
|
|
|
|
error:
|
|
if (copy_bitmap) {
|
|
assert(!job || !job->copy_bitmap);
|
|
hbitmap_free(copy_bitmap);
|
|
}
|
|
if (sync_bitmap) {
|
|
bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
|
|
}
|
|
if (job) {
|
|
backup_clean(&job->common.job);
|
|
job_early_fail(&job->common.job);
|
|
}
|
|
|
|
return NULL;
|
|
}
|