1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
2 From: Fabian Ebner <f.ebner@proxmox.com>
3 Date: Wed, 2 Mar 2022 08:35:05 +0100
4 Subject: [PATCH] block/backup: move bcs bitmap initialization to job creation
6 For backing up the state of multiple disks from the same time, a job
7 for each disk has to be created. It's convenient if the jobs don't
8 have to be started at the same time and if operation of the VM can be
9 resumed after job creation. This would lead to a window between job
10 creation and running the job, where writes can happen. But no writes
11 should happen between setting up the copy-before-write filter and
12 setting up the block copy state bitmap, because then new writes would
15 Commit 06e0a9c16405c0a4c1eca33cf286cc04c42066a2 moved initalization of
16 the bitmap to setting up the copy-before-write filter when sync_mode
17 is not MIRROR_SYNC_MODE_BITMAP. Ensure that the bitmap is initialized
18 upon job creation for the remaining case too, by moving the
19 backup_init_bcs_bitmap call to backup_job_create.
21 Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
23 block/backup.c | 8 ++++----
24 1 file changed, 4 insertions(+), 4 deletions(-)
26 diff --git a/block/backup.c b/block/backup.c
27 index 21d5983779..47e218857d 100644
30 @@ -239,8 +239,8 @@ static void backup_init_bcs_bitmap(BackupBlockJob *job)
32 } else if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
34 - * We can't hog the coroutine to initialize this thoroughly.
35 - * Set a flag and resume work when we are able to yield safely.
36 + * Initialization is costly here. Simply set a flag and let the
37 + * backup_run coroutine resume work once it can yield safely.
39 block_copy_set_skip_unallocated(job->bcs, true);
41 @@ -254,8 +254,6 @@ static int coroutine_fn backup_run(Job *job, Error **errp)
42 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
45 - backup_init_bcs_bitmap(s);
47 if (s->sync_mode == MIRROR_SYNC_MODE_TOP) {
50 @@ -493,6 +491,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
51 block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
54 + backup_init_bcs_bitmap(job);