27199bd753
This is necessary for multi-disk backups where not all jobs are immediately started after they are created. QEMU commit 06e0a9c16405c0a4c1eca33cf286cc04c42066a2 did already part of the work, ensuring that new writes after job creation don't pass through to the backup, but not yet for the MIRROR_SYNC_MODE_BITMAP case which is used for PBS. Signed-off-by: Fabian Ebner <f.ebner@proxmox.com> Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
59 lines
2.4 KiB
Diff
59 lines
2.4 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Fabian Ebner <f.ebner@proxmox.com>
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Date: Wed, 2 Mar 2022 08:35:05 +0100
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Subject: [PATCH] block/backup: move bcs bitmap initialization to job creation
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For backing up the state of multiple disks from the same time, a job
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for each disk has to be created. It's convenient if the jobs don't
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have to be started at the same time and if operation of the VM can be
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resumed after job creation. This would lead to a window between job
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creation and running the job, where writes can happen. But no writes
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should happen between setting up the copy-before-write filter and
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setting up the block copy state bitmap, because then new writes would
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just pass through.
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Commit 06e0a9c16405c0a4c1eca33cf286cc04c42066a2 moved initalization of
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the bitmap to setting up the copy-before-write filter when sync_mode
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is not MIRROR_SYNC_MODE_BITMAP. Ensure that the bitmap is initialized
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upon job creation for the remaining case too, by moving the
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backup_init_bcs_bitmap call to backup_job_create.
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Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
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---
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block/backup.c | 8 ++++----
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1 file changed, 4 insertions(+), 4 deletions(-)
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diff --git a/block/backup.c b/block/backup.c
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index 21d5983779..47e218857d 100644
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--- a/block/backup.c
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+++ b/block/backup.c
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@@ -239,8 +239,8 @@ static void backup_init_bcs_bitmap(BackupBlockJob *job)
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assert(ret);
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} else if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
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/*
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- * We can't hog the coroutine to initialize this thoroughly.
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- * Set a flag and resume work when we are able to yield safely.
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+ * Initialization is costly here. Simply set a flag and let the
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+ * backup_run coroutine resume work once it can yield safely.
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*/
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block_copy_set_skip_unallocated(job->bcs, true);
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}
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@@ -254,8 +254,6 @@ static int coroutine_fn backup_run(Job *job, Error **errp)
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BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
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int ret;
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- backup_init_bcs_bitmap(s);
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-
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if (s->sync_mode == MIRROR_SYNC_MODE_TOP) {
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int64_t offset = 0;
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int64_t count;
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@@ -493,6 +491,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
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block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
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&error_abort);
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+ backup_init_bcs_bitmap(job);
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+
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return &job->common;
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error:
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