fix backup speed regression

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

debian/patches/pve/0041-PVE-backup-consider-source-cluster-size-as-well.patch

@@ -0,0 +1,28 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Wolfgang Bumiller <w.bumiller@proxmox.com>
+Date: Mon, 4 Nov 2019 14:18:40 +0100
+Subject: [PATCH] PVE: backup: consider source cluster size as well
+
+Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
+---
+ block/backup.c | 7 ++-----
+ 1 file changed, 2 insertions(+), 5 deletions(-)
+
+diff --git a/block/backup.c b/block/backup.c
+index cc20d77b9f..cdf815816f 100644
+--- a/block/backup.c
++++ b/block/backup.c
+@@ -655,11 +655,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
+         goto error;
+     }
+ 
+-    if (target) {
+-        cluster_size = backup_calculate_cluster_size(target, errp);
+-    } else {
+-        cluster_size = dump_cb_block_size;
+-    }
++    cluster_size = backup_calculate_cluster_size(target ? target : bs, errp);
++    cluster_size = MAX(cluster_size, dump_cb_block_size);
+ 
+     if (cluster_size < 0) {
+         goto error;

debian/patches/series

@@ -39,3 +39,4 @@ pve/0037-rename-config_to_vma-into-pvebackup_co_add_config.patch
 pve/0038-pvebackup_co_dump_cb-do-not-call-job-cancel.patch
 pve/0039-fix-backup-job-completion.patch
 pve/0040-pvebackup_complete_cb-avoid-poll-loop-if-already-ins.patch
+pve/0041-PVE-backup-consider-source-cluster-size-as-well.patch