pve-qemu-qoup/debian/patches/pve/0036-avoid-calling-dump_cb-with-NULL-data-pointer-for-sma.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Thu, 24 Oct 2019 08:06:51 +0200
Subject: [PATCH] avoid calling dump_cb with NULL data pointer for small/last
 cluster

The last block of a backup may be smaller than cluster_size.

Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
---
 block/backup.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/backup.c b/block/backup.c
index 2398a4d602..c682c99f7a 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -131,7 +131,12 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
 
     if (buffer_is_zero(*bounce_buffer, nbytes)) {
         if (job->dump_cb) {
-            ret = job->dump_cb(job->common.job.opaque, job->target, start, nbytes, NULL);
+            if (nbytes == job->cluster_size) {
+                // Note: pass NULL to indicate that we want to write [0u8; cluster_size]
+                ret = job->dump_cb(job->common.job.opaque, job->target, start, nbytes, NULL);
+            } else {
+                ret = job->dump_cb(job->common.job.opaque, job->target, start, nbytes, *bounce_buffer);
+            }
         } else {
             ret = blk_co_pwrite_zeroes(job->target, start,
                                        nbytes, write_flags | BDRV_REQ_MAY_UNMAP);