[PATCH] blockcommit: Reopen base image as RO after abort

[Alexander Ivanov <alexander.ivanov@virtuozzo.com>]

If a blockcommit is aborted the base image remains in RW mode, that leads
to a fail of subsequent live migration.

How to reproduce:
  $ virsh snapshot-create-as vm snp1 --disk-only

  *** write something to the disk ***

  $ virsh blockcommit vm vda --active --shallow && virsh blockjob vm vda --abort
  $ lsof /vzt/vm.qcow2
  COMMAND      PID USER   FD   TYPE DEVICE   SIZE/OFF NODE NAME
  qemu-syst 433203 root   45u   REG  253,0 1724776448  133 /vzt/vm.qcow2
  $ cat /proc/433203/fdinfo/45
  pos:    0
  flags:  02140002

Reopen the base image in RO mode in mirror_exit_common() if the blockjob
is aborted.

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
 block/mirror.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block/mirror.c b/block/mirror.c
index dcd88de2e3..50a2825b1c 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -789,6 +789,10 @@ static int mirror_exit_common(Job *job)
     block_job_remove_all_bdrv(bjob);
     bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);
 
+    if (abort && !bdrv_is_read_only(target_bs)) {
+        bdrv_reopen_set_read_only(target_bs, true, NULL);
+    }
+
     bs_opaque->job = NULL;
 
     bdrv_drained_end(src);
-- 
2.39.2