[Qemu-block] [RFC PATCH v2 02/12] block: Freeze the backing chain for the duration of the commit job

[Alberto Garcia]

Signed-off-by: Alberto Garcia <address@hidden>
---
 block/commit.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/commit.c b/block/commit.c
index 53148e610b..8824d135e0 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -73,6 +73,8 @@ static int commit_prepare(Job *job)
 {
     CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
 
+    bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs);
+
     /* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before
      * the normal backing chain can be restored. */
     blk_unref(s->base);
@@ -89,6 +91,8 @@ static void commit_abort(Job *job)
     CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
     BlockDriverState *top_bs = blk_bs(s->top);
 
+    bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs);
+
     /* Make sure commit_top_bs and top stay around until bdrv_replace_node() */
     bdrv_ref(top_bs);
     bdrv_ref(s->commit_top_bs);
@@ -336,6 +340,10 @@ void commit_start(const char *job_id, BlockDriverState *bs,
         }
     }
 
+    if (bdrv_freeze_backing_chain(commit_top_bs, base, errp) < 0) {
+        goto fail;
+    }
+
     ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp);
     if (ret < 0) {
         goto fail;
-- 
2.11.0