block: Freeze the backing chain for the duration of the commit job
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/commit.c b/block/commit.c
index 3b46ca7..ba60fef 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -39,6 +39,7 @@
BlockDriverState *base_bs;
BlockdevOnError on_error;
bool base_read_only;
+ bool chain_frozen;
char *backing_file_str;
} CommitBlockJob;
@@ -68,6 +69,9 @@
{
CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
+ bdrv_unfreeze_backing_chain(s->commit_top_bs, s->base_bs);
+ s->chain_frozen = false;
+
/* Remove base node parent that still uses BLK_PERM_WRITE/RESIZE before
* the normal backing chain can be restored. */
blk_unref(s->base);
@@ -84,6 +88,10 @@
CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
BlockDriverState *top_bs = blk_bs(s->top);
+ if (s->chain_frozen) {
+ 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);
@@ -330,6 +338,11 @@
}
}
+ if (bdrv_freeze_backing_chain(commit_top_bs, base, errp) < 0) {
+ goto fail;
+ }
+ s->chain_frozen = true;
+
ret = block_job_add_bdrv(&s->common, "base", base, 0, BLK_PERM_ALL, errp);
if (ret < 0) {
goto fail;
@@ -362,6 +375,9 @@
return;
fail:
+ if (s->chain_frozen) {
+ bdrv_unfreeze_backing_chain(commit_top_bs, base);
+ }
if (s->base) {
blk_unref(s->base);
}