[PATCH 04/20] block.c: wrlock in bdrv_replace_child_noperm

[Emanuele Giuseppe Esposito <eesposit@redhat.com>]

Protect the main function where graph is modified.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 block.c                          | 6 ++++--
 include/block/block_int-common.h | 1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index d3e168408a..4ef537a9f2 100644
--- a/block.c
+++ b/block.c
@@ -1416,6 +1416,7 @@ static void bdrv_child_cb_attach(BdrvChild *child)
 
     assert_bdrv_graph_writable(bs);
     QLIST_INSERT_HEAD(&bs->children, child, next);
+
     if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) {
         /*
          * Here we handle filters and block/raw-format.c when it behave like
@@ -2829,24 +2830,25 @@ static void bdrv_replace_child_noperm(BdrvChild *child,
         assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
     }
 
+    bdrv_graph_wrlock();
     if (old_bs) {
         if (child->klass->detach) {
             child->klass->detach(child);
         }
-        assert_bdrv_graph_writable(old_bs);
+
         QLIST_REMOVE(child, next_parent);
     }
 
     child->bs = new_bs;
 
     if (new_bs) {
-        assert_bdrv_graph_writable(new_bs);
         QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
 
         if (child->klass->attach) {
             child->klass->attach(child);
         }
     }
+    bdrv_graph_wrunlock();
 
     /*
      * If the old child node was drained but the new one is not, allow
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 791dddfd7d..fd9f40a815 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -71,6 +71,7 @@ enum BdrvTrackedRequestType {
     BDRV_TRACKED_TRUNCATE,
 };
 
+
 /*
  * That is not quite good that BdrvTrackedRequest structure is public,
  * as block/io.c is very careful about incoming offset/bytes being
-- 
2.31.1