block: move drain outside of quorum_del_child()

The quorum_del_child() callback runs under the graph lock, so it is
not allowed to drain. It is only called as the .bdrv_del_child()
callback, which is only called in the bdrv_del_child() function, which
also runs under the graph lock.

The bdrv_del_child() function is called by qmp_x_blockdev_change().
A drained section was already introduced there by commit "block: move
drain out of quorum_add_child()".

This finally finishes moving out the drain to places that are not
under the graph lock started in "block: move draining out of
bdrv_change_aio_context() and mark GRAPH_RDLOCK".

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20250530151125.955508-17-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block.c b/block.c
index 15a8ccb822d45697324d2c35187efb610281ec92..bfd4340b24de465e5e913d513a1539531359f593 100644 (file)
--- a/block.c
+++ b/block.c
@@ -8276,6 +8276,8 @@ void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
 /*
  * Hot remove a BDS's child. Used in combination with bdrv_add_child, so the
  * user can take a child offline when it is broken and take a new child online.
+ *
+ * All block nodes must be drained.
  */
 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
 {

diff --git a/block/quorum.c b/block/quorum.c
index 81407a38eea4eeb049670f3b1d15d37c5cdbeb89..cc3bc5f4e7d605c800eaeaf2ae57ccfacb285f31 100644 (file)
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -1147,9 +1147,7 @@ quorum_del_child(BlockDriverState *bs, BdrvChild *child, Error **errp)
             (s->num_children - i - 1) * sizeof(BdrvChild *));
     s->children = g_renew(BdrvChild *, s->children, --s->num_children);
 
-    bdrv_drain_all_begin();
     bdrv_unref_child(bs, child);
-    bdrv_drain_all_end();
 
     quorum_refresh_flags(bs);
 }

diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index f9e742f81219cb398c54825c8c143dc2722ca8b8..925a3e73530094c5b08e92c407f8e8f537b8a2b7 100644 (file)
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -406,6 +406,13 @@ struct BlockDriver {
     void GRAPH_WRLOCK_PTR (*bdrv_add_child)(
         BlockDriverState *parent, BlockDriverState *child, Error **errp);
 
+    /**
+     * Hot remove a BDS's child. Used in combination with bdrv_add_child, so the
+     * user can take a child offline when it is broken and take a new child
+     * online.
+     *
+     * All block nodes must be drained.
+     */
     void GRAPH_WRLOCK_PTR (*bdrv_del_child)(
         BlockDriverState *parent, BdrvChild *child, Error **errp);