1 files changed, 49 insertions, 27 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index 4f59664397..c0c7d56c8d 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -134,10 +134,9 @@ static void blk_root_drained_end(BdrvChild *child, int *drained_end_counter);
 static void blk_root_change_media(BdrvChild *child, bool load);
 static void blk_root_resize(BdrvChild *child);
 
-static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                     GSList **ignore, Error **errp);
-static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                 GSList **ignore);
+static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
+                                    GHashTable *visited, Transaction *tran,
+                                    Error **errp);
 
 static char *blk_root_get_parent_desc(BdrvChild *child)
 {
@@ -334,8 +333,7 @@ static const BdrvChildClass child_root = {
     .attach             = blk_root_attach,
     .detach             = blk_root_detach,
 
-    .can_set_aio_ctx    = blk_root_can_set_aio_ctx,
-    .set_aio_ctx        = blk_root_set_aio_ctx,
+    .change_aio_ctx     = blk_root_change_aio_ctx,
 
     .get_parent_aio_context = blk_root_get_parent_aio_context,
 };
@@ -1946,7 +1944,7 @@ bool blk_enable_write_cache(BlockBackend *blk)
 
 void blk_set_enable_write_cache(BlockBackend *blk, bool wce)
 {
-    GLOBAL_STATE_CODE();
+    IO_CODE();
     blk->enable_write_cache = wce;
 }
 
@@ -2149,8 +2147,11 @@ static int blk_do_set_aio_context(BlockBackend *blk, AioContext *new_context,
         bdrv_ref(bs);
 
         if (update_root_node) {
-            ret = bdrv_child_try_set_aio_context(bs, new_context, blk->root,
-                                                 errp);
+            /*
+             * update_root_node MUST be false for blk_root_set_aio_ctx_commit(),
+             * as we are already in the commit function of a transaction.
+             */
+            ret = bdrv_try_change_aio_context(bs, new_context, blk->root, errp);
             if (ret < 0) {
                 bdrv_unref(bs);
                 return ret;
@@ -2177,33 +2178,54 @@ int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
     return blk_do_set_aio_context(blk, new_context, true, errp);
 }
 
-static bool blk_root_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                     GSList **ignore, Error **errp)
+typedef struct BdrvStateBlkRootContext {
+    AioContext *new_ctx;
+    BlockBackend *blk;
+} BdrvStateBlkRootContext;
+
+static void blk_root_set_aio_ctx_commit(void *opaque)
+{
+    BdrvStateBlkRootContext *s = opaque;
+    BlockBackend *blk = s->blk;
+
+    blk_do_set_aio_context(blk, s->new_ctx, false, &error_abort);
+}
+
+static TransactionActionDrv set_blk_root_context = {
+    .commit = blk_root_set_aio_ctx_commit,
+    .clean = g_free,
+};
+
+static bool blk_root_change_aio_ctx(BdrvChild *child, AioContext *ctx,
+                                    GHashTable *visited, Transaction *tran,
+                                    Error **errp)
 {
     BlockBackend *blk = child->opaque;
+    BdrvStateBlkRootContext *s;
 
-    if (blk->allow_aio_context_change) {
-        return true;
+    if (!blk->allow_aio_context_change) {
+        /*
+         * Manually created BlockBackends (those with a name) that are not
+         * attached to anything can change their AioContext without updating
+         * their user; return an error for others.
+         */
+        if (!blk->name || blk->dev) {
+            /* TODO Add BB name/QOM path */
+            error_setg(errp, "Cannot change iothread of active block backend");
+            return false;
+        }
     }
 
-    /* Only manually created BlockBackends that are not attached to anything
-     * can change their AioContext without updating their user. */
-    if (!blk->name || blk->dev) {
-        /* TODO Add BB name/QOM path */
-        error_setg(errp, "Cannot change iothread of active block backend");
-        return false;
-    }
+    s = g_new(BdrvStateBlkRootContext, 1);
+    *s = (BdrvStateBlkRootContext) {
+        .new_ctx = ctx,
+        .blk = blk,
+    };
 
+    tran_add(tran, &set_blk_root_context, s);
     return true;
 }
 
-static void blk_root_set_aio_ctx(BdrvChild *child, AioContext *ctx,
-                                 GSList **ignore)
-{
-    BlockBackend *blk = child->opaque;
-    blk_do_set_aio_context(blk, ctx, false, &error_abort);
-}
-
 void blk_add_aio_context_notifier(BlockBackend *blk,
         void (*attached_aio_context)(AioContext *new_context, void *opaque),
         void (*detach_aio_context)(void *opaque), void *opaque)