blockjob: Propagate AioContext change to all job nodes

Block jobs require that all of the nodes the job is using are in the
same AioContext. Therefore all BdrvChild objects of the job propagate
.(can_)set_aio_context to all other job nodes, so that the switch is
checked and performed consistently even if both nodes are in different
subtrees.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/backup.c

@@ -300,13 +300,6 @@ static void backup_clean(Job *job)
     s->target = NULL;
 }
 
-static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context)
-{
-    BackupBlockJob *s = container_of(job, BackupBlockJob, common);
-
-    blk_set_aio_context(s->target, aio_context);
-}
-
 void backup_do_checkpoint(BlockJob *job, Error **errp)
 {
     BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
@@ -558,7 +551,6 @@ static const BlockJobDriver backup_job_driver = {
         .abort                  = backup_abort,
         .clean                  = backup_clean,
     },
-    .attached_aio_context   = backup_attached_aio_context,
     .drain                  = backup_drain,
 };
 

block/mirror.c

@@ -1142,13 +1142,6 @@ static bool mirror_drained_poll(BlockJob *job)
     return !!s->in_flight;
 }
 
-static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context)
-{
-    MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
-
-    blk_set_aio_context(s->target, new_context);
-}
-
 static void mirror_drain(BlockJob *job)
 {
     MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
@@ -1178,7 +1171,6 @@ static const BlockJobDriver mirror_job_driver = {
         .complete               = mirror_complete,
     },
     .drained_poll           = mirror_drained_poll,
-    .attached_aio_context   = mirror_attached_aio_context,
     .drain                  = mirror_drain,
 };
 
@@ -1196,7 +1188,6 @@ static const BlockJobDriver commit_active_job_driver = {
         .complete               = mirror_complete,
     },
     .drained_poll           = mirror_drained_poll,
-    .attached_aio_context   = mirror_attached_aio_context,
     .drain                  = mirror_drain,
 };
 
@@ -1612,6 +1603,7 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
          * ensure that. */
         blk_set_force_allow_inactivate(s->target);
     }
+    blk_set_allow_aio_context_change(s->target, true);
 
     s->replaces = g_strdup(replaces);
     s->on_source_error = on_source_error;

blockjob.c

@@ -183,11 +183,44 @@ static void child_job_drained_end(BdrvChild *c)
     job_resume(&job->job);
 }
 
+static bool child_job_can_set_aio_ctx(BdrvChild *c, AioContext *ctx,
+                                      GSList **ignore, Error **errp)
+{
+    BlockJob *job = c->opaque;
+    GSList *l;
+
+    for (l = job->nodes; l; l = l->next) {
+        BdrvChild *sibling = l->data;
+        if (!bdrv_child_can_set_aio_context(sibling, ctx, ignore, errp)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+static void child_job_set_aio_ctx(BdrvChild *c, AioContext *ctx,
+                                  GSList **ignore)
+{
+    BlockJob *job = c->opaque;
+    GSList *l;
+
+    for (l = job->nodes; l; l = l->next) {
+        BdrvChild *sibling = l->data;
+        if (g_slist_find(*ignore, sibling)) {
+            continue;
+        }
+        *ignore = g_slist_prepend(*ignore, sibling);
+        bdrv_set_aio_context_ignore(sibling->bs, ctx, ignore);
+    }
+}
+
 static const BdrvChildRole child_job = {
     .get_parent_desc    = child_job_get_parent_desc,
     .drained_begin      = child_job_drained_begin,
     .drained_poll       = child_job_drained_poll,
     .drained_end        = child_job_drained_end,
+    .can_set_aio_ctx    = child_job_can_set_aio_ctx,
+    .set_aio_ctx        = child_job_set_aio_ctx,
     .stay_at_node       = true,
 };
 
@@ -440,6 +473,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
 
     blk_add_aio_context_notifier(blk, block_job_attached_aio_context,
                                  block_job_detach_aio_context, job);
+    blk_set_allow_aio_context_change(blk, true);
 
     /* Only set speed when necessary to avoid NotSupported error */
     if (speed != 0) {