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: Kevin Wolf <kwolf@redhat.com>

block/backup.c

diff --git a/block/backup.c b/block/backup.c
index 910ed76..916817d 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -300,13 +300,6 @@
     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 @@
         .abort                  = backup_abort,
         .clean                  = backup_clean,
     },
-    .attached_aio_context   = backup_attached_aio_context,
     .drain                  = backup_drain,
 };
 

block/mirror.c

diff --git a/block/mirror.c b/block/mirror.c
index ff15cfb..ec4bd9f 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1142,13 +1142,6 @@
     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 @@
         .complete               = mirror_complete,
     },
     .drained_poll           = mirror_drained_poll,
-    .attached_aio_context   = mirror_attached_aio_context,
     .drain                  = mirror_drain,
 };
 
@@ -1196,7 +1188,6 @@
         .complete               = mirror_complete,
     },
     .drained_poll           = mirror_drained_poll,
-    .attached_aio_context   = mirror_attached_aio_context,
     .drain                  = mirror_drain,
 };
 
@@ -1612,6 +1603,7 @@
          * 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

diff --git a/blockjob.c b/blockjob.c
index 730101d..24e6093 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -183,11 +183,44 @@
     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 @@
 
     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) {