block: add aio_context field in ThrottleGroupMember

timer_cb() needs to know about the current Aio context of the throttle
request that is woken up. In order to make ThrottleGroupMember backend
agnostic, this information is stored in an aio_context field instead of
accessing it from BlockBackend.

Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 30 insertions, 23 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index 3dacd7eca7..b4acd0f2ae 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1747,18 +1747,14 @@ static AioContext *blk_aiocb_get_aio_context(BlockAIOCB *acb)
 void blk_set_aio_context(BlockBackend *blk, AioContext *new_context)
 {
     BlockDriverState *bs = blk_bs(blk);
-    ThrottleTimers *tt;
+    ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
 
     if (bs) {
-        if (blk->public.throttle_group_member.throttle_state) {
-            tt = &blk->public.throttle_group_member.throttle_timers;
-            throttle_timers_detach_aio_context(tt);
+        if (tgm->throttle_state) {
+            throttle_group_detach_aio_context(tgm);
+            throttle_group_attach_aio_context(tgm, new_context);
         }
         bdrv_set_aio_context(bs, new_context);
-        if (blk->public.throttle_group_member.throttle_state) {
-            tt = &blk->public.throttle_group_member.throttle_timers;
-            throttle_timers_attach_aio_context(tt, new_context);
-        }
     }
 }
 
@@ -1991,7 +1987,8 @@ void blk_io_limits_disable(BlockBackend *blk)
 void blk_io_limits_enable(BlockBackend *blk, const char *group)
 {
     assert(!blk->public.throttle_group_member.throttle_state);
-    throttle_group_register_tgm(&blk->public.throttle_group_member, group);
+    throttle_group_register_tgm(&blk->public.throttle_group_member,
+                                group, blk_get_aio_context(blk));
 }
 
 void blk_io_limits_update_group(BlockBackend *blk, const char *group)
diff --git a/block/throttle-groups.c b/block/throttle-groups.c
index c8ed16ddf8..3b07b25f39 100644
--- a/block/throttle-groups.c
+++ b/block/throttle-groups.c
@@ -391,9 +391,6 @@ static void coroutine_fn throttle_group_restart_queue_entry(void *opaque)
 
 static void throttle_group_restart_queue(ThrottleGroupMember *tgm, bool is_write)
 {
-    BlockBackendPublic *blkp = container_of(tgm, BlockBackendPublic,
-            throttle_group_member);
-    BlockBackend *blk = blk_by_public(blkp);
     Coroutine *co;
     RestartData rd = {
         .tgm = tgm,
@@ -401,7 +398,7 @@ static void throttle_group_restart_queue(ThrottleGroupMember *tgm, bool is_write
     };
 
     co = qemu_coroutine_create(throttle_group_restart_queue_entry, &rd);
-    aio_co_enter(blk_get_aio_context(blk), co);
+    aio_co_enter(tgm->aio_context, co);
 }
 
 void throttle_group_restart_tgm(ThrottleGroupMember *tgm)
@@ -449,13 +446,11 @@ void throttle_group_get_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg)
 /* ThrottleTimers callback. This wakes up a request that was waiting
  * because it had been throttled.
  *
- * @blk:       the BlockBackend whose request had been throttled
+ * @tgm:       the ThrottleGroupMember whose request had been throttled
  * @is_write:  the type of operation (read/write)
  */
-static void timer_cb(BlockBackend *blk, bool is_write)
+static void timer_cb(ThrottleGroupMember *tgm, bool is_write)
 {
-    BlockBackendPublic *blkp = blk_get_public(blk);
-    ThrottleGroupMember *tgm = &blkp->throttle_group_member;
     ThrottleState *ts = tgm->throttle_state;
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
 
@@ -484,18 +479,18 @@ static void write_timer_cb(void *opaque)
  *
  * @tgm:       the ThrottleGroupMember to insert
  * @groupname: the name of the group
+ * @ctx:       the AioContext to use
  */
 void throttle_group_register_tgm(ThrottleGroupMember *tgm,
-                                 const char *groupname)
+                                 const char *groupname,
+                                 AioContext *ctx)
 {
     int i;
-    BlockBackendPublic *blkp = container_of(tgm, BlockBackendPublic,
-            throttle_group_member);
-    BlockBackend *blk = blk_by_public(blkp);
     ThrottleState *ts = throttle_group_incref(groupname);
     ThrottleGroup *tg = container_of(ts, ThrottleGroup, ts);
 
     tgm->throttle_state = ts;
+    tgm->aio_context = ctx;
 
     qemu_mutex_lock(&tg->lock);
     /* If the ThrottleGroup is new set this ThrottleGroupMember as the token */
@@ -508,11 +503,11 @@ void throttle_group_register_tgm(ThrottleGroupMember *tgm,
     QLIST_INSERT_HEAD(&tg->head, tgm, round_robin);
 
     throttle_timers_init(&tgm->throttle_timers,
-                         blk_get_aio_context(blk),
+                         tgm->aio_context,
                          tg->clock_type,
                          read_timer_cb,
                          write_timer_cb,
-                         blk);
+                         tgm);
 
     qemu_mutex_unlock(&tg->lock);
 }
@@ -559,6 +554,21 @@ void throttle_group_unregister_tgm(ThrottleGroupMember *tgm)
     tgm->throttle_state = NULL;
 }
 
+void throttle_group_attach_aio_context(ThrottleGroupMember *tgm,
+                                       AioContext *new_context)
+{
+    ThrottleTimers *tt = &tgm->throttle_timers;
+    throttle_timers_attach_aio_context(tt, new_context);
+    tgm->aio_context = new_context;
+}
+
+void throttle_group_detach_aio_context(ThrottleGroupMember *tgm)
+{
+    ThrottleTimers *tt = &tgm->throttle_timers;
+    throttle_timers_detach_aio_context(tt);
+    tgm->aio_context = NULL;
+}
+
 static void throttle_groups_init(void)
 {
     qemu_mutex_init(&throttle_groups_lock);