block: move ThrottleGroup membership to ThrottleGroupMember

This commit eliminates the 1:1 relationship between BlockBackend and
throttle group state.  Users will be able to create multiple throttle
nodes, each with its own throttle group state, in the future.  The
throttle group state cannot be per-BlockBackend anymore, it must be
per-throttle node. This is done by gathering ThrottleGroup membership
details from BlockBackendPublic into ThrottleGroupMember and refactoring
existing code to use the structure.

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>

1 files changed, 32 insertions, 7 deletions

diff --git a/include/block/throttle-groups.h b/include/block/throttle-groups.h
index d983d34074..1a6bcdae74 100644
--- a/include/block/throttle-groups.h
+++ b/include/block/throttle-groups.h
@@ -28,19 +28,44 @@
 #include "qemu/throttle.h"
 #include "block/block_int.h"
 
-const char *throttle_group_get_name(BlockBackend *blk);
+/* The ThrottleGroupMember structure indicates membership in a ThrottleGroup
+ * and holds related data.
+ */
+
+typedef struct ThrottleGroupMember {
+    /* throttled_reqs_lock protects the CoQueues for throttled requests.  */
+    CoMutex      throttled_reqs_lock;
+    CoQueue      throttled_reqs[2];
+
+    /* Nonzero if the I/O limits are currently being ignored; generally
+     * it is zero.  Accessed with atomic operations.
+     */
+    unsigned int io_limits_disabled;
+
+    /* The following fields are protected by the ThrottleGroup lock.
+     * See the ThrottleGroup documentation for details.
+     * throttle_state tells us if I/O limits are configured. */
+    ThrottleState *throttle_state;
+    ThrottleTimers throttle_timers;
+    unsigned       pending_reqs[2];
+    QLIST_ENTRY(ThrottleGroupMember) round_robin;
+
+} ThrottleGroupMember;
+
+const char *throttle_group_get_name(ThrottleGroupMember *tgm);
 
 ThrottleState *throttle_group_incref(const char *name);
 void throttle_group_unref(ThrottleState *ts);
 
-void throttle_group_config(BlockBackend *blk, ThrottleConfig *cfg);
-void throttle_group_get_config(BlockBackend *blk, ThrottleConfig *cfg);
+void throttle_group_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg);
+void throttle_group_get_config(ThrottleGroupMember *tgm, ThrottleConfig *cfg);
 
-void throttle_group_register_blk(BlockBackend *blk, const char *groupname);
-void throttle_group_unregister_blk(BlockBackend *blk);
-void throttle_group_restart_blk(BlockBackend *blk);
+void throttle_group_register_tgm(ThrottleGroupMember *tgm,
+                                const char *groupname);
+void throttle_group_unregister_tgm(ThrottleGroupMember *tgm);
+void throttle_group_restart_tgm(ThrottleGroupMember *tgm);
 
-void coroutine_fn throttle_group_co_io_limits_intercept(BlockBackend *blk,
+void coroutine_fn throttle_group_co_io_limits_intercept(ThrottleGroupMember *tgm,
                                                         unsigned int bytes,
                                                         bool is_write);