throttle: add throttle_detach/attach_aio_context()

Block I/O throttling uses timers and currently always adds them to the
main loop.  Throttling will break if bdrv_set_aio_context() is used to
move a BlockDriverState to a different AioContext.

This patch adds throttle_detach/attach_aio_context() interfaces so the
throttling timers and uses them to move timers to the new AioContext.
Note that bdrv_set_aio_context() already drains all requests so we're
sure no throttled requests are pending.

The test cases need to be updated since the throttle_init() interface
has changed.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/block.c b/block.c
index 1fd38159e2..17f763db79 100644
--- a/block.c
+++ b/block.c
@@ -179,6 +179,7 @@ void bdrv_io_limits_enable(BlockDriverState *bs)
 {
     assert(!bs->io_limits_enabled);
     throttle_init(&bs->throttle_state,
+                  bdrv_get_aio_context(bs),
                   QEMU_CLOCK_VIRTUAL,
                   bdrv_throttle_read_timer_cb,
                   bdrv_throttle_write_timer_cb,
@@ -5671,6 +5672,9 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
         return;
     }
 
+    if (bs->io_limits_enabled) {
+        throttle_detach_aio_context(&bs->throttle_state);
+    }
     if (bs->drv->bdrv_detach_aio_context) {
         bs->drv->bdrv_detach_aio_context(bs);
     }
@@ -5702,6 +5706,9 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
     if (bs->drv->bdrv_attach_aio_context) {
         bs->drv->bdrv_attach_aio_context(bs, new_context);
     }
+    if (bs->io_limits_enabled) {
+        throttle_attach_aio_context(&bs->throttle_state, new_context);
+    }
 }
 
 void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)