block: Decouple throttling from BlockDriverState

This moves the throttling related part of the BDS life cycle management
to BlockBackend. The throttling group reference is now kept even when no
medium is inserted.

With this commit, throttling isn't disabled and then re-enabled any more
during graph reconfiguration. This fixes the temporary breakage of I/O
throttling when used with live snapshots or block jobs that manipulate
the graph.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 0 insertions, 34 deletions

diff --git a/block.c b/block.c
index b5c02c4654..98226fe073 100644
--- a/block.c
+++ b/block.c
@@ -38,7 +38,6 @@
 #include "qmp-commands.h"
 #include "qemu/timer.h"
 #include "qapi-event.h"
-#include "block/throttle-groups.h"
 #include "qemu/cutils.h"
 #include "qemu/id.h"
 
@@ -2121,11 +2120,6 @@ static void bdrv_close(BlockDriverState *bs)
 
     assert(!bs->job);
 
-    /* Disable I/O limits and drain all pending throttled requests */
-    if (bs->blk && blk_get_public(bs->blk)->throttle_state) {
-        blk_io_limits_disable(bs->blk);
-    }
-
     bdrv_drained_begin(bs); /* complete I/O */
     bdrv_flush(bs);
     bdrv_drain(bs); /* in case flush left pending I/O */
@@ -2254,26 +2248,6 @@ static void swap_feature_fields(BlockDriverState *bs_top,
     bdrv_move_feature_fields(&tmp, bs_top);
     bdrv_move_feature_fields(bs_top, bs_new);
     bdrv_move_feature_fields(bs_new, &tmp);
-
-    assert(!bs_new->blk);
-    if (bs_top->blk && blk_get_public(bs_top->blk)->throttle_state) {
-        /*
-         * FIXME Need to break I/O throttling with graph manipulations
-         * temporarily because of conflicting invariants (3. will go away when
-         * throttling is fully converted to work on BlockBackends):
-         *
-         * 1. Every BlockBackend has a single root BDS
-         * 2. I/O throttling functions require an attached BlockBackend
-         * 3. We need to first enable throttling on the new BDS and then
-         *    disable it on the old one (because of throttle group refcounts)
-         */
-#if 0
-        bdrv_io_limits_enable(bs_new, throttle_group_get_name(bs_top));
-        bdrv_io_limits_disable(bs_top);
-#else
-        abort();
-#endif
-    }
 }
 
 /*
@@ -3674,10 +3648,6 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
         baf->detach_aio_context(baf->opaque);
     }
 
-    if (bs->blk && blk_get_public(bs->blk)->throttle_state) {
-        throttle_timers_detach_aio_context(
-            &blk_get_public(bs->blk)->throttle_timers);
-    }
     if (bs->drv->bdrv_detach_aio_context) {
         bs->drv->bdrv_detach_aio_context(bs);
     }
@@ -3711,10 +3681,6 @@ 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->blk && blk_get_public(bs->blk)->throttle_state) {
-        throttle_timers_attach_aio_context(
-            &blk_get_public(bs->blk)->throttle_timers, new_context);
-    }
 
     QLIST_FOREACH(ban, &bs->aio_notifiers, list) {
         ban->attached_aio_context(new_context, ban->opaque);