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block: Make sure throttled BDSes always have a BB

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It was already true in principle that a throttled BDS always has a BB
attached, except that the order of operations while attaching or
detaching a BDS to/from a BB wasn't careful enough.

This commit breaks graph manipulations while I/O throttling is enabled.
It would have been possible to keep things working with some temporary
hacks, but quite cumbersome, so it's not worth the hassle. We'll fix
things again in a minute.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2016-03-21 10:49:51 +01:00
parent 8ec4fe0a4b
commit a5614993d7
4 changed files with 27 additions and 5 deletions
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14
block.c
View File

@ -2259,8 +2259,22 @@ static void swap_feature_fields(BlockDriverState *bs_top,
assert(!bs_new->throttle_state);
if (bs_top->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
}
}

3
block/block-backend.c
View File

@ -420,6 +420,9 @@ void blk_remove_bs(BlockBackend *blk)
notifier_list_notify(&blk->remove_bs_notifiers, blk);
blk_update_root_state(blk);
if (blk->root->bs->throttle_state) {
bdrv_io_limits_disable(blk->root->bs);
}
blk->root->bs->blk = NULL;
bdrv_root_unref_child(blk->root);

4
blockdev.c
View File

@ -2570,8 +2570,6 @@ void qmp_blockdev_change_medium(const char *device, const char *filename,
goto fail;
}
blk_apply_root_state(blk, medium_bs);
bdrv_add_key(medium_bs, NULL, &err);
if (err) {
error_propagate(errp, err);
@ -2596,6 +2594,8 @@ void qmp_blockdev_change_medium(const char *device, const char *filename,
goto fail;
}
blk_apply_root_state(blk, medium_bs);
qmp_blockdev_close_tray(device, errp);
fail:

11
tests/test-throttle.c
View File

@ -574,11 +574,16 @@ static void test_accounting(void)
static void test_groups(void)
{
ThrottleConfig cfg1, cfg2;
BlockBackend *blk1, *blk2, *blk3;
BlockDriverState *bdrv1, *bdrv2, *bdrv3;
bdrv1 = bdrv_new();
bdrv2 = bdrv_new();
bdrv3 = bdrv_new();
blk1 = blk_new_with_bs(&error_abort);
blk2 = blk_new_with_bs(&error_abort);
blk3 = blk_new_with_bs(&error_abort);
bdrv1 = blk_bs(blk1);
bdrv2 = blk_bs(blk2);
bdrv3 = blk_bs(blk3);
g_assert(bdrv1->throttle_state == NULL);
g_assert(bdrv2->throttle_state == NULL);