block: Remove aio_poll() in bdrv_drain_poll variants
bdrv_drain_poll_top_level() was buggy because it didn't release the
AioContext lock of the node to be drained before calling aio_poll().
This way, callbacks called by aio_poll() would possibly take the lock a
second time and run into a deadlock with a nested AIO_WAIT_WHILE() call.
However, it turns out that the aio_poll() call isn't actually needed any
more. It was introduced in commit 91af091f92
, which is effectively
reverted by this patch. The cases it was supposed to fix are now covered
by bdrv_drain_poll(), which waits for block jobs to reach a quiescent
state.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
parent
b5a7a05735
commit
4cf077b59f
@ -268,10 +268,6 @@ bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,
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static bool bdrv_drain_poll_top_level(BlockDriverState *bs, bool recursive,
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BdrvChild *ignore_parent)
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{
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/* Execute pending BHs first and check everything else only after the BHs
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* have executed. */
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while (aio_poll(bs->aio_context, false));
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return bdrv_drain_poll(bs, recursive, ignore_parent, false);
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}
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@ -511,10 +507,6 @@ static bool bdrv_drain_all_poll(void)
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BlockDriverState *bs = NULL;
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bool result = false;
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/* Execute pending BHs first (may modify the graph) and check everything
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* else only after the BHs have executed. */
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while (aio_poll(qemu_get_aio_context(), false));
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/* bdrv_drain_poll() can't make changes to the graph and we are holding the
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* main AioContext lock, so iterating bdrv_next_all_states() is safe. */
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while ((bs = bdrv_next_all_states(bs))) {
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