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block/io: Quiesce parents between drained_begin/end

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So far, bdrv_parent_drained_begin/end() was called for the duration of
the actual bdrv_drain() at the beginning of a drained section, but we
really should keep parents quiesced until the end of the drained
section.

This does not actually change behaviour at this point because the only
user of the .drained_begin/end BdrvChildRole callback is I/O throttling,
which already doesn't send any new requests after flushing its queue in
.drained_begin. The patch merely removes a trap for future users.

Reported-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2016-05-11 14:57:23 +02:00
parent c2066af051
commit bb9aaecaf1
1 changed files with 3 additions and 0 deletions
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block/io.c
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@ -2749,11 +2749,14 @@ void bdrv_drained_begin(BlockDriverState *bs)
if (!bs->quiesce_counter++) {
aio_disable_external(bdrv_get_aio_context(bs));
}
bdrv_parent_drained_begin(bs);
bdrv_drain(bs);
}
void bdrv_drained_end(BlockDriverState *bs)
{
bdrv_parent_drained_end(bs);
assert(bs->quiesce_counter > 0);
if (--bs->quiesce_counter > 0) {
return;