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block: Make bdrv_drain() use bdrv_drained_begin/end()

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Until now, bdrv_drained_begin() used bdrv_drain() internally to drain
the queue. This is kind of backwards and caused quiescing code to be
duplicated because bdrv_drained_begin() had to ensure that no new
requests come in even after bdrv_drain() returns, whereas bdrv_drain()
had to have them because it could be called from other places.

Instead move the bdrv_drain() code to bdrv_drained_begin() and make
bdrv_drain() a simple wrapper around bdrv_drained_begin/end().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Kevin Wolf 2016-05-23 16:08:55 +02:00
parent e9740bc6d4
commit 6820643fdb
1 changed files with 33 additions and 36 deletions
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69
block/io.c
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@ -225,6 +225,34 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs)
assert(data.done);
}
void bdrv_drained_begin(BlockDriverState *bs)
{
if (!bs->quiesce_counter++) {
aio_disable_external(bdrv_get_aio_context(bs));
bdrv_parent_drained_begin(bs);
}
bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
if (qemu_in_coroutine()) {
bdrv_co_yield_to_drain(bs);
} else {
bdrv_drain_poll(bs);
}
bdrv_io_unplugged_end(bs);
}
void bdrv_drained_end(BlockDriverState *bs)
{
assert(bs->quiesce_counter > 0);
if (--bs->quiesce_counter > 0) {
return;
}
bdrv_parent_drained_end(bs);
aio_enable_external(bdrv_get_aio_context(bs));
}
/*
* Wait for pending requests to complete on a single BlockDriverState subtree,
* and suspend block driver's internal I/O until next request arrives.
@ -238,26 +266,15 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs)
*/
void coroutine_fn bdrv_co_drain(BlockDriverState *bs)
{
bdrv_parent_drained_begin(bs);
bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
bdrv_co_yield_to_drain(bs);
bdrv_io_unplugged_end(bs);
bdrv_parent_drained_end(bs);
assert(qemu_in_coroutine());
bdrv_drained_begin(bs);
bdrv_drained_end(bs);
}
void bdrv_drain(BlockDriverState *bs)
{
bdrv_parent_drained_begin(bs);
bdrv_io_unplugged_begin(bs);
bdrv_drain_recurse(bs);
if (qemu_in_coroutine()) {
bdrv_co_yield_to_drain(bs);
} else {
bdrv_drain_poll(bs);
}
bdrv_io_unplugged_end(bs);
bdrv_parent_drained_end(bs);
bdrv_drained_begin(bs);
bdrv_drained_end(bs);
}
/*
@ -2541,23 +2558,3 @@ void bdrv_io_unplugged_end(BlockDriverState *bs)
}
}
}
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;
}
aio_enable_external(bdrv_get_aio_context(bs));
}