On Mon, Feb 20, 2012 at 12:50:30PM +0800, zwu.ker...@gmail.com wrote: > From: Zhi Yong Wu <wu...@linux.vnet.ibm.com> > > If one guest has multiple disks with enabling I/O throttling function > separately, when draining activities are done, some requests maybe are in the > throttled queue; So we need to restart them at first. > > Moreover, when only one disk need to be drained such as hotplug out, if > another disk still has some requests in its throttled queue, these request > should not be effected. > > Signed-off-by: Zhi Yong Wu <wu...@linux.vnet.ibm.com> > --- > block.c | 29 ++++++++++++++++++++++------- > block_int.h | 1 + > 2 files changed, 23 insertions(+), 7 deletions(-) > > diff --git a/block.c b/block.c > index ae297bb..f78df78 100644 > --- a/block.c > +++ b/block.c > @@ -853,25 +853,40 @@ void bdrv_close_all(void) > } > } > > -/* > - * Wait for pending requests to complete across all BlockDriverStates > - * > - * This function does not flush data to disk, use bdrv_flush_all() for that > - * after calling this function. > - */ > -void bdrv_drain_all(void) > +void bdrv_drain_request(BlockDriverState *throttled_bs) > { > BlockDriverState *bs; > > + QTAILQ_FOREACH(bs, &bdrv_states, list) { > + if (throttled_bs && throttled_bs != bs) { > + continue; > + } > + qemu_co_queue_restart_all(&bs->throttled_reqs); > + } > + > qemu_aio_flush();
Since I/O throttling is still enabled, the restarted requests could enqueue again if they exceed the limit. We could still hit the assert. If the semantics of bdrv_drain_request() are that no requests are pending when it returns then we need a loop here. BTW bdrv_drain() would be a shorter name for this function. Stefan