On Fri, Feb 24, 2012 at 4:49 PM, Stefan Hajnoczi <stefa...@gmail.com> wrote: > 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. For this function's semantics, i have some concerns. Is it used to drain all requests of one single disk or all disks for one guest? which is more suitable?
> > Stefan -- Regards, Zhi Yong Wu