On Fri, Feb 24, 2012 at 05:25:08PM +0800, Zhi Yong Wu wrote: > 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?
Both are useful: /** * Complete all pending requests for a block device */ void bdrv_drain(BlockDriverState *bs); /** * Complete pending requests for all block devices */ void bdrv_drain_all(void); Stefan