From 4c355d53c6a5444b78b695f8bf106f1ffcba45e1 Mon Sep 17 00:00:00 2001 From: Zhi Yong Wu Date: Thu, 12 Apr 2012 14:00:57 +0200 Subject: block: add the support to drain throttled requests Signed-off-by: Zhi Yong Wu [ Iterate until all block devices have processed all requests, add comments. - Paolo ] Signed-off-by: Paolo Bonzini Signed-off-by: Kevin Wolf --- block.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) (limited to 'block.c') diff --git a/block.c b/block.c index ee7d8f220f..a307fe177f 100644 --- a/block.c +++ b/block.c @@ -906,12 +906,31 @@ void bdrv_close_all(void) * * This function does not flush data to disk, use bdrv_flush_all() for that * after calling this function. + * + * Note that completion of an asynchronous I/O operation can trigger any + * number of other I/O operations on other devices---for example a coroutine + * can be arbitrarily complex and a constant flow of I/O can come until the + * coroutine is complete. Because of this, it is not possible to have a + * function to drain a single device's I/O queue. */ void bdrv_drain_all(void) { BlockDriverState *bs; + bool busy; - qemu_aio_flush(); + do { + busy = qemu_aio_wait(); + + /* FIXME: We do not have timer support here, so this is effectively + * a busy wait. + */ + QTAILQ_FOREACH(bs, &bdrv_states, list) { + if (!qemu_co_queue_empty(&bs->throttled_reqs)) { + qemu_co_queue_restart_all(&bs->throttled_reqs); + busy = true; + } + } + } while (busy); /* If requests are still pending there is a bug somewhere */ QTAILQ_FOREACH(bs, &bdrv_states, list) { -- cgit v1.2.3