From d62dd4f2f0b7acca3177935fbad1f1253ac722ef Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 10 Oct 2018 20:21:43 +0100 Subject: [PATCH 17/49] block: Defer .bdrv_drain_begin callback to polling phase RH-Author: Kevin Wolf Message-id: <20181010202213.7372-5-kwolf@redhat.com> Patchwork-id: 82594 O-Subject: [RHEL-8 qemu-kvm PATCH 14/44] block: Defer .bdrv_drain_begin callback to polling phase Bugzilla: 1637976 RH-Acked-by: Max Reitz RH-Acked-by: John Snow RH-Acked-by: Thomas Huth We cannot allow aio_poll() in bdrv_drain_invoke(begin=true) until we're done with propagating the drain through the graph and are doing the single final BDRV_POLL_WHILE(). Just schedule the coroutine with the callback and increase bs->in_flight to make sure that the polling phase will wait for it. Signed-off-by: Kevin Wolf (cherry picked from commit 0109e7e6f83ae5166b81bbd9a4319d60be49985a) Signed-off-by: Kevin Wolf Signed-off-by: Danilo C. L. de Paula --- block/io.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/block/io.c b/block/io.c index 9c41ff9..23fe069 100644 --- a/block/io.c +++ b/block/io.c @@ -181,22 +181,40 @@ static void coroutine_fn bdrv_drain_invoke_entry(void *opaque) /* Set data->done before reading bs->wakeup. */ atomic_mb_set(&data->done, true); - bdrv_wakeup(bs); + bdrv_dec_in_flight(bs); + + if (data->begin) { + g_free(data); + } } /* Recursively call BlockDriver.bdrv_co_drain_begin/end callbacks */ static void bdrv_drain_invoke(BlockDriverState *bs, bool begin) { - BdrvCoDrainData data = { .bs = bs, .done = false, .begin = begin}; + BdrvCoDrainData *data; if (!bs->drv || (begin && !bs->drv->bdrv_co_drain_begin) || (!begin && !bs->drv->bdrv_co_drain_end)) { return; } - data.co = qemu_coroutine_create(bdrv_drain_invoke_entry, &data); - bdrv_coroutine_enter(bs, data.co); - BDRV_POLL_WHILE(bs, !data.done); + data = g_new(BdrvCoDrainData, 1); + *data = (BdrvCoDrainData) { + .bs = bs, + .done = false, + .begin = begin + }; + + /* Make sure the driver callback completes during the polling phase for + * drain_begin. */ + bdrv_inc_in_flight(bs); + data->co = qemu_coroutine_create(bdrv_drain_invoke_entry, data); + aio_co_schedule(bdrv_get_aio_context(bs), data->co); + + if (!begin) { + BDRV_POLL_WHILE(bs, !data->done); + g_free(data); + } } /* Returns true if BDRV_POLL_WHILE() should go into a blocking aio_poll() */ -- 1.8.3.1