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From 3ba36d5627afb6009c91c71ae8709d5dac2cc03d Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 10 Oct 2018 20:21:46 +0100
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Subject: [PATCH 20/49] block: Move bdrv_drain_all_begin() out of coroutine
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 context
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20181010202213.7372-8-kwolf@redhat.com>
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Patchwork-id: 82599
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O-Subject: [RHEL-8 qemu-kvm PATCH 17/44] block: Move bdrv_drain_all_begin() out of coroutine context
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Bugzilla: 1637976
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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Before we can introduce a single polling loop for all nodes in
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bdrv_drain_all_begin(), we must make sure to run it outside of coroutine
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context like we already do for bdrv_do_drained_begin().
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit c8ca33d06def97d909a8511377b82994ae4e5981)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 block/io.c | 22 +++++++++++++++++-----
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 1 file changed, 17 insertions(+), 5 deletions(-)
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diff --git a/block/io.c b/block/io.c
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index 23fe069..b58c91b 100644
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--- a/block/io.c
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+++ b/block/io.c
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@@ -263,11 +263,16 @@ static void bdrv_co_drain_bh_cb(void *opaque)
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     Coroutine *co = data->co;
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     BlockDriverState *bs = data->bs;
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-    bdrv_dec_in_flight(bs);
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-    if (data->begin) {
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-        bdrv_do_drained_begin(bs, data->recursive, data->parent, data->poll);
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+    if (bs) {
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+        bdrv_dec_in_flight(bs);
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+        if (data->begin) {
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+            bdrv_do_drained_begin(bs, data->recursive, data->parent, data->poll);
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+        } else {
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+            bdrv_do_drained_end(bs, data->recursive, data->parent);
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+        }
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     } else {
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-        bdrv_do_drained_end(bs, data->recursive, data->parent);
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+        assert(data->begin);
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+        bdrv_drain_all_begin();
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     }
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     data->done = true;
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@@ -293,7 +298,9 @@ static void coroutine_fn bdrv_co_yield_to_drain(BlockDriverState *bs,
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         .parent = parent,
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         .poll = poll,
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     };
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-    bdrv_inc_in_flight(bs);
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+    if (bs) {
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+        bdrv_inc_in_flight(bs);
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+    }
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     aio_bh_schedule_oneshot(bdrv_get_aio_context(bs),
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                             bdrv_co_drain_bh_cb, &data);
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@@ -463,6 +470,11 @@ void bdrv_drain_all_begin(void)
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     BlockDriverState *bs;
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     BdrvNextIterator it;
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+    if (qemu_in_coroutine()) {
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+        bdrv_co_yield_to_drain(NULL, true, false, NULL, true);
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+        return;
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+    }
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+
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     /* BDRV_POLL_WHILE() for a node can only be called from its own I/O thread
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      * or the main loop AioContext. We potentially use BDRV_POLL_WHILE() on
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      * nodes in several different AioContexts, so make sure we're in the main
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-- 
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1.8.3.1
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