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From 2f11a1952881d9e2dcc8acb3549441dbd9ade1e3 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 14 Aug 2019 08:42:26 +0100
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Subject: [PATCH 03/10] virtio-blk: Increase in_flight for request restart BH
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20190814084229.6458-3-kwolf@redhat.com>
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Patchwork-id: 89967
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O-Subject: [RHEL-8.1.0 qemu-kvm PATCH 2/5] virtio-blk: Increase in_flight for request restart BH
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Bugzilla: 1716349
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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virtio_blk_dma_restart_bh() submits new requests, so in order to make
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sure that these requests are not started inside a drained section of the
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attached BlockBackend, we need to make sure that draining the
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BlockBackend waits for the BH to be executed.
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This BH is still questionable because its scheduled in the main thread
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instead of the configured iothread. Leave a FIXME comment for this.
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But with this fix, enabling the data plane at least waits for these
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requests (in bdrv_set_aio_context()) instead of changing the AioContext
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under their feet and making them run in the wrong thread, causing
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crashes and failures (e.g. due to missing locking).
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 680f200217748e0920b79ec1d524717c2f50935b)
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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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hw/block/virtio-blk.c | 4 ++++
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1 file changed, 4 insertions(+)
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diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
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index b1532e4..691ade4 100644
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--- a/hw/block/virtio-blk.c
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+++ b/hw/block/virtio-blk.c
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@@ -678,6 +678,7 @@ static void virtio_blk_dma_restart_bh(void *opaque)
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if (mrb.num_reqs) {
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virtio_blk_submit_multireq(s->blk, &mrb);
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}
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+ blk_dec_in_flight(s->conf.conf.blk);
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aio_context_release(blk_get_aio_context(s->conf.conf.blk));
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}
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@@ -691,8 +692,11 @@ static void virtio_blk_dma_restart_cb(void *opaque, int running,
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}
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if (!s->bh) {
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+ /* FIXME The data plane is not started yet, so these requests are
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+ * processed in the main thread. */
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s->bh = aio_bh_new(blk_get_aio_context(s->conf.conf.blk),
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virtio_blk_dma_restart_bh, s);
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+ blk_inc_in_flight(s->conf.conf.blk);
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qemu_bh_schedule(s->bh);
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}
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}
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--
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1.8.3.1
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