Blame SOURCES/kvm-block-Use-normal-drain-for-bdrv_set_aio_context.patch

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From cf6bc30f7b525f0d646db62e49cbf02f3f28a1f2 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 08:42:29 +0100
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Subject: [PATCH 06/10] block: Use normal drain for bdrv_set_aio_context()
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20190814084229.6458-6-kwolf@redhat.com>
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Patchwork-id: 89968
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O-Subject: [RHEL-8.1.0 qemu-kvm PATCH 5/5] block: Use normal drain for bdrv_set_aio_context()
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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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Now that bdrv_set_aio_context() works inside drained sections, it can
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also use the real drain function instead of open coding something
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similar.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit d70d595429ecd9ac4917e53453dd8979db8e5ffd)
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RHEL: This conflicts because we didn't backport the removal of the
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polling loop. The conflict is resolved so that the polling loop moves to
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above the drain and any requests a BH would spawn would still be
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correctly drained afterwards. The changed order alone would have
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compensated for the virtio-blk bug and it potentially compensates for
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other bugs, too (we know of bugs in the NBD client at least), so leaving
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the polling loop in, with the new ordering, feels like the safe way for
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a downstream backport.
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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.c | 11 +++++------
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 1 file changed, 5 insertions(+), 6 deletions(-)
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diff --git a/block.c b/block.c
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index 9d9b8a9..8f3ceea 100644
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--- a/block.c
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+++ b/block.c
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@@ -4989,18 +4989,18 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
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     bs->walking_aio_notifiers = false;
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 }
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+/* The caller must own the AioContext lock for the old AioContext of bs, but it
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+ * must not own the AioContext lock for new_context (unless new_context is
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+ * the same as the current context of bs). */
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 void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
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 {
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     AioContext *ctx = bdrv_get_aio_context(bs);
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-    aio_disable_external(ctx);
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-    bdrv_parent_drained_begin(bs, NULL, false);
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-    bdrv_drain(bs); /* ensure there are no in-flight requests */
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-
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     while (aio_poll(ctx, false)) {
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         /* wait for all bottom halves to execute */
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     }
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+    bdrv_drained_begin(bs);
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     bdrv_detach_aio_context(bs);
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     /* This function executes in the old AioContext so acquire the new one in
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@@ -5008,8 +5008,7 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
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      */
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     aio_context_acquire(new_context);
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     bdrv_attach_aio_context(bs, new_context);
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-    bdrv_parent_drained_end(bs, NULL, false);
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-    aio_enable_external(ctx);
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+    bdrv_drained_end(bs);
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     aio_context_release(new_context);
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 }
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-- 
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1.8.3.1
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