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From 1ae5408c46e940c7a993ba59c7e31163d78dd81a Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Sat, 13 Jun 2015 16:22:36 +0200
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Subject: [PATCH 42/42] qcow2: Flush pending discards before allocating cluster
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Message-id: <1434212556-3927-43-git-send-email-mreitz@redhat.com>
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Patchwork-id: 66061
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O-Subject: [RHEL-7.2 qemu-kvm PATCH 42/42] qcow2: Flush pending discards before allocating cluster
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Bugzilla: 1129893
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Kevin Wolf <kwolf@redhat.com>
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BZ: 1129893
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Before a freed cluster can be reused, pending discards for this cluster
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must be processed.
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The original assumption was that this was not a problem because discards
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are only cached during discard/write zeroes operations, which are
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synchronous so that no concurrent write requests can cause cluster
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allocations.
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However, the discard/write zeroes operation itself can allocate a new L2
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table (and it has to in order to put zero flags there), so make sure we
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can cope with the situation.
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This fixes https://bugs.launchpad.net/bugs/1349972.
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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(cherry picked from commit ecbda7a22576591a84f44de1be0150faf6001f1c)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block/qcow2-refcount.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
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index cee5b1f..848fd31 100644
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--- a/block/qcow2-refcount.c
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+++ b/block/qcow2-refcount.c
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@@ -663,6 +663,11 @@ static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size)
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uint64_t i, nb_clusters;
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int refcount;
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+ /* We can't allocate clusters if they may still be queued for discard. */
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+ if (s->cache_discards) {
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+ qcow2_process_discards(bs, 0);
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+ }
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+
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nb_clusters = size_to_clusters(s, size);
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retry:
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for(i = 0; i < nb_clusters; i++) {
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--
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1.8.3.1
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