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