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[Qemu-block] [PATCH 3/4] qcow2: Discard preallocated zero clusters
From: |
Max Reitz |
Subject: |
[Qemu-block] [PATCH 3/4] qcow2: Discard preallocated zero clusters |
Date: |
Thu, 4 May 2017 01:11:19 +0200 |
In discard_single_l2(), we completely discard normal clusters instead of
simply turning them into preallocated zero clusters. That means we
should probably do the same with such preallocated zero clusters:
Discard them instead of keeping them allocated.
Reported-by: Eric Blake <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
block/qcow2-cluster.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index fb91fd8979..31077d8102 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1511,7 +1511,8 @@ static int discard_single_l2(BlockDriverState *bs,
uint64_t offset,
break;
case QCOW2_CLUSTER_ZERO:
- if (!full_discard) {
+ /* Preallocated zero clusters should be discarded in any case
*/
+ if (!full_discard && (old_l2_entry & L2E_OFFSET_MASK) == 0) {
continue;
}
break;
--
2.12.2