From 85bd20ed57493f867626fd7d5fa073b4476ae301 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Mon, 1 Jun 2015 18:09:17 +0200 Subject: [PATCH] qcow2: Set MIN_L2_CACHE_SIZE to 2 The L2 cache must cover at least two L2 tables, because during COW two L2 tables are accessed simultaneously. Reported-by: Alexander Graf Signed-off-by: Max Reitz Tested-by: Alexander Graf Reviewed-by: Alberto Garcia Signed-off-by: Alexander Graf --- block/qcow2.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/qcow2.h b/block/qcow2.h index 422b825..2f20949 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -62,7 +62,8 @@ #define MIN_CLUSTER_BITS 9 #define MAX_CLUSTER_BITS 21 -#define MIN_L2_CACHE_SIZE 1 /* cluster */ +/* Must be at least 2 to cover COW */ +#define MIN_L2_CACHE_SIZE 2 /* clusters */ /* Must be at least 4 to cover all cases of refcount table growth */ #define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */