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From 48ec01bf0d7ad38571741cf9aca816a0bfdddbe0 Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Sat, 13 Jun 2015 16:22:10 +0200
Subject: [PATCH 16/42] qcow2: Calculate refcount block entry count

Message-id: <1434212556-3927-17-git-send-email-mreitz@redhat.com>
Patchwork-id: 66035
O-Subject: [RHEL-7.2 qemu-kvm PATCH 16/42] qcow2: Calculate refcount block entry count
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>

BZ: 1129893

The size of a refblock entry is (in theory) variable; calculate
therefore the number of entries per refblock and the according bit shift
(1 << x == entry count) when opening an image.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 1d13d654666a7fd6d6a85a0ce9285dbf0d0444c2)

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/qcow2.c | 3 +++
 block/qcow2.h | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/block/qcow2.c b/block/qcow2.c
index be7e8e8..fae8b26 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -604,6 +604,9 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
 
     s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
     s->l2_size = 1 << s->l2_bits;
+    /* 2^(s->refcount_order - 3) is the refcount width in bytes */
+    s->refcount_block_bits = s->cluster_bits - (s->refcount_order - 3);
+    s->refcount_block_size = 1 << s->refcount_block_bits;
     bs->total_sectors = header.size / 512;
     s->csize_shift = (62 - (s->cluster_bits - 8));
     s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
diff --git a/block/qcow2.h b/block/qcow2.h
index 2138462..b65f629 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -213,6 +213,8 @@ typedef struct BDRVQcowState {
     int l2_size;
     int l1_size;
     int l1_vm_state_index;
+    int refcount_block_bits;
+    int refcount_block_size;
     int csize_shift;
     int csize_mask;
     uint64_t cluster_offset_mask;
-- 
1.8.3.1