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From 48ec01bf0d7ad38571741cf9aca816a0bfdddbe0 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 16:22:10 +0200
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Subject: [PATCH 16/42] qcow2: Calculate refcount block entry count
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Message-id: <1434212556-3927-17-git-send-email-mreitz@redhat.com>
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Patchwork-id: 66035
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O-Subject: [RHEL-7.2 qemu-kvm PATCH 16/42] qcow2: Calculate refcount block entry count
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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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BZ: 1129893
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The size of a refblock entry is (in theory) variable; calculate
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therefore the number of entries per refblock and the according bit shift
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(1 << x == entry count) when opening an image.
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 1d13d654666a7fd6d6a85a0ce9285dbf0d0444c2)
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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.c | 3 +++
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 block/qcow2.h | 2 ++
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 2 files changed, 5 insertions(+)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index be7e8e8..fae8b26 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -604,6 +604,9 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
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     s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
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     s->l2_size = 1 << s->l2_bits;
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+    /* 2^(s->refcount_order - 3) is the refcount width in bytes */
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+    s->refcount_block_bits = s->cluster_bits - (s->refcount_order - 3);
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+    s->refcount_block_size = 1 << s->refcount_block_bits;
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     bs->total_sectors = header.size / 512;
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     s->csize_shift = (62 - (s->cluster_bits - 8));
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     s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
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diff --git a/block/qcow2.h b/block/qcow2.h
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index 2138462..b65f629 100644
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--- a/block/qcow2.h
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+++ b/block/qcow2.h
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@@ -213,6 +213,8 @@ typedef struct BDRVQcowState {
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     int l2_size;
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     int l1_size;
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     int l1_vm_state_index;
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+    int refcount_block_bits;
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+    int refcount_block_size;
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     int csize_shift;
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     int csize_mask;
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     uint64_t cluster_offset_mask;
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-- 
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1.8.3.1
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