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From f39d8d56b3cf31f293465bd912ae623ada8152c0 Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Tue, 7 Jan 2014 21:57:15 +0100
Subject: [PATCH 10/14] qcow2: Free only newly allocated clusters on error

RH-Author: Max Reitz <mreitz@redhat.com>
Message-id: <1389131839-12920-11-git-send-email-mreitz@redhat.com>
Patchwork-id: 56546
O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 10/14] qcow2: Free only newly allocated clusters on error
Bugzilla: 1033490
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

BZ: 1033490

In expand_zero_clusters_in_l1, a new cluster is only allocated if it was
not already preallocated. On error, such preallocated clusters should
not be freed, but only the newly allocated ones.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 320c70666687db4dd4df8165f9fe6960de782ca9)

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/qcow2-cluster.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/qcow2-cluster.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index bfdc83a..79c3ae0 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1552,6 +1552,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
             uint64_t l2_entry = be64_to_cpu(l2_table[j]);
             int64_t offset = l2_entry & L2E_OFFSET_MASK, cluster_index;
             int cluster_type = qcow2_get_cluster_type(l2_entry);
+            bool preallocated = offset != 0;
 
             if (cluster_type == QCOW2_CLUSTER_NORMAL) {
                 cluster_index = offset >> s->cluster_bits;
@@ -1577,8 +1578,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
                 continue;
             }
 
-            if (!offset) {
-                /* not preallocated */
+            if (!preallocated) {
                 if (!bs->backing_hd) {
                     /* not backed; therefore we can simply deallocate the
                      * cluster */
@@ -1596,16 +1596,20 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
 
             ret = qcow2_pre_write_overlap_check(bs, 0, offset, s->cluster_size);
             if (ret < 0) {
-                qcow2_free_clusters(bs, offset, s->cluster_size,
-                        QCOW2_DISCARD_ALWAYS);
+                if (!preallocated) {
+                    qcow2_free_clusters(bs, offset, s->cluster_size,
+                                        QCOW2_DISCARD_ALWAYS);
+                }
                 goto fail;
             }
 
             ret = bdrv_write_zeroes(bs->file, offset / BDRV_SECTOR_SIZE,
                                     s->cluster_sectors, 0);
             if (ret < 0) {
-                qcow2_free_clusters(bs, offset, s->cluster_size,
-                        QCOW2_DISCARD_ALWAYS);
+                if (!preallocated) {
+                    qcow2_free_clusters(bs, offset, s->cluster_size,
+                                        QCOW2_DISCARD_ALWAYS);
+                }
                 goto fail;
             }
 
-- 
1.7.1