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From 8be02a0613ef6aee7a95ab7dae3d0aa489b65249 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Tue, 1 Apr 2014 09:45:35 +0200
Subject: [PATCH 2/2] qcow2: link all L2 meta updates in preallocate()

RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: <1396345535-19829-1-git-send-email-stefanha@redhat.com>
Patchwork-id: 58320
O-Subject: [RHEL7 qemu-kvm PATCH] qcow2: link all L2 meta updates in preallocate()
Bugzilla: 1081393
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

BZ: 1081393
Upstream: not merged yet, http://article.gmane.org/gmane.comp.emulators.qemu/264904
BREW: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7282765

preallocate() only links the first QCowL2Meta's data clusters into the
L2 table and ignores any chained QCowL2Metas in the linked list.

Chains of QCowL2Meta structs are built up when contiguous clusters span
L2 tables.  Each QCowL2Meta describes one L2 table update.  This is a
rare case in preallocate() but can happen.

This patch fixes preallocate() by iterating over the whole list of
QCowL2Metas.  Compare with the qcow2_co_writev() function's
implementation, which is similar but also also handles request
dependencies.  preallocate() only performs one allocation at a time so
there can be no dependencies.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/qcow2.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/qcow2.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 66ed906..7398b16 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1509,7 +1509,9 @@ static int preallocate(BlockDriverState *bs)
             return ret;
         }
 
-        if (meta != NULL) {
+        while (meta) {
+            QCowL2Meta *next = meta->next;
+
             ret = qcow2_alloc_cluster_link_l2(bs, meta);
             if (ret < 0) {
                 qcow2_free_any_clusters(bs, meta->alloc_offset,
@@ -1520,6 +1522,9 @@ static int preallocate(BlockDriverState *bs)
             /* There are no dependent requests, but we need to remove our
              * request from the list of in-flight requests */
             QLIST_REMOVE(meta, next_in_flight);
+
+            g_free(meta);
+            meta = next;
         }
 
         /* TODO Preallocate data if requested */
-- 
1.7.1