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From 01a2d73852aa716e9e57ca9726f967f5e801d6f5 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Tue, 5 Nov 2013 14:09:18 +0100
Subject: [PATCH 65/87] block: Disable BDRV_O_COPY_ON_READ for the backing file

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1383660558-32096-25-git-send-email-kwolf@redhat.com>
Patchwork-id: 55403
O-Subject: [RHEL-7.0 qemu-kvm PATCH 24/24] block: Disable BDRV_O_COPY_ON_READ for the backing file
Bugzilla: 978402
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

From: Thibaut LAURENT <thibaut.laurent@gmail.com>

Since commit 0ebd24e0a203cf2852c310b59fbe050190dc6c8c,
bdrv_open_common will throw an error when trying to open a file
read-only with the BDRV_O_COPY_ON_READ flag set.
Although BDRV_O_RDWR is unset for the backing files,
BDRV_O_COPY_ON_READ is still passed on if copy-on-read was requested
for the drive. Let's unset this flag too before opening the backing
file, or bdrv_open_common will fail.

Signed-off-by: Thibaut LAURENT <thibaut.laurent@gmail.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 87a5debd3161d24a7d4c685e3c0d8765b5d92a74)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/block.c b/block.c
index 01c11ee..beeb600 100644
--- a/block.c
+++ b/block.c
@@ -968,7 +968,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
     }
 
     /* backing files always opened read-only */
-    back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT);
+    back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT |
+                                    BDRV_O_COPY_ON_READ);
 
     ret = bdrv_open(bs->backing_hd,
                     *backing_filename ? backing_filename : NULL, options,
-- 
1.7.1