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From c1a149658ffb385f55e8bb06f06b6d195b91fd1b Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Mon, 9 Sep 2013 14:28:03 +0200
Subject: [PATCH 12/38] block: Always enable discard on the protocol level

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1378736903-18489-13-git-send-email-kwolf@redhat.com>
Patchwork-id: 54196
O-Subject: [RHEL-7.0 qemu-kvm PATCH 12/32] block: Always enable discard on the protocol level
Bugzilla: 1005818
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

Bugzilla: 1005818

Turning on discard options in qcow2 doesn't help a lot when the discard
requests that it issues are thrown away by the raw-posix layer. This
patch always enables discard functionality on the protocol level so that
it's the image format's responsibility to send (or not) discard
requests. Requests sent by the guest will be allowed or ignored by the
top level BlockDriverState, which depends on the discard=... option like
before.

In particular, this means that even without specifying options, the
qcow2 default of discarding deleted snapshots actually takes effect now,
both for qemu and qemu-img.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 50b05b6f2e24296b4d739a638e1e7427767ed7cd)

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

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

diff --git a/block.c b/block.c
index 2584ec7..20820fa 100644
--- a/block.c
+++ b/block.c
@@ -1055,7 +1055,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
     extract_subqdict(options, &file_options, "file.");
 
     ret = bdrv_file_open(&file, filename, file_options,
-                         bdrv_open_flags(bs, flags));
+                         bdrv_open_flags(bs, flags | BDRV_O_UNMAP));
     if (ret < 0) {
         goto fail;
     }
-- 
1.7.1