From cb60b78e889e738f88e4c056d7312290869e4f1d Mon Sep 17 00:00:00 2001
From: Eric Blake <eblake@redhat.com>
Date: Wed, 20 Aug 2014 16:40:14 +0200
Subject: [PATCH 7/7] mirror: Fix qiov size for short requests

Message-id: <1408552814-23031-8-git-send-email-eblake@redhat.com>
Patchwork-id: 60650
O-Subject: [qemu-kvm-rhev 7.0.z PATCH 7/7] mirror: Fix qiov size for short requests
Bugzilla: 1132806
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

From: Kevin Wolf <kwolf@redhat.com>

When mirroring an image of a size that is not a multiple of the
mirror job granularity, the last request would have the right nb_sectors
argument, but a qiov that is rounded up to the next multiple of the
granularity. Don't do this.

This fixes a segfault that is caused by raw-posix being confused by this
and allocating a buffer with request length, but operating on it with
qiov length.

[s/Driver/Drive/ in qemu-iotests 041 as suggested by Eric
--Stefan]

Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 5a0f6fd5c84573387056e0464a7fc0c6fb70b2dc)

Conflicts:
	tests/qemu-iotests/041.out - context with fewer tests run downstream

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/mirror.c             |    4 +++-
 tests/qemu-iotests/041     |    5 +++++
 tests/qemu-iotests/041.out |    4 ++--
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index cdc0268..b7cf4ab 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -243,9 +243,11 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob *s)
     next_sector = sector_num;
     while (nb_chunks-- > 0) {
         MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free);
+        size_t remaining = (nb_sectors * BDRV_SECTOR_SIZE) - op->qiov.size;
+
         QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next);
         s->buf_free_count--;
-        qemu_iovec_add(&op->qiov, buf, s->granularity);
+        qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining));
 
         /* Advance the HBitmapIter in parallel, so that we do not examine
          * the same sector twice.
diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 912e499..b654081 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -270,6 +270,11 @@ class TestSingleDriveZeroLength(TestSingleDrive):
     test_small_buffer2 = None
     test_large_cluster = None
 
+class TestSingleDriveUnalignedLength(TestSingleDrive):
+    image_len = 1025 * 1024
+    test_small_buffer2 = None
+    test_large_cluster = None
+
 class TestMirrorNoBacking(ImageMirroringTestCase):
     image_len = 2 * 1024 * 1024 # MB
 
diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
index cfa5c0d..802ffaa 100644
--- a/tests/qemu-iotests/041.out
+++ b/tests/qemu-iotests/041.out
@@ -1,5 +1,5 @@
-...................................
+...........................................
 ----------------------------------------------------------------------
-Ran 35 tests
+Ran 43 tests
 
 OK
-- 
1.7.1