Blame SOURCES/kvm-mirror-Fix-qiov-size-for-short-requests.patch

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From cb60b78e889e738f88e4c056d7312290869e4f1d Mon Sep 17 00:00:00 2001
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From: Eric Blake <eblake@redhat.com>
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Date: Wed, 20 Aug 2014 16:40:14 +0200
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Subject: [PATCH 7/7] mirror: Fix qiov size for short requests
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Message-id: <1408552814-23031-8-git-send-email-eblake@redhat.com>
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Patchwork-id: 60650
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O-Subject: [qemu-kvm-rhev 7.0.z PATCH 7/7] mirror: Fix qiov size for short requests
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Bugzilla: 1132806
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Kevin Wolf <kwolf@redhat.com>
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When mirroring an image of a size that is not a multiple of the
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mirror job granularity, the last request would have the right nb_sectors
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argument, but a qiov that is rounded up to the next multiple of the
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granularity. Don't do this.
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This fixes a segfault that is caused by raw-posix being confused by this
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and allocating a buffer with request length, but operating on it with
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qiov length.
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[s/Driver/Drive/ in qemu-iotests 041 as suggested by Eric
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--Stefan]
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Reported-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Tested-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 5a0f6fd5c84573387056e0464a7fc0c6fb70b2dc)
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Conflicts:
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	tests/qemu-iotests/041.out - context with fewer tests run downstream
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Signed-off-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/mirror.c             |    4 +++-
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 tests/qemu-iotests/041     |    5 +++++
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 tests/qemu-iotests/041.out |    4 ++--
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 3 files changed, 10 insertions(+), 3 deletions(-)
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diff --git a/block/mirror.c b/block/mirror.c
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index cdc0268..b7cf4ab 100644
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--- a/block/mirror.c
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+++ b/block/mirror.c
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@@ -243,9 +243,11 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob *s)
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     next_sector = sector_num;
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     while (nb_chunks-- > 0) {
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         MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free);
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+        size_t remaining = (nb_sectors * BDRV_SECTOR_SIZE) - op->qiov.size;
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+
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         QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next);
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         s->buf_free_count--;
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-        qemu_iovec_add(&op->qiov, buf, s->granularity);
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+        qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining));
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         /* Advance the HBitmapIter in parallel, so that we do not examine
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          * the same sector twice.
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diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
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index 912e499..b654081 100755
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--- a/tests/qemu-iotests/041
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+++ b/tests/qemu-iotests/041
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@@ -270,6 +270,11 @@ class TestSingleDriveZeroLength(TestSingleDrive):
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     test_small_buffer2 = None
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     test_large_cluster = None
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+class TestSingleDriveUnalignedLength(TestSingleDrive):
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+    image_len = 1025 * 1024
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+    test_small_buffer2 = None
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+    test_large_cluster = None
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+
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 class TestMirrorNoBacking(ImageMirroringTestCase):
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     image_len = 2 * 1024 * 1024 # MB
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diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
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index cfa5c0d..802ffaa 100644
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--- a/tests/qemu-iotests/041.out
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+++ b/tests/qemu-iotests/041.out
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@@ -1,5 +1,5 @@
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-...................................
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+...........................................
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 ----------------------------------------------------------------------
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-Ran 35 tests
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+Ran 43 tests
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 OK
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-- 
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1.7.1
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