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From 3ab144fe22a867a0ffcce396302b62b0f2ac4c29 Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Fri, 1 Nov 2013 14:23:16 +0100
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Subject: [PATCH 28/81] qcow2: Unset zero_beyond_eof in save_vmstate
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1383315797-30938-3-git-send-email-mreitz@redhat.com>
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Patchwork-id: 55217
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 2/3] qcow2: Unset zero_beyond_eof in save_vmstate
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Bugzilla: 1025740
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Alex Williamson <alex.williamson@redhat.com>
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BZ: 1025740
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Saving the VM state is done using bdrv_pwrite. This function may perform
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a read-modify-write, which in this case results in data being read from
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beyond the end of the virtual disk. Since we are actually trying to
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access an area which is not a part of the virtual disk, zero_beyond_eof
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has to be set to false before performing the partial write, otherwise
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the VM state may become corrupted.
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 6e13610aa454beba52944e8df6d93158d68ab911)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/qcow2.c | 3 +++
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 1 file changed, 3 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow2.c |    3 +++
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 1 files changed, 3 insertions(+), 0 deletions(-)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index f4adf35..c2728c9 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -1718,12 +1718,15 @@ static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
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     BDRVQcowState *s = bs->opaque;
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     int64_t total_sectors = bs->total_sectors;
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     int growable = bs->growable;
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+    bool zero_beyond_eof = bs->zero_beyond_eof;
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     int ret;
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     BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
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     bs->growable = 1;
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+    bs->zero_beyond_eof = false;
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     ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
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     bs->growable = growable;
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+    bs->zero_beyond_eof = zero_beyond_eof;
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     /* bdrv_co_do_writev will have increased the total_sectors value to include
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      * the VM state - the VM state is however not an actual part of the block
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-- 
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1.7.1
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