cryptospore / rpms / qemu-kvm

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From d3ec1ceddceff322c71dae8c6efff7bec166aeb8 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Wed, 8 Jan 2014 19:43:25 +0000
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Subject: [PATCH 01/37] block: fix backing file segfault
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Message-id: <1392117622-28812-2-git-send-email-kwolf@redhat.com>
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Patchwork-id: 57166
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O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 01/37] block: fix backing file segfault
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Bugzilla: 748906
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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From: Peter Feiner <peter@gridcentric.ca>
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When a backing file is opened such that (1) a protocol is directly
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used as the block driver and (2) the block driver has bdrv_file_open,
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bdrv_open_backing_file segfaults. The problem arises because
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bdrv_open_common returns without setting bd->backing_hd->file.
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To effect (1), you seem to have to use the -F flag in qemu-img. There
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are several block drivers that satisfy (2), such as "file" and "nbd".
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Here are some concrete examples:
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    #!/bin/bash
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    echo Test file format
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    ./qemu-img create -f file base.file 1m
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    ./qemu-img create -f qcow2 -F file -o backing_file=base.file\
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        file-overlay.qcow2
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    ./qemu-img convert -O raw file-overlay.qcow2 file-convert.raw
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    echo Test nbd format
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    SOCK=$PWD/nbd.sock
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    ./qemu-img create -f raw base.raw 1m
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    ./qemu-nbd -t -k $SOCK base.raw &
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    trap "kill $!" EXIT
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    while ! test -e $SOCK; do sleep 1; done
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    ./qemu-img create -f qcow2 -F nbd -o backing_file=nbd:unix:$SOCK\
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        nbd-overlay.qcow2
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    ./qemu-img convert -O raw nbd-overlay.qcow2 nbd-convert.raw
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Without this patch, the two qemu-img convert commands segfault.
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This is a regression that was introduced in v1.7 by
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dbecebddfa4932d1c83915bcb9b5ba5984eb91be.
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Signed-off-by: Peter Feiner <peter@gridcentric.ca>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit d80ac658f2caacfb14ea386211c4a9bea0cea280)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block.c | 8 ++++++--
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 1 file changed, 6 insertions(+), 2 deletions(-)
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---
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 block.c |    8 ++++++--
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 1 files changed, 6 insertions(+), 2 deletions(-)
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diff --git a/block.c b/block.c
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index 1433844..df0adf3 100644
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--- a/block.c
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+++ b/block.c
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@@ -978,8 +978,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
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         error_propagate(errp, local_err);
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         return ret;
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     }
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-    pstrcpy(bs->backing_file, sizeof(bs->backing_file),
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-            bs->backing_hd->file->filename);
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+
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+    if (bs->backing_hd->file) {
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+        pstrcpy(bs->backing_file, sizeof(bs->backing_file),
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+                bs->backing_hd->file->filename);
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+    }
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+
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     return 0;
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 }
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-- 
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1.7.1
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