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From f50d8d218780ea455bb7dc6d7ccdd0c5b931f4a8 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Tue, 5 Nov 2013 14:09:17 +0100
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Subject: [PATCH 64/87] block: fix backing file overriding
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1383660558-32096-24-git-send-email-kwolf@redhat.com>
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Patchwork-id: 55402
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 23/24] block: fix backing file overriding
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Bugzilla: 978402
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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From: Fam Zheng <famz@redhat.com>
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Providing backing.file.filename doesn't override backing file as expected:
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    $ x86_64-softmmu/qemu-system-x86_64 -drive \
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        file=/tmp/child.qcow2,backing.file.filename=/tmp/fake.qcow2
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    qemu-system-x86_64: -drive \
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        file=/tmp/child.qcow2,backing.file.filename=/tmp/fake.qcow2: could not
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        open disk image /tmp/child.qcow2: Can't specify 'file' and 'filename'
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        options at the same time
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With
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    $ qemu-img info /tmp/child.qcow2
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    image: /tmp/child.qcow2
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    file format: qcow2
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    virtual size: 1.0G (1073741824 bytes)
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    disk size: 196K
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    cluster_size: 65536
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    backing file: /tmp/fake.qcow2
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This fixes it by calling bdrv_get_full_backing_filename only if
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backing.file.filename is not provided. Also save the backing file name
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to bs->backing_file so the information is correct with HMP "info block".
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit dbecebddfa4932d1c83915bcb9b5ba5984eb91be)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block.c | 7 +++++--
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 1 file changed, 5 insertions(+), 2 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block.c |    7 +++++--
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 1 files changed, 5 insertions(+), 2 deletions(-)
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diff --git a/block.c b/block.c
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index d11661a..01c11ee 100644
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--- a/block.c
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+++ b/block.c
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@@ -956,11 +956,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
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     } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
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         QDECREF(options);
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         return 0;
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+    } else {
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+        bdrv_get_full_backing_filename(bs, backing_filename,
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+                                       sizeof(backing_filename));
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     }
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     bs->backing_hd = bdrv_new("");
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-    bdrv_get_full_backing_filename(bs, backing_filename,
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-                                   sizeof(backing_filename));
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     if (bs->backing_format[0] != '\0') {
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         back_drv = bdrv_find_format(bs->backing_format);
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@@ -972,6 +973,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
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     ret = bdrv_open(bs->backing_hd,
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                     *backing_filename ? backing_filename : NULL, options,
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                     back_flags, back_drv, &local_err);
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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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     if (ret < 0) {
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         bdrv_delete(bs->backing_hd);
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         bs->backing_hd = NULL;
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-- 
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1.7.1
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