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RE: [for-4.2 PATCH 3/6] replay: update docs for record/replay with block
From: |
Pavel Dovgalyuk |
Subject: |
RE: [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices |
Date: |
Wed, 25 Sep 2019 12:02:46 +0300 |
> From: Kevin Wolf [mailto:address@hidden]
> Am 20.09.2019 um 09:25 hat Pavel Dovgalyuk geschrieben:
> > > From: Kevin Wolf [mailto:address@hidden]
> > > Am 19.09.2019 um 14:10 hat Pavel Dovgalyuk geschrieben:
> > > > > From: Kevin Wolf [mailto:address@hidden]
> > > > > diff --git a/block/block-backend.c b/block/block-backend.c
> > > > > index 1c605d5444..c57d3d9fdf 100644
> > > > > --- a/block/block-backend.c
> > > > > +++ b/block/block-backend.c
> > > > > @@ -17,6 +17,7 @@
> > > > > #include "block/throttle-groups.h"
> > > > > #include "hw/qdev-core.h"
> > > > > #include "sysemu/blockdev.h"
> > > > > +#include "sysemu/replay.h"
> > > > > #include "sysemu/runstate.h"
> > > > > #include "qapi/error.h"
> > > > > #include "qapi/qapi-events-block.h"
> > > > > @@ -808,6 +809,12 @@ void blk_remove_bs(BlockBackend *blk)
> > > > > int blk_insert_bs(BlockBackend *blk, BlockDriverState *bs, Error
> > > > > **errp)
> > > > > {
> > > > > ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
> > > > > +
> > > > > + if (replay_mode != REPLAY_MODE_NONE && bs->drv !=
> > > > > &bdrv_blkreplay) {
> > > > > + error_setg(errp, "Root node must be blkreplay");
> > > > > + return -ENOTSUP;
> > > > > + }
> > > >
> > > > I guess this is opposite direction - bs->drv is bdrv_file.
> > > > And we should check its parent.
> > >
> > > If bs->drv is bdrv_file, you want this to fail because only
> > > bdrv_blkreplay should be able to be attached to devices.
> >
> > There was a regular rr invocation (as described in docs).
> > And bs->drv always was a pointer to bdrv_file: for original image,
> > and for temporary snapshot.
>
> Hm, what was the actual command line you used? I can see that you have a
> separate -drive for the qcow2 file, so I can see how you get an unused
> BlockBackend for the qcow2 node, but I don't see how it would be a file
> node.
>
> Anyway, this leaves us two options: Either change the recommended
> command line to use -blockdev for the qcow2 file so that no BlockBackend
> is created for it (I think this might be preferable), or restrict the
> error to when the BlockBackend is used.
I started playing with -blockdev: added new blockdev for blkreplay and
constructed the following command line:
-blockdev driver=file,filename=disk.img,node-name=hd0
-blockdev driver=blkreplay,file=hd0,node-name=hd0-rr
-device virtio-blk-device,drive=hd0-rr
However, I get an error: "Could not open 'disk.img': Permission denied"
Everything works when I use this file in '-drive' parameter.
What am I doing wrong?
Pavel Dovgalyuk
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, (continued)
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Kevin Wolf, 2019/09/18
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Pavel Dovgalyuk, 2019/09/18
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Kevin Wolf, 2019/09/19
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Pavel Dovgalyuk, 2019/09/19
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Kevin Wolf, 2019/09/19
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Pavel Dovgalyuk, 2019/09/19
- Re: [Qemu-devel] [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Kevin Wolf, 2019/09/19
- RE: [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Pavel Dovgalyuk, 2019/09/20
- Re: [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Kevin Wolf, 2019/09/20
- RE: [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices, Pavel Dovgalyuk, 2019/09/23
- RE: [for-4.2 PATCH 3/6] replay: update docs for record/replay with block devices,
Pavel Dovgalyuk <=
[Qemu-devel] [for-4.2 PATCH 4/6] replay: don't drain/flush bdrv queue while RR is working, Pavel Dovgalyuk, 2019/09/17
[Qemu-devel] [for-4.2 PATCH 5/6] replay: finish record/replay before closing the disks, Pavel Dovgalyuk, 2019/09/17
[Qemu-devel] [for-4.2 PATCH 6/6] replay: add BH oneshot event for block layer, Pavel Dovgalyuk, 2019/09/17
Re: [Qemu-devel] [for-4.2 PATCH 0/6] Block-related record/replay fixes, no-reply, 2019/09/17
Re: [Qemu-devel] [for-4.2 PATCH 0/6] Block-related record/replay fixes, no-reply, 2019/09/17
Re: [Qemu-devel] [for-4.2 PATCH 0/6] Block-related record/replay fixes, Alex Bennée, 2019/09/17