Kevin, can you give any hint on using blockdev through the command line? Pavel Dovgalyuk
> -----Original Message----- > From: Pavel Dovgalyuk [mailto:dovga...@ispras.ru] > Sent: Wednesday, September 25, 2019 12:03 PM > To: 'Kevin Wolf' > Cc: qemu-devel@nongnu.org; peter.mayd...@linaro.org; > crosthwaite.pe...@gmail.com; > boost.li...@gmail.com; artem.k.pisare...@gmail.com; quint...@redhat.com; > ciro.santi...@gmail.com; jasow...@redhat.com; m...@redhat.com; > arm...@redhat.com; > mre...@redhat.com; maria.klimushenk...@ispras.ru; kra...@redhat.com; > pavel.dovga...@ispras.ru; > thomas.dull...@googlemail.com; pbonz...@redhat.com; alex.ben...@linaro.org; > dgilb...@redhat.com; r...@twiddle.net > Subject: RE: [for-4.2 PATCH 3/6] replay: update docs for record/replay with > block devices > > > From: Kevin Wolf [mailto:kw...@redhat.com] > > Am 20.09.2019 um 09:25 hat Pavel Dovgalyuk geschrieben: > > > > From: Kevin Wolf [mailto:kw...@redhat.com] > > > > Am 19.09.2019 um 14:10 hat Pavel Dovgalyuk geschrieben: > > > > > > From: Kevin Wolf [mailto:kw...@redhat.com] > > > > > > 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 >
