Re: [Qemu-devel] [PATCH v2 3/9] blockjob: Don't set iostatus of target

[Kevin Wolf]

Am 06.05.2016 um 14:32 hat Max Reitz geschrieben:
> On 06.05.2016 14:01, Max Reitz wrote:
> > On 27.04.2016 15:20, Kevin Wolf wrote:
> >> When block job errors were introduced, we assigned the iostatus of the
> >> target BDS "just in case". The field has never been accessible for the
> >> user because the target isn't listed in query-block.
> >>
> >> Before we can allow the user to have a second BlockBackend on the
> >> target, we need to clean this up. If anything, we would want to set the
> >> iostatus for the internal BB of the job (which we can always do later),
> >> but certainly not for a separate BB which the job doesn't even use.
> >>
> >> As a nice side effect, this gets us rid of another bs->blk use.
> >>
> >> Signed-off-by: Kevin Wolf <address@hidden>
> >> ---
> >>  block/backup.c           | 8 ++++----
> >>  block/mirror.c           | 8 ++++----
> >>  block/stream.c           | 3 +--
> >>  blockjob.c               | 6 +-----
> >>  include/block/blockjob.h | 4 +---
> >>  5 files changed, 11 insertions(+), 18 deletions(-)
> > 
> > Reviewed-by: Max Reitz <address@hidden>
> 
> Maybe I need to take that back. Using e.g. blockdev-backup, you can
> indeed see the target in query-block.
> 
> e.g.:
> 
> (echo "{'execute':'qmp_capabilities'}
>        {'execute':'blockdev-backup',
>         'arguments':{'device':'src','target':'dst',
>         'sync':'full','on-target-error':'enospc'}}";
>  sleep 1;
>  echo "{'execute':'query-block'}") | \
>    x86_64-softmmu/qemu-system-x86_64 \
>        -drive if=none,id=src,file=test.qcow2 \
>        -drive if=none,id=dst,file=mnt/out.qcow2 \
>        -qmp-pretty stdio -nodefaults
> 
> Where mnt is a file system and test.qcow2 is large enough such that an
> ENOSPC will occur.

Hm... Let's pretend we didn't notice. In fact, I don't think this
behaviour is documented and it also doesn't make a lot of sense.

I would be surprised if libvirt made use of it, as there is still the
job iostatus which works in drive-* cases, too.

(Eric?)

> Before this patch, you can see "io-status": "nospace" in query-block for
> dst. After it, it says "io-status": "ok", and after the next it doesn't
> say anything about the status at all anymore.

Simply letting the field disappear sounds like a nice solution.

Kevin

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