Re: [PATCH 01/11] block: add new BlockDriver handler: bdrv_cancel_in_flight

[Vladimir Sementsov-Ogievskiy]

21.01.2021 01:27, Eric Blake wrote:
> On 11/18/20 12:04 PM, Vladimir Sementsov-Ogievskiy wrote:
> > It will be used to stop retrying NBD requests on mirror cancel.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> > ---
> >   include/block/block.h     |  3 +++
> >   include/block/block_int.h |  9 +++++++++
> >   block/io.c                | 11 +++++++++++
> >   3 files changed, 23 insertions(+)
>
> How does this relate to the recent addition of the QMP yank command?

Hmm. Don't know.. Looking in spec:

# Currently implemented yank instances:
#  - nbd block device:
#    Yanking it will shut down the connection to the nbd server without
#    attempting to reconnect.

Looks like a close thing. But actually, I don't want to stop reconnecting 
process, but only cancel some requests which we don't want to wait for. After 
that, the nbd node may successfully reconnect and continue to work.

> > +++ b/include/block/block_int.h
> > @@ -344,6 +344,15 @@ struct BlockDriver {
> >           bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum,
> >           int64_t *map, BlockDriverState **file);
> >   
> > +    /*
> > +     * This informs the driver that we are not more interested in in-flight
>
> that we are no longer interested in the result of in-flight requests, so
>
> > +     * requests results, so don't waste the time if possible.
> > +     *
> > +     * The example usage is to not wait for nbd target nodedreconnect timeout 
> > on
> > +     * job-cancel.
>
> One example usage is to avoid waiting for an nbd target node reconnect
> timeout during job-cancel.
>
> Reviewed-by: Eric Blake <eblake@redhat.com>


--
Best regards,
Vladimir