Re: [PATCH v4 4/6] block: Support multiple reopening with x-blockdev-reopen

[Vladimir Sementsov-Ogievskiy]

05.05.2021 19:18, Kevin Wolf wrote:
> > And then, bdrv_reopen_multiple() is called with no aio context
> > acquired, and no drained section.. And it shoud be refactored to
> > properly operate with acquiring and realeasing the contexts and
> > drained sections when needed...
> The drained section shouldn't be a problem, we can keep this. In fact,
> we need this, it is a documented requirement of bdrv_reopen_multiple().
> We just need to drop the AioContext lock after drained_begin.
>
> bdrv_reopen_multiple() should really document its requirements regarding
> AioContext locks. It probably doesn't really care, but requires that
> it be called from the main thread.
>
> > (note preexisting problem of reopen, that during reopen the whole tree
> > may be moved to another aio context, but we continue operations with
> > acquired old aio context which is wrong).
> Do we even acquire the old AioContext?

I think, I mean aio_context_acquire(ctx);  in current qmp_x_blockdev_reopen()..

And I remember, that you said about that problem. Still, may be I misunderstood 
(or misremember). Doesn't worth digging, I'd prefer just review v5 with a fresh 
eye when it comes.


--
Best regards,
Vladimir