Re: [PATCH 2/2] nbd/server: Use drained block ops to quiesce the server

[Sergio Lopez]

On Tue, Jun 01, 2021 at 04:29:07PM -0500, Eric Blake wrote:
> On Tue, Jun 01, 2021 at 07:57:28AM +0200, Sergio Lopez wrote:
> > Before switching between AioContexts we need to make sure that we're
> > fully quiesced ("nb_requests == 0" for every client) when entering the
> > drained section.
> > 
> > To do this, we set "quiescing = true" for every client on
> > ".drained_begin" to prevent new coroutines to be created, and check if
> 
> s/to be created/from being created/
> 
> > "nb_requests == 0" on ".drained_poll". Finally, once we're exiting the
> > drained section, on ".drained_end" we set "quiescing = false" and
> > call "nbd_client_receive_next_request()" to resume the processing of
> > new requests.
> > 
> > With these changes, "blk_aio_attach()" and "blk_aio_detach()" can be
> > reverted to be as simple as they were before f148ae7d36.
> 
> Is that reversion planned to be patch 3 of your series in v2?

Actually, we need part of the changes introduced in f148ae7d36, so
it's probably simpler to manually revert "blk_aio_attach()" and
"blk_aio_detach()" here than doing an actual reversion and then
reintroducing the changes.

Thanks,
Sergio.

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