Re: [PATCH] md: drop queue limitation for RAID1 and RAID10

[Song Liu <song@kernel.org>]

On Mon, Jan 3, 2022 at 7:33 AM Mariusz Tkaczyk
<mariusz.tkaczyk@linux.intel.com> wrote:
>
> On Sat, 1 Jan 2022 16:30:07 -0800
> Song Liu <song@kernel.org> wrote:
>
> > On Fri, Dec 17, 2021 at 1:30 AM Mariusz Tkaczyk
> > <mariusz.tkaczyk@linux.intel.com> wrote:
> > >
> > > As suggested by Neil Brown[1], this limitation seems to be
> > > deprecated.
> > >
> > > With plugging in use, writes are processed behind the raid thread
> > > and conf->pending_count is not increased. This limitation occurs
> > > only if caller doesn't use plugs.
> > >
> > > It can be avoided and often it is (with plugging). There are no
> > > reports that queue is growing to enormous size so remove queue
> > > limitation for non-plugged IOs too.
> > >
> > > [1]
> > > https://lore.kernel.org/linux-raid/162496301481.7211.18031090130574610495@noble.neil.brown.name
> > >
> > > Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
> >
> > I applied this patch to md-next, cecause it helps simplify Vishal's
> > patches for REQ_NOWAIT. However, I think this change is not complete,
> > as we can now remove pending_count from r1conf and r10conf. Please
> > send patch on top of md-next to clean up pending_count.
> >
> Should I also remove pending_cnt from raid1_plug_cb and raid10_plug_cb?

Yeah, I think we should also remove pending_cnt.

Thanks,
Song