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

[Song Liu <song@kernel.org>]

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.

Thanks,
Song