Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <da8aacb2-ec52-ed7a-8857-1cf89e7de751@molgen.mpg.de>
Date:   Wed, 31 May 2023 09:57:54 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.11.0
Subject: Re: [PATCH -next v3 6/7] md/raid1-10: don't handle pluged bio by
 daemon thread
Content-Language: en-US
To:     Yu Kuai <yukuai1@huaweicloud.com>
Cc:     song@kernel.org, neilb@suse.de, akpm@osdl.org, xni@redhat.com,
        linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
        yukuai3@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com
References: <20230529131106.2123367-1-yukuai1@huaweicloud.com>
 <20230529131106.2123367-7-yukuai1@huaweicloud.com>
From:   Paul Menzel <pmenzel@molgen.mpg.de>
In-Reply-To: <20230529131106.2123367-7-yukuai1@huaweicloud.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

Dear Yu,


Thank you for your patch. Some minor nits in case you should resend this.

In the summary/title it should be plug*g*ed.

Am 29.05.23 um 15:11 schrieb Yu Kuai:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> current->bio_list will be set under submit_bio() context, in this case
> bitmap io will be added to the list and wait for current io submission to

1.  I’d use present tense: s/will be set/is set/; s/will be added/is added/
2.  wait*s*

> finish, while current io submission must wait for bitmap io to be done.
> commit 874807a83139 ("md/raid1{,0}: fix deadlock in bitmap_unplug.") fix
> the deadlock by handling plugged bio by daemon thread.
> 
> On the one hand, the deadlock won't exist after commit a214b949d8e3
> ("blk-mq: only flush requests from the plug in blk_mq_submit_bio"). On
> the other hand, current solution makes it impossible to flush plugged bio
> in raid1/10_make_request(), because this will cause that all the writes
> will goto daemon thread.

s/goto/go to/


Kind regards,

Paul


> In order to limit the number of plugged bio, commit 874807a83139
> ("md/raid1{,0}: fix deadlock in bitmap_unplug.") is reverted, and the
> deadlock is fixed by handling bitmap io asynchronously.
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
>   drivers/md/raid1-10.c | 14 ++++++++++++++
>   drivers/md/raid1.c    |  4 ++--
>   drivers/md/raid10.c   |  8 +++-----
>   3 files changed, 19 insertions(+), 7 deletions(-)

[…]