linux-kernel - Re: [PATCH 09/23] md/md-bitmap: add a new method blocks_synced() in bitmap

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Message-ID: <150960a5-376d-61ca-2996-6ce0e553e956@huaweicloud.com>
Date: Tue, 27 May 2025 10:48:25 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Xiao Ni <xni@...hat.com>, Yu Kuai <yukuai1@...weicloud.com>
Cc: hch@....de, colyli@...nel.org, song@...nel.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-raid@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com,
 johnny.chenyi@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH 09/23] md/md-bitmap: add a new method blocks_synced() in
 bitmap_operations

Hi,

在 2025/05/27 10:35, Xiao Ni 写道:
> On Sat, May 24, 2025 at 2:18 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>>
>> From: Yu Kuai <yukuai3@...wei.com>
>>
>> Currently, raid456 must perform a whole array initial recovery to build
>> initail xor data, then IO to the array won't have to read all the blocks
>> in underlying disks.
>>
>> This behavior will affect IO performance a lot, and nowadays there are
>> huge disks and the initial recovery can take a long time. Hence llbitmap
>> will support lazy initial recovery in following patches. This method is
>> used to check if data blocks is synced or not, if not then IO will still
>> have to read all blocks for raid456.
> 
> Hi Kuai
> 
> In function handle_stripe_dirtying, if the io is behind resync, it
> will force rcw. Does this interface have the same function？

This api is not the same, this api is used by lazy initial recovery
for the raid5, means initial recovery is skipped and resync is not
in progress, handle_stripe_dirtying can't handle this case.

Thanks,
Kuai