Re: [RFC PATCH 0/5] md/raid1: introduce a new sync action to repair badblocks

Hi,

在 2025/12/31 19:11, Roman Mamedov 写道:
> On Wed, 31 Dec 2025 15:09:47 +0800
> Zheng Qixing <[email protected]> wrote:
>
>> From: Zheng Qixing <[email protected]>
>>
>> In RAID1, some sectors may be marked as bad blocks due to I/O errors.
>> In certain scenarios, these bad blocks might not be permanent, and
>> issuing I/Os again could succeed.
>>
>> To address this situation, a new sync action ('rectify') introduced
>> into RAID1 , allowing users to actively trigger the repair of existing
>> bad blocks and clear it in sys bad_blocks.
>>
>> When echo rectify into /sys/block/md*/md/sync_action, a healthy disk is
>> selected from the array to read data and then writes it to the disk where
>> the bad block is located. If the write request succeeds, the bad block
>> record can be cleared.
> Could you also check here that it reads back successfully, and only then clear?
>
> Otherwise there are cases when the block won't read even after rewriting it.

Thanks for your suggestions.

I'm a bit worried that reading the data again before clearing the bad 
blocks might

affect the performance of the bad block repair process.


> Side note, on some hardware it might be necessary to rewrite a larger area
> around the problematic block, to finally trigger a remap. Not 512B, but at
> least the native sector size, which is often 4K.


Are you referring to the case where we have logical 512B sectors but 
physical 4K sectors?

I'm not entirely clear on one aspect:

Can a physical 4K block have partial recovery (e.g., one 512B sector 
succeeds while the other 7 fail)?


Thanks,

Qixing