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

From: Zheng Qixing

Date: Mon Jan 05 2026 - 21:45:14 EST

Hi,

在 2025/12/31 19:11, Roman Mamedov 写道:
On Wed, 31 Dec 2025 15:09:47 +0800
Zheng Qixing <zhengqixing@xxxxxxxxxxxxxxx> wrote:

From: Zheng Qixing <zhengqixing@xxxxxxxxxx>

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