Re: [PATCH v7 md-6.18 11/11] md/md-llbitmap: introduce new lockless bitmap

[Li Nan <linan666@huaweicloud.com>]

在 2025/8/29 16:04, Yu Kuai 写道:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> Redundant data is used to enhance data fault tolerance, and the storage
> method for redundant data vary depending on the RAID levels. And it's
> important to maintain the consistency of redundant data.
> 
> Bitmap is used to record which data blocks have been synchronized and which
> ones need to be resynchronized or recovered. Each bit in the bitmap
> represents a segment of data in the array. When a bit is set, it indicates
> that the multiple redundant copies of that data segment may not be
> consistent. Data synchronization can be performed based on the bitmap after
> power failure or readding a disk. If there is no bitmap, a full disk
> synchronization is required.
> 
> Due to known performance issues with md-bitmap and the unreasonable
> implementations:
> 
>   - self-managed IO submitting like filemap_write_page();
>   - global spin_lock
> 
> I have decided not to continue optimizing based on the current bitmap
> implementation, this new bitmap is invented without locking from IO fast
> path and can be used with fast disks.
> 
> For designs and details, see the comments in drivers/md-llbitmap.c.
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>

LGTM

Reviewed-by: Li Nan <linan122@huawei.com>

-- 
Thanks,
Nan