linux-kernel - Re: [PATCH RFC -next 00/26] md/md-bitmap: introduce bitmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZrsJeabpeFdXVfIb@infradead.org>
Date: Tue, 13 Aug 2024 00:21:29 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: song@...nel.org, linux-kernel@...r.kernel.org,
	linux-raid@...r.kernel.org, yukuai3@...wei.com, yi.zhang@...wei.com,
	yangerkun@...wei.com
Subject: Re: [PATCH RFC -next 00/26] md/md-bitmap: introduce bitmap_operations

On Sat, Aug 10, 2024 at 10:08:28AM +0800, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@...wei.com>
> 
> The background is that currently bitmap is using a global spin_lock,
> cauing lock contention and huge IO performance degration for all raid
> levels.
> 
> However, it's impossible to implement a new lock free bitmap with
> current situation that md-bitmap exposes the internal implementation
> with lots of exported apis. Hence bitmap_operations is invented, to
> describe bitmap core implementation, and a new bitmap can be introduced
> with a new bitmap_operations, we only need to switch to the new one
> during initialization.
> 
> And with this we can build bitmap as kernel module, but that's not
> our concern for now.
> 
> Noted I just compile this patchset, not tested yet.

Refactoring the bitmap code to be modular seems like a good idea.

But I'd just turn this into plain function calls and maybe a hidden
data structure if you feel really fancy.  No need to introduce expensive
indirect calls and a separate module.