linux-kernel - Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

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Message-ID: <13e21e4c9a5841243c8d130cf9324f6cfc4dc2e1.camel@themaw.net>
Date:   Fri, 11 Dec 2020 10:17:47 +0800
From:   Ian Kent <raven@...maw.net>
To:     Fox Chen <foxhlchen@...il.com>
Cc:     akpm@...ux-foundation.org, dhowells@...hat.com,
        gregkh@...uxfoundation.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, miklos@...redi.hu,
        ricklind@...ux.vnet.ibm.com, sfr@...b.auug.org.au, tj@...nel.org,
        viro@...IV.linux.org.uk
Subject: Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency
 improvement

On Fri, 2020-12-11 at 10:01 +0800, Ian Kent wrote:
> 
> > For the patches, there is a mutex_lock in kn->attr_mutex, as Tejun
> > mentioned here 
> > (https://lore.kernel.org/lkml/X8fe0cmu+aq1gi7O@mtj.duckdns.org/),
> > maybe a global 
> > rwsem for kn->iattr will be better??
> 
> I wasn't sure about that, IIRC a spin lock could be used around the
> initial check and checked again at the end which would probably have
> been much faster but much less conservative and a bit more ugly so
> I just went the conservative path since there was so much change
> already.

Sorry, I hadn't looked at Tejun's reply yet and TBH didn't remember
it.

Based on what Tejun said it sounds like that needs work.

Ian