linux-kernel - Re: [PATCH 1/6] fs: unify locking semantics for fs freeze / thaw

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Message-ID: <ZIIyOsHlZLHqP0QB@bombadil.infradead.org>
Date:   Thu, 8 Jun 2023 12:55:38 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     djwong@...nel.org, sandeen@...deen.net, song@...nel.org,
        rafael@...nel.org, gregkh@...uxfoundation.org,
        viro@...iv.linux.org.uk, jack@...e.cz, jikos@...nel.org,
        bvanassche@....org, ebiederm@...ssion.com, mchehab@...nel.org,
        keescook@...omium.org, p.raghav@...sung.com, da.gomez@...sung.com,
        linux-fsdevel@...r.kernel.org, kernel@...force.de,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] fs: unify locking semantics for fs freeze / thaw

On Wed, Jun 07, 2023 at 10:01:14PM -0700, Christoph Hellwig wrote:
> On Sun, May 07, 2023 at 06:17:12PM -0700, Luis Chamberlain wrote:
> > Right now freeze_super()  and thaw_super() are called with
> > different locking contexts. To expand on this is messy, so
> > just unify the requirement to require grabbing an active
> > reference and keep the superblock locked.
> > 
> > Suggested-by: Christoph Hellwig <hch@...radead.org>
> > Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> 
> Maybe I'm just getting old, but where did I suggest this?

https://lore.kernel.org/all/20210420120335.GA3604224@infradead.org/

"I don't think we need both variants, just move the locking and s_active
acquisition out of free_super.  Same for the thaw side."

> That being said, holding an active reference over any operation is a
> good thing.  As Jan said it can be done way simpler than this, though.

Great.


  Luis