linux-kernel - Re: dcache: remove trylock loops (was Re: [BUG] lock_parent() breakage when used from shrink_dentry

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Message-ID: <20180313003751.GT30522@ZenIV.linux.org.uk>
Date:   Tue, 13 Mar 2018 00:37:51 +0000
From:   Al Viro <viro@...IV.linux.org.uk>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     John Ogness <john.ogness@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: dcache: remove trylock loops (was Re: [BUG] lock_parent()
 breakage when used from shrink_dentry_list())

On Mon, Mar 12, 2018 at 06:52:31PM -0500, Eric W. Biederman wrote:

> Ah.  I see now there is now the s_roots list that handles
> that bit of strangeness.
> 
> So one path is to simply remove the heuristic from
> path_connected.
> 
> Another path is to have nfsv2 and nfsv3 not set s_root at all.
> Leaving the heuristic working for the rest of the filesystems,
> and generally simplifying the code.
> 
> Something like the diff below I should think.

> +	/* Leave nfsv2 and nfsv3 s_root == NULL */

Now, grep fs/super.c for s_root.  Or try to boot it, for that
matter...