linux-kernel - Re: [PATCH 1/2] vfs: dcache: fix deadlock in tree traversal

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Date:	Tue, 18 Sep 2012 11:22:33 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	Al Viro <viro@...iv.linux.org.uk>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, hch@...radead.org,
	Trond.Myklebust@...app.com
Subject: Re: [PATCH 1/2] vfs: dcache: fix deadlock in tree traversal

On Tue, Sep 18, 2012 at 9:27 AM, Miklos Szeredi <miklos@...redi.hu> wrote:
> Linus Torvalds <torvalds@...ux-foundation.org> writes:
>>
>> HOWEVER. Why introduce that new DCACHE_KILLED flag at all? Wouldn't it
>> be much better to just check whether the dentry is hashed instead of
>> introducing a new flag for this case? Couldn't we just check for
>> "d_unhashed()"?
>
> Not good, because an unhashed dentry can stay around and that would mean
> that we'd need to restart the walk until the last ref to the dentry is
> dropped (which can be an arbitrary long time).

Ok, fair enough.

I'll apply your second patch as obviously fixing one issue, and wait
for Al to hopefully come up with something nicer for the first one.

         Linus
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