linux-kernel - Re: [announce] vfs-scale git tree update

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Message-ID: <AANLkTikYErmu6bNz51iPgjzdOoa8uWNNdn01texihqM6@mail.gmail.com>
Date:	Thu, 13 Jan 2011 12:01:18 +1100
From:	Nick Piggin <npiggin@...il.com>
To:	Ian Kent <raven@...maw.net>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>, aelder@....com,
	Nick Piggin <npiggin@...nel.dk>,
	Al Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [announce] vfs-scale git tree update

On Wed, Jan 12, 2011 at 4:17 PM, Ian Kent <raven@...maw.net> wrote:
> On Wed, 2011-01-12 at 12:41 +0800, Ian Kent wrote:
>> On Tue, 2011-01-11 at 20:06 -0800, Linus Torvalds wrote:
>> > On Tue, Jan 11, 2011 at 7:59 PM, Ian Kent <raven@...maw.net> wrote:

>> > > Yeah, a hangover from changes done over time.
>> > > Not setting the dentry op in ->lookup() should fix this.
>> >
>> > Alex, care to test just removing the d_set_d_op() call from autofs4_lookup()?
>> >
>> > (That code is a bit scary, though - it explicitly makes it a negative
>> > dentry with a d_instantiate(dentry, NULL), and then hides the inode
>> > information away separately. Scary scary)
>>
>> Yeah, but the expire to mount races with autofs are difficult to handle
>> and this approach has worked well under heavy stress testing. It's true
>> that this would almost certainly be bad for a file system that supported
>> a full range of functionality but that's not so for autofs.
>
> I think I have to partly take this back.
> With Nick's recent vfs-scale patches this may not be OK any more since
> the dcache_lock has gone away and, at first glance, it looks like the
> added autofs4_lock spin lock doesn't provide the needed protection.

Hm, what are the concurrencies that you need protection from?
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