linux-kernel - Re: [PATCH 3/3] fs: rcu protect inode hash lookups

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Message-ID: <1288625362.2660.108.camel@edumazet-laptop>
Date:	Mon, 01 Nov 2010 16:29:22 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Dave Chinner <david@...morbit.com>
Cc:	viro@...IV.linux.org.uk, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH 3/3] fs: rcu protect inode hash lookups

Le mardi 02 novembre 2010 à 00:44 +1100, Dave Chinner a écrit :

> Perhaps you should rename that file "slab_destroy_by_rcu-tips.txt",
> because the current name seems unrelated to the contents. :/
> 

Hmm, I dont know, this doc really is about the nulls thing.

This stuff also addressed one problem I forgot to tell you about: During
a lookup, you might find an item that is moved to another chain by
another cpu, so your lookup is redirected to another chain. You can miss
your target.

You must find a way to detect such thing to restart the lookup at the
beginning (of the right chain).

Either you stick the chain number in a new inode field (that costs extra
memory), or you use the 'nulls' value that can let you know if you ended
your lookup in the right chain.

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