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Date: Fri, 15 Oct 2010 13:52:47 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Nick Piggin <npiggin@kernel.dk>
Cc: Dave Chinner <david@fromorbit.com>, Christoph Hellwig <hch@infradead.org>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 17/18] fs: icache remove inode_lock
Message-ID: <20101015175247.GA6737@infradead.org>
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Thanks for trying to get back to a technical discussion.  Maybe we
can just move the technical comments to direct replies to the patches
and leave this not very helpful subthread behind?

> rcu_read_lock();
> list_for_each_entry(inode, list) {
>     if (inode->blah ...) {
>       spin_lock(&list_lock);
>       if (unlikely(list_empty(&inode->i_list)))
>         continue;
>       do_something(inode);
>    }
> }

But that't not what we do for icache.  For the validity checking during
lookup we check the I_FREEING bit, which is modified under i_lock
and can be read without any locking.  So everything is just fine
when moving on to RCU locking.