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Date: Thu, 19 Sep 2013 12:01:47 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: David Howells <dhowells@redhat.com>
Cc: Milosz Tanski <milosz@adfin.com>, Trond.Myklebust@netapp.com,
        jlayton@redhat.com, moseleymark@gmail.com, linux-cachefs@redhat.com,
        linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org
Subject: Re: evict_inode() vs iget5_locked() race [was Re: [Linux-cachefs]
 Blast from the past, CacheFiles: Error: Unexpected object collision]
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On Thu, Sep 19, 2013 at 09:26:49AM +0100, David Howells wrote:

> There's a potential race between evict_inode() and iget5_locked() in which the
> former can be tearing down an inode corresponding to a file whilst the latter
> is trying to set up a new inode corresponding to that same file - but it's
> possible that the cleanups for the former may adversely affect the setups for
> the latter.

evict() calls ->evict_inode() before removing it from hash.  It's called
only with I_FREEING already set.  If find_inode() runs across that
sucker, it will wait for evict() to do
	wake_up_bit(&inode->i_state, __I_NEW);
(after return from ->evict_inode() and after removal from hash chain)
and repeat the search.

Details, please...