Date: Sun, 13 Jul 2014 04:00:47 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Jeff Layton <jlayton@primarydata.com>
Cc: linux-nfs@vger.kernel.org
Subject: nfsd4_locku / nfs4_free_lock_stateid question
Message-ID: <20140713110047.GA28727@infradead.org>
MIME-Version: 1.0
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Sender: linux-nfs-owner@vger.kernel.org

Hi Jeff,

while reviewing some of your patches I've started wondering about
some v4 locking code.

In nfsd4_locku we're doing a call to find_any_file to grab a file
structure for the lock stateid, which nfs4_free_lock_stateid tries to
close. But what guarantees that we're actually getting the same file
descriptor back?

The nfs4_file is shared by and stateid that access a given inode,
so the first call to find_any_file might return the read/only file
structure because that's the only one available so far, while
by the time we unlock we might have a read/write and/or write-only file
available as well, which find_any_file will return.

It seems like the lock stateid needs a pointer to the actual file
locked, and keep a reference to it independent of the nfs4_file, or am I
missing something?