Date: Thu, 5 Jan 2006 03:00:47 +0200
From: Oleg Drokin <green@linuxhacker.ru>
To: linux-kernel@vger.kernel.org, trond.myklebust@fys.uio.no,
       viro@zeniv.linux.org.uk
Subject: d_instantiate_unique / NFS inode leakage?
Message-ID: <20060105010047.GJ5743@linuxhacker.ru>
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Hello!

   Searching for inode leakage in NFS code (seen in 2.6.14 and 2.6.15 at least,
   have not tried earlier versions), I see suspicious place in
   d_instantiate_unique (the only user happens to be NFS).
   There if we have found aliased dentry that we return, inode reference is
   not dropped and inode is not attached anywhere, so it seems the reference
   to inode is leaked in that case.
   This simple patch below fixes the problem. Unfortunatelly the leakage seems
   to be non-100% in my testing, so I will continue the testing to see
   if I still see inodes to leak or not (no leak seen so far with the patch).

--- fs/dcache.c.orig	2006-01-05 02:28:57.000000000 +0200
+++ fs/dcache.c	2006-01-05 02:32:08.000000000 +0200
@@ -838,6 +838,7 @@ struct dentry *d_instantiate_unique(stru
 		dget_locked(alias);
 		spin_unlock(&dcache_lock);
 		BUG_ON(!d_unhashed(alias));
+		iput(inode);
 		return alias;
 	}
 	list_add(&entry->d_alias, &inode->i_dentry);

Bye,
    Oleg
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