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[50.108.86.94]) by smtp.gmail.com with ESMTPSA id e66sm1194267itd.22.2016.09.22.10.39.56 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 22 Sep 2016 10:39:57 -0700 (PDT) From: Trond Myklebust To: anna.schumaker@netapp.com Cc: linux-nfs@vger.kernel.org, Oleg Drokin Subject: [PATCH v7 22/31] NFSv4: Fix a race in nfs_inode_reclaim_delegation() Date: Thu, 22 Sep 2016 13:39:12 -0400 Message-Id: <1474565961-21303-23-git-send-email-trond.myklebust@primarydata.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1474565961-21303-22-git-send-email-trond.myklebust@primarydata.com> References: <1474565961-21303-1-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-2-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-3-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-4-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-5-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-6-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-7-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-8-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-9-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-10-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-11-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-12-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-13-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-14-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-15-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-16-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-17-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-18-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-19-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-20-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-21-git-send-email-trond.myklebust@primarydata.com> <1474565961-21303-22-git-send-email-trond.myklebust@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If we race with a delegreturn before taking the spin lock, we currently end up dropping the delegation stateid. Signed-off-by: Trond Myklebust --- fs/nfs/delegation.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c index 5de4cfb2ab07..094e0efe6a82 100644 --- a/fs/nfs/delegation.c +++ b/fs/nfs/delegation.c @@ -195,15 +195,13 @@ void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred, rcu_read_unlock(); put_rpccred(oldcred); trace_nfs4_reclaim_delegation(inode, res->delegation_type); - } else { - /* We appear to have raced with a delegation return. */ - spin_unlock(&delegation->lock); - rcu_read_unlock(); - nfs_inode_set_delegation(inode, cred, res); + return; } - } else { - rcu_read_unlock(); + /* We appear to have raced with a delegation return. */ + spin_unlock(&delegation->lock); } + rcu_read_unlock(); + nfs_inode_set_delegation(inode, cred, res); } static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)