From b1a318de9bc4946ad4a20481ab3ce28c2e8cd72c Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Thu, 22 Sep 2016 13:39:12 -0400
Subject: [PATCH] NFSv4: Fix a race in nfs_inode_reclaim_delegation()
If we race with a delegreturn before taking the spin lock, we
currently end up dropping the delegation stateid.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
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 5de4cfb2ab07b0..094e0efe6a82da 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)
--
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