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[v7,22/31] NFSv4: Fix a race in nfs_inode_reclaim_delegation()

Message ID 1474565961-21303-23-git-send-email-trond.myklebust@primarydata.com (mailing list archive)
State New, archived
Headers show

Commit Message

Trond Myklebust Sept. 22, 2016, 5:39 p.m. UTC 
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>
---
 fs/nfs/delegation.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)
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Patch

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)