[pnfs] [PATCH 9/9] pnfs client prevent race in sequence slot

[andros at umich.edu]

From: Andy Adamson <andros at umich.edu>

Move the lock to cover reading the sequence list in rpc_sequence
which allowed multiple rpc's to be in flight with the same slot
sequence id.

Signed-off by: Andy Adamson<andros at umich.edu>
---
 fs/nfs/nfs4state.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 4963454..cbc08af 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -773,15 +773,15 @@ int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task)
 	struct rpc_sequence *sequence = seqid->sequence->sequence;
 	int status = 0;
 
+	spin_lock(&sequence->lock);
 	if (sequence->list.next == &seqid->list)
 		goto out;
-	spin_lock(&sequence->lock);
 	if (sequence->list.next != &seqid->list) {
 		rpc_sleep_on(&sequence->wait, task, NULL, NULL);
 		status = -EAGAIN;
 	}
-	spin_unlock(&sequence->lock);
 out:
+	spin_unlock(&sequence->lock);
 	return status;
 }
 
-- 
1.5.0.2