NFSv4.1: Fix a deadlock in layoutget

We cannot call nfs4_handle_exception() without first ensuring that the
slot has been freed. If not, we end up deadlocking with the process
waiting for recovery to complete, and recovery waiting for the slot
table to drain.

Fixes: 2e80dbe7ac51 ("NFSv4.1: Close callback races for OPEN, LAYOUTGET...")
Cc: stable@vger.kernel.org # v4.8+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index ecc151697fd4..59bb574d7d7c 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -8490,6 +8490,7 @@ nfs4_layoutget_handle_exception(struct rpc_task *task,
                 goto out;
         }
 
+        nfs4_sequence_free_slot(&lgp->res.seq_res);
         err = nfs4_handle_exception(server, nfs4err, exception);
         if (!status) {
                 if (exception->retry)