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>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index ecc151697fd4bd81288941848a4b6a76e7563a24..59bb574d7d7c4e976df207fbf4cdb3de4083d007 100644 (file)
--- 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)