knfsd: nfsv4 delegation recall should take reference on client

It's not enough to take a reference on the delegation object itself; we
need to ensure that the rpc_client won't go away just as we're about to
make an rpc call.
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfs4callback.c

@@ -486,6 +486,7 @@ nfsd4_cb_recall(struct nfs4_delegation *dp)
 	/* Success or failure, now we're either waiting for lease expiration
 	 * or deleg_return. */
 	dprintk("NFSD: nfs4_cb_recall: dp %p dl_flock %p dl_count %d\n",dp, dp->dl_flock, atomic_read(&dp->dl_count));
+	put_nfs4_client(clp);
 	nfs4_put_delegation(dp);
 	return;
 }

fs/nfsd/nfs4state.c

@@ -1345,6 +1345,7 @@ void nfsd_break_deleg_cb(struct file_lock *fl)
 	 * lock) we know the server hasn't removed the lease yet, we know
 	 * it's safe to take a reference: */
 	atomic_inc(&dp->dl_count);
+	atomic_inc(&dp->dl_client->cl_count);
 
 	spin_lock(&recall_lock);
 	list_add_tail(&dp->dl_recall_lru, &del_recall_lru);
@@ -1367,6 +1368,7 @@ void nfsd_break_deleg_cb(struct file_lock *fl)
 		printk(KERN_INFO "NFSD: Callback thread failed for "
 			"for client (clientid %08x/%08x)\n",
 			clp->cl_clientid.cl_boot, clp->cl_clientid.cl_id);
+		put_nfs4_client(dp->dl_client);
 		nfs4_put_delegation(dp);
 	}
 }