NFSv4.1: Allow parallel OPEN/OPEN_DOWNGRADE/CLOSE

Remove the serialisation of OPEN/OPEN_DOWNGRADE and CLOSE calls for the
case of NFSv4.1 and newer.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index a081787..e57290a 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -44,6 +44,7 @@
 #define NFS4_RENEW_TIMEOUT		0x01
 #define NFS4_RENEW_DELEGATION_CB	0x02
 
+struct nfs_seqid_counter;
 struct nfs4_minor_version_ops {
 	u32	minor_version;
 	unsigned init_caps;
@@ -56,6 +57,8 @@
 			struct nfs_fsinfo *);
 	void	(*free_lock_state)(struct nfs_server *,
 			struct nfs4_lock_state *);
+	struct nfs_seqid *
+		(*alloc_seqid)(struct nfs_seqid_counter *, gfp_t);
 	const struct rpc_call_ops *call_sync_ops;
 	const struct nfs4_state_recovery_ops *reboot_recovery_ops;
 	const struct nfs4_state_recovery_ops *nograce_recovery_ops;