NFSv4.2: Fix NFS4ERR_STALE error when doing inter server copy

NFS_FS=y as dependency of CONFIG_NFSD_V4_2_INTER_SSC still have
build errors and some configs with NFSD=m to get NFS4ERR_STALE
error when doing inter server copy.

Added ops table in nfs_common for knfsd to access NFS client modules.

Fixes: 3ac3711adb88 ("NFSD: Fix NFS server build errors")
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/fs/nfs_common/nfs_ssc.c b/fs/nfs_common/nfs_ssc.c
new file mode 100644
index 000000000000..f43bbb373913
--- /dev/null
+++ b/fs/nfs_common/nfs_ssc.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * fs/nfs_common/nfs_ssc_comm.c
+ *
+ * Helper for knfsd's SSC to access ops in NFS client modules
+ *
+ * Author: Dai Ngo <dai.ngo@oracle.com>
+ *
+ * Copyright (c) 2020, Oracle and/or its affiliates.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/nfs_ssc.h>
+#include "../nfs/nfs4_fs.h"
+
+MODULE_LICENSE("GPL");
+
+struct nfs_ssc_client_ops_tbl nfs_ssc_client_tbl;
+EXPORT_SYMBOL_GPL(nfs_ssc_client_tbl);
+
+#ifdef CONFIG_NFS_V4_2
+/**
+ * nfs42_ssc_register - install the NFS_V4 client ops in the nfs_ssc_client_tbl
+ * @ops: NFS_V4 ops to be installed
+ *
+ * Return values:
+ *   None
+ */
+void nfs42_ssc_register(const struct nfs4_ssc_client_ops *ops)
+{
+	nfs_ssc_client_tbl.ssc_nfs4_ops = ops;
+}
+EXPORT_SYMBOL_GPL(nfs42_ssc_register);
+
+/**
+ * nfs42_ssc_unregister - uninstall the NFS_V4 client ops from
+ *				the nfs_ssc_client_tbl
+ * @ops: ops to be uninstalled
+ *
+ * Return values:
+ *   None
+ */
+void nfs42_ssc_unregister(const struct nfs4_ssc_client_ops *ops)
+{
+	if (nfs_ssc_client_tbl.ssc_nfs4_ops != ops)
+		return;
+
+	nfs_ssc_client_tbl.ssc_nfs4_ops = NULL;
+}
+EXPORT_SYMBOL_GPL(nfs42_ssc_unregister);
+#endif /* CONFIG_NFS_V4_2 */
+
+#ifdef CONFIG_NFS_V4_2
+/**
+ * nfs_ssc_register - install the NFS_FS client ops in the nfs_ssc_client_tbl
+ * @ops: NFS_FS ops to be installed
+ *
+ * Return values:
+ *   None
+ */
+void nfs_ssc_register(const struct nfs_ssc_client_ops *ops)
+{
+	nfs_ssc_client_tbl.ssc_nfs_ops = ops;
+}
+EXPORT_SYMBOL_GPL(nfs_ssc_register);
+
+/**
+ * nfs_ssc_unregister - uninstall the NFS_FS client ops from
+ *				the nfs_ssc_client_tbl
+ * @ops: ops to be uninstalled
+ *
+ * Return values:
+ *   None
+ */
+void nfs_ssc_unregister(const struct nfs_ssc_client_ops *ops)
+{
+	if (nfs_ssc_client_tbl.ssc_nfs_ops != ops)
+		return;
+	nfs_ssc_client_tbl.ssc_nfs_ops = NULL;
+}
+EXPORT_SYMBOL_GPL(nfs_ssc_unregister);
+
+#else
+void nfs_ssc_register(const struct nfs_ssc_client_ops *ops)
+{
+}
+EXPORT_SYMBOL_GPL(nfs_ssc_register);
+
+void nfs_ssc_unregister(const struct nfs_ssc_client_ops *ops)
+{
+}
+EXPORT_SYMBOL_GPL(nfs_ssc_unregister);
+#endif /* CONFIG_NFS_V4_2 */