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, 67 insertions, 0 deletions

diff --git a/include/linux/nfs_ssc.h b/include/linux/nfs_ssc.h
new file mode 100644
index 000000000000..f5ba0fbff72f
--- /dev/null
+++ b/include/linux/nfs_ssc.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * include/linux/nfs_ssc.h
+ *
+ * Author: Dai Ngo <dai.ngo@oracle.com>
+ *
+ * Copyright (c) 2020, Oracle and/or its affiliates.
+ */
+
+#include <linux/nfs_fs.h>
+
+extern struct nfs_ssc_client_ops_tbl nfs_ssc_client_tbl;
+
+/*
+ * NFS_V4
+ */
+struct nfs4_ssc_client_ops {
+	struct file *(*sco_open)(struct vfsmount *ss_mnt,
+		struct nfs_fh *src_fh, nfs4_stateid *stateid);
+	void (*sco_close)(struct file *filep);
+};
+
+/*
+ * NFS_FS
+ */
+struct nfs_ssc_client_ops {
+	void (*sco_sb_deactive)(struct super_block *sb);
+};
+
+struct nfs_ssc_client_ops_tbl {
+	const struct nfs4_ssc_client_ops *ssc_nfs4_ops;
+	const struct nfs_ssc_client_ops *ssc_nfs_ops;
+};
+
+extern void nfs42_ssc_register_ops(void);
+extern void nfs42_ssc_unregister_ops(void);
+
+extern void nfs42_ssc_register(const struct nfs4_ssc_client_ops *ops);
+extern void nfs42_ssc_unregister(const struct nfs4_ssc_client_ops *ops);
+
+#ifdef CONFIG_NFSD_V4_2_INTER_SSC
+static inline struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
+		struct nfs_fh *src_fh, nfs4_stateid *stateid)
+{
+	if (nfs_ssc_client_tbl.ssc_nfs4_ops)
+		return (*nfs_ssc_client_tbl.ssc_nfs4_ops->sco_open)(ss_mnt, src_fh, stateid);
+	return ERR_PTR(-EIO);
+}
+
+static inline void nfs42_ssc_close(struct file *filep)
+{
+	if (nfs_ssc_client_tbl.ssc_nfs4_ops)
+		(*nfs_ssc_client_tbl.ssc_nfs4_ops->sco_close)(filep);
+}
+#endif
+
+/*
+ * NFS_FS
+ */
+extern void nfs_ssc_register(const struct nfs_ssc_client_ops *ops);
+extern void nfs_ssc_unregister(const struct nfs_ssc_client_ops *ops);
+
+static inline void nfs_do_sb_deactive(struct super_block *sb)
+{
+	if (nfs_ssc_client_tbl.ssc_nfs_ops)
+		(*nfs_ssc_client_tbl.ssc_nfs_ops->sco_sb_deactive)(sb);
+}