NFSD: Split linux/nfs_ssc.h

The nfs_ssc.h header contains both client- and server-side data
structures, which means each of those implementations has to pull in
headers from the other.

Create a linux/nfsd_ssc.h for the server side APIs which no longer
includes uapi/linux/nfs.h either directly or indirectly. Because
nfsd_ssc.h drops the transitive include of the NFS client headers,
fs/nfsd/nfs4proc.c now includes <linux/pagemap.h> directly for
filemap_check_wb_err().

struct nfsd4_ssc_umount_item is private to nfsd. Move it into
fs/nfsd/xdr4.h alongside its only consumers rather than into the
exported nfsd_ssc.h.

As an added clean-up, add missing header guard macros and the
struct file and struct vfsmount forward declarations the server
prototypes need.

Cc: Olga Kornievskaia <okorniev@redhat.com>
Cc: Dai Ngo <dai.ngo@oracle.com>
Link: https://patch.msgid.link/20260721162306.894558-5-cel@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/include/linux/nfsd_ssc.h b/include/linux/nfsd_ssc.h
new file mode 100644
index 000000000000..7001410f01c2
--- /dev/null
+++ b/include/linux/nfsd_ssc.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * include/linux/nfsd_ssc.h
+ *
+ * NFSv4.2 server-to-server copy, NFS server side APIs
+ *
+ * Author: Dai Ngo <dai.ngo@oracle.com>
+ *
+ * Copyright (c) 2020, Oracle and/or its affiliates.
+ */
+
+#ifndef _LINUX_NFSD_SSC_H
+#define _LINUX_NFSD_SSC_H
+
+#include <linux/nfs_fh.h>
+#include <linux/nfs4.h>
+
+struct file;
+struct vfsmount;
+
+#if IS_ENABLED(CONFIG_NFS_V4_2_SSC_HELPER)
+struct file *nfsd42_ssc_open(struct vfsmount *ss_mnt, struct nfs_fh *src_fh,
+			     nfs4_stateid *stateid);
+void nfsd42_ssc_close(struct file *filp);
+#else
+static inline struct file *nfsd42_ssc_open(struct vfsmount *ss_mnt,
+					   struct nfs_fh *src_fh,
+					   nfs4_stateid *stateid)
+{
+	return ERR_PTR(-EIO);
+}
+
+static inline void nfsd42_ssc_close(struct file *filp)
+{
+}
+#endif
+
+#endif /* _LINUX_NFSD_SSC_H */