NFSD: Remove '#include "xdr.h"' from fs/nfsd/xdr3.h

Separate the dependencies between fs/nfsd/xdr3.h and fs/nfsd/xdr.h
so that NFSD's NFSv2 and NFSv3 implementations can be converted
independently to use xdrgen.

The only reason xdr3.h includes xdr.h is to pick up the definition
of struct nfsd_fhandle. xdr3.h does not name the structure itself;
its consumers nfs3proc.c and nfs3xdr.c do, reaching the definition
through xdr3.h. That structure wraps a single struct svc_fh, which
is defined in nfsfh.h, a header both xdr.h and xdr3.h already include
via vfs.h. Move struct nfsd_fhandle next to svc_fh in nfsfh.h so the
two XDR headers share one definition and xdr3.h no longer depends on
xdr.h. nfs2acl.c, which includes both headers, then sees that single
definition instead of a clashing pair.

Stripping xdr.h to its own dependencies also removes the
transitive route by which nfsxdr.c and nfs3xdr.c reached nfsd.h.
Both expand the nfserr_* and nfs_ok status-code macros that
nfsd.h defines, so each gains a direct #include of nfsd.h in
place of the one xdr.h used to supply.

As a clean-up, the #includes at the top of both header files are
made the same.

Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260916162859.2051-7-cel@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>

fs/nfsd/nfs2acl.c

@@ -10,8 +10,8 @@
 /* FIXME: nfsacl.h is a broken header */
 #include <linux/nfsacl.h>
 #include <linux/gfp.h>
-#include <linux/nfs3.h>
 #include "cache.h"
+#include "xdr.h"
 #include "xdr3.h"
 #include "vfs.h"
 

fs/nfsd/nfs3xdr.c

@@ -10,6 +10,8 @@
 #include <linux/namei.h>
 #include <linux/nfs3.h>
 #include <linux/sunrpc/svc_xprt.h>
+
+#include "nfsd.h"
 #include "xdr3.h"
 #include "auth.h"
 #include "netns.h"

fs/nfsd/nfsfh.h

@@ -111,6 +111,11 @@ typedef struct svc_fh {
 	struct kstat		fh_post_attr;	/* full attrs after operation */
 	u64			fh_post_change; /* nfsv4 change; see above */
 } svc_fh;
+
+struct nfsd_fhandle {
+	struct svc_fh		fh;
+};
+
 #define NFSD4_FH_FOREIGN (1<<0)
 #define SET_FH_FLAG(c, f) ((c)->fh_flags |= (f))
 #define HAS_FH_FLAG(c, f) ((c)->fh_flags & (f))

fs/nfsd/xdr.h

@@ -5,13 +5,8 @@
 #define _LINUX_NFSD_XDR_H
 
 #include <linux/vfs.h>
-#include "nfsd.h"
-#include "nfsfh.h"
-#include "vfs.h"
 
-struct nfsd_fhandle {
-	struct svc_fh		fh;
-};
+#include "vfs.h"
 
 struct nfsd_sattrargs {
 	struct svc_fh		fh;

fs/nfsd/xdr3.h

@@ -8,7 +8,8 @@
 #ifndef _LINUX_NFSD_XDR3_H
 #define _LINUX_NFSD_XDR3_H
 
-#include "xdr.h"
+#include <linux/vfs.h>
+
 #include "vfs.h"
 
 struct nfsd3_sattrargs {