sunrpc: mark all struct rpc_procinfo instances as const

struct rpc_procinfo contains function pointers, and marking it as
constant avoids it being able to be used as an attach vector for
code injections.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index e9b4c33..c212549 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -270,12 +270,12 @@ static inline bool nfs_match_open_context(const struct nfs_open_context *ctx1,
 }
 
 /* nfs2xdr.c */
-extern struct rpc_procinfo nfs_procedures[];
+extern const struct rpc_procinfo nfs_procedures[];
 extern int nfs2_decode_dirent(struct xdr_stream *,
 				struct nfs_entry *, int);
 
 /* nfs3xdr.c */
-extern struct rpc_procinfo nfs3_procedures[];
+extern const struct rpc_procinfo nfs3_procedures[];
 extern int nfs3_decode_dirent(struct xdr_stream *,
 				struct nfs_entry *, int);
 
@@ -292,7 +292,7 @@ extern const u32 nfs41_maxgetdevinfo_overhead;
 
 /* nfs4proc.c */
 #if IS_ENABLED(CONFIG_NFS_V4)
-extern struct rpc_procinfo nfs4_procedures[];
+extern const struct rpc_procinfo nfs4_procedures[];
 #endif
 
 #ifdef CONFIG_NFS_V4_SECURITY_LABEL