From f28d7ed454d6abcd776aed1c84013fbf3055651e Mon Sep 17 00:00:00 2001
From: Andreas Dilger <adilger@whamcloud.com>
Date: Fri, 14 Dec 2018 15:43:41 -0700
Subject: [PATCH] LU-8130 libcfs: don't include rhashtable if unavailable

Don't include <linux/rhashtable.h> if it is not available.

Lustre-change: https://review.whamcloud.com/34020
Lustre-commit: 29d627f860bc1963f2103ea441577dbd18d71344

Fixes: ac8d93c9f6f9 ("LU-8130 libcfs: support latest rhashtable API")

Test-Parameters: trivial
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I80b2ee63fb2a438399359f8052a5063429254035
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35565
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---
 libcfs/autoconf/lustre-libcfs.m4         | 12 ++++++++++++
 libcfs/include/libcfs/linux/linux-hash.h |  8 +++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/libcfs/autoconf/lustre-libcfs.m4 b/libcfs/autoconf/lustre-libcfs.m4
index 807e683..06b6502 100644
--- a/libcfs/autoconf/lustre-libcfs.m4
+++ b/libcfs/autoconf/lustre-libcfs.m4
@@ -389,6 +389,16 @@ shrinker_count_objects, [
 ]) # LIBCFS_SHRINKER_COUNT
 
 #
+# Kernel version 3.16 added rhashtable.h in 7e1e77636e36075eb
+#
+AC_DEFUN([LIBCFS_LINUX_RHASHTABLE_H],[
+LB_CHECK_LINUX_HEADER([linux/rhashtable.h], [
+	AC_DEFINE(HAVE_LINUX_RHASHTABLE_H, 1,
+		[linux/rhashtable.h is present])
+])
+]) # LIBCFS_LINUX_RHASHTABLE_H
+
+#
 # Kernel version 3.17 changed hlist_add_after to
 # hlist_add_behind
 #
@@ -1013,6 +1023,8 @@ LIBCFS_KTIME_AFTER
 LIBCFS_KTIME_BEFORE
 LIBCFS_KTIME_COMPARE
 LIBCFS_SHRINKER_COUNT
+# 3.16
+LIBCFS_LINUX_RHASHTABLE_H
 # 3.17
 LIBCFS_HLIST_ADD_AFTER
 LIBCFS_TIMESPEC64
diff --git a/libcfs/include/libcfs/linux/linux-hash.h b/libcfs/include/libcfs/linux/linux-hash.h
index c38d561..ea4ecbe 100644
--- a/libcfs/include/libcfs/linux/linux-hash.h
+++ b/libcfs/include/libcfs/linux/linux-hash.h
@@ -24,7 +24,6 @@
 #define __LIBCFS_LINUX_HASH_H__
 
 #include <linux/dcache.h>
-#include <linux/rhashtable.h>
 
 u64 cfs_hashlen_string(const void *salt, const char *name);
 
@@ -38,6 +37,9 @@ u64 cfs_hashlen_string(const void *salt, const char *name);
 #endif
 #endif /* !HAVE_STRINGHASH */
 
+#ifdef HAVE_LINUX_RHASHTABLE_H
+#include <linux/rhashtable.h>
+
 #ifndef HAVE_RHLTABLE
 struct rhlist_head {
 	struct rhash_head		rhead;
@@ -209,5 +211,9 @@ restart:
 	return NULL;
 }
 #endif /* !HAVE_RHASHTABLE_LOOKUP */
+#else
+#define rhashtable_init(ht, param) 0
+#define rhashtable_destroy(ht) do {} while (0)
+#endif /* HAVE_LINUX_RHASHTABLE_H */
 
 #endif /* __LIBCFS_LINUX_HASH_H__ */
-- 
1.8.3.1