drivers: staging: zcache: fix compile error

Fix below compile error:
drivers/built-in.o: In function `zcache_pampd_free':
>> zcache-main.c:(.text+0xb1c8a): undefined reference to `ramster_pampd_free'
>> zcache-main.c:(.text+0xb1cbc): undefined reference to `ramster_count_foreign_pages'
drivers/built-in.o: In function `zcache_pampd_get_data_and_free':
>> zcache-main.c:(.text+0xb1f05): undefined reference to `ramster_count_foreign_pages'
drivers/built-in.o: In function `zcache_cpu_notifier':
>> zcache-main.c:(.text+0xb228d): undefined reference to `ramster_cpu_up'
>> zcache-main.c:(.text+0xb2339): undefined reference to `ramster_cpu_down'
drivers/built-in.o: In function `zcache_pampd_create':
>> (.text+0xb26ce): undefined reference to `ramster_count_foreign_pages'
drivers/built-in.o: In function `zcache_pampd_create':
>> (.text+0xb27ef): undefined reference to `ramster_count_foreign_pages'
drivers/built-in.o: In function `zcache_put_page':
>> (.text+0xb299f): undefined reference to `ramster_do_preload_flnode'
drivers/built-in.o: In function `zcache_flush_page':
>> (.text+0xb2ea3): undefined reference to `ramster_do_preload_flnode'
drivers/built-in.o: In function `zcache_flush_object':
>> (.text+0xb307c): undefined reference to `ramster_do_preload_flnode'
drivers/built-in.o: In function `zcache_init':
>> zcache-main.c:(.text+0xb3629): undefined reference to `ramster_register_pamops'
>> zcache-main.c:(.text+0xb3868): undefined reference to `ramster_init'
>> drivers/built-in.o:(.rodata+0x15058): undefined reference to `ramster_foreign_eph_pages'
>> drivers/built-in.o:(.rodata+0x15078): undefined reference to `ramster_foreign_pers_pages'
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/zcache/ramster.h

@@ -11,10 +11,6 @@
 #ifndef _ZCACHE_RAMSTER_H_
 #define _ZCACHE_RAMSTER_H_
 
-#ifdef CONFIG_RAMSTER_MODULE
-#define CONFIG_RAMSTER
-#endif
-
 #ifdef CONFIG_RAMSTER
 #include "ramster/ramster.h"
 #else

drivers/staging/zcache/ramster/debug.c

 #include <linux/atomic.h>
 #include "debug.h"
 
+ssize_t ramster_foreign_eph_pages;
+ssize_t ramster_foreign_pers_pages;
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 

drivers/staging/zcache/ramster/ramster.c

@@ -66,8 +66,6 @@ static int ramster_remote_target_nodenum __read_mostly = -1;
 
 /* Used by this code. */
 long ramster_flnodes;
-ssize_t ramster_foreign_eph_pages;
-ssize_t ramster_foreign_pers_pages;
 /* FIXME frontswap selfshrinking knobs in debugfs? */
 
 static LIST_HEAD(ramster_rem_op_list);
@@ -399,14 +397,18 @@ void ramster_count_foreign_pages(bool eph, int count)
 			inc_ramster_foreign_eph_pages();
 		} else {
 			dec_ramster_foreign_eph_pages();
+#ifdef CONFIG_RAMSTER_DEBUG
 			WARN_ON_ONCE(ramster_foreign_eph_pages < 0);
+#endif
 		}
 	} else {
 		if (count > 0) {
 			inc_ramster_foreign_pers_pages();
 		} else {
 			dec_ramster_foreign_pers_pages();
+#ifdef CONFIG_RAMSTER_DEBUG
 			WARN_ON_ONCE(ramster_foreign_pers_pages < 0);
+#endif
 		}
 	}
 }