[PATCH] fix percpu_counter_mod linkage problem

If both ext2 and ext3 are built as modules there is nothing to pull
percpu_counter_mod() into the kernel build and the ext2 and ext3 modules do
not load.

So move percpu_counter_mod() out of lib.a.

lib/Makefile

@@ -9,7 +9,6 @@ lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
 
 lib-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
-lib-$(CONFIG_SMP) += percpu_counter.o
 
 ifneq ($(CONFIG_HAVE_DEC_LOCK),y) 
   lib-y += dec_and_lock.o

lib/percpu_counter.c

-#include <linux/module.h>
-#include <linux/percpu_counter.h>
-#include <linux/sched.h>
-
-void percpu_counter_mod(struct percpu_counter *fbc, long amount)
-{
-	int cpu = get_cpu();
-	long count = fbc->counters[cpu].count;
-
-	count += amount;
-	if (count >= FBC_BATCH || count <= -FBC_BATCH) {
-		spin_lock(&fbc->lock);
-		fbc->count += count;
-		spin_unlock(&fbc->lock);
-		count = 0;
-	}
-	fbc->counters[cpu].count = count;
-	put_cpu();
-}
-
-EXPORT_SYMBOL(percpu_counter_mod);

mm/swap.c

@@ -14,6 +14,7 @@
  */
 
 #include <linux/mm.h>
+#include <linux/sched.h>
 #include <linux/kernel_stat.h>
 #include <linux/swap.h>
 #include <linux/mman.h>
@@ -23,6 +24,8 @@
 #include <linux/module.h>
 #include <linux/mm_inline.h>
 #include <linux/buffer_head.h>	/* for try_to_release_page() */
+#include <linux/module.h>
+#include <linux/percpu_counter.h>
 #include <linux/percpu.h>
 
 /* How many pages do we try to swap or page in/out together? */
@@ -380,6 +383,24 @@ void vm_acct_memory(long pages)
 EXPORT_SYMBOL(vm_acct_memory);
 #endif
 
+#ifdef CONFIG_SMP
+void percpu_counter_mod(struct percpu_counter *fbc, long amount)
+{
+	int cpu = get_cpu();
+	long count = fbc->counters[cpu].count;
+
+	count += amount;
+	if (count >= FBC_BATCH || count <= -FBC_BATCH) {
+		spin_lock(&fbc->lock);
+		fbc->count += count;
+		spin_unlock(&fbc->lock);
+		count = 0;
+	}
+	fbc->counters[cpu].count = count;
+	put_cpu();
+}
+EXPORT_SYMBOL(percpu_counter_mod);
+#endif
 
 /*
  * Perform any setup for the swap system