[PATCH] place rmap locking in rmap-locking.h

The rmap locking inlines are causing some header file
dependency/ordering problems - move them out of page-flags.h and into
their own header file.

include/linux/page-flags.h

@@ -228,36 +228,6 @@ extern void get_page_state(struct page_state *ret);
 #define ClearPageDirect(page)		clear_bit(PG_direct, &(page)->flags)
 #define TestClearPageDirect(page)	test_and_clear_bit(PG_direct, &(page)->flags)
 
-/*
- * inlines for acquisition and release of PG_chainlock
- */
-static inline void pte_chain_lock(struct page *page)
-{
-	/*
-	 * Assuming the lock is uncontended, this never enters
-	 * the body of the outer loop. If it is contended, then
-	 * within the inner loop a non-atomic test is used to
-	 * busywait with less bus contention for a good time to
-	 * attempt to acquire the lock bit.
-	 */
-	preempt_disable();
-#ifdef CONFIG_SMP
-	while (test_and_set_bit(PG_chainlock, &page->flags)) {
-		while (test_bit(PG_chainlock, &page->flags))
-			cpu_relax();
-	}
-#endif
-}
-
-static inline void pte_chain_unlock(struct page *page)
-{
-#ifdef CONFIG_SMP
-	smp_mb__before_clear_bit();
-	clear_bit(PG_chainlock, &page->flags);
-#endif
-	preempt_enable();
-}
-
 /*
  * The PageSwapCache predicate doesn't use a PG_flag at this time,
  * but it may again do so one day.

include/linux/rmap-locking.h

+/*
+ * include/linux/rmap-locking.h
+ *
+ * Locking primitives for exclusive access to a page's reverse-mapping
+ * pte chain.
+ */
+
+static inline void pte_chain_lock(struct page *page)
+{
+	/*
+	 * Assuming the lock is uncontended, this never enters
+	 * the body of the outer loop. If it is contended, then
+	 * within the inner loop a non-atomic test is used to
+	 * busywait with less bus contention for a good time to
+	 * attempt to acquire the lock bit.
+	 */
+	preempt_disable();
+#ifdef CONFIG_SMP
+	while (test_and_set_bit(PG_chainlock, &page->flags)) {
+		while (test_bit(PG_chainlock, &page->flags))
+			cpu_relax();
+	}
+#endif
+}
+
+static inline void pte_chain_unlock(struct page *page)
+{
+#ifdef CONFIG_SMP
+	smp_mb__before_clear_bit();
+	clear_bit(PG_chainlock, &page->flags);
+#endif
+	preempt_enable();
+}

mm/rmap.c

@@ -25,6 +25,7 @@
 #include <linux/swapops.h>
 #include <linux/slab.h>
 #include <linux/init.h>
+#include <linux/rmap-locking.h>
 
 #include <asm/pgalloc.h>
 #include <asm/rmap.h>

mm/vmscan.c

@@ -25,6 +25,7 @@
 #include <linux/buffer_head.h>		/* for try_to_release_page() */
 #include <linux/mm_inline.h>
 #include <linux/pagevec.h>
+#include <linux/rmap-locking.h>
 
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>