[PATCH] rmap 1 linux/rmap.h

From: Hugh Dickins <hugh@veritas.com>

First of a batch of three rmap patches: this initial batch of three paving
the way for a move to some form of object-based rmap (probably Andrea's, but
drawing from mine too), and making almost no functional change by itself.  A
few days will intervene before the next batch, to give the struct page
changes in the second patch some exposure before proceeding.

rmap 1 create include/linux/rmap.h

Start small: linux/rmap-locking.h has already gathered some declarations
unrelated to locking, and the rest of the rmap declarations were over in
linux/swap.h: gather them all together in linux/rmap.h, and rename the
pte_chain_lock to rmap_lock.

4 files changed, 53 insertions, 40 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index bd6ddb279c55..93f22640b6cb 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -69,7 +69,7 @@
 #define PG_private		12	/* Has something at ->private */
 #define PG_writeback		13	/* Page is under writeback */
 #define PG_nosave		14	/* Used for system suspend/resume */
-#define PG_chainlock		15	/* lock bit for ->pte_chain */
+#define PG_maplock		15	/* Lock bit for rmap to ptes */
 
 #define PG_direct		16	/* ->pte_chain points directly at pte */
 #define PG_mappedtodisk		17	/* Has blocks allocated on-disk */
diff --git a/include/linux/rmap-locking.h b/include/linux/rmap-locking.h
deleted file mode 100644
index cb30ed470cf6..000000000000
--- a/include/linux/rmap-locking.h
+++ /dev/null
@@ -1,23 +0,0 @@
-/*
- * include/linux/rmap-locking.h
- *
- * Locking primitives for exclusive access to a page's reverse-mapping
- * pte chain.
- */
-
-#include <linux/slab.h>
-
-struct pte_chain;
-extern kmem_cache_t *pte_chain_cache;
-
-#define pte_chain_lock(page)	bit_spin_lock(PG_chainlock, (unsigned long *)&page->flags)
-#define pte_chain_unlock(page)	bit_spin_unlock(PG_chainlock, (unsigned long *)&page->flags)
-
-struct pte_chain *pte_chain_alloc(int gfp_flags);
-void __pte_chain_free(struct pte_chain *pte_chain);
-
-static inline void pte_chain_free(struct pte_chain *pte_chain)
-{
-	if (pte_chain)
-		__pte_chain_free(pte_chain);
-}
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
new file mode 100644
index 000000000000..5f9b35f2fa65
--- /dev/null
+++ b/include/linux/rmap.h
@@ -0,0 +1,52 @@
+#ifndef _LINUX_RMAP_H
+#define _LINUX_RMAP_H
+/*
+ * Declarations for Reverse Mapping functions in mm/rmap.c
+ * Its structures are declared within that file.
+ */
+
+#include <linux/config.h>
+#include <linux/linkage.h>
+
+#define rmap_lock(page) \
+	bit_spin_lock(PG_maplock, (unsigned long *)&(page)->flags)
+#define rmap_unlock(page) \
+	bit_spin_unlock(PG_maplock, (unsigned long *)&(page)->flags)
+
+#ifdef CONFIG_MMU
+
+struct pte_chain;
+struct pte_chain *pte_chain_alloc(int gfp_flags);
+void __pte_chain_free(struct pte_chain *pte_chain);
+
+static inline void pte_chain_free(struct pte_chain *pte_chain)
+{
+	if (pte_chain)
+		__pte_chain_free(pte_chain);
+}
+
+struct pte_chain * fastcall
+	page_add_rmap(struct page *, pte_t *, struct pte_chain *);
+void fastcall page_remove_rmap(struct page *, pte_t *);
+
+/*
+ * Called from mm/vmscan.c to handle paging out
+ */
+int fastcall page_referenced(struct page *);
+int fastcall try_to_unmap(struct page *);
+
+#else	/* !CONFIG_MMU */
+
+#define page_referenced(page)	TestClearPageReferenced(page)
+#define try_to_unmap(page)	SWAP_FAIL
+
+#endif	/* CONFIG_MMU */
+
+/*
+ * Return values of try_to_unmap
+ */
+#define SWAP_SUCCESS	0
+#define SWAP_AGAIN	1
+#define SWAP_FAIL	2
+
+#endif	/* _LINUX_RMAP_H */
diff --git a/include/linux/swap.h b/include/linux/swap.h
index d189090cf63a..f911d8afb8a5 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -76,7 +76,6 @@ struct reclaim_state {
 #ifdef __KERNEL__
 
 struct address_space;
-struct pte_chain;
 struct sysinfo;
 struct writeback_control;
 struct zone;
@@ -177,26 +176,11 @@ extern int try_to_free_pages(struct zone **, unsigned int, unsigned int);
 extern int shrink_all_memory(int);
 extern int vm_swappiness;
 
-/* linux/mm/rmap.c */
 #ifdef CONFIG_MMU
-int FASTCALL(page_referenced(struct page *));
-struct pte_chain *FASTCALL(page_add_rmap(struct page *, pte_t *,
-					struct pte_chain *));
-void FASTCALL(page_remove_rmap(struct page *, pte_t *));
-int FASTCALL(try_to_unmap(struct page *));
-
 /* linux/mm/shmem.c */
 extern int shmem_unuse(swp_entry_t entry, struct page *page);
-#else
-#define page_referenced(page)	TestClearPageReferenced(page)
-#define try_to_unmap(page)	SWAP_FAIL
 #endif /* CONFIG_MMU */
 
-/* return values of try_to_unmap */
-#define	SWAP_SUCCESS	0
-#define	SWAP_AGAIN	1
-#define	SWAP_FAIL	2
-
 extern void swap_unplug_io_fn(struct backing_dev_info *);
 
 #ifdef CONFIG_SWAP