Commit b2e18538 authored by Rik van Riel's avatar Rik van Riel Committed by Linus Torvalds
Browse files

define page_file_cache() function 



Define page_file_cache() function to answer the question:
	is page backed by a file?

Originally part of Rik van Riel's split-lru patch.  Extracted to make
available for other, independent reclaim patches.

Moved inline function to linux/mm_inline.h where it will be needed by
subsequent "split LRU" and "noreclaim" patches.

Unfortunately this needs to use a page flag, since the PG_swapbacked state
needs to be preserved all the way to the point where the page is last
removed from the LRU.  Trying to derive the status from other info in the
page resulted in wrong VM statistics in earlier split VM patchsets.

The total number of page flags in use on a 32 bit machine after this patch
is 19.

[akpm@linux-foundation.org: fix up out-of-order merge fallout]
[hugh@veritas.com: splitlru: shmem_getpage SetPageSwapBacked sooner[
Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: default avatarMinChan Kim <minchan.kim@gmail.com>
Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 68a22394

include/linux/mm_inline.h

+27 −0
Original line number Diff line number Diff line 
#ifndef LINUX_MM_INLINE_H

#define LINUX_MM_INLINE_H



/**

 * page_is_file_cache - should the page be on a file LRU or anon LRU?

 * @page: the page to test

 *

 * Returns !0 if @page is page cache page backed by a regular filesystem,

 * or 0 if @page is anonymous, tmpfs or otherwise ram or swap backed.

 * Used by functions that manipulate the LRU lists, to sort a page

 * onto the right LRU list.

 *

 * We would like to get this info without a page flag, but the state

 * needs to survive until the page is last deleted from the LRU, which

 * could be as far down as __page_cache_release.

 */

static inline int page_is_file_cache(struct page *page)

{

	if (PageSwapBacked(page))

		return 0;



	/* The page is page cache backed by a normal filesystem. */

	return 1;

}



static inline void

add_page_to_lru_list(struct zone *zone, struct page *page, enum lru_list l)

{
@@ -65,3 +90,5 @@ static inline enum lru_list page_lru(struct page *page) 


	return lru;

}



#endif

include/linux/page-flags.h

+6 −2
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ enum pageflags { 
	PG_mappedtodisk,	/* Has blocks allocated on-disk */

	PG_reclaim,		/* To be reclaimed asap */

	PG_buddy,		/* Page is free, on buddy lists */

	PG_swapbacked,		/* Page is backed by RAM/swap */

#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR

	PG_uncached,		/* Page has been mapped as uncached */

#endif
@@ -176,6 +177,7 @@ PAGEFLAG(SavePinned, savepinned); /* Xen */ 
PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)

PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)

	__SETPAGEFLAG(Private, private)

PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)



__PAGEFLAG(SlobPage, slob_page)

__PAGEFLAG(SlobFree, slob_free)
@@ -334,7 +336,8 @@ static inline void __ClearPageTail(struct page *page) 
 * Flags checked in bad_page().  Pages on the free list should not have

 * these flags set.  It they are, there is a problem.

 */

#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | 1 << PG_reclaim | 1 << PG_dirty)

#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | \

		1 << PG_reclaim | 1 << PG_dirty | 1 << PG_swapbacked)



/*

 * Flags checked when a page is freed.  Pages being freed should not have
@@ -347,7 +350,8 @@ static inline void __ClearPageTail(struct page *page) 
 * Pages being prepped should not have these flags set.  It they are, there

 * is a problem.

 */

#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | 1 << PG_reserved | 1 << PG_dirty)

#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | \

		1 << PG_reserved | 1 << PG_dirty | 1 << PG_swapbacked)



#endif /* !__GENERATING_BOUNDS_H */

#endif	/* PAGE_FLAGS_H */

mm/memory.c

+3 −0
Original line number Diff line number Diff line
@@ -1888,6 +1888,7 @@ gotten: 
		ptep_clear_flush_notify(vma, address, page_table);

		set_pte_at(mm, address, page_table, entry);

		update_mmu_cache(vma, address, entry);

		SetPageSwapBacked(new_page);

		lru_cache_add_active(new_page);

		page_add_new_anon_rmap(new_page, vma, address);
@@ -2382,6 +2383,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 
	if (!pte_none(*page_table))

		goto release;

	inc_mm_counter(mm, anon_rss);

	SetPageSwapBacked(page);

	lru_cache_add_active(page);

	page_add_new_anon_rmap(page, vma, address);

	set_pte_at(mm, address, page_table, entry);
@@ -2523,6 +2525,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
		set_pte_at(mm, address, page_table, entry);

		if (anon) {

                        inc_mm_counter(mm, anon_rss);

			SetPageSwapBacked(page);

                        lru_cache_add_active(page);

                        page_add_new_anon_rmap(page, vma, address);

		} else {

mm/migrate.c

+2 −0
Original line number Diff line number Diff line
@@ -572,6 +572,8 @@ static int move_to_new_page(struct page *newpage, struct page *page) 
	/* Prepare mapping for the new page.*/

	newpage->index = page->index;

	newpage->mapping = page->mapping;

	if (PageSwapBacked(page))

		SetPageSwapBacked(newpage);



	mapping = page_mapping(page);

	if (!mapping)

mm/page_alloc.c

+2 −0
Original line number Diff line number Diff line
@@ -462,6 +462,8 @@ static inline int free_pages_check(struct page *page) 
		bad_page(page);

	if (PageDirty(page))

		__ClearPageDirty(page);

	if (PageSwapBacked(page))

		__ClearPageSwapBacked(page);

	/*

	 * For now, we report if PG_reserved was found set, but do not

	 * clear it, and do not free the page.  But we shall soon need

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