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authorRik van Riel <riel@redhat.com>2008-10-18 20:26:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-20 08:50:25 -0700
commitb2e185384f534781fd22f5ce170b2ad26f97df70 (patch)
tree3096b8250302c5a9f71b1b5122345f7cf62606cc /include/linux/mm_inline.h
parent68a22394c286a2daf06ee8d65d8835f738faefa5 (diff)
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: Rik van Riel <riel@redhat.com> Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: MinChan Kim <minchan.kim@gmail.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/mm_inline.h')
-rw-r--r--include/linux/mm_inline.h27
1 files changed, 27 insertions, 0 deletions
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 2704729777e..96e970485b6 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -1,3 +1,28 @@
+#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