FS-Cache: Recruit a page flags for cache management
Recruit a page flag to aid in cache management. The following extra flag is
defined:
(1) PG_fscache (PG_private_2)
The marked page is backed by a local cache and is pinning resources in the
cache driver.
If PG_fscache is set, then things that checked for PG_private will now also
check for that. This includes things like truncation and page invalidation.
The function page_has_private() had been added to make the checks for both
PG_private and PG_private_2 at the same time.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
diff --git a/mm/migrate.c b/mm/migrate.c
index a9eff3f..068655d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -250,7 +250,7 @@
* The number of remaining references must be:
* 1 for anonymous pages without a mapping
* 2 for pages with a mapping
- * 3 for pages with a mapping and PagePrivate set.
+ * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
*/
static int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
@@ -270,7 +270,7 @@
pslot = radix_tree_lookup_slot(&mapping->page_tree,
page_index(page));
- expected_count = 2 + !!PagePrivate(page);
+ expected_count = 2 + !!page_has_private(page);
if (page_count(page) != expected_count ||
(struct page *)radix_tree_deref_slot(pslot) != page) {
spin_unlock_irq(&mapping->tree_lock);
@@ -386,7 +386,7 @@
/*
* Common logic to directly migrate a single page suitable for
- * pages that do not use PagePrivate.
+ * pages that do not use PagePrivate/PagePrivate2.
*
* Pages are locked upon entry and exit.
*/
@@ -522,7 +522,7 @@
* Buffers may be managed in a filesystem specific way.
* We must have no buffers or drop them.
*/
- if (PagePrivate(page) &&
+ if (page_has_private(page) &&
!try_to_release_page(page, GFP_KERNEL))
return -EAGAIN;
@@ -655,7 +655,7 @@
* free the metadata, so the page can be freed.
*/
if (!page->mapping) {
- if (!PageAnon(page) && PagePrivate(page)) {
+ if (!PageAnon(page) && page_has_private(page)) {
/*
* Go direct to try_to_free_buffers() here because
* a) that's what try_to_release_page() would do anyway
