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>

1 files changed, 5 insertions, 5 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
index 1229211104f8..55206fab7b99 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -50,7 +50,7 @@ void do_invalidatepage(struct page *page, unsigned long offset)
 static inline void truncate_partial_page(struct page *page, unsigned partial)
 {
         zero_user_segment(page, partial, PAGE_CACHE_SIZE);
-        if (PagePrivate(page))
+        if (page_has_private(page))
                 do_invalidatepage(page, partial);
 }
 
@@ -99,7 +99,7 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
         if (page->mapping != mapping)
                 return;
 
-        if (PagePrivate(page))
+        if (page_has_private(page))
                 do_invalidatepage(page, 0);
 
         cancel_dirty_page(page, PAGE_CACHE_SIZE);
@@ -126,7 +126,7 @@ invalidate_complete_page(struct address_space *mapping, struct page *page)
         if (page->mapping != mapping)
                 return 0;
 
-        if (PagePrivate(page) && !try_to_release_page(page, 0))
+        if (page_has_private(page) && !try_to_release_page(page, 0))
                 return 0;
 
         clear_page_mlock(page);
@@ -348,7 +348,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
         if (page->mapping != mapping)
                 return 0;
 
-        if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
+        if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
                 return 0;
 
         spin_lock_irq(&mapping->tree_lock);
@@ -356,7 +356,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
                 goto failed;
 
         clear_page_mlock(page);
-        BUG_ON(PagePrivate(page));
+        BUG_ON(page_has_private(page));
         __remove_from_page_cache(page);
         spin_unlock_irq(&mapping->tree_lock);
         page_cache_release(page);       /* pagecache ref */