HWPOISON: Add invalidate_inode_page

Add a simple way to invalidate a single page
This is just a refactoring of the truncate.c code.
Originally from Fengguang, modified by Andi Kleen.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 20 insertions, 6 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
index 2519a7c92873..ea132f7ea2d2 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -146,6 +146,24 @@ int truncate_inode_page(struct address_space *mapping, struct page *page)
         return truncate_complete_page(mapping, page);
 }
 
+/*
+ * Safely invalidate one page from its pagecache mapping.
+ * It only drops clean, unused pages. The page must be locked.
+ *
+ * Returns 1 if the page is successfully invalidated, otherwise 0.
+ */
+int invalidate_inode_page(struct page *page)
+{
+        struct address_space *mapping = page_mapping(page);
+        if (!mapping)
+                return 0;
+        if (PageDirty(page) || PageWriteback(page))
+                return 0;
+        if (page_mapped(page))
+                return 0;
+        return invalidate_complete_page(mapping, page);
+}
+
 /**
  * truncate_inode_pages - truncate range of pages specified by start & end byte offsets
  * @mapping: mapping to truncate
@@ -312,12 +330,8 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
                         if (lock_failed)
                                 continue;
 
-                        if (PageDirty(page) || PageWriteback(page))
-                                goto unlock;
-                        if (page_mapped(page))
-                                goto unlock;
-                        ret += invalidate_complete_page(mapping, page);
-unlock:
+                        ret += invalidate_inode_page(page);
+
                         unlock_page(page);
                         if (next > end)
                                 break;