5 files changed, 25 insertions, 15 deletions

diff --git a/drivers/staging/lustre/lustre/include/linux/lustre_patchless_compat.h b/drivers/staging/lustre/lustre/include/linux/lustre_patchless_compat.h
index d72605864b0a..14562788e4e0 100644
--- a/drivers/staging/lustre/lustre/include/linux/lustre_patchless_compat.h
+++ b/drivers/staging/lustre/lustre/include/linux/lustre_patchless_compat.h
@@ -55,9 +55,7 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
         if (PagePrivate(page))
                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_CACHE_SIZE);
 
-        if (TestClearPageDirty(page))
-                account_page_cleaned(page, mapping);
-
+        cancel_dirty_page(page);
         ClearPageMappedToDisk(page);
         ll_delete_from_page_cache(page);
 }
diff --git a/fs/buffer.c b/fs/buffer.c
index f96173ad62d9..f21327d1f673 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3232,8 +3232,8 @@ int try_to_free_buffers(struct page *page)
          * to synchronise against __set_page_dirty_buffers and prevent the
          * dirty bit from being lost.
          */
-        if (ret && TestClearPageDirty(page))
-                account_page_cleaned(page, mapping);
+        if (ret)
+                cancel_dirty_page(page);
         spin_unlock(&mapping->private_lock);
 out:
         if (buffers_to_free) {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0755b9fd03a7..a83cf3a6f78e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1215,6 +1215,7 @@ void account_page_dirtied(struct page *page, struct address_space *mapping);
 void account_page_cleaned(struct page *page, struct address_space *mapping);
 int set_page_dirty(struct page *page);
 int set_page_dirty_lock(struct page *page);
+void cancel_dirty_page(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
 
 int get_cmdline(struct task_struct *task, char *buffer, int buflen);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 5daf5568b9e1..227b867598e1 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2112,12 +2112,6 @@ EXPORT_SYMBOL(account_page_dirtied);
 
 /*
  * Helper function for deaccounting dirty page without writeback.
- *
- * Doing this should *normally* only ever be done when a page
- * is truncated, and is not actually mapped anywhere at all. However,
- * fs/buffer.c does this when it notices that somebody has cleaned
- * out all the buffers on a page without actually doing it through
- * the VM. Can you say "ext3 is horribly ugly"? Thought you could.
  */
 void account_page_cleaned(struct page *page, struct address_space *mapping)
 {
@@ -2127,7 +2121,6 @@ void account_page_cleaned(struct page *page, struct address_space *mapping)
                 task_io_account_cancelled_write(PAGE_CACHE_SIZE);
         }
 }
-EXPORT_SYMBOL(account_page_cleaned);
 
 /*
  * For address_spaces which do not use buffers.  Just tag the page as dirty in
@@ -2266,6 +2259,26 @@ int set_page_dirty_lock(struct page *page)
 EXPORT_SYMBOL(set_page_dirty_lock);
 
 /*
+ * This cancels just the dirty bit on the kernel page itself, it does NOT
+ * actually remove dirty bits on any mmap's that may be around. It also
+ * leaves the page tagged dirty, so any sync activity will still find it on
+ * the dirty lists, and in particular, clear_page_dirty_for_io() will still
+ * look at the dirty bits in the VM.
+ *
+ * Doing this should *normally* only ever be done when a page is truncated,
+ * and is not actually mapped anywhere at all. However, fs/buffer.c does
+ * this when it notices that somebody has cleaned out all the buffers on a
+ * page without actually doing it through the VM. Can you say "ext3 is
+ * horribly ugly"? Thought you could.
+ */
+void cancel_dirty_page(struct page *page)
+{
+        if (TestClearPageDirty(page))
+                account_page_cleaned(page, page_mapping(page));
+}
+EXPORT_SYMBOL(cancel_dirty_page);
+
+/*
  * Clear a page's dirty flag, while caring for dirty memory accounting.
  * Returns true if the page was previously dirty.
  *
diff --git a/mm/truncate.c b/mm/truncate.c
index 66af9031fae8..0c360259c085 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -116,9 +116,7 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
          * the VM has canceled the dirty bit (eg ext3 journaling).
          * Hence dirty accounting check is placed after invalidation.
          */
-        if (TestClearPageDirty(page))
-                account_page_cleaned(page, mapping);
-
+        cancel_dirty_page(page);
         ClearPageMappedToDisk(page);
         delete_from_page_cache(page);
         return 0;