1 files changed, 40 insertions, 9 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
index 9bfb8e853860..5df947de7654 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -52,6 +52,33 @@ static inline void truncate_partial_page(struct page *page, unsigned partial)
 }
 
 /*
+ * 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"? Tought you could.
+ */
+void cancel_dirty_page(struct page *page, unsigned int account_size)
+{
+        if (TestClearPageDirty(page)) {
+                struct address_space *mapping = page->mapping;
+                if (mapping && mapping_cap_account_dirty(mapping)) {
+                        dec_zone_page_state(page, NR_FILE_DIRTY);
+                        if (account_size)
+                                task_io_account_cancelled_write(account_size);
+                }
+        }
+}
+EXPORT_SYMBOL(cancel_dirty_page);
+
+/*
  * If truncate cannot remove the fs-private metadata from the page, the page
  * becomes anonymous.  It will be left on the LRU and may even be mapped into
  * user pagetables if we're racing with filemap_nopage().
@@ -67,11 +94,11 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
         if (page->mapping != mapping)
                 return;
 
+        cancel_dirty_page(page, PAGE_CACHE_SIZE);
+
         if (PagePrivate(page))
                 do_invalidatepage(page, 0);
 
-        if (test_clear_page_dirty(page))
-                task_io_account_cancelled_write(PAGE_CACHE_SIZE);
         ClearPageUptodate(page);
         ClearPageMappedToDisk(page);
         remove_from_page_cache(page);
@@ -321,6 +348,15 @@ failed:
         return 0;
 }
 
+static int do_launder_page(struct address_space *mapping, struct page *page)
+{
+        if (!PageDirty(page))
+                return 0;
+        if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
+                return 0;
+        return mapping->a_ops->launder_page(page);
+}
+
 /**
  * invalidate_inode_pages2_range - remove range of pages from an address_space
  * @mapping: the address_space
@@ -350,7 +386,6 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                 for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
                         struct page *page = pvec.pages[i];
                         pgoff_t page_index;
-                        int was_dirty;
 
                         lock_page(page);
                         if (page->mapping != mapping) {
@@ -386,18 +421,14 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                                           PAGE_CACHE_SIZE, 0);
                                 }
                         }
-                        was_dirty = test_clear_page_dirty(page);
-                        if (!invalidate_complete_page2(mapping, page)) {
-                                if (was_dirty)
-                                        set_page_dirty(page);
+                        ret = do_launder_page(mapping, page);
+                        if (ret == 0 && !invalidate_complete_page2(mapping, page))
                                 ret = -EIO;
-                        }
                         unlock_page(page);
                 }
                 pagevec_release(&pvec);
                 cond_resched();
         }
-        WARN_ON_ONCE(ret);
         return ret;
 }
 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);