Merge ../linux-2.6-watchdog-mm

[pandora-kernel.git] / mm / truncate.c

diff --git a/mm/truncate.c b/mm/truncate.c
index 4a38dd1..5df947d 100644 (file)
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -51,21 +51,32 @@ static inline void truncate_partial_page(struct page *page, unsigned partial)
                do_invalidatepage(page, 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 we're cancelling the page, it had better not be mapped any more */
-       if (page_mapped(page)) {
-               static unsigned int warncount;
-
-               WARN_ON(++warncount < 5);
-       }
-               
-       if (TestClearPageDirty(page) && account_size &&
-                       mapping_cap_account_dirty(page->mapping)) {
-               dec_zone_page_state(page, NR_FILE_DIRTY);
-               task_io_account_cancelled_write(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
@@ -337,6 +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
@@ -401,14 +421,14 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                                          PAGE_CACHE_SIZE, 0);
                                }
                        }
-                       if (!invalidate_complete_page2(mapping, 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);