Merge branch 'audit.b37' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit...

[sfrench/cifs-2.6.git] / mm / truncate.c

diff --git a/mm/truncate.c b/mm/truncate.c
index ecdfdcc50522976b88d307e0123f15ca771b2c5e..ebf3fcb4115b8c664e54e4c47e02968ed93ab0be 100644 (file)
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -51,15 +51,22 @@ 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)) {
                struct address_space *mapping = page->mapping;
                if (mapping && mapping_cap_account_dirty(mapping)) {
@@ -78,7 +85,7 @@ EXPORT_SYMBOL(cancel_dirty_page);
  *
  * We need to bale out if page->mapping is no longer equal to the original
  * mapping.  This happens a) when the VM reclaimed the page while we waited on
- * its lock, b) when a concurrent invalidate_inode_pages got there first and
+ * its lock, b) when a concurrent invalidate_mapping_pages got there first and
  * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
  */
 static void
@@ -99,7 +106,7 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
 }
 
 /*
- * This is for invalidate_inode_pages().  That function can be called at
+ * This is for invalidate_mapping_pages().  That function can be called at
  * any time, and is not supposed to throw away dirty pages.  But pages can
  * be marked dirty at any time too, so use remove_mapping which safely
  * discards clean, unused pages.
@@ -303,12 +310,7 @@ unlock:
        }
        return ret;
 }
-
-unsigned long invalidate_inode_pages(struct address_space *mapping)
-{
-       return invalidate_mapping_pages(mapping, 0, ~0UL);
-}
-EXPORT_SYMBOL(invalidate_inode_pages);
+EXPORT_SYMBOL(invalidate_mapping_pages);
 
 /*
  * This is like invalidate_complete_page(), except it ignores the page's
@@ -341,6 +343,15 @@ 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
@@ -405,14 +416,14 @@ 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);