1 files changed, 52 insertions, 3 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index d2a4d1bb2d57..4d7433534f5c 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -83,6 +83,40 @@ void unlock_buffer(struct buffer_head *bh)
 EXPORT_SYMBOL(unlock_buffer);
 
 /*
+ * Returns if the page has dirty or writeback buffers. If all the buffers
+ * are unlocked and clean then the PageDirty information is stale. If
+ * any of the pages are locked, it is assumed they are locked for IO.
+ */
+void buffer_check_dirty_writeback(struct page *page,
+                                     bool *dirty, bool *writeback)
+{
+        struct buffer_head *head, *bh;
+        *dirty = false;
+        *writeback = false;
+
+        BUG_ON(!PageLocked(page));
+
+        if (!page_has_buffers(page))
+                return;
+
+        if (PageWriteback(page))
+                *writeback = true;
+
+        head = page_buffers(page);
+        bh = head;
+        do {
+                if (buffer_locked(bh))
+                        *writeback = true;
+
+                if (buffer_dirty(bh))
+                        *dirty = true;
+
+                bh = bh->b_this_page;
+        } while (bh != head);
+}
+EXPORT_SYMBOL(buffer_check_dirty_writeback);
+
+/*
  * Block until a buffer comes unlocked.  This doesn't stop it
  * from becoming locked again - you have to lock it yourself
  * if you want to preserve its state.
@@ -1454,7 +1488,8 @@ static void discard_buffer(struct buffer_head * bh)
  * block_invalidatepage - invalidate part or all of a buffer-backed page
  *
  * @page: the page which is affected
- * @offset: the index of the truncation point
+ * @offset: start of the range to invalidate
+ * @length: length of the range to invalidate
  *
  * block_invalidatepage() is called when all or part of the page has become
  * invalidated by a truncate operation.
@@ -1465,15 +1500,22 @@ static void discard_buffer(struct buffer_head * bh)
  * point.  Because the caller is about to free (and possibly reuse) those
  * blocks on-disk.
  */
-void block_invalidatepage(struct page *page, unsigned long offset)
+void block_invalidatepage(struct page *page, unsigned int offset,
+                          unsigned int length)
 {
         struct buffer_head *head, *bh, *next;
         unsigned int curr_off = 0;
+        unsigned int stop = length + offset;
 
         BUG_ON(!PageLocked(page));
         if (!page_has_buffers(page))
                 goto out;
 
+        /*
+         * Check for overflow
+         */
+        BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
+
         head = page_buffers(page);
         bh = head;
         do {
@@ -1481,6 +1523,12 @@ void block_invalidatepage(struct page *page, unsigned long offset)
                 next = bh->b_this_page;
 
                 /*
+                 * Are we still fully in range ?
+                 */
+                if (next_off > stop)
+                        goto out;
+
+                /*
                  * is this block fully invalidated?
                  */
                 if (offset <= curr_off)
@@ -1501,6 +1549,7 @@ out:
 }
 EXPORT_SYMBOL(block_invalidatepage);
 
+
 /*
  * We attach and possibly dirty the buffers atomically wrt
  * __set_page_dirty_buffers() via private_lock.  try_to_free_buffers
@@ -2841,7 +2890,7 @@ int block_write_full_page_endio(struct page *page, get_block_t *get_block,
                  * they may have been added in ext3_writepage().  Make them
                  * freeable here, so the page does not leak.
                  */
-                do_invalidatepage(page, 0);
+                do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
                 unlock_page(page);
                 return 0; /* don't care */
         }