diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index feaa82f..9b3ceac 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1209,10 +1209,10 @@ static void ext4_da_page_release_reservation(struct page *page,
 	do {
 		unsigned int next_off = curr_off + bh->b_size;
 
-		if ((offset <= curr_off) && (buffer_delay(bh))) {
+		if ((offset <= curr_off) && buffer_delay(bh) &&
+				!buffer_da_mapped(bh)) {
 			to_release++;
 			clear_buffer_delay(bh);
-			clear_buffer_da_mapped(bh);
 		}
 		curr_off = next_off;
 	} while ((bh = bh->b_this_page) != head);
@@ -2544,6 +2544,7 @@ static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
 	 * Drop reserved blocks
 	 */
 	BUG_ON(!PageLocked(page));
+	down_write(&EXT4_I(page->mapping->host)->i_data_sem);
 	if (!page_has_buffers(page))
 		goto out;
 
@@ -2552,6 +2553,7 @@ static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
 out:
 	ext4_invalidatepage(page, offset);
 
+	up_write(&EXT4_I(page->mapping->host)->i_data_sem);
 	return;
 }