Call elv_kick_page() to notify the elevator of a pending read.

Requests of priority IOPRIO_CLASS_IDLE are ignored.

Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---


--- linux-2.6.17-rc5-mm3.orig/block/ll_rw_blk.c
+++ linux-2.6.17-rc5-mm3/block/ll_rw_blk.c
@@ -1619,6 +1619,9 @@ static void blk_backing_dev_unplug(struc
 {
 	request_queue_t *q = bdi->unplug_io_data;
 
+	if (IOPRIO_PRIO_CLASS(current->ioprio) != IOPRIO_CLASS_IDLE)
+		elv_kick_page(q, page);
+
 	/*
 	 * devices don't necessarily have an ->unplug_fn defined
 	 */
--- linux-2.6.17-rc5-mm3.orig/fs/buffer.c
+++ linux-2.6.17-rc5-mm3/fs/buffer.c
@@ -63,8 +63,9 @@ static int sync_buffer(void *word)
 
 	smp_mb();
 	bd = bh->b_bdev;
-	if (bd)
-		blk_run_address_space(bd->bd_inode->i_mapping);
+	if (bd && bd->bd_inode && bd->bd_inode->i_mapping)
+		blk_run_backing_dev(bd->bd_inode->i_mapping->backing_dev_info,
+					bh->b_page);
 	io_schedule();
 	return 0;
 }

--