block: implement request_queue->dma_drain_needed
[linux-2.6.git] / block / blk-settings.c
index 13536a3..9a8ffdd 100644 (file)
@@ -296,6 +296,7 @@ EXPORT_SYMBOL(blk_queue_stack_limits);
  * blk_queue_dma_drain - Set up a drain buffer for excess dma.
  *
  * @q:  the request queue for the device
+ * @dma_drain_needed: fn which returns non-zero if drain is necessary
  * @buf:       physically contiguous buffer
  * @size:      size of the buffer in bytes
  *
@@ -315,14 +316,16 @@ EXPORT_SYMBOL(blk_queue_stack_limits);
  * device can support otherwise there won't be room for the drain
  * buffer.
  */
-int blk_queue_dma_drain(struct request_queue *q, void *buf,
-                               unsigned int size)
+extern int blk_queue_dma_drain(struct request_queue *q,
+                              dma_drain_needed_fn *dma_drain_needed,
+                              void *buf, unsigned int size)
 {
        if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
                return -EINVAL;
        /* make room for appending the drain */
        --q->max_hw_segments;
        --q->max_phys_segments;
+       q->dma_drain_needed = dma_drain_needed;
        q->dma_drain_buffer = buf;
        q->dma_drain_size = size;