1 files changed, 29 insertions, 0 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 44e20e578ba0..b306265caa33 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -1778,6 +1778,35 @@ xfs_buf_delwri_dequeue(
         trace_xfs_buf_delwri_dequeue(bp, _RET_IP_);
 }
 
+/*
+ * If a delwri buffer needs to be pushed before it has aged out, then promote
+ * it to the head of the delwri queue so that it will be flushed on the next
+ * xfsbufd run. We do this by resetting the queuetime of the buffer to be older
+ * than the age currently needed to flush the buffer. Hence the next time the
+ * xfsbufd sees it is guaranteed to be considered old enough to flush.
+ */
+void
+xfs_buf_delwri_promote(
+        struct xfs_buf  *bp)
+{
+        struct xfs_buftarg *btp = bp->b_target;
+        long            age = xfs_buf_age_centisecs * msecs_to_jiffies(10) + 1;
+
+        ASSERT(bp->b_flags & XBF_DELWRI);
+        ASSERT(bp->b_flags & _XBF_DELWRI_Q);
+
+        /*
+         * Check the buffer age before locking the delayed write queue as we
+         * don't need to promote buffers that are already past the flush age.
+         */
+        if (bp->b_queuetime < jiffies - age)
+                return;
+        bp->b_queuetime = jiffies - age;
+        spin_lock(&btp->bt_delwrite_lock);
+        list_move(&bp->b_list, &btp->bt_delwrite_queue);
+        spin_unlock(&btp->bt_delwrite_lock);
+}
+
 STATIC void
 xfs_buf_runall_queues(
         struct workqueue_struct *queue)