From 73ae2e3718e20b60a2a2b3050ba5d333e8e1a8f7 Mon Sep 17 00:00:00 2001
From: Tristan Ye <tristan.ye@oracle.com>
Date: Fri, 18 Mar 2011 14:35:40 +0800
Subject: [PATCH] --- yaml --- r: 251812 b: refs/heads/master c:
 ee16cc037e255801892481a2d0b7c1fff2adf1aa h: refs/heads/master v: v3

---
 [refs]                        |  2 +-
 trunk/fs/ocfs2/move_extents.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index f465512c20b6..65e44c8ec141 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e08477176d5575493ba4c30041245c34f2737ad4
+refs/heads/master: ee16cc037e255801892481a2d0b7c1fff2adf1aa
diff --git a/trunk/fs/ocfs2/move_extents.c b/trunk/fs/ocfs2/move_extents.c
index ae15c998a82a..1c822e08fea0 100644
--- a/trunk/fs/ocfs2/move_extents.c
+++ b/trunk/fs/ocfs2/move_extents.c
@@ -797,3 +797,33 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
 
 	return ret;
 }
+
+/*
+ * Helper to calculate the defraging length in one run according to threshold.
+ */
+static void ocfs2_calc_extent_defrag_len(u32 *alloc_size, u32 *len_defraged,
+					 u32 threshold, int *skip)
+{
+	if ((*alloc_size + *len_defraged) < threshold) {
+		/*
+		 * proceed defragmentation until we meet the thresh
+		 */
+		*len_defraged += *alloc_size;
+	} else if (*len_defraged == 0) {
+		/*
+		 * XXX: skip a large extent.
+		 */
+		*skip = 1;
+	} else {
+		/*
+		 * split this extent to coalesce with former pieces as
+		 * to reach the threshold.
+		 *
+		 * we're done here with one cycle of defragmentation
+		 * in a size of 'thresh', resetting 'len_defraged'
+		 * forces a new defragmentation.
+		 */
+		*alloc_size = threshold - *len_defraged;
+		*len_defraged = 0;
+	}
+}