From: Liu Bo <liubo2009@cn.fujitsu.com>
Date: Thu, 26 Jan 2012 20:01:12 +0000 (-0500)
Subject: Btrfs: do not defrag a file partially
X-Git-Tag: v3.12-rc1~3717^2~30
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7ec31b548a17f773ab6289e795ed3a6820e8b56e;p=kernel%2Fkernel-generic.git

Btrfs: do not defrag a file partially

xfstests 218 complains that btrfs defrags a file partially:
 After: 1
 Write backwards sync, but contiguous - should defrag to 1 extent
 Before: 10
-After: 1
+After: 2

To fix this, we need to set max_to_defrag count properly.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6834be4..0b06a5c 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1066,7 +1066,7 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 		i = range->start >> PAGE_CACHE_SHIFT;
 	}
 	if (!max_to_defrag)
-		max_to_defrag = last_index;
+		max_to_defrag = last_index + 1;
 
 	/*
 	 * make writeback starts from i, so the defrag range can be