From patchwork Wed Dec 16 17:55:43 2009
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Date: Wed, 16 Dec 2009 09:55:43 -0800 (PST)
From: Sage Weil <sage@newdream.net>
To: Li Dongyang <jerry87905@gmail.com>
cc: linux-btrfs@vger.kernel.org
Subject: Re: cp --reflink with Btrfs
In-Reply-To: <4b287dd5.5744f10a.3536.2011@mx.google.com>
Message-ID: <Pine.LNX.4.64.0912160943280.2801@cobra.newdream.net>
References: <hg1cge$74i$1@ger.gmane.org>
	<20091214162323.GA2165@localhost.localdomain>
	<hg96k6$q17$1@ger.gmane.org>
	<4b287dd5.5744f10a.3536.2011@mx.google.com>
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diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index cdbb054..1a964a4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -994,8 +994,11 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 	}
 
 	/* determine range to clone */
+	ret = 0;
+	if (off == src->i_size && len == 0)
+		goto out_unlock;
 	ret = -EINVAL;
-	if (off >= src->i_size || off + len > src->i_size)
+	if (off > src->i_size || off + len > src->i_size)
 		goto out_unlock;
 	if (len == 0)
 		olen = len = src->i_size - off;