From d77815461f047e561f77a07754ae923ade597d4e Mon Sep 17 00:00:00 2001
From: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: Fri, 30 May 2014 15:16:10 +0800
Subject: [PATCH] btrfs: Avoid trucating page or punching hole in a already
 existed hole.

btrfs_punch_hole() will truncate unaligned pages or punch hole on a
already existed hole.
This will cause unneeded zero page or holes splitting the original huge
hole.

This patch will skip already existed holes before any page truncating or
hole punching.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
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Reading git-format-patch failed