From: Robin Dong <hao.bigrat@gmail.com>
Date: Mon, 18 Jul 2011 03:27:43 +0000 (-0400)
Subject: ext4: avoid wasted extent cache lookup if !PUNCH_OUT_EXT
X-Git-Tag: v3.1-rc1~90^2~30
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=015861badd0db43d025bbb538f8fc62dfaf3f18d;p=pandora-kernel.git

ext4: avoid wasted extent cache lookup if !PUNCH_OUT_EXT

This patch avoids an extraneous lookup of the extent cache
in ext4_ext_map_blocks() when the flag
EXT4_GET_BLOCKS_PUNCH_OUT_EXT is absent.

The existing logic was performing the lookup but not making
use of the result. The patch simply reverses the order of evaluation
in the condition.

Since ext4_ext_in_cache() does not initialize newex on misses, bypassing
its invocation does not introduce any new issue in this regard.

Signed-off-by: Robin Dong <sanbai@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Eric Gouriou <egouriou@google.com>
---

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