From: Alexander V. Lukyanov <lav@netis.ru>
Date: Tue, 22 Feb 2011 02:33:21 +0000 (-0500)
Subject: ext4: allow inode_readahead_blks=0 (linux-2.6.37)
X-Git-Tag: v2.6.39-rc1~73^2~39
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5dbd571d875d73e087c1eeb3d840cfc653a97422;p=pandora-kernel.git

ext4: allow inode_readahead_blks=0 (linux-2.6.37)

I cannot disable inode-read-ahead feature of ext4 (on 2.6.37):

# echo 0 > /sys/fs/ext4/sda2/inode_readahead_blks
bash: echo: write error: Invalid argument

On a server with lots of small files and random access this read-ahead makes
performance worse, and I'd like to disable it. I work around this problem
by using value of 1, but it still reads an extra block.

This patch fixes the problem by checking for zero explicitly.

Signed-off-by: Alexander V. Lukyanov <lav@netis.ru>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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