From: Andreas Dilger <adilger@clusterfs.com>
Subject: Re: [PATCH 0/3] readahead drop behind and size adjustment
Date: Tue, 24 Jul 2007 02:50:56 -0600
Message-ID: <20070724085056.GE5992@schatzie.adilger.int>
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Cc: Fengguang Wu <fengguang.wu@gmail.com>,
	Nick Piggin <nickpiggin@yahoo.com.au>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Dave Jones <davej@redhat.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	riel <riel@redhat.com>, Tim Pepper <lnxninja@us.ibm.com>,
	Chris Snook <csnook@redhat.com>,
	Jens Axboe <jens.axboe@oracle.com>, linux-ext4@vger.kernel.org,
	Mingming Cao <cmm@us.ibm.com>,
	Bjorn Helgaas <bjorn.helgaas@hp.com>,
	Chris Ahna <christopher.j.ahna@intel.com>,
	David Mosberger-Tang <davidm@hpl.hp.com>,
	Kyle McMartin <kyle@parisc-linux.org>,
	Dave Jones <davej@codemonkey.org.uk>,
	Dave Airlie <airlied@linux.ie>
To: Andrew Morton <akpm@linux-foundation.org>
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On Jul 23, 2007  18:17 -0700, Andrew Morton wrote:
> hm, yes, there is a risk that the code was accidentally correct.  Or the
> code has only ever dealt with power-of-2 inputs, in which case it happens
> to work either way.
> 
> David(s) and ext4-people: could we please have a close review of these
> changes?
> > @@ -1706,8 +1704,8 @@ static int ext4_fill_super (struct super
> > -	sbi->s_addr_per_block_bits = log2(EXT4_ADDR_PER_BLOCK(sb));
> > -	sbi->s_desc_per_block_bits = log2(EXT4_DESC_PER_BLOCK(sb));
> > +	sbi->s_addr_per_block_bits = ilog2(EXT4_ADDR_PER_BLOCK(sb));
> > +	sbi->s_desc_per_block_bits = ilog2(EXT4_DESC_PER_BLOCK(sb));

For the ext[234] code there has only ever been power-of-two values for
ADDR_PER_BLOCK() and DESC_PER_BLOCK().

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.