linux-ext4 - Re: [PATCH] ext4: mballoc avoid use root reserved blocks for non root allocation

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Date:	Thu, 5 Jun 2008 22:33:45 -0400
From:	Theodore Tso <tytso@....EDU>
To:	Mingming Cao <cmm@...ibm.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: mballoc avoid use root reserved blocks for non
	root allocation

On Sun, Jun 01, 2008 at 02:06:53PM -0700, Mingming Cao wrote:
> ext4: mballoc avoid use root reserved blocks for non root allocation
> 
> From: Mingming Cao <cmm@...ibm.com>
> 
> mballoc allocation missed check for blocks reserved for root users. Add
> ext4_has_free_blocks() check before allocation. Also modified
> ext4_has_free_blocks() to support multiple block allocation request.

This was discovered by a Gentoo user who tried compiling on a UP system.....

> Index: linux-2.6.26-rc4/fs/ext4/balloc.c
> ....
> +	if (free_blocks - root_blocks < FBC_BATCH)
> +		free_blocks =
> +			percpu_counter_sum_positive(&sbi->s_freeblocks_counter);


FBC_BATCH is only defined if CONFIG_SMP is defined.  I believe the
simplest fix is surround the above if statement with an "#ifdef
CONFIG_SMP", since on UP systems, the percpu counters are always
exactly correct.

					- Ted
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