linux-ext4 - Re: [PATCH RESEND] ext4: Fix kernel BUG at fs/ext4/mballoc.c:910!

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Message-Id: <1203011025.3637.9.camel@localhost.localdomain>
Date:	Thu, 14 Feb 2008 09:43:45 -0800
From:	Mingming Cao <cmm@...ibm.com>
To:	Valerie Clement <valerie.clement@...l.net>
Cc:	linux-ext4 <linux-ext4@...r.kernel.org>,
	Andreas Dilger <adilger@....com>,
	Aneesh Kumar <aneesh.kumar@...ux.vnet.ibm.com>
Subject: Re: [PATCH RESEND] ext4: Fix kernel BUG at fs/ext4/mballoc.c:910!

On Thu, 2008-02-14 at 17:35 +0100, Valerie Clement wrote:
> Fix kernel BUG at fs/ext4/mballoc.c:910!
> 
> From: Valerie Clement <valerie.clement@...l.net>
> 
> With the flex_bg feature enabled, a large file creation oopses the
> kernel.
> The BUG_ON is:
> 	BUG_ON(len >= EXT4_BLOCKS_PER_GROUP(sb));
> 
> As the allocation of the bitmaps and the inode table can be done
> outside the block group with flex_bg, this allows to allocate up to
> EXT4_BLOCKS_PER_GROUP blocks in a group.
> Depending on the group size and the block size, extents might be 
> larger than BLOCKS_PER_GROUP(); use EXT_INIT_MAX_LEN instead of 
> BLOCKS_PER_GROUP().
> 

Yep, I think using EXT_INIT_MAX_LEN is better.
Will add to the patch queue shortly.

Thanks,
Mingming
> This patch fixes the oops.
> 
> Signed-off-by: Valerie Clement <valerie.clement@...l.net>
> ---
> 
>  fs/ext4/mballoc.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index b0f84b4..ccc33e9 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -34,6 +34,7 @@
>  #include <linux/pagemap.h>
>  #include <linux/seq_file.h>
>  #include <linux/version.h>
> +#include <linux/ext4_fs_extents.h>
>  #include "group.h"
> 
>  /*
> @@ -907,7 +908,9 @@ static void ext4_mb_mark_free_simple(struct super_block *sb,
>  	unsigned short chunk;
>  	unsigned short border;
> 
> -	BUG_ON(len >= EXT4_BLOCKS_PER_GROUP(sb));
> +	BUG_ON(len > EXT4_HAS_INCOMPAT_FEATURE(sb,
> +			EXT4_FEATURE_INCOMPAT_FLEX_BG) ? EXT_INIT_MAX_LEN :
> +			EXT4_BLOCKS_PER_GROUP(sb));
> 
>  	border = 2 << sb->s_blocksize_bits;
> 
> 
> 
> -
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