linux-ext4 - Re: [PATCH 2/2] ext4: Make ext4_ext_find_extent fills ext

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Date:	Fri, 13 Jun 2008 13:40:03 +0800
From:	Shen Feng <shen@...fujitsu.com>
To:	cmm@...ibm.com
CC:	linux-ext4@...r.kernel.org, Theodore Tso <tytso@....EDU>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/2] ext4: Make ext4_ext_find_extent fills ext_path	completely



Mingming Cao Wrote:
> On Wed, 2008-06-11 at 13:55 +0800, Shen Feng wrote:
>> When pos=0 or depth, the fields of ext4_ext_path is not
>> completely filled.
>> This patch also removes some unnecessary code.
>>
> 
> I added this patch to the patch queue, unless somebody disagree.
> 
> Mingming
>> Signed-off-by: Shen Feng <shen@...fujitsu.com>
>> ---
>>  fs/ext4/extents.c |    4 ++--
>>  1 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>> index d4f76d7..ff609df 100644
>> --- a/fs/ext4/extents.c
>> +++ b/fs/ext4/extents.c
>> @@ -524,6 +524,7 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
>>  		alloc = 1;
>>  	}
>>  	path[0].p_hdr = eh;
>> +	path[0].p_bh = NULL;
>>
>>  	i = depth;
>>  	/* walk through the tree */
>> @@ -552,12 +553,11 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
>>  	}
>>
>>  	path[ppos].p_depth = i;
>> -	path[ppos].p_hdr = eh;
>> -	path[ppos].p_ext = NULL;
>>  	path[ppos].p_idx = NULL;
>>
>>  	/* find extent */
>>  	ext4_ext_binsearch(inode, path + ppos, block);
>> +	path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);

Today I tested the patch with bonnie++ and found that sometimes
path[ppos].p_ext may be NULL. This may cause kernel oops.

This is because ext4_ext_binsearch return directly when the leaf is empty.



>>
>>  	ext4_ext_show_path(inode, path);
>>
> 
> 
> 

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