linux-kernel - Re: [PATCH RESEND] udf: extent cache implementation for manipulating block map

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Date:	Wed, 22 Aug 2012 19:27:40 +0900
From:	Namjae Jeon <linkinjeon@...il.com>
To:	Jan Kara <jack@...e.cz>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Ashish Sangwan <a.sangwan@...sung.com>,
	Bonggil Bak <bgbak@...sung.com>
Subject: Re: [PATCH RESEND] udf: extent cache implementation for manipulating
 block map

2012/8/22, Jan Kara <jack@...e.cz>:
> On Wed 22-08-12 19:02:26, Namjae Jeon wrote:
>> 2012/8/21, Jan Kara <jack@...e.cz>:
>> Hi. Jan.
>> Okay, We are trying to do it from your comment.
>> 1. Change udf_ext_cache structure to following which would also include
>> *bh.
>> struct udf_ext_cache {
>>
>> /* Position of the cached extent */
>> struct extent_position epos;
>>
>> /* Logical block where cached extent starts */
>> sector_t block;
>> };
>   OK.
>
>> 2. Remove call to brelse(epos.bh) from all the callers of inode_bmap()
>> and move it to udf_evict_inode()
>   It might be easier to keep brelse() where it is and add get_bh() to
> udf_add_extent_cache() and brelse() to udf_clear_extent_cache(). It is then
> easier to audit we don't leak bh references...
Good point. I will~
>
>> 3. As now we are not caching elen, etype and eloc, we have to change
>> the cache_hit logic in inode_bmap.
>> The call to function udf_next_aext is now necessary from inode_bmap.
>   Yes.
>
>> 4. Remove call to udf_clear_extent_cache() from udf_get_block as with
>> new scheme, it is not required.
>   You still need this when you write before the cached location (e.g. when
> the file has holes, and you write into them, extents will shift).
Okay, I see.
I will send v2 patch soon.
Thanks for your advice.
>
>
> 								Honza
> --
> Jan Kara <jack@...e.cz>
> SUSE Labs, CR
>
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