From: Akira Fujita <a-fujita@rs.jp.nec.com>
Subject: Re: [PATCH 1/5] ext4 online defrag header file changes
Date: Mon, 17 Mar 2008 15:28:29 +0900
Message-ID: <47DE0F8D.2060106@rs.jp.nec.com>
References: <200803141202.AA00330@TNESG9526.rs.jp.nec.com> <20080314125848.GE3542@webber.adilger.int>
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Cc: cmm@us.ibm.com, tytso@mit.edu, linux-ext4@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
To: Andreas Dilger <adilger@sun.com>
In-Reply-To: <20080314125848.GE3542@webber.adilger.int>
Sender: linux-ext4-owner@vger.kernel.org

Hi Andreas,
>> How about renaming this structure from ext4_extent_data to
>> ext4_extent_info which used the extent in-core structure
>> and put it into ext4_fs_extents.h? 
>> Because in-core super_block is ext4_sb_info.
>>
>> /*
>>  * This is the extent in-core structure.
>>  */
>> struct ext4_extent_info {
>> 	ext4_lblk_t	ee_block;	/* first logical block extent covers */
>> 	int		ee_len;		/* number of blocks covered by extent */
>> 	ext4_fsblk_t	ee_start;	/* first physical block extent covers */
>> };      
>>     
>
> Would it be possible to use the FIEMAP interface to get the file mapping
> data to userspace?  That would avoid the need to have a second ioctl
> with nearly the same data.
>   
Reducing ioctl makes sense.
But EXT4_EXTENTS_INFO needs to get the file mapping data
with inode number not file name.
So we should keep ext4_extents_info structure
or put ino entry in fiemap structure.

Regards, Akira