linux-kernel - Re: [PATCH 11/16] f2fs: add inode operations for special inodes

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Message-Id: <E4F29864-3D97-4839-BC4E-6DCFDAC5447C@dubeyko.com>
Date:	Sun, 14 Oct 2012 02:21:42 +0400
From:	Vyacheslav Dubeyko <slava@...eyko.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	김재극 <jaegeuk.kim@...sung.com>,
	viro@...iv.linux.org.uk, "'Theodore Ts'o'" <tytso@....edu>,
	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	chur.lee@...sung.com, cm224.lee@...sung.com,
	jooyoung.hwang@...sung.com
Subject: Re: [PATCH 11/16] f2fs: add inode operations for special inodes


On Oct 14, 2012, at 12:52 AM, Arnd Bergmann wrote:

> On Friday 05 October 2012, 김재극 wrote:
>> +const char *media_ext_lists[] = {
>> +       "jpg",
>> +       "gif",
>> +       "png",
>> +       "avi",
>> +       "divx",
>> +       "mp4",
>> +       "mp3",
>> ...
> 
>> + * Set multimedia files as cold files for hot/cold data separation
>> + */
>> +static inline void set_cold_file(struct inode *inode, const unsigned char *name)
>> +{
>> +       const char **extlist = media_ext_lists;
>> +
>> +       while (*extlist) {
>> +               if (!is_multimedia_file(name, *extlist)) {
>> +                       F2FS_I(inode)->is_cold = 1;
>> +                       break;
>> +               }
>> +               extlist++;
>> +       }
>> +}
> 
> This is a very clever way of categorizing files by their name, but I wonder if hardcoding
> the list of file name extensions at in the kernel source is the best strategy. Generally
> I would consider this to be a policy that should be configurable by the user.
> 
> Unfortunately I can't think of a good interface to configure this, but maybe someone
> else has a useful idea. Maybe the list can be stored in the superblock and get written
> at mkfs time from the same defaults, but with the option of overriding it using
> a debugfs tool.
> 

By the way, how about extended attributes? It is possible to save in extended attribute a hint about file's content nature during creation operation or later. Moreover, extended attribute gives possibility to change hint after renaming operation, for example.

With the best regards,
Vyacheslav Dubeyko.

> 	Arnd
> --
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