From: Arnd Bergmann <arnd@arndb.de>
To: =?utf-8?q?=EA=B9=80=EC=9E=AC=EA=B7=B9?= <jaegeuk.kim@samsung.com>
Subject: Re: [PATCH 11/16] f2fs: add inode operations for special inodes
Date: Sat, 13 Oct 2012 20:52:09 +0000
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Cc: viro@zeniv.linux.org.uk, "'Theodore Ts'o'" <tytso@mit.edu>,
        gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
        chur.lee@samsung.com, cm224.lee@samsung.com,
        jooyoung.hwang@samsung.com
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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.

	Arnd
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