linux-kernel - RE:(2) [f2fs-dev] [RFC PATCH] f2fs: add support single node section mode

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Message-ID: <20240610031547epcms2p526560bc9d2fd3a5f36615fe645640079@epcms2p5>
Date: Mon, 10 Jun 2024 12:15:47 +0900
From: Daejun Park <daejun7.park@...sung.com>
To: Yongpeng Yang <yangyongpeng1@...o.com>, "jaegeuk@...nel.org"
	<jaegeuk@...nel.org>, "chao@...nel.org" <chao@...nel.org>, "corbet@....net"
	<corbet@....net>, "linux-f2fs-devel@...ts.sourceforge.net"
	<linux-f2fs-devel@...ts.sourceforge.net>, "linux-doc@...r.kernel.org"
	<linux-doc@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: Nayeon Kim <nayeoni.kim@...sung.com>, Siwoo Jung <siu.jung@...sung.com>,
	Seokhwan Kim <sukka.kim@...sung.com>, Dongjin Kim
	<dongjin_.kim@...sung.com>, Daejun Park <daejun7.park@...sung.com>
Subject: RE:(2) [f2fs-dev] [RFC PATCH] f2fs: add support single node section
 mode

> Hi Daejun,
> 1. It is not compatible with "F2FS_OPTION(sbi).active_logs == 2".
> 2. Once has_enough_free_secs is false, F2FS cannot restore to multi-node
> sections even after has_enough_free_secs becomes true and the filesystem
> is unmounted and remounted. This seems unreasonable.

Hi Yongpeng Yang,

1. Yes, I will modify it so that it only applies when active_log is 6.
2. This technique is effective when utilization is high. Therefore, in my scenario, I assumed that only heavy users would use this option. So I assumed that the free section would not be sufficiently secured even after that.
Futhermore, if a new section is allocated to deactivate a single node whenever there is free space, then soon again insufficient free space may occur, resulting in more unnecessary GC.

Thanks,
Daejun