linux-kernel - Re: [f2fs-dev] [PATCH 3/3 v2] f2fs: keep dirty inodes selectively for checkpoint

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Message-ID: <20161105070238.GB10986@jaegeuk>
Date:   Sat, 5 Nov 2016 00:02:38 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 3/3 v2] f2fs: keep dirty inodes selectively
 for checkpoint

On Sat, Nov 05, 2016 at 10:44:07AM +0800, Chao Yu wrote:
> On 2016/10/20 10:26, Jaegeuk Kim wrote:
> > Change log from v1:
> >  o avoid performance regression
> > 
> >>From b34a3d3c4c3fa2d6e000acc99bc5216a247bd6cb Mon Sep 17 00:00:00 2001
> > From: Jaegeuk Kim <jaegeuk@...nel.org>
> > Date: Fri, 14 Oct 2016 11:51:23 -0700
> > Subject: [PATCH] f2fs: keep dirty inodes selectively for checkpoint
> > 
> > This is to avoid no free segment bug during checkpoint caused by a number of
> > dirty inodes.
> > 
> > The case was reported by Chao like this.
> > 
> > 1. mount with lazytime option
> > 2. fragment space
> > 3. touch all files in the image
> > 4. umount
> > 
> > In this case, we actually don't need to flush dirty inode to inode page during
> > checkpoint.
> > 
> > Reported-by: Chao Yu <chao@...nel.org>
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> 
> Good job! IMO, main job of checkpoint is to keep filesystem being consistent,
> not flush dirty datas of vfs/fs as much as possible, if there are some
> restrictions for the interface like fsync, syncfs, sync, the caller of
> checkpoint() should do related job like marking lazytime inode I_DIRTY_SYNC or
> flush last data in dirty inode into filesystem's cache, and so on. :)
> 
> BTW, can you change commit log a bit as below:

Okay, not a big deal.

> 
> 1. mount with lazytime option
> 2. fill 4k file until disk is full
> 3. sync filesystem
> 4. read all files in the image
> 5. umount
> 
> Reviewed-by: Chao Yu <yuchao0@...wei.com>
> 
> Thanks,