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Date: Tue, 16 Sep 2014 09:50:32 +0800
From: Gu Zheng <guz.fnst@cn.fujitsu.com>
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To: Chao Yu <chao2.yu@samsung.com>
CC: Jaegeuk Kim <jaegeuk@kernel.org>, Changman Lee <cm224.lee@samsung.com>,
        <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [f2fs-dev][PATCH 4/5] f2fs: fix to clean previous mount option
 when remount_fs
References: <003001cfd0cc$96f9e8e0$c4edbaa0$@samsung.com>
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Hi Yu,
On 09/15/2014 06:04 PM, Chao Yu wrote:

> In manual of mount, we descript remount as below:
> 
> "mount -o remount,rw /dev/foo /dir
> After  this call all old mount options are replaced and arbitrary stuff from
> fstab is ignored, except the loop= option which is internally generated and
> maintained by the mount command."
> 
> Previously f2fs do not clear up old mount options when remount_fs, so we have no
> chance of disabling previous option (e.g. flush_merge). Fix it.

Please don't.
"Remount" should just change what you specified and keep others unchanged.
The problem here is that we need to provide mount opts for disable/enable
some features, but we missed it. So the right way is adding these opts if
we really need them.

Thanks,
Gu

> 
> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> ---
>  fs/f2fs/super.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 54444bb..90fcbe0 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -616,6 +616,9 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
>  	org_mount_opt = sbi->mount_opt;
>  	active_logs = sbi->active_logs;
>  
> +	sbi->mount_opt.opt = 0;
> +	sbi->active_logs = NR_CURSEG_TYPE;
> +
>  	/* parse mount options */
>  	err = parse_options(sb, data);
>  	if (err)