linux-kernel - Re: [PATCH] f2fs: collect prefree segments to avoild write checkpoint fail

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Message-ID: <b0e3c139-1458-ff89-9ac8-8cba0ebef421@huawei.com>
Date:   Mon, 28 Aug 2017 17:52:46 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Yunlong Song <yunlong.song@...wei.com>, <jaegeuk@...nel.org>,
        <chao@...nel.org>, <yunlong.song@...oud.com>
CC:     <miaoxie@...wei.com>, <bintian.wang@...wei.com>,
        <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] f2fs: collect prefree segments to avoild write checkpoint
 fail

Hi Yunlong,

On 2017/8/26 19:46, Yunlong Song wrote:
> In come corner case, the reserved segments are used to do gc, and there are
> not enough free segments for write checkpoint to finish its job, then the
> gc process will fail to change the prefree segments to free segments.

How about doing investigate that why we haven't enough free segment for GC?

Thanks,

> 
> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
> ---
>  fs/f2fs/gc.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index cd147e7..c8a828f 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1056,6 +1056,13 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
>  	if (!sync) {
>  		if (has_not_enough_free_secs(sbi, sec_freed, 0)) {
>  			segno = NULL_SEGNO;
> +			if (prefree_segments(sbi) &&
> +				has_not_enough_free_secs(sbi,
> +					reserved_sections(sbi), 0)) {
> +				ret = write_checkpoint(sbi, &cpc);
> +				if (ret)
> +					goto stop;
> +			}
>  			goto gc_more;
>  		}
>  
>