linux-kernel - Re: [PATCH] f2fs: let f2fs also gc atomic file to avoid loop gc

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Date:   Wed, 8 Nov 2017 17:28:30 +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: let f2fs also gc atomic file to avoid loop gc

On 2017/11/8 10:34, Yunlong Song wrote:
> If some files are opened with atomic flag and have not commited yet, at
> the same time, if all the target victim segments have at least one page
> of these atomic files, then f2fs gc will fail to do gc and hangs in the
> process of go to gc_more, since gc_date_segment will not move any data
> and get_valid_blocks will never be 0, then do_garbage_collect will
> always return 0.

Oh, I added this judgment condition to avoid ruining atomic write by data
GC, could we find another way to solve this issue? BTW, if there is direct
IO, we will also skip data segment GC.

Thanks,

> 
> Signed-off-by: Yunlong Song <yunlong.song@...wei.com>
> ---
>  fs/f2fs/gc.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 5d5bba4..3fdcd04 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -621,9 +621,6 @@ static void move_data_block(struct inode *inode, block_t bidx,
>  	if (!check_valid_map(F2FS_I_SB(inode), segno, off))
>  		goto out;
>  
> -	if (f2fs_is_atomic_file(inode))
> -		goto out;
> -
>  	set_new_dnode(&dn, inode, NULL, NULL, 0);
>  	err = get_dnode_of_data(&dn, bidx, LOOKUP_NODE);
>  	if (err)
> @@ -718,9 +715,6 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
>  	if (!check_valid_map(F2FS_I_SB(inode), segno, off))
>  		goto out;
>  
> -	if (f2fs_is_atomic_file(inode))
> -		goto out;
> -
>  	if (gc_type == BG_GC) {
>  		if (PageWriteback(page))
>  			goto out;
>