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

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Date:   Fri, 17 Nov 2017 08:58:48 +0800
From:   Yunlong Song <yunlong.song@...wei.com>
To:     Chao Yu <yuchao0@...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

Is there any problem if just deleting the judgement condition in this patch?

On 2017/11/8 17:28, Chao Yu wrote:
> 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;
>>
>
> .
>

-- 
Thanks,
Yunlong Song