linux-kernel - Re: [PATCH] f2fs: allow writeback on error status filesystem

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Date:   Mon, 8 Jun 2020 10:58:50 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>
Subject: Re: [PATCH] f2fs: allow writeback on error status filesystem

On 2020/6/8 5:17, Jaegeuk Kim wrote:
> On 06/05, Chao Yu wrote:
>>     71.07%     0.01%  kworker/u256:1+  [kernel.kallsyms]  [k] wb_writeback
>>             |
>>              --71.06%--wb_writeback
>>                        |
>>                        |--68.96%--__writeback_inodes_wb
>>                        |          |
>>                        |           --68.95%--writeback_sb_inodes
>>                        |                     |
>>                        |                     |--65.08%--__writeback_single_inode
>>                        |                     |          |
>>                        |                     |           --64.35%--do_writepages
>>                        |                     |                     |
>>                        |                     |                     |--59.83%--f2fs_write_node_pages
>>                        |                     |                     |          |
>>                        |                     |                     |           --59.74%--f2fs_sync_node_pages
>>                        |                     |                     |                     |
>>                        |                     |                     |                     |--27.91%--pagevec_lookup_range_tag
>>                        |                     |                     |                     |          |
>>                        |                     |                     |                     |           --27.90%--find_get_pages_range_tag
>>
>> If filesystem was injected w/ checkpoint errror, before umount, kworker
>> will always hold one core in order to writeback a large number of node
>> pages, that looks not reasonable, to avoid that, we can allow data/node
>> write in such case, since we can force all data/node writes with OPU mode,
>> and clear recovery flag on node, and checkpoint is not allowed as well,
>> so we don't need to worry about writeback's effect on data/node in
>> previous checkpoint, then with this way, it can decrease memory footprint
>> cost by node/data pages and avoid looping into data/node writeback
>> process.
> 
> This patch breaks fault injection test with filesystem corruption. Please check.

My bad, will check soon.

Thanks,

> 
>>
>> Signed-off-by: Chao Yu <yuchao0@...wei.com>
>> ---
>>  fs/f2fs/data.c | 19 ++++++++++++-------
>>  fs/f2fs/node.c |  7 +++++--
>>  2 files changed, 17 insertions(+), 9 deletions(-)
>>
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 9d40db50cd65..2b3c846181bb 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -2519,6 +2519,8 @@ bool f2fs_should_update_outplace(struct inode *inode, struct f2fs_io_info *fio)
>>  {
>>  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>>  
>> +	if (unlikely(f2fs_cp_error(sbi)))
>> +		return true;
>>  	if (f2fs_lfs_mode(sbi))
>>  		return true;
>>  	if (S_ISDIR(inode->i_mode))
>> @@ -2702,13 +2704,16 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
>>  	/* we should bypass data pages to proceed the kworkder jobs */
>>  	if (unlikely(f2fs_cp_error(sbi))) {
>>  		mapping_set_error(page->mapping, -EIO);
>> -		/*
>> -		 * don't drop any dirty dentry pages for keeping lastest
>> -		 * directory structure.
>> -		 */
>> -		if (S_ISDIR(inode->i_mode))
>> -			goto redirty_out;
>> -		goto out;
>> +
>> +		if (has_not_enough_free_secs(sbi, 0, 0)) {
>> +			/*
>> +			 * don't drop any dirty dentry pages for keeping lastest
>> +			 * directory structure.
>> +			 */
>> +			if (S_ISDIR(inode->i_mode))
>> +				goto redirty_out;
>> +			goto out;
>> +		}
>>  	}
>>  
>>  	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index 03e24df1c84f..372c04efad38 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -1527,7 +1527,10 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>>  			unlock_page(page);
>>  			return 0;
>>  		}
>> -		goto redirty_out;
>> +		if (has_not_enough_free_secs(sbi, 0, 0))
>> +			goto redirty_out;
>> +		set_fsync_mark(page, 0);
>> +		set_dentry_mark(page, 0);
>>  	}
>>  
>>  	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
>> @@ -1568,7 +1571,7 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>>  		goto redirty_out;
>>  	}
>>  
>> -	if (atomic && !test_opt(sbi, NOBARRIER))
>> +	if (atomic && !test_opt(sbi, NOBARRIER) && !f2fs_cp_error(sbi))
>>  		fio.op_flags |= REQ_PREFLUSH | REQ_FUA;
>>  
>>  	/* should add to global list before clearing PAGECACHE status */
>> -- 
>> 2.18.0.rc1
> .
>