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Date:   Sun, 7 Jun 2020 14:17:48 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, chao@kernel.org
Subject: Re: [PATCH] f2fs: allow writeback on error status filesystem
Message-ID: <20200607211748.GA26785@google.com>
References: <20200605085453.45717-1-yuchao0@huawei.com>
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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.

> 
> Signed-off-by: Chao Yu <yuchao0@huawei.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