linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: don't ignore writing pages on fsync during checkpoint=disable

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Message-ID: <bc9840f7-6fee-1ba4-ed82-b149f18934c9@kernel.org>
Date:   Thu, 26 Aug 2021 08:16:12 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: don't ignore writing pages on fsync
 during checkpoint=disable

On 2021/8/26 5:33, Jaegeuk Kim wrote:
> We must flush all the dirty data when enabling checkpoint back. Let's guarantee
> that first. In order to mitigate any failure, let's flush data in fsync as well
> during checkpoint=disable.

It needs to update comments a bit with respect to update part of v2?

> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
> v2 from v1:
>   - handle sync_inodes_sb() failure
> 
>   fs/f2fs/file.c  |  5 ++---
>   fs/f2fs/super.c | 11 ++++++++++-
>   2 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index cc2080866c54..3330efb41f22 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -263,8 +263,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>   	};
>   	unsigned int seq_id = 0;
>   
> -	if (unlikely(f2fs_readonly(inode->i_sb) ||
> -				is_sbi_flag_set(sbi, SBI_CP_DISABLED)))
> +	if (unlikely(f2fs_readonly(inode->i_sb)))
>   		return 0;
>   
>   	trace_f2fs_sync_file_enter(inode);
> @@ -278,7 +277,7 @@ static int f2fs_do_sync_file(struct file *file, loff_t start, loff_t end,
>   	ret = file_write_and_wait_range(file, start, end);
>   	clear_inode_flag(inode, FI_NEED_IPU);
>   
> -	if (ret) {
> +	if (ret || is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
>   		trace_f2fs_sync_file_exit(inode, cp_reason, datasync, ret);
>   		return ret;
>   	}
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 49e153fd8183..d2f97dfb17af 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2088,8 +2088,17 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
>   
>   static void f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
>   {
> +	int retry = DEFAULT_RETRY_IO_COUNT;
> +
>   	/* we should flush all the data to keep data consistency */
> -	sync_inodes_sb(sbi->sb);
> +	do {
> +		sync_inodes_sb(sbi->sb);
> +		cond_resched();
> +		congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
> +	} while (get_pages(sbi, F2FS_DIRTY_DATA) && retry--);
> +
> +	if (unlikely(!retry))

Well, if we break the loop due to retry-- == 0, value of retry will be -1 here.

So should be:

if (unlikely(retry < 0))

Thanks,

> +		f2fs_warn(sbi, "checkpoint=enable has some unwritten data.");
>   
>   	down_write(&sbi->gc_lock);
>   	f2fs_dirty_to_prefree(sbi);
>