linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: avoid cpu lockup

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Date:   Mon, 17 Jul 2017 22:34:49 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: avoid cpu lockup

On 2017/7/16 9:04, Jaegeuk Kim wrote:
> Before retrying to flush data or dentry pages, we need to release cpu in order
> to prevent watchdog.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>

Reviewed-by: Chao Yu <yuchao0@...wei.com>

> ---
> Change log from v1:
>  - timeout more specifically
> 
>  fs/f2fs/checkpoint.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 56bbf592e487..5b876f6d3f6b 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -879,6 +879,7 @@ int sync_dirty_inodes(struct f2fs_sb_info *sbi, enum inode_type type)
>  	struct inode *inode;
>  	struct f2fs_inode_info *fi;
>  	bool is_dir = (type == DIR_INODE);
> +	unsigned long ino = 0;
>  
>  	trace_f2fs_sync_dirty_inodes_enter(sbi->sb, is_dir,
>  				get_pages(sbi, is_dir ?
> @@ -901,8 +902,17 @@ int sync_dirty_inodes(struct f2fs_sb_info *sbi, enum inode_type type)
>  	inode = igrab(&fi->vfs_inode);
>  	spin_unlock(&sbi->inode_lock[type]);
>  	if (inode) {
> +		unsigned long cur_ino = inode->i_ino;
> +
>  		filemap_fdatawrite(inode->i_mapping);
>  		iput(inode);
> +		/* We need to give cpu to another writers. */
> +		if (ino == cur_ino) {

We failed to flush dirty pages of inode due to encountering -EAGAIN of writepage?

Thanks,

> +			congestion_wait(BLK_RW_ASYNC, HZ/50);
> +			cond_resched();
> +		} else {
> +			ino = cur_ino;
> +		}
>  	} else {
>  		/*
>  		 * We should submit bio, since it exists several
>