linux-kernel - Re: [PATCH] f2fs: fix wrong bfree and bavail

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Date:   Wed, 6 Sep 2017 11:07:57 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
CC:     <stable@...r.kernel.org>
Subject: Re: [PATCH] f2fs: fix wrong bfree and bavail

On 2017/9/6 5:06, Jaegeuk Kim wrote:
> This patch fixes bavail and bfree finally.
> 
> long    f_bfree;    /* free blocks in fs */
> long    f_bavail;   /* free blocks avail to non-superuser */
> 
> So, bfree represents all the reserved blocks, while bavail does the space only
> visible to normal user.
> 
> Fix: 3e6d0b4d9c1c ("f2fs: fix incorrect f_bfree calculation in ->statfs")
> Cc: <stable@...r.kernel.org> # 4.8+
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>  fs/f2fs/super.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 7e29db227910..17cca4cb93af 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -955,8 +955,8 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
>  	buf->f_bsize = sbi->blocksize;
>  
>  	buf->f_blocks = total_count - start_count;
> -	buf->f_bfree = user_block_count - valid_user_blocks(sbi) + ovp_count;
> -	buf->f_bavail = user_block_count - valid_user_blocks(sbi) -
> +	buf->f_bfree = user_block_count - valid_user_blocks(sbi);
> +	buf->f_bavail = user_block_count - valid_user_blocks(sbi) - ovp_count -

	set_cp(user_block_count, ((get_cp(free_segment_count) + 6 -
			get_cp(overprov_segment_count)) * c.blks_per_seg));

As we calculated in mkfs, we have removed ovp_count in user_block_count, so
shouldn't we add ovp_count for f_bfree here?

Thanks,

>  						sbi->reserved_blocks;
>  
>  	avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
>