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From:   OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To:     Hou Tao <houtao1@huawei.com>
Cc:     <linux-fsdevel@vger.kernel.org>, <viro@zeniv.linux.org.uk>,
        <jack@suse.cz>, <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] fat: issue flush after the writeback of FAT
References: <20190409030158.136316-1-houtao1@huawei.com>
Date:   Tue, 09 Apr 2019 14:16:44 +0900
In-Reply-To: <20190409030158.136316-1-houtao1@huawei.com> (Hou Tao's message
        of "Tue, 9 Apr 2019 11:01:58 +0800")
Message-ID: <87ef6bbvwj.fsf@mail.parknet.co.jp>
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Hou Tao <houtao1@huawei.com> writes:

> fsync() needs to make sure the data & meta-data of file are persistent
> after the return of fsync(), even when a power-failure occurs later.
> In the case of fat-fs, the FAT belongs to the meta-data of file,
> so we need to issue a flush after the writeback of FAT instead before.
>
> Also bail out early when any stage of fsync fails.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>

Looks good.

Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

> ---
>  fs/fat/file.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/fs/fat/file.c b/fs/fat/file.c
> index b3bed32946b1..0e3ed79fcc3f 100644
> --- a/fs/fat/file.c
> +++ b/fs/fat/file.c
> @@ -193,12 +193,17 @@ static int fat_file_release(struct inode *inode, struct file *filp)
>  int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
>  {
>  	struct inode *inode = filp->f_mapping->host;
> -	int res, err;
> +	int err;
> +
> +	err = __generic_file_fsync(filp, start, end, datasync);
> +	if (err)
> +		return err;
>  
> -	res = generic_file_fsync(filp, start, end, datasync);
>  	err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
> +	if (err)
> +		return err;
>  
> -	return res ? res : err;
> +	return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
>  }

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>