linux-kernel - Re: [PATCH] nilfs2: fix data loss with mmap()

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Message-Id: <20140919.084107.1306407610758412217.konishi.ryusuke@lab.ntt.co.jp>
Date:	Fri, 19 Sep 2014 08:41:07 +0900 (JST)
From:	Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-nilfs@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Andreas Rohner <andreas.rohner@....net>
Subject: Re: [PATCH] nilfs2: fix data loss with mmap()

On Thu, 18 Sep 2014 12:17:08 -0700, Andrew Morton wrote:
> On Thu, 18 Sep 2014 23:56:25 +0900 Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp> wrote:
> 
>> From: Andreas Rohner <andreas.rohner@....net>
>> 
>> This bug leads to reproducible silent data loss, despite the use of
>> msync(), sync() and a clean unmount of the file system. It is easily
>> reproducible with the following script:
>> 
>> ...
>>
>> --- a/fs/nilfs2/inode.c
>> +++ b/fs/nilfs2/inode.c
>> @@ -219,10 +219,10 @@ static int nilfs_writepage(struct page *page, struct writeback_control *wbc)
>>  
>>  static int nilfs_set_page_dirty(struct page *page)
>>  {
>> +	struct inode *inode = page->mapping->host;
>>  	int ret = __set_page_dirty_nobuffers(page);
>>  
>>  	if (page_has_buffers(page)) {
>> -		struct inode *inode = page->mapping->host;
>>  		unsigned nr_dirty = 0;
>>  		struct buffer_head *bh, *head;
>>  
>> @@ -245,6 +245,10 @@ static int nilfs_set_page_dirty(struct page *page)
>>  
>>  		if (nr_dirty)
>>  			nilfs_set_file_dirty(inode, nr_dirty);
>> +	} else if (ret) {
>> +		unsigned nr_dirty = 1 << (PAGE_SHIFT - inode->i_blkbits);
> 
> It's quite cosmetic, but it is conventional to use PAGE_CACHE_SHIFT here.

Agreed.

Thanks,
Ryusuke Konishi
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