linux-kernel - Re: [PATCH v2 1/2] f2fs: dax: fix races between page faults and truncating pages

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Message-ID: <29f704b5-b187-9c26-c60e-8459fa03a710@huawei.com>
Date:   Wed, 7 Jun 2017 17:41:07 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     sunqiuyang <sunqiuyang@...wei.com>, <linux-kernel@...r.kernel.org>,
        <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [PATCH v2 1/2] f2fs: dax: fix races between page faults and
 truncating pages

On 2017/5/18 11:06, sunqiuyang wrote:
> From: Qiuyang Sun <sunqiuyang@...wei.com>
> 
> Currently in F2FS, page faults and operations that truncate the pagecahe
> or data blocks, are completely unsynchronized. This can result in page
> fault faulting in a page into a range that we are changing after
> truncating, and thus we can end up with a page mapped to disk blocks that
> will be shortly freed. Filesystem corruption will shortly follow.
> 
> This patch fixes the problem by creating new rw semaphore i_mmap_sem in
> f2fs_inode_info and grab it for functions removing blocks from extent tree
> and for read over page faults. The mechanism is similar to that in ext4.
> 
> Signed-off-by: Qiuyang Sun <sunqiuyang@...wei.com>

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