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From: "yukuai (C)" <yukuai3@huawei.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: <hch@infradead.org>, <darrick.wong@oracle.com>,
	<linux-xfs@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <houtao1@huawei.com>,
	<zhengbin13@huawei.com>, <yi.zhang@huawei.com>
Subject: Re: [RFC] iomap: fix race between readahead and direct write
Date: Sun, 19 Jan 2020 09:34:32 +0800	[thread overview]
Message-ID: <f5328338-1a2d-38b4-283f-3fb97ad37133@huawei.com> (raw)
In-Reply-To: <20200118230826.GA5583@bombadil.infradead.org>



On 2020/1/19 7:08, Matthew Wilcox wrote:
> It's worth noting that my patch series from earlier this week to
> redesign the readahead API will fix this problem.  Direct write will block
> on the locked pages in the page cache.

Thank you for your response!

In this case, direct write finish while page do not exist in the page
cache. This is the fundamental condition of the race, because readahead
won't allocate page if page exist in page cache.

By the way, in the current logic, if page exist in page cache, direct
write need to hold lock for page in invalidate_inode_pages2_range().

Thanks!
Yu Kuai





  reply	other threads:[~2020-01-19  1:34 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16  6:36 [RFC] iomap: fix race between readahead and direct write yu kuai
2020-01-16 15:32 ` Jan Kara
2020-01-17  9:39   ` yukuai (C)
2020-01-17 11:05     ` Jan Kara
2020-01-17 16:24       ` Darrick J. Wong
2020-01-19  1:25         ` yukuai (C)
2020-01-19  1:17       ` yukuai (C)
2020-01-20 11:42         ` Jan Kara
2020-01-18 23:08 ` Matthew Wilcox
2020-01-19  1:34   ` yukuai (C) [this message]
2020-01-19  1:42     ` Matthew Wilcox
2020-01-19  1:57       ` yukuai (C)
2020-01-19  2:51       ` yukuai (C)
2020-01-19  3:01         ` Gao Xiang
2020-01-19  3:15           ` yukuai (C)
2020-01-19  6:14         ` Matthew Wilcox
2020-01-19  6:55           ` yukuai (C)
2020-01-19  7:58             ` Matthew Wilcox
2020-01-19 11:21               ` yukuai (C)

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