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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 09:57:03 +0800	[thread overview]
Message-ID: <857fa4e7-c529-40cf-9916-151d91e815c4@huawei.com> (raw)
In-Reply-To: <20200119014213.GA16943@bombadil.infradead.org>



On 2020/1/19 9:42, Matthew Wilcox wrote:
> Did you read my patch series?  The current code allocates pages,
> but does not put them in the page cache until after iomap is called.
> My patch series changes that to put the pages in the page cache as soon
> as they're allocated, and before iomap is called.

The current code to determin if page need to be allocated:

     page = xa_load(&mapping->i_pages, page_offset);
     if (page && !xa_is_value(page)) {
       /*
       ┊* Page already present?  Kick off the current batch of
       ┊* contiguous pages before continuing with the next
       ┊* batch.
       ┊*/
       if (nr_pages)
         read_pages(mapping, filp, &page_pool, nr_pages,
             gfp_mask);
       nr_pages = 0;
       continue;
     }

     page = __page_cache_alloc(gfp_mask);
     if (!page)
       break;

Page will be allocated if the page do not exist in page cache. And I
don't see your patch series change that. Or am I missing something?

Thanks!
Yu Kuai


  reply	other threads:[~2020-01-19  1:57 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)
2020-01-19  1:42     ` Matthew Wilcox
2020-01-19  1:57       ` yukuai (C) [this message]
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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