From: Gao Xiang <gaoxiang25@huawei.com>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>, <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 11:01:25 +0800 [thread overview]
Message-ID: <20200119030123.GA223124@architecture4> (raw)
In-Reply-To: <64d617cc-e7fe-6848-03bb-aab3498c9a07@huawei.com>
On Sun, Jan 19, 2020 at 10:51:37AM +0800, yukuai (C) wrote:
>
>
> Then, there might be a problem in your implementation.
> if 'use_list' is set to true here:
> + bool use_list = mapping->a_ops->readpages;
>
> Your code do not call add_to_page_cache_lru for the page.
IMO, if use_list == true, it will call read_pages -> .readpages
and go just like the current implementation.
->.readahead is just alloc_page and then add_to_page_cache_lru
right after in time and in principle it saves some extra page
allocation.
Thanks,
Gao Xiang
> + if (use_list) {
> + page->index = page_offset;
> + list_add(&page->lru, &page_pool);
> + } else if (!add_to_page_cache_lru(page, mapping, page_offset,
> + gfp_mask)) {
> + if (nr_pages)
> + read_pages(mapping, filp, &page_pool,
> + page_offset - nr_pages,
> + nr_pages);
> + nr_pages = 0;
> + continue;
> + }
>
next prev parent reply other threads:[~2020-01-19 3:02 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)
2020-01-19 2:51 ` yukuai (C)
2020-01-19 3:01 ` Gao Xiang [this message]
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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