From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: "yukuai (C)" <yukuai3@huawei.com>,
Gao Xiang <hsiangkao@redhat.com>,
darrick.wong@oracle.com, david@fromorbit.com,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, yi.zhang@huawei.com
Subject: Re: [RFC PATCH V3] iomap: add support to track dirty state of sub pages
Date: Fri, 21 Aug 2020 14:36:57 +0100 [thread overview]
Message-ID: <20200821133657.GU17456@casper.infradead.org> (raw)
In-Reply-To: <20200821061234.GE31091@infradead.org>
On Fri, Aug 21, 2020 at 07:12:34AM +0100, Christoph Hellwig wrote:
> iomap sets PagePrivate if a iomap_page structure is allocated. Right
> now that means for all pages on a file system with a block size smaller
> than the page size, although I hope we reduce that scope a little.
I was thinking about that. Is there a problem where we initially allocate
the page with a contiguous extent larger than the page, then later need
to write the page to a pair of extents?
If we're doing an unshare operation, then we know our src and dest iomaps
and can allocate the iop then. But if we readahead, we don't necessarily
know our eventual dest. So the conditions for skipping allocating an
iop are tricky to be sure we'll never need it.
next prev parent reply other threads:[~2020-08-21 13:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-19 12:05 [RFC PATCH V3] iomap: add support to track dirty state of sub pages Yu Kuai
2020-08-19 12:56 ` Gao Xiang
2020-08-20 1:38 ` yukuai (C)
2020-08-21 6:12 ` Christoph Hellwig
2020-08-21 13:36 ` Matthew Wilcox [this message]
2020-08-22 6:03 ` Christoph Hellwig
2020-08-22 14:24 ` Matthew Wilcox
2020-08-22 16:43 ` Christoph Hellwig
2020-08-21 6:17 ` Christoph Hellwig
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