linux-kernel - Re: [PATCH 2/2] xfs: fix stale data exposure problem when punch hole, collapse range or zero range across a delalloc extent

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Message-ID: <f4bf9490-0476-3a6a-55e0-786186669c6c@huawei.com>
Date:   Tue, 7 Jan 2020 10:09:44 +0800
From:   "yukuai (C)" <yukuai3@...wei.com>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
CC:     <bfoster@...hat.com>, <dchinner@...hat.com>, <sandeen@...deen.net>,
        <cmaiolino@...hat.com>, <hch@....de>, <linux-xfs@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <zhengbin13@...wei.com>,
        <yi.zhang@...wei.com>, <houtao1@...wei.com>
Subject: Re: [PATCH 2/2] xfs: fix stale data exposure problem when punch hole,
 collapse range or zero range across a delalloc extent



On 2020/1/7 5:57, Darrick J. Wong wrote:
> So your solution is to split the delalloc reservation to constrain the
> allocation to the range that's being operated on?
Yes, I'm trying to split delalloc reservation.
> 
> If so, I think a better solution (at least from the perspective of
> reducing fragmentation) would be to map the extent unwritten and force a
> post-writeback conversion[1] but I got shot down for performance reasons
> the last time I suggested that.
I'm wondering if spliting delalloc reservation have the same performance 
issue.

Thanks!
Yu Kuai