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From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: xfs <linux-xfs@vger.kernel.org>,
	Brian Foster <bfoster@redhat.com>,
	Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] xfs: handle large CoW remapping requests
Date: Tue, 2 May 2017 00:50:21 -0700	[thread overview]
Message-ID: <20170502075021.GA7916@infradead.org> (raw)
In-Reply-To: <20170427212754.GB19158@birch.djwong.org>

On Thu, Apr 27, 2017 at 02:27:54PM -0700, Darrick J. Wong wrote:
> XFS transactions are constrained both by space and block reservation
> limits and the fact that we have to avoid doing 64-bit divisions.  This
> means that we can't remap more than 2^32 blocks at a time.  However,
> file logical blocks are 64-bit in size, so if we encounter a huge remap
> request we have to break it up into smaller pieces.

But where would we get that huge remap request from?  We already did the
BUILD_BUG_ON for the max read/write size at least.  Also the remaps
would now not be atomic, which would be a problem for my O_ATOMIC
implementation at least.

  reply	other threads:[~2017-05-02  7:50 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-27 21:27 [PATCH] xfs: handle large CoW remapping requests Darrick J. Wong
2017-05-02  7:50 ` Christoph Hellwig [this message]
2017-05-02 18:02   ` Darrick J. Wong
2017-05-04 11:54     ` Christoph Hellwig

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