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From: bfields@fieldses.org (J. Bruce Fields)
To: Andreas Dilger <adilger@dilger.ca>
Cc: Eric Sandeen <sandeen@sandeen.net>,
	Qu Wenruo <quwenruo.btrfs@gmx.com>, Joshi <joshiiitr@gmail.com>,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: Re: cross-fs copy support
Date: Tue, 2 Oct 2018 14:28:00 -0400	[thread overview]
Message-ID: <20181002182800.GA8364@fieldses.org> (raw)
In-Reply-To: <FE6394EC-5CB0-4A16-AAC6-97F465A4E50C@dilger.ca>

On Mon, Oct 01, 2018 at 01:51:09PM -0600, Andreas Dilger wrote:
> \x1d
\b\x1d
\x1d
On Oct 1, 2018, at 9:49 AM, Eric Sandeen <sandeen@sandeen.net> wrote:
> > Yes, I would expect there to be problems with his modified kernel
> > for a filesystem that supports clone_file_range, because
> > vfs_copy_file_range() will clone if possible, and this should fail across
> > filesystems.
> > 
> > In general, though, I don't know for sure why we don't fall back to
> > do_splice_direct() across filesystems, although the filesystems that
> > implement their own ->copy_file_range ops may have their own,
> > further restrictions within their implementations.
> > 
> > This call /is/ documented in the manpage as only being valid for
> > files on the same filesystem, though:
> > http://man7.org/linux/man-pages/man2/copy_file_range.2.html
> 
> There was a patch to allow cross-mount copy for NFS, but it hasn't landed
> yet.

I thought Christoph Hellwig vetoed it partly because he thought NFS
server-to-server copy is too complicated.  Which perhaps it is, but I
suspect we'll do it anyway because the benefit seems obvious.

--b.

      parent reply	other threads:[~2018-10-03  1:12 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-01 14:32 Joshi
2018-10-01 14:48 ` Qu Wenruo
2018-10-01 15:15   ` Joshi
2018-10-01 15:49   ` Eric Sandeen
2018-10-01 19:51     ` Andreas Dilger
2018-10-02  8:15       ` David Sterba
2018-10-02 15:19         ` Darrick J. Wong
2018-10-02 18:28       ` J. Bruce Fields [this message]

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