From: Christoph Hellwig <hch@infradead.org>
To: Cerem Cem ASLAN <ceremcem@ceremcem.net>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: Will Btrfs have an official command to "uncow" existing files?
Date: Sun, 22 Jan 2023 23:17:49 -0800 [thread overview]
Message-ID: <Y840neK7y/u8Dpn2@infradead.org> (raw)
In-Reply-To: <CAN4oSBcsfBPWUc9pwhSrRu5omkP7m8ZUqhFbF-w_DwQJ3Q_aSQ@mail.gmail.com>
On Sun, Jan 22, 2023 at 02:41:22PM +0300, Cerem Cem ASLAN wrote:
> Original post is here: https://www.spinics.net/lists/linux-btrfs/msg58055.html
>
> The problem with the "chattr +C ..., move back and forth" approach is
> that the VM folder is about 300GB and I have ~100GB of free space,
> plus, I have multiple copies which will require that 300GB to
> re-transfer after deleting all previous snapshots (because there is no
> enough free space on those backup hard disks).
>
> So, we really need to set the NoCow attribute for the existing files.
>
> Should we currently use a separate partition for VMs and mount it with
> nodatacow option to avoid that issue?
So, Linux for a while now has the FALLOC_FL_UNSHARE_RANGE flag to
fallocate to unshare previously shared extents. It still lacks an
implementation for btrfs, but it seems to be the interface that you
want.
next prev parent reply other threads:[~2023-01-23 7:17 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-22 11:41 Will Btrfs have an official command to "uncow" existing files? Cerem Cem ASLAN
2023-01-22 16:55 ` Forza
2023-01-22 20:27 ` Goffredo Baroncelli
2023-01-23 0:20 ` Zygo Blaxell
2023-01-30 16:39 ` Patrik Lundquist
2023-01-31 11:25 ` Patrik Lundquist
2023-01-23 7:17 ` Christoph Hellwig [this message]
2023-01-29 0:40 ` Zygo Blaxell
-- strict thread matches above, loose matches on Subject: below --
2016-08-21 18:59 Tomokhov Alexander
2016-08-22 2:00 ` Duncan
2016-08-22 23:54 ` Tomokhov Alexander
2016-08-22 20:14 ` Jeff Mahoney
2016-08-22 22:53 ` Tomokhov Alexander
2016-08-22 23:06 ` Darrick J. Wong
2016-08-23 2:43 ` Chris Murphy
2016-08-23 11:23 ` Austin S. Hemmelgarn
2016-08-24 18:34 ` Omar Sandoval
2016-08-24 22:42 ` Darrick J. Wong
2016-08-24 22:47 ` Omar Sandoval
2016-08-23 5:54 ` Dave Chinner
2016-08-24 0:48 ` Jeff Mahoney
2016-08-24 1:03 ` Darrick J. Wong
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