Bug#1021908: marked as done (dpkg: support f2fs filesystem compression)

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Your message dated Tue, 9 Jun 2026 04:07:26 +0200
with message-id <[email protected]>
and subject line Re: Bug#1021908: dpkg: support f2fs filesystem compression
has caused the Debian Bug report #1021908,
regarding dpkg: support f2fs filesystem compression
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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1021908: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=3D1021908
Debian Bug Tracking System
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From: Shawn Landden <[email protected]>
To: Debian Bug Tracking System <[email protected]>
Subject: dpkg: support l2fs filesystem compression
Message-ID: <166599233998.4158.7704615673649971401.reportbug@shawn-candy>
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Date: Mon, 17 Oct 2022 00:38:59 -0700
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Package: dpkg
Version: 1.20.11
Severity: wishlist
X-Debbugs-Cc: [email protected]

I found that zfs's compression (available with Ubuntu's install) was not satisfactory on small eMMCs
because it requires a seperate /boot partition and does not support swap files.

The F2FS filesystem supports compression, with a special caveat that in order to actually make
the files consume less space (they always use less space, which effects performance and health),
they must be marked as immutable, and before being changed they must be marked as mutable again,
consuming the uncompressed size in terms of filesystem accounting.

dpkg has a good idea of what files are read-only, and could be configured to mark files as immutable,
except conffiles, which would make installation on of Debian tiny Chromebook eMMCs a much better
experience than with ext4.

Thanks,

Shawn Paul Landden


-- Package-specific info:
System tainted due to merged-usr-via-aliased-dirs.

-- System Information:
Debian Release: 11.4
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.10.0-16-amd64 (SMP w/2 CPU threads)
Kernel taint flags: TAINT_WARN
Locale: LANG=es_US.UTF-8, LC_CTYPE=es_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages dpkg depends on:
ii  libbz2-1.0   1.0.8-4
ii  libc6        2.31-13+deb11u3
ii  liblzma5     5.2.5-2.1~deb11u1
ii  libselinux1  3.1-3
ii  tar          1.34+dfsg-1
ii  zlib1g       1:1.2.11.dfsg-2+deb11u1

dpkg recommends no packages.

Versions of packages dpkg suggests:
ii  apt            2.2.4
pn  debsig-verify  <none>

-- no debconf information

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Date: Tue, 9 Jun 2026 04:07:26 +0200
From: Guillem Jover <[email protected]>
To: Shawn Landden <[email protected]>, [email protected]
Subject: Re: Bug#1021908: dpkg: support f2fs filesystem compression
Message-ID: <[email protected]>
References: <166599233998.4158.7704615673649971401.reportbug@shawn-candy>
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In-Reply-To: <166599233998.4158.7704615673649971401.reportbug@shawn-candy>

Hi!

On Mon, 2022-10-17 at 00:38:59 -0700, Shawn Landden wrote:
> Package: dpkg
> Version: 1.20.11
> Severity: wishlist
> X-Debbugs-Cc: [email protected]

> I found that zfs's compression (available with Ubuntu's install) was
> not satisfactory on small eMMCs because it requires a seperate /boot
> partition and does not support swap files.
> 
> The F2FS filesystem supports compression, with a special caveat that
> in order to actually make the files consume less space (they always
> use less space, which effects performance and health), they must be
> marked as immutable, and before being changed they must be marked as
> mutable again, consuming the uncompressed size in terms of filesystem
> accounting.
> 
> dpkg has a good idea of what files are read-only, and could be
> configured to mark files as immutable, except conffiles, which would
> make installation on of Debian tiny Chromebook eMMCs a much better
> experience than with ext4.

What I found about f2fs compression in the kernel documentation at
https://docs.kernel.org/filesystems/f2fs.html#compression-implementation
is that it requires either chattr +c or mount options to enable it.

For dpkg to use this, it would need to have explicit support for a
Linux filesystem specific ioctl, scan all mounted filesystems and know
when it can apply it during unpack, and then grow options to select
whether to enable this. In addition I guess it would also ideally not
mark for compression files that are already compressed, which means
it might need to either detect that during unpack of the multiple
possible compression types, or have a list of extensions.

I think the user of the filesystem is in a better position to specify
this probably in the mount options. So I'm going to be closing this
one.

Sorry,
Guillem
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