From: Alyssa Ross <hi@alyssa.is>
To: devel@spectrum-os.org
Subject: [PATCH 14/22] host/initramfs/extfs.nix: tar2ext4 -> mkfs.ext4 -d
Date: Mon, 10 Oct 2022 23:28:54 +0000 [thread overview]
Message-ID: <20221010232909.1953738-15-hi@alyssa.is> (raw)
In-Reply-To: <20221010232909.1953738-1-hi@alyssa.is>
tar2ext4 is designed for making read-only, minimally-sized ext4
images. That's great for the Spectrum host system's root filesystem,
but it doesn't make sense for the user data partition, because even if
we mark it read/write after running tar2ext4, there will be very few
inodes available, so it won't be very useful for storing data.
To fix this, we use the normal tools for creating an ext4 filesystem.
We create a sparse image of an extremely large size to ensure there's
enough space available for metadata and things for the partition to
grow to fit any disk a user might want to to use Spectrum on, then
shrink the image down to its minimum size.
Doing it this way assumes that the build environment will always
support sparse files. If this turns out not to be the case, we can
use mkfs.ext4's -E resize= option to set the maximum expected disk
size, and use a smaller size for the initial image size. I haven't
done that here to avoid having to pick that smaller number.
Now that the filesystem is no longer marked as read-only, we need to
fsck it before every mount, or it won't mount any more after the first
time.
Signed-off-by: Alyssa Ross <hi@alyssa.is>
---
host/initramfs/extfs.nix | 16 +++++++++++-----
host/rootfs/etc/s6-rc/ext/up | 1 +
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/host/initramfs/extfs.nix b/host/initramfs/extfs.nix
index 0ee337b..a510c02 100644
--- a/host/initramfs/extfs.nix
+++ b/host/initramfs/extfs.nix
@@ -1,7 +1,7 @@
# SPDX-FileCopyrightText: 2021-2022 Alyssa Ross <hi@alyssa.is>
# SPDX-License-Identifier: MIT
-{ config, runCommand, tar2ext4 }:
+{ config, runCommand, e2fsprogs, tar2ext4 }:
let
netvm = import ../../vm/sys/net {
@@ -15,9 +15,10 @@ let
in
runCommand "ext.ext4" {
- nativeBuildInputs = [ tar2ext4 ];
+ nativeBuildInputs = [ e2fsprogs ];
} ''
- mkdir -p svc/data/appvm-{catgirl,lynx,mg}
+ mkdir -p root/svc/data/appvm-{catgirl,lynx,mg,nix}
+ cd root
tar -C ${netvm} -c data | tar -C svc -x
chmod +w svc/data
@@ -26,6 +27,11 @@ runCommand "ext.ext4" {
tar -C ${appvm-lynx} -c . | tar -C svc/data/appvm-lynx -x
tar -C ${appvm-mg} -c . | tar -C svc/data/appvm-mg -x
- tar -cf ext.tar svc
- tar2ext4 -i ext.tar -o $out
+ mkfs.ext4 -d . $out 16T
+ resize2fs -M $out
+
+ # The generated image will have all files owned by the uid and gid
+ # mkfs.ext4 was run as, so we need to normalize ownership to root.
+ find -exec echo $'set_inode_field {} uid 0\nset_inode_field {} gid 0' ';' |
+ debugfs -wf - $out
''
diff --git a/host/rootfs/etc/s6-rc/ext/up b/host/rootfs/etc/s6-rc/ext/up
index c189471..78b2637 100644
--- a/host/rootfs/etc/s6-rc/ext/up
+++ b/host/rootfs/etc/s6-rc/ext/up
@@ -2,5 +2,6 @@
# SPDX-FileCopyrightText: 2021-2022 Alyssa Ross <hi@alyssa.is>
if { /etc/mdev/wait ext }
+foreground { fsck.ext4 -fp /dev/ext }
if { resize2fs /dev/ext }
mount /dev/ext /ext
--
2.37.1
next prev parent reply other threads:[~2022-10-10 23:32 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-10 23:28 [PATCH 00/22] Implement managing VMs with Nix Alyssa Ross
2022-10-10 23:28 ` [PATCH 01/22] host/start-vm: use MAP_SHARED memory for VMs Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 02/22] host/start-vm: implement shared directories Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 03/22] host/rootfs: generate virtiofsd services Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 04/22] Documentation: explain VM shared directories Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 05/22] vm-lib/make-vm.nix: support " Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 06/22] img/app: add support for testing virtiofs Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 07/22] img/app: don't block app startup on network online Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 08/22] img/app: auto-mount virtiofs0 filesystem Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 09/22] vm/app/mg.nix: init Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 10/22] vm/app/mg.nix: open virtio filesystem in dired Alyssa Ross
2023-02-26 19:17 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 11/22] host/rootfs: move ext mounting to s6-rc service Alyssa Ross
2022-11-14 1:14 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 12/22] host/rootfs: automatically grow user partition Alyssa Ross
2022-11-14 1:14 ` Alyssa Ross
2022-10-10 23:28 ` [PATCH 13/22] host/rootfs: use a bigger test ext partition Alyssa Ross
2022-11-14 1:14 ` Alyssa Ross
2022-10-10 23:28 ` Alyssa Ross [this message]
2022-11-14 1:14 ` [PATCH 14/22] host/initramfs/extfs.nix: tar2ext4 -> mkfs.ext4 -d Alyssa Ross
2022-10-10 23:28 ` [PATCH 15/22] host/start-vm: resolve VM symlinks with /ext root Alyssa Ross
2022-10-10 23:28 ` [PATCH 16/22] host/rootfs: " Alyssa Ross
2022-10-10 23:28 ` [PATCH 17/22] Documentation: explain /ext symlink resolution Alyssa Ross
2022-10-10 23:28 ` [PATCH 18/22] host/start-vm: increase memory size to 512M Alyssa Ross
2022-10-10 23:28 ` [PATCH 19/22] vm/app/nix: add Alyssa Ross
2022-10-10 23:29 ` [PATCH 20/22] vm-lib/make-vms.nix: add Alyssa Ross
2022-10-10 23:29 ` [PATCH 21/22] host/initramfs/extfs.nix: add example Nix-built VM Alyssa Ross
2022-10-10 23:29 ` [PATCH 22/22] Documentation: add how-to guide for Nix-built VMs Alyssa Ross
2022-10-10 23:29 ` [PATCH v2 0/6] Introduce a shared base for application VMs Alyssa Ross
2022-10-10 23:37 ` Alyssa Ross
2022-10-10 23:29 ` [PATCH v2 1/6] host/start-vm: support multiple block devices Alyssa Ross
2022-10-10 23:29 ` [PATCH v2 2/6] scripts/make-gpt.sh: add support for labels Alyssa Ross
2022-10-10 23:29 ` [PATCH v2 3/6] vm: build GPT images Alyssa Ross
2022-10-10 23:29 ` [PATCH v2 4/6] host/start-vm: boot using partition label Alyssa Ross
2022-10-10 23:29 ` [PATCH v2 5/6] release: rename from "img" Alyssa Ross
2022-10-10 23:29 ` [PATCH v2 6/6] img/app: extract from appvm-{lynx,catgirl} Alyssa Ross
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