bcachefs: enable in-tree module and add userspace-tools sysext

build_library/extra_sysexts.sh

@@ -1,4 +1,5 @@
 EXTRA_SYSEXTS=(
+  "bcachefs|sys-fs/bcachefs-tools|-modules|amd64"
   "overlaybd|sys-fs/overlaybd,app-containers/accelerated-container-image"
   "incus|app-containers/incus"
   "nvidia-drivers-535|x11-drivers/nvidia-drivers:0/535|-kernel-open persistenced|amd64"

build_library/sysext_mangle_flatcar-bcachefs

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+set -euo pipefail
+rootfs="${1}"
+
+pushd "${rootfs}"
+
+# Drop dev/debug/initramfs files — the sysext only needs runtime bits.
+rm -rf ./usr/{lib/debug/,lib64/cmake/,include/}
+rm -rf ./usr/lib/dracut/
+rm -rf ./usr/share/initramfs-tools
+rm -rf ./usr/src
+rm -rf ./usr/share/man
+rm -rf ./usr/share/doc
+rm -rf ./usr/lib/pkgconfig
+rm -rf ./usr/lib64/pkgconfig
+
+# /usr/sbin on Flatcar is a symlink to /usr/bin; shipping a /usr/sbin
+# directory in a sysext would clobber the symlink at merge time. Relocate
+# anything the tools ebuild installed there. `cp -a src/. dst/` includes
+# dotfiles (Portage `.keep*` placeholders) so nothing lingers to make the
+# subsequent `rm -rf` racy.
+if [ -d ./usr/sbin ]; then
+  mkdir -p ./usr/bin
+  cp -a ./usr/sbin/. ./usr/bin/
+  rm -rf ./usr/sbin
+fi
+
+popd

changelog/changes/2026-07-08-bcachefs.md

@@ -0,0 +1 @@
+- Enabled the in-tree bcachefs kernel module (`CONFIG_BCACHEFS_FS=m` with POSIX ACLs) and provided a companion bcachefs Flatcar extension as an optional systemd-sysext image with the release. Write `bcachefs` to `/etc/flatcar/enabled-sysext.conf` through Ignition and the sysext will be installed during provisioning; it ships the userspace utilities (`mkfs.bcachefs`, `mount.bcachefs`, ...) that pair with the kernel module. bcachefs is still experimental (pre-1.0 on-disk format) and is not supported for the root partition.

sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.12

@@ -24,6 +24,8 @@ CONFIG_AUTOFS_FS=y
 CONFIG_B44=m
 # CONFIG_BACKLIGHT_CLASS_DEVICE is not set
 CONFIG_BCACHE=m
+CONFIG_BCACHEFS_FS=m
+CONFIG_BCACHEFS_POSIX_ACL=y
 CONFIG_BCM87XX_PHY=m
 CONFIG_BFQ_GROUP_IOSCHED=y
 CONFIG_BINFMT_MISC=m