Btrfs migration 1: subvolume foundation#95
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alchark
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Define the subvolume layout (@, @home, @var-log, @var-cache, @snapshots, boot) with per-subvolume mount options, keep /boot uncompressed so U-Boot can read the kernel/dtb/initrd, and factor out root device retrieval into a helper. Generate the BLS boot entries, deriving the devicetreedir/overlay prefix from each entry's root subvolume so U-Boot resolves the in-entry paths correctly, with FDT_SUBVOL_PREFIX as an override. Install btrfs-progs and btrfs-compsize.
journald's append-heavy writes fragment badly under btrfs copy-on-write. Pre-create the journal directory with NODATACOW while it is still empty so the journal files written on first boot inherit it.
Once the rootfs and kernel are fully deployed, take a read-only snapshot of @ into .snapshots/@_Factory-Image for rollback. It captures @ only; the nested subvolumes (boot/home/var-*) are separate and excluded.
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alchark
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First part of the btrfs migration. Establishes the btrfs root and a single-root subvolume layout.
@,@home,@var-log,@var-cache,@snapshots,boot) with per-subvolume mount options;/bootkept uncompressed so U-Boot can read the kernel/dtb/initrd regardless of its btrfs zstd support.NODATACOWon the systemd journal directory to avoid btrfs CoW fragmentation./.snapshotsleft unmounted at runtime for safety.@taken once rootfs and kernel are deployed.devicetreedirpath resolution fixed so U-Boot picks the correct DTB on a subvolume root.btrfs-compsizetooling.Stack (merge bottom-up)
btrfs-foundation->dev(this PR)btrfs-profiles->btrfs-foundationcog-kodi-display->btrfs-profilesbuild-stamping->btrfs-profiles