Linux 7.3-rc4 To Address Two Unfortunate Bugs With Btrfs

Merged today were this week's set of Btrfs file-system fixes for the Linux 7.3-rc4 kernel, which include two notable bug fixes.

First up is a regression introduced back in Linux 7.2-rc1 and present until now due to a change with how the fs_fsid identifier was derived. But this in turn broke backwards compatibility, including for user-space applications, since the f_fsid can change after a kernel update and shift across reboots. For apps that expect a stable ID, this broke programs like applications relying on the FSID to encrypt/decrypt VPN key files. This broke NetworkManager OpenConnect for instance when users on Btrfs upgraded to Linux 7.2 with no longer having VPN access. So for Linux 7.3-rc4, the FSID is back to being derived from the file-system UUID instead.

The other major Btrfs fix this week was just present in the Linux 7.3 development cycle thus far and it broken detection of /dev/root with handling for booting of initramdisk-less systems with GRUB2. GRUB2 on Linux 7.3 until now with Btrfs root file-systems was not able to detect the root file-system device when no initramfs was present.

Those fixes along with some more typical Btrfs file-system fixes were merged today ahead of the Linux 7.3-rc4 release on Sunday.