pmb.install: add support for creating btrfs root filesystem (MR 2155)

in preparation for reversible upgrades, this change adds the option of
creating a btrfs root filesystem

pmb/config/__init__.py

@@ -164,7 +164,8 @@ locales = [
 ]
 
 # Supported filesystems and their fstools packages
-filesystems = {"ext2": "e2fsprogs",
+filesystems = {"btrfs": "btrfs-progs",
+               "ext2": "e2fsprogs",
                "ext4": "e2fsprogs",
                "f2fs": "f2fs-tools",
                "fat16": "dosfstools",

pmb/install/format.py

@@ -35,6 +35,9 @@ def format_and_mount_boot(args, boot_label):
     elif filesystem == "ext2":
         pmb.chroot.root(args, ["mkfs.ext2", "-F", "-q", "-L", boot_label,
                                device])
+    elif filesystem == "btrfs":
+        pmb.chroot.root(args, ["mkfs.btrfs", "-f", "-q", "-L", boot_label,
+                               device])
     else:
         raise RuntimeError("Filesystem " + filesystem + " is not supported!")
     pmb.chroot.root(args, ["mkdir", "-p", mountpoint])
@@ -106,6 +109,8 @@ def format_and_mount_root(args, device, root_label, sdcard):
                 mkfs_root_args = mkfs_root_args + ["-N", "100000"]
         elif filesystem == "f2fs":
             mkfs_root_args = ["mkfs.f2fs", "-f", "-l", root_label]
+        elif filesystem == "btrfs":
+            mkfs_root_args = ["mkfs.btrfs", "-f", "-L", root_label]
         else:
             raise RuntimeError(f"Don't know how to format {filesystem}!")
 

pmb/parse/arguments.py

@@ -162,7 +162,7 @@ def arguments_install(subparser):
     # Other
     group = ret.add_argument_group("other optional arguments")
     group.add_argument("--filesystem", help="root filesystem type",
-                       choices=["ext4", "f2fs"])
+                       choices=["ext4", "f2fs", "btrfs"])
 
 
 def arguments_export(subparser):