Hardcoding of ext3 as partman's default filesystem

[Colin Watson <cjwatson@debian.org>]

There are a number of places in partman where the default filesystem is
currently hardcoded:

  partman-auto-lvm/lib/auto-lvm.sh:17:    echo "$scheme${NL}100 1000 -1 ext3 \$primary{ } method{ $method }"
  partman-crypto/init.d/crypto:108:                       filesystem=ext3
  partman-crypto/init.d/crypto:131:               ext3)
  partman-partitioning/free_space/new/do_option:148:      if [ "$id" ] && [ -f ../../ext3 ]; then
  partman-partitioning/free_space/new/do_option:154:              echo ext3 >$id/filesystem
  partman-partitioning/free_space/new/do_option:156:              if [ -f /lib/partman/mountoptions/ext3_defaults ]; then
  partman-partitioning/free_space/new/do_option:157:                      for op in $(cat /lib/partman/mountoptions/ext3_defaults); do
  partman-partitioning/free_space/new/do_option:188:              menudir_default_choice /lib/partman/active_partition ext3 mountpoint || true

... and of course all the recipes in partman-auto. Particularly with the
advent of ext4 (where I'd like to be able to offer an easy way to
autopartition with ext4 without having to go through manual
partitioning, until such time as it's made the default), I was wondering
about abstracting this a bit.

How about a partman/default_filesystem template in partman-base,
defaulting to ext3, and then a $default expansion in the filesystem
field in partitioning recipes? That would make it a matter of a boot
parameter to change the default filesystem, and would make the code a
bit more elegant IMO.

(I'm happy to implement this after consensus, obviously.)

-- 
Colin Watson                                       [cjwatson@debian.org]