In many cases, the statically sized 64MB journal is far below the
e2fstools default calculation[0] which calls for a 64MB journal only
on filesystems smaller than 16GB. On bare metal in particular, the
correct default journal size will often be in the 512MB-1GB range.
Since we cannot know what the target system is, this should be a
tunable parameter that the user can set depending on the intended
image usage.
Add a DIB_JOURNAL_SIZE envvar and --mkfs-journal-size parameter
to the image creation so users can override the default journal
size.
[0] https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/tree/lib/ext2fs/mkjournal.c#n333
Change-Id: I65fa13a088eecdfe61636678578577ea2cfb3c0c
11142f75b4