Add a new source command line argument which specifies the directory
tree that will be copied onto the newly formatted bcachefs filesystem.
This commit also fixes an issue in copy_link where uninitialized data is
copied into the symlink because of a round_up of the buffer size.
Signed-off-by: Ariel Miculas <ariel.miculas@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
