Assemble array with write journal

Assemble array with write journal

Example output:

./mdadm --assemble /dev/md0 /dev/sd[c-f] /dev/sdb1
mdadm: /dev/md0 has been started with 4 drives and 1 journal.

mdadm checks superblock for journal devices. If the journal device
is missing or faulty, mdadm will show warning

./mdadm --assemble /dev/md0 /dev/sd[c-q] /dev/sdb1
mdadm: Not safe to assemble with missing or stale journal device, consider --force.

User can insist to start the array (read only) with --force

./mdadm --assemble /dev/md0 /dev/sd[c-q] /dev/sdb1 --force
mdadm: Journal is missing or stale, starting array read only.
mdadm: /dev/md0 has been started with 15 drives.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>