tree 6bb85c43bfd100b0a220c788c654f2f74ca553e4
parent cece552074c591970353ad48308d65f110aeaf28
author Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> 1239069719 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1239118280 -0700

nilfs2: introduce secondary super block

The former versions didn't have extra super blocks.  This improves the
weak point by introducing another super block at unused region in tail of
the partition.

This doesn't break disk format compatibility; older versions just ingore
the secondary super block, and new versions just recover it if it doesn't
exist.  The partition created by an old mkfs may not have unused region,
but in that case, the secondary super block will not be added.

This doesn't make more redundant copies of the super block; it is a future
work.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>