fsck.f2fs: update curseg .next_blkoff/.alloc_type preferential

If .next_blkoff is inconsistent, we can update curseg .next_blkoff
to first unused block address, and change .alloc_type to SSR
preferential, instead of move curseg to other position.

This can help to repair fuzzed image which has no more free segment.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
3 files changed