f2fs: introduce and spread verify_blkaddr

commit e1da7872f6eda977bd812346bf588c35e4495a1e upstream.

This patch introduces verify_blkaddr to check meta/data block address
with valid range to detect bug earlier.

In addition, once we encounter an invalid blkaddr, notice user to run
fsck to fix, and let the kernel panic.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
[bwh: Backported to 4.9:
 - I skipped an earlier renaming of is_valid_meta_blkaddr() to
   f2fs_is_valid_meta_blkaddr()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>