ext4: migrate cleanup

This patch cleanup code a bit, actual logic not changed
- Move current block pointer to migrate_structure, let's all
  walk info will be in one structure.
- Get rid of usless null ind-block ptr checks, caller already
  does that check.

Signed-off-by: Dmitry Monakhov <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
1 file changed