fsck.ubifs: Distinguish reasons when certain failures happen

fsck.ubifs: Distinguish reasons when certain failures happen

Read failure caused by scanning corrupted data or invalid data members
should be identified, because fsck can handle it. Updating lp failure
caused by bad space statistics should be identified too, because fsck
can handle it.
Add eight callback functions to implement it for fsck:
1. set_failure_reason_callback: Record failure reasons when reading or
   parsing node failed, there are four reasons:
   a. FR_DATA_CORRUPTED: scanning corrupted data or invalid nodes found
   b. FR_TNC_CORRUPTED: invalid index nodes
   c. FR_LPT_CORRUPTED: invalid pnode/nnode
   d. FR_LPT_INCORRECT: invalid space statistics or invalid LEB properties
2. get_failure_reason_callback: get failure reasons
3. clear_failure_reason_callback: Clear the error which is caused by
   above reasons.
4. test_and_clear_failure_reason_callback: Check and clear the error
   which is caused by above reasons, if so, fsck will handle it
   according to specific situation.
   For example, fsck will drop data node rather than fails to return
   when reading failure is caused by DATA_CORRUPTED.
   For another example, journal replaying will continue rather than
   fails to return if updating lpt failure is caused by LPT_CORRUPTED.
5. set_lpt_invalid_callback: Set the invalid lpt status
6. test_lpt_valid_callback: Check whether the lpt is corrupted/incorrect,
   it should be invoked before updating lp, if lpt status is invalid,
   returns false (which means that caller should skip updating lp, because
   updating lp could trigger assertion failed in ubifs_change_lp).
7. can_ignore_failure_callback: Check whether the failure can be
   ignored, some inconsistent errors won't affect the fsck process,
   for example wrong space statistics can be fixed after traversing
   TNC, so failures caused by incorrect space statistics can be ignored.
8. handle_failure_callback: Check whether the failure can be handled,
   some inconsistent errors could be fixed by fsck, we have fix_problem
   to do that, but UBIFS needs a callback function to invoke it in common
   libs.

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>