[LU-8289] add ll_decode_linkea tool

• Type: New Feature
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.9.0
• Labels: patch
• Assignee: nasf (Inactive)
• Reporter: Qian Yingjin (Inactive)

Description

A MDT recovered by fsck might contain some files under lost+found
directory of ldiskfs. And in order to get the right path to move
them to, the xattr of trusted.link could be used to extract the
parent FIDs.

This path adds an new tool ll_decode_linkea to dump the parent FIDs
of a file.