[LU-3590] Repair the file which MDT-object has dangling reference

• Type: Technical task
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.6.0
• Assignee: nasf (Inactive)
• Reporter: Richard Henwood (Inactive)

Description

There are two cases for dangling reference:

1. A formerly allocated OST-object is lost. The LFSCK will allocate new OST-object with the specified object external FID and initialize it with the given parent MDT-object FID and owner attributes. Although the new created OST-object is initialized, the SUID + SGID mode will be kept, which will be dropped by the first modification RPC, like write/punch/setattr. Then we can distinguish whether the new create OST-object has been modified or not.
2. The OST-object is there, but it is not initialized, and without SUID + SGID mode set. Then the LFSCK will initialize it with the given parent MDT-object FID and owner attributes.