[LU-11104] rename under striped directory may cause deadlock

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.12.0
• Labels: dne2
• Severity: 3
• Assignee: Lai Siyao
• Reporter: Lai Siyao

Description

In rename locking, there are two situations we need to lock target
parent before source parent:
1. source parent is subdir of target parent.
2. source and target parents are both stripes of the same directory,
and stripe index of source parent is after that of target parent.

But the check for the second situation is missing, which may cause
deadlock if another thread is taking stripe locks of their parent.

Issue Links

• is related to: LU-6297 Move rename is_subdir check from MDD to MDT
• is related to: LU-4911 Using wrong attr inside mdd_is_subdir
• is related to: LU-11082 stuck threads on MDS