[LU-12217] ll_migrate() vs truncate deadlock

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Severity: 3
• Assignee: Andriy Skulysh
• Reporter: Andriy Skulysh

Description

ll_migrate() takes inode_lock and sends OST_GETATTR
via ll_data_version(). The server sends BL AST to
a truncate on the same client to release osc lock
but it waits for the inode lock.
It's a wrong locking order beacause all osc operations
take ldlm locks before inode_lock.

inode_lock was added to protect from simultaneous migrates
from 1 client. But lli_lsm_sem is taken for parent,
so inode_lock isn't needed.