[LU-7205] OSP sync RPC could be out of order

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.8.0
• Severity: 3
• Assignee: Niu Yawei (Inactive)
• Reporter: Niu Yawei (Inactive)

Description

Current Lustre doesn't have a mechanism to make sure the RPCs generated when processing OSP sync log arrive OST in order, so if there are two adjacent & depended records (such as two chown operations) in the log, the RPCs for these two records may arrive OST in wrong order, that leads to unexpected inconsistency or failure.

A quick solution could be restricting the inflight RPC to 1, and use OUT to combine many operations in a single RPC.