[LU-3257] IO framework and Readonly replication file

• Type: Technical task
• Resolution: Duplicate
• Priority: Minor
• Affects Version/s: Lustre 2.5.0
• Assignee: Jinshan Xiong (Inactive)
• Reporter: Jinshan Xiong (Inactive)

Description

Revise CLIO to support read only replication file.

The following features will be implemented in this task:
1. timeout IO RPC support
2. IO framework to try next replica to fetch data
3. policy to choose replica to serve read
4. dynamic cl_page. Fanout page won't be implemented in this phase, but dynamic cl_page, which can link a top page to different sub page by replica selection has to be worked out.