[LU-16313] PCC: change PCC type with bit matching for attach

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0
• Assignee: Qian Yingjin
• Reporter: Qian Yingjin

Description

We only support two PCC type: readonly and readwirte:

enum lu_pcc_type {
    LU_PCC_NONE = 0,
    LU_PCC_READWRITE,
    LU_PCC_READONLY,
    LU_PCC_MAX
};
struct lu_pcc_attach {
    __u32 pcca_type; /* PCC type */
    __u32 pcca_id; /* archive ID for readwrite, group ID for readonly */
};

The attach  data structure @lu_pcc_attach is using 32 bit @pcca_type to determine the type.

we could change it from "== LU_PCC_READWRITE" to "&LU_PCC_READWRITE" to determine the PCC type via 2 bit matching. The left bits can be used as other flags for PCC attach such the asynchronous attach via the command "lfs pcc attach -A".