[LU-4368] lustre_user.h calls offsetof() with non-constant expression

• Type: Bug
• Resolution: Duplicate
• Priority: Minor
• Severity: 3
• Assignee: WC Triage
• Reporter: Ned Bass

Description

GCC supports offsetof() on non-constant expressions but in general this is compiler-dependent behavior. In particular, the IBM XLC does not support it. Since luster_user.h may be used by user applications, we should try to make the header as portable as possible.

This is the function:

/** Compute the current length of the provided hsm_user_request. */
static inline int hur_len(struct hsm_user_request *hur)
{
        return offsetof(struct hsm_user_request,
                        hur_user_item[hur->hur_request.hr_itemcount]) +
                hur->hur_request.hr_data_len;
}

Building the header with the IBM compilers produces this error:

"/usr/local/tools/liblustre/include/lustre/lustre_user.h", line 1006.55: 1506-307 (S) Array index must be a constant expression in the offsetof macro.