[LU-8049] Do not use LUSTRE_MSG_MAGIC to check local endianness

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.9.0
• Severity: 3
• Assignee: nasf (Inactive)
• Reporter: nasf (Inactive)

Description

There are some code using LUSTRE_MSG_MAGIC to check local endianness, such as:

void lustre_lma_swab(struct lustre_mdt_attrs *lma)
{
        /* Use LUSTRE_MSG_MAGIC to detect local endianess. */
        if (LUSTRE_MSG_MAGIC != cpu_to_le32(LUSTRE_MSG_MAGIC)) {
                __swab32s(&lma->lma_compat);
                __swab32s(&lma->lma_incompat);
                lustre_swab_lu_fid(&lma->lma_self_fid);
        }
};

It is not a good way of determining the CPU endianness, it is gratuitously confusing for no reason not only because it has nothing specific to do with LUSTRE_MSG_MAGIC, but also because this is a compile-time check that looks like a runtime check. Instead, we can fix it with checking "__BIG_ENDIAN".