Comment 15 for bug 392501

Looks like the kernel unconditionally aligns/pads to 8 bytes in the 64bit
interface. fs/readdir.c, filldir64() says:
   int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 1, sizeof(u64));

which means it looks like alignment needs to be forced in glibc too. I don't
think __attribute__ ((aligned (sizeof (__off64_t)))) is acceptable for
bits/dirent.h as that's a gcc extension. Thoughts?