bugzilla 182057 - patch 3-1:
    Fixes directory delete out of memory error. Found in customer environment
    where gfs_inoded is deleting a max size of hash unit (0xffff entries). It
    hangs in leaf_free() during gmalloc while kmallocing 0xffff*sizeof(uint64_t)
    (=512K) of memroy. It did a kmalloc, zeroed out the buffer, then copied the
    zeroed contents into bh buffer and subsequently sent the bh into gfs_writei
    to write out to disk. This patch removes the unnecessary kmalloc plus the
    memory copy by directly zero out the bh buffer.