static void ext4_mb_use_group_pa(struct ext4_allocation_context *ac,
				struct ext4_prealloc_space *pa)
{
	unsigned int len = ac->ac_o_ex.fe_len;

	ext4_get_group_no_and_offset(ac->ac_sb, pa->pa_pstart,
					&ac->ac_b_ex.fe_group,
					&ac->ac_b_ex.fe_start);
	ac->ac_b_ex.fe_len = len;
	ac->ac_status = AC_STATUS_FOUND;
	ac->ac_pa = pa;

	/* we don't correct pa_pstart or pa_plen here to avoid
	 * possible race when the group is being loaded concurrently
	 * instead we correct pa later, after blocks are marked
	 * in on-disk bitmap -- see ext4_mb_release_context()
	 * Other CPUs are prevented from allocating from this pa by lg_mutex
	 */
	mb_debug(ac->ac_sb, "use %u/%u from group pa %p\n",
		 pa->pa_lstart-len, len, pa);
}
static void ext4_mb_use_group_pa(struct ext4_allocation_context *ac,
				struct ext4_prealloc_space *pa)
{
	unsigned int len = ac->ac_o_ex.fe_len;

	ext4_get_group_no_and_offset(ac->ac_sb, pa->pa_pstart,
					&ac->ac_b_ex.fe_group,
					&ac->ac_b_ex.fe_start);
	ac->ac_b_ex.fe_len = len;
	ac->ac_status = AC_STATUS_FOUND;
	ac->ac_pa = pa;

	 
	mb_debug(ac->ac_sb, "use %u/%u from group pa %p\n",
		 pa->pa_lstart-len, len, pa);
}