ext4_grp_offs_to_block
start = ext4_grp_offs_to_block(ac->ac_sb, &ex);
block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
if (ext4_grp_offs_to_block(ac->ac_sb, &ac->ac_g_ex) != start)
goal_block = ext4_grp_offs_to_block(ac->ac_sb, &ac->ac_g_ex);
pa->pa_pstart = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
pa->pa_pstart = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);