XFS_WPC
if (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq)) {
XFS_WPC(wpc)->data_seq, XFS_DATA_FORK);
XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) {
XFS_WPC(wpc)->cow_seq, XFS_COW_FORK);
XFS_WPC(wpc)->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
XFS_WPC(wpc)->data_seq = READ_ONCE(ip->i_df.if_seq);
xfs_bmbt_to_iomap(ip, &wpc->iomap, &imap, 0, 0, XFS_WPC(wpc)->data_seq);
seq = &XFS_WPC(wpc)->cow_seq;
seq = &XFS_WPC(wpc)->data_seq;