xfs: clean up dqblk extraction

Since the introduction of xfs_dqblk in V5, xfs really ought to find the
dqblk pointer from the dquot buffer, then compute the xfs_disk_dquot
pointer from the dqblk pointer.  Fix the open-coded xfs_buf_offset calls
and do the type checking in the correct order.

Note that this has made no practical difference since the start of the
xfs_disk_dquot is coincident with the start of the xfs_dqblk.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

fs/xfs/xfs_dquot.c

@@ -562,7 +562,8 @@ xfs_dquot_from_disk(
 	struct xfs_dquot	*dqp,
 	struct xfs_buf		*bp)
 {
-	struct xfs_disk_dquot	*ddqp = bp->b_addr + dqp->q_bufoffset;
+	struct xfs_dqblk	*dqb = xfs_buf_offset(bp, dqp->q_bufoffset);
+	struct xfs_disk_dquot	*ddqp = &dqb->dd_diskdq;
 
 	/*
 	 * Ensure that we got the type and ID we were looking for.
@@ -1250,7 +1251,7 @@ xfs_qm_dqflush(
 	}
 
 	/* Flush the incore dquot to the ondisk buffer. */
-	dqblk = bp->b_addr + dqp->q_bufoffset;
+	dqblk = xfs_buf_offset(bp, dqp->q_bufoffset);
 	xfs_dquot_to_disk(&dqblk->dd_diskdq, dqp);
 
 	/*

fs/xfs/xfs_dquot_item_recover.c

@@ -65,6 +65,7 @@ xlog_recover_dquot_commit_pass2(
 {
 	struct xfs_mount		*mp = log->l_mp;
 	struct xfs_buf			*bp;
+	struct xfs_dqblk		*dqb;
 	struct xfs_disk_dquot		*ddq, *recddq;
 	struct xfs_dq_logformat		*dq_f;
 	xfs_failaddr_t			fa;
@@ -130,14 +131,14 @@ xlog_recover_dquot_commit_pass2(
 		return error;
 
 	ASSERT(bp);
-	ddq = xfs_buf_offset(bp, dq_f->qlf_boffset);
+	dqb = xfs_buf_offset(bp, dq_f->qlf_boffset);
+	ddq = &dqb->dd_diskdq;
 
 	/*
 	 * If the dquot has an LSN in it, recover the dquot only if it's less
 	 * than the lsn of the transaction we are replaying.
 	 */
 	if (xfs_has_crc(mp)) {
-		struct xfs_dqblk *dqb = (struct xfs_dqblk *)ddq;
 		xfs_lsn_t	lsn = be64_to_cpu(dqb->dd_lsn);
 
 		if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
@@ -147,7 +148,7 @@ xlog_recover_dquot_commit_pass2(
 
 	memcpy(ddq, recddq, item->ri_buf[1].i_len);
 	if (xfs_has_crc(mp)) {
-		xfs_update_cksum((char *)ddq, sizeof(struct xfs_dqblk),
+		xfs_update_cksum((char *)dqb, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF);
 	}