xfs: use a per-resource struct for incore dquot data

Introduce a new struct xfs_dquot_res that we'll use to track all the
incore data for a particular resource type (block, inode, rt block).
This will help us (once we've eliminated q_core) to declutter quota
functions that currently open-code field access or pass around fields
around explicitly.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>

fs/xfs/xfs_dquot.c

@@ -552,9 +552,9 @@ xfs_dquot_from_disk(
 	 * Reservation counters are defined as reservation plus current usage
 	 * to avoid having to add every time.
 	 */
-	dqp->q_res_bcount = be64_to_cpu(ddqp->d_bcount);
-	dqp->q_res_icount = be64_to_cpu(ddqp->d_icount);
-	dqp->q_res_rtbcount = be64_to_cpu(ddqp->d_rtbcount);
+	dqp->q_blk.reserved = be64_to_cpu(ddqp->d_bcount);
+	dqp->q_ino.reserved = be64_to_cpu(ddqp->d_icount);
+	dqp->q_rtb.reserved = be64_to_cpu(ddqp->d_rtbcount);
 
 	/* initialize the dquot speculative prealloc thresholds */
 	xfs_dquot_set_prealloc_limits(dqp);