[PATCH 23/26] xfs: refactor xfs_trans_apply_dquot_deltas

Darrick J. Wong
2020-07-15T01:55:13Z

Hoist the code that adjusts the incore quota reservation count
adjustments into a separate function, both to reduce the level of
indentation and also to reduce the amount of open-coded logic.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Collins <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/xfs_trans_dquot.c | 103 +++++++++++++++++++++-------------------------
1 file changed, 46 insertions(+), 57 deletions(-)

diff --git a/fs/xfs/xfs_trans_dquot.c b/fs/xfs/xfs_trans_dquot.c
index cce457ad220b..78201ff3696b 100644
--- a/fs/xfs/xfs_trans_dquot.c
+++ b/fs/xfs/xfs_trans_dquot.c
@@ -293,6 +293,37 @@ xfs_trans_dqlockedjoin(
}
}

+/* Apply dqtrx changes to the quota reservation counters. */
+static inline void
+xfs_apply_quota_reservation_deltas(
+ struct xfs_dquot_res *res,
+ uint64_t reserved,
+ int64_t res_used,
+ int64_t count_delta)
+{
+ if (reserved != 0) {
+ /*
+ * Subtle math here: If reserved > res_used (the normal case),
+ * we're simply subtracting the unused transaction quota
+ * reservation from the dquot reservation.
+ *
+ * If, however, res_used > reserved, then we have allocated
+ * more quota blocks than were reserved for the transaction.
+ * We must add that excess to the dquot reservation since it
+ * tracks (usage + resv) and by definition we didn't reserve
+ * that excess.
+ */
+ res->reserved -= abs(reserved - res_used);
+ } else if (count_delta != 0) {
+ /*
+ * These blks were never reserved, either inside a transaction
+ * or outside one (in a delayed allocation). Also, this isn't
+ * always a negative number since we sometimes deliberately
+ * skip quota reservations.
+ */
+ res->reserved += count_delta;
+ }
+}

/*
* Called by xfs_trans_commit() and similar in spirit to
@@ -327,6 +358,8 @@ xfs_trans_apply_dquot_deltas(
xfs_trans_dqlockedjoin(tp, qa);

for (i = 0; i < XFS_QM_TRANS_MAXDQS; i++) {
+ uint64_t blk_res_used;
+
qtrx = &qa[i];
/*
* The array of dquots is filled
@@ -396,71 +429,27 @@ xfs_trans_apply_dquot_deltas(
* In case of delayed allocations, there's no
* reservation that a transaction structure knows of.
*/
- if (qtrx->qt_blk_res != 0) {
- uint64_t blk_res_used = 0;
+ blk_res_used = max_t(int64_t, 0, qtrx->qt_bcount_delta);
+ xfs_apply_quota_reservation_deltas(&dqp->q_blk,
+ qtrx->qt_blk_res, blk_res_used,
+ qtrx->qt_bcount_delta);

- if (qtrx->qt_bcount_delta > 0)
- blk_res_used = qtrx->qt_bcount_delta;
-
- if (qtrx->qt_blk_res != blk_res_used) {
- if (qtrx->qt_blk_res > blk_res_used)
- dqp->q_blk.reserved -= (xfs_qcnt_t)
- (qtrx->qt_blk_res -
- blk_res_used);
- else
- dqp->q_blk.reserved -= (xfs_qcnt_t)
- (blk_res_used -
- qtrx->qt_blk_res);
- }
- } else {
- /*
- * These blks were never reserved, either inside
- * a transaction or outside one (in a delayed
- * allocation). Also, this isn't always a
- * negative number since we sometimes
- * deliberately skip quota reservations.
- */
- if (qtrx->qt_bcount_delta) {
- dqp->q_blk.reserved +=
- (xfs_qcnt_t)qtrx->qt_bcount_delta;
- }
- }
/*
* Adjust the RT reservation.
*/
- if (qtrx->qt_rtblk_res != 0) {
- if (qtrx->qt_rtblk_res != qtrx->qt_rtblk_res_used) {
- if (qtrx->qt_rtblk_res >
- qtrx->qt_rtblk_res_used)
- dqp->q_rtb.reserved -= (xfs_qcnt_t)
- (qtrx->qt_rtblk_res -
- qtrx->qt_rtblk_res_used);
- else
- dqp->q_rtb.reserved -= (xfs_qcnt_t)
- (qtrx->qt_rtblk_res_used -
- qtrx->qt_rtblk_res);
- }
- } else {
- if (qtrx->qt_rtbcount_delta)
- dqp->q_rtb.reserved +=
- (xfs_qcnt_t)qtrx->qt_rtbcount_delta;
- }
+ xfs_apply_quota_reservation_deltas(&dqp->q_rtb,
+ qtrx->qt_rtblk_res,
+ qtrx->qt_rtblk_res_used,
+ qtrx->qt_rtbcount_delta);

/*
* Adjust the inode reservation.
*/
- if (qtrx->qt_ino_res != 0) {
- ASSERT(qtrx->qt_ino_res >=
- qtrx->qt_ino_res_used);
- if (qtrx->qt_ino_res > qtrx->qt_ino_res_used)
- dqp->q_ino.reserved -= (xfs_qcnt_t)
- (qtrx->qt_ino_res -
- qtrx->qt_ino_res_used);
- } else {
- if (qtrx->qt_icount_delta)
- dqp->q_ino.reserved +=
- (xfs_qcnt_t)qtrx->qt_icount_delta;
- }
+ ASSERT(qtrx->qt_ino_res >= qtrx->qt_ino_res_used);
+ xfs_apply_quota_reservation_deltas(&dqp->q_ino,
+ qtrx->qt_ino_res,
+ qtrx->qt_ino_res_used,
+ qtrx->qt_icount_delta);

ASSERT(dqp->q_blk.reserved >= dqp->q_blk.count);
ASSERT(dqp->q_ino.reserved >= dqp->q_ino.count);