[PATCH 06/17] xfs: remove xfs_qm_dqput and optimize dropping dquot references

[Christoph Hellwig <hch@lst.de>]

With the new lockref-based dquot reference counting, there is no need to
hold q_qlock for dropping the reference.  Make xfs_qm_dqrele the main
function to drop dquot references without taking q_qlock and convert all
callers of xfs_qm_dqput to unlock q_qlock and call xfs_qm_dqrele instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/scrub/quota.c      |  3 ++-
 fs/xfs/scrub/quotacheck.c |  6 ++++--
 fs/xfs/xfs_dquot.c        | 45 ++++++++-------------------------------
 fs/xfs/xfs_dquot.h        |  1 -
 fs/xfs/xfs_qm.c           |  7 ++++--
 fs/xfs/xfs_qm_bhv.c       |  3 ++-
 fs/xfs/xfs_qm_syscalls.c  |  6 ++++--
 fs/xfs/xfs_trace.h        |  3 +--
 8 files changed, 27 insertions(+), 47 deletions(-)

diff --git a/fs/xfs/scrub/quota.c b/fs/xfs/scrub/quota.c
index c78cf9f96cf6..cfcd0fb66845 100644
--- a/fs/xfs/scrub/quota.c
+++ b/fs/xfs/scrub/quota.c
@@ -330,7 +330,8 @@ xchk_quota(
 	xchk_dqiter_init(&cursor, sc, dqtype);
 	while ((error = xchk_dquot_iter(&cursor, &dq)) == 1) {
 		error = xchk_quota_item(&sqi, dq);
-		xfs_qm_dqput(dq);
+		mutex_unlock(&dq->q_qlock);
+		xfs_qm_dqrele(dq);
 		if (error)
 			break;
 	}
diff --git a/fs/xfs/scrub/quotacheck.c b/fs/xfs/scrub/quotacheck.c
index e4105aaafe84..180449f654f6 100644
--- a/fs/xfs/scrub/quotacheck.c
+++ b/fs/xfs/scrub/quotacheck.c
@@ -636,7 +636,8 @@ xqcheck_walk_observations(
 			return error;
 
 		error = xqcheck_compare_dquot(xqc, dqtype, dq);
-		xfs_qm_dqput(dq);
+		mutex_unlock(&dq->q_qlock);
+		xfs_qm_dqrele(dq);
 		if (error)
 			return error;
 
@@ -674,7 +675,8 @@ xqcheck_compare_dqtype(
 	xchk_dqiter_init(&cursor, sc, dqtype);
 	while ((error = xchk_dquot_iter(&cursor, &dq)) == 1) {
 		error = xqcheck_compare_dquot(xqc, dqtype, dq);
-		xfs_qm_dqput(dq);
+		mutex_unlock(&dq->q_qlock);
+		xfs_qm_dqrele(dq);
 		if (error)
 			break;
 	}
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index e53dffe2dcab..ceddbbb41999 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -1100,62 +1100,35 @@ xfs_qm_dqget_next(
 			return 0;
 		}
 
-		xfs_qm_dqput(dqp);
+		mutex_unlock(&dqp->q_qlock);
+		xfs_qm_dqrele(dqp);
 	}
 
 	return error;
 }
 
 /*
- * Release a reference to the dquot (decrement ref-count) and unlock it.
- *
- * If there is a group quota attached to this dquot, carefully release that
- * too without tripping over deadlocks'n'stuff.
+ * Release a reference to the dquot.
  */
 void
-xfs_qm_dqput(
+xfs_qm_dqrele(
 	struct xfs_dquot	*dqp)
 {
-	ASSERT(XFS_DQ_IS_LOCKED(dqp));
+	if (!dqp)
+		return;
 
-	trace_xfs_dqput(dqp);
+	trace_xfs_dqrele(dqp);
 
 	if (lockref_put_or_lock(&dqp->q_lockref))
-		goto out_unlock;
-
+		return;
 	if (!--dqp->q_lockref.count) {
 		struct xfs_quotainfo	*qi = dqp->q_mount->m_quotainfo;
-		trace_xfs_dqput_free(dqp);
 
+		trace_xfs_dqrele_free(dqp);
 		if (list_lru_add_obj(&qi->qi_lru, &dqp->q_lru))
 			XFS_STATS_INC(dqp->q_mount, xs_qm_dquot_unused);
 	}
 	spin_unlock(&dqp->q_lockref.lock);
-out_unlock:
-	mutex_unlock(&dqp->q_qlock);
-}
-
-/*
- * Release a dquot. Flush it if dirty, then dqput() it.
- * dquot must not be locked.
- */
-void
-xfs_qm_dqrele(
-	struct xfs_dquot	*dqp)
-{
-	if (!dqp)
-		return;
-
-	trace_xfs_dqrele(dqp);
-
-	mutex_lock(&dqp->q_qlock);
-	/*
-	 * We don't care to flush it if the dquot is dirty here.
-	 * That will create stutters that we want to avoid.
-	 * Instead we do a delayed write when we try to reclaim
-	 * a dirty dquot. Also xfs_sync will take part of the burden...
-	 */
-	xfs_qm_dqput(dqp);
 }
 
 /*
diff --git a/fs/xfs/xfs_dquot.h b/fs/xfs/xfs_dquot.h
index c56fbc39d089..bbb824adca82 100644
--- a/fs/xfs/xfs_dquot.h
+++ b/fs/xfs/xfs_dquot.h
@@ -218,7 +218,6 @@ int		xfs_qm_dqget_next(struct xfs_mount *mp, xfs_dqid_t id,
 int		xfs_qm_dqget_uncached(struct xfs_mount *mp,
 				xfs_dqid_t id, xfs_dqtype_t type,
 				struct xfs_dquot **dqpp);
-void		xfs_qm_dqput(struct xfs_dquot *dqp);
 
 void		xfs_dqlock2(struct xfs_dquot *, struct xfs_dquot *);
 void		xfs_dqlockn(struct xfs_dqtrx *q);
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 0d2243d549ad..9bd7068b9e5a 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -1345,7 +1345,9 @@ xfs_qm_quotacheck_dqadjust(
 	}
 
 	dqp->q_flags |= XFS_DQFLAG_DIRTY;
-	xfs_qm_dqput(dqp);
+	mutex_unlock(&dqp->q_qlock);
+
+	xfs_qm_dqrele(dqp);
 	return 0;
 }
 
@@ -1486,7 +1488,8 @@ xfs_qm_flush_one(
 		xfs_buf_delwri_queue(bp, buffer_list);
 	xfs_buf_relse(bp);
 out_unlock:
-	xfs_qm_dqput(dqp);
+	mutex_unlock(&dqp->q_qlock);
+	xfs_qm_dqrele(dqp);
 	return error;
 }
 
diff --git a/fs/xfs/xfs_qm_bhv.c b/fs/xfs/xfs_qm_bhv.c
index 245d754f382a..e5a30b12253c 100644
--- a/fs/xfs/xfs_qm_bhv.c
+++ b/fs/xfs/xfs_qm_bhv.c
@@ -74,7 +74,8 @@ xfs_qm_statvfs(
 
 	if (!xfs_qm_dqget(mp, ip->i_projid, XFS_DQTYPE_PROJ, false, &dqp)) {
 		xfs_fill_statvfs_from_dquot(statp, ip, dqp);
-		xfs_qm_dqput(dqp);
+		mutex_unlock(&dqp->q_qlock);
+		xfs_qm_dqrele(dqp);
 	}
 }
 
diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c
index 59ef382900fe..441f9806cddb 100644
--- a/fs/xfs/xfs_qm_syscalls.c
+++ b/fs/xfs/xfs_qm_syscalls.c
@@ -467,7 +467,8 @@ xfs_qm_scall_getquota(
 	xfs_qm_scall_getquota_fill_qc(mp, type, dqp, dst);
 
 out_put:
-	xfs_qm_dqput(dqp);
+	mutex_unlock(&dqp->q_qlock);
+	xfs_qm_dqrele(dqp);
 	return error;
 }
 
@@ -497,7 +498,8 @@ xfs_qm_scall_getquota_next(
 	*id = dqp->q_id;
 
 	xfs_qm_scall_getquota_fill_qc(mp, type, dqp, dst);
+	mutex_unlock(&dqp->q_qlock);
 
-	xfs_qm_dqput(dqp);
+	xfs_qm_dqrele(dqp);
 	return error;
 }
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 46d21eb11ccb..fccc032b3c6c 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1409,9 +1409,8 @@ DEFINE_DQUOT_EVENT(xfs_dqget_hit);
 DEFINE_DQUOT_EVENT(xfs_dqget_miss);
 DEFINE_DQUOT_EVENT(xfs_dqget_freeing);
 DEFINE_DQUOT_EVENT(xfs_dqget_dup);
-DEFINE_DQUOT_EVENT(xfs_dqput);
-DEFINE_DQUOT_EVENT(xfs_dqput_free);
 DEFINE_DQUOT_EVENT(xfs_dqrele);
+DEFINE_DQUOT_EVENT(xfs_dqrele_free);
 DEFINE_DQUOT_EVENT(xfs_dqflush);
 DEFINE_DQUOT_EVENT(xfs_dqflush_force);
 DEFINE_DQUOT_EVENT(xfs_dqflush_done);
-- 
2.47.3