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From:   Logan Gunthorpe <logang@deltatee.com>
To:     linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
        Song Liu <song@kernel.org>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Donald Buczek <buczek@molgen.mpg.de>,
        Guoqing Jiang <guoqing.jiang@linux.dev>,
        Xiao Ni <xni@redhat.com>, Stephen Bates <sbates@raithlin.com>,
        Martin Oliveira <Martin.Oliveira@eideticom.com>,
        David Sloan <David.Sloan@eideticom.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Christoph Hellwig <hch@lst.de>
Date:   Thu, 26 May 2022 10:35:52 -0600
Message-Id: <20220526163604.32736-6-logang@deltatee.com>
In-Reply-To: <20220526163604.32736-1-logang@deltatee.com>
References: <20220526163604.32736-1-logang@deltatee.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Subject: [PATCH v2 05/17] md/raid5-cache: Refactor r5l_wake_reclaim() to take a struct r5conf
Precedence: bulk

All calls to r5l_wake_reclaim() have to dereference conf to get the
log. The log pointer should be protected by RCU, but isn't. Push
the dereference of conf->log into r5l_wake_reclaim() to reduce
the number of sites that dereference conf->log so this can be improved.

No functional changes intended.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/raid5-cache.c | 41 +++++++++++++++++++++-------------------
 drivers/md/raid5-log.h   |  2 +-
 drivers/md/raid5.c       |  2 +-
 3 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index edff4e8d07dc..3427f95cb358 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -326,7 +326,20 @@ void r5c_handle_cached_data_endio(struct r5conf *conf,
 	}
 }
 
-void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
+static void __r5l_wake_reclaim(struct r5l_log *log, sector_t space)
+{
+	unsigned long target;
+	unsigned long new = (unsigned long)space; /* overflow in theory */
+
+	if (!log)
+		return;
+	do {
+		target = log->reclaim_target;
+		if (new < target)
+			return;
+	} while (cmpxchg(&log->reclaim_target, target, new) != target);
+	md_wakeup_thread(log->reclaim_thread);
+}
 
 /* Check whether we should flush some stripes to free up stripe cache */
 void r5c_check_stripe_cache_usage(struct r5conf *conf)
@@ -349,7 +362,7 @@ void r5c_check_stripe_cache_usage(struct r5conf *conf)
 	 */
 	if (total_cached > conf->min_nr_stripes * 1 / 2 ||
 	    atomic_read(&conf->empty_inactive_list_nr) > 0)
-		r5l_wake_reclaim(conf->log, 0);
+		__r5l_wake_reclaim(conf->log, 0);
 }
 
 /*
@@ -368,7 +381,7 @@ void r5c_check_cached_full_stripe(struct r5conf *conf)
 	if (atomic_read(&conf->r5c_cached_full_stripes) >=
 	    min(R5C_FULL_STRIPE_FLUSH_BATCH(conf),
 		conf->chunk_sectors >> RAID5_STRIPE_SHIFT(conf)))
-		r5l_wake_reclaim(conf->log, 0);
+		__r5l_wake_reclaim(conf->log, 0);
 }
 
 /*
@@ -444,7 +457,7 @@ static inline void r5c_update_log_state(struct r5l_log *log)
 		clear_bit(R5C_LOG_TIGHT, &conf->cache_state);
 
 	if (wake_reclaim)
-		r5l_wake_reclaim(log, 0);
+		__r5l_wake_reclaim(log, 0);
 }
 
 /*
@@ -1087,7 +1100,7 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)
 
 	mutex_unlock(&log->io_mutex);
 	if (wake_reclaim)
-		r5l_wake_reclaim(log, reserve);
+		__r5l_wake_reclaim(log, reserve);
 	return 0;
 }
 
@@ -1239,7 +1252,7 @@ static void __r5l_stripe_write_finished(struct r5l_io_unit *io)
 
 	if (r5l_reclaimable_space(log) > log->max_free_space ||
 	    test_bit(R5C_LOG_TIGHT, &conf->cache_state))
-		r5l_wake_reclaim(log, 0);
+		__r5l_wake_reclaim(log, 0);
 
 	spin_unlock_irqrestore(&log->io_list_lock, flags);
 	wake_up(&log->iounit_wait);
@@ -1564,19 +1577,9 @@ static void r5l_reclaim_thread(struct md_thread *thread)
 	r5l_do_reclaim(log);
 }
 
-void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
+void r5l_wake_reclaim(struct r5conf *conf, sector_t space)
 {
-	unsigned long target;
-	unsigned long new = (unsigned long)space; /* overflow in theory */
-
-	if (!log)
-		return;
-	do {
-		target = log->reclaim_target;
-		if (new < target)
-			return;
-	} while (cmpxchg(&log->reclaim_target, target, new) != target);
-	md_wakeup_thread(log->reclaim_thread);
+	__r5l_wake_reclaim(conf->log, space);
 }
 
 void r5l_quiesce(struct r5l_log *log, int quiesce)
@@ -1588,7 +1591,7 @@ void r5l_quiesce(struct r5l_log *log, int quiesce)
 		mddev = log->rdev->mddev;
 		wake_up(&mddev->sb_wait);
 		kthread_park(log->reclaim_thread->tsk);
-		r5l_wake_reclaim(log, MaxSector);
+		__r5l_wake_reclaim(log, MaxSector);
 		r5l_do_reclaim(log);
 	} else
 		kthread_unpark(log->reclaim_thread->tsk);
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index 5ace25d11ea4..7594d2d80520 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -18,7 +18,7 @@ void r5c_finish_stripe_write_out(struct r5conf *conf, struct stripe_head *sh,
 				 struct stripe_head_state *s);
 void r5c_release_extra_page(struct stripe_head *sh);
 void r5c_use_extra_page(struct stripe_head *sh);
-void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
+void r5l_wake_reclaim(struct r5conf *conf, sector_t space);
 void r5c_handle_cached_data_endio(struct r5conf *conf,
 				  struct stripe_head *sh, int disks);
 int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f1b55495de53..0d486f8aaf87 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -742,7 +742,7 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
 			if (!sh) {
 				set_bit(R5_INACTIVE_BLOCKED,
 					&conf->cache_state);
-				r5l_wake_reclaim(conf->log, 0);
+				r5l_wake_reclaim(conf, 0);
 				wait_event_lock_irq(
 					conf->wait_for_stripe,
 					!list_empty(conf->inactive_list + hash) &&
-- 
2.30.2