linux-kernel - [PATCH v2 04/17] md/raid5-cache: Refactor r5l_flush_stripe_to

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Message-Id: <20220526163604.32736-5-logang@deltatee.com>
Date:   Thu, 26 May 2022 10:35:51 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
        Song Liu <song@...nel.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Donald Buczek <buczek@...gen.mpg.de>,
        Guoqing Jiang <guoqing.jiang@...ux.dev>,
        Xiao Ni <xni@...hat.com>, Stephen Bates <sbates@...thlin.com>,
        Martin Oliveira <Martin.Oliveira@...eticom.com>,
        David Sloan <David.Sloan@...eticom.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v2 04/17] md/raid5-cache: Refactor r5l_flush_stripe_to_raid() to take a struct r5conf

All calls to r5l_flush_stripe_to_raid() 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_flush_stripe_to_raid() 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@...tatee.com>
Reviewed-by: Christoph Hellwig <hch@....de>
---
 drivers/md/raid5-cache.c | 3 ++-
 drivers/md/raid5-log.h   | 4 ++--
 drivers/md/raid5.c       | 6 +++---
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 7c5dc45b1ea8..edff4e8d07dc 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1289,8 +1289,9 @@ static void r5l_log_flush_endio(struct bio *bio)
  * only write stripes of an io_unit to raid disks till the io_unit is the first
  * one whose data/parity is in log.
  */
-void r5l_flush_stripe_to_raid(struct r5l_log *log)
+void r5l_flush_stripe_to_raid(struct r5conf *conf)
 {
+	struct r5l_log *log = conf->log;
 	bool do_flush;
 
 	if (!log || !log->need_cache_flush)
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index db4c1262b380..5ace25d11ea4 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -6,7 +6,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev);
 void r5l_exit_log(struct r5conf *conf);
 int r5l_write_stripe(struct r5l_log *log, struct stripe_head *head_sh);
 void r5l_write_stripe_run(struct r5l_log *log);
-void r5l_flush_stripe_to_raid(struct r5l_log *log);
+void r5l_flush_stripe_to_raid(struct r5conf *conf);
 void r5l_stripe_write_finished(struct stripe_head *sh);
 int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio);
 void r5l_quiesce(struct r5l_log *log, int quiesce);
@@ -96,7 +96,7 @@ static inline void log_write_stripe_run(struct r5conf *conf)
 static inline void log_flush_stripe_to_raid(struct r5conf *conf)
 {
 	if (conf->log)
-		r5l_flush_stripe_to_raid(conf->log);
+		r5l_flush_stripe_to_raid(conf);
 	else if (raid5_has_ppl(conf))
 		ppl_write_stripe_run(conf);
 }
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 83911affcd88..f1b55495de53 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6427,7 +6427,7 @@ static int handle_active_stripes(struct r5conf *conf, int group,
 	release_inactive_stripe_list(conf, temp_inactive_list,
 				     NR_STRIPE_HASH_LOCKS);
 
-	r5l_flush_stripe_to_raid(conf->log);
+	r5l_flush_stripe_to_raid(conf);
 	if (release_inactive) {
 		spin_lock_irq(&conf->device_lock);
 		return 0;
@@ -6483,7 +6483,7 @@ static void raid5_do_work(struct work_struct *work)
 
 	flush_deferred_bios(conf);
 
-	r5l_flush_stripe_to_raid(conf->log);
+	r5l_flush_stripe_to_raid(conf);
 
 	async_tx_issue_pending_all();
 	blk_finish_plug(&plug);
@@ -6570,7 +6570,7 @@ static void raid5d(struct md_thread *thread)
 
 	flush_deferred_bios(conf);
 
-	r5l_flush_stripe_to_raid(conf->log);
+	r5l_flush_stripe_to_raid(conf);
 
 	async_tx_issue_pending_all();
 	blk_finish_plug(&plug);
-- 
2.30.2