linux-kernel - [PATCH v2 03/17] md/raid5-cache: Refactor r5l

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Date:   Thu, 26 May 2022 10:35:50 -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 03/17] md/raid5-cache: Refactor r5l_start() to take a struct r5conf

All calls to r5l_start() 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_start() 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 | 9 +++------
 drivers/md/raid5-log.h   | 2 +-
 drivers/md/raid5.c       | 4 ++--
 3 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 96f51ce9b6c1..7c5dc45b1ea8 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -3034,20 +3034,17 @@ static int r5l_load_log(struct r5l_log *log)
 	return ret;
 }
 
-int r5l_start(struct r5l_log *log)
+int r5l_start(struct r5conf *conf)
 {
+	struct r5l_log *log = conf->log;
 	int ret;
 
 	if (!log)
 		return 0;
 
 	ret = r5l_load_log(log);
-	if (ret) {
-		struct mddev *mddev = log->rdev->mddev;
-		struct r5conf *conf = mddev->private;
-
+	if (ret)
 		r5l_exit_log(conf);
-	}
 	return ret;
 }
 
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index 720e164e4d4d..db4c1262b380 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -29,7 +29,7 @@ void r5c_check_cached_full_stripe(struct r5conf *conf);
 extern struct md_sysfs_entry r5c_journal_mode;
 void r5c_update_on_rdev_error(struct mddev *mddev, struct md_rdev *rdev);
 bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
-int r5l_start(struct r5l_log *log);
+int r5l_start(struct r5conf *conf);
 
 struct dma_async_tx_descriptor *
 ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 458d88faf2e9..83911affcd88 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8040,7 +8040,7 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 		if (ret)
 			return ret;
 
-		ret = r5l_start(conf->log);
+		ret = r5l_start(conf);
 		if (ret)
 			return ret;
 
@@ -8743,7 +8743,7 @@ static int raid5_start(struct mddev *mddev)
 {
 	struct r5conf *conf = mddev->private;
 
-	return r5l_start(conf->log);
+	return r5l_start(conf);
 }
 
 static struct md_personality raid6_personality =
-- 
2.30.2