linux-kernel - [PATCH 5/5] md/raid5: Don't read ->active

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Date:   Thu, 11 Aug 2022 11:14:17 -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>,
        Guoqing Jiang <guoqing.jiang@...ux.dev>,
        Stephen Bates <sbates@...thlin.com>,
        Martin Oliveira <Martin.Oliveira@...eticom.com>,
        David Sloan <David.Sloan@...eticom.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH 5/5] md/raid5: Don't read ->active_stripes if it's not needed

The atomic_read() is not needed in many cases so only do
the read after the first checks are done.

Suggested-by: Christoph Hellwig <hch@...radead.org>
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 drivers/md/raid5.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 7e7205bb40f1..0b73eeea1b19 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -789,15 +789,14 @@ struct stripe_request_ctx {
  */
 static bool is_inactive_blocked(struct r5conf *conf, int hash)
 {
-	int active = atomic_read(&conf->active_stripes);
-
 	if (list_empty(conf->inactive_list + hash))
 		return false;
 
 	if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
 		return true;
 
-	return active < (conf->max_nr_stripes * 3 / 4);
+	return (atomic_read(&conf->active_stripes) <
+		(conf->max_nr_stripes * 3 / 4));
 }
 
 struct stripe_head *raid5_get_active_stripe(struct r5conf *conf,
-- 
2.30.2