linux-kernel - [PATCH 2/5] md/raid5: Make is_inactive

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Message-Id: <20220727210600.120221-3-logang@deltatee.com>
Date:   Wed, 27 Jul 2022 15:05:57 -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 2/5] md/raid5: Make is_inactive_blocked() helper

The logic to wait_for_stripe is difficult to parse being on so many
lines and with confusing operator precedence. Move it to a helper
function to make it easier to read.

No functional changes intended.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 drivers/md/raid5.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index b1cb0be8fa67..e7e02a979670 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -755,6 +755,24 @@ static bool has_failed(struct r5conf *conf)
 	return degraded > conf->max_degraded;
 }
 
+/*
+ * Block until another thread clears R5_INACTIVE_BLOCKED or
+ * there are fewer than 3/4 the maximum number of active stripes
+ * and there is an inactive stripe available.
+ */
+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);
+}
+
 struct stripe_head *
 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
 			int previous, int noblock, int noquiesce)
@@ -796,11 +814,7 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
 	set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
 	r5l_wake_reclaim(conf->log, 0);
 	wait_event_lock_irq(conf->wait_for_stripe,
-			    !list_empty(conf->inactive_list + hash) &&
-			    (atomic_read(&conf->active_stripes)
-				  < (conf->max_nr_stripes * 3 / 4)
-				 || !test_bit(R5_INACTIVE_BLOCKED,
-					      &conf->cache_state)),
+			    is_inactive_blocked(conf, hash),
 			    *(conf->hash_locks + hash));
 	clear_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
 	goto retry;
-- 
2.30.2