Thread (40 messages) 40 messages, 1 author, 2020-08-08
STALE2172d REVIEWED: 4 (4M)

[PATCH AUTOSEL 5.4 40/40] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths

From: Sasha Levin <sashal@kernel.org>
Date: 2020-08-08 23:43:37
Also in: linux-nvme, lkml
Subsystem: nvm express driver, the rest · Maintainers: Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg, Linus Torvalds

From: Hannes Reinecke <hare@suse.de>

[ Upstream commit fbd6a42d8932e172921c7de10468a2e12c34846b ]

When nvme_round_robin_path() finds a valid namespace we should be using it;
falling back to __nvme_find_path() for non-optimized paths will cause the
result from nvme_round_robin_path() to be ignored for non-optimized paths.

Fixes: 75c10e732724 ("nvme-multipath: round-robin I/O policy")
Signed-off-by: Martin Wilck <redacted>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/nvme/host/multipath.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 38d25d7c6bca3..484aad0d0c9c6 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -275,10 +275,13 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
 	struct nvme_ns *ns;
 
 	ns = srcu_dereference(head->current_path[node], &head->srcu);
-	if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
-		ns = nvme_round_robin_path(head, node, ns);
-	if (unlikely(!ns || !nvme_path_is_optimized(ns)))
-		ns = __nvme_find_path(head, node);
+	if (unlikely(!ns))
+		return __nvme_find_path(head, node);
+
+	if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR)
+		return nvme_round_robin_path(head, node, ns);
+	if (unlikely(!nvme_path_is_optimized(ns)))
+		return __nvme_find_path(head, node);
 	return ns;
 }
 
-- 
2.25.1
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