[PATCH v2 3/7] nvme-multipath: queue-depth support for marginal paths

[Jesse Taube]

From: John Meneghini <jmeneghi at redhat.com>

Exclude marginal paths from queue-depth io policy. In the case where all
paths are marginal and no optimized or non-optimized path is found, we
fall back and select the best marginal path.

Signed-off-by: Jesse Taube <jtaubepe at redhat.com>
Signed-off-by: John Meneghini <jmeneghi at redhat.com>
---
V10 -> V1:
 - New commit
V1 -> V2:
 - Rewrite
---
 drivers/nvme/host/multipath.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index dbf09cdda815..f28797deab68 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -439,12 +439,17 @@ static struct nvme_ns *nvme_queue_depth_path(struct nvme_ns_head *head)
 	struct nvme_ns *best_opt = NULL, *best_nonopt = NULL, *ns;
 	unsigned int min_depth_opt = UINT_MAX, min_depth_nonopt = UINT_MAX;
 	unsigned int depth;
+	bool need_marginal = nvme_all_paths_marginal(head);
 
 	list_for_each_entry_srcu(ns, &head->list, siblings,
 				 srcu_read_lock_held(&head->srcu)) {
 		if (nvme_path_is_disabled(ns))
 			continue;
 
+		/* Skip marginal paths unless we need to use them */
+		if (!need_marginal && nvme_ctrl_is_marginal(ns->ctrl))
+			continue;
+
 		depth = atomic_read(&ns->ctrl->nr_active);
 
 		switch (ns->ana_state) {
-- 
2.55.0