Patch "nvme-multipath: prepare for "queue-depth" iopolicy" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    nvme-multipath: prepare for "queue-depth" iopolicy

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nvme-multipath-prepare-for-queue-depth-iopolicy.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c784734aef4944e365a1b84198bc61a201c8c242
Author: John Meneghini <jmeneghi@xxxxxxxxxx>
Date:   Tue Jun 25 08:26:04 2024 -0400

    nvme-multipath: prepare for "queue-depth" iopolicy
    
    [ Upstream commit 3d7c2fd2ea704812867f9586270a2516377482a3 ]
    
    This patch prepares for the introduction of a new iopolicy by breaking up
    the nvme_find_path() code path into sub-routines.
    
    Signed-off-by: John Meneghini <jmeneghi@xxxxxxxxxx>
    Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
    Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
    Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
    Stable-dep-of: 5dd18f09ce73 ("nvme/multipath: Fix RCU list traversal to use SRCU primitive")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index ede2a14dad8be..53eee6fc68392 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -290,10 +290,15 @@ static struct nvme_ns *nvme_next_ns(struct nvme_ns_head *head,
 	return list_first_or_null_rcu(&head->list, struct nvme_ns, siblings);
 }
 
-static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head,
-		int node, struct nvme_ns *old)
+static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head)
 {
 	struct nvme_ns *ns, *found = NULL;
+	int node = numa_node_id();
+	struct nvme_ns *old = srcu_dereference(head->current_path[node],
+					       &head->srcu);
+
+	if (unlikely(!old))
+		return __nvme_find_path(head, node);
 
 	if (list_is_singular(&head->list)) {
 		if (nvme_path_is_disabled(old))
@@ -339,7 +344,7 @@ static inline bool nvme_path_is_optimized(struct nvme_ns *ns)
 		ns->ana_state == NVME_ANA_OPTIMIZED;
 }
 
-inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
+static struct nvme_ns *nvme_numa_path(struct nvme_ns_head *head)
 {
 	int node = numa_node_id();
 	struct nvme_ns *ns;
@@ -347,14 +352,18 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
 	ns = srcu_dereference(head->current_path[node], &head->srcu);
 	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;
 }
 
+inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
+{
+	if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR)
+		return nvme_round_robin_path(head);
+	return nvme_numa_path(head);
+}
+
 static bool nvme_available_path(struct nvme_ns_head *head)
 {
 	struct nvme_ns *ns;