[PATCH 1/3] nvme: introduce nvme_ctrl_is_mpath helper

[Sagi Grimberg]

Given that our error recovery and I/O failover logic semantics is
different for multipath vs. non-multipath controllers, transports
need a helper to distinguish how to react upon error recovery
or controller resets (i.e. fail I/O or to keep the queue
frozen/quiesced).

Fixes: 9f98772ba307 ("nvme-rdma: fix controller reset hang during traffic")
Fixes: 2875b0aecabe ("nvme-tcp: fix controller reset hang during traffic")
[sagi: added the fixes tag so this can also go to stable with its respective
fixes]
Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
---
 drivers/nvme/host/multipath.c |  5 +++--
 drivers/nvme/host/nvme.h      | 15 +++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index a1d476e1ac02..5c67a5e96738 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -8,10 +8,11 @@
 #include <trace/events/block.h>
 #include "nvme.h"
 
-static bool multipath = true;
+bool multipath = true;
 module_param(multipath, bool, 0444);
 MODULE_PARM_DESC(multipath,
 	"turn on native support for multiple controllers per subsystem");
+EXPORT_SYMBOL_GPL(multipath);
 
 void nvme_mpath_unfreeze(struct nvme_subsystem *subsys)
 {
@@ -372,7 +373,7 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
 	 * We also do this for private namespaces as the namespace sharing data could
 	 * change after a rescan.
 	 */
-	if (!(ctrl->subsys->cmic & NVME_CTRL_CMIC_MULTI_CTRL) || !multipath)
+	if (!nvme_ctrl_is_mpath(ctrl))
 		return 0;
 
 	q = blk_alloc_queue(ctrl->numa_node);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 07b34175c6ce..4f7c9970e3fc 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -840,4 +840,19 @@ struct nvme_ctrl *nvme_ctrl_from_file(struct file *file);
 struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid);
 void nvme_put_ns(struct nvme_ns *ns);
 
+extern bool multipath;
+#ifdef CONFIG_NVME_MULTIPATH
+static inline bool nvme_ctrl_is_mpath(struct nvme_ctrl *ctrl)
+{
+	return !(!(ctrl->subsys->cmic & NVME_CTRL_CMIC_MULTI_CTRL) || !multipath);
+
+}
+#else
+static inline bool nvme_ctrl_is_mpath(struct nvme_ctrl *ctrl)
+{
+	return false;
+
+}
+#endif
+
 #endif /* _NVME_H */
-- 
2.27.0