[PATCH 1/2] nvme: propagate I/O errors during partition scan

[Hannes Reinecke]

Partition scan is triggered from device_add_disk(), and is needs to
terminate such the namespace scanning can continue.
This patch adds two new flags NVME_NSHEAD_DISK_SCAN to signal that
the 'head' device is currently in partition scan, and NVME_NS_SCAN_FAILED
to signal that I/O errors had been encountered on the namespace during
partition scan.
With these flags we can modify the failover mechanism to count any namespace
with NVME_NS_SCAN_FAILED as a disabled path, and to not queue commands when
all paths are disabled and NVME_NSHEAD_DISK_SCAN is set.

Signed-off-by: Hannes Reinecke <hare at kernel.org>
---
 drivers/nvme/host/core.c      | 26 ++++++++++++++++++++------
 drivers/nvme/host/multipath.c | 18 ++++++++++++++++++
 drivers/nvme/host/nvme.h      |  2 ++
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 651073280f6f..d8581ddd9a2e 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4007,8 +4007,10 @@ static void nvme_validate_ns(struct nvme_ns *ns, struct nvme_ns_info *info)
 	 *
 	 * TODO: we should probably schedule a delayed retry here.
 	 */
-	if (ret > 0 && (ret & NVME_STATUS_DNR))
+	if (ret > 0 && (ret & NVME_STATUS_DNR)) {
+		set_bit(NVME_NS_SCAN_FAILED, &ns->flags);
 		nvme_ns_remove(ns);
+	}
 }
 
 static void nvme_scan_ns(struct nvme_ctrl *ctrl, unsigned nsid)
@@ -4017,8 +4019,14 @@ static void nvme_scan_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 	struct nvme_ns *ns;
 	int ret;
 
-	if (nvme_identify_ns_descs(ctrl, &info))
+	ns = nvme_find_get_ns(ctrl, nsid);
+	if (nvme_identify_ns_descs(ctrl, &info)) {
+		if (ns) {
+			set_bit(NVME_NS_SCAN_FAILED, &ns->flags);
+			nvme_put_ns(ns);
+		}
 		return;
+	}
 
 	if (info.ids.csi != NVME_CSI_NVM && !nvme_multi_css(ctrl)) {
 		dev_warn(ctrl->device,
@@ -4037,17 +4045,23 @@ static void nvme_scan_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 	else
 		ret = nvme_ns_info_from_identify(ctrl, &info);
 
-	if (info.is_removed)
-		nvme_ns_remove_by_nsid(ctrl, nsid);
+	if (info.is_removed && ns) {
+		nvme_ns_remove(ns);
+		nvme_put_ns(ns);
+	}
 
 	/*
 	 * Ignore the namespace if it is not ready. We will get an AEN once it
 	 * becomes ready and restart the scan.
 	 */
-	if (ret || !info.is_ready)
+	if (ret || !info.is_ready) {
+		if (ret > 0 && ns) {
+			set_bit(NVME_NS_SCAN_FAILED, &ns->flags);
+			nvme_put_ns(ns);
+		}
 		return;
+	}
 
-	ns = nvme_find_get_ns(ctrl, nsid);
 	if (ns) {
 		nvme_validate_ns(ns, &info);
 		nvme_put_ns(ns);
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index f72c5a6a2d8e..68eb1df98419 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -92,6 +92,13 @@ void nvme_failover_req(struct request *req)
 
 	nvme_mpath_clear_current_path(ns);
 
+	/*
+	 * Mark the namespace with NS_SCAN_FAILED to ensure
+	 * I/O can be aborted during partition scan.
+	 */
+	if (test_bit(NVME_NSHEAD_DISK_SCAN, &ns->head->flags))
+		set_bit(NVME_NS_SCAN_FAILED, &ns->flags);
+
 	/*
 	 * If we got back an ANA error, we know the controller is alive but not
 	 * ready to serve this namespace.  Kick of a re-read of the ANA
@@ -227,6 +234,7 @@ void nvme_mpath_revalidate_paths(struct nvme_ns *ns)
 	list_for_each_entry_rcu(ns, &head->list, siblings) {
 		if (capacity != get_capacity(ns->disk))
 			clear_bit(NVME_NS_READY, &ns->flags);
+		clear_bit(NVME_NS_SCAN_FAILED, &ns->flags);
 	}
 	srcu_read_unlock(&head->srcu, srcu_idx);
 
@@ -239,6 +247,12 @@ static bool nvme_path_is_disabled(struct nvme_ns *ns)
 {
 	enum nvme_ctrl_state state = nvme_ctrl_state(ns->ctrl);
 
+	if (test_bit(NVME_NSHEAD_DISK_SCAN, &ns->head->flags)) {
+		if (state == NVME_CTRL_DELETING ||
+		    test_bit(NVME_NS_SCAN_FAILED, &ns->flags))
+			return true;
+	}
+
 	/*
 	 * We don't treat NVME_CTRL_DELETING as a disabled path as I/O should
 	 * still be able to complete assuming that the controller is connected.
@@ -423,6 +437,8 @@ static bool nvme_available_path(struct nvme_ns_head *head)
 
 	if (!test_bit(NVME_NSHEAD_DISK_LIVE, &head->flags))
 		return NULL;
+	if (test_bit(NVME_NSHEAD_DISK_SCAN, &head->flags))
+		return NULL;
 
 	list_for_each_entry_rcu(ns, &head->list, siblings) {
 		if (test_bit(NVME_CTRL_FAILFAST_EXPIRED, &ns->ctrl->flags))
@@ -646,8 +662,10 @@ static void nvme_mpath_set_live(struct nvme_ns *ns)
 	 * head.
 	 */
 	if (!test_and_set_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) {
+		set_bit(NVME_NSHEAD_DISK_SCAN, &head->flags);
 		rc = device_add_disk(&head->subsys->dev, head->disk,
 				     nvme_ns_attr_groups);
+		clear_bit(NVME_NSHEAD_DISK_SCAN, &head->flags);
 		if (rc) {
 			clear_bit(NVME_NSHEAD_DISK_LIVE, &head->flags);
 			return;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 50515ad0f9d6..6089528d5eb8 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -493,6 +493,7 @@ struct nvme_ns_head {
 	struct mutex		lock;
 	unsigned long		flags;
 #define NVME_NSHEAD_DISK_LIVE	0
+#define NVME_NSHEAD_DISK_SCAN	1
 	struct nvme_ns __rcu	*current_path[];
 #endif
 };
@@ -527,6 +528,7 @@ struct nvme_ns {
 #define NVME_NS_ANA_PENDING	2
 #define NVME_NS_FORCE_RO	3
 #define NVME_NS_READY		4
+#define NVME_NS_SCAN_FAILED	5
 
 	struct cdev		cdev;
 	struct device		cdev_device;
-- 
2.35.3