From: Hannes Reinecke <hare@suse.de>

When triggering a rescan due to a namespace resize we will be
receiving AENs on every controller, triggering a rescan of all
attached namespaces. If multipath is active only the current path and
the ns_head disk will be updated, the other paths will still refer to
the old size until AENs for the remaining controllers are received.

If I/O comes in before that it might be routed to one of the old
paths, triggering an I/O failure with 'access beyond end of device'.
With this patch the old paths are skipped from multipath path
selection until the controller serving these paths has been rescanned.

Signed-off-by: Hannes Reinecke <hare@suse.de>
[dwagner: - introduce NVME_NS_READY flag instead of NVME_NS_INVALIDATE
           - use 'revalidate' instead of 'invalidate' which
	    follows the zoned device code path.]
Tested-by: Daniel Wagner <redacted>
Signed-off-by: Daniel Wagner <redacted>
---
v3:
   - Renamed nvme_mpath_invalidated_paths to nvme_mpath_revalidate_paths()
   - Replaced NVME_NS_INVALIDATE with NVME_NS_READY
v2:
   - https://lore.kernel.org/linux-nvme/20210730071059.124347-1-dwagner@suse.de/ (local)
   - removed churn from failed rebase.
v1:
   - https://lore.kernel.org/linux-nvme/20210729194630.i5mhvvgb73duojqq@beryllium.lan/ (local)

drivers/nvme/host/core.c      |  3 +++
  drivers/nvme/host/multipath.c | 17 ++++++++++++++++-
  drivers/nvme/host/nvme.h      |  5 +++++
  3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 2f0cbaba12ac..54aafde4f556 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c

@@ -1878,6 +1878,7 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
  			goto out_unfreeze;
  	}
  
+	set_bit(NVME_NS_READY, &ns->flags);
  	blk_mq_unfreeze_queue(ns->disk->queue);
  
  	if (blk_queue_is_zoned(ns->queue)) {

@@ -1889,6 +1890,7 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
  	if (nvme_ns_head_multipath(ns->head)) {
  		blk_mq_freeze_queue(ns->head->disk->queue);
  		nvme_update_disk_info(ns->head->disk, ns, id);
+		nvme_mpath_revalidate_paths(ns);
  		blk_stack_limits(&ns->head->disk->queue->limits,
  				 &ns->queue->limits, 0);
  		blk_queue_update_readahead(ns->head->disk->queue);

@@ -3816,6 +3818,7 @@ static void nvme_ns_remove(struct nvme_ns *ns)
  	if (test_and_set_bit(NVME_NS_REMOVING, &ns->flags))
  		return;
  
+	clear_bit(NVME_NS_READY, &ns->flags);
  	set_capacity(ns->disk, 0);
  	nvme_fault_inject_fini(&ns->fault_inject);
  

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 3f32c5e86bfc..d390f14b8bb6 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c

@@ -147,6 +147,21 @@ void nvme_mpath_clear_ctrl_paths(struct nvme_ctrl *ctrl)
  	mutex_unlock(&ctrl->scan_lock);
  }
  
+void nvme_mpath_revalidate_paths(struct nvme_ns *ns)
+{
+	struct nvme_ns_head *head = ns->head;
+	sector_t capacity = get_capacity(head->disk);
+	int node;
+
+	for_each_node(node)
+		rcu_assign_pointer(head->current_path[node], NULL);
+
+	list_for_each_entry_rcu(ns, &head->list, siblings) {
+		if (capacity != get_capacity(ns->disk))
+			clear_bit(NVME_NS_READY, &ns->flags);
+	}