[PATCH 3/3] nvme: freeze both the ns and multipath queues whe updating queue limits

[Christoph Hellwig]

We really should not have any I/O outstanding while updating the queue
limits, as that could introduce inconsistencies between the multipath
and underlying nodes.  So always freeze the multipath node first and then
the underlying one, matching the order in nvme_passthru_start.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/nvme/host/core.c | 41 ++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 81d2a09dd00f30..0f01a0bf976fd3 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2095,6 +2095,24 @@ static void nvme_set_chunk_sectors(struct nvme_ns *ns, struct nvme_id_ns *id,
 	lim->chunk_sectors = iob;
 }
 
+/*
+ * Freeze all I/O for a namespace, including clearing out anything on the
+ * multipath node.
+ */
+static void nvme_ns_freeze(struct nvme_ns *ns)
+{
+	if (nvme_ns_head_multipath(ns->head))
+		blk_mq_freeze_queue(ns->head->disk->queue);
+	blk_mq_freeze_queue(ns->disk->queue);
+}
+
+static void nvme_ns_unfreeze(struct nvme_ns *ns)
+{
+	blk_mq_unfreeze_queue(ns->disk->queue);
+	if (nvme_ns_head_multipath(ns->head))
+		blk_mq_unfreeze_queue(ns->head->disk->queue);
+}
+
 /*
  * The queue_limits structure mixes values that are the hardware limitations for
  * bio splitting with what is the device configuration.
@@ -2116,7 +2134,8 @@ static int nvme_update_ns_info_mpath(struct nvme_ns *ns,
 	struct queue_limits lim;
 	int ret;
 
-	blk_mq_freeze_queue(disk->queue);
+	WARN_ON_ONCE(disk->queue->mq_freeze_depth < 1);
+
 	lim = queue_limits_start_update(disk->queue);
 	lim.logical_block_size = ns_lim->logical_block_size;
 	lim.physical_block_size = ns_lim->physical_block_size;
@@ -2132,7 +2151,6 @@ static int nvme_update_ns_info_mpath(struct nvme_ns *ns,
 	set_capacity_and_notify(disk, get_capacity(ns->disk));
 	set_disk_ro(disk, nvme_ns_is_readonly(ns, info));
 	nvme_mpath_revalidate_paths(ns);
-	blk_mq_unfreeze_queue(disk->queue);
 
 	return ret;
 }
@@ -2143,7 +2161,7 @@ static int nvme_update_ns_info_generic(struct nvme_ns *ns,
 	struct queue_limits lim;
 	int ret;
 
-	blk_mq_freeze_queue(ns->disk->queue);
+	nvme_ns_freeze(ns);
 	lim = queue_limits_start_update(ns->disk->queue);
 	nvme_set_ctrl_limits(ns->ctrl, &lim);
 	ret = queue_limits_commit_update(ns->disk->queue, &lim);
@@ -2154,11 +2172,11 @@ static int nvme_update_ns_info_generic(struct nvme_ns *ns,
 	ns->disk->flags |= GENHD_FL_HIDDEN;
 	set_bit(NVME_NS_READY, &ns->flags);
 	set_disk_ro(ns->disk, nvme_ns_is_readonly(ns, info));
+	if (nvme_ns_head_multipath(ns->head))
+		ret = nvme_update_ns_info_mpath(ns, info, true);
 
 out_unfreeze:
-	blk_mq_unfreeze_queue(ns->disk->queue);
-	if (nvme_ns_head_multipath(ns->head) && !ret)
-		ret = nvme_update_ns_info_mpath(ns, info, true);
+	nvme_ns_unfreeze(ns);
 	return ret;
 }
 
@@ -2204,7 +2222,7 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
 			goto out;
 	}
 
-	blk_mq_freeze_queue(ns->disk->queue);
+	nvme_ns_freeze(ns);
 	ns->head->lba_shift = id->lbaf[lbaf].ds;
 	ns->head->nuse = le64_to_cpu(id->nuse);
 	capacity = nvme_lba_to_sect(ns->head, le64_to_cpu(id->nsze));
@@ -2236,7 +2254,7 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
 
 	ret = queue_limits_commit_update(ns->disk->queue, &lim);
 	if (ret) {
-		blk_mq_unfreeze_queue(ns->disk->queue);
+		nvme_ns_unfreeze(ns);
 		goto out;
 	}
 
@@ -2254,7 +2272,9 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
 done:
 	set_disk_ro(ns->disk, nvme_ns_is_readonly(ns, info));
 	set_bit(NVME_NS_READY, &ns->flags);
-	blk_mq_unfreeze_queue(ns->disk->queue);
+	if (nvme_ns_head_multipath(ns->head))
+		ret = nvme_update_ns_info_mpath(ns, info, unsupported);
+	nvme_ns_unfreeze(ns);
 
 	if (blk_queue_is_zoned(ns->queue)) {
 		ret = blk_revalidate_disk_zones(ns->disk);
@@ -2266,9 +2286,6 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
 out:
 	kfree(nvm);
 	kfree(id);
-
-	if (nvme_ns_head_multipath(ns->head) && !ret)
-		ret = nvme_update_ns_info_mpath(ns, info, unsupported);
 	return ret;
 }
 
-- 
2.43.0