Re: [PATCH] nvme-multipath: fix multipath path scan

[Christoph Hellwig <hch@lst.de>]

On Wed, Feb 16, 2022 at 01:57:31PM +0100, Daniel Wagner wrote:
> > In nvme_update_zone_info, but nvme_configure_metadata is also possible.
> > Moved setting the flag before both these.
> 
> But the NS is not ready at this point. nvme_update_disk_info() needs run
> before the NS can be marked as ready. Commit message e7d65803e2bb
> ("nvme-multipath: revalidate paths during rescan") explains why.

Yeah.  So the only error return from nvme_configure_metadata is a can not
happen case which doesn't really need the error return.  So we only
need to check nvme_update_zone_info and can set the ns life for the
-ENODEV case there.  Something like the patch below:


diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 79005ea1a33e3..7814df10b5199 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1723,7 +1723,7 @@ static int nvme_setup_streams_ns(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 	return 0;
 }
 
-static int nvme_configure_metadata(struct nvme_ns *ns, struct nvme_id_ns *id)
+static void nvme_configure_metadata(struct nvme_ns *ns, struct nvme_id_ns *id)
 {
 	struct nvme_ctrl *ctrl = ns->ctrl;
 
@@ -1739,7 +1739,8 @@ static int nvme_configure_metadata(struct nvme_ns *ns, struct nvme_id_ns *id)
 
 	ns->features &= ~(NVME_NS_METADATA_SUPPORTED | NVME_NS_EXT_LBAS);
 	if (!ns->ms || !(ctrl->ops->flags & NVME_F_METADATA_SUPPORTED))
-		return 0;
+		return;
+
 	if (ctrl->ops->flags & NVME_F_FABRICS) {
 		/*
 		 * The NVMe over Fabrics specification only supports metadata as
@@ -1747,7 +1748,7 @@ static int nvme_configure_metadata(struct nvme_ns *ns, struct nvme_id_ns *id)
 		 * remap the separate metadata buffer from the block layer.
 		 */
 		if (WARN_ON_ONCE(!(id->flbas & NVME_NS_FLBAS_META_EXT)))
-			return -EINVAL;
+			return;
 
 		ns->features |= NVME_NS_EXT_LBAS;
 
@@ -1774,8 +1775,6 @@ static int nvme_configure_metadata(struct nvme_ns *ns, struct nvme_id_ns *id)
 		else
 			ns->features |= NVME_NS_METADATA_SUPPORTED;
 	}
-
-	return 0;
 }
 
 static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
@@ -1916,9 +1915,7 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
 	ns->lba_shift = id->lbaf[lbaf].ds;
 	nvme_set_queue_limits(ns->ctrl, ns->queue);
 
-	ret = nvme_configure_metadata(ns, id);
-	if (ret)
-		goto out_unfreeze;
+	nvme_configure_metadata(ns, id);
 	nvme_set_chunk_sectors(ns, id);
 	nvme_update_disk_info(ns->disk, ns, id);
 
@@ -1934,7 +1931,7 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
 	if (blk_queue_is_zoned(ns->queue)) {
 		ret = nvme_revalidate_zones(ns);
 		if (ret && !nvme_first_scan(ns->disk))
-			goto out;
+			return ret;
 	}
 
 	if (nvme_ns_head_multipath(ns->head)) {
@@ -1949,16 +1946,16 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
 	return 0;
 
 out_unfreeze:
-	blk_mq_unfreeze_queue(ns->disk->queue);
-out:
 	/*
 	 * If probing fails due an unsupported feature, hide the block device,
 	 * but still allow other access.
 	 */
 	if (ret == -ENODEV) {
 		ns->disk->flags |= GENHD_FL_HIDDEN;
+		set_bit(NVME_NS_READY, &ns->flags);
 		ret = 0;
 	}
+	blk_mq_unfreeze_queue(ns->disk->queue);
 	return ret;
 }