[PATCH] nvme-core: decode the error on add disk()

[PATCH] nvme-core: decode the error on add disk()

[Chaitanya Kulkarni]

While debugging the problem, it is important to know that what exact
error returned by device_add_disk() along side the disk name. Print
the error along with disk name when device_add_disk() fails when
allocating the namespace.

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
---
 drivers/nvme/host/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 2a0555856795..0be42f9b86b5 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3868,6 +3868,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
 	struct nvme_ns *ns;
 	struct gendisk *disk;
 	int node = ctrl->numa_node;
+	int rc;
 
 	ns = kzalloc_node(sizeof(*ns), GFP_KERNEL, node);
 	if (!ns)
@@ -3933,8 +3934,12 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
 	synchronize_srcu(&ctrl->srcu);
 	nvme_get_ctrl(ctrl);
 
-	if (device_add_disk(ctrl->device, ns->disk, nvme_ns_attr_groups))
+	rc = device_add_disk(ctrl->device, ns->disk, nvme_ns_attr_groups);
+	if (rc) {
+		dev_err(ctrl->device, "%s:failed to add disk %d:%s\n",
+			__func__, rc, disk->disk_name);
 		goto out_cleanup_ns_from_list;
+	}
 
 	if (!nvme_ns_head_multipath(ns->head))
 		nvme_add_ns_cdev(ns);
-- 
2.40.0

Re: [PATCH] nvme-core: decode the error on add disk()

[Christoph Hellwig]

On Thu, Jan 16, 2025 at 12:15:27PM -0800, Chaitanya Kulkarni wrote:
> While debugging the problem, it is important to know that what exact
> error returned by device_add_disk() along side the disk name. Print
> the error along with disk name when device_add_disk() fails when
> allocating the namespace.

Sounds like this would be better places in device_add_disk and not
in the drivers.

Re: [PATCH] nvme-core: decode the error on add disk()

[Ewan Milne]

On Thu, Jan 16, 2025 at 3:19 PM Chaitanya Kulkarni <kch@nvidia.com> wrote:
>
> While debugging the problem, it is important to know that what exact
> error returned by device_add_disk() along side the disk name. Print
> the error along with disk name when device_add_disk() fails when
> allocating the namespace.

This is fine as far as it goes.  Looking at the code around namespace scanning
there appear to be several other places where an error is silently handled and
the namespace won't show up.  e.g. if nvme_get_effects_log() -> nvme_get_log()
fails in nvme_alloc_ns_head().  That is beyond the intent of this one
patch though.

Reviewed-by: Ewan D. Milne <emilne@redhat.com>