[PATCH 1/1] nvme-multipath: show wrong nvme ns after dlpar a nvme device

[wenxiong at linux.ibm.com]

From: Wen Xiong <wenxiong at linux.ibm.com>

If we have an active partition/namespace on nvme device, nvme device driver
won’t release these controller IDs/Namespaces IDs when dlpar remove.
So we got the wrong nvme devices names if nvme device driver still use old
subsystem id as controller id when dlpar add it back. We expect to see new
nvme devices with new controller IDs/Namespace IDs.

For example, we have a nvme U2 device with 4 namespaces in linux,

After system boots up,
Controller id:  0
Subsystem id:   0
namespaces ids: 1, 2, 3 and 4
nvme devices  : nvme0n1, nvme0n2, nvme0n3 and nvme0n4

Dlpar remove with active partitions on nvme0n1,
Controller id :   ID=0 still hold reference, ID=0 won’t be removed,  but /dev/nvme0 not exists anymore
Subsystem id :    0(nvme-subsys0 still exist in nvme list-subsys)
Namespace ids:    ID=1 still hold reference, ID=1 won’t be removed, but /dev/nvme0n1 not exists anymore
Nvme devices:  all nvme devices are gone in /dev

Dlpar Add back
Controller id:  1
Subsystem id :  0 still use old controller id=0
namespaces ids: 2, 3, 4 and 5
nvme devices:   We saw "nvme0n2, nvme0n3, nvme0n4, nvme0n5" in /dev
                /dev/nvme0 not exist anymore,
                We expect to see: nvme1n2, nvme1n3, nvme1n4 and nvme1n5

The patch fixes the issue.

Signed-off-by: Wen Xiong <wenxiong at linux.ibm.com>
---
 drivers/nvme/host/multipath.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index d464fdf978fb..945974ceef3c 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -495,7 +495,7 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
 	head->disk->fops = &nvme_ns_head_ops;
 	head->disk->private_data = head;
 	sprintf(head->disk->disk_name, "nvme%dn%d",
-			ctrl->subsys->instance, head->instance);
+			ctrl->instance, head->instance);
 
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, head->disk->queue);
 	blk_queue_flag_set(QUEUE_FLAG_NOWAIT, head->disk->queue);
-- 
2.31.1