nvme/pcie hot plug results in /dev name change

[John Meneghini]

We have a customer complaining that when they hot unplug/plug their nvme-pci device the device name changes.

For example, when they hot remove /dev/nvme1n1 physically, then reinsert it, it gets identified as /dev/nvme4n1.

IIRC there is nothing about nvme_init_ctrl that guarantees the ctrl->instance will be the same because
ida_alloc() will only return the next free id in the bitmap.

The fact that nvme_remove ->  nvme_init_ctrl many times results in the same ctrl->instance is just a happen stance and there is 
nothing that guarantees /dev name consistency in Linux. Especially in the case of hot unplug/plug where the controller may very 
well be marked NVME_CTRL_DEAD due to the ungraceful disconnect.

True?

-- 
John A. Meneghini
Senior Principal Platform Storage Engineer
RHEL SST - Platform Storage Group
jmeneghi at redhat.com