The multipath code currently deletes the disk only after all references
to it are dropped rather than when the last path to that disk is lost.
This has been reported to cause problems with some use cases like MD RAID.

What is the exact problem?

Can you describe what the problem you see now and what you expect
to see (unrelated to patch #1)?

This patch implements an alternative behaviour of deleting the disk when
the last path is gone, ie the same behaviour as non-multipathed nvme
devices.

But we also don't remove the non-multipath'd nvme device until the
last reference drops (e.g. if you have a mounted filesystem on top).

This would be the equivalent to running raid on top of dm-mpath on
top of scsi devices right? And if all the mpath device nodes go away
the mpath device is deleted even if it has an open reference to it?

The new behaviour will be selected with the 'fail_if_no_path'
attribute, as returning it's arguably the same functionality.

But its not the same functionality.

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