fsid change of ZFS?

[Benjamin Kaduk]

On Sat, 20 Aug 2011, Rick Macklem wrote:

>> Yes, using vfs_getnewfsid() does not solve the issue.
>>
>> I noticed that Solaris looked up a fixed array vfssw[] exactly for
>> the purpose. I think a table like it is a good solution for fixing
>> fsid for each file system.
>>
>> -- Hiroki
> If anyone thinks using a fixed table to assign vfc_typenum for known
> file system types is a bad idea, please let us know.

Fixed table sounds like a good plan.
Is there a reason for/against using a hash table for types that are not in 
the fixed table?  The advantage would be that out-of-tree filesystems get 
a consistent typenum (modulo hash collisions), but there would be more 
overhead in maintaining the table.

-Ben Kaduk