[Virtio-fs] Ways to uniquely and persistently identify nodes

[Max Reitz]

On 15.01.20 10:37, Max Reitz wrote:

[...]

>>> I just had a very fuzzy (and maybe stupid) idea: Maybe we could keep an
>>> internal vector of currently active handles and then when variable-size
>>> handles are enabled, fuse_ino_t would just act as an index into that vector?
>>>
>>> I suppose we could then use the full-size handles in all messages and
>>> just hand out temporary indices to existing functions (just so we don’t
>>> have to change their interface).  Server and client have their own
>>> vectors, because when they communicate, only the full handles have meaning.
>>>
>>> Or we could implement the table on top of the current system by sharing
>>> it between the client and server.  Whenever the server creates a
>>> fuse_ino_t value, it then also creates a full-size handle, and returns
>>> both the handle and its corresponding fuse_ino_t value to the server.
>>> The server can use the fuse_ino_t normally most of the time, but with a
>>> catch: The client would be able to invalidate it.  Then the server needs
>>> to obtain a new fuse_ino_t value for the existing handle.
>>> (Invalidating and reacquiring a fuse_ino_t value would be new FUSE
>>> operations.)
>>
>> I think you may have accidentally switched "server" and "client" in
>> the above description a couple of times.
> 
> Isn’t the kernel (i.e., the guest) the client and virtiofsd the server?

Oh, er, yes.  So I started to get it wrong after “returns both the
handle...”.  Sorry. O:-)

Max

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