[Gluster-devel] libgfapi changes to add lk_owner and lease ID

[Kaleb S. KEITHLEY]

On 12/04/2015 07:51 AM, Ira Cooper wrote:
>
>>>>
>>>> why not use storage in the client_t instead of thread local?
>>>
>>> It comes down to the use case.  For Samba, the right spot is almost
>>> certainly the fd, because lease keys are a per-handle (which we map to
>>> fd) property.
>>>
>>> client_t is a horror show, due to race conditions between threads, IMHO.
>>
>> If there are known races, should we not address that? Got a bug that
>> explains it in more detail?
> 
> Niels,
> 
> For samba, if we do multi-threaded open, Kaleb's proposal is a
> race-condition.  I haven't gone through every use of client_t and seen
> if it is racy.
> 
> The race here is pretty simple:
> 
> Thread 1: Sets lease_id
> Thread 2: Sets lease_id
> Thread 1: Opens file. (wrong lease_id)
> 
> If these two threads represent requests from different clients, client_t
> won't work, unless there's a client_t per-thread.

client_t is, as one might guess from the name, per client (connection).
If smbd has a single connection, then there's a single client_t for it.

> 
> For global things on the connection, client_t is fine, and appropriate.
> For this?  No.
> 
> This is a property per-open, and belongs in the glfs_fd and glfs_object,
> IMHO.
> 
> Thanks,
> 
> -Ira
> 

-- 

Kaleb