[Gluster-devel] libgfapi changes to add lk_owner and lease ID
Kaleb S. KEITHLEY
kkeithle at redhat.com
Fri Dec 4 12:54:06 UTC 2015
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?
> 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,
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