Messages in this thread | | | Date | Thu, 15 Sep 2016 05:36:46 -0700 | From | Christoph Hellwig <> | Subject | Re: [Nbd] [RESEND][PATCH 0/5] nbd improvements |
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On Thu, Sep 15, 2016 at 01:33:20PM +0100, Alex Bligh wrote: > At an implementation level that is going to be a little difficult > for some NBD servers, e.g. ones that fork() a different process per > connection. There is in general no IPC to speak of between server > instances. Such servers would thus be unsafe with more than one > connection if FLUSH is in use. > > I believe such servers include the reference server where there is > process per connection (albeit possibly with several threads). > > Even single process servers (including mine - gonbdserver) would > require logic to pair up multiple connections to the same > device.
Why? If you only send the completion after your I/O syscall returned your are fine if fsync comes from a difference process, no matter if you're using direct or buffered I/O underneath.
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