On Mon, Jul 22, 2013 at 03:37:00PM -0400, Bryan Schumaker wrote: > On 07/22/2013 03:30 PM, J. Bruce Fields wrote: > > On Mon, Jul 22, 2013 at 03:17:29PM -0400, Bryan Schumaker wrote: > >> On 07/22/2013 02:50 PM, J. Bruce Fields wrote: > >>> On Fri, Jul 19, 2013 at 05:03:49PM -0400, bjschuma@xxxxxxxxxx wrote: > >>>> From: Bryan Schumaker <bjschuma@xxxxxxxxxx> > >>>> > >>>> Rather than performing the copy right away, schedule it to run later and > >>>> reply to the client. Later, send a callback to notify the client that > >>>> the copy has finished. > >>> > >>> I believe you need to implement the referring triple support described > >>> in http://tools.ietf.org/html/rfc5661#section-2.10.6.3 to fix the race > >>> described in > >>> http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion2-19#section-15.1.3 > >>> . > >> > >> I'll re-read and re-write. > >> > >>> > >>> I see cb_delay initialized below, but not otherwise used. Am I missing > >>> anything? > >> > >> Whoops! I was using that earlier to try to fake up a callback, but I eventually decided it's easier to just do the copy asynchronously. I must have forgotten to take it out :( > >> > >>> > >>> What about OFFLOAD_STATUS and OFFLOAD_ABORT? > >> > >> I haven't thought out those too much... I haven't thought about a use for them on the client yet. > > > > If it might be a long-running copy, I assume the client needs the > > ability to abort if the caller is killed. > > > > (Dumb question: what happens on the network partition? Does the server > > abort the copy when it expires the client state?) > > > > In any case, > > http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion2-19#section-15.1.3 > > says "If a server's COPY operation returns a stateid, then the server > > MUST also support these operations: CB_OFFLOAD, OFFLOAD_ABORT, and > > OFFLOAD_STATUS." > > > > So even if we've no use for them on the client then we still need to > > implement them (and probably just write a basic pynfs test). Either > > that or update the spec. > > Fair enough. I'll think it out and do something! Easy solution: save this patch for later and only support the sync version of copy for the final version of this patch series. I can't remember--does the spec give the server a clear way to bail out and tell the client to fall back on a normal copy in cases where the server knows the copy could take an unreasonable amount of time? --b. > > - Bryan > > > > >>> In some common cases the reply will be very quick, and we might be > >>> better off handling it synchronously. Could we implement a heuristic > >>> like "copy synchronously if the filesystem has special support or the > >>> range is less than the maximum iosize, otherwise copy asynchronously"? > >> > >> I'm sure that can be done, I'm just not sure how to do it yet... > > > > OK, thanks. > > > > --b. > > > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
