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. - 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
