On 09/23/2011 08:17 PM, Sukwoo Kang wrote: > Hello, I'm trying to find out how NFSv4 client can get read > delegation. I'm using separate RHEL6 machines (2.6.32-71.el6.x86_64) > as server and client respectively. I'm able to get a read delegation by holding two files open at the same time. $ tail -f /nfs/file1.txt $ tail -f /nfs/file2.txt Will give me a read delegation in the second OPEN reply. - Bryan > > If I use pynfs, I can see server gives out read delegation. Basically > pynfs sends these RPCs to server - open (create), open_confirm, open, > open_confirm. > > On real NFS client, > > If I do 'cat <file>' twice, client does not get read delegation. > - (nfs4state.c) > - if (!cb_up || !sop->so_confirmed) > goto out; > - Here sop->so_confirmed is 0. > > If I open the existing file with O_RDONLY twice (i.e., open, not close > it and open again), client sends open only once to server. > - So here also sop->so_confirmed is 0. Delegation is not sent out. > (I've added more debug messages shown in below.) > > 2011-09-23T22:41:44.642938+02:00 int002st001 kernel: NFSD: > nfs4_open_delegation enter > 2011-09-23T22:41:44.642942+02:00 int002st001 kernel: NFSD: nfs4_open_claim_null > 2011-09-23T22:41:44.643853+02:00 int002st001 kernel: NFSD: cb_up=1, > sop->so_confirmed=0 > 2011-09-23T22:41:44.643857+02:00 int002st001 kernel: NFSD: either > callback is not up or not open confirmed > 2011-09-23T22:41:44.643858+02:00 int002st001 kernel: NFSD: > nfs4_open_delegation exit > > If I open the existing file with O_RDWR and then open it with > O_RDONLY, I can see "sop->so_confirmed = 1", but setlease failed. > - I think it is because there is writer on this file. > > 2011-09-23T11:23:28.116280+02:00 int002st001 kernel: NFSD: > nfs4_open_delegation enter > 2011-09-23T11:23:28.116717+02:00 int002st001 kernel: NFSD: nfs4_open_claim_null > 2011-09-23T11:23:28.117879+02:00 int002st001 kernel: NFSD: cb_up=1, > sop->so_confirmed=1 > 2011-09-23T11:23:28.117887+02:00 int002st001 kernel: NFSD alloc_init_deleg > 2011-09-23T11:23:28.117889+02:00 int002st001 kernel: NFSD: setlease > failed [-11], no delegation > 2011-09-23T11:23:28.119101+02:00 int002st001 kernel: NFSD: > close_delegation dp ffff88006ba05e60 > 2011-09-23T11:23:28.119109+02:00 int002st001 kernel: NFSD: freeing dp > ffff88006ba05e60 > 2011-09-23T11:23:28.120050+02:00 int002st001 kernel: NFSD: > nfs4_open_delegation exit > > What is missing here? I will appreciate any advice. Thank you. > > Regards, > Sukwoo Kang > -- > 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 -- 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
