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.
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
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
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