> On May 18, 2023, at 1:11 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
>
>
> On 5/18/23 6:23 AM, Chuck Lever III wrote:
>>
>>> On May 17, 2023, at 7:38 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
>>>
>>> This patch grants write delegation for OPEN with NFS4_SHARE_ACCESS_WRITE
>>> if there is no conflict with other OPENs.
>>>
>>> Write delegation conflict with another OPEN, REMOVE, RENAME and SETATTR
>>> are handled the same as read delegation using notify_change,
>>> try_break_deleg.
>> Very clean. A couple of suggestions, one is down below, and here is
>> the other:
>>
>> I was thinking we should add one or two counters in fs/nfsd/stats.c
>> to track how often read and write delegations are offered, and
>> perhaps one to count the number of DELEGRETURN operations. What do
>> you think makes sense?
>
> I'm not sure what these counters will tell us, currently we already
> has a counter for number of delegations handed out.
I haven't found that, where is it? Certainly, if NFSD already
has one, then no need to add more.
It would be nice one day, perhaps, to have a metric of how many
delegations a client holds. That's not for this series.
> I think a counter
> on how often nfsd has to recall the write delegation due to GETATTR can
> be useful to know whether we should implement CB_GETATTR.
I hesitated to mention that because I wonder if that's something
that would be interesting only for defending a design choice,
not for site-to-site tuning. In other words, after we plumb it
into NFSD, it will never actually be used after CB_GETATTR
support is added.
Do you believe it's something that administrators can use to
help balance or tune their workloads?
>>> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
>>> ---
>>> fs/nfsd/nfs4state.c | 24 ++++++++++++++++--------
>>> 1 file changed, 16 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>> index 6e61fa3acaf1..09a9e16407f9 100644
>>> --- a/fs/nfsd/nfs4state.c
>>> +++ b/fs/nfsd/nfs4state.c
>>> @@ -1144,7 +1144,7 @@ static void block_delegations(struct knfsd_fh *fh)
>>>
>>> static struct nfs4_delegation *
>>> alloc_init_deleg(struct nfs4_client *clp, struct nfs4_file *fp,
>>> - struct nfs4_clnt_odstate *odstate)
>>> + struct nfs4_clnt_odstate *odstate, u32 dl_type)
>>> {
>>> struct nfs4_delegation *dp;
>>> long n;
>>> @@ -1170,7 +1170,7 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_file *fp,
>>> INIT_LIST_HEAD(&dp->dl_recall_lru);
>>> dp->dl_clnt_odstate = odstate;
>>> get_clnt_odstate(odstate);
>>> - dp->dl_type = NFS4_OPEN_DELEGATE_READ;
>>> + dp->dl_type = dl_type;
>>> dp->dl_retries = 1;
>>> dp->dl_recalled = false;
>>> nfsd4_init_cb(&dp->dl_recall, dp->dl_stid.sc_client,
>>> @@ -5451,6 +5451,7 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>> struct nfs4_delegation *dp;
>>> struct nfsd_file *nf;
>>> struct file_lock *fl;
>>> + u32 deleg;
>>>
>>> /*
>>> * The fi_had_conflict and nfs_get_existing_delegation checks
>>> @@ -5460,7 +5461,13 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>> if (fp->fi_had_conflict)
>>> return ERR_PTR(-EAGAIN);
>>>
>>> - nf = find_readable_file(fp);
>>> + if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) {
>>> + nf = find_writeable_file(fp);
>>> + deleg = NFS4_OPEN_DELEGATE_WRITE;
>>> + } else {
>>> + nf = find_readable_file(fp);
>>> + deleg = NFS4_OPEN_DELEGATE_READ;
>>> + }
>>> if (!nf) {
>>> /*
>>> * We probably could attempt another open and get a read
>>> @@ -5491,11 +5498,11 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>> return ERR_PTR(status);
>>>
>>> status = -ENOMEM;
>>> - dp = alloc_init_deleg(clp, fp, odstate);
>>> + dp = alloc_init_deleg(clp, fp, odstate, deleg);
>>> if (!dp)
>>> goto out_delegees;
>>>
>>> - fl = nfs4_alloc_init_lease(dp, NFS4_OPEN_DELEGATE_READ);
>>> + fl = nfs4_alloc_init_lease(dp, deleg);
>>> if (!fl)
>>> goto out_clnt_odstate;
>>>
>>> @@ -5583,6 +5590,7 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>> struct svc_fh *parent = NULL;
>>> int cb_up;
>>> int status = 0;
>>> + u32 wdeleg = false;
>>>
>>> cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
>>> open->op_recall = 0;
>>> @@ -5590,8 +5598,6 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>> case NFS4_OPEN_CLAIM_PREVIOUS:
>>> if (!cb_up)
>>> open->op_recall = 1;
>>> - if (open->op_delegate_type != NFS4_OPEN_DELEGATE_READ)
>>> - goto out_no_deleg;
>>> break;
>>> case NFS4_OPEN_CLAIM_NULL:
>>> parent = currentfh;
>>> @@ -5617,7 +5623,9 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>> memcpy(&open->op_delegate_stateid, &dp->dl_stid.sc_stateid, sizeof(dp->dl_stid.sc_stateid));
>>>
>>> trace_nfsd_deleg_read(&dp->dl_stid.sc_stateid);
>> I'd like you to add a trace_nfsd_deleg_write(), and invoke
>> it here instead of trace_nfsd_deleg_read when NFSD hands out
>> a write delegation.
>
> Fix in v4.
>
> -Dai
>
>>
>>
>>> - open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
>>> + wdeleg = open->op_share_access & NFS4_SHARE_ACCESS_WRITE;
>>> + open->op_delegate_type = wdeleg ?
>>> + NFS4_OPEN_DELEGATE_WRITE : NFS4_OPEN_DELEGATE_READ;
>>> nfs4_put_stid(&dp->dl_stid);
>>> return;
>>> out_no_deleg:
>>> --
>>> 2.9.5
>>>
>> --
>> Chuck Lever
--
Chuck Lever
