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Date:   Thu, 29 Jun 2023 09:16:14 -0700
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Subject: Re: [PATCH v6 5/5] NFSD: add counter for write delegation recall due
 to conflict GETATTR
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To:     Chuck Lever <cel@kernel.org>
Cc:     chuck.lever@oracle.com, jlayton@kernel.org,
        linux-nfs@vger.kernel.org
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On 6/29/23 8:07 AM, Chuck Lever wrote:
> On Wed, Jun 28, 2023 at 07:36:16PM -0700, Dai Ngo wrote:
>> Add counter to keep track of how many times write delegations are
>> recalled due to conflict with GETATTR.
> Should this wee patch be squashed into 3/5 ?

Yes, will squash this into 3/5.

>
> The patch description ought to explain /why/ we want to track
> GETATTR conflicts. (even if you squash it into 3/5). Mostly I'm
> trying to get the important design choices written down so we
> can remember them in a year or two.

will do.

-Dai

>
>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 1 +
>>   fs/nfsd/stats.c     | 2 ++
>>   fs/nfsd/stats.h     | 7 +++++++
>>   3 files changed, 10 insertions(+)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 2d2656c41ffb..6ce95e738359 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -8410,6 +8410,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode)
>>   			}
>>   break_lease:
>>   			spin_unlock(&ctx->flc_lock);
>> +			nfsd_stats_wdeleg_getattr_inc();
>>   			status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
>>   			if (status != nfserr_jukebox ||
>>   					!nfsd_wait_for_delegreturn(rqstp, inode))
>> diff --git a/fs/nfsd/stats.c b/fs/nfsd/stats.c
>> index 777e24e5da33..63797635e1c3 100644
>> --- a/fs/nfsd/stats.c
>> +++ b/fs/nfsd/stats.c
>> @@ -65,6 +65,8 @@ static int nfsd_show(struct seq_file *seq, void *v)
>>   		seq_printf(seq, " %lld",
>>   			   percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_NFS4_OP(i)]));
>>   	}
>> +	seq_printf(seq, "\nwdeleg_getattr %lld",
>> +		percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_WDELEG_GETATTR]));
>>   
>>   	seq_putc(seq, '\n');
>>   #endif
>> diff --git a/fs/nfsd/stats.h b/fs/nfsd/stats.h
>> index 9b43dc3d9991..cf5524e7ca06 100644
>> --- a/fs/nfsd/stats.h
>> +++ b/fs/nfsd/stats.h
>> @@ -22,6 +22,7 @@ enum {
>>   	NFSD_STATS_FIRST_NFS4_OP,	/* count of individual nfsv4 operations */
>>   	NFSD_STATS_LAST_NFS4_OP = NFSD_STATS_FIRST_NFS4_OP + LAST_NFS4_OP,
>>   #define NFSD_STATS_NFS4_OP(op)	(NFSD_STATS_FIRST_NFS4_OP + (op))
>> +	NFSD_STATS_WDELEG_GETATTR,	/* count of getattr conflict with wdeleg */
>>   #endif
>>   	NFSD_STATS_COUNTERS_NUM
>>   };
>> @@ -93,4 +94,10 @@ static inline void nfsd_stats_drc_mem_usage_sub(struct nfsd_net *nn, s64 amount)
>>   	percpu_counter_sub(&nn->counter[NFSD_NET_DRC_MEM_USAGE], amount);
>>   }
>>   
>> +#ifdef CONFIG_NFSD_V4
>> +static inline void nfsd_stats_wdeleg_getattr_inc(void)
>> +{
>> +	percpu_counter_inc(&nfsdstats.counter[NFSD_STATS_WDELEG_GETATTR]);
>> +}
>> +#endif
>>   #endif /* _NFSD_STATS_H */
>> -- 
>> 2.39.3
>>