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Date:   Wed, 19 Jul 2023 22:45:56 +0200
From:   Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
To:     NeilBrown <neilb@suse.de>
Cc:     Lorenzo Bianconi <lorenzo@kernel.org>, linux-nfs@vger.kernel.org,
        chuck.lever@oracle.com, jlayton@kernel.org
Subject: Re: [PATCH v3] NFSD: add rpc_status entry in nfsd debug filesystem
Message-ID: <ZLhLhAyvdPh/HnSa@lore-desk>
References: <4aa3c87872031ca42d411ed60169c6daa951620b.1689610081.git.lorenzo@kernel.org>
 <168963056470.1518.10737362406173956339@noble.neil.brown.name>
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[...]
>=20
> The fact that RQ_BUSY is set doesn't mean that the various fields you
> are sampling are valid or stable.
>=20
> I suggest you add add a counter to the rqstp which is incremented from
> even to odd after parsing a request - including he v4 parsing needed to
> have a sable ->opcnt - and then incremented from odd to even when the
> request is complete.
> Then this code samples the counter, skips the rqst if the counter is
> even, and resamples the counter after collecting the data.  If it has
> changed, the drop the record.

Hi Neil,

thx for the review. Ack, I will look into it.

>=20
> > +
> > +			seq_printf(m,
> > +				   "0x%08x 0x%08lx 0x%08x NFSv%d %s %016lld",
> > +				   be32_to_cpu(rqstp->rq_xid), rqstp->rq_flags,
> > +				   rqstp->rq_prog, rqstp->rq_vers,
> > +				   svc_proc_name(rqstp),
> > +				   ktime_to_us(rqstp->rq_stime));
> > +
> > +			if (rqstp->rq_addr.ss_family =3D=3D AF_INET)
> > +				seq_printf(m, " %pI4 %pI4",
> > +					   &((struct sockaddr_in *)&rqstp->rq_addr)->sin_addr,
> > +					   &((struct sockaddr_in *)&rqstp->rq_daddr)->sin_addr);
> > +			else if (rqstp->rq_addr.ss_family =3D=3D AF_INET6)
> > +				seq_printf(m, " %pI6 %pI6",
> > +					   &((struct sockaddr_in6 *)&rqstp->rq_addr)->sin6_addr,
> > +					   &((struct sockaddr_in6 *)&rqstp->rq_daddr)->sin6_addr);
> > +			else
> > +				seq_printf(m, " unknown:%hu unknown:%hu",
> > +					   rqstp->rq_addr.ss_family,
> > +					   rqstp->rq_daddr.ss_family);
>=20
> The above code looks a lot like svc_print_addr().  Can we use the same
> code?  Do they need to be different.

ack, I will look into it.

Regards,
Lorenzo

>=20
> NeilBrown
>=20
>=20
> > +#ifdef CONFIG_NFSD_V4
> > +			if (rqstp->rq_vers =3D=3D NFS4_VERSION &&
> > +			    rqstp->rq_proc =3D=3D NFSPROC4_COMPOUND) {
> > +				/* NFSv4 compund */
> > +				struct nfsd4_compoundargs *args =3D rqstp->rq_argp;
> > +				struct nfsd4_compoundres *resp =3D rqstp->rq_resp;
> > +
> > +				while (resp->opcnt < args->opcnt) {
> > +					struct nfsd4_op *op =3D &args->ops[resp->opcnt++];
> > +
> > +					seq_printf(m, " %s%s", nfsd4_op_name(op->opnum),
> > +						   resp->opcnt < args->opcnt ? ":" : "");
> > +				}
> > +			}
> > +#endif /* CONFIG_NFSD_V4 */
> > +			seq_puts(m, "\n");
> > +		}
> > +	}
> > +
> > +	rcu_read_unlock();
> > +
> > +	return 0;
> > +}
> > +
> > +/**
> > + * nfsd_rpc_status_open - Atomically copy a write verifier
> > + * @inode: entry inode pointer.
> > + * @file: entry file pointer.
> > + *
> > + * This routine dumps pending RPC requests info queued into nfs server.
> > + */
> > +int nfsd_rpc_status_open(struct inode *inode, struct file *file)
> > +{
> > +	struct nfsd_net *nn =3D net_generic(inode->i_sb->s_fs_info, nfsd_net_=
id);
> > +
> > +	mutex_lock(&nfsd_mutex);
> > +	if (!nn->nfsd_serv) {
> > +		mutex_unlock(&nfsd_mutex);
> > +		return -ENODEV;
> > +	}
> > +
> > +	svc_get(nn->nfsd_serv);
> > +	mutex_unlock(&nfsd_mutex);
> > +
> > +	return single_open(file, nfsd_rpc_status_show, inode->i_private);
> > +}
> > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
> > index 587811a002c9..44eac83b35a1 100644
> > --- a/net/sunrpc/svc.c
> > +++ b/net/sunrpc/svc.c
> > @@ -1629,7 +1629,7 @@ const char *svc_proc_name(const struct svc_rqst *=
rqstp)
> >  		return rqstp->rq_procinfo->pc_name;
> >  	return "unknown";
> >  }
> > -
> > +EXPORT_SYMBOL_GPL(svc_proc_name);
> > =20
> >  /**
> >   * svc_encode_result_payload - mark a range of bytes as a result paylo=
ad
> > --=20
> > 2.41.0
> >=20
> >=20
>=20

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