From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D532548A2CA; Wed, 17 Jun 2026 15:25:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781709908; cv=none; b=iMbgBS80X4laKoeypsOmRm/oLUh7iFAFmZMfMSFdmLwnnVGxBrkoSabq4VaQoo7gNkUNZV3LAfii20A4P1kERgtYRUKsAX7jpxzT7qsXGhiCRl0te0WWrvUlt0g9DM/zdSXhiMPJBtjE4YC3hlj/JFZpStV6jE6TnvMp0ffsL9c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781709908; c=relaxed/simple; bh=G3nsRbRYDgcR4h3AU7P9KmhT57vxPb/5l1bzRXRNwvk=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Lcg0MgQPgvZl8tU+oI7Er6DtKfAxXjj7a4Ng8y/y+9VtwfUbE/e9+UPi3Q9lwuay3Xvf85L5/mZolV8BH4AptQ/qXrM7JUF8uYobec8eGmS43yuWlkeImPAOEUiwEeDEAN13Dgy3bDxOZvwu6z8spoW8oxA+V4loe8wuwl9K6fY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=W3wNTDV3; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="W3wNTDV3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A4671F000E9; Wed, 17 Jun 2026 15:25:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781709905; bh=IJK14lF7duaEy/Or+GjFZVXYYC018pYwcPVnlxHKMMY=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=W3wNTDV3b9ehPVis4Z0WKzW0DW/sY63QwoPY8lXBZVGNMB57QalzifTPoIOfNeQKm zYuDOdgBJcR1O6lxM8jkPjhyF4IvQ09lqDTlnT7sxelQgkRN/fmcsZYYGN6Wic1JHb Z8dueI9Me4A+/xYeHWiXbEqye+kBZUh0M5bB0ULhQaP3hYaDOSKSavdWKhE1BZdTEs JhMT6Yb0W0ug8ez5HeQEdX9YbdDpxQseS8kIx3lybTty1tHH2Hg7qOC9ex51Q+kaaP inKmj6g8Htk8MZf7Dag9thYX5Qun2piNBsMXXgiSzDhv6hed9csQ9LgjLxiOZiQT5I YYsGkHzBfjX1A== Message-ID: Subject: Re: [PATCH v4 3/4] nfsd: implement server-stats-get netlink handler From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: Trond Myklebust , Anna Schumaker , Steve Dickson , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 17 Jun 2026 11:25:02 -0400 In-Reply-To: References: <20260616-exportd-netlink-v4-0-03505aee3883@kernel.org> <20260616-exportd-netlink-v4-3-03505aee3883@kernel.org> <657f71a2c6dc1e817be57e40431a6578281ea823.camel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2026-06-17 at 09:18 -0400, Chuck Lever wrote: >=20 > On Wed, Jun 17, 2026, at 7:07 AM, Jeff Layton wrote: > > On Tue, 2026-06-16 at 20:57 -0400, Chuck Lever wrote: > > > Hey Jeff - > > >=20 > > > On Tue, Jun 16, 2026, at 8:45 AM, Jeff Layton wrote: > > > > Implement nfsd_nl_server_stats_get_dumpit() which exposes the > > > > NFS server statistics currently available via /proc/net/rpc/nfsd > > > > through the nfsd generic netlink family. > > > >=20 > > > > The handler uses a dump operation to stream statistics across > > > > multiple netlink messages: > > > >=20 > > > > - First message: all scalar stats (reply cache, filehandle, > > > > IO, network, RPC) plus per-version procedure counts > > > > (proc2/3/4-ops) using per-netns vs_count arrays. > > > >=20 > > > > - Subsequent messages: NFSv4 per-operation counts > > > > (proc4ops-ops), one entry per message, using cb->args[0] > > > > to track the current operation index across dump calls. > > > >=20 > > > > This allows nfsstat to retrieve server statistics via netlink > > > > with a procfs fallback for older kernels. > > > >=20 > > > > Assisted-by: Claude:claude-opus-4-6 > > > > Signed-off-by: Jeff Layton > > > > --- > > > > Documentation/netlink/specs/nfsd.yaml | 105 +++++++++++++++++ > > > > fs/nfsd/netlink.c | 5 + > > > > fs/nfsd/netlink.h | 2 + > > > > fs/nfsd/nfsctl.c | 206 ++++++++++++++++++++++= ++++++++++++ > > > > include/uapi/linux/nfsd_netlink.h | 35 ++++++ > > > > 5 files changed, 353 insertions(+) > > >=20 > > > The procfs output in nfsd_show() emits one more counter that this dum= p > > > handler drops: wdeleg_getattr (NFSD_STATS_WDELEG_GETATTR), printed at > > > the end of the CONFIG_NFSD_V4 block in fs/nfsd/stats.c, right after > > > proc4ops. The netlink dump stops after proc4ops-ops and sets > > > cb->args[0] =3D -1, so the write-delegation GETATTR-conflict counter = never > > > goes out on the wire. > > >=20 > > > There's no schema slot for it either: the server-stats attribute-set > > > ends at proc4ops-ops, so a consumer that prefers netlink and only fal= ls > > > back to procfs on an old kernel loses this counter on every kernel ne= w > > > enough to support server-stats-get. > > >=20 > > > I Suggest: > > >=20 > > > - add a wdeleg-getattr (u64) attribute to the server-stats > > > attribute-set in nfsd.yaml and list it under the dump reply > > > attributes; > > >=20 > > > - add NFSD_A_SERVER_STATS_WDELEG_GETATTR to the uapi enum, after > > > PROC4OPS_OPS and before __NFSD_A_SERVER_STATS_MAX so existing > > > values don't shift; > > >=20 > > > - emit it as a single scalar in the start =3D=3D 0 message, wrapped i= n > > > CONFIG_NFSD_V4 to match the procfs side. > > >=20 > >=20 > > This omission was intentional. The stated purpose of this patchset was > > to convert nfsstat to use netlink. nfsstat does not access or display > > this field today. Without something that consumes this stat, I don't > > see the point of adding it here. We can always add it later when/if it > > becomes useful to userland. >=20 > If we were adding a greenfield kernel-userspace API, I would agree. > However, this API is meant to be compatible with the existing > procfs API, so it should match to prevent a regression (I'm not > aware of a consumer, this is only a general guideline). >=20 > For future reference: since a missing feature cannot be expressed > in a patch's diff body, your intention to exclude this field could > be mentioned in the commit message. >=20 >=20 > > Is there something that accesses this today that I'm not aware of? If > > not, is there some future intent to add this to nfsstat? >=20 > I think nfsstat should display the wdeleg-getattr field. It has simply > been forgotten. >=20 Ok. I'll plan to add it to the interface and send it in v5. nfs-utils will need a follow-on patch to display the value. No promises on when I'll do that, but it shouldn't be too hard. --=20 Jeff Layton