From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793123985; b=CVYo0/7+B1zonEMzPkutmPKuY1hi0zA0/m3nEwzvpGnuMweePFqSfh89nQYNn6wT5cw3 4lg+PBMk+UzWOuX1hUZ9Kfk43W9wnPmHf6KkT69FIhz2w7UesVv11L1pfxxHkEimjw9J/ aki3n3DM8s7gZg6XOoE3n5E/E51EsYk7AMOJcq8TCiqLPEZC2Pfm0sIZXgC5gtDsjYB8X qjsQFuAnBbklhfKur77s9hsGAMDdEjNM3s35eUdmBpQhE0+Sr6ZkruV/U7FrzXcJKytI1 Kv4ZaUkauoqRMaSyE2eqexYqmhBPafnVcyRkTMXhsKB0EHFVkyS1taGkpQmNyOvcEGQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793123985; h=Received:DKIM-Signature:Message-ID:Subject:From:To:Cc:Date: In-Reply-To:References:Autocrypt:Content-Type: Content-Transfer-Encoding:User-Agent:MIME-Version; bh=zNuaeVQHNQqFUJa+PqI7b/TO/F47lbspMzWZbs2KJoM=; b=oazxnNoDNC1pI14MMId2onHwZE7YSHi1vv5O4uKuwsHVkbQKMr+3ynHigX/8jENql0se eVIXItak+jozr6ktRH77neRjZVLOSSwS48jEd73/WnnpbcsKni+3Cs4J+z7ZO+vWduMfm EZqmz/HJqPJhwX+6WS4+Vlfc/YVQFb4DVTyohYoW5IAO3YWTXxYmu3qdsjdxhh8j24moF HuvxqrTGB8qLIJx53vzv0R2t8fusEwtpaQuvgIxZ4rtflG3vG0JVX8vA7HrzUAGdnRI+V pQ9aOeNajMM2iPhcLbg7bGD8ikc5r06nsYyRKewETI+hkge6x4p6BPxujuQu+IYf45w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ax7OJx6p; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B850606A31A; Tue, 27 Oct 2026 17:59:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ax7OJx6p Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CC631F01825; Tue, 27 Oct 2026 17:59:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793123985; bh=zNuaeVQHNQqFUJa+PqI7b/TO/F47lbspMzWZbs2KJoM=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=ax7OJx6p4umsu2oVnHrePRQPcEr5Z602yD1I7UIqAseRRa6me8ZFktJfQYURMg2Jv LtcrAx8nujniNItLa9TGApRpM0W2nT2CQi7gUHHIMTeOVym36GyvkI0Vf9lsLp1vVS l21xeaz/NkxPNUMJIMD0upztwHjaM75WQHGR1ZSDBKf6k2HVIp0PQ/FFO9r826Xau8 EKd8oma/FmNOz+34gMhWypP6BefzqGtBLqi55L/LZyX3uozLcvIvH/MGJcZ8bJyvom eSUPSeMRQjuQN04/YD7do5hTlBrcc7uj304pokkdZplwto5Xda4eQnWHczbnRQXW6a 6CA9BT9M/jTRg== Message-ID: <31238159b7a4753e0a10c9f8b9fdecc4b92fb2f5.camel@kernel.org> Subject: Re: [PATCH 2/6] NFSD: Apply per-export I/O modes to READ and WRITE From: Jeff Layton To: Chuck Lever Cc: NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Trond Myklebust , Anna Schumaker , Jonathan Corbet , Shuah Khan , Randy Dunlap , Mike Snitzer , Donald Hunter , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Steve Dickson , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-doc@vger.kernel.org Date: Tue, 27 Oct 2026 13:59:41 -0400 In-Reply-To: References: <20261027-export-iomode-v1-0-262ed932a036@kernel.org> <20261027-export-iomode-v1-2-262ed932a036@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn VluJH0/RcxEeFbnSaswVChNSGa7mXJrTR22lRL6ZPjdMgS2Km90haWPRc8Wolcz07Y2se0xpGVLEQ 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exports whose effective read mode is not > > buffered. Update the debugfs knob comments to match. >=20 > [ ... ] >=20 > > - if (file->f_op->splice_read && nfsd_read_splice_ok(rqstp)) > > + if (file->f_op->splice_read && nfsd_read_splice_ok(rqstp) && > > + nfsd_read_iomode(fhp->fh_export) =3D=3D NFSD_IO_BUFFERED) > > err =3D nfsd_splice_read(rqstp, fhp, file, offset, count, eof); >=20 > nfsd_io_cache_read_set() still sets nfsd_disable_splice_read whenever > the global knob is switched to dontcache or direct, so > nfsd_read_splice_ok() returns false before this per-export test is > reached. An export pinned to riomode=3Dbuffered on such a server never > gets splice; it falls through to nfsd_iter_read() and does vector > buffered reads. The same applies to the splice_ok decisions in > nfsd4_encode_read() and nfsd4_encode_read_plus_data(). >=20 > Patch 3/6 says an explicit per-export setting pins that export's > IO mode "regardless of the global knob", and that isn't quite true > now for the buffered case. >=20 > I need to think carefully about the interaction between the "disable > splice" setting, which is global, and the per-export I/O setting. >=20 Maybe disable_splice should be an export option of its own? It seems like that should be doable. > Separately, on the names of the export options: "riomode" and > "wiomode" are hard to read, and "mode" might suggest "permission bits" > to an administrator. How about read_io=3D and write_io=3D instead? They > follow the underscore style of the other multi-word export options > (no_subtree_check, root_squash, security_label) and read naturally: >=20 > /srv/data client(rw,read_io=3Ddirect,write_io=3Ddontcache) >=20 > The values buffered, dontcache, and direct then carry the meaning > without "cache" or "mode" in the name. >=20 > The name appears in the exports syntax, the nfsd.export/content > output, the netlink YAML spec, and the forthcoming nfs-utils series, > so it's worth settling before v2 and before the nfs-utils side gets > merged. >=20 Ok, I'll look at renaming them. Thanks for the initial review! --=20 Jeff Layton