From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 558621684B0 for ; Wed, 22 Oct 2025 21:09:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761167371; cv=none; b=i58ldRx0hPLoMwusRHXOr6x1GKZEFeJn9QtZa3Ul4yvvQ9G+kOzo+7+oLW3gAtfO1QLY8KWqbzY/O7eHUb448RoUzG+QLgEUC4LK6HxPX0oy9WS5GbCoYRoXXoWRefelk+/R0T68tBmfiTipVZpVo9tFowcZTPe+1bwMbvcFqZk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761167371; c=relaxed/simple; bh=ZRpPVkA7SQoGuTD+JZ3nt3YulFCU3Qc6LbV47f9/GxE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hDA/sFYP1T5NMDTCTRi/e9Nzn8yDmocshW21nbOw0NJ8IRN8AbbNLZCb7zS4wTHfikwRRvtjQMEvl6IaoRuJOiKGDRjb6Mji6CEzjC7tlkC//FbiYpgkQPHM20+DJFx0PjSMkTEBOvXw4D5v6nNrwh4mRqojRnDwpZ4382JUWxE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pb22GTQz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Pb22GTQz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C92EFC4CEE7; Wed, 22 Oct 2025 21:09:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761167371; bh=ZRpPVkA7SQoGuTD+JZ3nt3YulFCU3Qc6LbV47f9/GxE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Pb22GTQz1UGu2nz8dfSrENXf0xWBdaQN3nK9J/4cYgTjrSbSlchkXJORPOQac1GAS MWip1Hj7iTj1D2c9M2ZUCf/V5HKH2iVSU8TeM9LO/+S1786JEnwzPX/WnsraV+nQJt j9BDV+QKB9f+qH8yh5VV7SN5FgV1WZzPg8jpNAdLLS4CtcVlqL7TOF4CmX1lm38Q2u o2hrdu5cFDH2Gth4Jqb/UnFyldoKls4Jiv2JIQ6zwss2auzmJBgRxjK2zR48Kmdy6X mm3WiP+fxilm9kdS+67YyYSnto6c38Lq2uFk9te+DLuT3sz87isMizzYAH7ZK/k7CN g6ANAmtQeBuew== Date: Wed, 22 Oct 2025 17:09:29 -0400 From: Mike Snitzer To: Chuck Lever Cc: NeilBrown , Jeff Layton , Olga Kornievskaia , Dai Ngo , Tom Talpey , linux-nfs@vger.kernel.org Subject: Re: [PATCH v6 4/5] NFSD: Implement NFSD_IO_DIRECT for NFS WRITE Message-ID: References: <20251022192208.1682-1-cel@kernel.org> <20251022192208.1682-5-cel@kernel.org> <47c1ef78-4864-49bf-99c3-7a0112bca01e@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47c1ef78-4864-49bf-99c3-7a0112bca01e@kernel.org> On Wed, Oct 22, 2025 at 03:27:02PM -0400, Chuck Lever wrote: > On 10/22/25 3:22 PM, Chuck Lever wrote: > > @@ -1311,6 +1484,9 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, > > if (sb->s_export_op) > > exp_op_flags = sb->s_export_op->flags; > > > > + /* cel: UNSTABLE buffered WRITEs might want some form of throttling > > + * as well to prevent clients from pushing writes to us faster > > + * than they can be flushed onto durable storage */ > > if (test_bit(RQ_LOCAL, &rqstp->rq_flags) && > > !(exp_op_flags & EXPORT_OP_REMOTE_FS)) { > > /* > > Note: the above is an open question. I don't intend to merge this patch > with the above comment included. Such a mechanism would benefit all NFSD_IO modes. As-is, even NFSD_IO_DIRECT isn't sufficient to ensure client's forward progress if NFS client application is using buffered IO -- because the client itself can then enter page reclaim (when it exhausts its memory because it doesn't get any back pressure).