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 C1C5920E6 for ; Wed, 24 Sep 2025 18:56:21 +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=1758740181; cv=none; b=jzORe03hNao/QCuUcW1lJTDSreTV1j0QfO0n+26j+XwMnE+16BivHrXf24znyDqZcm/ysqFPZ+/3by+gMXudYYRiFPYmpK8YAcDFy7bG7b/WgaN2m3gwyiCxcZ0Nydb4yRadiBGwbzky5oGcsqs1Z2M2QO51UBdbDfaa3kRpqt8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758740181; c=relaxed/simple; bh=lMhTvkO8dGwUlVTNt8o0UJUKsJg3OHuZKJtY8n9AoXM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jhLaqlkhI9+3ValgQSAwnEFKPRn8Dc8HwopyPCONnyAbJnjj8sp5983131jRLBi0x+x2Oc7cZHSNN74ZE32ekhUi5MNncttA1HUfQZo1R92NVXyvg/59m7ITYToDAch8+/wAamEAiI155vh10jiyLDja2pOEJEZGO39u8GF8aHI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GWcp2zHV; 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="GWcp2zHV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2225EC4CEE7; Wed, 24 Sep 2025 18:56:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758740181; bh=lMhTvkO8dGwUlVTNt8o0UJUKsJg3OHuZKJtY8n9AoXM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GWcp2zHVA49YvKjBiYDh7CurGNsBBLosajpWVZmK+W0BNvpBbtI2AwxBpYkRG4xiF Z8F4vKa4No1RtzxrhbB7U8gng+GpZYbiWYzS4CQQT5yke+rg9kOjACXq77CHLEa9bX Ns+zQcN00em/Ye12X4uzwZUVVVmC/yfSBx8X8jwkdzCRnoTMBgxs+FX8ghNbHizSrQ M5jGkREPRExwiPKO7oXk7yEFtD7sXk5rcGsmw+BZjkgKV/4lQve98SGXVQAcE4fM93 LW1gfToisAkZ7vhxfhnO3c1nqT+fLJz7EPNotFag7IQYAfOy2rPnh+AlHBl8qdkQUd /iW2ZYsi8GyeQ== Date: Wed, 24 Sep 2025 14:56:20 -0400 From: Mike Snitzer To: NeilBrown , Chuck Lever Cc: Jeff Layton , Olga Kornievskaia , Dai Ngo , Tom Talpey , linux-nfs@vger.kernel.org, Chuck Lever Subject: [RFC PATCH v3 4/3] NFSD: Implement NFSD_IO_DIRECT for NFS READ (v3 and older) [Was: "Re: [PATCH v3 3/3] NFSD: Implement NFSD_IO_DIRECT for NFS READ"] Message-ID: References: <20250922141137.632525-1-cel@kernel.org> <20250922141137.632525-4-cel@kernel.org> <19eef754-57d9-4fe4-a6e6-a481dcec470e@kernel.org> <175867132212.1696783.15488731457039328170@noble.neil.brown.name> <60960803-80b3-4ca1-9fd3-16bc1bd1dbd4@kernel.org> <175869903827.1696783.17181184352630252525@noble.neil.brown.name> 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: On Wed, Sep 24, 2025 at 11:18:53AM -0400, Mike Snitzer wrote: > > FYI, I've been testing with NFSv3. So nfsd_read -> nfsd_iter_read > > The last time I tested NFSv4 was with my DIO READ code that checked > the memory alignment with precision (albeit adding more work per IO, > which Chuck would like to avoid). We could just enable NFSD_IO_DIRECT for NFS v3 and older. And work out adding support for NFSv4 as follow-on work for next cycle? This could be folded into Patch 3/3, and its header updated to be clear that NFS v4+ isn't supported yet: diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 96792f8a8fc5a..459a29f377c2c 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1182,10 +1182,6 @@ __be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp, case NFSD_IO_BUFFERED: break; case NFSD_IO_DIRECT: - if (nf->nf_dio_read_offset_align && - !rqstp->rq_res.page_len && !base) - return nfsd_direct_read(rqstp, fhp, nf, offset, - count, eof); fallthrough; case NFSD_IO_DONTCACHE: if (file->f_op->fop_flags & FOP_DONTCACHE) @@ -1622,8 +1618,14 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp, file = nf->nf_file; if (file->f_op->splice_read && nfsd_read_splice_ok(rqstp)) err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof); - else + else { + /* Use vectored reads, for NFS v3 and older */ + if (nfsd_io_cache_read == NFSD_IO_DIRECT && + nf->nf_dio_read_offset_align && + !rqstp->rq_res.page_len && !base) + return nfsd_direct_read(rqstp, fhp, nf, offset, count, eof); err = nfsd_iter_read(rqstp, fhp, nf, offset, count, 0, eof); + } nfsd_file_put(nf); trace_nfsd_read_done(rqstp, fhp, offset, *count);