From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ECA35CA9EC7 for ; Sat, 2 Nov 2019 22:30:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B2FFD20862 for ; Sat, 2 Nov 2019 22:30:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=amacapital-net.20150623.gappssmtp.com header.i=@amacapital-net.20150623.gappssmtp.com header.b="CkSX5kc/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727303AbfKBWax (ORCPT ); Sat, 2 Nov 2019 18:30:53 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:45486 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727232AbfKBWaw (ORCPT ); Sat, 2 Nov 2019 18:30:52 -0400 Received: by mail-pg1-f196.google.com with SMTP id r1so8707845pgj.12 for ; Sat, 02 Nov 2019 15:30:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=xB2VFGUZyiF2VFPR++wvNyybS4M2ews4nSbm+M32oPk=; b=CkSX5kc/xSP4pt89qT83QwNwQ7pjcK33im2ZlbhbYQXnvP8/g2zNUH0NSVCIYSeeSq j3Y5a76YdXpv39h+TCcl7eR3A2Zaq4m0LwZhwfjaSqxtIx+DoyS9Y8N34jYCjLZlOcpU OacyhB7MI78+ikrdnLdb5UldAwtetjPopJeULyZutottZOgK28zSZK4tt8sPv8dzOYcJ 3h7oi0dTnHFvGd06RvAeCEs8oTRUkjWHbmdWP2/HCclucDdQa0KYua0Tf2SOsOmv0L2c fwG5fQAv5NM6nNXrVTQh5NPv3OEq1btThojafBbfJ0IOFz01EE/XwSfA7caDXfwTSgL3 TBwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=xB2VFGUZyiF2VFPR++wvNyybS4M2ews4nSbm+M32oPk=; b=lU/ovUgfU4/M1v7Bf60wWHBa1bW3nxdGv7HBguEuXClT3Nlx+eayUHtzofD2QurxFF tMidS9DDWxgfrqUbyvOhg/ooNwR9sRYyLciNOz5KXZ2D+1NvzcykpmNm0ba1awxo69AV A3tMh0vamn0uWoe4wx2wlaSBJ4ZA0eJszbUIIDEjJU4RZau98oVMp3wxAy/2cund0wfU jbthVFSNGLAt+Q5NZVmdBpbNRZEzZ7bbZEPQvFp31DU6Qx75vse3eCT/tZiX2bNYQQZm Fxf4b/ZWoQ83lKNLvXGTqJtHB4RSpouLBA7hzxC6q4Pc387OdT6L+5C63wqPDk2z8Nfp w8Ow== X-Gm-Message-State: APjAAAWCG0yIMMIOI1ulaKGdI3vpzPct3tKjNxXc3rQ8RmRmmtav4jSN LgXJVlrh4aWc6EI6433PRnrmnw== X-Google-Smtp-Source: APXvYqzDRQiggB/0IWOZncaQ86RpbPc/jYJAjFDxSvO1yjd56TQhdj02MFsX+oGquyWY0UEfcJYLwg== X-Received: by 2002:a63:cf46:: with SMTP id b6mr21945917pgj.90.1572733851860; Sat, 02 Nov 2019 15:30:51 -0700 (PDT) Received: from ?IPv6:2600:1010:b067:e6ce:10dd:e058:94b7:feca? ([2600:1010:b067:e6ce:10dd:e058:94b7:feca]) by smtp.gmail.com with ESMTPSA id e17sm9438491pgg.5.2019.11.02.15.30.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 02 Nov 2019 15:30:50 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Andy Lutomirski Mime-Version: 1.0 (1.0) Subject: Re: [RFC PATCH 11/10] pipe: Add fsync() support [ver #2] Date: Sat, 2 Nov 2019 15:30:49 -0700 Message-Id: References: Cc: David Howells , Konstantin Khlebnikov , Rasmus Villemoes , Greg Kroah-Hartman , Peter Zijlstra , Nicolas Dichtel , raven@themaw.net, Christian Brauner , keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-block , LSM List , linux-fsdevel , Linux API , Linux Kernel Mailing List In-Reply-To: To: Linus Torvalds X-Mailer: iPhone Mail (17A878) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: > On Nov 2, 2019, at 3:04 PM, Linus Torvalds = wrote: >=20 > =EF=BB=BFOn Sat, Nov 2, 2019 at 1:31 PM Andy Lutomirski wrote: >>=20 >> Add in the fact that it=E2=80=99s not obvious that vmsplice *can* be used= correctly, and I=E2=80=99m wondering if we should just remove it or make it= just do write() under the hood. >=20 > Sure it can. Just don't modify the data you vmsplice. It's really that sim= ple. So you allocate memory, vmsplice, and munmap() without reusing it? Just pla= in free() won=E2=80=99t be good enough. I suspect the TLB overhead will make= this a loss in most workloads? Or maybe you vmsplice from a read-only mapping of a file that you know no on= e modifies? This could be useful, but you can just splice() from the file d= irectly.=