Received: by 2002:ac0:a582:0:0:0:0:0 with SMTP id m2-v6csp2113303imm; Thu, 18 Oct 2018 09:13:39 -0700 (PDT) X-Google-Smtp-Source: ACcGV638SFXGoaiiJlOyy8uJjj5FocU02ZMJD9nt3PF2Bix+i4MrLZsCZSU6iqcncpAqoFcPQuiQ X-Received: by 2002:a63:415:: with SMTP id 21-v6mr7074162pge.204.1539879219149; Thu, 18 Oct 2018 09:13:39 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1539879219; cv=none; d=google.com; s=arc-20160816; b=BtoC/88TXm7XA3DOytqGnUKxSqX9FORYUoE8abR0pwV4qUkq3w7YZxCmgS3NP8hug8 pRjzh44KvfMMGZrJeZh7QuVmXF1DTqm4pEIyeZhslaMD8ydLqeik+zW/ZbgQSRifc4cT gxdKrrhPoNp4NdPQjVPr1YBgzThOVB0z98KvYjQ/z0Pnf4su9oC7D7K37JAWHiwhnUvC bwneY4OZ0OBYsejref89CrTxmU0YMfFEs5rYlvireeNGznLoaFd+qbG6/Q9o1WAVvszK MlCg9kjOmNmOJ2TTIOEQuOdX79RHquLWXgC0pY1VrhpwlMWpB+7oFlZEwohlak+nt3N1 mvbw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:mime-version:message-id:in-reply-to:date :references:subject:cc:to:from; bh=bi+MqlQlGKiaB00INLrytHb7udEvUSLvYJbyS2WmVNs=; b=FWiR5TFXkKPcd7O2izmsZXsuQyHce2FXoJOkEQCDY91oidTH+kpfjJNNGZdjsgh7x7 tXFarxr6Cqvmb7mjDUhxLJvzAmIKCloJAQrsZmsv4IwJniaPFZlot8W5PC5OJF1wRIOD /+kjAx9N9kvNZgbQwGeX3lprVCITV9H5vwM7U+5YNURLIarK83yYMotmmodTfIyvDIPQ AXP9J0gQ/kCyDnRVQEFoi9/mWH0esJUo3wE0+Neok0YSHBjgBPufrvEPbXYG+qR1LzW1 +9hEdy3mEOgHt/NRDHQaTJhPHILqKs8IeoqGXs8g8PW72YUp77KBt3+l1j4gWa9jxPc4 HLzg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id u7-v6si21969280pgj.443.2018.10.18.09.13.21; Thu, 18 Oct 2018 09:13:39 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728513AbeJSANL (ORCPT + 99 others); Thu, 18 Oct 2018 20:13:11 -0400 Received: from albireo.enyo.de ([5.158.152.32]:59462 "EHLO albireo.enyo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727417AbeJSANL (ORCPT ); Thu, 18 Oct 2018 20:13:11 -0400 Received: from [172.17.203.2] (helo=deneb.enyo.de) by albireo.enyo.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) id 1gDAtS-0007LR-Ue; Thu, 18 Oct 2018 16:11:27 +0000 Received: from fw by deneb.enyo.de with local (Exim 4.89) (envelope-from ) id 1gDAtS-000432-OI; Thu, 18 Oct 2018 18:11:26 +0200 From: Florian Weimer To: Amir Goldstein Cc: Miklos Szeredi , linux-fsdevel , linux-kernel , linux-api@vger.kernel.org, David Howells , "Michael Kerrisk \(man-pages\)" , Andreas Dilger Subject: Re: [PATCH 2/3] uapi: get rid of STATX_ALL References: <20181018131125.6303-1-mszeredi@redhat.com> <20181018131125.6303-2-mszeredi@redhat.com> Date: Thu, 18 Oct 2018 18:11:26 +0200 In-Reply-To: (Amir Goldstein's message of "Thu, 18 Oct 2018 17:51:54 +0300") Message-ID: <87va5zw7yp.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Amir Goldstein: > On Thu, Oct 18, 2018 at 4:11 PM Miklos Szeredi wrote: >> >> Constants of the *_ALL type can be actively harmful due to the fact that >> developers will usually fail to consider the possible effects of future >> changes to the definition. >> >> Remove STATX_ALL from the uapi, while no damage has been done yet. >> > > Look. When Linus says "let's see if somebody notices" and referring to ABI > it means sooner or later someone will upgrade to newer kernel and complain > if something breaks. > > But what does it mean with UAPI change? How often do people > re-build existing programs? I, for one, build master for my > testing, but never install uapi headers from master. I just can't > wrap my head around the backward compatibiltiy nightmare a change > like this could create. So it appears that people use #ifdef STATX_ALL to check for struct statx availability. So the backwards compatibility impact is that you silently lose features in a consistent manner, which is very hard to spot. 8-( Probably not a good idea, then.