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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6B5E3C7EE25 for ; Wed, 7 Jun 2023 12:17:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=E9faakThGtCW+0bU4cgq1GBsW1Ng9dSqZFBHRCf6MfU=; b=pKrZb+pVScVhdLKswBhWS8qs6Z J2zjJ3/NR2wC+MXDvFQYNbL+4yKPz8A3RrBBKvKVl4bPk/2J4mtY0XoSz/NzIwJgSxicbu8QkSDN+ JlZV5jn6r3AleRKDLnZZgCAhXQ0pxzpPivNbpTRbpvOJ0nxa7ZEvQTzvMp4hje1womt1anUyJ9enQ p8+tr3PAXQ4rlyfNpC9wFOTpAk6ERIJ6Fn4FqJLgegrV6qVNpu501LsVfPyoK+sLtllD37es7HURH NPxqm/98ZKOaGIAqyPvH4PwOWbpIlCWpBCuMusB/T4ganL+bXypIyzoRTTMjfwD0X2cAdnXhyy3V0 3wqNFdqA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q6s6A-005pFZ-0r; Wed, 07 Jun 2023 12:17:10 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q6s66-005pCh-2Y; Wed, 07 Jun 2023 12:17:08 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 52B4E6732D; Wed, 7 Jun 2023 14:16:58 +0200 (CEST) Date: Wed, 7 Jun 2023 14:16:58 +0200 From: Christoph Hellwig To: Christian Brauner Cc: Christoph Hellwig , Jens Axboe , Richard Weinberger , Josef Bacik , "Md. Haris Iqbal" , Jack Wang , Phillip Potter , Coly Li , Miquel Raynal , Vignesh Raghavendra , "Martin K. Petersen" , Chris Mason , David Sterba , Alexander Viro , "Rafael J. Wysocki" , Pavel Machek , dm-devel@redhat.com, linux-block@vger.kernel.org, linux-um@lists.infradead.org, linux-scsi@vger.kernel.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-nvme@lists.infradead.org, linux-btrfs@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH 28/31] block: replace fmode_t with a block-specific type for block open flags Message-ID: <20230607121658.GA13632@lst.de> References: <20230606073950.225178-1-hch@lst.de> <20230606073950.225178-29-hch@lst.de> <20230607-kocht-kornfeld-a249c6740e38@brauner> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230607-kocht-kornfeld-a249c6740e38@brauner> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230607_051706_969516_A3D4937D X-CRM114-Status: GOOD ( 23.78 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Jun 07, 2023 at 11:21:14AM +0200, Christian Brauner wrote: > On Tue, Jun 06, 2023 at 09:39:47AM +0200, Christoph Hellwig wrote: > > The only overlap between the block open flags mapped into the fmode_t and > > other uses of fmode_t are FMODE_READ and FMODE_WRITE. Define a new > > and FMODE_EXCL afaict FMODE_EXCL isn't used outside the block layer and removed in the last patch. > > +blk_mode_t file_to_blk_mode(struct file *file) > > +{ > > + blk_mode_t mode = 0; > > + > > + if (file->f_mode & FMODE_READ) > > + mode |= BLK_OPEN_READ; > > + if (file->f_mode & FMODE_WRITE) > > + mode |= BLK_OPEN_WRITE; > > + if (file->f_mode & FMODE_EXCL) > > + mode |= BLK_OPEN_EXCL; > > + if ((file->f_flags & O_ACCMODE) == 3) > > I really don't like magic numbers like this. I don't like them either, but this is just moved around and not new. > Groan, O_RDONLY being defined as 0 strikes again... > Becuase of this quirk we internally map > > O_RDONLY(0) -> FMODE_READ(1) > O_WRONLY(1) -> FMODE_WRITE(2) > O_RDWR(3) -> (FMODE_READ | FMODE_WRITE) O_RDWR is 2. > so checking for the raw 3 here is confusing in addition to being a magic > number as it could give the impression that what's checked here is > (O_WRONLY | O_RDWR) which doesn't make sense... Well, that is exactly what we check for. This is a 30-ish year old quirk only used in the floppy driver. > So my perference would be in descending order of preference: > > (file->f_flags & O_ACCMODE) == (FMODE_READ | FMODE_WRITE) > > or while a little less clear but informative enough for people familiar > with the O_RDONLY quirk: > > if ((file->f_flags & O_ACCMODE) == O_ACCMODE) I don't understand this part. Especially the above doesn't make any sense as FMODE_READ and FMODE_WRITE are in a completely different symbol space to O_*, and not a UAPŠ† but a kernel internal thing that could be renumbered any time.