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[209.132.180.67]) by mx.google.com with ESMTP id z1si1881049pgi.498.2019.07.25.11.16.16; Thu, 25 Jul 2019 11:16:30 -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; dkim=fail header.i=@infradead.org header.s=bombadil.20170209 header.b=Fce7whCG; 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 S1727997AbfGYR6g (ORCPT + 99 others); Thu, 25 Jul 2019 13:58:36 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:53586 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726432AbfGYR6g (ORCPT ); Thu, 25 Jul 2019 13:58:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=XQ6rI4d7gxBNj6SNlmzuGaSaA8CuaLNKV7YKP78h+Cc=; b=Fce7whCGz/V/DBAMhW7HcJDlK hsk1SqJTkIq8akKJSz8MfOzYVgM62isRP3FAAyJ8ha68W6y08DNv4jdLNi14uNUgu2qLXe/0XLzO1 wTiABPnQYx/qD4NyVm0SnpQYdPhRj2Zhg+5m0JhHFr1U36CMI6AB0yTT1tlD2/ZAazHFfobvyoQUU +0dAMO8k5Q+PqJTwUiJILur+fLkMJp5XZbWNfqEW0Kvo/EgBuYuhv2PiDLLv0uylGsTozlXrN5SXN OWleTSJSPsOFaaptcq92Wti/80HwUuUrV5vxt8qXqsu0JBPnGBHZNY4Qv3V/u7Xt4hMiDt0elbHEr 6ZBjuBohw==; Received: from willy by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hqi0g-0004X8-K9; Thu, 25 Jul 2019 17:58:34 +0000 Date: Thu, 25 Jul 2019 10:58:34 -0700 From: Matthew Wilcox To: Logan Gunthorpe Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig , Sagi Grimberg , Keith Busch , Jens Axboe , Chaitanya Kulkarni , Max Gurtovoy , Stephen Bates , Alexander Viro Subject: Re: [PATCH v6 02/16] chardev: introduce cdev_get_by_path() Message-ID: <20190725175834.GB30641@bombadil.infradead.org> References: <20190725172335.6825-1-logang@deltatee.com> <20190725172335.6825-3-logang@deltatee.com> <20190725174032.GA27818@kroah.com> <682ff89f-04e0-7a94-5aeb-895ac65ee7c9@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <682ff89f-04e0-7a94-5aeb-895ac65ee7c9@deltatee.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 25, 2019 at 11:53:20AM -0600, Logan Gunthorpe wrote: > > > On 2019-07-25 11:40 a.m., Greg Kroah-Hartman wrote: > > On Thu, Jul 25, 2019 at 11:23:21AM -0600, Logan Gunthorpe wrote: > >> cdev_get_by_path() attempts to retrieve a struct cdev from > >> a path name. It is analagous to blkdev_get_by_path(). > >> > >> This will be necessary to create a nvme_ctrl_get_by_path()to > >> support NVMe-OF passthru. > > > > Ick, why? Why would a cdev have a "pathname"? > > So we can go from "/dev/nvme0" (which points to a char device) to its > struct cdev and eventually it's struct nvme_ctrl. Doing it this way also > allows supporting symlinks that might be created by udev rules. But you're not really trying to go from a string to a chardev. You're trying to go from a nvmet_subsys to a chardev. Isn't there a better way to link the two somewhere else? (I must confess that once I would have known the answer to this, but the NVMe subsystem has grown ridiculously complex and I can no longer fit it in my head)