From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id 63E016B0032 for ; Fri, 17 Apr 2015 12:25:45 -0400 (EDT) Received: by paboj16 with SMTP id oj16so130153778pab.0 for ; Fri, 17 Apr 2015 09:25:45 -0700 (PDT) Received: from mailout4.w1.samsung.com (mailout4.w1.samsung.com. [210.118.77.14]) by mx.google.com with ESMTPS id pc5si17371354pac.85.2015.04.17.09.25.44 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Fri, 17 Apr 2015 09:25:44 -0700 (PDT) Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NMY00DTNLW0J650@mailout4.w1.samsung.com> for linux-mm@kvack.org; Fri, 17 Apr 2015 17:31:12 +0100 (BST) Message-id: <55313401.5080008@samsung.com> Date: Fri, 17 Apr 2015 18:25:37 +0200 From: Beata Michalska MIME-version: 1.0 Subject: Re: [RFC 1/4] fs: Add generic file system event notifications References: <1429082147-4151-1-git-send-email-b.michalska@samsung.com> <1429082147-4151-2-git-send-email-b.michalska@samsung.com> <20150417113110.GD3116@quack.suse.cz> <553104E5.2040704@samsung.com> <55310957.3070101@gmail.com> <55311DE2.9000901@redhat.com> <20150417154351.GA26736@quack.suse.cz> <55312FEA.3030905@redhat.com> In-reply-to: <55312FEA.3030905@redhat.com> Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: John Spray Cc: Jan Kara , Austin S Hemmelgarn , linux-kernel@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, hughd@google.com, lczerner@redhat.com, hch@infradead.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, kyungmin.park@samsung.com, kmpark@infradead.org, Linux Filesystem Mailing List , linux-api@vger.kernel.org On 04/17/2015 06:08 PM, John Spray wrote: > > On 17/04/2015 16:43, Jan Kara wrote: >> On Fri 17-04-15 15:51:14, John Spray wrote: >>> On 17/04/2015 14:23, Austin S Hemmelgarn wrote: >>> >>>> For some filesystems, it may make sense to differentiate between a >>>> generic warning and an error. For BTRFS and ZFS for example, if >>>> there is a csum error on a block, this will get automatically >>>> corrected in many configurations, and won't require anything like >>>> fsck to be run, but monitoring applications will still probably >>>> want to be notified. >>> Another key differentiation IMHO is between transient errors (like >>> server is unavailable in a distributed filesystem) that will block >>> the filesystem but might clear on their own, vs. permanent errors >>> like unreadable drives that definitely will not clear until the >>> administrator takes some action. It's usually a reasonable >>> approximation to call transient issues warnings, and permanent >>> issues errors. >> So you can have events like FS_UNAVAILABLE and FS_AVAILABLE but what use >> would this have? I wouldn't like the interface to be dumping ground for >> random crap - we have dmesg for that :). > In that case I'm confused -- why would ENOSPC be an appropriate use of this interface if the mount being entirely blocked would be inappropriate? Isn't being unable to service any I/O a more fundamental and severe thing than being up and healthy but full? > > Were you intending the interface to be exclusively for data integrity issues like checksum failures, rather than more general events about a mount that userspace would probably like to know about? > > John > I think we should support both and leave the decision on what is to be reported or not to particular file systems keeping it to a reasonable extent, of course. The interface should hand it over to user space - acting as a go-between. I would though avoid any filesystem specific events (when it comes to specifying those), keeping it as generic as possible. BR Beata -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org