From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kay Sievers Subject: Re: [PATCH 001 of 6] md: Send online/offline uevents when an md array starts/stops. Date: Wed, 08 Nov 2006 12:14:42 +0100 Message-ID: <1162984482.16735.25.camel@pim.off.vrfy.org> References: <20061031164814.4884.patches@notabene> <1061031060046.5034@suse.de> <20061031211615.GC21597@suse.de> <3ae72650611020413q797cf62co66f76b058a57104b@mail.gmail.com> <17737.58737.398441.111674@cse.unsw.edu.au> <1162475516.7210.32.camel@pim.off.vrfy.org> <17738.59486.140951.821033@cse.unsw.edu.au> <1162542178.14310.26.camel@pim.off.vrfy.org> <17742.32612.870346.954568@cse.unsw.edu.au> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <17742.32612.870346.954568@cse.unsw.edu.au> Sender: linux-raid-owner@vger.kernel.org To: Neil Brown Cc: Greg KH , Andrew Morton , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-raid.ids On Mon, 2006-11-06 at 11:18 +1100, Neil Brown wrote: > On Friday November 3, kay.sievers@vrfy.org wrote: > > The persistent naming rules for /dev/disk/by-* are causing this. Md > > devices will probably just get their own rules file, which will handle > > this and which can be packaged and installed along with the md tools. > I'm still a bit concerned about the open->add->open infinite loop. > If anyone opens /dev/mdX while it isn't active (e.g. to check if it is > active), that will (given a patch that I would like to include) cause > and ADD event which will cause udev to start it's loop again. > Can we make udev ignore ADD for md and only watch for CHANGE? Is there a sysfs file or something similar(we could also call a md-tool) udev could look at, before it tries to open the device? Like: KERNEL=="md*", ATTR{state}=="active", IMPORT{program}= ... If we currently ignore the "add" event, then we will not hook into the coldplug logic, where "add" events are requested for all devices to do the initial setup after bootup. If we can't read the state of the md device, to see if it's safe to open the device, we would need to be smarter with the coldplug logic by requesting "change" events if necessary, or by passing a "coldplug" flag with the synthesized event. Thanks, Kay