From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 1/3] Send KOBJ_ADD event after dm resume ioctl. Date: Fri, 19 Mar 2010 15:08:39 +0100 Message-ID: <4BA38567.1050106@suse.de> References: <1268920694-10960-1-git-send-email-mbroz@redhat.com> <4BA29CA4.9070000@redhat.com> <20100319090656.GR6379@soda.linbit> <4BA37B06.1040107@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4BA37B06.1040107@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids Peter Rajnoha wrote: > On 03/19/2010 10:24 AM, Kay Sievers wrote: >> No, that's what "change" is for, and we already have these "change" >> events for dm. Udev does not care if the device is ready or not, it >> synchronizes /sys and /dev, and that works just fine with "change" >> events. > = > CHANGE events, not quite... We can't even rely on these. > = > Just to mention, there's also a CHANGE event generated when > read-only flag is set for a device (this is not managed by > device-mapper of course). This one is generated even before > the actual CHANGE event that is generated when DM device is > ready to be used. > = As mentioned earlier, CHANGE events do not carry any information about _what_ has changed. The udev rules / programs are expected to check for this themselves. So from that point of view yes, you cannot simply wait for 'the' CHANGE event as you might get more than one. I guess most of this discussion could be solved if the CHANGE events would be modify to attach some enviroment variables indicating the nature of the change. EG adding 'DM_STATE=3DLIVE' or whatever is appropriate here. Cheers, Hannes -- = Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: Markus Rex, HRB 16746 (AG N=FCrnberg)