From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milos Vyletel Date: Wed, 27 Feb 2013 13:09:48 +0000 Subject: Re: [PATCH] virtio-blk: emit udev event when device is resized Message-Id: <1972692083.62396.1361970588620.JavaMail.root@sde.cz> List-Id: References: <1361473348-7660-1-git-send-email-milos.vyletel@sde.cz> <87y5ehfczy.fsf@rustcorp.com.au> <20130225221238.GA10575@kroah.com> <16100EF6-6C55-47ED-9BBB-2C3CAC8FA37A@sde.cz> <87wqtuegs9.fsf@rustcorp.com.au> In-Reply-To: <87wqtuegs9.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Rusty Russell Cc: Greg KH , Kay Sievers , linux-kernel@vger.kernel.org, linux-hotplug@vger.kernel.org, virtualization@lists.linux-foundation.org, mst@redhat.com ----- Original Message ----- > Milos Vyletel writes: > > On Feb 25, 2013, at 5:12 PM, Greg KH wrote: > > > >> On Fri, Feb 22, 2013 at 10:14:49AM +1030, Rusty Russell wrote: > >>> Milos Vyletel writes: > >>> > >>>> When virtio-blk device is resized from host (using block_resize from > >>>> QEMU) emit > >>>> KOBJ_CHANGE uevent to notify guest about such change. This allows user > >>>> to have > >>>> custom udev rules which would take whatever action if such event occurs. > >>>> As a > >>>> proof of concept I've created simple udev rule that automatically resize > >>>> filesystem on virtio-blk device. > >>>> > >>>> ACTION="change", KERNEL="vd*", \ > >>>> ENV{RESIZE}="1", \ > >>>> ENV{ID_FS_TYPE}="ext[3-4]", \ > >>>> RUN+="/sbin/resize2fs /dev/%k" > >>>> ACTION="change", KERNEL="vd*", \ > >>>> ENV{RESIZE}="1", \ > >>>> ENV{ID_FS_TYPE}="LVM2_member", \ > >>>> RUN+="/sbin/pvresize /dev/%k" > >>> > >>> This looks fine to me, but I like to check with Greg before adding udev > >>> callouts.... Greg? > >> > >> Hm, I thought we were frowning apon running binaries from udev rules > >> these days, especially ones that might have big consequences (like > >> resizing a disk image) like this. > >> > >> Kay, am I right? > >> > >> We already emit KOBJECT_CHANGE events when block devices change, from > >> within the block core code. Why is the patch below needed instead of > >> using these events that are already generated? How are virtio block > >> devices special? > >> > >>> BTW, if this is good, it's good for stable IMHO. > >> > >> What bug does it fix? > >> > > > > It is not really a bug but it definitely is useful enhancement to have in > > stable too. I > > can imagine lots of people can benefit from this. > > But that applies to almost any enhancement :) > Good point :) > It will go in *next* merge window, not this one. > Cool, thanks. Milos