On 04/08/14 at 02:14am, Zbigniew Jędrzejewski-Szmek wrote: > On Mon, Apr 07, 2014 at 03:10:14PM -0400, Vivek Goyal wrote: > > On Mon, Apr 07, 2014 at 10:07:20PM +0400, Andrey Borzenkov wrote: > > > В Mon, 7 Apr 2014 13:40:17 -0400 > > > Vivek Goyal <vgo...@redhat.com> пишет: > > > > > > > > > > > Defining a new target which by default waits for all the local fs target > > > > sounds interesting. Again, I have the question, what will happen to > > > > local-fs-all.target if some device does not show up and say one of the > > > > mounts specified in /etc/fstab fails. > It result is different for Requires= and for Wants=. Iff there's a chain > of Requires= from the failing unit (.device in this case) to the target unit > it will fail. Otherwise, it'll just be delayed. If, as I suggested above > local-fs-all.target > would have Requires= on the .mount units, then your unit could still have > Wants=/After=local-fs-all.target, and it'll be started even if some mounts > fail. > > > > > What we want is. > > > > > > > > - Wait for all devices to show up as specified in /etc/fstab. Run fsck > > > > on devices. Mount devices to mount points specified. > > > > > > > > - If everything is successful, things are fine and local-fs-all.target > > > > will be reached. > > > > > > > > - If some device does not show up, or if fsck fails or mount fails, > > > > still > > > > local-fs-all.target should reach so that kdump module can detect that > > > > failure happened and can take alternative action. > Alternatively, you can specify a soft depenendency on local-fs-all.target by > using Wants=local-fs-all.target. I think this is preferable, because we want > local-fs-all.target to be as similar as possible to local-fs.target, which > has Requires= on the mount points.
Actually, With current implementation, whether "Wants" or "Requires" depends on if "nofail" is specified. > > With this caveat, this should all be satisfied with my proposal. > > > > You can use OnFailure= to define unit(s) started when > > > local-fs-all.target fails. But it sounds like you are not really > > > interested in *all* filesystems, but in specific fileststems defined in > > > kdump configuration. > > > > Kdump scripts registers with dracut as pre-pivot hook. And I believe > > that in initramfs environments /etc/fstab does not contain all > > filesystems. It prmarily contains root and any file system specified > > on dracut command line using --mount option during initramfs generation. > > > > So my understanding that given the fact that /etc/fstab is minimal in > > initramfs, we should be fine waiting for all the fs specified. > > > > Given the fact that we run under dracut pre-pivot hook callback, I think > > dracut-pre-pivot.service wil have to create a dependency to run after > > local-fs-all.target is reached. > Hm, maybe. It would be good to get some input from Harald here. > This is pretty specialized, so maybe it'd be better to have a separate unit > positioned before or after or parallel to dracut-pre-pivot.service. > > > Now I am not sure who will generate local-fs-all.target. > It would become a standard unit in systemd, like local-fs.target. > Mount units would be added to this target by fstab-generator. > > > If dracut > > generates it then dracut will also specify OnFailure=. Question will > > still remain how dracut modules will communicate to dracut that what > > to run after local-fs-all.target fails. > > > > In fact if dracut is doing all this, we don't have to create a separate > > target. Right now we force "nofail" so that if mount fails, initrd.target > > is still reached. > > > > If we can create a separate service to just handle failures, then we > > probably should be able to spcify OnFailure=dracut-failure-hander.service > > in right file and as modules to register their failure handler hooks > > there. > > > > Something like create new hook called pre-pivot-failure and modules > > register a hook to handle pre-pivot-failure. Then kdump can get the > > control and handle failure. > > > > And this should allow dracut pre pivot service to specify to launch > > dracut-failure-handler.service upon failure. > > > > > > > > > For example, > > > > > > > > Asssume a user wants to save vmcore to nfs destination. Now for > > > > whatever > > > > reason, nfs target could not be mounted. In that case kdump will still > > > > like to get control and alternatively save dump to local root fs. > > > > > > > > > > Without knowing details it sounds like RequiresMountsFor is more > > > appropriate (and can be set by generator based on actual kdump > > > configuration). > > > > I am not sure how is it useful for this case. dracut already generates > > all dependencies and puts them in /etc/fstab. And only entries in > > /etc/fstab should be which dracut wants. So I guess we should be fine > > and not need using RequiresMountsFor. > > Zbyszek _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel