On 04/18/2016 02:25 PM, Sage Weil wrote: > On Mon, 18 Apr 2016, Peter Rajnoha wrote: >> Hi! >> >> I'm resending original mail to this list after initial >> discussion with Loic Dachary so others can chime in. Loic >> says these rules were there to workaround certain problems >> on Centos 6 only and that it can be discarded now. >> >> Please, read original mail below: >> >> === >> >> We've just noticed 60-ceph-partuuid-workaround.rules. >> >> You added a patch some time ago which made these rules >> to be applied for DM devices too: >> >> https://github.com/ceph/ceph/commit/42ad86e14e352f2a3a33e774224f1789f268da83 >> >> The problem we've spotted and hit recently is that >> these rules call blkid which opens all DM devices now >> on uevents. However, not all DM devices are suitable >> for scanning as they may not be prepared fully yet. >> We use various flags in DM (and its subsystems like LVM) >> to avoid these scans and for all the rules we don't manage, >> there's DM_UDEV_DISABLE_OTHER_RULES_FLAG that needs to >> be checked in these "foreign" rules before opening such >> DM device (which includes running blkid). >> >> Otherwise, we may end up with errors where some DM subsystem >> needs to close the device or do some initialization on this >> device before making it public by dropping the >> DM_UDEV_DISABLE_OTHER_RULES_FLAG. So we need to make sure >> these things are in sync - the scan can't be run on all DM >> devices, it's controlled via DM_UDEV_*_FLAG variables. >> >> Now, when it comes to the 60-ceph-partuuid-workaround.rules, >> why do we need that at all? I mean, the 60-persistent-storage.rules >> do not whitelist DM devices, so these rules are skipped anyway >> and it was that way since beginning, I think. Now, I see this >> comment in the 60-ceph-partuuid-workaround.rules: >> >> # this is a kludge installed by ceph to fix the /dev/disk/by-partuuid >> # symlinks on systems with old udev (< 180). it's a stripped down >> # version of a newer 60-persistent-storage.rules file that hopefully >> # captures the same set of conditions for setting up those symlinks. >> >> So I need to get to the bottom of the problem which was >> resolved here. Feel free to point me to someone else if you're >> not the right person, but I need to understand what's behind >> these extra workaround rules so I can help to make it work >> correctly with DM devices. > > We added them back when to make the by-partuuid symlinks appear on wheezy: > > commit d8d7113c35b59902902d487738888567e3a6b933 > Author: Sage Weil <sage@xxxxxxxxxxx> > Date: Thu May 16 18:40:29 2013 -0700 > > udev: install disk/by-partuuid rules > > Wheezy's udev (175-7.2) has broken rules for the /dev/disk/by-partuuid/ > symlinks that ceph-disk relies on. Install parallel rules that work. On > new udev, this is harmless; old older udev, this will make life better. > > Fixes: #4865 > Backport: cuttlefish > Signed-off-by: Sage Weil <sage@xxxxxxxxxxx> > > On current master, we are not support wheezy (or rhel6) so we should just > remove this rule file entirely--it is no longer needed for > internfalis, jewel, or later. > > If you're concerned about hammer, then we need to make sure that it still > works on el6, and I'm guessing that is what Loic was working with when we > disabled dm-* skipping to make multipath work... > > sage I am 80% certain this will be fine on SUSE, but since this file has been included we at SUSE (to my surprise as I thought we only needed it on SLE11 and earlier) do need to test the impact. Best wishes Owen -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
