On Thu, Jul 09, 2020 at 12:35:10PM +0200, mwilck@xxxxxxxx wrote: > From: Martin Wilck <mwilck@xxxxxxxx> > > Hi Christophe, hi Ben, > > This is part II of a larger patch series for multpath-tools I've been preparing. > It contains fixes for a customer issue where the same alias was set for > several maps with different WWIDs in the WWIDs file. > > It's based on the previously submitted part II. > > The full series will also be available here: > https://github.com/mwilck/multipath-tools/tree/ups/submit-2007 > > There are tags in that repo for each part of the series. > This part is tagged "submit-200709-3". With the first two of these patches applied , multipathd fails a real-world situation in different, arguably worse, way than it currently does, and I think it could do better. If user_friendly_names is set, but two (or more) devices weren't in the initramfs bindings file, they will get random aliases during boot. Assuming the devices are in the regular filesystem bindings file, it's not super uncommon for these devices to pick from the same alias as they use in the regular bindings file, but with different wwids matching to different aliases. Without these patches, multipath will rename them if possible, but if not, they will still exist, but with the wrong alias. Existing with the wrong alias isn't great, since things could be checking for the devices by name, which could cause corruption. But in reality, usually they are referenced by Labels, which will still work (since most things are designed to not expect persistent naming of devices). However, with this patches, some of the devices will be deleted, which avoids the possiblity of corruption, but in practice usually is worse because referencing devices by label already avoids the corruption problem. A better idea might simply be to fallback to using the WWID as an alias, on the offending map. This should avoid corruption, since unless someone manually set the WWID as an alias in multipath.conf it should be unique. But it won't cause an existing, and possibly necessary, device to get deleted. -Ben > Regards, > Martin > > Martin Wilck (3): > libmultipath: refuse creating map with duplicate alias > libmultipath: refuse reloading an existing map with different WWID > libmultipath: dm_addmap(): refuse creating map with empty WWID > > libmultipath/configure.c | 24 ++++++++++++++++++++---- > libmultipath/devmapper.c | 26 +++++++++++++++----------- > libmultipath/structs_vec.c | 13 +++++++++++++ > libmultipath/structs_vec.h | 1 + > multipathd/main.c | 6 +++++- > 5 files changed, 54 insertions(+), 16 deletions(-) > > -- > 2.26.2 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
