On Fri, Jan 08 2010 at 1:41pm -0500, Martin K. Petersen <martin.petersen@xxxxxxxxxx> wrote: > >>>>> "Mike" == Mike Snitzer <snitzer@xxxxxxxxxx> writes: > > Mike, > > Mike> Seems I took the time to add a comment whose FIXME doesn't ring > Mike> many bells now! But ignoring that, the comment before the FIXME > Mike> is making a veiled reference to userspace having consumed > Mike> alignment_offset. > > I read and understood the comment. But even then explicitly zeroing out > those two values didn't make sense (because if user space did in fact do > the right thing they'd always be zero). > > I know that the DM utilities take care of business. And that DM devices > are special because they are always set up by user space and not a > kernel discovery process. > > But since the code *is* in place to validate things I'm not so keen on > you clearing fields that have been calculated and have a meaning. For > me it masked a case where the DM utilities did the wrong thing (because > they were old). > > With the Enterprise Linux hat on it is easy for us to specify that you > must use this version of the kernel and the device mapper utilities. > But reality is that lots of people are running upstream kernels on > distributions with older userland. And some distributions get things > wrong, ship broken bits, etc. > > It's great that new DM utils will transparently adjust the starting > offset. That's the way it's supposed to work. No arguments there. > > My main concern is making sure that we never get into a case where we > run with misaligned components without indicating that there is a > problem. Ever! Regardless of which DM utils might be in place. > > We have the power to get that right. All the pieces are in place. I'd > simply like us to stop making assumptions about user space always doing > the right thing. Yeap, I already agreed that those 2 lines should be removed (in the p.s. of my previous mail). They really aren't serving any purpose and their justification was/is tenuous at best. I'll get the fix, for 2.6.33, to Alasdair shortly. Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
