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    SubjectRe: [GIT PULL] ext4 updates for 3.11
    Date
    On 2013/03/07 12:12 PM, "Greg KH" <greg@kroah.com> wrote:

    >On Wed, Jul 03, 2013 at 01:29:41PM +1000, Dave Chinner wrote:
    >> On Tue, Jul 02, 2013 at 06:01:11PM -0700, Greg KH wrote:
    >> > On Tue, Jul 02, 2013 at 05:58:15PM -0700, Linus Torvalds wrote:
    >> > > On Tue, Jul 2, 2013 at 5:54 PM, Greg KH <greg@kroah.com> wrote:
    >> > > > On Tue, Jul 02, 2013 at 05:02:21PM -0700, Linus Torvalds wrote:
    >> > > >>
    >> > > >> I'm really not convinced this whole Lustre thing was correctly
    >> > > >> handled. Merging it into stable and yet being in such bad shape
    >>that
    >> > > >> it isn't enabled even there? I just dunno. But I have the turd
    >>in my
    >> > > >> tree now, let's hope it gets fixed up.
    >> > > >
    >> > > > It's in "staging", not "stable" :)
    >> > >
    >> > > Yes. But what was the reason to actually merge it even there? And
    >>once
    >> > > it gets merged, disabling it again rather than fixing the problems
    >>it
    >> > > has?
    >> >
    >> > The problems turned out to be too big, too late in the merge cycle for
    >> > me to be able to take them (they still aren't even done, as I don't
    >>have
    >> > a working set of patches yet.) So I just disabled it from the build
    >>to
    >> > give Andreas and team time to get it working properly.

    In our defence, the code has been working fine for years, but only on
    vendor
    kernels, so we are playing catch-up to the mainline kernel, and hit a
    bunch of
    snags when merging into -next.

    Also, all of the configure checks have been removed from the version
    submitted
    to the kernel, so this caused some breakage on platforms that Lustre
    actually
    runs on regularly (e.g. PPC). On the flip side, nobody ever uses Lustre
    on S390
    or 32-bit clients, so it is no surprise that there were problems there.

    >> > I could have just removed it, but I thought I would give them a
    >>chance.

    Thanks. The code is just too big to get it ready for inclusion in one
    piece,
    and the only way that we can make it acceptable for mainline kernel
    inclusion
    is through -staging and incrementally cleaning it up.

    >> > > This is a filesystem that Intel apparently wants to push. I think it
    >> > > would have been a better idea to push back a bit and say "at least
    >> > > clean it up a bit first". It's not like Intel is one of the clueless
    >> > > companies that couldn't have done so and need help from the
    >>community.

    Well, it's been around for 10 years, and is pretty much the standard
    filesystem
    in HPC. While we are part of Intel now, there is still only a limited
    number of
    people working on it, and we don't have free reign to focus on getting it
    into
    the kernel. We still have customers to support and bugs to fix and
    features to
    develop for the next huge systems (1B cores writing 300TB/s to 1EB fs in
    2018).
    At the same time, there is enough demand in the
    workgroup/department/university
    scale that it makes sense to try and get it into mainline.

    It isn't that we didn't want to get it into the kernel previously, but
    -staging
    didn't always exist and we don't have enough resources at one time to
    rewrite
    all of the code. Thanks to Peng Tao and EMC this is finally happening.
    This
    isn't "volunteer community" effort, there are dedicated resources working
    on it.

    >> > For this filesystem, it seems that they don't have any resources to do
    >> > this work and are relying on the community to help out. Which is odd,
    >> > but big companies are strange some times...
    >>
    >> Didn't we learn this lesson already with POHMELFS? i.e. that dumping
    >> filesystem code in staging on the assumption "the community" will
    >> fix it up when nobody in "the community" uses or can even test that
    >> filesystem is a broken development model....
    >
    >They (Intel) has said that they will continue to clean up this code in
    >the tree, until it is in good enough shape to be merged into fs/
    >properly. If they ever stop helping out, I will end up dropping it from
    >the tree, just like I did for pohmelfs, so don't worry about it
    >lingering around abandoned.

    Right, we are going to continue working on cleaning the code at a steady
    pace
    until it is ready to move to fs/. I don't expect Al or Dave or Christoph
    to
    spend their time (or make their eyes bleed) with the current state of the
    code.
    It has already undergone some significant cleanup, but needs a bunch more
    still.

    To be honest, I expect it will be in -staging for a year or so, but that is
    fine with me since we've been working on it for 10+ years already and we
    only
    have so much capacity for changing/testing the code for the kernel while
    keeping
    all of the existing sites in working condition.

    Cheers, Andreas
    --
    Andreas Dilger

    Lustre Software Architect
    Intel High Performance Data Division




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