Subject: Re: ext4 filesystem corruption with 4.10-rc2 on ppc64le

From: Theodore Ts'o <[email-masked]>
Date: Wed, 4 Jan 2017 10:28:37 -0500

On Wed, Jan 04, 2017 at 11:32:42AM +0530, Chandan Rajendra wrote:
> On Wednesday, January 04, 2017 04:18:08 PM Anton Blanchard wrote:
> > I'm consistently seeing ext4 filesystem corruption using a mainline
> > kernel. It doesn't take much to trigger it - download a ppc64le Ubuntu
> > cloud image, boot it in KVM and run:
> > 
> > sudo apt-get update
> > sudo apt-get dist-upgrade
> > sudo reboot
> > 
> > And it never makes it back up, dying with rather severe filesystem
> > corruption.
> 
> The patch at https://patchwork.kernel.org/patch/9488235/ should fix the
> bug.

It looks like this patch is already queued up on the "for-linus"
branch on the linux-block.git tree.

Chandra, thanks for pointing this out!  I had missed your e-mail from
Christmas day, and it was on my todo list to figure out why I was
seeing lots of 1k block regressions on gce-xfstests post-merge window
that wasn't showing up on the ext4.git tree before I sent my pull
request to Linus.

Jens, could you expedite a pull request to Linus?  This is affecting
ext4 on 1k block file systems on x86/x86_64, so this is not a ppc-only
regression.  

Anton or Chandan, could you do me a favor and verify whether or not
64k block sizes are working for you on ppcle on ext4 by running
xfstests?  Light duty testing works for me but when I stress ext4 with
pagesize==blocksize on ppcle64 via xfstests, it blows up.  I suspect
(but am not sure) it's due to (non-upstream) device driver issues, and
a verification that you can run xfstests on your ppcle64 systems using
standard upstream device drivers would be very helpful, since I don't
have easy console access on the machines I have access to at $WORK.  :-(

And of course, if there are still blocksize==pagesize issues on ext4
on ppc64le, it would be good to know that too.

Many thanks!!
						- Ted

P.S.  And for those people who are doing storage work, let me put in a
plug for "gce-xfstests full".  It's cheap and finds lots of problems
before I and others have to.  And if the $1.50 USD is the problem, let
me know and I'll try to work something out.  :-) :-)