Re: Problems with hfsplus on ipods in 2.6.38+

[Seth Forshee <seth.forshee@canonical.com>]

On Fri, Jul 15, 2011 at 11:43:47AM -0400, Daniel Barkalow wrote:
> On Fri, 15 Jul 2011, Seth Forshee wrote:
> 
> > On Thu, Jul 14, 2011 at 09:26:11PM -0400, Daniel Barkalow wrote:
> > > Okay, I've applied that patch set, and it worked for me without any issues 
> > > thus far. If you're interested in the debugging output from a device that 
> > > doesn't work with vanilla but doesn't oops or panic with that patch set, 
> > > it's attached. I'm using 32-bit x86, if that helps for tracking down 
> > > differences.
> > 
> > Hrm, looks like I used %lu for sector_t instead of %llu, and that's
> > messing up the output on 32-bit builds. What I am able to see looks
> > correct though. I put up a new version of the patches with the output
> > fixed along with a new build on the bug.
> > 
> > I've had some success producing problems using scsi_debug with a 64-bit
> > build, specifically with 1K or 2K sectors. Actually a lot of odd things
> > happen with those sector sizes, and they happen whether using my patch
> > or reverting the two patches that change hfsplus to using bio, so those
> > problems seem unrelated. What I see is that the free/used space numbers
> > reported by df don't make sense given the actual files I've copied to
> > the volume. If I "fill" the volume (in quotes because really I haven't
> > copied in enough data to fill the volume, but it says it's full anyway)
> > df reports complete garbage. Then if I proceed to remove all files from
> > the volume df still reports that 50% of the space is used. These
> > problems aren't present with 512 byte or 4K sectors.
> > 
> > What I also see are GPFs in memory allocation code, which is what I
> > believe others have seen with my patch, and so far I haven't seen those
> > with the reversions. So I'm suspecting memory corruption, but I don't
> > yet see where the corruption is coming form. I found one problem, but I
> > don't suspect it's responsible for the GPFs.
> 
> A while later, somewhat after I'd unmounted the filesystem (and sent the 
> email), I got some memory allocation oopses, also, followed eventually by 
> some sort of hang (userspace not working but alt-sysrq did work). So I 
> agree with the memory corruption idea. Do you want corrected debugging 
> output, or any other information from my actual device, or are you set 
> with scsi_debug for now?

I think I'm okay with scsi_debug. What would be most helpful now is a
deterministic way to reproduce the oopses.