ext2fs crash in -current (r218056)

John Baldwin jhb at freebsd.org
Thu Feb 3 13:57:08 UTC 2011

On Wednesday, February 02, 2011 5:20:23 pm Jeremy Chadwick wrote:
> On Wed, Feb 02, 2011 at 05:04:03PM -0500, John Baldwin wrote:
> > On Wednesday, February 02, 2011 04:13:48 pm Doug Barton wrote:
> > > I haven't had a chance to test this patch yet, but John's did not work
> > > (sorry):
> > > 
> > > http://dougbarton.us/ext2fs-crash-dump-2.jpg
> > > 
> > > No actual dump this time either.
> > > 
> > > I'm happy to test the patch below on Thursday if there is consensus that
> > > it will work.
> > 
> > Err, this is a different panic than what you reported earlier.  Your disk died 
> > and spewed a bunch of EIO errors.  I can look at the locking assertion failure 
> > tomorrow, but this is a differnt issue.  Even UFS needed a good bit of work to 
> > handle disks dying gracefully.
> Are the byte offsets shown in the screenshot within the range of the
> drive's capacity?  They're around the 10.7GB mark, but I have no idea
> what size disk is being used.
> The reason I ask is that there have been reported issues in the past
> where the offsets shown are way outside of the range of the permitted
> byte offsets of the disk itself (and in some cases even showing a
> negative number; what is it with people not understanding the difference
> between signed and unsigned types?  Sigh), and I want to make sure this
> isn't one of those situations.  I also don't know if underlying
> filesystem corruption could cause the problem in question ("filesystem
> says you should write to block N, which is outside of the permitted
> range of the device").

Just one comment.  UFS uses negative block numbers to indicate an indirect
block (or some such) as opposed to a direct block of data.  It's a purposeful
feature that allows one to instantly spot if a problem relates to a direct
block vs an indirect block.

John Baldwin

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