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Re: LVM 0.9.1beta7 and ext3 0.0.6b



Jay writes:
> I've recently been playing about with recent ext3 0.0.6b and lvm 0.9.1
> beta7 and am now able to trigger an "Attempt to refile free buffer"
> assertion.
> 
> This seems to "only" occur when using ext3 on the root filesystem.
> Possibly that is related to the fact that the lvm utility I'm using to
> reproduce this problem is modifying data in /etc.

Yes, I had this same problem with LVM 0.9.1b7 and ext3 0.0.6b.

> The easist reproduction case I've come across to generate the assertion is
> to load up lvm (insmod if necessary) and then run:
> 
> 	while /bin/true; do vgscan -v; done

The same is true even if you only do pvscan (this has no chance to blow
up your LVM configuration).  The reason is because of LVM calling
invalidate_buffers on all of the devices (I believe), but I haven't tracked
down all of the reasons it is happening.  In __invalidate_buffers, Stephen
asked to add in "&& bh->b_jlist == BJ_None" to the checks for put_last_free(),
but this only reduced the assertions and did not remove them entirely.

> Again, it doesn't seem to generate the problem when using ext2 on the root
> filesystem even if I have ext3 in use on seperate filesystems.  Also, you
> do not need to have an LVM device actively mounted to generate this.  In
> my case I have no active lvm devices up and running, just lvm-mod
> insmoded.

This is more than what I figured out.  Initially, I thought it had to do
with the LVM devices themselves (on which I was running ext3), but after
putting in debugging I also see that the buffers belong to the root device.
In my case, I have data journaling on root.  Is this the case for you?

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert





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