Re: fs: Inode cache scalability V3

[Christoph Hellwig]

On Wed, Oct 13, 2010 at 05:46:09PM -0400, Christoph Hellwig wrote:
> On Wed, Oct 13, 2010 at 11:58:45AM -0400, Christoph Hellwig wrote:
> > 
> > It's 100% reproducible on my kvm VM.  The bug is the assert_spin_locked
> > in redirty_tail.  I really can't find a way how we reach it without
> > d_lock so this really confuses me.
> 
> We are for some reason getting a block device inode that is on the
> dirty list of a bdi that it doesn't point to.  Still trying to figure
> out how exactly that happens.

It's because __blkdev_put reset the bdi on the mapping, and bdev inodes
are still special cased to not use s_bdi unlike everybody else.  So
we keep switch between different bdis that get locked.

I wonder what's a good workaround for that.  Just flushing out all
dirty state of a block device inode on last close would fix, but we'd
still have all the dragons hidden underneath until we finally sort
out the bdi reference mess.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/