On Tue, Mar 03, 2009 at 08:36:10PM +0100, Jan Kara wrote:

  Hi,

quoted

Unresolved regressions
----------------------

Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=12551
Subject		: end_request: I/O error, dev cciss/c0d0, sector 87435720
Submitter	: Ralf Hildebrandt [off-list ref]
Date		: 2009-01-27 06:51 (28 days old)

Bug-Entry	: http://bugzilla.kernel.org/show_bug.cgi?id=12497
Subject		: new barrier warnings in 2.6.29-rc1
Submitter	: Christoph Hellwig [off-list ref]
Date		: 2009-01-12 15:46 (43 days old)
References	: http://marc.info/?l=linux-kernel&m=123177528217154&w=4
Handled-By	: Jens Axboe [off-list ref]

  I've just noticed that the above two reports are probably the same bug...
Just that we don't duplicate the effort.

At least on the XFS side it's fixed now.  The block layer gets the
initial detection right without warning, and a patch to fix the
unconditional cache flush on unmount is on it's way.