Re: [Xen-devel] Linux 3.1 domU + ext3 = WARNING: at fs/ext3/inode.c

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Oct 25, 2011 at 04:40:09PM -0400, Christopher S. Aker wrote:
> On Oct 25, 2011, at 4:12 PM, Konrad Rzeszutek Wilk wrote:
> > Oh, so this is 3.1 DomU kernel? And your Dom0 is 2.6.18?
> > 
> > What does the guest show for the disk? As in, is the barrier feature
> > enabled? 
> 
> 2.6.18 dom0 and a 3.1.0 domU produces this on domU boot:
> 
> EXT3-fs (xvda): using internal journal
> Adding 262140k swap on /dev/xvdb.  Priority:-1 extents:1 across:262140k SS
> blkfront: barrier: empty write xvda op failed
> blkfront: xvda: barrier or flush: disabled
> end_request: I/O error, dev xvda, sector 1053048
> end_request: I/O error, dev xvda, sector 1053048
> Buffer I/O error on device xvda, logical block 131631
> lost page write due to I/O error on xvda
> Aborting journal on device xvda.
> EXT3-fs (xvda): error: ext3_journal_start_sb: Detected aborted journal
> EXT3-fs (xvda): error: remounting filesystem read-only
> 
> On my 3.0 based dom0 with a 3.1.0 domU blkfront doesn't complain - and I 
> *think* 3.1 domU may actually work as expected -- initial tests couldn't get 
> it to trace...

OK, that might be very well true as the 3.0 dom0 would export the 
'feature-flush-cache'..

but you said that if you use 3.0 domU with 2.6.18 you do not get the
type of warnings as above?


Also, when the DomU guest starts it should report if it "thinks" it
supports barriers. Something like:

blkbfront: xvda: barrier

Or is this the only message you get from blkfront??

> 
> > .. snip
> >> 
> >> Am I barking up the wrong list?
> > 
> > Not sure.. It depends on what your dom0 version is and what
> > the backend is? blktap or blkback?
> 
> blkback.
> 
> We suspected a dom0/domU incompatibility after doing some research.  
> Hopefully this can get resolved within the guest since we have literally 
> thousands of 2.6.18 dom0s deployed and rebooting everyone is not my idea of a 
> good time :)

> 
> Thanks,
> -Chris
> 
> 
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