[uml-devel] [REGRESSION] um: ubd: block layer issue (Was: ext3 filesystem corruption in user mode linux)

[richard -r. w. <ric...@gm...>]

Hi Tejun!

Chris Frey ran into some problems with ext3 on UML.
See: http://marc.info/?i=20100924041410.GA18040%20()%20foursquare%20!%20net

I can reproduce this issue with any file system on Linux >= 2.6.31.
There seems to be a serious problem with the block layer on UML.
Under high load any file system gets corrupted.

The regression was most likely introduced with this three changes:
83096ebf1263b2c1ee5e653ba37d993d02e3eb7b (block: convert to pos and
nr_sectors accessors)
f81f2f7c9fee307e371f37424577d46f9eaf8692 (ubd: drop unnecessary
rq->sector manipulation)
4d6c84d91d1a539ebc47d1a36a35e9390ba11fdc (ubd: cleanup completion path)

Maybe only f81f2f7 is the bad one. They depend on each and I don't
know all the internals...

-- 
Cheers,
//richard