[linux-lvm] Re: LVM 2.2 snapshot bug

Andrea Arcangeli andrea at suse.de
Tue Nov 7 16:45:04 UTC 2000

On Tue, Nov 07, 2000 at 03:56:59PM +0100, Rik van Riel wrote:
> That's a bit much to type in by hand ... and it's basically
> kjournald being confused by all its writes failing on a RW
> block device.

So ext3 will crash also if I/O errors happen during the log reply.  The Oopses
seems due an _ext3_ bug (not due the missing ro_bits in the LVM snapshot)
as far I can tell.

> Indeed this is the case. When the block device is read-write
> (the is_read_only(blk_dev) is non-true) it tries to replay
> the log, even for a read-only mounted FS.

Ok, I agree it's a minor LVM bug, but again I can't see how that minor bug can
cause oopses and I think setting ro_bits won't fix the real bug but it will
only hide it.

BTW, LVM also internally checks for the LV_WRITE bitflag during open(2) so any
attempt to open the snapshot RW will fail return -EACCESS as expected.

> It's with the LVM from the Conectiva kernel RPM, which
> uses the source code from your 2.2 LVM driver.


I will fix the is_read_only thing for the snapshot but you should make sure the
bug that is oopsing your machine gets fixed too :).


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