On Wed, 2019-03-20 at 10:59 +0100, Johannes Thumshirn wrote:
> First of all, have you tried a more recent kernel than the Debian
> kernels you referenced? E.g. Linus' current master or David's misc-
> next
> branch? Just so we don't try to hunt down a bug that's already fixed.
I haven't and that's a bit difficult for me unless it's packaged by the
distro (policy reasons).
Also giving out the image is a bit problematic as it's huge (8TB).
> Also if you can still reproduce the bug, please activate tracing in
> btrfs and send the trace output.
How would I do that?
In the meantime, I think I can reproduce it with fresh images so could
you try the following:
# truncate --size 1G image
# mkfs.btrfs image
# mount -o compress image /mnt
# cd /mnt
# # create some data e.g.:
# tar xaf /usr/src/linux-source-4.19.tar.xz
# cd
# umount /mnt
# losetup -r -f image
# mount -o compress /dev/loop0 /mnt
# find /mnt -type f -exec filefrag -v {} \;
And there your kernel log will explode ;-)
The culprit seems to be the device itself being read-only i.e.
losetup's -r, respectively blockdev --setro DEVICE which I've used
previously.
If you repeat the above from the losetup point, but with -r ...
everything works fine.
Haven't checked whether -o compress actually makes a difference.
Cheers,
Chris.
