xfstests: 301: sparse copy between different filesystems/mountpoints on btrfs

[Dave Chinner]

On Sat, Mar 09, 2013 at 06:24:47PM -0600, Eric Sandeen wrote:
> On 1/18/13 3:48 PM, Koen De Wit wrote:
> > +}
> > +
> > +_scratch_mount
> > +_create_reflinks_to $TESTDIR2
> > +_scratch_unmount
> > +
> > +mount $TEST_DEV $SCRATCH_MNT
> > +_create_reflinks_to $TESTDIR3
> > +umount $SCRATCH_MNT
> 
> TBH this confuses me, not that it's necessarily wrong (?)
> You mount TEST_DEV on $SCRATCH_MNT which makes my brain hurt a little.
> Then _create_reflinks_to $TESTDIR3 and at that point, um, what's going on,
> what's linking what to where?

Mounting the TEST_DEV on SCRATCH_MNT is almost always a bad thing to
do. The test harness expects TEST_DEV to be mounted on TEST_DIR, not
anywhere else.

If you need multiple scratch filesystems to test cross-device
linkage errors, use loopback devices or make use of the btrfs
scratch device pool...

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com