This removes "qemu-io> " prompt from qemu-io output in _filter_qemu_io,
and updates all the output files with the following command:

 cd tests/qemu-iotests && sed -i "s/qemu-io> //g" *.out
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Test 038 uses asynchronous I/O, resulting (potentially) in a different
output for every run (regarding the order of the I/O accesses). This can
be fixed by simply sorting the I/O access messages, since their order is
irrelevant anyway (for this asynchonous I/O).
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The old code detected an overlapping allocation even when the
allocations didn't actually overlap, but were only adjacent.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

This one is a bit more interesting. The COW operation isn't performed
completely synchronously, and therefore dependencies must be handled
correctly when multiple requests write to the same unallocated cluster.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>