iotests: New test 223 for exporting dirty bitmap over NBD

Although this test is NOT a full test of image fleecing (as it
intentionally uses just a single block device directly exported
over NBD, rather than trying to set up a blockdev-backup job with
multiple BDS involved), it DOES prove that qemu as a server is
able to properly expose a dirty bitmap over NBD.

When coupled with image fleecing, it is then possible for a
third-party client to do an incremental backup by using
qemu-img map with the x-dirty-bitmap option to learn which parts
of the file are dirty (perhaps confusingly, they are the portions
mapped as "data":false - which is part of the reason this is
still in the x- experimental namespace), along with another
normal client (perhaps 'qemu-nbd -c' to expose the server over
/dev/nbd0 and then just use normal I/O on that block device) to
read the dirty sections.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180702191458.28741-3-eblake@redhat.com>
Tested-by: John Snow <jsnow@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>

1 files changed, 49 insertions, 0 deletions

diff --git a/tests/qemu-iotests/223.out b/tests/qemu-iotests/223.out
new file mode 100644
index 0000000000..33021c8e6a
--- /dev/null
+++ b/tests/qemu-iotests/223.out
@@ -0,0 +1,49 @@
+QA output created by 223
+
+=== Create partially sparse image, then add dirty bitmap ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4194304
+wrote 2097152/2097152 bytes at offset 1048576
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Testing:
+QMP_VERSION
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "SHUTDOWN", "data": {"guest": false}}
+
+
+=== Write part of the file under active bitmap ===
+
+wrote 2097152/2097152 bytes at offset 2097152
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+=== End dirty bitmap, and start serving image over NBD ===
+
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+{"return": {}}
+
+=== Contrast normal status with dirty-bitmap status ===
+
+read 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1048576/1048576 bytes at offset 1048576
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2097152/2097152 bytes at offset 2097152
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+[{ "start": 0, "length": 1048576, "depth": 0, "zero": true, "data": false},
+{ "start": 1048576, "length": 3145728, "depth": 0, "zero": false, "data": true}]
+[{ "start": 0, "length": 2097152, "depth": 0, "zero": false, "data": true},
+{ "start": 2097152, "length": 2097152, "depth": 0, "zero": false, "data": false}]
+
+=== End NBD server ===
+
+{"return": {}}
+{"return": {}}
+{"return": {}}
+*** done