QA output created by 313

### Create the image

Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=SIZE

### Write data to allocate more refcount blocks than the cache can hold

wrote 8347648/8347648 bytes at offset 0
7.961 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

### Create an overlay

Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=SIZE backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT

### Fill the overlay with zeroes

wrote 8347648/8347648 bytes at offset 0
7.961 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

### Commit changes to the base image

Image committed.

### Check the base image

No errors were found on the image.
Image end offset: 8396800
*** done