QA output created by 280
wrote 134217728/134217728 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

File foo fiemap before COWing extent:

0: [0..261887]: shared|encoded
1: [261888..262143]: shared|encoded|last

Overwriting file range [120M, 120M + 128K) in the snapshot

wrote 131072/131072 bytes at offset 125829120
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

File foo fiemap after COWing extent in the snapshot:

0: [0..245759]: shared|encoded
1: [245760..246015]: encoded
2: [246016..261887]: shared|encoded
3: [261888..262143]: shared|encoded|last