image: ext4-deep-extents.img
features: extent,64bit,flex_bg,metadata_csum
volume_label: deep-vol
contents:
  /sparse.bin  — 16 MB sparse file with single 'X' bytes every 64 KB
                 (~245 extents — forces multi-level extent tree)
  /dense.txt   — "control file\n" (13 bytes, single inline extent)
test_targets:
  - extent::lookup must descend through internal nodes for high logical blocks
  - sparse holes should read as zero
