file-extent · shipping · also filesystem extent

File extent

A filesystem mapping for a contiguous range of file blocks and the storage blocks backing that range.

Ext4 stores a starting file block, storage block and length for each extent, reducing mapping metadata for contiguous runs; this is a filesystem representation, not a statement about physical NAND placement.

Relations

related

unwritten-extent, sparse-file, file-preallocation, reflink

Citations

1. Linux 6.12: ext4 extent tree and mapping format (accessed 2026-10-13)
2. Sparse files, preallocation and thin-pool capacity (accessed 2026-10-13)

JSON: /data/terms/file-extent.json