f2fs-segment-summary-area · shipping · also F2FS SSA

F2FS Segment Summary Area

The F2FS Segment Summary Area stores ownership information for blocks in the filesystem's main area.

The Linux v6.12 summary format uses the direct-node ID for a data block and the node's own ID for a node block. Data summaries also identify the offset of the data-block address within its node; the entry interpretation depends on the block type. [1]

This ownership direction differs from NAT's node-ID-to-location lookup and SIT's validity bookkeeping. These structures answer different questions during cleaning; none is a backup of the user payload. [2]

Relations

related
F2FS, F2FS Node Address Table, F2FS Segment Information Table, Host-side flash GC

Citations

  1. Linux v6.12 include/linux/f2fs_fs.h: NAT, SIT and summary entry formats. (accessed 2026-10-21)
  2. Linux 6.12 F2FS documentation: wandering tree, on-disk layout and metadata structure. (accessed 2026-10-21)

Further reading

  1. F2FS: when a successful fsync is not a recovery promise (accessed 2026-10-21)

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Hesela team. F2FS Segment Summary Area. Hesela. 2026-10-21. https://hesela.dev/terms/f2fs-segment-summary-area/