{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21",
  "slug": "f2fs-segment-information-table",
  "term": "F2FS Segment Information Table",
  "aliases": [
    "F2FS SIT"
  ],
  "definition": "The F2FS Segment Information Table records segment-level block validity information used in space management and cleaning.",
  "note": "In Linux v6.12, an on-disk SIT entry contains a validity bitmap, a field encoding valid-block count and allocation type, and a segment-age field. A validity bit concerns allocation state, not verification of the block's payload against a checksum. [format612]\n\nThe in-memory seg_entry separately tracks current and checkpoint-valid block counts and maps. These are not interchangeable observations. The in-memory ckpt_valid_map is not always a frozen last-checkpoint image: enabled-checkpoint allocation can set its bits, and SSR excludes positions set in either map. [reuse612] [segment612]",
  "related": [
    "f2fs",
    "f2fs-node-address-table",
    "f2fs-segment-summary-area",
    "f2fs-checkpoint",
    "garbage-collection-host",
    "f2fs-slack-space-recycling"
  ],
  "citations": [
    {
      "id": "format612",
      "title": "Linux v6.12 include/linux/f2fs_fs.h: NAT, SIT and summary entry formats.",
      "url": "https://github.com/torvalds/linux/blob/v6.12/include/linux/f2fs_fs.h",
      "accessed": "2026-10-21"
    },
    {
      "id": "segment612",
      "title": "Linux v6.12 fs/f2fs/segment.h: seg_entry and current/checkpoint validity maps.",
      "url": "https://github.com/torvalds/linux/blob/v6.12/fs/f2fs/segment.h",
      "accessed": "2026-10-21"
    },
    {
      "id": "hesela-f2fs",
      "title": "F2FS: when a successful fsync is not a recovery promise",
      "url": "https://hesela.com/analyses/f2fs-checkpoint-fsync-recovery/#metadata-indirection",
      "accessed": "2026-10-21"
    },
    {
      "id": "reuse612",
      "title": "Linux v6.12 fs/f2fs/segment.c: update_sit_entry, __next_free_blkoff and change_curseg.",
      "url": "https://github.com/torvalds/linux/blob/v6.12/fs/f2fs/segment.c",
      "accessed": "2026-10-21"
    }
  ]
}