{
  "slug": "squashfs",
  "term": "SquashFS",
  "aliases": [
    "Squashfs"
  ],
  "definition": "SquashFS is a Linux read-only filesystem for compact images, supporting compression of file data, inodes and directories.",
  "note": "mksquashfs creates populated images. Fragment blocks can pack file tails; inode and directory metadata are packed separately. Metadata blocks may remain uncompressed when requested or when compression would enlarge them. [squashfs]\n\nA read-only filesystem is not a cryptographic trust decision. For a block-backed image, dm-verity can check accessed blocks against a trusted root hash; successful decompression alone does not authenticate the image. [verity]",
  "status": "shipping",
  "advantages": [
    {
      "text": "Compressed data, packed metadata and fragments support space-conscious read-only image layouts.",
      "citationIds": [
        "squashfs"
      ]
    }
  ],
  "limitations": [
    {
      "text": "The reader must support the image features and compressor; compact layout alone does not establish faster reads.",
      "citationIds": [
        "squashfs"
      ]
    }
  ],
  "related": [
    "erofs",
    "read-only-mount",
    "dm-verity",
    "transparent-compression"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-23",
  "citations": [
    {
      "id": "squashfs",
      "title": "Linux v6.16: Squashfs 4.0, image creation, metadata and fragment design",
      "url": "https://docs.kernel.org/6.16/filesystems/squashfs.html",
      "accessed": "2026-10-23"
    },
    {
      "id": "verity",
      "title": "Linux v6.16: dm-verity trust and on-demand verification",
      "url": "https://docs.kernel.org/6.16/admin-guide/device-mapper/verity.html",
      "accessed": "2026-10-23"
    }
  ],
  "provenance": [
    "Version-pinned documentation review; no image-mount experiment or comparative benchmark."
  ]
}