162306a36Sopenharmony_ci# SPDX-License-Identifier: GPL-2.0-only 262306a36Sopenharmony_ciconfig NILFS2_FS 362306a36Sopenharmony_ci tristate "NILFS2 file system support" 462306a36Sopenharmony_ci select BUFFER_HEAD 562306a36Sopenharmony_ci select CRC32 662306a36Sopenharmony_ci select LEGACY_DIRECT_IO 762306a36Sopenharmony_ci help 862306a36Sopenharmony_ci NILFS2 is a log-structured file system (LFS) supporting continuous 962306a36Sopenharmony_ci snapshotting. In addition to versioning capability of the entire 1062306a36Sopenharmony_ci file system, users can even restore files mistakenly overwritten or 1162306a36Sopenharmony_ci destroyed just a few seconds ago. Since this file system can keep 1262306a36Sopenharmony_ci consistency like conventional LFS, it achieves quick recovery after 1362306a36Sopenharmony_ci system crashes. 1462306a36Sopenharmony_ci 1562306a36Sopenharmony_ci NILFS2 creates a number of checkpoints every few seconds or per 1662306a36Sopenharmony_ci synchronous write basis (unless there is no change). Users can 1762306a36Sopenharmony_ci select significant versions among continuously created checkpoints, 1862306a36Sopenharmony_ci and can change them into snapshots which will be preserved for long 1962306a36Sopenharmony_ci periods until they are changed back to checkpoints. Each 2062306a36Sopenharmony_ci snapshot is mountable as a read-only file system concurrently with 2162306a36Sopenharmony_ci its writable mount, and this feature is convenient for online backup. 2262306a36Sopenharmony_ci 2362306a36Sopenharmony_ci Some features including atime, extended attributes, and POSIX ACLs, 2462306a36Sopenharmony_ci are not supported yet. 2562306a36Sopenharmony_ci 2662306a36Sopenharmony_ci To compile this file system support as a module, choose M here: the 2762306a36Sopenharmony_ci module will be called nilfs2. If unsure, say N. 28