18c2ecf20Sopenharmony_ci# SPDX-License-Identifier: GPL-2.0-only 28c2ecf20Sopenharmony_ciconfig NILFS2_FS 38c2ecf20Sopenharmony_ci tristate "NILFS2 file system support" 48c2ecf20Sopenharmony_ci select CRC32 58c2ecf20Sopenharmony_ci help 68c2ecf20Sopenharmony_ci NILFS2 is a log-structured file system (LFS) supporting continuous 78c2ecf20Sopenharmony_ci snapshotting. In addition to versioning capability of the entire 88c2ecf20Sopenharmony_ci file system, users can even restore files mistakenly overwritten or 98c2ecf20Sopenharmony_ci destroyed just a few seconds ago. Since this file system can keep 108c2ecf20Sopenharmony_ci consistency like conventional LFS, it achieves quick recovery after 118c2ecf20Sopenharmony_ci system crashes. 128c2ecf20Sopenharmony_ci 138c2ecf20Sopenharmony_ci NILFS2 creates a number of checkpoints every few seconds or per 148c2ecf20Sopenharmony_ci synchronous write basis (unless there is no change). Users can 158c2ecf20Sopenharmony_ci select significant versions among continuously created checkpoints, 168c2ecf20Sopenharmony_ci and can change them into snapshots which will be preserved for long 178c2ecf20Sopenharmony_ci periods until they are changed back to checkpoints. Each 188c2ecf20Sopenharmony_ci snapshot is mountable as a read-only file system concurrently with 198c2ecf20Sopenharmony_ci its writable mount, and this feature is convenient for online backup. 208c2ecf20Sopenharmony_ci 218c2ecf20Sopenharmony_ci Some features including atime, extended attributes, and POSIX ACLs, 228c2ecf20Sopenharmony_ci are not supported yet. 238c2ecf20Sopenharmony_ci 248c2ecf20Sopenharmony_ci To compile this file system support as a module, choose M here: the 258c2ecf20Sopenharmony_ci module will be called nilfs2. If unsure, say N. 26