1*4882a593Smuzhiyun# SPDX-License-Identifier: GPL-2.0-only 2*4882a593Smuzhiyunconfig NILFS2_FS 3*4882a593Smuzhiyun tristate "NILFS2 file system support" 4*4882a593Smuzhiyun select CRC32 5*4882a593Smuzhiyun help 6*4882a593Smuzhiyun NILFS2 is a log-structured file system (LFS) supporting continuous 7*4882a593Smuzhiyun snapshotting. In addition to versioning capability of the entire 8*4882a593Smuzhiyun file system, users can even restore files mistakenly overwritten or 9*4882a593Smuzhiyun destroyed just a few seconds ago. Since this file system can keep 10*4882a593Smuzhiyun consistency like conventional LFS, it achieves quick recovery after 11*4882a593Smuzhiyun system crashes. 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun NILFS2 creates a number of checkpoints every few seconds or per 14*4882a593Smuzhiyun synchronous write basis (unless there is no change). Users can 15*4882a593Smuzhiyun select significant versions among continuously created checkpoints, 16*4882a593Smuzhiyun and can change them into snapshots which will be preserved for long 17*4882a593Smuzhiyun periods until they are changed back to checkpoints. Each 18*4882a593Smuzhiyun snapshot is mountable as a read-only file system concurrently with 19*4882a593Smuzhiyun its writable mount, and this feature is convenient for online backup. 20*4882a593Smuzhiyun 21*4882a593Smuzhiyun Some features including atime, extended attributes, and POSIX ACLs, 22*4882a593Smuzhiyun are not supported yet. 23*4882a593Smuzhiyun 24*4882a593Smuzhiyun To compile this file system support as a module, choose M here: the 25*4882a593Smuzhiyun module will be called nilfs2. If unsure, say N. 26