nilfs2: update makefile and Kconfig

This adds a Makefile for the nilfs2 file system, and updates the
makefile and Kconfig file in the file system directory.

Signed-off-by: Ryusuke Konishi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/Kconfig

@@ -175,9 +175,34 @@ source "fs/qnx4/Kconfig"
 source "fs/romfs/Kconfig"
 source "fs/sysv/Kconfig"
 source "fs/ufs/Kconfig"
-
 source "fs/exofs/Kconfig"
 
+config NILFS2_FS
+	tristate "NILFS2 file system support (EXPERIMENTAL)"
+	depends on BLOCK && EXPERIMENTAL
+	select CRC32
+	help
+	  NILFS2 is a log-structured file system (LFS) supporting continuous
+	  snapshotting.  In addition to versioning capability of the entire
+	  file system, users can even restore files mistakenly overwritten or
+	  destroyed just a few seconds ago.  Since this file system can keep
+	  consistency like conventional LFS, it achieves quick recovery after
+	  system crashes.
+
+	  NILFS2 creates a number of checkpoints every few seconds or per
+	  synchronous write basis (unless there is no change).  Users can
+	  select significant versions among continuously created checkpoints,
+	  and can change them into snapshots which will be preserved for long
+	  periods until they are changed back to checkpoints.  Each
+	  snapshot is mountable as a read-only file system concurrently with
+	  its writable mount, and this feature is convenient for online backup.
+
+	  Some features including atime, extended attributes, and POSIX ACLs,
+	  are not supported yet.
+
+	  To compile this file system support as a module, choose M here: the
+	  module will be called nilfs2.  If unsure, say N.
+
 endif # MISC_FILESYSTEMS
 
 menuconfig NETWORK_FILESYSTEMS