nilfs2: move ioctl interface and disk layout to uapi separately

The header file "include/linux/nilfs2_fs.h" is composed of parts for
ioctl and disk format, and both are intended to be shared with user
space programs.

This moves them to the uapi directory "include/uapi/linux" splitting the
file to "nilfs2_api.h" and "nilfs2_ondisk.h".  The following minor
changes are accompanied by this migration:

 - nilfs_direct_node struct in nilfs2/direct.h is converged to
   nilfs2_ondisk.h because it's an on-disk structure.
 - inline functions nilfs_rec_len_from_disk() and
   nilfs_rec_len_to_disk() are moved to nilfs2/dir.c.

Link: http://lkml.kernel.org/r/1465825507-3407-4-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index 56af5e4..81c7f2b 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -248,7 +248,7 @@
 'm'	00	drivers/scsi/megaraid/megaraid_ioctl.h	conflict!
 'm'	00-1F	net/irda/irmod.h	conflict!
 'n'	00-7F	linux/ncp_fs.h and fs/ncpfs/ioctl.c
-'n'	80-8F	linux/nilfs2_fs.h	NILFS2
+'n'	80-8F	uapi/linux/nilfs2_api.h	NILFS2
 'n'	E0-FF	linux/matroxfb.h	matroxfb
 'o'	00-1F	fs/ocfs2/ocfs2_fs.h	OCFS2
 'o'     00-03   mtd/ubi-user.h		conflict! (OCFS2 and UBI overlaps)