ext4: reserve xattr index for the Hurd

The Hurd is using inode fields which restricts it from using more
advanced ext4 file system features, due to design choices made over a
decade ago.  By giving the Hurd an extended attribute index field we
allow it to move the translator and author fields out of the core
inode fields, and hopefully we can get rid of ugly hacks such as
EXT4_OS_HURD and EXT4_MOUNT2_HURD_COMPAT somday.

For more information please see:
      https://summerofcode.withgoogle.com/projects/#5869799859027968

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 69dd3e6566e02edd05a4ef8054913df1326bd29a..a92e783fa057070a2d46ece41089bae6e3a26fe4 100644 (file)
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -24,6 +24,7 @@
 #define EXT4_XATTR_INDEX_SYSTEM                        7
 #define EXT4_XATTR_INDEX_RICHACL               8
 #define EXT4_XATTR_INDEX_ENCRYPTION            9
+#define EXT4_XATTR_INDEX_HURD                  10 /* Reserved for Hurd */
 
 struct ext4_xattr_header {
        __le32  h_magic;        /* magic number for identification */