[PATCH] ext4: enable building of ext4

Originally part of a patch from Mingming Cao and Randy Dunlap.  Reorganized
by Shaggy.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Mingming Cao<cmm@us.ibm.com>
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/Kconfig

@@ -140,6 +140,73 @@ config EXT3_FS_SECURITY
 	  If you are not using a security module that requires using
 	  extended attributes for file security labels, say N.
 
+config EXT4DEV_FS
+	tristate "Ext4dev/ext4 extended fs support development (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+        select JBD
+        help
+	  Ext4dev is a predecessor filesystem of the next generation
+	  extended fs ext4, based on ext3 filesystem code. It will be
+	  renamed ext4 fs later, once ext4dev is mature and stabilized.
+
+          Unlike the change from ext2 filesystem to ext3 filesystem,
+          the on-disk format of ext4dev is not the same as ext3 any more:
+	  it is based on extent maps and it supports 48-bit physical block
+          numbers. These combined on-disk format changes will allow
+	  ext4dev/ext4 to handle more than 16 TB filesystem volumes --
+	  a hard limit that ext3 cannot overcome without changing the
+          on-disk format.
+
+	  Other than extent maps and 48-bit block numbers, ext4dev also is
+          likely to have other new features such as persistent preallocation,
+	  high resolution time stamps, and larger file support etc.  These
+          features will be added to ext4dev gradually.
+
+	  To compile this file system support as a module, choose M here. The
+	  module will be called ext4dev.  Be aware, however, that the filesystem
+	  of your root partition (the one containing the directory /) cannot
+	  be compiled as a module, and so this could be dangerous.
+
+	  If unsure, say N.
+
+config EXT4DEV_FS_XATTR
+	bool "Ext4dev extended attributes"
+	depends on EXT4DEV_FS
+	default y
+	help
+	  Extended attributes are name:value pairs associated with inodes by
+	  the kernel or by users (see the attr(5) manual page, or visit
+	  <http://acl.bestbits.at/> for details).
+
+	  If unsure, say N.
+
+	  You need this for POSIX ACL support on ext4dev/ext4.
+
+config EXT4DEV_FS_POSIX_ACL
+	bool "Ext4dev POSIX Access Control Lists"
+	depends on EXT4DEV_FS_XATTR
+	select FS_POSIX_ACL
+	help
+	  POSIX Access Control Lists (ACLs) support permissions for users and
+	  groups beyond the owner/group/world scheme.
+
+	  To learn more about Access Control Lists, visit the POSIX ACLs for
+	  Linux website <http://acl.bestbits.at/>.
+
+	  If you don't know what Access Control Lists are, say N
+
+config EXT4DEV_FS_SECURITY
+	bool "Ext4dev Security Labels"
+	depends on EXT4DEV_FS_XATTR
+	help
+	  Security labels support alternative access control models
+	  implemented by security modules like SELinux.  This option
+	  enables an extended attribute handler for file security
+	  labels in the ext4dev/ext4 filesystem.
+
+	  If you are not using a security module that requires using
+	  extended attributes for file security labels, say N.
+
 config JBD
 	tristate
 	help
@@ -173,11 +240,11 @@ config JBD_DEBUG
 	  "echo 0 > /proc/sys/fs/jbd-debug".
 
 config FS_MBCACHE
-# Meta block cache for Extended Attributes (ext2/ext3)
+# Meta block cache for Extended Attributes (ext2/ext3/ext4)
 	tristate
-	depends on EXT2_FS_XATTR || EXT3_FS_XATTR
+	depends on EXT2_FS_XATTR || EXT3_FS_XATTR || EXT4DEV_FS_XATTR
-	default y if EXT2_FS=y || EXT3_FS=y
+	default y if EXT2_FS=y || EXT3_FS=y || EXT4DEV_FS=y
-	default m if EXT2_FS=m || EXT3_FS=m
+	default m if EXT2_FS=m || EXT3_FS=m || EXT4DEV_FS=m
 
 config REISERFS_FS
 	tristate "Reiserfs support"

fs/Makefile

@@ -62,6 +62,7 @@ obj-$(CONFIG_DLM)		+= dlm/
 # Do not add any filesystems before this line
 obj-$(CONFIG_REISERFS_FS)	+= reiserfs/
 obj-$(CONFIG_EXT3_FS)		+= ext3/ # Before ext2 so root fs can be ext3
+obj-$(CONFIG_EXT4DEV_FS)	+= ext4/ # Before ext2 so root fs can be ext4dev
 obj-$(CONFIG_JBD)		+= jbd/
 obj-$(CONFIG_EXT2_FS)		+= ext2/
 obj-$(CONFIG_CRAMFS)		+= cramfs/

include/linux/magic.h

@@ -8,6 +8,7 @@
 #define EFS_SUPER_MAGIC		0x414A53
 #define EXT2_SUPER_MAGIC	0xEF53
 #define EXT3_SUPER_MAGIC	0xEF53
+#define EXT4_SUPER_MAGIC	0xEF53
 #define HPFS_SUPER_MAGIC	0xf995e849
 #define ISOFS_SUPER_MAGIC	0x9660
 #define JFFS2_SUPER_MAGIC	0x72b6