ext4: hook the ext3 migration interface to the EXT4_IOC_SETFLAGS ioctl

This patch hooks the ext3 to ext4 migrate interface to
EXT4_IOC_SETFLAGS ioctl. The userspace interface is via chattr +e.  We
only allow setting extent flags.  Clearing extent flag (migrating from
ext4 to ext3) is not supported.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 9b6ad8f..068adc1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -245,7 +245,7 @@
 #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */
 
 #define EXT4_FL_USER_VISIBLE		0x000BDFFF /* User visible flags */
-#define EXT4_FL_USER_MODIFIABLE		0x000380FF /* User modifiable flags */
+#define EXT4_FL_USER_MODIFIABLE		0x000B80FF /* User modifiable flags */
 
 /*
  * Inode dynamic state flags