ext4: Add EXT4_IOC_MIGRATE ioctl

The below patch add ioctl for migrating ext3 indirect block mapped inode
to ext4 extent mapped inode.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index b609294..213974f 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -243,6 +243,7 @@
 #endif
 #define EXT4_IOC_GETRSVSZ		_IOR('f', 5, long)
 #define EXT4_IOC_SETRSVSZ		_IOW('f', 6, long)
+#define EXT4_IOC_MIGRATE		_IO('f', 7)
 
 /*
  * ioctl commands in 32 bit emulation
@@ -983,6 +984,9 @@
 		       unsigned long);
 extern long ext4_compat_ioctl (struct file *, unsigned int, unsigned long);
 
+/* migrate.c */
+extern int ext4_ext_migrate(struct inode *, struct file *, unsigned int,
+		       unsigned long);
 /* namei.c */
 extern int ext4_orphan_add(handle_t *, struct inode *);
 extern int ext4_orphan_del(handle_t *, struct inode *);