magic.h: move some FS magic numbers into magic.h

- Move open-coded filesystem magic numbers into magic.h

- Rearrange magic.h so that the filesystem-related constants are grouped
  together.

Signed-off-by: Muthukumar R <muthur@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/block_dev.c b/fs/block_dev.c
index a9ff300..e08f6a20 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -16,6 +16,7 @@
 #include <linux/blkdev.h>
 #include <linux/module.h>
 #include <linux/blkpg.h>
+#include <linux/magic.h>
 #include <linux/buffer_head.h>
 #include <linux/swap.h>
 #include <linux/pagevec.h>
@@ -506,7 +507,7 @@
 static struct dentry *bd_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
-	return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, 0x62646576);
+	return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
 }
 
 static struct file_system_type bd_type = {