block: move block-related definitions out of fs.h

Move most of the block related definition out of fs.h into more suitable
headers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index 2f224b9..f35a37c 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -17,6 +17,7 @@
 #include <linux/cred.h>
 #include <linux/uio.h>
 #include <linux/xattr.h>
+#include <linux/blkdev.h>
 
 #include "hfs_fs.h"
 #include "btree.h"