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/affs/file.c b/fs/affs/file.c
index a85817f..a26a0f9 100644
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -14,6 +14,7 @@
  */
 
 #include <linux/uio.h>
+#include <linux/blkdev.h>
 #include "affs.h"
 
 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);