fs: simplify the blockdev_direct_IO prototype

Simple filesystems always pass inode->i_sb_bdev as the block device
argument, and never need a end_io handler.  Let's simply things for
them and for my grepping activity by dropping these arguments.  The
only thing not falling into that scheme is ext4, which passes and
end_io handler without needing special flags (yet), but given how
messy the direct I/O code there is use of __blockdev_direct_IO
in one instead of two out of three cases isn't going to make a large
difference anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2fe9207..824453b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2418,12 +2418,11 @@
 	dio_submit_t submit_io,	int flags);
 
 static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
-	struct inode *inode, struct block_device *bdev, const struct iovec *iov,
-	loff_t offset, unsigned long nr_segs, get_block_t get_block,
-	dio_iodone_t end_io)
+		struct inode *inode, const struct iovec *iov, loff_t offset,
+		unsigned long nr_segs, get_block_t get_block)
 {
-	return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
-				    nr_segs, get_block, end_io, NULL,
+	return __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
+				    offset, nr_segs, get_block, NULL, NULL,
 				    DIO_LOCKING | DIO_SKIP_HOLES);
 }
 #endif