direct-io: eliminate the offset argument to ->direct_IO

Including blkdev_direct_IO and dax_do_io.  It has to be ki_pos to actually
work, so eliminate the superflous argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/jfs/inode.c b/fs/jfs/inode.c
index 9d9bae6..f6a2a78 100644
--- a/fs/jfs/inode.c
+++ b/fs/jfs/inode.c
@@ -332,8 +332,7 @@
 	return generic_block_bmap(mapping, block, jfs_get_block);
 }
 
-static ssize_t jfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
-			     loff_t offset)
+static ssize_t jfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
@@ -341,7 +340,7 @@
 	size_t count = iov_iter_count(iter);
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(iocb, inode, iter, offset, jfs_get_block);
+	ret = blockdev_direct_IO(iocb, inode, iter, jfs_get_block);
 
 	/*
 	 * In case of error extending write may have instantiated a few
@@ -349,7 +348,7 @@
 	 */
 	if (unlikely(iov_iter_rw(iter) == WRITE && ret < 0)) {
 		loff_t isize = i_size_read(inode);
-		loff_t end = offset + count;
+		loff_t end = iocb->ki_pos + count;
 
 		if (end > isize)
 			jfs_write_failed(mapping, end);