direct_IO: use iov_iter_rw() instead of rw everywhere

The rw parameter to direct_IO is redundant with iov_iter->type, and
treated slightly differently just about everywhere it's used: some users
do rw & WRITE, and others do rw == WRITE where they should be doing a
bitwise check. Simplify this with the new iov_iter_rw() helper, which
always returns either READ or WRITE.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/f2fs/data.c

@@ -1118,12 +1118,12 @@ static int f2fs_write_end(struct file *file,
 	return copied;
 }
 
-static int check_direct_IO(struct inode *inode, int rw,
-		struct iov_iter *iter, loff_t offset)
+static int check_direct_IO(struct inode *inode, struct iov_iter *iter,
+			   loff_t offset)
 {
 	unsigned blocksize_mask = inode->i_sb->s_blocksize - 1;
 
-	if (rw == READ)
+	if (iov_iter_rw(iter) == READ)
 		return 0;
 
 	if (offset & blocksize_mask)
@@ -1151,19 +1151,19 @@ static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
 			return err;
 	}
 
-	if (check_direct_IO(inode, rw, iter, offset))
+	if (check_direct_IO(inode, iter, offset))
 		return 0;
 
-	trace_f2fs_direct_IO_enter(inode, offset, count, rw);
+	trace_f2fs_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
 
-	if (rw & WRITE)
+	if (iov_iter_rw(iter) == WRITE)
 		__allocate_data_blocks(inode, offset, count);
 
 	err = blockdev_direct_IO(iocb, inode, iter, offset, get_data_block);
-	if (err < 0 && (rw & WRITE))
+	if (err < 0 && iov_iter_rw(iter) == WRITE)
 		f2fs_write_failed(mapping, offset + count);
 
-	trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);
+	trace_f2fs_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), err);
 
 	return err;
 }