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>
diff --git a/fs/affs/file.c b/fs/affs/file.c
index 1edc0d4..7f05a46 100644
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -398,7 +398,7 @@
 	size_t count = iov_iter_count(iter);
 	ssize_t ret;
 
-	if (rw == WRITE) {
+	if (iov_iter_rw(iter) == WRITE) {
 		loff_t size = offset + count;
 
 		if (AFFS_I(inode)->mmu_private < size)
@@ -406,7 +406,7 @@
 	}
 
 	ret = blockdev_direct_IO(iocb, inode, iter, offset, affs_get_block);
-	if (ret < 0 && (rw & WRITE))
+	if (ret < 0 && iov_iter_rw(iter) == WRITE)
 		affs_write_failed(mapping, offset + count);
 	return ret;
 }