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/ext3/inode.c b/fs/ext3/inode.c
index 6fb376c..c70839d 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -1832,9 +1832,9 @@
 	size_t count = iov_iter_count(iter);
 	int retries = 0;
 
-	trace_ext3_direct_IO_enter(inode, offset, count, rw);
+	trace_ext3_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
 
-	if (rw == WRITE) {
+	if (iov_iter_rw(iter) == WRITE) {
 		loff_t final_size = offset + count;
 
 		if (final_size > inode->i_size) {
@@ -1861,7 +1861,7 @@
 	 * In case of error extending write may have instantiated a few
 	 * blocks outside i_size. Trim these off again.
 	 */
-	if (unlikely((rw & WRITE) && ret < 0)) {
+	if (unlikely(iov_iter_rw(iter) == WRITE && ret < 0)) {
 		loff_t isize = i_size_read(inode);
 		loff_t end = offset + count;
 
@@ -1908,7 +1908,7 @@
 			ret = err;
 	}
 out:
-	trace_ext3_direct_IO_exit(inode, offset, count, rw, ret);
+	trace_ext3_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), ret);
 	return ret;
 }