ext4: clean up some wait_on_page_writeback calls

wait_on_page_writeback already checks the writeback bit, so callers of it
needn't do that test.
Signed-off-by: NDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -2796,9 +2796,7 @@ static int write_cache_pages_da(struct address_space *mapping,
 				continue;
 			}
 
-			if (PageWriteback(page))
 			wait_on_page_writeback(page);
-
 			BUG_ON(PageWriteback(page));
 
 			if (mpd->next_page != page->index)

fs/ext4/move_extent.c

@@ -876,7 +876,6 @@ move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
 	 * It needs to call wait_on_page_writeback() to wait for the
 	 * writeback of the page.
 	 */
-	if (PageWriteback(page))
 	wait_on_page_writeback(page);
 
 	/* Release old bh and drop refs */