mm/page-writeback.c: write_cache_pages(): deduplicate identical checks

There used to be a 'retry' label in between the two (identical) checks when first introduced in commit f446daaea9d4 ("mm: implement writeback livelock avoidance using page tagging"), and later modified/updated in commit 6e6938b6d313 ("writeback: introduce .tagged_writepages for the WB_SYNC_NONE sync stage").

The label has been removed in commit 64081362e8ff ("mm/page-writeback.c:
fix range_cyclic writeback vs writepages deadlock"), and the (identical) checks are now present / performed immediately one after another.

So, remove/deduplicate the latter check, moving tag_pages_for_writeback() into the former check before the 'tag' variable assignment, so it's clear that it's not used in this (similarly-named) function call but only later in pagevec_lookup_range_tag().

---
 mm/page-writeback.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index 2caf780a42e7..86c18112b89b 100644
@@ -2183,11 +2183,10 @@ int write_cache_pages(struct address_space *mapping,
 			range_whole = 1;
 	}
 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		tag_pages_for_writeback(mapping, index, end);
 		tag = PAGECACHE_TAG_TOWRITE;
 	else
 		tag = PAGECACHE_TAG_DIRTY;
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-		tag_pages_for_writeback(mapping, index, end);
 	done_index = index;
 	while (!done && (index <= end)) {
 		int i;

2.20.1