mm/page-writeback.c: remove unused variable

Commit 64081362 ("mm/page-writeback.c: fix range_cyclic writeback
vs writepages deadlock") left unused variable, remove it.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/20200528033740.17269-1-yuchao0@huawei.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/page-writeback.c

@@ -2164,7 +2164,6 @@ int write_cache_pages(struct address_space *mapping,
 	int error;
 	struct pagevec pvec;
 	int nr_pages;
-	pgoff_t uninitialized_var(writeback_index);
 	pgoff_t index;
 	pgoff_t end;		/* Inclusive */
 	pgoff_t done_index;
@@ -2173,8 +2172,7 @@ int write_cache_pages(struct address_space *mapping,
 
 	pagevec_init(&pvec);
 	if (wbc->range_cyclic) {
-		writeback_index = mapping->writeback_index; /* prev offset */
-		index = writeback_index;
+		index = mapping->writeback_index; /* prev offset */
 		end = -1;
 	} else {
 		index = wbc->range_start >> PAGE_SHIFT;