btrfs: use pagevec_lookup_range_tag()

We want only pages from given range in btree_write_cache_pages() and
extent_write_cache_pages().  Use pagevec_lookup_range_tag() instead of
pagevec_lookup_tag() and remove unnecessary code.

Link: http://lkml.kernel.org/r/20171009151359.31984-3-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: David Sterba <dsterba@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/btrfs/extent_io.c

@@ -3814,8 +3814,8 @@ retry:
 	if (wbc->sync_mode == WB_SYNC_ALL)
 		tag_pages_for_writeback(mapping, index, end);
 	while (!done && !nr_to_write_done && (index <= end) &&
-	       (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
-			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
+	       (nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
+			tag, PAGEVEC_SIZE))) {
 		unsigned i;
 
 		scanned = 1;
@@ -3825,11 +3825,6 @@ retry:
 			if (!PagePrivate(page))
 				continue;
 
-			if (!wbc->range_cyclic && page->index > end) {
-				done = 1;
-				break;
-			}
-
 			spin_lock(&mapping->private_lock);
 			if (!PagePrivate(page)) {
 				spin_unlock(&mapping->private_lock);
@@ -3961,8 +3956,8 @@ retry:
 		tag_pages_for_writeback(mapping, index, end);
 	done_index = index;
 	while (!done && !nr_to_write_done && (index <= end) &&
-	       (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
-			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
+	       (nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
+			tag, PAGEVEC_SIZE))) {
 		unsigned i;
 
 		scanned = 1;
@@ -3987,12 +3982,6 @@ retry:
 				continue;
 			}
 
-			if (!wbc->range_cyclic && page->index > end) {
-				done = 1;
-				unlock_page(page);
-				continue;
-			}
-
 			if (wbc->sync_mode != WB_SYNC_NONE) {
 				if (PageWriteback(page))
 					flush_fn(data);