commit d72dc8a25afc71ce90ee92bdd77550e9beb85d4d
author Jan Kara <jack@suse.cz> Wed Sep 06 16:21:18 2017 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> Wed Sep 06 17:27:26 2017 -0700
tree da47df20fe7bd2672f8368a2545f82e17703820b
parent 26b433d0da062d6e19d75350c0171d3cf8ff560d

mm: make pagevec_lookup() update index

Make pagevec_lookup() (and underlying find_get_pages()) update index to
the next page where iteration should continue.  Most callers want this
and also pagevec_lookup_tag() already does this.

Link: http://lkml.kernel.org/r/20170726114704.7626-3-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index dad9357..ab90114 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -403,7 +403,7 @@ bool filemap_range_has_page(struct address_space *mapping,
 		return false;
 
 	pagevec_init(&pvec, 0);
-	if (!pagevec_lookup(&pvec, mapping, index, 1))
+	if (!pagevec_lookup(&pvec, mapping, &index, 1))
 		return false;
 	ret = (pvec.pages[0]->index <= end);
 	pagevec_release(&pvec);
@@ -1569,10 +1569,11 @@ unsigned find_get_entries(struct address_space *mapping,
  *
  * The search returns a group of mapping-contiguous pages with ascending
  * indexes.  There may be holes in the indices due to not-present pages.
+ * We also update @start to index the next page for the traversal.
  *
  * find_get_pages() returns the number of pages which were found.
  */
-unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
+unsigned find_get_pages(struct address_space *mapping, pgoff_t *start,
 			    unsigned int nr_pages, struct page **pages)
 {
 	struct radix_tree_iter iter;
@@ -1583,7 +1584,7 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, *start) {
 		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
@@ -1625,6 +1626,10 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
 	}
 
 	rcu_read_unlock();
+
+	if (ret)
+		*start = pages[ret - 1]->index + 1;
+
 	return ret;
 }
 

mm/swap.c

diff --git a/mm/swap.c b/mm/swap.c
index 60b1d2a..4bffd11 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -957,12 +957,13 @@ void pagevec_remove_exceptionals(struct pagevec *pvec)
  * reference against the pages in @pvec.
  *
  * The search returns a group of mapping-contiguous pages with ascending
- * indexes.  There may be holes in the indices due to not-present pages.
+ * indexes.  There may be holes in the indices due to not-present pages. We
+ * also update @start to index the next page for the traversal.
  *
  * pagevec_lookup() returns the number of pages which were found.
  */
 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
-		pgoff_t start, unsigned nr_pages)
+		pgoff_t *start, unsigned nr_pages)
 {
 	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
 	return pagevec_count(pvec);