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>

1 files changed, 8 insertions, 3 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index dad935769055..ab9011408d81 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 @@ export:
  *
  * 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 @@ repeat:
         }
 
         rcu_read_unlock();
+
+        if (ret)
+                *start = pages[ret - 1]->index + 1;
+
         return ret;
 }