[PATCH 34/35] mm: Make find_get_entries_tag() update index

[Jan Kara <jack@xxxxxxx>]

Make find_get_entries_tag() update 'start' to index the next page for
iteration.

Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 fs/dax.c                | 3 +--
 include/linux/pagemap.h | 2 +-
 mm/filemap.c            | 8 ++++++--
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index c204445a69b0..4b295c544fd4 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -841,7 +841,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 
 	pagevec_init(&pvec, 0);
 	while (!done) {
-		pvec.nr = find_get_entries_tag(mapping, start_index,
+		pvec.nr = find_get_entries_tag(mapping, &start_index,
 				PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
 				pvec.pages, indices);
 
@@ -859,7 +859,6 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 			if (ret < 0)
 				goto out;
 		}
-		start_index = indices[pvec.nr - 1] + 1;
 	}
 out:
 	put_dax(dax_dev);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index df128a56f44b..1dc7e54ec32a 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -365,7 +365,7 @@ static inline unsigned find_get_pages_tag(struct address_space *mapping,
 	return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
 					nr_pages, pages);
 }
-unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
+unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t *start,
 			int tag, unsigned int nr_entries,
 			struct page **entries, pgoff_t *indices);
 
diff --git a/mm/filemap.c b/mm/filemap.c
index e55100459710..3eb05c91c07a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1731,7 +1731,7 @@ EXPORT_SYMBOL(find_get_pages_range_tag);
  * Like find_get_entries, except we only return entries which are tagged with
  * @tag.
  */
-unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
+unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t *start,
 			int tag, unsigned int nr_entries,
 			struct page **entries, pgoff_t *indices)
 {
@@ -1744,7 +1744,7 @@ unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
 
 	rcu_read_lock();
 	radix_tree_for_each_tagged(slot, &mapping->page_tree,
-				   &iter, start, tag) {
+				   &iter, *start, tag) {
 		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
@@ -1786,6 +1786,10 @@ unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
 			break;
 	}
 	rcu_read_unlock();
+
+	if (ret)
+		*start = indices[ret - 1] + 1;
+
 	return ret;
 }
 EXPORT_SYMBOL(find_get_entries_tag);
-- 
2.12.3