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-rw-r--r--mm/filemap.c42
1 files changed, 30 insertions, 12 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index ab9011408d81..129883f160a7 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1557,24 +1557,29 @@ export:
}
/**
- * find_get_pages - gang pagecache lookup
+ * find_get_pages_range - gang pagecache lookup
* @mapping: The address_space to search
* @start: The starting page index
+ * @end: The final page index (inclusive)
* @nr_pages: The maximum number of pages
* @pages: Where the resulting pages are placed
*
- * find_get_pages() will search for and return a group of up to
- * @nr_pages pages in the mapping. The pages are placed at @pages.
- * find_get_pages() takes a reference against the returned pages.
+ * find_get_pages_range() will search for and return a group of up to @nr_pages
+ * pages in the mapping starting at index @start and up to index @end
+ * (inclusive). The pages are placed at @pages. find_get_pages_range() takes
+ * a reference against the returned pages.
*
* 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.
+ * find_get_pages_range() returns the number of pages which were found. If this
+ * number is smaller than @nr_pages, the end of specified range has been
+ * reached.
*/
-unsigned find_get_pages(struct address_space *mapping, pgoff_t *start,
- unsigned int nr_pages, struct page **pages)
+unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
+ pgoff_t end, unsigned int nr_pages,
+ struct page **pages)
{
struct radix_tree_iter iter;
void **slot;
@@ -1586,6 +1591,9 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t *start,
rcu_read_lock();
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, *start) {
struct page *head, *page;
+
+ if (iter.index > end)
+ break;
repeat:
page = radix_tree_deref_slot(slot);
if (unlikely(!page))
@@ -1621,15 +1629,25 @@ repeat:
}
pages[ret] = page;
- if (++ret == nr_pages)
- break;
+ if (++ret == nr_pages) {
+ *start = pages[ret - 1]->index + 1;
+ goto out;
+ }
}
+ /*
+ * We come here when there is no page beyond @end. We take care to not
+ * overflow the index @start as it confuses some of the callers. This
+ * breaks the iteration when there is page at index -1 but that is
+ * already broken anyway.
+ */
+ if (end == (pgoff_t)-1)
+ *start = (pgoff_t)-1;
+ else
+ *start = end + 1;
+out:
rcu_read_unlock();
- if (ret)
- *start = pages[ret - 1]->index + 1;
-
return ret;
}