[PATCH 33/62] page cache: Convert page_cache_next_hole to XArray

Matthew Wilcox
2017-11-22T21:18:18Z

Use xas_find_any() to scan the entries instead of doing a lookup from
the top of the tree each time.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
mm/filemap.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 1c03b0ea105e..accc350f9544 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1349,20 +1349,15 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
pgoff_t page_cache_next_hole(struct address_space *mapping,
pgoff_t index, unsigned long max_scan)
{
- unsigned long i;
-
- for (i = 0; i < max_scan; i++) {
- struct page *page;
+ XA_STATE(xas, index);

- page = radix_tree_lookup(&mapping->pages, index);
- if (!page || xa_is_value(page))
- break;
- index++;
- if (index == 0)
+ while (max_scan--) {
+ void *entry = xas_find_any(&mapping->pages, &xas);
+ if (!entry || xa_is_value(entry))
break;
}

- return index;
+ return xas.xa_index;
}
EXPORT_SYMBOL(page_cache_next_hole);

--
2.15.0