[PATCH 35/62] page cache: Convert page_cache_tree_delete to xarray

Matthew Wilcox
2017-11-22T21:14:35Z

The code is slightly shorter and simpler.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
mm/filemap.c | 26 ++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 1d520748789b..f60f22867a1a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -115,27 +115,25 @@
static void page_cache_tree_delete(struct address_space *mapping,
struct page *page, void *shadow)
{
- int i, nr;
+ XA_STATE(xas, page->index);
+ unsigned int i, nr;

- /* hugetlb pages are represented by one entry in the radix tree */
+ xas_set_update(&xas, workingset_lookup_update(mapping));
+
+ /* hugetlb pages are represented by a single entry in the xarray */
nr = PageHuge(page) ? 1 : hpage_nr_pages(page);

VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(PageTail(page), page);
VM_BUG_ON_PAGE(nr != 1 && shadow, page);

- for (i = 0; i < nr; i++) {
- struct radix_tree_node *node;
- void **slot;
-
- __radix_tree_lookup(&mapping->pages, page->index + i,
- &node, &slot);
-
- VM_BUG_ON_PAGE(!node && nr != 1, page);
-
- radix_tree_clear_tags(&mapping->pages, node, slot);
- __radix_tree_replace(&mapping->pages, node, slot, shadow,
- workingset_lookup_update(mapping));
+ i = nr;
+repeat:
+ xas_store(&mapping->pages, &xas, shadow);
+ xas_init_tags(&mapping->pages, &xas);
+ if (--i) {
+ xas_next_any(&mapping->pages, &xas);
+ goto repeat;
}

page->mapping = NULL;
--
2.15.0