[PATCH v14 081/138] mm: Add folio_evictable()

Matthew Wilcox (Oracle)
2021-07-15T04:43:49Z

This is the folio equivalent of page_evictable(). Unfortunately, it's
different from !folio_test_unevictable(), but I think it's used in places
where you have to be a VM expert and can reasonably be expected to know
the difference.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
mm/internal.h | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 08e8a28994d1..0910efec5821 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -72,17 +72,28 @@ unsigned find_lock_entries(struct address_space *mapping, pgoff_t start,
pgoff_t end, struct pagevec *pvec, pgoff_t *indices);

/**
- * page_evictable - test whether a page is evictable
- * @page: the page to test
+ * folio_evictable - Test whether a folio is evictable.
+ * @folio: The folio to test.
*
- * Test whether page is evictable--i.e., should be placed on active/inactive
- * lists vs unevictable list.
- *
- * Reasons page might not be evictable:
- * (1) page's mapping marked unevictable
- * (2) page is part of an mlocked VMA
+ * Test whether @folio is evictable -- i.e., should be placed on
+ * active/inactive lists vs unevictable list.
*
+ * Reasons folio might not be evictable:
+ * 1. folio's mapping marked unevictable
+ * 2. One of the pages in the folio is part of an mlocked VMA
*/
+static inline bool folio_evictable(struct folio *folio)
+{
+ bool ret;
+
+ /* Prevent address_space of inode and swap cache from being freed */
+ rcu_read_lock();
+ ret = !mapping_unevictable(folio_mapping(folio)) &&
+ !folio_test_mlocked(folio);
+ rcu_read_unlock();
+ return ret;
+}
+
static inline bool page_evictable(struct page *page)
{
bool ret;
--
2.30.2