This function can also be used elsewhere. I've left it in mincore.c for
now because I can't find a better place to put it.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
include/linux/pagemap.h | 1 +
mm/mincore.c | 59 +++++++++++++++++++++++------------------
2 files changed, 34 insertions(+), 26 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index cf2468da68e9..b921581a7dcf 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -386,6 +386,7 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index)
struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
+struct page *find_get_swap_page(struct address_space *mapping, pgoff_t index);
unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
unsigned int nr_entries, struct page **entries,
pgoff_t *indices);
diff --git a/mm/mincore.c b/mm/mincore.c
index 453ff112470f..abc24ca6f0f7 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -42,13 +42,44 @@ static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
return 0;
}
+/**
+ * find_get_swap_page - Find and get a page from the page or swap caches.
+ * @mapping: The address_space to search.
+ * @index: The page cache index.
+ *
+ * This is like find_get_page(), but if we find a swap entry for
+ * shmem/tmpfs, we also look in the swap cache for the page.
+ *
+ * Return: The found page or %NULL.
+ */
+struct page *find_get_swap_page(struct address_space *mapping, pgoff_t index)
+{
+ swp_entry_t swp;
+ struct swap_info_struct *si;
+ struct page *page = find_get_entry(mapping, index);
+
+ if (!xa_is_value(page))
+ return page;
+ if (!IS_ENABLED(CONFIG_SWAP) || !shmem_mapping(mapping))
+ return NULL;
+
+ swp = radix_to_swp_entry(page);
+ /* Prevent swapoff from happening to us */
+ si = get_swap_device(swp);
+ if (!si)
+ return NULL;
+ page = find_get_page(swap_address_space(swp), swp_offset(swp));
+ put_swap_device(si);
+ return page;
+}
+
/*
* Later we can get more picky about what "in core" means precisely.
* For now, simply check to see if the page is in the page cache,
* and is up to date; i.e. that no page-in operation would be required
* at this time if an application were to map and access this page.
*/
-static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
+static unsigned char mincore_page(struct address_space *mapping, pgoff_t index)
{
unsigned char present = 0;
struct page *page;
@@ -59,31 +90,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
* any other file mapping (ie. marked !present and faulted in with
* tmpfs's .fault). So swapped out tmpfs mappings are tested here.
*/
-#ifdef CONFIG_SWAP
- if (shmem_mapping(mapping)) {
- page = find_get_entry(mapping, pgoff);
- /*
- * shmem/tmpfs may return swap: account for swapcache
- * page too.
- */
- if (xa_is_value(page)) {
- swp_entry_t swp = radix_to_swp_entry(page);
- struct swap_info_struct *si;
-
- /* Prevent swap device to being swapoff under us */
- si = get_swap_device(swp);
- if (si) {
- page = find_get_page(swap_address_space(swp),
- swp_offset(swp));
- put_swap_device(si);
- } else
- page = NULL;
- }
- } else
- page = find_get_page(mapping, pgoff);
-#else
- page = find_get_page(mapping, pgoff);
-#endif
+ page = find_get_swap_page(mapping, index);
if (page) {
present = PageUptodate(page);
put_page(page);
--
2.27.0
