Add kernel-doc for folio_free_swap() and make it return bool.
Add a try_to_free_swap() compatibility wrapper.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
include/linux/swap.h | 6 ++++++
mm/folio-compat.c | 7 +++++++
mm/swapfile.c | 32 ++++++++++++++++++--------------
mm/vmscan.c | 2 +-
4 files changed, 32 insertions(+), 15 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index afcb76bbd141..4595cbc1cb02 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -486,6 +486,7 @@ static inline long get_nr_swap_pages(void)
extern void si_swapinfo(struct sysinfo *);
swp_entry_t folio_alloc_swap(struct folio *folio);
+bool folio_free_swap(struct folio *folio);
extern void put_swap_page(struct page *page, swp_entry_t entry);
extern swp_entry_t get_swap_page_of_type(int);
extern int get_swap_pages(int n, swp_entry_t swp_entries[], int entry_size);
@@ -602,6 +603,11 @@ static inline swp_entry_t folio_alloc_swap(struct folio *folio)
return entry;
}
+static inline bool folio_free_swap(struct folio *folio)
+{
+ return false;
+}
+
static inline int add_swap_extent(struct swap_info_struct *sis,
unsigned long start_page,
unsigned long nr_pages, sector_t start_block)
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index e1e23b4947d7..06d47f00609b 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -146,3 +146,10 @@ void putback_lru_page(struct page *page)
{
folio_putback_lru(page_folio(page));
}
+
+#ifdef CONFIG_SWAP
+int try_to_free_swap(struct page *page)
+{
+ return folio_free_swap(page_folio(page));
+}
+#endif
diff --git a/mm/swapfile.c b/mm/swapfile.c
index c042fd71de02..880871f4c6d4 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1563,43 +1563,47 @@ static bool folio_swapped(struct folio *folio)
return swap_page_trans_huge_swapped(si, entry);
}
-/*
- * If swap is getting full, or if there are no more mappings of this page,
- * then try_to_free_swap is called to free its swap space.
+/**
+ * folio_free_swap() - Free the swap space used for this folio.
+ * @folio: The folio to remove.
+ *
+ * If swap is getting full, or if there are no more mappings of this folio,
+ * then call folio_free_swap to free its swap space.
+ *
+ * Return: true if we were able to release the swap space.
*/
-int try_to_free_swap(struct page *page)
+bool folio_free_swap(struct folio *folio)
{
- struct folio *folio = page_folio(page);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
if (!folio_test_swapcache(folio))
- return 0;
+ return false;
if (folio_test_writeback(folio))
- return 0;
+ return false;
if (folio_swapped(folio))
- return 0;
+ return false;
/*
* Once hibernation has begun to create its image of memory,
- * there's a danger that one of the calls to try_to_free_swap()
+ * there's a danger that one of the calls to folio_free_swap()
* - most probably a call from __try_to_reclaim_swap() while
* hibernation is allocating its own swap pages for the image,
* but conceivably even a call from memory reclaim - will free
- * the swap from a page which has already been recorded in the
- * image as a clean swapcache page, and then reuse its swap for
+ * the swap from a folio which has already been recorded in the
+ * image as a clean swapcache folio, and then reuse its swap for
* another page of the image. On waking from hibernation, the
- * original page might be freed under memory pressure, then
+ * original folio might be freed under memory pressure, then
* later read back in from swap, now with the wrong data.
*
* Hibernation suspends storage while it is writing the image
* to disk so check that here.
*/
if (pm_suspended_storage())
- return 0;
+ return false;
delete_from_swap_cache(folio);
folio_set_dirty(folio);
- return 1;
+ return true;
}
/*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 93b1087fc969..d3e26712dbc1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2004,7 +2004,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
if (folio_test_swapcache(folio) &&
(mem_cgroup_swap_full(&folio->page) ||
folio_test_mlocked(folio)))
- try_to_free_swap(&folio->page);
+ folio_free_swap(folio);
VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
if (!folio_test_mlocked(folio)) {
int type = folio_is_file_lru(folio);
--
2.35.1
