[PATCH v6 34/99] mm: Convert delete_from_swap_cache to XArray

From: Matthew Wilcox
Date: Wed Jan 17 2018 - 16:01:59 EST


From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>

Both callers of __delete_from_swap_cache have the swp_entry_t already,
so pass that in to make constructing the XA_STATE easier.

Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
---
include/linux/swap.h | 5 +++--
mm/swap_state.c | 24 ++++++++++--------------
mm/vmscan.c | 2 +-
3 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index e519554730fa..8eb99229dbc0 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -408,7 +408,7 @@ extern void show_swap_cache_info(void);
extern int add_to_swap(struct page *page);
extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
-extern void __delete_from_swap_cache(struct page *);
+extern void __delete_from_swap_cache(struct page *, swp_entry_t entry);
extern void delete_from_swap_cache(struct page *);
extern void free_page_and_swap_cache(struct page *);
extern void free_pages_and_swap_cache(struct page **, int);
@@ -583,7 +583,8 @@ static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
return -1;
}

-static inline void __delete_from_swap_cache(struct page *page)
+static inline void __delete_from_swap_cache(struct page *page,
+ swp_entry_t entry)
{
}

diff --git a/mm/swap_state.c b/mm/swap_state.c
index a57b5ad4c503..219e3b4f09e6 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -154,23 +154,22 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
* This must be called only on pages that have
* been verified to be in the swap cache.
*/
-void __delete_from_swap_cache(struct page *page)
+void __delete_from_swap_cache(struct page *page, swp_entry_t entry)
{
- struct address_space *address_space;
+ struct address_space *address_space = swap_address_space(entry);
int i, nr = hpage_nr_pages(page);
- swp_entry_t entry;
- pgoff_t idx;
+ pgoff_t idx = swp_offset(entry);
+ XA_STATE(xas, &address_space->pages, idx);

VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(!PageSwapCache(page), page);
VM_BUG_ON_PAGE(PageWriteback(page), page);

- entry.val = page_private(page);
- address_space = swap_address_space(entry);
- idx = swp_offset(entry);
for (i = 0; i < nr; i++) {
- radix_tree_delete(&address_space->pages, idx + i);
+ void *entry = xas_store(&xas, NULL);
+ VM_BUG_ON_PAGE(entry != page + i, entry);
set_page_private(page + i, 0);
+ xas_next(&xas);
}
ClearPageSwapCache(page);
address_space->nrpages -= nr;
@@ -246,14 +245,11 @@ int add_to_swap(struct page *page)
*/
void delete_from_swap_cache(struct page *page)
{
- swp_entry_t entry;
- struct address_space *address_space;
-
- entry.val = page_private(page);
+ swp_entry_t entry = { .val = page_private(page) };
+ struct address_space *address_space = swap_address_space(entry);

- address_space = swap_address_space(entry);
xa_lock_irq(&address_space->pages);
- __delete_from_swap_cache(page);
+ __delete_from_swap_cache(page, entry);
xa_unlock_irq(&address_space->pages);

put_swap_page(page, entry);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2fa675a2db31..51d437a18db8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -718,7 +718,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
if (PageSwapCache(page)) {
swp_entry_t swap = { .val = page_private(page) };
mem_cgroup_swapout(page, swap);
- __delete_from_swap_cache(page);
+ __delete_from_swap_cache(page, swap);
xa_unlock_irqrestore(&mapping->pages, flags);
put_swap_page(page, swap);
} else {
--
2.15.1