Introduce folio_set_swap_entry() to abstract how both folio->private
and swp_entry_t work. Use swap_address_space() directly instead of
indirecting through folio_mapping(). Include an assertion that the old
folio is not large as we only allocate a single-page folio to replace it.
Use folio_put_refs() instead of calling folio_put() twice.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
include/linux/swap.h | 5 ++++
mm/shmem.c | 67 +++++++++++++++++++++-----------------------
2 files changed, 37 insertions(+), 35 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 333d5588dc2d..afcb76bbd141 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -351,6 +351,11 @@ static inline swp_entry_t folio_swap_entry(struct folio *folio)
return entry;
}
+static inline void folio_set_swap_entry(struct folio *folio, swp_entry_t entry)
+{
+ folio->private = (void *)entry.val;
+}
+
/* linux/mm/workingset.c */
void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg);
diff --git a/mm/shmem.c b/mm/shmem.c
index 9e851fc87601..4113f1b9d4a8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1560,12 +1560,6 @@ static struct folio *shmem_alloc_folio(gfp_t gfp,
return folio;
}
-static struct page *shmem_alloc_page(gfp_t gfp,
- struct shmem_inode_info *info, pgoff_t index)
-{
- return &shmem_alloc_folio(gfp, info, index)->page;
-}
-
static struct folio *shmem_alloc_and_acct_folio(gfp_t gfp, struct inode *inode,
pgoff_t index, bool huge)
{
@@ -1617,51 +1611,49 @@ static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp)
static int shmem_replace_page(struct page **pagep, gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
- struct page *oldpage, *newpage;
struct folio *old, *new;
struct address_space *swap_mapping;
swp_entry_t entry;
pgoff_t swap_index;
int error;
- oldpage = *pagep;
- entry.val = page_private(oldpage);
+ old = page_folio(*pagep);
+ entry = folio_swap_entry(old);
swap_index = swp_offset(entry);
- swap_mapping = page_mapping(oldpage);
+ swap_mapping = swap_address_space(entry);
/*
* We have arrived here because our zones are constrained, so don't
* limit chance of success by further cpuset and node constraints.
*/
gfp &= ~GFP_CONSTRAINT_MASK;
- newpage = shmem_alloc_page(gfp, info, index);
- if (!newpage)
+ VM_BUG_ON_FOLIO(folio_test_large(old), old);
+ new = shmem_alloc_folio(gfp, info, index);
+ if (!new)
return -ENOMEM;
- get_page(newpage);
- copy_highpage(newpage, oldpage);
- flush_dcache_page(newpage);
+ folio_get(new);
+ folio_copy(new, old);
+ flush_dcache_folio(new);
- __SetPageLocked(newpage);
- __SetPageSwapBacked(newpage);
- SetPageUptodate(newpage);
- set_page_private(newpage, entry.val);
- SetPageSwapCache(newpage);
+ __folio_set_locked(new);
+ __folio_set_swapbacked(new);
+ folio_mark_uptodate(new);
+ folio_set_swap_entry(new, entry);
+ folio_set_swapcache(new);
/*
* Our caller will very soon move newpage out of swapcache, but it's
* a nice clean interface for us to replace oldpage by newpage there.
*/
xa_lock_irq(&swap_mapping->i_pages);
- error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
+ error = shmem_replace_entry(swap_mapping, swap_index, old, new);
if (!error) {
- old = page_folio(oldpage);
- new = page_folio(newpage);
mem_cgroup_migrate(old, new);
- __inc_lruvec_page_state(newpage, NR_FILE_PAGES);
- __inc_lruvec_page_state(newpage, NR_SHMEM);
- __dec_lruvec_page_state(oldpage, NR_FILE_PAGES);
- __dec_lruvec_page_state(oldpage, NR_SHMEM);
+ __lruvec_stat_mod_folio(new, NR_FILE_PAGES, 1);
+ __lruvec_stat_mod_folio(new, NR_SHMEM, 1);
+ __lruvec_stat_mod_folio(old, NR_FILE_PAGES, -1);
+ __lruvec_stat_mod_folio(old, NR_SHMEM, -1);
}
xa_unlock_irq(&swap_mapping->i_pages);
@@ -1671,18 +1663,17 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
* both PageSwapCache and page_private after getting page lock;
* but be defensive. Reverse old to newpage for clear and free.
*/
- oldpage = newpage;
+ old = new;
} else {
- lru_cache_add(newpage);
- *pagep = newpage;
+ folio_add_lru(new);
+ *pagep = &new->page;
}
- ClearPageSwapCache(oldpage);
- set_page_private(oldpage, 0);
+ folio_clear_swapcache(old);
+ old->private = NULL;
- unlock_page(oldpage);
- put_page(oldpage);
- put_page(oldpage);
+ folio_unlock(old);
+ folio_put_refs(old, 2);
return error;
}
@@ -2383,6 +2374,12 @@ static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir,
}
#ifdef CONFIG_USERFAULTFD
+static struct page *shmem_alloc_page(gfp_t gfp,
+ struct shmem_inode_info *info, pgoff_t index)
+{
+ return &shmem_alloc_folio(gfp, info, index)->page;
+}
+
int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
pmd_t *dst_pmd,
struct vm_area_struct *dst_vma,
--
2.35.1
