Commit 907ea17e authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

shmem: convert shmem_replace_page() to use folios throughout 

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.

Link: https://lkml.kernel.org/r/20220902194653.1739778-9-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 4cd400fd

include/linux/swap.h

+5 −0
Original line number Diff line number Diff line
@@ -355,6 +355,11 @@ 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);

mm/shmem.c

+32 −35
Original line number Diff line number Diff line
@@ -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,