Commit 03104c2c authored by David Hildenbrand's avatar David Hildenbrand Committed by Linus Torvalds
Browse files

mm/swapfile: remove stale reuse_swap_page() 

All users are gone, let's remove it.  We'll let SWP_STABLE_WRITES stick
around for now, as it might come in handy in the near future.

Link: https://lkml.kernel.org/r/20220131162940.210846-8-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Liang Zhang <zhangliang5@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 363106c4

include/linux/swap.h

+0 −4
Original line number Diff line number Diff line
@@ -515,7 +515,6 @@ extern int __swp_swapcount(swp_entry_t entry); 
extern int swp_swapcount(swp_entry_t entry);

extern struct swap_info_struct *page_swap_info(struct page *);

extern struct swap_info_struct *swp_swap_info(swp_entry_t entry);

extern bool reuse_swap_page(struct page *);

extern int try_to_free_swap(struct page *);

struct backing_dev_info;

extern int init_swap_address_space(unsigned int type, unsigned long nr_pages);
@@ -681,9 +680,6 @@ static inline int swp_swapcount(swp_entry_t entry) 
	return 0;

}



#define reuse_swap_page(page) \

	(page_trans_huge_mapcount(page) == 1)



static inline int try_to_free_swap(struct page *page)

{

	return 0;

mm/swapfile.c

+0 −104
Original line number Diff line number Diff line
@@ -1167,16 +1167,6 @@ static struct swap_info_struct *_swap_info_get(swp_entry_t entry) 
	return NULL;

}



static struct swap_info_struct *swap_info_get(swp_entry_t entry)

{

	struct swap_info_struct *p;



	p = _swap_info_get(entry);

	if (p)

		spin_lock(&p->lock);

	return p;

}



static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry,

					struct swap_info_struct *q)

{
@@ -1601,100 +1591,6 @@ static bool page_swapped(struct page *page) 
	return false;

}



static int page_trans_huge_map_swapcount(struct page *page,

					 int *total_swapcount)

{

	int i, map_swapcount, _total_swapcount;

	unsigned long offset = 0;

	struct swap_info_struct *si;

	struct swap_cluster_info *ci = NULL;

	unsigned char *map = NULL;

	int swapcount = 0;



	/* hugetlbfs shouldn't call it */

	VM_BUG_ON_PAGE(PageHuge(page), page);



	if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) {

		if (PageSwapCache(page))

			swapcount = page_swapcount(page);

		if (total_swapcount)

			*total_swapcount = swapcount;

		return swapcount + page_trans_huge_mapcount(page);

	}



	page = compound_head(page);



	_total_swapcount = map_swapcount = 0;

	if (PageSwapCache(page)) {

		swp_entry_t entry;



		entry.val = page_private(page);

		si = _swap_info_get(entry);

		if (si) {

			map = si->swap_map;

			offset = swp_offset(entry);

		}

	}

	if (map)

		ci = lock_cluster(si, offset);

	for (i = 0; i < HPAGE_PMD_NR; i++) {

		int mapcount = atomic_read(&page[i]._mapcount) + 1;

		if (map) {

			swapcount = swap_count(map[offset + i]);

			_total_swapcount += swapcount;

		}

		map_swapcount = max(map_swapcount, mapcount + swapcount);

	}

	unlock_cluster(ci);



	if (PageDoubleMap(page))

		map_swapcount -= 1;



	if (total_swapcount)

		*total_swapcount = _total_swapcount;



	return map_swapcount + compound_mapcount(page);

}



/*

 * We can write to an anon page without COW if there are no other references

 * to it.  And as a side-effect, free up its swap: because the old content

 * on disk will never be read, and seeking back there to write new content

 * later would only waste time away from clustering.

 */

bool reuse_swap_page(struct page *page)

{

	int count, total_swapcount;



	VM_BUG_ON_PAGE(!PageLocked(page), page);

	if (unlikely(PageKsm(page)))

		return false;

	count = page_trans_huge_map_swapcount(page, &total_swapcount);

	if (count == 1 && PageSwapCache(page) &&

	    (likely(!PageTransCompound(page)) ||

	     /* The remaining swap count will be freed soon */

	     total_swapcount == page_swapcount(page))) {

		if (!PageWriteback(page)) {

			page = compound_head(page);

			delete_from_swap_cache(page);

			SetPageDirty(page);

		} else {

			swp_entry_t entry;

			struct swap_info_struct *p;



			entry.val = page_private(page);

			p = swap_info_get(entry);

			if (p->flags & SWP_STABLE_WRITES) {

				spin_unlock(&p->lock);

				return false;

			}

			spin_unlock(&p->lock);

		}

	}



	return count <= 1;

}



/*

 * 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.