LUR: Revert "BACKPORT: mm/swapcache: support to handle the shadow entries"

The LRU function is not compatible with GKI,
causing GKI to fail to start, so revert.

This reverts commit 1968691ba29356ec6e407f6691ccd3fc5b16f38b.

Change-Id: I410b200e5c30b6aa189c424ae9afd6c9288c3e40
Reviewed-on: https://gerrit.mot.com/2609775
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key

include/linux/swap.h

@@ -415,13 +415,10 @@ extern struct address_space *swapper_spaces[];
 extern unsigned long total_swapcache_pages(void);
 extern void show_swap_cache_info(void);
 extern int add_to_swap(struct page *page);
-extern int add_to_swap_cache(struct page *page, swp_entry_t entry,
-			gfp_t gfp, void **shadowp);
-extern void __delete_from_swap_cache(struct page *page,
-			swp_entry_t entry, void *shadow);
+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 *, swp_entry_t entry);
 extern void delete_from_swap_cache(struct page *);
-extern void clear_shadow_from_swap_cache(int type, unsigned long begin,
-				unsigned long end);
 extern void free_page_and_swap_cache(struct page *);
 extern void free_pages_and_swap_cache(struct page **, int);
 extern struct page *lookup_swap_cache(swp_entry_t entry,
@@ -576,13 +573,13 @@ static inline int add_to_swap(struct page *page)
 }
 
 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
-					gfp_t gfp_mask, void **shadowp)
+							gfp_t gfp_mask)
 {
 	return -1;
 }
 
 static inline void __delete_from_swap_cache(struct page *page,
-					swp_entry_t entry, void *shadow)
+							swp_entry_t entry)
 {
 }
 
@@ -590,11 +587,6 @@ static inline void delete_from_swap_cache(struct page *page)
 {
 }
 
-static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
-				unsigned long end)
-{
-}
-
 static inline int page_swapcount(struct page *page)
 {
 	return 0;

mm/shmem.c

@@ -1374,7 +1374,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 	if (list_empty(&info->swaplist))
 		list_add(&info->swaplist, &shmem_swaplist);
 
-	if (add_to_swap_cache(page, swap, GFP_ATOMIC, NULL) == 0) {
+	if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
 		spin_lock_irq(&info->lock);
 		shmem_recalc_inode(inode);
 		info->swapped++;

mm/swap_state.c

@@ -112,14 +112,12 @@ void show_swap_cache_info(void)
  * add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
  * but sets SwapCache flag and private instead of mapping and index.
  */
-int add_to_swap_cache(struct page *page, swp_entry_t entry,
-			gfp_t gfp, void **shadowp)
+int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
 {
 	struct address_space *address_space = swap_address_space(entry);
 	pgoff_t idx = swp_offset(entry);
 	XA_STATE_ORDER(xas, &address_space->i_pages, idx, compound_order(page));
-	unsigned long i, nr = hpage_nr_pages(page);
-	void *old;
+	unsigned long i, nr = compound_nr(page);
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageSwapCache(page), page);
@@ -129,25 +127,16 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry,
 	SetPageSwapCache(page);
 
 	do {
-		unsigned long nr_shadows = 0;
-
 		xas_lock_irq(&xas);
 		xas_create_range(&xas);
 		if (xas_error(&xas))
 			goto unlock;
 		for (i = 0; i < nr; i++) {
 			VM_BUG_ON_PAGE(xas.xa_index != idx + i, page);
-			old = xas_load(&xas);
-			if (xa_is_value(old)) {
-				nr_shadows++;
-				if (shadowp)
-					*shadowp = old;
-			}
 			set_page_private(page + i, entry.val + i);
 			xas_store(&xas, page);
 			xas_next(&xas);
 		}
-		address_space->nrexceptional -= nr_shadows;
 		address_space->nrpages += nr;
 		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
 		ADD_CACHE_INFO(add_total, nr);
@@ -167,8 +156,7 @@ unlock:
  * 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,
-			swp_entry_t entry, void *shadow)
+void __delete_from_swap_cache(struct page *page, swp_entry_t entry)
 {
 	struct address_space *address_space = swap_address_space(entry);
 	int i, nr = hpage_nr_pages(page);
@@ -180,14 +168,12 @@ void __delete_from_swap_cache(struct page *page,
 	VM_BUG_ON_PAGE(PageWriteback(page), page);
 
 	for (i = 0; i < nr; i++) {
-		void *entry = xas_store(&xas, shadow);
+		void *entry = xas_store(&xas, NULL);
 		VM_BUG_ON_PAGE(entry != page, entry);
 		set_page_private(page + i, 0);
 		xas_next(&xas);
 	}
 	ClearPageSwapCache(page);
-	if (shadow)
-		address_space->nrexceptional += nr;
 	address_space->nrpages -= nr;
 	__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
 	ADD_CACHE_INFO(del_total, nr);
@@ -224,7 +210,7 @@ int add_to_swap(struct page *page)
 	 * Add it to the swap cache.
 	 */
 	err = add_to_swap_cache(page, entry,
-			__GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN, NULL);
+			__GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
 	if (err)
 		/*
 		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
@@ -262,44 +248,13 @@ void delete_from_swap_cache(struct page *page)
 	struct address_space *address_space = swap_address_space(entry);
 
 	xa_lock_irq(&address_space->i_pages);
-	__delete_from_swap_cache(page, entry, NULL);
+	__delete_from_swap_cache(page, entry);
 	xa_unlock_irq(&address_space->i_pages);
 
 	put_swap_page(page, entry);
 	page_ref_sub(page, hpage_nr_pages(page));
 }
 
-void clear_shadow_from_swap_cache(int type, unsigned long begin,
-				unsigned long end)
-{
-	unsigned long curr = begin;
-	void *old;
-
-	for (;;) {
-		unsigned long nr_shadows = 0;
-		swp_entry_t entry = swp_entry(type, curr);
-		struct address_space *address_space = swap_address_space(entry);
-		XA_STATE(xas, &address_space->i_pages, curr);
-
-		xa_lock_irq(&address_space->i_pages);
-		xas_for_each(&xas, old, end) {
-			if (!xa_is_value(old))
-				continue;
-			xas_store(&xas, NULL);
-			nr_shadows++;
-		}
-		address_space->nrexceptional -= nr_shadows;
-		xa_unlock_irq(&address_space->i_pages);
-
-		/* search the next swapcache until we meet end */
-		curr >>= SWAP_ADDRESS_SPACE_SHIFT;
-		curr++;
-		curr <<= SWAP_ADDRESS_SPACE_SHIFT;
-		if (curr > end)
-			break;
-	}
-}
-
 /* 
  * If we are the only user, then try to free up the swap cache. 
  * 
@@ -465,7 +420,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		__SetPageLocked(new_page);
 		__SetPageSwapBacked(new_page);
 		err = add_to_swap_cache(new_page, entry,
-					gfp_mask & GFP_RECLAIM_MASK, NULL);
+					gfp_mask & GFP_RECLAIM_MASK);
 		if (likely(!err)) {
 			/* Initiate read into locked page */
 			SetPageWorkingset(new_page);

mm/swapfile.c

@@ -716,7 +716,6 @@ static void add_to_avail_list(struct swap_info_struct *p)
 static void swap_range_free(struct swap_info_struct *si, unsigned long offset,
 			    unsigned int nr_entries)
 {
-	unsigned long begin = offset;
 	unsigned long end = offset + nr_entries - 1;
 	void (*swap_slot_free_notify)(struct block_device *, unsigned long);
 
@@ -742,7 +741,6 @@ static void swap_range_free(struct swap_info_struct *si, unsigned long offset,
 			swap_slot_free_notify(si->bdev, offset);
 		offset++;
 	}
-	clear_shadow_from_swap_cache(si->type, begin, end);
 }
 
 static int scan_swap_map_slots(struct swap_info_struct *si,

mm/vmscan.c

@@ -965,7 +965,7 @@ 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, swap, NULL);
+		__delete_from_swap_cache(page, swap);
 		xa_unlock_irqrestore(&mapping->i_pages, flags);
 		put_swap_page(page, swap);
 	} else {