1 files changed, 0 insertions, 498 deletions
diff --git a/mm/frontswap.c b/mm/frontswap.c
deleted file mode 100644
index 157e5bf63504..000000000000
--- a/mm/frontswap.c
+++ /dev/null
@@ -1,498 +0,0 @@
-/*
- * Frontswap frontend
- *
- * This code provides the generic "frontend" layer to call a matching
- * "backend" driver implementation of frontswap.  See
- * Documentation/vm/frontswap.rst for more information.
- *
- * Copyright (C) 2009-2012 Oracle Corp.  All rights reserved.
- * Author: Dan Magenheimer
- *
- * This work is licensed under the terms of the GNU GPL, version 2.
- */
-
-#include <linux/mman.h>
-#include <linux/swap.h>
-#include <linux/swapops.h>
-#include <linux/security.h>
-#include <linux/module.h>
-#include <linux/debugfs.h>
-#include <linux/frontswap.h>
-#include <linux/swapfile.h>
-
-DEFINE_STATIC_KEY_FALSE(frontswap_enabled_key);
-
-/*
- * frontswap_ops are added by frontswap_register_ops, and provide the
- * frontswap "backend" implementation functions.  Multiple implementations
- * may be registered, but implementations can never deregister.  This
- * is a simple singly-linked list of all registered implementations.
- */
-static struct frontswap_ops *frontswap_ops __read_mostly;
-
-#define for_each_frontswap_ops(ops)		\
-	for ((ops) = frontswap_ops; (ops); (ops) = (ops)->next)
-
-/*
- * If enabled, frontswap_store will return failure even on success.  As
- * a result, the swap subsystem will always write the page to swap, in
- * effect converting frontswap into a writethrough cache.  In this mode,
- * there is no direct reduction in swap writes, but a frontswap backend
- * can unilaterally "reclaim" any pages in use with no data loss, thus
- * providing increases control over maximum memory usage due to frontswap.
- */
-static bool frontswap_writethrough_enabled __read_mostly;
-
-/*
- * If enabled, the underlying tmem implementation is capable of doing
- * exclusive gets, so frontswap_load, on a successful tmem_get must
- * mark the page as no longer in frontswap AND mark it dirty.
- */
-static bool frontswap_tmem_exclusive_gets_enabled __read_mostly;
-
-#ifdef CONFIG_DEBUG_FS
-/*
- * Counters available via /sys/kernel/debug/frontswap (if debugfs is
- * properly configured).  These are for information only so are not protected
- * against increment races.
- */
-static u64 frontswap_loads;
-static u64 frontswap_succ_stores;
-static u64 frontswap_failed_stores;
-static u64 frontswap_invalidates;
-
-static inline void inc_frontswap_loads(void) {
-	frontswap_loads++;
-}
-static inline void inc_frontswap_succ_stores(void) {
-	frontswap_succ_stores++;
-}
-static inline void inc_frontswap_failed_stores(void) {
-	frontswap_failed_stores++;
-}
-static inline void inc_frontswap_invalidates(void) {
-	frontswap_invalidates++;
-}
-#else
-static inline void inc_frontswap_loads(void) { }
-static inline void inc_frontswap_succ_stores(void) { }
-static inline void inc_frontswap_failed_stores(void) { }
-static inline void inc_frontswap_invalidates(void) { }
-#endif
-
-/*
- * Due to the asynchronous nature of the backends loading potentially
- * _after_ the swap system has been activated, we have chokepoints
- * on all frontswap functions to not call the backend until the backend
- * has registered.
- *
- * This would not guards us against the user deciding to call swapoff right as
- * we are calling the backend to initialize (so swapon is in action).
- * Fortunatly for us, the swapon_mutex has been taked by the callee so we are
- * OK. The other scenario where calls to frontswap_store (called via
- * swap_writepage) is racing with frontswap_invalidate_area (called via
- * swapoff) is again guarded by the swap subsystem.
- *
- * While no backend is registered all calls to frontswap_[store|load|
- * invalidate_area|invalidate_page] are ignored or fail.
- *
- * The time between the backend being registered and the swap file system
- * calling the backend (via the frontswap_* functions) is indeterminate as
- * frontswap_ops is not atomic_t (or a value guarded by a spinlock).
- * That is OK as we are comfortable missing some of these calls to the newly
- * registered backend.
- *
- * Obviously the opposite (unloading the backend) must be done after all
- * the frontswap_[store|load|invalidate_area|invalidate_page] start
- * ignoring or failing the requests.  However, there is currently no way
- * to unload a backend once it is registered.
- */
-
-/*
- * Register operations for frontswap
- */
-void frontswap_register_ops(struct frontswap_ops *ops)
-{
-	DECLARE_BITMAP(a, MAX_SWAPFILES);
-	DECLARE_BITMAP(b, MAX_SWAPFILES);
-	struct swap_info_struct *si;
-	unsigned int i;
-
-	bitmap_zero(a, MAX_SWAPFILES);
-	bitmap_zero(b, MAX_SWAPFILES);
-
-	spin_lock(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list) {
-		if (!WARN_ON(!si->frontswap_map))
-			set_bit(si->type, a);
-	}
-	spin_unlock(&swap_lock);
-
-	/* the new ops needs to know the currently active swap devices */
-	for_each_set_bit(i, a, MAX_SWAPFILES)
-		ops->init(i);
-
-	/*
-	 * Setting frontswap_ops must happen after the ops->init() calls
-	 * above; cmpxchg implies smp_mb() which will ensure the init is
-	 * complete at this point.
-	 */
-	do {
-		ops->next = frontswap_ops;
-	} while (cmpxchg(&frontswap_ops, ops->next, ops) != ops->next);
-
-	static_branch_inc(&frontswap_enabled_key);
-
-	spin_lock(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list) {
-		if (si->frontswap_map)
-			set_bit(si->type, b);
-	}
-	spin_unlock(&swap_lock);
-
-	/*
-	 * On the very unlikely chance that a swap device was added or
-	 * removed between setting the "a" list bits and the ops init
-	 * calls, we re-check and do init or invalidate for any changed
-	 * bits.
-	 */
-	if (unlikely(!bitmap_equal(a, b, MAX_SWAPFILES))) {
-		for (i = 0; i < MAX_SWAPFILES; i++) {
-			if (!test_bit(i, a) && test_bit(i, b))
-				ops->init(i);
-			else if (test_bit(i, a) && !test_bit(i, b))
-				ops->invalidate_area(i);
-		}
-	}
-}
-EXPORT_SYMBOL(frontswap_register_ops);
-
-/*
- * Enable/disable frontswap writethrough (see above).
- */
-void frontswap_writethrough(bool enable)
-{
-	frontswap_writethrough_enabled = enable;
-}
-EXPORT_SYMBOL(frontswap_writethrough);
-
-/*
- * Enable/disable frontswap exclusive gets (see above).
- */
-void frontswap_tmem_exclusive_gets(bool enable)
-{
-	frontswap_tmem_exclusive_gets_enabled = enable;
-}
-EXPORT_SYMBOL(frontswap_tmem_exclusive_gets);
-
-/*
- * Called when a swap device is swapon'd.
- */
-void __frontswap_init(unsigned type, unsigned long *map)
-{
-	struct swap_info_struct *sis = swap_info[type];
-	struct frontswap_ops *ops;
-
-	VM_BUG_ON(sis == NULL);
-
-	/*
-	 * p->frontswap is a bitmap that we MUST have to figure out which page
-	 * has gone in frontswap. Without it there is no point of continuing.
-	 */
-	if (WARN_ON(!map))
-		return;
-	/*
-	 * Irregardless of whether the frontswap backend has been loaded
-	 * before this function or it will be later, we _MUST_ have the
-	 * p->frontswap set to something valid to work properly.
-	 */
-	frontswap_map_set(sis, map);
-
-	for_each_frontswap_ops(ops)
-		ops->init(type);
-}
-EXPORT_SYMBOL(__frontswap_init);
-
-bool __frontswap_test(struct swap_info_struct *sis,
-				pgoff_t offset)
-{
-	if (sis->frontswap_map)
-		return test_bit(offset, sis->frontswap_map);
-	return false;
-}
-EXPORT_SYMBOL(__frontswap_test);
-
-static inline void __frontswap_set(struct swap_info_struct *sis,
-				   pgoff_t offset)
-{
-	set_bit(offset, sis->frontswap_map);
-	atomic_inc(&sis->frontswap_pages);
-}
-
-static inline void __frontswap_clear(struct swap_info_struct *sis,
-				     pgoff_t offset)
-{
-	clear_bit(offset, sis->frontswap_map);
-	atomic_dec(&sis->frontswap_pages);
-}
-
-/*
- * "Store" data from a page to frontswap and associate it with the page's
- * swaptype and offset.  Page must be locked and in the swap cache.
- * If frontswap already contains a page with matching swaptype and
- * offset, the frontswap implementation may either overwrite the data and
- * return success or invalidate the page from frontswap and return failure.
- */
-int __frontswap_store(struct page *page)
-{
-	int ret = -1;
-	swp_entry_t entry = { .val = page_private(page), };
-	int type = swp_type(entry);
-	struct swap_info_struct *sis = swap_info[type];
-	pgoff_t offset = swp_offset(entry);
-	struct frontswap_ops *ops;
-
-	VM_BUG_ON(!frontswap_ops);
-	VM_BUG_ON(!PageLocked(page));
-	VM_BUG_ON(sis == NULL);
-
-	/*
-	 * If a dup, we must remove the old page first; we can't leave the
-	 * old page no matter if the store of the new page succeeds or fails,
-	 * and we can't rely on the new page replacing the old page as we may
-	 * not store to the same implementation that contains the old page.
-	 */
-	if (__frontswap_test(sis, offset)) {
-		__frontswap_clear(sis, offset);
-		for_each_frontswap_ops(ops)
-			ops->invalidate_page(type, offset);
-	}
-
-	/* Try to store in each implementation, until one succeeds. */
-	for_each_frontswap_ops(ops) {
-		ret = ops->store(type, offset, page);
-		if (!ret) /* successful store */
-			break;
-	}
-	if (ret == 0) {
-		__frontswap_set(sis, offset);
-		inc_frontswap_succ_stores();
-	} else {
-		inc_frontswap_failed_stores();
-	}
-	if (frontswap_writethrough_enabled)
-		/* report failure so swap also writes to swap device */
-		ret = -1;
-	return ret;
-}
-EXPORT_SYMBOL(__frontswap_store);
-
-/*
- * "Get" data from frontswap associated with swaptype and offset that were
- * specified when the data was put to frontswap and use it to fill the
- * specified page with data. Page must be locked and in the swap cache.
- */
-int __frontswap_load(struct page *page)
-{
-	int ret = -1;
-	swp_entry_t entry = { .val = page_private(page), };
-	int type = swp_type(entry);
-	struct swap_info_struct *sis = swap_info[type];
-	pgoff_t offset = swp_offset(entry);
-	struct frontswap_ops *ops;
-
-	VM_BUG_ON(!frontswap_ops);
-	VM_BUG_ON(!PageLocked(page));
-	VM_BUG_ON(sis == NULL);
-
-	if (!__frontswap_test(sis, offset))
-		return -1;
-
-	/* Try loading from each implementation, until one succeeds. */
-	for_each_frontswap_ops(ops) {
-		ret = ops->load(type, offset, page);
-		if (!ret) /* successful load */
-			break;
-	}
-	if (ret == 0) {
-		inc_frontswap_loads();
-		if (frontswap_tmem_exclusive_gets_enabled) {
-			SetPageDirty(page);
-			__frontswap_clear(sis, offset);
-		}
-	}
-	return ret;
-}
-EXPORT_SYMBOL(__frontswap_load);
-
-/*
- * Invalidate any data from frontswap associated with the specified swaptype
- * and offset so that a subsequent "get" will fail.
- */
-void __frontswap_invalidate_page(unsigned type, pgoff_t offset)
-{
-	struct swap_info_struct *sis = swap_info[type];
-	struct frontswap_ops *ops;
-
-	VM_BUG_ON(!frontswap_ops);
-	VM_BUG_ON(sis == NULL);
-
-	if (!__frontswap_test(sis, offset))
-		return;
-
-	for_each_frontswap_ops(ops)
-		ops->invalidate_page(type, offset);
-	__frontswap_clear(sis, offset);
-	inc_frontswap_invalidates();
-}
-EXPORT_SYMBOL(__frontswap_invalidate_page);
-
-/*
- * Invalidate all data from frontswap associated with all offsets for the
- * specified swaptype.
- */
-void __frontswap_invalidate_area(unsigned type)
-{
-	struct swap_info_struct *sis = swap_info[type];
-	struct frontswap_ops *ops;
-
-	VM_BUG_ON(!frontswap_ops);
-	VM_BUG_ON(sis == NULL);
-
-	if (sis->frontswap_map == NULL)
-		return;
-
-	for_each_frontswap_ops(ops)
-		ops->invalidate_area(type);
-	atomic_set(&sis->frontswap_pages, 0);
-	bitmap_zero(sis->frontswap_map, sis->max);
-}
-EXPORT_SYMBOL(__frontswap_invalidate_area);
-
-static unsigned long __frontswap_curr_pages(void)
-{
-	unsigned long totalpages = 0;
-	struct swap_info_struct *si = NULL;
-
-	assert_spin_locked(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list)
-		totalpages += atomic_read(&si->frontswap_pages);
-	return totalpages;
-}
-
-static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused,
-					int *swapid)
-{
-	int ret = -EINVAL;
-	struct swap_info_struct *si = NULL;
-	int si_frontswap_pages;
-	unsigned long total_pages_to_unuse = total;
-	unsigned long pages = 0, pages_to_unuse = 0;
-
-	assert_spin_locked(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list) {
-		si_frontswap_pages = atomic_read(&si->frontswap_pages);
-		if (total_pages_to_unuse < si_frontswap_pages) {
-			pages = pages_to_unuse = total_pages_to_unuse;
-		} else {
-			pages = si_frontswap_pages;
-			pages_to_unuse = 0; /* unuse all */
-		}
-		/* ensure there is enough RAM to fetch pages from frontswap */
-		if (security_vm_enough_memory_mm(current->mm, pages)) {
-			ret = -ENOMEM;
-			continue;
-		}
-		vm_unacct_memory(pages);
-		*unused = pages_to_unuse;
-		*swapid = si->type;
-		ret = 0;
-		break;
-	}
-
-	return ret;
-}
-
-/*
- * Used to check if it's necessory and feasible to unuse pages.
- * Return 1 when nothing to do, 0 when need to shink pages,
- * error code when there is an error.
- */
-static int __frontswap_shrink(unsigned long target_pages,
-				unsigned long *pages_to_unuse,
-				int *type)
-{
-	unsigned long total_pages = 0, total_pages_to_unuse;
-
-	assert_spin_locked(&swap_lock);
-
-	total_pages = __frontswap_curr_pages();
-	if (total_pages <= target_pages) {
-		/* Nothing to do */
-		*pages_to_unuse = 0;
-		return 1;
-	}
-	total_pages_to_unuse = total_pages - target_pages;
-	return __frontswap_unuse_pages(total_pages_to_unuse, pages_to_unuse, type);
-}
-
-/*
- * Frontswap, like a true swap device, may unnecessarily retain pages
- * under certain circumstances; "shrink" frontswap is essentially a
- * "partial swapoff" and works by calling try_to_unuse to attempt to
- * unuse enough frontswap pages to attempt to -- subject to memory
- * constraints -- reduce the number of pages in frontswap to the
- * number given in the parameter target_pages.
- */
-void frontswap_shrink(unsigned long target_pages)
-{
-	unsigned long pages_to_unuse = 0;
-	int uninitialized_var(type), ret;
-
-	/*
-	 * we don't want to hold swap_lock while doing a very
-	 * lengthy try_to_unuse, but swap_list may change
-	 * so restart scan from swap_active_head each time
-	 */
-	spin_lock(&swap_lock);
-	ret = __frontswap_shrink(target_pages, &pages_to_unuse, &type);
-	spin_unlock(&swap_lock);
-	if (ret == 0)
-		try_to_unuse(type, true, pages_to_unuse);
-	return;
-}
-EXPORT_SYMBOL(frontswap_shrink);
-
-/*
- * Count and return the number of frontswap pages across all
- * swap devices.  This is exported so that backend drivers can
- * determine current usage without reading debugfs.
- */
-unsigned long frontswap_curr_pages(void)
-{
-	unsigned long totalpages = 0;
-
-	spin_lock(&swap_lock);
-	totalpages = __frontswap_curr_pages();
-	spin_unlock(&swap_lock);
-
-	return totalpages;
-}
-EXPORT_SYMBOL(frontswap_curr_pages);
-
-static int __init init_frontswap(void)
-{
-#ifdef CONFIG_DEBUG_FS
-	struct dentry *root = debugfs_create_dir("frontswap", NULL);
-	if (root == NULL)
-		return -ENXIO;
-	debugfs_create_u64("loads", 0444, root, &frontswap_loads);
-	debugfs_create_u64("succ_stores", 0444, root, &frontswap_succ_stores);
-	debugfs_create_u64("failed_stores", 0444, root,
-			   &frontswap_failed_stores);
-	debugfs_create_u64("invalidates", 0444, root, &frontswap_invalidates);
-#endif
-	return 0;
-}
-
-module_init(init_frontswap);