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mm/zswap.c
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/* * zswap.c - zswap driver file * * zswap is a backend for frontswap that takes pages that are in the process * of being swapped out and attempts to compress and store them in a * RAM-based memory pool. This can result in a significant I/O reduction on * the swap device and, in the case where decompressing from RAM is faster * than reading from the swap device, can also improve workload performance. * * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/cpu.h> #include <linux/highmem.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/types.h> #include <linux/atomic.h> #include <linux/frontswap.h> #include <linux/rbtree.h> #include <linux/swap.h> #include <linux/crypto.h> #include <linux/mempool.h> |
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#include <linux/zpool.h> |
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#include <linux/mm_types.h> #include <linux/page-flags.h> #include <linux/swapops.h> #include <linux/writeback.h> #include <linux/pagemap.h> /********************************* * statistics **********************************/ |
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/* Total bytes used by the compressed storage */ static u64 zswap_pool_total_size; |
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/* The number of compressed pages currently stored in zswap */ static atomic_t zswap_stored_pages = ATOMIC_INIT(0); /* * The statistics below are not protected from concurrent access for * performance reasons so they may not be a 100% accurate. However, * they do provide useful information on roughly how many times a * certain event is occurring. */ /* Pool limit was hit (see zswap_max_pool_percent) */ static u64 zswap_pool_limit_hit; /* Pages written back when pool limit was reached */ static u64 zswap_written_back_pages; /* Store failed due to a reclaim failure after pool limit was reached */ static u64 zswap_reject_reclaim_fail; /* Compressed page was too big for the allocator to (optimally) store */ static u64 zswap_reject_compress_poor; /* Store failed because underlying allocator could not get memory */ static u64 zswap_reject_alloc_fail; /* Store failed because the entry metadata could not be allocated (rare) */ static u64 zswap_reject_kmemcache_fail; /* Duplicate store was encountered (rare) */ static u64 zswap_duplicate_entry; /********************************* * tunables **********************************/ |
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/* Enable/disable zswap (disabled by default) */ static bool zswap_enabled; module_param_named(enabled, zswap_enabled, bool, 0644); |
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/* Crypto compressor to use */ |
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#define ZSWAP_COMPRESSOR_DEFAULT "lzo" |
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static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; |
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static int zswap_compressor_param_set(const char *, const struct kernel_param *); static struct kernel_param_ops zswap_compressor_param_ops = { .set = zswap_compressor_param_set, |
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.get = param_get_charp, .free = param_free_charp, |
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}; module_param_cb(compressor, &zswap_compressor_param_ops, |
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&zswap_compressor, 0644); |
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/* Compressed storage zpool to use */ |
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#define ZSWAP_ZPOOL_DEFAULT "zbud" |
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static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT; |
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static int zswap_zpool_param_set(const char *, const struct kernel_param *); static struct kernel_param_ops zswap_zpool_param_ops = { |
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.set = zswap_zpool_param_set, .get = param_get_charp, .free = param_free_charp, |
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}; |
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module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644); |
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/* The maximum percentage of memory that the compressed pool can occupy */ static unsigned int zswap_max_pool_percent = 20; module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644); |
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/********************************* |
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* data structures |
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**********************************/ |
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struct zswap_pool { struct zpool *zpool; struct crypto_comp * __percpu *tfm; struct kref kref; struct list_head list; struct rcu_head rcu_head; struct notifier_block notifier; char tfm_name[CRYPTO_MAX_ALG_NAME]; |
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}; |
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/* * struct zswap_entry * * This structure contains the metadata for tracking a single compressed * page within zswap. * * rbnode - links the entry into red-black tree for the appropriate swap type |
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* offset - the swap offset for the entry. Index into the red-black tree. |
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* refcount - the number of outstanding reference to the entry. This is needed * to protect against premature freeing of the entry by code |
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* concurrent calls to load, invalidate, and writeback. The lock |
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* for the zswap_tree structure that contains the entry must * be held while changing the refcount. Since the lock must * be held, there is no reason to also make refcount atomic. |
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* length - the length in bytes of the compressed page data. Needed during |
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* decompression |
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* pool - the zswap_pool the entry's data is in * handle - zpool allocation handle that stores the compressed page data |
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*/ struct zswap_entry { struct rb_node rbnode; pgoff_t offset; int refcount; unsigned int length; |
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struct zswap_pool *pool; |
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unsigned long handle; }; struct zswap_header { swp_entry_t swpentry; }; /* * The tree lock in the zswap_tree struct protects a few things: * - the rbtree * - the refcount field of each entry in the tree */ struct zswap_tree { struct rb_root rbroot; spinlock_t lock; |
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}; static struct zswap_tree *zswap_trees[MAX_SWAPFILES]; |
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/* RCU-protected iteration */ static LIST_HEAD(zswap_pools); /* protects zswap_pools list modification */ static DEFINE_SPINLOCK(zswap_pools_lock); |
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/* pool counter to provide unique names to zpool */ static atomic_t zswap_pools_count = ATOMIC_INIT(0); |
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/* used by param callback function */ static bool zswap_init_started; |
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/********************************* * helpers and fwd declarations **********************************/ #define zswap_pool_debug(msg, p) \ pr_debug("%s pool %s/%s ", msg, (p)->tfm_name, \ zpool_get_type((p)->zpool)) static int zswap_writeback_entry(struct zpool *pool, unsigned long handle); static int zswap_pool_get(struct zswap_pool *pool); static void zswap_pool_put(struct zswap_pool *pool); static const struct zpool_ops zswap_zpool_ops = { .evict = zswap_writeback_entry }; static bool zswap_is_full(void) { return totalram_pages * zswap_max_pool_percent / 100 < DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE); } static void zswap_update_total_size(void) { struct zswap_pool *pool; u64 total = 0; rcu_read_lock(); list_for_each_entry_rcu(pool, &zswap_pools, list) total += zpool_get_total_size(pool->zpool); rcu_read_unlock(); zswap_pool_total_size = total; } |
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/********************************* * zswap entry functions **********************************/ static struct kmem_cache *zswap_entry_cache; |
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static int __init zswap_entry_cache_create(void) |
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{ zswap_entry_cache = KMEM_CACHE(zswap_entry, 0); |
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return zswap_entry_cache == NULL; |
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} |
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static void __init zswap_entry_cache_destroy(void) |
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{ kmem_cache_destroy(zswap_entry_cache); } static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp) { struct zswap_entry *entry; entry = kmem_cache_alloc(zswap_entry_cache, gfp); if (!entry) return NULL; entry->refcount = 1; |
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RB_CLEAR_NODE(&entry->rbnode); |
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return entry; } static void zswap_entry_cache_free(struct zswap_entry *entry) { kmem_cache_free(zswap_entry_cache, entry); } |
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/********************************* * rbtree functions **********************************/ static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset) { struct rb_node *node = root->rb_node; struct zswap_entry *entry; while (node) { entry = rb_entry(node, struct zswap_entry, rbnode); if (entry->offset > offset) node = node->rb_left; else if (entry->offset < offset) node = node->rb_right; else return entry; } return NULL; } /* * In the case that a entry with the same offset is found, a pointer to * the existing entry is stored in dupentry and the function returns -EEXIST */ static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry, struct zswap_entry **dupentry) { struct rb_node **link = &root->rb_node, *parent = NULL; struct zswap_entry *myentry; while (*link) { parent = *link; myentry = rb_entry(parent, struct zswap_entry, rbnode); if (myentry->offset > entry->offset) link = &(*link)->rb_left; else if (myentry->offset < entry->offset) link = &(*link)->rb_right; else { *dupentry = myentry; return -EEXIST; } } rb_link_node(&entry->rbnode, parent, link); rb_insert_color(&entry->rbnode, root); return 0; } |
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static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry) { if (!RB_EMPTY_NODE(&entry->rbnode)) { rb_erase(&entry->rbnode, root); RB_CLEAR_NODE(&entry->rbnode); } } /* |
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* Carries out the common pattern of freeing and entry's zpool allocation, |
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* freeing the entry itself, and decrementing the number of stored pages. */ |
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static void zswap_free_entry(struct zswap_entry *entry) |
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{ |
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zpool_free(entry->pool->zpool, entry->handle); zswap_pool_put(entry->pool); |
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zswap_entry_cache_free(entry); atomic_dec(&zswap_stored_pages); |
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zswap_update_total_size(); |
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} /* caller must hold the tree lock */ static void zswap_entry_get(struct zswap_entry *entry) { entry->refcount++; } /* caller must hold the tree lock * remove from the tree and free it, if nobody reference the entry */ static void zswap_entry_put(struct zswap_tree *tree, struct zswap_entry *entry) { int refcount = --entry->refcount; BUG_ON(refcount < 0); if (refcount == 0) { zswap_rb_erase(&tree->rbroot, entry); |
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zswap_free_entry(entry); |
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} } /* caller must hold the tree lock */ static struct zswap_entry *zswap_entry_find_get(struct rb_root *root, pgoff_t offset) { |
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struct zswap_entry *entry; |
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entry = zswap_rb_search(root, offset); if (entry) zswap_entry_get(entry); return entry; } |
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/********************************* * per-cpu code **********************************/ static DEFINE_PER_CPU(u8 *, zswap_dstmem); |
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static int __zswap_cpu_dstmem_notifier(unsigned long action, unsigned long cpu) |
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{ |
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u8 *dst; switch (action) { case CPU_UP_PREPARE: |
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dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); |
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if (!dst) { pr_err("can't allocate compressor buffer "); |
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return NOTIFY_BAD; } per_cpu(zswap_dstmem, cpu) = dst; break; case CPU_DEAD: case CPU_UP_CANCELED: |
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dst = per_cpu(zswap_dstmem, cpu); kfree(dst); per_cpu(zswap_dstmem, cpu) = NULL; break; default: break; } return NOTIFY_OK; } |
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static int zswap_cpu_dstmem_notifier(struct notifier_block *nb, unsigned long action, void *pcpu) |
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{ |
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return __zswap_cpu_dstmem_notifier(action, (unsigned long)pcpu); |
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} |
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static struct notifier_block zswap_dstmem_notifier = { .notifier_call = zswap_cpu_dstmem_notifier, |
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}; |
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static int __init zswap_cpu_dstmem_init(void) { unsigned long cpu; cpu_notifier_register_begin(); for_each_online_cpu(cpu) if (__zswap_cpu_dstmem_notifier(CPU_UP_PREPARE, cpu) == NOTIFY_BAD) goto cleanup; __register_cpu_notifier(&zswap_dstmem_notifier); cpu_notifier_register_done(); return 0; cleanup: for_each_online_cpu(cpu) __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu); cpu_notifier_register_done(); return -ENOMEM; } static void zswap_cpu_dstmem_destroy(void) { unsigned long cpu; cpu_notifier_register_begin(); for_each_online_cpu(cpu) __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu); __unregister_cpu_notifier(&zswap_dstmem_notifier); cpu_notifier_register_done(); } static int __zswap_cpu_comp_notifier(struct zswap_pool *pool, unsigned long action, unsigned long cpu) { struct crypto_comp *tfm; switch (action) { case CPU_UP_PREPARE: if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu))) break; tfm = crypto_alloc_comp(pool->tfm_name, 0, 0); if (IS_ERR_OR_NULL(tfm)) { pr_err("could not alloc crypto comp %s : %ld ", pool->tfm_name, PTR_ERR(tfm)); return NOTIFY_BAD; } *per_cpu_ptr(pool->tfm, cpu) = tfm; break; case CPU_DEAD: case CPU_UP_CANCELED: tfm = *per_cpu_ptr(pool->tfm, cpu); if (!IS_ERR_OR_NULL(tfm)) crypto_free_comp(tfm); *per_cpu_ptr(pool->tfm, cpu) = NULL; break; default: break; } return NOTIFY_OK; } static int zswap_cpu_comp_notifier(struct notifier_block *nb, unsigned long action, void *pcpu) { unsigned long cpu = (unsigned long)pcpu; struct zswap_pool *pool = container_of(nb, typeof(*pool), notifier); return __zswap_cpu_comp_notifier(pool, action, cpu); } static int zswap_cpu_comp_init(struct zswap_pool *pool) |
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{ unsigned long cpu; |
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memset(&pool->notifier, 0, sizeof(pool->notifier)); pool->notifier.notifier_call = zswap_cpu_comp_notifier; |
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cpu_notifier_register_begin(); |
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for_each_online_cpu(cpu) |
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if (__zswap_cpu_comp_notifier(pool, CPU_UP_PREPARE, cpu) == NOTIFY_BAD) |
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goto cleanup; |
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__register_cpu_notifier(&pool->notifier); |
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cpu_notifier_register_done(); |
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return 0; cleanup: for_each_online_cpu(cpu) |
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__zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu); |
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cpu_notifier_register_done(); |
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return -ENOMEM; } |
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static void zswap_cpu_comp_destroy(struct zswap_pool *pool) { unsigned long cpu; cpu_notifier_register_begin(); for_each_online_cpu(cpu) __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu); __unregister_cpu_notifier(&pool->notifier); cpu_notifier_register_done(); } |
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/********************************* |
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* pool functions |
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**********************************/ |
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static struct zswap_pool *__zswap_pool_current(void) |
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{ |
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struct zswap_pool *pool; pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list); WARN_ON(!pool); return pool; } static struct zswap_pool *zswap_pool_current(void) { assert_spin_locked(&zswap_pools_lock); return __zswap_pool_current(); } static struct zswap_pool *zswap_pool_current_get(void) { struct zswap_pool *pool; rcu_read_lock(); pool = __zswap_pool_current(); if (!pool || !zswap_pool_get(pool)) pool = NULL; rcu_read_unlock(); return pool; } static struct zswap_pool *zswap_pool_last_get(void) { struct zswap_pool *pool, *last = NULL; rcu_read_lock(); list_for_each_entry_rcu(pool, &zswap_pools, list) last = pool; if (!WARN_ON(!last) && !zswap_pool_get(last)) last = NULL; rcu_read_unlock(); return last; } |
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/* type and compressor must be null-terminated */ |
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static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor) { struct zswap_pool *pool; assert_spin_locked(&zswap_pools_lock); list_for_each_entry_rcu(pool, &zswap_pools, list) { |
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if (strcmp(pool->tfm_name, compressor)) |
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continue; |
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if (strcmp(zpool_get_type(pool->zpool), type)) |
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continue; /* if we can't get it, it's about to be destroyed */ if (!zswap_pool_get(pool)) continue; return pool; } return NULL; } static struct zswap_pool *zswap_pool_create(char *type, char *compressor) { struct zswap_pool *pool; |
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char name[38]; /* 'zswap' + 32 char (max) num + \0 */ |
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gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; |
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pool = kzalloc(sizeof(*pool), GFP_KERNEL); if (!pool) { pr_err("pool alloc failed "); return NULL; } |
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/* unique name for each pool specifically required by zsmalloc */ snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count)); pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops); |
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if (!pool->zpool) { pr_err("%s zpool not available ", type); goto error; } pr_debug("using %s zpool ", zpool_get_type(pool->zpool)); strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name)); pool->tfm = alloc_percpu(struct crypto_comp *); if (!pool->tfm) { pr_err("percpu alloc failed "); goto error; } if (zswap_cpu_comp_init(pool)) goto error; pr_debug("using %s compressor ", pool->tfm_name); /* being the current pool takes 1 ref; this func expects the * caller to always add the new pool as the current pool */ kref_init(&pool->kref); INIT_LIST_HEAD(&pool->list); zswap_pool_debug("created", pool); return pool; error: free_percpu(pool->tfm); if (pool->zpool) zpool_destroy_pool(pool->zpool); kfree(pool); return NULL; } |
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static __init struct zswap_pool *__zswap_pool_create_fallback(void) |
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{ if (!crypto_has_comp(zswap_compressor, 0, 0)) { |
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if (!strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) { pr_err("default compressor %s not available ", zswap_compressor); return NULL; } |
f1c54846e zswap: dynamic po... |
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pr_err("compressor %s not available, using default %s ", zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT); |
c99b42c35 zswap: use charp ... |
618 619 |
param_free_charp(&zswap_compressor); zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; |
f1c54846e zswap: dynamic po... |
620 621 |
} if (!zpool_has_pool(zswap_zpool_type)) { |
c99b42c35 zswap: use charp ... |
622 623 624 625 626 627 |
if (!strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) { pr_err("default zpool %s not available ", zswap_zpool_type); return NULL; } |
f1c54846e zswap: dynamic po... |
628 629 630 |
pr_err("zpool %s not available, using default %s ", zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT); |
c99b42c35 zswap: use charp ... |
631 632 |
param_free_charp(&zswap_zpool_type); zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT; |
f1c54846e zswap: dynamic po... |
633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 |
} return zswap_pool_create(zswap_zpool_type, zswap_compressor); } static void zswap_pool_destroy(struct zswap_pool *pool) { zswap_pool_debug("destroying", pool); zswap_cpu_comp_destroy(pool); free_percpu(pool->tfm); zpool_destroy_pool(pool->zpool); kfree(pool); } static int __must_check zswap_pool_get(struct zswap_pool *pool) { return kref_get_unless_zero(&pool->kref); } static void __zswap_pool_release(struct rcu_head *head) { struct zswap_pool *pool = container_of(head, typeof(*pool), rcu_head); /* nobody should have been able to get a kref... */ WARN_ON(kref_get_unless_zero(&pool->kref)); /* pool is now off zswap_pools list and has no references. */ zswap_pool_destroy(pool); } static void __zswap_pool_empty(struct kref *kref) { struct zswap_pool *pool; pool = container_of(kref, typeof(*pool), kref); spin_lock(&zswap_pools_lock); WARN_ON(pool == zswap_pool_current()); list_del_rcu(&pool->list); call_rcu(&pool->rcu_head, __zswap_pool_release); spin_unlock(&zswap_pools_lock); } static void zswap_pool_put(struct zswap_pool *pool) { kref_put(&pool->kref, __zswap_pool_empty); |
2b2811178 zswap: add to mm/ |
683 |
} |
2b2811178 zswap: add to mm/ |
684 |
/********************************* |
90b0fc26d zswap: change zpo... |
685 686 |
* param callbacks **********************************/ |
c99b42c35 zswap: use charp ... |
687 |
/* val must be a null-terminated string */ |
90b0fc26d zswap: change zpo... |
688 689 690 691 |
static int __zswap_param_set(const char *val, const struct kernel_param *kp, char *type, char *compressor) { struct zswap_pool *pool, *put_pool = NULL; |
c99b42c35 zswap: use charp ... |
692 |
char *s = strstrip((char *)val); |
90b0fc26d zswap: change zpo... |
693 |
int ret; |
c99b42c35 zswap: use charp ... |
694 695 696 |
/* no change required */ if (!strcmp(s, *(char **)kp->arg)) return 0; |
90b0fc26d zswap: change zpo... |
697 698 699 700 701 |
/* if this is load-time (pre-init) param setting, * don't create a pool; that's done during init. */ if (!zswap_init_started) |
c99b42c35 zswap: use charp ... |
702 |
return param_set_charp(s, kp); |
90b0fc26d zswap: change zpo... |
703 704 |
if (!type) { |
c99b42c35 zswap: use charp ... |
705 706 707 |
if (!zpool_has_pool(s)) { pr_err("zpool %s not available ", s); |
90b0fc26d zswap: change zpo... |
708 709 |
return -ENOENT; } |
c99b42c35 zswap: use charp ... |
710 |
type = s; |
90b0fc26d zswap: change zpo... |
711 |
} else if (!compressor) { |
c99b42c35 zswap: use charp ... |
712 713 714 |
if (!crypto_has_comp(s, 0, 0)) { pr_err("compressor %s not available ", s); |
90b0fc26d zswap: change zpo... |
715 716 |
return -ENOENT; } |
c99b42c35 zswap: use charp ... |
717 718 719 720 |
compressor = s; } else { WARN_ON(1); return -EINVAL; |
90b0fc26d zswap: change zpo... |
721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 |
} spin_lock(&zswap_pools_lock); pool = zswap_pool_find_get(type, compressor); if (pool) { zswap_pool_debug("using existing", pool); list_del_rcu(&pool->list); } else { spin_unlock(&zswap_pools_lock); pool = zswap_pool_create(type, compressor); spin_lock(&zswap_pools_lock); } if (pool) |
c99b42c35 zswap: use charp ... |
736 |
ret = param_set_charp(s, kp); |
90b0fc26d zswap: change zpo... |
737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 |
else ret = -EINVAL; if (!ret) { put_pool = zswap_pool_current(); list_add_rcu(&pool->list, &zswap_pools); } else if (pool) { /* add the possibly pre-existing pool to the end of the pools * list; if it's new (and empty) then it'll be removed and * destroyed by the put after we drop the lock */ list_add_tail_rcu(&pool->list, &zswap_pools); put_pool = pool; } spin_unlock(&zswap_pools_lock); /* drop the ref from either the old current pool, * or the new pool we failed to add */ if (put_pool) zswap_pool_put(put_pool); return ret; } static int zswap_compressor_param_set(const char *val, const struct kernel_param *kp) { return __zswap_param_set(val, kp, zswap_zpool_type, NULL); } static int zswap_zpool_param_set(const char *val, const struct kernel_param *kp) { return __zswap_param_set(val, kp, NULL, zswap_compressor); } /********************************* |
2b2811178 zswap: add to mm/ |
776 777 778 779 780 781 |
* writeback code **********************************/ /* return enum for zswap_get_swap_cache_page */ enum zswap_get_swap_ret { ZSWAP_SWAPCACHE_NEW, ZSWAP_SWAPCACHE_EXIST, |
67d13fe84 mm/zswap: bugfix:... |
782 |
ZSWAP_SWAPCACHE_FAIL, |
2b2811178 zswap: add to mm/ |
783 784 785 786 787 788 789 790 791 792 793 794 795 |
}; /* * zswap_get_swap_cache_page * * This is an adaption of read_swap_cache_async() * * This function tries to find a page with the given swap entry * in the swapper_space address space (the swap cache). If the page * is found, it is returned in retpage. Otherwise, a page is allocated, * added to the swap cache, and returned in retpage. * * If success, the swap cache page is returned in retpage |
67d13fe84 mm/zswap: bugfix:... |
796 797 798 799 |
* Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated, * the new page is added to swapcache and locked * Returns ZSWAP_SWAPCACHE_FAIL on error |
2b2811178 zswap: add to mm/ |
800 801 802 803 |
*/ static int zswap_get_swap_cache_page(swp_entry_t entry, struct page **retpage) { |
5b999aadb mm: swap: zswap: ... |
804 |
bool page_was_allocated; |
2b2811178 zswap: add to mm/ |
805 |
|
5b999aadb mm: swap: zswap: ... |
806 807 808 809 810 |
*retpage = __read_swap_cache_async(entry, GFP_KERNEL, NULL, 0, &page_was_allocated); if (page_was_allocated) return ZSWAP_SWAPCACHE_NEW; if (!*retpage) |
67d13fe84 mm/zswap: bugfix:... |
811 |
return ZSWAP_SWAPCACHE_FAIL; |
2b2811178 zswap: add to mm/ |
812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 |
return ZSWAP_SWAPCACHE_EXIST; } /* * Attempts to free an entry by adding a page to the swap cache, * decompressing the entry data into the page, and issuing a * bio write to write the page back to the swap device. * * This can be thought of as a "resumed writeback" of the page * to the swap device. We are basically resuming the same swap * writeback path that was intercepted with the frontswap_store() * in the first place. After the page has been decompressed into * the swap cache, the compressed version stored by zswap can be * freed. */ |
12d79d64b mm/zpool: update ... |
827 |
static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) |
2b2811178 zswap: add to mm/ |
828 829 830 831 832 833 834 |
{ struct zswap_header *zhdr; swp_entry_t swpentry; struct zswap_tree *tree; pgoff_t offset; struct zswap_entry *entry; struct page *page; |
f1c54846e zswap: dynamic po... |
835 |
struct crypto_comp *tfm; |
2b2811178 zswap: add to mm/ |
836 837 |
u8 *src, *dst; unsigned int dlen; |
0ab0abcf5 mm/zswap: refacto... |
838 |
int ret; |
2b2811178 zswap: add to mm/ |
839 840 841 842 843 |
struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, }; /* extract swpentry from data */ |
12d79d64b mm/zpool: update ... |
844 |
zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO); |
2b2811178 zswap: add to mm/ |
845 |
swpentry = zhdr->swpentry; /* here */ |
12d79d64b mm/zpool: update ... |
846 |
zpool_unmap_handle(pool, handle); |
2b2811178 zswap: add to mm/ |
847 848 |
tree = zswap_trees[swp_type(swpentry)]; offset = swp_offset(swpentry); |
2b2811178 zswap: add to mm/ |
849 850 851 |
/* find and ref zswap entry */ spin_lock(&tree->lock); |
0ab0abcf5 mm/zswap: refacto... |
852 |
entry = zswap_entry_find_get(&tree->rbroot, offset); |
2b2811178 zswap: add to mm/ |
853 854 855 856 857 |
if (!entry) { /* entry was invalidated */ spin_unlock(&tree->lock); return 0; } |
2b2811178 zswap: add to mm/ |
858 859 860 861 862 |
spin_unlock(&tree->lock); BUG_ON(offset != entry->offset); /* try to allocate swap cache page */ switch (zswap_get_swap_cache_page(swpentry, &page)) { |
67d13fe84 mm/zswap: bugfix:... |
863 |
case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */ |
2b2811178 zswap: add to mm/ |
864 865 |
ret = -ENOMEM; goto fail; |
67d13fe84 mm/zswap: bugfix:... |
866 |
case ZSWAP_SWAPCACHE_EXIST: |
2b2811178 zswap: add to mm/ |
867 |
/* page is already in the swap cache, ignore for now */ |
09cbfeaf1 mm, fs: get rid o... |
868 |
put_page(page); |
2b2811178 zswap: add to mm/ |
869 870 871 872 873 874 |
ret = -EEXIST; goto fail; case ZSWAP_SWAPCACHE_NEW: /* page is locked */ /* decompress */ dlen = PAGE_SIZE; |
f1c54846e zswap: dynamic po... |
875 |
src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle, |
12d79d64b mm/zpool: update ... |
876 |
ZPOOL_MM_RO) + sizeof(struct zswap_header); |
2b2811178 zswap: add to mm/ |
877 |
dst = kmap_atomic(page); |
f1c54846e zswap: dynamic po... |
878 879 880 881 |
tfm = *get_cpu_ptr(entry->pool->tfm); ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen); put_cpu_ptr(entry->pool->tfm); |
2b2811178 zswap: add to mm/ |
882 |
kunmap_atomic(dst); |
f1c54846e zswap: dynamic po... |
883 |
zpool_unmap_handle(entry->pool->zpool, entry->handle); |
2b2811178 zswap: add to mm/ |
884 885 886 887 888 889 |
BUG_ON(ret); BUG_ON(dlen != PAGE_SIZE); /* page is up to date */ SetPageUptodate(page); } |
b349acc76 mm/zswap: avoid u... |
890 891 |
/* move it to the tail of the inactive list after end_writeback */ SetPageReclaim(page); |
2b2811178 zswap: add to mm/ |
892 893 |
/* start writeback */ __swap_writepage(page, &wbc, end_swap_bio_write); |
09cbfeaf1 mm, fs: get rid o... |
894 |
put_page(page); |
2b2811178 zswap: add to mm/ |
895 896 897 |
zswap_written_back_pages++; spin_lock(&tree->lock); |
2b2811178 zswap: add to mm/ |
898 |
/* drop local reference */ |
0ab0abcf5 mm/zswap: refacto... |
899 |
zswap_entry_put(tree, entry); |
2b2811178 zswap: add to mm/ |
900 901 |
/* |
0ab0abcf5 mm/zswap: refacto... |
902 903 904 905 906 907 908 909 |
* There are two possible situations for entry here: * (1) refcount is 1(normal case), entry is valid and on the tree * (2) refcount is 0, entry is freed and not on the tree * because invalidate happened during writeback * search the tree and free the entry if find entry */ if (entry == zswap_rb_search(&tree->rbroot, offset)) zswap_entry_put(tree, entry); |
2b2811178 zswap: add to mm/ |
910 |
spin_unlock(&tree->lock); |
2b2811178 zswap: add to mm/ |
911 |
|
0ab0abcf5 mm/zswap: refacto... |
912 913 914 915 916 917 918 919 920 |
goto end; /* * if we get here due to ZSWAP_SWAPCACHE_EXIST * a load may happening concurrently * it is safe and okay to not free the entry * if we free the entry in the following put * it it either okay to return !0 */ |
2b2811178 zswap: add to mm/ |
921 922 |
fail: spin_lock(&tree->lock); |
0ab0abcf5 mm/zswap: refacto... |
923 |
zswap_entry_put(tree, entry); |
2b2811178 zswap: add to mm/ |
924 |
spin_unlock(&tree->lock); |
0ab0abcf5 mm/zswap: refacto... |
925 926 |
end: |
2b2811178 zswap: add to mm/ |
927 928 |
return ret; } |
f1c54846e zswap: dynamic po... |
929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 |
static int zswap_shrink(void) { struct zswap_pool *pool; int ret; pool = zswap_pool_last_get(); if (!pool) return -ENOENT; ret = zpool_shrink(pool->zpool, 1, NULL); zswap_pool_put(pool); return ret; } |
2b2811178 zswap: add to mm/ |
944 945 946 947 948 949 950 951 952 |
/********************************* * frontswap hooks **********************************/ /* attempts to compress and store an single page */ static int zswap_frontswap_store(unsigned type, pgoff_t offset, struct page *page) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry, *dupentry; |
f1c54846e zswap: dynamic po... |
953 |
struct crypto_comp *tfm; |
2b2811178 zswap: add to mm/ |
954 955 956 957 958 959 |
int ret; unsigned int dlen = PAGE_SIZE, len; unsigned long handle; char *buf; u8 *src, *dst; struct zswap_header *zhdr; |
c00ed16a9 zswap: runtime en... |
960 |
if (!zswap_enabled || !tree) { |
2b2811178 zswap: add to mm/ |
961 962 963 964 965 966 967 |
ret = -ENODEV; goto reject; } /* reclaim space if needed */ if (zswap_is_full()) { zswap_pool_limit_hit++; |
f1c54846e zswap: dynamic po... |
968 |
if (zswap_shrink()) { |
2b2811178 zswap: add to mm/ |
969 970 971 972 973 974 975 976 977 978 979 980 981 |
zswap_reject_reclaim_fail++; ret = -ENOMEM; goto reject; } } /* allocate entry */ entry = zswap_entry_cache_alloc(GFP_KERNEL); if (!entry) { zswap_reject_kmemcache_fail++; ret = -ENOMEM; goto reject; } |
f1c54846e zswap: dynamic po... |
982 983 984 985 986 987 |
/* if entry is successfully added, it keeps the reference */ entry->pool = zswap_pool_current_get(); if (!entry->pool) { ret = -EINVAL; goto freepage; } |
2b2811178 zswap: add to mm/ |
988 989 |
/* compress */ dst = get_cpu_var(zswap_dstmem); |
f1c54846e zswap: dynamic po... |
990 |
tfm = *get_cpu_ptr(entry->pool->tfm); |
2b2811178 zswap: add to mm/ |
991 |
src = kmap_atomic(page); |
f1c54846e zswap: dynamic po... |
992 |
ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen); |
2b2811178 zswap: add to mm/ |
993 |
kunmap_atomic(src); |
f1c54846e zswap: dynamic po... |
994 |
put_cpu_ptr(entry->pool->tfm); |
2b2811178 zswap: add to mm/ |
995 996 |
if (ret) { ret = -EINVAL; |
f1c54846e zswap: dynamic po... |
997 |
goto put_dstmem; |
2b2811178 zswap: add to mm/ |
998 999 1000 1001 |
} /* store */ len = dlen + sizeof(struct zswap_header); |
f1c54846e zswap: dynamic po... |
1002 |
ret = zpool_malloc(entry->pool->zpool, len, |
d0164adc8 mm, page_alloc: d... |
1003 1004 |
__GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM, &handle); |
2b2811178 zswap: add to mm/ |
1005 1006 |
if (ret == -ENOSPC) { zswap_reject_compress_poor++; |
f1c54846e zswap: dynamic po... |
1007 |
goto put_dstmem; |
2b2811178 zswap: add to mm/ |
1008 1009 1010 |
} if (ret) { zswap_reject_alloc_fail++; |
f1c54846e zswap: dynamic po... |
1011 |
goto put_dstmem; |
2b2811178 zswap: add to mm/ |
1012 |
} |
f1c54846e zswap: dynamic po... |
1013 |
zhdr = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW); |
2b2811178 zswap: add to mm/ |
1014 1015 1016 |
zhdr->swpentry = swp_entry(type, offset); buf = (u8 *)(zhdr + 1); memcpy(buf, dst, dlen); |
f1c54846e zswap: dynamic po... |
1017 |
zpool_unmap_handle(entry->pool->zpool, handle); |
2b2811178 zswap: add to mm/ |
1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 |
put_cpu_var(zswap_dstmem); /* populate entry */ entry->offset = offset; entry->handle = handle; entry->length = dlen; /* map */ spin_lock(&tree->lock); do { ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry); if (ret == -EEXIST) { zswap_duplicate_entry++; /* remove from rbtree */ |
0ab0abcf5 mm/zswap: refacto... |
1032 1033 |
zswap_rb_erase(&tree->rbroot, dupentry); zswap_entry_put(tree, dupentry); |
2b2811178 zswap: add to mm/ |
1034 1035 1036 1037 1038 1039 |
} } while (ret == -EEXIST); spin_unlock(&tree->lock); /* update stats */ atomic_inc(&zswap_stored_pages); |
f1c54846e zswap: dynamic po... |
1040 |
zswap_update_total_size(); |
2b2811178 zswap: add to mm/ |
1041 1042 |
return 0; |
f1c54846e zswap: dynamic po... |
1043 |
put_dstmem: |
2b2811178 zswap: add to mm/ |
1044 |
put_cpu_var(zswap_dstmem); |
f1c54846e zswap: dynamic po... |
1045 1046 |
zswap_pool_put(entry->pool); freepage: |
2b2811178 zswap: add to mm/ |
1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 |
zswap_entry_cache_free(entry); reject: return ret; } /* * returns 0 if the page was successfully decompressed * return -1 on entry not found or error */ static int zswap_frontswap_load(unsigned type, pgoff_t offset, struct page *page) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry; |
f1c54846e zswap: dynamic po... |
1061 |
struct crypto_comp *tfm; |
2b2811178 zswap: add to mm/ |
1062 1063 |
u8 *src, *dst; unsigned int dlen; |
0ab0abcf5 mm/zswap: refacto... |
1064 |
int ret; |
2b2811178 zswap: add to mm/ |
1065 1066 1067 |
/* find */ spin_lock(&tree->lock); |
0ab0abcf5 mm/zswap: refacto... |
1068 |
entry = zswap_entry_find_get(&tree->rbroot, offset); |
2b2811178 zswap: add to mm/ |
1069 1070 1071 1072 1073 |
if (!entry) { /* entry was written back */ spin_unlock(&tree->lock); return -1; } |
2b2811178 zswap: add to mm/ |
1074 1075 1076 1077 |
spin_unlock(&tree->lock); /* decompress */ dlen = PAGE_SIZE; |
f1c54846e zswap: dynamic po... |
1078 |
src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle, |
12d79d64b mm/zpool: update ... |
1079 |
ZPOOL_MM_RO) + sizeof(struct zswap_header); |
2b2811178 zswap: add to mm/ |
1080 |
dst = kmap_atomic(page); |
f1c54846e zswap: dynamic po... |
1081 1082 1083 |
tfm = *get_cpu_ptr(entry->pool->tfm); ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen); put_cpu_ptr(entry->pool->tfm); |
2b2811178 zswap: add to mm/ |
1084 |
kunmap_atomic(dst); |
f1c54846e zswap: dynamic po... |
1085 |
zpool_unmap_handle(entry->pool->zpool, entry->handle); |
2b2811178 zswap: add to mm/ |
1086 1087 1088 |
BUG_ON(ret); spin_lock(&tree->lock); |
0ab0abcf5 mm/zswap: refacto... |
1089 |
zswap_entry_put(tree, entry); |
2b2811178 zswap: add to mm/ |
1090 |
spin_unlock(&tree->lock); |
2b2811178 zswap: add to mm/ |
1091 1092 1093 1094 1095 1096 1097 1098 |
return 0; } /* frees an entry in zswap */ static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry; |
2b2811178 zswap: add to mm/ |
1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 |
/* find */ spin_lock(&tree->lock); entry = zswap_rb_search(&tree->rbroot, offset); if (!entry) { /* entry was written back */ spin_unlock(&tree->lock); return; } /* remove from rbtree */ |
0ab0abcf5 mm/zswap: refacto... |
1110 |
zswap_rb_erase(&tree->rbroot, entry); |
2b2811178 zswap: add to mm/ |
1111 1112 |
/* drop the initial reference from entry creation */ |
0ab0abcf5 mm/zswap: refacto... |
1113 |
zswap_entry_put(tree, entry); |
2b2811178 zswap: add to mm/ |
1114 1115 |
spin_unlock(&tree->lock); |
2b2811178 zswap: add to mm/ |
1116 1117 1118 1119 1120 1121 |
} /* frees all zswap entries for the given swap type */ static void zswap_frontswap_invalidate_area(unsigned type) { struct zswap_tree *tree = zswap_trees[type]; |
0bd42136f mm/zswap: use pos... |
1122 |
struct zswap_entry *entry, *n; |
2b2811178 zswap: add to mm/ |
1123 1124 1125 1126 1127 1128 |
if (!tree) return; /* walk the tree and free everything */ spin_lock(&tree->lock); |
0ab0abcf5 mm/zswap: refacto... |
1129 |
rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode) |
60105e124 mm/zswap: support... |
1130 |
zswap_free_entry(entry); |
2b2811178 zswap: add to mm/ |
1131 1132 |
tree->rbroot = RB_ROOT; spin_unlock(&tree->lock); |
aa9bca05a mm/zswap: bugfix:... |
1133 1134 |
kfree(tree); zswap_trees[type] = NULL; |
2b2811178 zswap: add to mm/ |
1135 |
} |
2b2811178 zswap: add to mm/ |
1136 1137 1138 1139 1140 |
static void zswap_frontswap_init(unsigned type) { struct zswap_tree *tree; tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL); |
60105e124 mm/zswap: support... |
1141 1142 1143 1144 1145 |
if (!tree) { pr_err("alloc failed, zswap disabled for swap type %d ", type); return; } |
2b2811178 zswap: add to mm/ |
1146 1147 1148 |
tree->rbroot = RB_ROOT; spin_lock_init(&tree->lock); zswap_trees[type] = tree; |
2b2811178 zswap: add to mm/ |
1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 |
} static struct frontswap_ops zswap_frontswap_ops = { .store = zswap_frontswap_store, .load = zswap_frontswap_load, .invalidate_page = zswap_frontswap_invalidate_page, .invalidate_area = zswap_frontswap_invalidate_area, .init = zswap_frontswap_init }; /********************************* * debugfs functions **********************************/ #ifdef CONFIG_DEBUG_FS #include <linux/debugfs.h> static struct dentry *zswap_debugfs_root; static int __init zswap_debugfs_init(void) { if (!debugfs_initialized()) return -ENODEV; zswap_debugfs_root = debugfs_create_dir("zswap", NULL); if (!zswap_debugfs_root) return -ENOMEM; debugfs_create_u64("pool_limit_hit", S_IRUGO, zswap_debugfs_root, &zswap_pool_limit_hit); debugfs_create_u64("reject_reclaim_fail", S_IRUGO, zswap_debugfs_root, &zswap_reject_reclaim_fail); debugfs_create_u64("reject_alloc_fail", S_IRUGO, zswap_debugfs_root, &zswap_reject_alloc_fail); debugfs_create_u64("reject_kmemcache_fail", S_IRUGO, zswap_debugfs_root, &zswap_reject_kmemcache_fail); debugfs_create_u64("reject_compress_poor", S_IRUGO, zswap_debugfs_root, &zswap_reject_compress_poor); debugfs_create_u64("written_back_pages", S_IRUGO, zswap_debugfs_root, &zswap_written_back_pages); debugfs_create_u64("duplicate_entry", S_IRUGO, zswap_debugfs_root, &zswap_duplicate_entry); |
12d79d64b mm/zpool: update ... |
1190 1191 |
debugfs_create_u64("pool_total_size", S_IRUGO, zswap_debugfs_root, &zswap_pool_total_size); |
2b2811178 zswap: add to mm/ |
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 |
debugfs_create_atomic_t("stored_pages", S_IRUGO, zswap_debugfs_root, &zswap_stored_pages); return 0; } static void __exit zswap_debugfs_exit(void) { debugfs_remove_recursive(zswap_debugfs_root); } #else static int __init zswap_debugfs_init(void) { return 0; } static void __exit zswap_debugfs_exit(void) { } #endif /********************************* * module init and exit **********************************/ static int __init init_zswap(void) { |
f1c54846e zswap: dynamic po... |
1216 |
struct zswap_pool *pool; |
60105e124 mm/zswap: support... |
1217 |
|
90b0fc26d zswap: change zpo... |
1218 |
zswap_init_started = true; |
2b2811178 zswap: add to mm/ |
1219 1220 1221 |
if (zswap_entry_cache_create()) { pr_err("entry cache creation failed "); |
f1c54846e zswap: dynamic po... |
1222 |
goto cache_fail; |
2b2811178 zswap: add to mm/ |
1223 |
} |
f1c54846e zswap: dynamic po... |
1224 1225 1226 1227 1228 |
if (zswap_cpu_dstmem_init()) { pr_err("dstmem alloc failed "); goto dstmem_fail; |
2b2811178 zswap: add to mm/ |
1229 |
} |
f1c54846e zswap: dynamic po... |
1230 1231 1232 1233 1234 1235 |
pool = __zswap_pool_create_fallback(); if (!pool) { pr_err("pool creation failed "); goto pool_fail; |
2b2811178 zswap: add to mm/ |
1236 |
} |
f1c54846e zswap: dynamic po... |
1237 1238 1239 1240 1241 |
pr_info("loaded using pool %s/%s ", pool->tfm_name, zpool_get_type(pool->zpool)); list_add(&pool->list, &zswap_pools); |
60105e124 mm/zswap: support... |
1242 |
|
2b2811178 zswap: add to mm/ |
1243 1244 1245 1246 1247 |
frontswap_register_ops(&zswap_frontswap_ops); if (zswap_debugfs_init()) pr_warn("debugfs initialization failed "); return 0; |
f1c54846e zswap: dynamic po... |
1248 1249 1250 1251 |
pool_fail: zswap_cpu_dstmem_destroy(); dstmem_fail: |
c119239b1 mm/zswap.c: add _... |
1252 |
zswap_entry_cache_destroy(); |
f1c54846e zswap: dynamic po... |
1253 |
cache_fail: |
2b2811178 zswap: add to mm/ |
1254 1255 1256 1257 1258 1259 |
return -ENOMEM; } /* must be late so crypto has time to come up */ late_initcall(init_zswap); MODULE_LICENSE("GPL"); |
68386da82 zbud, zswap: chan... |
1260 |
MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>"); |
2b2811178 zswap: add to mm/ |
1261 |
MODULE_DESCRIPTION("Compressed cache for swap pages"); |