blob: 0cfce9bc51e4946c561e48b8cb5f9e6cf7669d5f [file] [log] [blame]
Seth Jennings2b281112013-07-10 16:05:03 -07001/*
2 * zswap.c - zswap driver file
3 *
4 * zswap is a backend for frontswap that takes pages that are in the process
5 * of being swapped out and attempts to compress and store them in a
6 * RAM-based memory pool. This can result in a significant I/O reduction on
7 * the swap device and, in the case where decompressing from RAM is faster
8 * than reading from the swap device, can also improve workload performance.
9 *
10 * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
21*/
22
23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25#include <linux/module.h>
26#include <linux/cpu.h>
27#include <linux/highmem.h>
28#include <linux/slab.h>
29#include <linux/spinlock.h>
30#include <linux/types.h>
31#include <linux/atomic.h>
32#include <linux/frontswap.h>
33#include <linux/rbtree.h>
34#include <linux/swap.h>
35#include <linux/crypto.h>
36#include <linux/mempool.h>
Dan Streetman12d79d62014-08-06 16:08:40 -070037#include <linux/zpool.h>
Seth Jennings2b281112013-07-10 16:05:03 -070038
39#include <linux/mm_types.h>
40#include <linux/page-flags.h>
41#include <linux/swapops.h>
42#include <linux/writeback.h>
43#include <linux/pagemap.h>
44
45/*********************************
46* statistics
47**********************************/
Dan Streetman12d79d62014-08-06 16:08:40 -070048/* Total bytes used by the compressed storage */
49static u64 zswap_pool_total_size;
Seth Jennings2b281112013-07-10 16:05:03 -070050/* The number of compressed pages currently stored in zswap */
51static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
52
53/*
54 * The statistics below are not protected from concurrent access for
55 * performance reasons so they may not be a 100% accurate. However,
56 * they do provide useful information on roughly how many times a
57 * certain event is occurring.
58*/
59
60/* Pool limit was hit (see zswap_max_pool_percent) */
61static u64 zswap_pool_limit_hit;
62/* Pages written back when pool limit was reached */
63static u64 zswap_written_back_pages;
64/* Store failed due to a reclaim failure after pool limit was reached */
65static u64 zswap_reject_reclaim_fail;
66/* Compressed page was too big for the allocator to (optimally) store */
67static u64 zswap_reject_compress_poor;
68/* Store failed because underlying allocator could not get memory */
69static u64 zswap_reject_alloc_fail;
70/* Store failed because the entry metadata could not be allocated (rare) */
71static u64 zswap_reject_kmemcache_fail;
72/* Duplicate store was encountered (rare) */
73static u64 zswap_duplicate_entry;
74
75/*********************************
76* tunables
77**********************************/
78/* Enable/disable zswap (disabled by default, fixed at boot for now) */
79static bool zswap_enabled __read_mostly;
Dan Streetman12ab0282014-01-23 15:52:48 -080080module_param_named(enabled, zswap_enabled, bool, 0444);
Seth Jennings2b281112013-07-10 16:05:03 -070081
82/* Compressor to be used by zswap (fixed at boot for now) */
83#define ZSWAP_COMPRESSOR_DEFAULT "lzo"
84static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
Dan Streetman12ab0282014-01-23 15:52:48 -080085module_param_named(compressor, zswap_compressor, charp, 0444);
Seth Jennings2b281112013-07-10 16:05:03 -070086
87/* The maximum percentage of memory that the compressed pool can occupy */
88static unsigned int zswap_max_pool_percent = 20;
89module_param_named(max_pool_percent,
90 zswap_max_pool_percent, uint, 0644);
91
Dan Streetman12d79d62014-08-06 16:08:40 -070092/* Compressed storage to use */
93#define ZSWAP_ZPOOL_DEFAULT "zbud"
94static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
95module_param_named(zpool, zswap_zpool_type, charp, 0444);
96
97/* zpool is shared by all of zswap backend */
98static struct zpool *zswap_pool;
Minchan Kim60105e12014-04-07 15:38:27 -070099
Seth Jennings2b281112013-07-10 16:05:03 -0700100/*********************************
101* compression functions
102**********************************/
103/* per-cpu compression transforms */
104static struct crypto_comp * __percpu *zswap_comp_pcpu_tfms;
105
106enum comp_op {
107 ZSWAP_COMPOP_COMPRESS,
108 ZSWAP_COMPOP_DECOMPRESS
109};
110
111static int zswap_comp_op(enum comp_op op, const u8 *src, unsigned int slen,
112 u8 *dst, unsigned int *dlen)
113{
114 struct crypto_comp *tfm;
115 int ret;
116
117 tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, get_cpu());
118 switch (op) {
119 case ZSWAP_COMPOP_COMPRESS:
120 ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
121 break;
122 case ZSWAP_COMPOP_DECOMPRESS:
123 ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
124 break;
125 default:
126 ret = -EINVAL;
127 }
128
129 put_cpu();
130 return ret;
131}
132
133static int __init zswap_comp_init(void)
134{
135 if (!crypto_has_comp(zswap_compressor, 0, 0)) {
136 pr_info("%s compressor not available\n", zswap_compressor);
137 /* fall back to default compressor */
138 zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
139 if (!crypto_has_comp(zswap_compressor, 0, 0))
140 /* can't even load the default compressor */
141 return -ENODEV;
142 }
143 pr_info("using %s compressor\n", zswap_compressor);
144
145 /* alloc percpu transforms */
146 zswap_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *);
147 if (!zswap_comp_pcpu_tfms)
148 return -ENOMEM;
149 return 0;
150}
151
Mahendran Ganeshdd01d7d2014-12-12 16:57:15 -0800152static void __init zswap_comp_exit(void)
Seth Jennings2b281112013-07-10 16:05:03 -0700153{
154 /* free percpu transforms */
Markus Elfring442cc432014-12-12 16:57:18 -0800155 free_percpu(zswap_comp_pcpu_tfms);
Seth Jennings2b281112013-07-10 16:05:03 -0700156}
157
158/*********************************
159* data structures
160**********************************/
161/*
162 * struct zswap_entry
163 *
164 * This structure contains the metadata for tracking a single compressed
165 * page within zswap.
166 *
167 * rbnode - links the entry into red-black tree for the appropriate swap type
168 * refcount - the number of outstanding reference to the entry. This is needed
169 * to protect against premature freeing of the entry by code
SeongJae Park6b452512014-04-07 15:38:25 -0700170 * concurrent calls to load, invalidate, and writeback. The lock
Seth Jennings2b281112013-07-10 16:05:03 -0700171 * for the zswap_tree structure that contains the entry must
172 * be held while changing the refcount. Since the lock must
173 * be held, there is no reason to also make refcount atomic.
174 * offset - the swap offset for the entry. Index into the red-black tree.
Dan Streetman12d79d62014-08-06 16:08:40 -0700175 * handle - zpool allocation handle that stores the compressed page data
Seth Jennings2b281112013-07-10 16:05:03 -0700176 * length - the length in bytes of the compressed page data. Needed during
SeongJae Park6b452512014-04-07 15:38:25 -0700177 * decompression
Seth Jennings2b281112013-07-10 16:05:03 -0700178 */
179struct zswap_entry {
180 struct rb_node rbnode;
181 pgoff_t offset;
182 int refcount;
183 unsigned int length;
184 unsigned long handle;
185};
186
187struct zswap_header {
188 swp_entry_t swpentry;
189};
190
191/*
192 * The tree lock in the zswap_tree struct protects a few things:
193 * - the rbtree
194 * - the refcount field of each entry in the tree
195 */
196struct zswap_tree {
197 struct rb_root rbroot;
198 spinlock_t lock;
Seth Jennings2b281112013-07-10 16:05:03 -0700199};
200
201static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
202
203/*********************************
204* zswap entry functions
205**********************************/
206static struct kmem_cache *zswap_entry_cache;
207
Mahendran Ganeshdd01d7d2014-12-12 16:57:15 -0800208static int __init zswap_entry_cache_create(void)
Seth Jennings2b281112013-07-10 16:05:03 -0700209{
210 zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
SeongJae Park5d2d42d2014-04-07 15:38:28 -0700211 return zswap_entry_cache == NULL;
Seth Jennings2b281112013-07-10 16:05:03 -0700212}
213
Fabian Frederickc1192392014-08-08 14:19:35 -0700214static void __init zswap_entry_cache_destroy(void)
Seth Jennings2b281112013-07-10 16:05:03 -0700215{
216 kmem_cache_destroy(zswap_entry_cache);
217}
218
219static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
220{
221 struct zswap_entry *entry;
222 entry = kmem_cache_alloc(zswap_entry_cache, gfp);
223 if (!entry)
224 return NULL;
225 entry->refcount = 1;
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800226 RB_CLEAR_NODE(&entry->rbnode);
Seth Jennings2b281112013-07-10 16:05:03 -0700227 return entry;
228}
229
230static void zswap_entry_cache_free(struct zswap_entry *entry)
231{
232 kmem_cache_free(zswap_entry_cache, entry);
233}
234
Seth Jennings2b281112013-07-10 16:05:03 -0700235/*********************************
236* rbtree functions
237**********************************/
238static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
239{
240 struct rb_node *node = root->rb_node;
241 struct zswap_entry *entry;
242
243 while (node) {
244 entry = rb_entry(node, struct zswap_entry, rbnode);
245 if (entry->offset > offset)
246 node = node->rb_left;
247 else if (entry->offset < offset)
248 node = node->rb_right;
249 else
250 return entry;
251 }
252 return NULL;
253}
254
255/*
256 * In the case that a entry with the same offset is found, a pointer to
257 * the existing entry is stored in dupentry and the function returns -EEXIST
258 */
259static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
260 struct zswap_entry **dupentry)
261{
262 struct rb_node **link = &root->rb_node, *parent = NULL;
263 struct zswap_entry *myentry;
264
265 while (*link) {
266 parent = *link;
267 myentry = rb_entry(parent, struct zswap_entry, rbnode);
268 if (myentry->offset > entry->offset)
269 link = &(*link)->rb_left;
270 else if (myentry->offset < entry->offset)
271 link = &(*link)->rb_right;
272 else {
273 *dupentry = myentry;
274 return -EEXIST;
275 }
276 }
277 rb_link_node(&entry->rbnode, parent, link);
278 rb_insert_color(&entry->rbnode, root);
279 return 0;
280}
281
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800282static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
283{
284 if (!RB_EMPTY_NODE(&entry->rbnode)) {
285 rb_erase(&entry->rbnode, root);
286 RB_CLEAR_NODE(&entry->rbnode);
287 }
288}
289
290/*
Dan Streetman12d79d62014-08-06 16:08:40 -0700291 * Carries out the common pattern of freeing and entry's zpool allocation,
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800292 * freeing the entry itself, and decrementing the number of stored pages.
293 */
Minchan Kim60105e12014-04-07 15:38:27 -0700294static void zswap_free_entry(struct zswap_entry *entry)
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800295{
Dan Streetman12d79d62014-08-06 16:08:40 -0700296 zpool_free(zswap_pool, entry->handle);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800297 zswap_entry_cache_free(entry);
298 atomic_dec(&zswap_stored_pages);
Dan Streetman12d79d62014-08-06 16:08:40 -0700299 zswap_pool_total_size = zpool_get_total_size(zswap_pool);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800300}
301
302/* caller must hold the tree lock */
303static void zswap_entry_get(struct zswap_entry *entry)
304{
305 entry->refcount++;
306}
307
308/* caller must hold the tree lock
309* remove from the tree and free it, if nobody reference the entry
310*/
311static void zswap_entry_put(struct zswap_tree *tree,
312 struct zswap_entry *entry)
313{
314 int refcount = --entry->refcount;
315
316 BUG_ON(refcount < 0);
317 if (refcount == 0) {
318 zswap_rb_erase(&tree->rbroot, entry);
Minchan Kim60105e12014-04-07 15:38:27 -0700319 zswap_free_entry(entry);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800320 }
321}
322
323/* caller must hold the tree lock */
324static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
325 pgoff_t offset)
326{
327 struct zswap_entry *entry = NULL;
328
329 entry = zswap_rb_search(root, offset);
330 if (entry)
331 zswap_entry_get(entry);
332
333 return entry;
334}
335
Seth Jennings2b281112013-07-10 16:05:03 -0700336/*********************************
337* per-cpu code
338**********************************/
339static DEFINE_PER_CPU(u8 *, zswap_dstmem);
340
341static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu)
342{
343 struct crypto_comp *tfm;
344 u8 *dst;
345
346 switch (action) {
347 case CPU_UP_PREPARE:
348 tfm = crypto_alloc_comp(zswap_compressor, 0, 0);
349 if (IS_ERR(tfm)) {
350 pr_err("can't allocate compressor transform\n");
351 return NOTIFY_BAD;
352 }
353 *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = tfm;
Eric Dumazet72d09632014-06-04 16:11:11 -0700354 dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
Seth Jennings2b281112013-07-10 16:05:03 -0700355 if (!dst) {
356 pr_err("can't allocate compressor buffer\n");
357 crypto_free_comp(tfm);
358 *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
359 return NOTIFY_BAD;
360 }
361 per_cpu(zswap_dstmem, cpu) = dst;
362 break;
363 case CPU_DEAD:
364 case CPU_UP_CANCELED:
365 tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu);
366 if (tfm) {
367 crypto_free_comp(tfm);
368 *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
369 }
370 dst = per_cpu(zswap_dstmem, cpu);
371 kfree(dst);
372 per_cpu(zswap_dstmem, cpu) = NULL;
373 break;
374 default:
375 break;
376 }
377 return NOTIFY_OK;
378}
379
380static int zswap_cpu_notifier(struct notifier_block *nb,
381 unsigned long action, void *pcpu)
382{
383 unsigned long cpu = (unsigned long)pcpu;
384 return __zswap_cpu_notifier(action, cpu);
385}
386
387static struct notifier_block zswap_cpu_notifier_block = {
388 .notifier_call = zswap_cpu_notifier
389};
390
Mahendran Ganeshdd01d7d2014-12-12 16:57:15 -0800391static int __init zswap_cpu_init(void)
Seth Jennings2b281112013-07-10 16:05:03 -0700392{
393 unsigned long cpu;
394
Srivatsa S. Bhat57637822014-03-11 02:12:40 +0530395 cpu_notifier_register_begin();
Seth Jennings2b281112013-07-10 16:05:03 -0700396 for_each_online_cpu(cpu)
397 if (__zswap_cpu_notifier(CPU_UP_PREPARE, cpu) != NOTIFY_OK)
398 goto cleanup;
Srivatsa S. Bhat57637822014-03-11 02:12:40 +0530399 __register_cpu_notifier(&zswap_cpu_notifier_block);
400 cpu_notifier_register_done();
Seth Jennings2b281112013-07-10 16:05:03 -0700401 return 0;
402
403cleanup:
404 for_each_online_cpu(cpu)
405 __zswap_cpu_notifier(CPU_UP_CANCELED, cpu);
Srivatsa S. Bhat57637822014-03-11 02:12:40 +0530406 cpu_notifier_register_done();
Seth Jennings2b281112013-07-10 16:05:03 -0700407 return -ENOMEM;
408}
409
410/*********************************
411* helpers
412**********************************/
413static bool zswap_is_full(void)
414{
SeongJae Park5d2d42d2014-04-07 15:38:28 -0700415 return totalram_pages * zswap_max_pool_percent / 100 <
Dan Streetman12d79d62014-08-06 16:08:40 -0700416 DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
Seth Jennings2b281112013-07-10 16:05:03 -0700417}
418
Seth Jennings2b281112013-07-10 16:05:03 -0700419/*********************************
420* writeback code
421**********************************/
422/* return enum for zswap_get_swap_cache_page */
423enum zswap_get_swap_ret {
424 ZSWAP_SWAPCACHE_NEW,
425 ZSWAP_SWAPCACHE_EXIST,
Weijie Yang67d13fe2013-11-12 15:08:26 -0800426 ZSWAP_SWAPCACHE_FAIL,
Seth Jennings2b281112013-07-10 16:05:03 -0700427};
428
429/*
430 * zswap_get_swap_cache_page
431 *
432 * This is an adaption of read_swap_cache_async()
433 *
434 * This function tries to find a page with the given swap entry
435 * in the swapper_space address space (the swap cache). If the page
436 * is found, it is returned in retpage. Otherwise, a page is allocated,
437 * added to the swap cache, and returned in retpage.
438 *
439 * If success, the swap cache page is returned in retpage
Weijie Yang67d13fe2013-11-12 15:08:26 -0800440 * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
441 * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
442 * the new page is added to swapcache and locked
443 * Returns ZSWAP_SWAPCACHE_FAIL on error
Seth Jennings2b281112013-07-10 16:05:03 -0700444 */
445static int zswap_get_swap_cache_page(swp_entry_t entry,
446 struct page **retpage)
447{
448 struct page *found_page, *new_page = NULL;
Sunghan Suh822518d2013-09-11 14:20:22 -0700449 struct address_space *swapper_space = swap_address_space(entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700450 int err;
451
452 *retpage = NULL;
453 do {
454 /*
455 * First check the swap cache. Since this is normally
456 * called after lookup_swap_cache() failed, re-calling
457 * that would confuse statistics.
458 */
459 found_page = find_get_page(swapper_space, entry.val);
460 if (found_page)
461 break;
462
463 /*
464 * Get a new page to read into from swap.
465 */
466 if (!new_page) {
467 new_page = alloc_page(GFP_KERNEL);
468 if (!new_page)
469 break; /* Out of memory */
470 }
471
472 /*
473 * call radix_tree_preload() while we can wait.
474 */
475 err = radix_tree_preload(GFP_KERNEL);
476 if (err)
477 break;
478
479 /*
480 * Swap entry may have been freed since our caller observed it.
481 */
482 err = swapcache_prepare(entry);
483 if (err == -EEXIST) { /* seems racy */
484 radix_tree_preload_end();
485 continue;
486 }
487 if (err) { /* swp entry is obsolete ? */
488 radix_tree_preload_end();
489 break;
490 }
491
492 /* May fail (-ENOMEM) if radix-tree node allocation failed. */
493 __set_page_locked(new_page);
494 SetPageSwapBacked(new_page);
495 err = __add_to_swap_cache(new_page, entry);
496 if (likely(!err)) {
497 radix_tree_preload_end();
498 lru_cache_add_anon(new_page);
499 *retpage = new_page;
500 return ZSWAP_SWAPCACHE_NEW;
501 }
502 radix_tree_preload_end();
503 ClearPageSwapBacked(new_page);
504 __clear_page_locked(new_page);
505 /*
506 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
507 * clear SWAP_HAS_CACHE flag.
508 */
Johannes Weiner0a31bc92014-08-08 14:19:22 -0700509 swapcache_free(entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700510 } while (err != -ENOMEM);
511
512 if (new_page)
513 page_cache_release(new_page);
514 if (!found_page)
Weijie Yang67d13fe2013-11-12 15:08:26 -0800515 return ZSWAP_SWAPCACHE_FAIL;
Seth Jennings2b281112013-07-10 16:05:03 -0700516 *retpage = found_page;
517 return ZSWAP_SWAPCACHE_EXIST;
518}
519
520/*
521 * Attempts to free an entry by adding a page to the swap cache,
522 * decompressing the entry data into the page, and issuing a
523 * bio write to write the page back to the swap device.
524 *
525 * This can be thought of as a "resumed writeback" of the page
526 * to the swap device. We are basically resuming the same swap
527 * writeback path that was intercepted with the frontswap_store()
528 * in the first place. After the page has been decompressed into
529 * the swap cache, the compressed version stored by zswap can be
530 * freed.
531 */
Dan Streetman12d79d62014-08-06 16:08:40 -0700532static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
Seth Jennings2b281112013-07-10 16:05:03 -0700533{
534 struct zswap_header *zhdr;
535 swp_entry_t swpentry;
536 struct zswap_tree *tree;
537 pgoff_t offset;
538 struct zswap_entry *entry;
539 struct page *page;
540 u8 *src, *dst;
541 unsigned int dlen;
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800542 int ret;
Seth Jennings2b281112013-07-10 16:05:03 -0700543 struct writeback_control wbc = {
544 .sync_mode = WB_SYNC_NONE,
545 };
546
547 /* extract swpentry from data */
Dan Streetman12d79d62014-08-06 16:08:40 -0700548 zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
Seth Jennings2b281112013-07-10 16:05:03 -0700549 swpentry = zhdr->swpentry; /* here */
Dan Streetman12d79d62014-08-06 16:08:40 -0700550 zpool_unmap_handle(pool, handle);
Seth Jennings2b281112013-07-10 16:05:03 -0700551 tree = zswap_trees[swp_type(swpentry)];
552 offset = swp_offset(swpentry);
Seth Jennings2b281112013-07-10 16:05:03 -0700553
554 /* find and ref zswap entry */
555 spin_lock(&tree->lock);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800556 entry = zswap_entry_find_get(&tree->rbroot, offset);
Seth Jennings2b281112013-07-10 16:05:03 -0700557 if (!entry) {
558 /* entry was invalidated */
559 spin_unlock(&tree->lock);
560 return 0;
561 }
Seth Jennings2b281112013-07-10 16:05:03 -0700562 spin_unlock(&tree->lock);
563 BUG_ON(offset != entry->offset);
564
565 /* try to allocate swap cache page */
566 switch (zswap_get_swap_cache_page(swpentry, &page)) {
Weijie Yang67d13fe2013-11-12 15:08:26 -0800567 case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
Seth Jennings2b281112013-07-10 16:05:03 -0700568 ret = -ENOMEM;
569 goto fail;
570
Weijie Yang67d13fe2013-11-12 15:08:26 -0800571 case ZSWAP_SWAPCACHE_EXIST:
Seth Jennings2b281112013-07-10 16:05:03 -0700572 /* page is already in the swap cache, ignore for now */
573 page_cache_release(page);
574 ret = -EEXIST;
575 goto fail;
576
577 case ZSWAP_SWAPCACHE_NEW: /* page is locked */
578 /* decompress */
579 dlen = PAGE_SIZE;
Dan Streetman12d79d62014-08-06 16:08:40 -0700580 src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
581 ZPOOL_MM_RO) + sizeof(struct zswap_header);
Seth Jennings2b281112013-07-10 16:05:03 -0700582 dst = kmap_atomic(page);
583 ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src,
584 entry->length, dst, &dlen);
585 kunmap_atomic(dst);
Dan Streetman12d79d62014-08-06 16:08:40 -0700586 zpool_unmap_handle(zswap_pool, entry->handle);
Seth Jennings2b281112013-07-10 16:05:03 -0700587 BUG_ON(ret);
588 BUG_ON(dlen != PAGE_SIZE);
589
590 /* page is up to date */
591 SetPageUptodate(page);
592 }
593
Weijie Yangb349acc2013-11-12 15:07:52 -0800594 /* move it to the tail of the inactive list after end_writeback */
595 SetPageReclaim(page);
596
Seth Jennings2b281112013-07-10 16:05:03 -0700597 /* start writeback */
598 __swap_writepage(page, &wbc, end_swap_bio_write);
599 page_cache_release(page);
600 zswap_written_back_pages++;
601
602 spin_lock(&tree->lock);
Seth Jennings2b281112013-07-10 16:05:03 -0700603 /* drop local reference */
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800604 zswap_entry_put(tree, entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700605
606 /*
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800607 * There are two possible situations for entry here:
608 * (1) refcount is 1(normal case), entry is valid and on the tree
609 * (2) refcount is 0, entry is freed and not on the tree
610 * because invalidate happened during writeback
611 * search the tree and free the entry if find entry
612 */
613 if (entry == zswap_rb_search(&tree->rbroot, offset))
614 zswap_entry_put(tree, entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700615 spin_unlock(&tree->lock);
Seth Jennings2b281112013-07-10 16:05:03 -0700616
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800617 goto end;
618
619 /*
620 * if we get here due to ZSWAP_SWAPCACHE_EXIST
621 * a load may happening concurrently
622 * it is safe and okay to not free the entry
623 * if we free the entry in the following put
624 * it it either okay to return !0
625 */
Seth Jennings2b281112013-07-10 16:05:03 -0700626fail:
627 spin_lock(&tree->lock);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800628 zswap_entry_put(tree, entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700629 spin_unlock(&tree->lock);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800630
631end:
Seth Jennings2b281112013-07-10 16:05:03 -0700632 return ret;
633}
634
635/*********************************
636* frontswap hooks
637**********************************/
638/* attempts to compress and store an single page */
639static int zswap_frontswap_store(unsigned type, pgoff_t offset,
640 struct page *page)
641{
642 struct zswap_tree *tree = zswap_trees[type];
643 struct zswap_entry *entry, *dupentry;
644 int ret;
645 unsigned int dlen = PAGE_SIZE, len;
646 unsigned long handle;
647 char *buf;
648 u8 *src, *dst;
649 struct zswap_header *zhdr;
650
651 if (!tree) {
652 ret = -ENODEV;
653 goto reject;
654 }
655
656 /* reclaim space if needed */
657 if (zswap_is_full()) {
658 zswap_pool_limit_hit++;
Dan Streetman12d79d62014-08-06 16:08:40 -0700659 if (zpool_shrink(zswap_pool, 1, NULL)) {
Seth Jennings2b281112013-07-10 16:05:03 -0700660 zswap_reject_reclaim_fail++;
661 ret = -ENOMEM;
662 goto reject;
663 }
664 }
665
666 /* allocate entry */
667 entry = zswap_entry_cache_alloc(GFP_KERNEL);
668 if (!entry) {
669 zswap_reject_kmemcache_fail++;
670 ret = -ENOMEM;
671 goto reject;
672 }
673
674 /* compress */
675 dst = get_cpu_var(zswap_dstmem);
676 src = kmap_atomic(page);
677 ret = zswap_comp_op(ZSWAP_COMPOP_COMPRESS, src, PAGE_SIZE, dst, &dlen);
678 kunmap_atomic(src);
679 if (ret) {
680 ret = -EINVAL;
681 goto freepage;
682 }
683
684 /* store */
685 len = dlen + sizeof(struct zswap_header);
Dan Streetman12d79d62014-08-06 16:08:40 -0700686 ret = zpool_malloc(zswap_pool, len, __GFP_NORETRY | __GFP_NOWARN,
Seth Jennings2b281112013-07-10 16:05:03 -0700687 &handle);
688 if (ret == -ENOSPC) {
689 zswap_reject_compress_poor++;
690 goto freepage;
691 }
692 if (ret) {
693 zswap_reject_alloc_fail++;
694 goto freepage;
695 }
Dan Streetman12d79d62014-08-06 16:08:40 -0700696 zhdr = zpool_map_handle(zswap_pool, handle, ZPOOL_MM_RW);
Seth Jennings2b281112013-07-10 16:05:03 -0700697 zhdr->swpentry = swp_entry(type, offset);
698 buf = (u8 *)(zhdr + 1);
699 memcpy(buf, dst, dlen);
Dan Streetman12d79d62014-08-06 16:08:40 -0700700 zpool_unmap_handle(zswap_pool, handle);
Seth Jennings2b281112013-07-10 16:05:03 -0700701 put_cpu_var(zswap_dstmem);
702
703 /* populate entry */
704 entry->offset = offset;
705 entry->handle = handle;
706 entry->length = dlen;
707
708 /* map */
709 spin_lock(&tree->lock);
710 do {
711 ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
712 if (ret == -EEXIST) {
713 zswap_duplicate_entry++;
714 /* remove from rbtree */
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800715 zswap_rb_erase(&tree->rbroot, dupentry);
716 zswap_entry_put(tree, dupentry);
Seth Jennings2b281112013-07-10 16:05:03 -0700717 }
718 } while (ret == -EEXIST);
719 spin_unlock(&tree->lock);
720
721 /* update stats */
722 atomic_inc(&zswap_stored_pages);
Dan Streetman12d79d62014-08-06 16:08:40 -0700723 zswap_pool_total_size = zpool_get_total_size(zswap_pool);
Seth Jennings2b281112013-07-10 16:05:03 -0700724
725 return 0;
726
727freepage:
728 put_cpu_var(zswap_dstmem);
729 zswap_entry_cache_free(entry);
730reject:
731 return ret;
732}
733
734/*
735 * returns 0 if the page was successfully decompressed
736 * return -1 on entry not found or error
737*/
738static int zswap_frontswap_load(unsigned type, pgoff_t offset,
739 struct page *page)
740{
741 struct zswap_tree *tree = zswap_trees[type];
742 struct zswap_entry *entry;
743 u8 *src, *dst;
744 unsigned int dlen;
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800745 int ret;
Seth Jennings2b281112013-07-10 16:05:03 -0700746
747 /* find */
748 spin_lock(&tree->lock);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800749 entry = zswap_entry_find_get(&tree->rbroot, offset);
Seth Jennings2b281112013-07-10 16:05:03 -0700750 if (!entry) {
751 /* entry was written back */
752 spin_unlock(&tree->lock);
753 return -1;
754 }
Seth Jennings2b281112013-07-10 16:05:03 -0700755 spin_unlock(&tree->lock);
756
757 /* decompress */
758 dlen = PAGE_SIZE;
Dan Streetman12d79d62014-08-06 16:08:40 -0700759 src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
760 ZPOOL_MM_RO) + sizeof(struct zswap_header);
Seth Jennings2b281112013-07-10 16:05:03 -0700761 dst = kmap_atomic(page);
762 ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length,
763 dst, &dlen);
764 kunmap_atomic(dst);
Dan Streetman12d79d62014-08-06 16:08:40 -0700765 zpool_unmap_handle(zswap_pool, entry->handle);
Seth Jennings2b281112013-07-10 16:05:03 -0700766 BUG_ON(ret);
767
768 spin_lock(&tree->lock);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800769 zswap_entry_put(tree, entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700770 spin_unlock(&tree->lock);
771
Seth Jennings2b281112013-07-10 16:05:03 -0700772 return 0;
773}
774
775/* frees an entry in zswap */
776static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
777{
778 struct zswap_tree *tree = zswap_trees[type];
779 struct zswap_entry *entry;
Seth Jennings2b281112013-07-10 16:05:03 -0700780
781 /* find */
782 spin_lock(&tree->lock);
783 entry = zswap_rb_search(&tree->rbroot, offset);
784 if (!entry) {
785 /* entry was written back */
786 spin_unlock(&tree->lock);
787 return;
788 }
789
790 /* remove from rbtree */
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800791 zswap_rb_erase(&tree->rbroot, entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700792
793 /* drop the initial reference from entry creation */
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800794 zswap_entry_put(tree, entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700795
796 spin_unlock(&tree->lock);
Seth Jennings2b281112013-07-10 16:05:03 -0700797}
798
799/* frees all zswap entries for the given swap type */
800static void zswap_frontswap_invalidate_area(unsigned type)
801{
802 struct zswap_tree *tree = zswap_trees[type];
Cody P Schafer0bd42132013-09-11 14:25:33 -0700803 struct zswap_entry *entry, *n;
Seth Jennings2b281112013-07-10 16:05:03 -0700804
805 if (!tree)
806 return;
807
808 /* walk the tree and free everything */
809 spin_lock(&tree->lock);
Weijie Yang0ab0abc2013-11-12 15:08:27 -0800810 rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
Minchan Kim60105e12014-04-07 15:38:27 -0700811 zswap_free_entry(entry);
Seth Jennings2b281112013-07-10 16:05:03 -0700812 tree->rbroot = RB_ROOT;
813 spin_unlock(&tree->lock);
Weijie Yangaa9bca02013-10-16 13:46:54 -0700814 kfree(tree);
815 zswap_trees[type] = NULL;
Seth Jennings2b281112013-07-10 16:05:03 -0700816}
817
Dan Streetman12d79d62014-08-06 16:08:40 -0700818static struct zpool_ops zswap_zpool_ops = {
Seth Jennings2b281112013-07-10 16:05:03 -0700819 .evict = zswap_writeback_entry
820};
821
822static void zswap_frontswap_init(unsigned type)
823{
824 struct zswap_tree *tree;
825
826 tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL);
Minchan Kim60105e12014-04-07 15:38:27 -0700827 if (!tree) {
828 pr_err("alloc failed, zswap disabled for swap type %d\n", type);
829 return;
830 }
831
Seth Jennings2b281112013-07-10 16:05:03 -0700832 tree->rbroot = RB_ROOT;
833 spin_lock_init(&tree->lock);
834 zswap_trees[type] = tree;
Seth Jennings2b281112013-07-10 16:05:03 -0700835}
836
837static struct frontswap_ops zswap_frontswap_ops = {
838 .store = zswap_frontswap_store,
839 .load = zswap_frontswap_load,
840 .invalidate_page = zswap_frontswap_invalidate_page,
841 .invalidate_area = zswap_frontswap_invalidate_area,
842 .init = zswap_frontswap_init
843};
844
845/*********************************
846* debugfs functions
847**********************************/
848#ifdef CONFIG_DEBUG_FS
849#include <linux/debugfs.h>
850
851static struct dentry *zswap_debugfs_root;
852
853static int __init zswap_debugfs_init(void)
854{
855 if (!debugfs_initialized())
856 return -ENODEV;
857
858 zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
859 if (!zswap_debugfs_root)
860 return -ENOMEM;
861
862 debugfs_create_u64("pool_limit_hit", S_IRUGO,
863 zswap_debugfs_root, &zswap_pool_limit_hit);
864 debugfs_create_u64("reject_reclaim_fail", S_IRUGO,
865 zswap_debugfs_root, &zswap_reject_reclaim_fail);
866 debugfs_create_u64("reject_alloc_fail", S_IRUGO,
867 zswap_debugfs_root, &zswap_reject_alloc_fail);
868 debugfs_create_u64("reject_kmemcache_fail", S_IRUGO,
869 zswap_debugfs_root, &zswap_reject_kmemcache_fail);
870 debugfs_create_u64("reject_compress_poor", S_IRUGO,
871 zswap_debugfs_root, &zswap_reject_compress_poor);
872 debugfs_create_u64("written_back_pages", S_IRUGO,
873 zswap_debugfs_root, &zswap_written_back_pages);
874 debugfs_create_u64("duplicate_entry", S_IRUGO,
875 zswap_debugfs_root, &zswap_duplicate_entry);
Dan Streetman12d79d62014-08-06 16:08:40 -0700876 debugfs_create_u64("pool_total_size", S_IRUGO,
877 zswap_debugfs_root, &zswap_pool_total_size);
Seth Jennings2b281112013-07-10 16:05:03 -0700878 debugfs_create_atomic_t("stored_pages", S_IRUGO,
879 zswap_debugfs_root, &zswap_stored_pages);
880
881 return 0;
882}
883
884static void __exit zswap_debugfs_exit(void)
885{
886 debugfs_remove_recursive(zswap_debugfs_root);
887}
888#else
889static int __init zswap_debugfs_init(void)
890{
891 return 0;
892}
893
894static void __exit zswap_debugfs_exit(void) { }
895#endif
896
897/*********************************
898* module init and exit
899**********************************/
900static int __init init_zswap(void)
901{
Dan Streetman12d79d62014-08-06 16:08:40 -0700902 gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
903
Seth Jennings2b281112013-07-10 16:05:03 -0700904 if (!zswap_enabled)
905 return 0;
906
907 pr_info("loading zswap\n");
Minchan Kim60105e12014-04-07 15:38:27 -0700908
Dan Streetman12d79d62014-08-06 16:08:40 -0700909 zswap_pool = zpool_create_pool(zswap_zpool_type, gfp, &zswap_zpool_ops);
910 if (!zswap_pool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
911 pr_info("%s zpool not available\n", zswap_zpool_type);
912 zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
913 zswap_pool = zpool_create_pool(zswap_zpool_type, gfp,
914 &zswap_zpool_ops);
915 }
Minchan Kim60105e12014-04-07 15:38:27 -0700916 if (!zswap_pool) {
Dan Streetman12d79d62014-08-06 16:08:40 -0700917 pr_err("%s zpool not available\n", zswap_zpool_type);
918 pr_err("zpool creation failed\n");
Minchan Kim60105e12014-04-07 15:38:27 -0700919 goto error;
920 }
Dan Streetman12d79d62014-08-06 16:08:40 -0700921 pr_info("using %s pool\n", zswap_zpool_type);
Minchan Kim60105e12014-04-07 15:38:27 -0700922
Seth Jennings2b281112013-07-10 16:05:03 -0700923 if (zswap_entry_cache_create()) {
924 pr_err("entry cache creation failed\n");
Minchan Kim60105e12014-04-07 15:38:27 -0700925 goto cachefail;
Seth Jennings2b281112013-07-10 16:05:03 -0700926 }
927 if (zswap_comp_init()) {
928 pr_err("compressor initialization failed\n");
929 goto compfail;
930 }
931 if (zswap_cpu_init()) {
932 pr_err("per-cpu initialization failed\n");
933 goto pcpufail;
934 }
Minchan Kim60105e12014-04-07 15:38:27 -0700935
Seth Jennings2b281112013-07-10 16:05:03 -0700936 frontswap_register_ops(&zswap_frontswap_ops);
937 if (zswap_debugfs_init())
938 pr_warn("debugfs initialization failed\n");
939 return 0;
940pcpufail:
941 zswap_comp_exit();
942compfail:
Fabian Frederickc1192392014-08-08 14:19:35 -0700943 zswap_entry_cache_destroy();
Minchan Kim60105e12014-04-07 15:38:27 -0700944cachefail:
Dan Streetman12d79d62014-08-06 16:08:40 -0700945 zpool_destroy_pool(zswap_pool);
Seth Jennings2b281112013-07-10 16:05:03 -0700946error:
947 return -ENOMEM;
948}
949/* must be late so crypto has time to come up */
950late_initcall(init_zswap);
951
952MODULE_LICENSE("GPL");
Seth Jennings68386da2014-11-12 21:08:46 -0600953MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
Seth Jennings2b281112013-07-10 16:05:03 -0700954MODULE_DESCRIPTION("Compressed cache for swap pages");