2 * zswap.c - zswap driver file
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.
10 * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
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.
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.
23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
37 #include <linux/zpool.h>
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>
45 /*********************************
47 **********************************/
48 /* Total bytes used by the compressed storage */
49 static u64 zswap_pool_total_size
;
50 /* The number of compressed pages currently stored in zswap */
51 static atomic_t zswap_stored_pages
= ATOMIC_INIT(0);
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.
60 /* Pool limit was hit (see zswap_max_pool_percent) */
61 static u64 zswap_pool_limit_hit
;
62 /* Pages written back when pool limit was reached */
63 static u64 zswap_written_back_pages
;
64 /* Store failed due to a reclaim failure after pool limit was reached */
65 static u64 zswap_reject_reclaim_fail
;
66 /* Compressed page was too big for the allocator to (optimally) store */
67 static u64 zswap_reject_compress_poor
;
68 /* Store failed because underlying allocator could not get memory */
69 static u64 zswap_reject_alloc_fail
;
70 /* Store failed because the entry metadata could not be allocated (rare) */
71 static u64 zswap_reject_kmemcache_fail
;
72 /* Duplicate store was encountered (rare) */
73 static u64 zswap_duplicate_entry
;
75 /*********************************
77 **********************************/
79 /* Enable/disable zswap (disabled by default) */
80 static bool zswap_enabled
;
81 module_param_named(enabled
, zswap_enabled
, bool, 0644);
83 /* Compressor to be used by zswap (fixed at boot for now) */
84 #define ZSWAP_COMPRESSOR_DEFAULT "lzo"
85 static char *zswap_compressor
= ZSWAP_COMPRESSOR_DEFAULT
;
86 module_param_named(compressor
, zswap_compressor
, charp
, 0444);
88 /* The maximum percentage of memory that the compressed pool can occupy */
89 static unsigned int zswap_max_pool_percent
= 20;
90 module_param_named(max_pool_percent
,
91 zswap_max_pool_percent
, uint
, 0644);
93 /* Compressed storage to use */
94 #define ZSWAP_ZPOOL_DEFAULT "zbud"
95 static char *zswap_zpool_type
= ZSWAP_ZPOOL_DEFAULT
;
96 module_param_named(zpool
, zswap_zpool_type
, charp
, 0444);
98 /* zpool is shared by all of zswap backend */
99 static struct zpool
*zswap_pool
;
101 /*********************************
102 * compression functions
103 **********************************/
104 /* per-cpu compression transforms */
105 static struct crypto_comp
* __percpu
*zswap_comp_pcpu_tfms
;
108 ZSWAP_COMPOP_COMPRESS
,
109 ZSWAP_COMPOP_DECOMPRESS
112 static int zswap_comp_op(enum comp_op op
, const u8
*src
, unsigned int slen
,
113 u8
*dst
, unsigned int *dlen
)
115 struct crypto_comp
*tfm
;
118 tfm
= *per_cpu_ptr(zswap_comp_pcpu_tfms
, get_cpu());
120 case ZSWAP_COMPOP_COMPRESS
:
121 ret
= crypto_comp_compress(tfm
, src
, slen
, dst
, dlen
);
123 case ZSWAP_COMPOP_DECOMPRESS
:
124 ret
= crypto_comp_decompress(tfm
, src
, slen
, dst
, dlen
);
134 static int __init
zswap_comp_init(void)
136 if (!crypto_has_comp(zswap_compressor
, 0, 0)) {
137 pr_info("%s compressor not available\n", zswap_compressor
);
138 /* fall back to default compressor */
139 zswap_compressor
= ZSWAP_COMPRESSOR_DEFAULT
;
140 if (!crypto_has_comp(zswap_compressor
, 0, 0))
141 /* can't even load the default compressor */
144 pr_info("using %s compressor\n", zswap_compressor
);
146 /* alloc percpu transforms */
147 zswap_comp_pcpu_tfms
= alloc_percpu(struct crypto_comp
*);
148 if (!zswap_comp_pcpu_tfms
)
153 static void __init
zswap_comp_exit(void)
155 /* free percpu transforms */
156 free_percpu(zswap_comp_pcpu_tfms
);
159 /*********************************
161 **********************************/
165 * This structure contains the metadata for tracking a single compressed
168 * rbnode - links the entry into red-black tree for the appropriate swap type
169 * refcount - the number of outstanding reference to the entry. This is needed
170 * to protect against premature freeing of the entry by code
171 * concurrent calls to load, invalidate, and writeback. The lock
172 * for the zswap_tree structure that contains the entry must
173 * be held while changing the refcount. Since the lock must
174 * be held, there is no reason to also make refcount atomic.
175 * offset - the swap offset for the entry. Index into the red-black tree.
176 * handle - zpool allocation handle that stores the compressed page data
177 * length - the length in bytes of the compressed page data. Needed during
181 struct rb_node rbnode
;
185 unsigned long handle
;
188 struct zswap_header
{
189 swp_entry_t swpentry
;
193 * The tree lock in the zswap_tree struct protects a few things:
195 * - the refcount field of each entry in the tree
198 struct rb_root rbroot
;
202 static struct zswap_tree
*zswap_trees
[MAX_SWAPFILES
];
204 /*********************************
205 * zswap entry functions
206 **********************************/
207 static struct kmem_cache
*zswap_entry_cache
;
209 static int __init
zswap_entry_cache_create(void)
211 zswap_entry_cache
= KMEM_CACHE(zswap_entry
, 0);
212 return zswap_entry_cache
== NULL
;
215 static void __init
zswap_entry_cache_destroy(void)
217 kmem_cache_destroy(zswap_entry_cache
);
220 static struct zswap_entry
*zswap_entry_cache_alloc(gfp_t gfp
)
222 struct zswap_entry
*entry
;
223 entry
= kmem_cache_alloc(zswap_entry_cache
, gfp
);
227 RB_CLEAR_NODE(&entry
->rbnode
);
231 static void zswap_entry_cache_free(struct zswap_entry
*entry
)
233 kmem_cache_free(zswap_entry_cache
, entry
);
236 /*********************************
238 **********************************/
239 static struct zswap_entry
*zswap_rb_search(struct rb_root
*root
, pgoff_t offset
)
241 struct rb_node
*node
= root
->rb_node
;
242 struct zswap_entry
*entry
;
245 entry
= rb_entry(node
, struct zswap_entry
, rbnode
);
246 if (entry
->offset
> offset
)
247 node
= node
->rb_left
;
248 else if (entry
->offset
< offset
)
249 node
= node
->rb_right
;
257 * In the case that a entry with the same offset is found, a pointer to
258 * the existing entry is stored in dupentry and the function returns -EEXIST
260 static int zswap_rb_insert(struct rb_root
*root
, struct zswap_entry
*entry
,
261 struct zswap_entry
**dupentry
)
263 struct rb_node
**link
= &root
->rb_node
, *parent
= NULL
;
264 struct zswap_entry
*myentry
;
268 myentry
= rb_entry(parent
, struct zswap_entry
, rbnode
);
269 if (myentry
->offset
> entry
->offset
)
270 link
= &(*link
)->rb_left
;
271 else if (myentry
->offset
< entry
->offset
)
272 link
= &(*link
)->rb_right
;
278 rb_link_node(&entry
->rbnode
, parent
, link
);
279 rb_insert_color(&entry
->rbnode
, root
);
283 static void zswap_rb_erase(struct rb_root
*root
, struct zswap_entry
*entry
)
285 if (!RB_EMPTY_NODE(&entry
->rbnode
)) {
286 rb_erase(&entry
->rbnode
, root
);
287 RB_CLEAR_NODE(&entry
->rbnode
);
292 * Carries out the common pattern of freeing and entry's zpool allocation,
293 * freeing the entry itself, and decrementing the number of stored pages.
295 static void zswap_free_entry(struct zswap_entry
*entry
)
297 zpool_free(zswap_pool
, entry
->handle
);
298 zswap_entry_cache_free(entry
);
299 atomic_dec(&zswap_stored_pages
);
300 zswap_pool_total_size
= zpool_get_total_size(zswap_pool
);
303 /* caller must hold the tree lock */
304 static void zswap_entry_get(struct zswap_entry
*entry
)
309 /* caller must hold the tree lock
310 * remove from the tree and free it, if nobody reference the entry
312 static void zswap_entry_put(struct zswap_tree
*tree
,
313 struct zswap_entry
*entry
)
315 int refcount
= --entry
->refcount
;
317 BUG_ON(refcount
< 0);
319 zswap_rb_erase(&tree
->rbroot
, entry
);
320 zswap_free_entry(entry
);
324 /* caller must hold the tree lock */
325 static struct zswap_entry
*zswap_entry_find_get(struct rb_root
*root
,
328 struct zswap_entry
*entry
= NULL
;
330 entry
= zswap_rb_search(root
, offset
);
332 zswap_entry_get(entry
);
337 /*********************************
339 **********************************/
340 static DEFINE_PER_CPU(u8
*, zswap_dstmem
);
342 static int __zswap_cpu_notifier(unsigned long action
, unsigned long cpu
)
344 struct crypto_comp
*tfm
;
349 tfm
= crypto_alloc_comp(zswap_compressor
, 0, 0);
351 pr_err("can't allocate compressor transform\n");
354 *per_cpu_ptr(zswap_comp_pcpu_tfms
, cpu
) = tfm
;
355 dst
= kmalloc_node(PAGE_SIZE
* 2, GFP_KERNEL
, cpu_to_node(cpu
));
357 pr_err("can't allocate compressor buffer\n");
358 crypto_free_comp(tfm
);
359 *per_cpu_ptr(zswap_comp_pcpu_tfms
, cpu
) = NULL
;
362 per_cpu(zswap_dstmem
, cpu
) = dst
;
365 case CPU_UP_CANCELED
:
366 tfm
= *per_cpu_ptr(zswap_comp_pcpu_tfms
, cpu
);
368 crypto_free_comp(tfm
);
369 *per_cpu_ptr(zswap_comp_pcpu_tfms
, cpu
) = NULL
;
371 dst
= per_cpu(zswap_dstmem
, cpu
);
373 per_cpu(zswap_dstmem
, cpu
) = NULL
;
381 static int zswap_cpu_notifier(struct notifier_block
*nb
,
382 unsigned long action
, void *pcpu
)
384 unsigned long cpu
= (unsigned long)pcpu
;
385 return __zswap_cpu_notifier(action
, cpu
);
388 static struct notifier_block zswap_cpu_notifier_block
= {
389 .notifier_call
= zswap_cpu_notifier
392 static int __init
zswap_cpu_init(void)
396 cpu_notifier_register_begin();
397 for_each_online_cpu(cpu
)
398 if (__zswap_cpu_notifier(CPU_UP_PREPARE
, cpu
) != NOTIFY_OK
)
400 __register_cpu_notifier(&zswap_cpu_notifier_block
);
401 cpu_notifier_register_done();
405 for_each_online_cpu(cpu
)
406 __zswap_cpu_notifier(CPU_UP_CANCELED
, cpu
);
407 cpu_notifier_register_done();
411 /*********************************
413 **********************************/
414 static bool zswap_is_full(void)
416 return totalram_pages
* zswap_max_pool_percent
/ 100 <
417 DIV_ROUND_UP(zswap_pool_total_size
, PAGE_SIZE
);
420 /*********************************
422 **********************************/
423 /* return enum for zswap_get_swap_cache_page */
424 enum zswap_get_swap_ret
{
426 ZSWAP_SWAPCACHE_EXIST
,
427 ZSWAP_SWAPCACHE_FAIL
,
431 * zswap_get_swap_cache_page
433 * This is an adaption of read_swap_cache_async()
435 * This function tries to find a page with the given swap entry
436 * in the swapper_space address space (the swap cache). If the page
437 * is found, it is returned in retpage. Otherwise, a page is allocated,
438 * added to the swap cache, and returned in retpage.
440 * If success, the swap cache page is returned in retpage
441 * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
442 * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
443 * the new page is added to swapcache and locked
444 * Returns ZSWAP_SWAPCACHE_FAIL on error
446 static int zswap_get_swap_cache_page(swp_entry_t entry
,
447 struct page
**retpage
)
449 bool page_was_allocated
;
451 *retpage
= __read_swap_cache_async(entry
, GFP_KERNEL
,
452 NULL
, 0, &page_was_allocated
);
453 if (page_was_allocated
)
454 return ZSWAP_SWAPCACHE_NEW
;
456 return ZSWAP_SWAPCACHE_FAIL
;
457 return ZSWAP_SWAPCACHE_EXIST
;
461 * Attempts to free an entry by adding a page to the swap cache,
462 * decompressing the entry data into the page, and issuing a
463 * bio write to write the page back to the swap device.
465 * This can be thought of as a "resumed writeback" of the page
466 * to the swap device. We are basically resuming the same swap
467 * writeback path that was intercepted with the frontswap_store()
468 * in the first place. After the page has been decompressed into
469 * the swap cache, the compressed version stored by zswap can be
472 static int zswap_writeback_entry(struct zpool
*pool
, unsigned long handle
)
474 struct zswap_header
*zhdr
;
475 swp_entry_t swpentry
;
476 struct zswap_tree
*tree
;
478 struct zswap_entry
*entry
;
483 struct writeback_control wbc
= {
484 .sync_mode
= WB_SYNC_NONE
,
487 /* extract swpentry from data */
488 zhdr
= zpool_map_handle(pool
, handle
, ZPOOL_MM_RO
);
489 swpentry
= zhdr
->swpentry
; /* here */
490 zpool_unmap_handle(pool
, handle
);
491 tree
= zswap_trees
[swp_type(swpentry
)];
492 offset
= swp_offset(swpentry
);
494 /* find and ref zswap entry */
495 spin_lock(&tree
->lock
);
496 entry
= zswap_entry_find_get(&tree
->rbroot
, offset
);
498 /* entry was invalidated */
499 spin_unlock(&tree
->lock
);
502 spin_unlock(&tree
->lock
);
503 BUG_ON(offset
!= entry
->offset
);
505 /* try to allocate swap cache page */
506 switch (zswap_get_swap_cache_page(swpentry
, &page
)) {
507 case ZSWAP_SWAPCACHE_FAIL
: /* no memory or invalidate happened */
511 case ZSWAP_SWAPCACHE_EXIST
:
512 /* page is already in the swap cache, ignore for now */
513 page_cache_release(page
);
517 case ZSWAP_SWAPCACHE_NEW
: /* page is locked */
520 src
= (u8
*)zpool_map_handle(zswap_pool
, entry
->handle
,
521 ZPOOL_MM_RO
) + sizeof(struct zswap_header
);
522 dst
= kmap_atomic(page
);
523 ret
= zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS
, src
,
524 entry
->length
, dst
, &dlen
);
526 zpool_unmap_handle(zswap_pool
, entry
->handle
);
528 BUG_ON(dlen
!= PAGE_SIZE
);
530 /* page is up to date */
531 SetPageUptodate(page
);
534 /* move it to the tail of the inactive list after end_writeback */
535 SetPageReclaim(page
);
537 /* start writeback */
538 __swap_writepage(page
, &wbc
, end_swap_bio_write
);
539 page_cache_release(page
);
540 zswap_written_back_pages
++;
542 spin_lock(&tree
->lock
);
543 /* drop local reference */
544 zswap_entry_put(tree
, entry
);
547 * There are two possible situations for entry here:
548 * (1) refcount is 1(normal case), entry is valid and on the tree
549 * (2) refcount is 0, entry is freed and not on the tree
550 * because invalidate happened during writeback
551 * search the tree and free the entry if find entry
553 if (entry
== zswap_rb_search(&tree
->rbroot
, offset
))
554 zswap_entry_put(tree
, entry
);
555 spin_unlock(&tree
->lock
);
560 * if we get here due to ZSWAP_SWAPCACHE_EXIST
561 * a load may happening concurrently
562 * it is safe and okay to not free the entry
563 * if we free the entry in the following put
564 * it it either okay to return !0
567 spin_lock(&tree
->lock
);
568 zswap_entry_put(tree
, entry
);
569 spin_unlock(&tree
->lock
);
575 /*********************************
577 **********************************/
578 /* attempts to compress and store an single page */
579 static int zswap_frontswap_store(unsigned type
, pgoff_t offset
,
582 struct zswap_tree
*tree
= zswap_trees
[type
];
583 struct zswap_entry
*entry
, *dupentry
;
585 unsigned int dlen
= PAGE_SIZE
, len
;
586 unsigned long handle
;
589 struct zswap_header
*zhdr
;
591 if (!zswap_enabled
|| !tree
) {
596 /* reclaim space if needed */
597 if (zswap_is_full()) {
598 zswap_pool_limit_hit
++;
599 if (zpool_shrink(zswap_pool
, 1, NULL
)) {
600 zswap_reject_reclaim_fail
++;
607 entry
= zswap_entry_cache_alloc(GFP_KERNEL
);
609 zswap_reject_kmemcache_fail
++;
615 dst
= get_cpu_var(zswap_dstmem
);
616 src
= kmap_atomic(page
);
617 ret
= zswap_comp_op(ZSWAP_COMPOP_COMPRESS
, src
, PAGE_SIZE
, dst
, &dlen
);
625 len
= dlen
+ sizeof(struct zswap_header
);
626 ret
= zpool_malloc(zswap_pool
, len
, __GFP_NORETRY
| __GFP_NOWARN
,
628 if (ret
== -ENOSPC
) {
629 zswap_reject_compress_poor
++;
633 zswap_reject_alloc_fail
++;
636 zhdr
= zpool_map_handle(zswap_pool
, handle
, ZPOOL_MM_RW
);
637 zhdr
->swpentry
= swp_entry(type
, offset
);
638 buf
= (u8
*)(zhdr
+ 1);
639 memcpy(buf
, dst
, dlen
);
640 zpool_unmap_handle(zswap_pool
, handle
);
641 put_cpu_var(zswap_dstmem
);
644 entry
->offset
= offset
;
645 entry
->handle
= handle
;
646 entry
->length
= dlen
;
649 spin_lock(&tree
->lock
);
651 ret
= zswap_rb_insert(&tree
->rbroot
, entry
, &dupentry
);
652 if (ret
== -EEXIST
) {
653 zswap_duplicate_entry
++;
654 /* remove from rbtree */
655 zswap_rb_erase(&tree
->rbroot
, dupentry
);
656 zswap_entry_put(tree
, dupentry
);
658 } while (ret
== -EEXIST
);
659 spin_unlock(&tree
->lock
);
662 atomic_inc(&zswap_stored_pages
);
663 zswap_pool_total_size
= zpool_get_total_size(zswap_pool
);
668 put_cpu_var(zswap_dstmem
);
669 zswap_entry_cache_free(entry
);
675 * returns 0 if the page was successfully decompressed
676 * return -1 on entry not found or error
678 static int zswap_frontswap_load(unsigned type
, pgoff_t offset
,
681 struct zswap_tree
*tree
= zswap_trees
[type
];
682 struct zswap_entry
*entry
;
688 spin_lock(&tree
->lock
);
689 entry
= zswap_entry_find_get(&tree
->rbroot
, offset
);
691 /* entry was written back */
692 spin_unlock(&tree
->lock
);
695 spin_unlock(&tree
->lock
);
699 src
= (u8
*)zpool_map_handle(zswap_pool
, entry
->handle
,
700 ZPOOL_MM_RO
) + sizeof(struct zswap_header
);
701 dst
= kmap_atomic(page
);
702 ret
= zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS
, src
, entry
->length
,
705 zpool_unmap_handle(zswap_pool
, entry
->handle
);
708 spin_lock(&tree
->lock
);
709 zswap_entry_put(tree
, entry
);
710 spin_unlock(&tree
->lock
);
715 /* frees an entry in zswap */
716 static void zswap_frontswap_invalidate_page(unsigned type
, pgoff_t offset
)
718 struct zswap_tree
*tree
= zswap_trees
[type
];
719 struct zswap_entry
*entry
;
722 spin_lock(&tree
->lock
);
723 entry
= zswap_rb_search(&tree
->rbroot
, offset
);
725 /* entry was written back */
726 spin_unlock(&tree
->lock
);
730 /* remove from rbtree */
731 zswap_rb_erase(&tree
->rbroot
, entry
);
733 /* drop the initial reference from entry creation */
734 zswap_entry_put(tree
, entry
);
736 spin_unlock(&tree
->lock
);
739 /* frees all zswap entries for the given swap type */
740 static void zswap_frontswap_invalidate_area(unsigned type
)
742 struct zswap_tree
*tree
= zswap_trees
[type
];
743 struct zswap_entry
*entry
, *n
;
748 /* walk the tree and free everything */
749 spin_lock(&tree
->lock
);
750 rbtree_postorder_for_each_entry_safe(entry
, n
, &tree
->rbroot
, rbnode
)
751 zswap_free_entry(entry
);
752 tree
->rbroot
= RB_ROOT
;
753 spin_unlock(&tree
->lock
);
755 zswap_trees
[type
] = NULL
;
758 static const struct zpool_ops zswap_zpool_ops
= {
759 .evict
= zswap_writeback_entry
762 static void zswap_frontswap_init(unsigned type
)
764 struct zswap_tree
*tree
;
766 tree
= kzalloc(sizeof(struct zswap_tree
), GFP_KERNEL
);
768 pr_err("alloc failed, zswap disabled for swap type %d\n", type
);
772 tree
->rbroot
= RB_ROOT
;
773 spin_lock_init(&tree
->lock
);
774 zswap_trees
[type
] = tree
;
777 static struct frontswap_ops zswap_frontswap_ops
= {
778 .store
= zswap_frontswap_store
,
779 .load
= zswap_frontswap_load
,
780 .invalidate_page
= zswap_frontswap_invalidate_page
,
781 .invalidate_area
= zswap_frontswap_invalidate_area
,
782 .init
= zswap_frontswap_init
785 /*********************************
787 **********************************/
788 #ifdef CONFIG_DEBUG_FS
789 #include <linux/debugfs.h>
791 static struct dentry
*zswap_debugfs_root
;
793 static int __init
zswap_debugfs_init(void)
795 if (!debugfs_initialized())
798 zswap_debugfs_root
= debugfs_create_dir("zswap", NULL
);
799 if (!zswap_debugfs_root
)
802 debugfs_create_u64("pool_limit_hit", S_IRUGO
,
803 zswap_debugfs_root
, &zswap_pool_limit_hit
);
804 debugfs_create_u64("reject_reclaim_fail", S_IRUGO
,
805 zswap_debugfs_root
, &zswap_reject_reclaim_fail
);
806 debugfs_create_u64("reject_alloc_fail", S_IRUGO
,
807 zswap_debugfs_root
, &zswap_reject_alloc_fail
);
808 debugfs_create_u64("reject_kmemcache_fail", S_IRUGO
,
809 zswap_debugfs_root
, &zswap_reject_kmemcache_fail
);
810 debugfs_create_u64("reject_compress_poor", S_IRUGO
,
811 zswap_debugfs_root
, &zswap_reject_compress_poor
);
812 debugfs_create_u64("written_back_pages", S_IRUGO
,
813 zswap_debugfs_root
, &zswap_written_back_pages
);
814 debugfs_create_u64("duplicate_entry", S_IRUGO
,
815 zswap_debugfs_root
, &zswap_duplicate_entry
);
816 debugfs_create_u64("pool_total_size", S_IRUGO
,
817 zswap_debugfs_root
, &zswap_pool_total_size
);
818 debugfs_create_atomic_t("stored_pages", S_IRUGO
,
819 zswap_debugfs_root
, &zswap_stored_pages
);
824 static void __exit
zswap_debugfs_exit(void)
826 debugfs_remove_recursive(zswap_debugfs_root
);
829 static int __init
zswap_debugfs_init(void)
834 static void __exit
zswap_debugfs_exit(void) { }
837 /*********************************
838 * module init and exit
839 **********************************/
840 static int __init
init_zswap(void)
842 gfp_t gfp
= __GFP_NORETRY
| __GFP_NOWARN
;
844 pr_info("loading zswap\n");
846 zswap_pool
= zpool_create_pool(zswap_zpool_type
, "zswap", gfp
,
848 if (!zswap_pool
&& strcmp(zswap_zpool_type
, ZSWAP_ZPOOL_DEFAULT
)) {
849 pr_info("%s zpool not available\n", zswap_zpool_type
);
850 zswap_zpool_type
= ZSWAP_ZPOOL_DEFAULT
;
851 zswap_pool
= zpool_create_pool(zswap_zpool_type
, "zswap", gfp
,
855 pr_err("%s zpool not available\n", zswap_zpool_type
);
856 pr_err("zpool creation failed\n");
859 pr_info("using %s pool\n", zswap_zpool_type
);
861 if (zswap_entry_cache_create()) {
862 pr_err("entry cache creation failed\n");
865 if (zswap_comp_init()) {
866 pr_err("compressor initialization failed\n");
869 if (zswap_cpu_init()) {
870 pr_err("per-cpu initialization failed\n");
874 frontswap_register_ops(&zswap_frontswap_ops
);
875 if (zswap_debugfs_init())
876 pr_warn("debugfs initialization failed\n");
881 zswap_entry_cache_destroy();
883 zpool_destroy_pool(zswap_pool
);
887 /* must be late so crypto has time to come up */
888 late_initcall(init_zswap
);
890 MODULE_LICENSE("GPL");
891 MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
892 MODULE_DESCRIPTION("Compressed cache for swap pages");