2 * Compressed RAM block device
4 * Copyright (C) 2008, 2009, 2010 Nitin Gupta
5 * 2012, 2013 Minchan Kim
7 * This code is released using a dual license strategy: BSD/GPL
8 * You can choose the licence that better fits your requirements.
10 * Released under the terms of 3-clause BSD License
11 * Released under the terms of GNU General Public License Version 2.0
15 #define KMSG_COMPONENT "zram"
16 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
18 #include <linux/module.h>
19 #include <linux/kernel.h>
20 #include <linux/bio.h>
21 #include <linux/bitops.h>
22 #include <linux/blkdev.h>
23 #include <linux/buffer_head.h>
24 #include <linux/device.h>
25 #include <linux/genhd.h>
26 #include <linux/highmem.h>
27 #include <linux/slab.h>
28 #include <linux/string.h>
29 #include <linux/vmalloc.h>
30 #include <linux/err.h>
35 static int zram_major
;
36 static struct zram
*zram_devices
;
37 static const char *default_compressor
= "lzo";
39 /* Module params (documentation at end) */
40 static unsigned int num_devices
= 1;
42 static inline void deprecated_attr_warn(const char *name
)
44 pr_warn_once("%d (%s) Attribute %s (and others) will be removed. %s\n",
48 "See zram documentation.");
51 #define ZRAM_ATTR_RO(name) \
52 static ssize_t name##_show(struct device *d, \
53 struct device_attribute *attr, char *b) \
55 struct zram *zram = dev_to_zram(d); \
57 deprecated_attr_warn(__stringify(name)); \
58 return scnprintf(b, PAGE_SIZE, "%llu\n", \
59 (u64)atomic64_read(&zram->stats.name)); \
61 static DEVICE_ATTR_RO(name);
63 static inline bool init_done(struct zram
*zram
)
65 return zram
->disksize
;
68 static inline struct zram
*dev_to_zram(struct device
*dev
)
70 return (struct zram
*)dev_to_disk(dev
)->private_data
;
73 static ssize_t
compact_store(struct device
*dev
,
74 struct device_attribute
*attr
, const char *buf
, size_t len
)
76 unsigned long nr_migrated
;
77 struct zram
*zram
= dev_to_zram(dev
);
78 struct zram_meta
*meta
;
80 down_read(&zram
->init_lock
);
81 if (!init_done(zram
)) {
82 up_read(&zram
->init_lock
);
87 nr_migrated
= zs_compact(meta
->mem_pool
);
88 atomic64_add(nr_migrated
, &zram
->stats
.num_migrated
);
89 up_read(&zram
->init_lock
);
94 static ssize_t
disksize_show(struct device
*dev
,
95 struct device_attribute
*attr
, char *buf
)
97 struct zram
*zram
= dev_to_zram(dev
);
99 return scnprintf(buf
, PAGE_SIZE
, "%llu\n", zram
->disksize
);
102 static ssize_t
initstate_show(struct device
*dev
,
103 struct device_attribute
*attr
, char *buf
)
106 struct zram
*zram
= dev_to_zram(dev
);
108 down_read(&zram
->init_lock
);
109 val
= init_done(zram
);
110 up_read(&zram
->init_lock
);
112 return scnprintf(buf
, PAGE_SIZE
, "%u\n", val
);
115 static ssize_t
orig_data_size_show(struct device
*dev
,
116 struct device_attribute
*attr
, char *buf
)
118 struct zram
*zram
= dev_to_zram(dev
);
120 deprecated_attr_warn("orig_data_size");
121 return scnprintf(buf
, PAGE_SIZE
, "%llu\n",
122 (u64
)(atomic64_read(&zram
->stats
.pages_stored
)) << PAGE_SHIFT
);
125 static ssize_t
mem_used_total_show(struct device
*dev
,
126 struct device_attribute
*attr
, char *buf
)
129 struct zram
*zram
= dev_to_zram(dev
);
131 deprecated_attr_warn("mem_used_total");
132 down_read(&zram
->init_lock
);
133 if (init_done(zram
)) {
134 struct zram_meta
*meta
= zram
->meta
;
135 val
= zs_get_total_pages(meta
->mem_pool
);
137 up_read(&zram
->init_lock
);
139 return scnprintf(buf
, PAGE_SIZE
, "%llu\n", val
<< PAGE_SHIFT
);
142 static ssize_t
max_comp_streams_show(struct device
*dev
,
143 struct device_attribute
*attr
, char *buf
)
146 struct zram
*zram
= dev_to_zram(dev
);
148 down_read(&zram
->init_lock
);
149 val
= zram
->max_comp_streams
;
150 up_read(&zram
->init_lock
);
152 return scnprintf(buf
, PAGE_SIZE
, "%d\n", val
);
155 static ssize_t
mem_limit_show(struct device
*dev
,
156 struct device_attribute
*attr
, char *buf
)
159 struct zram
*zram
= dev_to_zram(dev
);
161 deprecated_attr_warn("mem_limit");
162 down_read(&zram
->init_lock
);
163 val
= zram
->limit_pages
;
164 up_read(&zram
->init_lock
);
166 return scnprintf(buf
, PAGE_SIZE
, "%llu\n", val
<< PAGE_SHIFT
);
169 static ssize_t
mem_limit_store(struct device
*dev
,
170 struct device_attribute
*attr
, const char *buf
, size_t len
)
174 struct zram
*zram
= dev_to_zram(dev
);
176 limit
= memparse(buf
, &tmp
);
177 if (buf
== tmp
) /* no chars parsed, invalid input */
180 down_write(&zram
->init_lock
);
181 zram
->limit_pages
= PAGE_ALIGN(limit
) >> PAGE_SHIFT
;
182 up_write(&zram
->init_lock
);
187 static ssize_t
mem_used_max_show(struct device
*dev
,
188 struct device_attribute
*attr
, char *buf
)
191 struct zram
*zram
= dev_to_zram(dev
);
193 deprecated_attr_warn("mem_used_max");
194 down_read(&zram
->init_lock
);
196 val
= atomic_long_read(&zram
->stats
.max_used_pages
);
197 up_read(&zram
->init_lock
);
199 return scnprintf(buf
, PAGE_SIZE
, "%llu\n", val
<< PAGE_SHIFT
);
202 static ssize_t
mem_used_max_store(struct device
*dev
,
203 struct device_attribute
*attr
, const char *buf
, size_t len
)
207 struct zram
*zram
= dev_to_zram(dev
);
209 err
= kstrtoul(buf
, 10, &val
);
213 down_read(&zram
->init_lock
);
214 if (init_done(zram
)) {
215 struct zram_meta
*meta
= zram
->meta
;
216 atomic_long_set(&zram
->stats
.max_used_pages
,
217 zs_get_total_pages(meta
->mem_pool
));
219 up_read(&zram
->init_lock
);
224 static ssize_t
max_comp_streams_store(struct device
*dev
,
225 struct device_attribute
*attr
, const char *buf
, size_t len
)
228 struct zram
*zram
= dev_to_zram(dev
);
231 ret
= kstrtoint(buf
, 0, &num
);
237 down_write(&zram
->init_lock
);
238 if (init_done(zram
)) {
239 if (!zcomp_set_max_streams(zram
->comp
, num
)) {
240 pr_info("Cannot change max compression streams\n");
246 zram
->max_comp_streams
= num
;
249 up_write(&zram
->init_lock
);
253 static ssize_t
comp_algorithm_show(struct device
*dev
,
254 struct device_attribute
*attr
, char *buf
)
257 struct zram
*zram
= dev_to_zram(dev
);
259 down_read(&zram
->init_lock
);
260 sz
= zcomp_available_show(zram
->compressor
, buf
);
261 up_read(&zram
->init_lock
);
266 static ssize_t
comp_algorithm_store(struct device
*dev
,
267 struct device_attribute
*attr
, const char *buf
, size_t len
)
269 struct zram
*zram
= dev_to_zram(dev
);
270 down_write(&zram
->init_lock
);
271 if (init_done(zram
)) {
272 up_write(&zram
->init_lock
);
273 pr_info("Can't change algorithm for initialized device\n");
276 strlcpy(zram
->compressor
, buf
, sizeof(zram
->compressor
));
277 up_write(&zram
->init_lock
);
281 /* flag operations needs meta->tb_lock */
282 static int zram_test_flag(struct zram_meta
*meta
, u32 index
,
283 enum zram_pageflags flag
)
285 return meta
->table
[index
].value
& BIT(flag
);
288 static void zram_set_flag(struct zram_meta
*meta
, u32 index
,
289 enum zram_pageflags flag
)
291 meta
->table
[index
].value
|= BIT(flag
);
294 static void zram_clear_flag(struct zram_meta
*meta
, u32 index
,
295 enum zram_pageflags flag
)
297 meta
->table
[index
].value
&= ~BIT(flag
);
300 static size_t zram_get_obj_size(struct zram_meta
*meta
, u32 index
)
302 return meta
->table
[index
].value
& (BIT(ZRAM_FLAG_SHIFT
) - 1);
305 static void zram_set_obj_size(struct zram_meta
*meta
,
306 u32 index
, size_t size
)
308 unsigned long flags
= meta
->table
[index
].value
>> ZRAM_FLAG_SHIFT
;
310 meta
->table
[index
].value
= (flags
<< ZRAM_FLAG_SHIFT
) | size
;
313 static inline int is_partial_io(struct bio_vec
*bvec
)
315 return bvec
->bv_len
!= PAGE_SIZE
;
319 * Check if request is within bounds and aligned on zram logical blocks.
321 static inline int valid_io_request(struct zram
*zram
,
322 sector_t start
, unsigned int size
)
326 /* unaligned request */
327 if (unlikely(start
& (ZRAM_SECTOR_PER_LOGICAL_BLOCK
- 1)))
329 if (unlikely(size
& (ZRAM_LOGICAL_BLOCK_SIZE
- 1)))
332 end
= start
+ (size
>> SECTOR_SHIFT
);
333 bound
= zram
->disksize
>> SECTOR_SHIFT
;
334 /* out of range range */
335 if (unlikely(start
>= bound
|| end
> bound
|| start
> end
))
338 /* I/O request is valid */
342 static void zram_meta_free(struct zram_meta
*meta
, u64 disksize
)
344 size_t num_pages
= disksize
>> PAGE_SHIFT
;
347 /* Free all pages that are still in this zram device */
348 for (index
= 0; index
< num_pages
; index
++) {
349 unsigned long handle
= meta
->table
[index
].handle
;
354 zs_free(meta
->mem_pool
, handle
);
357 zs_destroy_pool(meta
->mem_pool
);
362 static struct zram_meta
*zram_meta_alloc(int device_id
, u64 disksize
)
366 struct zram_meta
*meta
= kmalloc(sizeof(*meta
), GFP_KERNEL
);
371 num_pages
= disksize
>> PAGE_SHIFT
;
372 meta
->table
= vzalloc(num_pages
* sizeof(*meta
->table
));
374 pr_err("Error allocating zram address table\n");
378 snprintf(pool_name
, sizeof(pool_name
), "zram%d", device_id
);
379 meta
->mem_pool
= zs_create_pool(pool_name
, GFP_NOIO
| __GFP_HIGHMEM
);
380 if (!meta
->mem_pool
) {
381 pr_err("Error creating memory pool\n");
393 static inline bool zram_meta_get(struct zram
*zram
)
395 if (atomic_inc_not_zero(&zram
->refcount
))
400 static inline void zram_meta_put(struct zram
*zram
)
402 atomic_dec(&zram
->refcount
);
405 static void update_position(u32
*index
, int *offset
, struct bio_vec
*bvec
)
407 if (*offset
+ bvec
->bv_len
>= PAGE_SIZE
)
409 *offset
= (*offset
+ bvec
->bv_len
) % PAGE_SIZE
;
412 static int page_zero_filled(void *ptr
)
417 page
= (unsigned long *)ptr
;
419 for (pos
= 0; pos
!= PAGE_SIZE
/ sizeof(*page
); pos
++) {
427 static void handle_zero_page(struct bio_vec
*bvec
)
429 struct page
*page
= bvec
->bv_page
;
432 user_mem
= kmap_atomic(page
);
433 if (is_partial_io(bvec
))
434 memset(user_mem
+ bvec
->bv_offset
, 0, bvec
->bv_len
);
436 clear_page(user_mem
);
437 kunmap_atomic(user_mem
);
439 flush_dcache_page(page
);
444 * To protect concurrent access to the same index entry,
445 * caller should hold this table index entry's bit_spinlock to
446 * indicate this index entry is accessing.
448 static void zram_free_page(struct zram
*zram
, size_t index
)
450 struct zram_meta
*meta
= zram
->meta
;
451 unsigned long handle
= meta
->table
[index
].handle
;
453 if (unlikely(!handle
)) {
455 * No memory is allocated for zero filled pages.
456 * Simply clear zero page flag.
458 if (zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
459 zram_clear_flag(meta
, index
, ZRAM_ZERO
);
460 atomic64_dec(&zram
->stats
.zero_pages
);
465 zs_free(meta
->mem_pool
, handle
);
467 atomic64_sub(zram_get_obj_size(meta
, index
),
468 &zram
->stats
.compr_data_size
);
469 atomic64_dec(&zram
->stats
.pages_stored
);
471 meta
->table
[index
].handle
= 0;
472 zram_set_obj_size(meta
, index
, 0);
475 static int zram_decompress_page(struct zram
*zram
, char *mem
, u32 index
)
479 struct zram_meta
*meta
= zram
->meta
;
480 unsigned long handle
;
483 bit_spin_lock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
484 handle
= meta
->table
[index
].handle
;
485 size
= zram_get_obj_size(meta
, index
);
487 if (!handle
|| zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
488 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
493 cmem
= zs_map_object(meta
->mem_pool
, handle
, ZS_MM_RO
);
494 if (size
== PAGE_SIZE
)
495 copy_page(mem
, cmem
);
497 ret
= zcomp_decompress(zram
->comp
, cmem
, size
, mem
);
498 zs_unmap_object(meta
->mem_pool
, handle
);
499 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
501 /* Should NEVER happen. Return bio error if it does. */
503 pr_err("Decompression failed! err=%d, page=%u\n", ret
, index
);
510 static int zram_bvec_read(struct zram
*zram
, struct bio_vec
*bvec
,
511 u32 index
, int offset
)
515 unsigned char *user_mem
, *uncmem
= NULL
;
516 struct zram_meta
*meta
= zram
->meta
;
517 page
= bvec
->bv_page
;
519 bit_spin_lock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
520 if (unlikely(!meta
->table
[index
].handle
) ||
521 zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
522 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
523 handle_zero_page(bvec
);
526 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
528 if (is_partial_io(bvec
))
529 /* Use a temporary buffer to decompress the page */
530 uncmem
= kmalloc(PAGE_SIZE
, GFP_NOIO
);
532 user_mem
= kmap_atomic(page
);
533 if (!is_partial_io(bvec
))
537 pr_info("Unable to allocate temp memory\n");
542 ret
= zram_decompress_page(zram
, uncmem
, index
);
543 /* Should NEVER happen. Return bio error if it does. */
547 if (is_partial_io(bvec
))
548 memcpy(user_mem
+ bvec
->bv_offset
, uncmem
+ offset
,
551 flush_dcache_page(page
);
554 kunmap_atomic(user_mem
);
555 if (is_partial_io(bvec
))
560 static inline void update_used_max(struct zram
*zram
,
561 const unsigned long pages
)
563 unsigned long old_max
, cur_max
;
565 old_max
= atomic_long_read(&zram
->stats
.max_used_pages
);
570 old_max
= atomic_long_cmpxchg(
571 &zram
->stats
.max_used_pages
, cur_max
, pages
);
572 } while (old_max
!= cur_max
);
575 static int zram_bvec_write(struct zram
*zram
, struct bio_vec
*bvec
, u32 index
,
580 unsigned long handle
;
582 unsigned char *user_mem
, *cmem
, *src
, *uncmem
= NULL
;
583 struct zram_meta
*meta
= zram
->meta
;
584 struct zcomp_strm
*zstrm
;
586 unsigned long alloced_pages
;
588 page
= bvec
->bv_page
;
589 if (is_partial_io(bvec
)) {
591 * This is a partial IO. We need to read the full page
592 * before to write the changes.
594 uncmem
= kmalloc(PAGE_SIZE
, GFP_NOIO
);
599 ret
= zram_decompress_page(zram
, uncmem
, index
);
604 zstrm
= zcomp_strm_find(zram
->comp
);
606 user_mem
= kmap_atomic(page
);
608 if (is_partial_io(bvec
)) {
609 memcpy(uncmem
+ offset
, user_mem
+ bvec
->bv_offset
,
611 kunmap_atomic(user_mem
);
617 if (page_zero_filled(uncmem
)) {
619 kunmap_atomic(user_mem
);
620 /* Free memory associated with this sector now. */
621 bit_spin_lock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
622 zram_free_page(zram
, index
);
623 zram_set_flag(meta
, index
, ZRAM_ZERO
);
624 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
626 atomic64_inc(&zram
->stats
.zero_pages
);
631 ret
= zcomp_compress(zram
->comp
, zstrm
, uncmem
, &clen
);
632 if (!is_partial_io(bvec
)) {
633 kunmap_atomic(user_mem
);
639 pr_err("Compression failed! err=%d\n", ret
);
643 if (unlikely(clen
> max_zpage_size
)) {
645 if (is_partial_io(bvec
))
649 handle
= zs_malloc(meta
->mem_pool
, clen
);
651 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
657 alloced_pages
= zs_get_total_pages(meta
->mem_pool
);
658 if (zram
->limit_pages
&& alloced_pages
> zram
->limit_pages
) {
659 zs_free(meta
->mem_pool
, handle
);
664 update_used_max(zram
, alloced_pages
);
666 cmem
= zs_map_object(meta
->mem_pool
, handle
, ZS_MM_WO
);
668 if ((clen
== PAGE_SIZE
) && !is_partial_io(bvec
)) {
669 src
= kmap_atomic(page
);
670 copy_page(cmem
, src
);
673 memcpy(cmem
, src
, clen
);
676 zcomp_strm_release(zram
->comp
, zstrm
);
678 zs_unmap_object(meta
->mem_pool
, handle
);
681 * Free memory associated with this sector
682 * before overwriting unused sectors.
684 bit_spin_lock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
685 zram_free_page(zram
, index
);
687 meta
->table
[index
].handle
= handle
;
688 zram_set_obj_size(meta
, index
, clen
);
689 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
692 atomic64_add(clen
, &zram
->stats
.compr_data_size
);
693 atomic64_inc(&zram
->stats
.pages_stored
);
696 zcomp_strm_release(zram
->comp
, zstrm
);
697 if (is_partial_io(bvec
))
702 static int zram_bvec_rw(struct zram
*zram
, struct bio_vec
*bvec
, u32 index
,
705 unsigned long start_time
= jiffies
;
708 generic_start_io_acct(rw
, bvec
->bv_len
>> SECTOR_SHIFT
,
712 atomic64_inc(&zram
->stats
.num_reads
);
713 ret
= zram_bvec_read(zram
, bvec
, index
, offset
);
715 atomic64_inc(&zram
->stats
.num_writes
);
716 ret
= zram_bvec_write(zram
, bvec
, index
, offset
);
719 generic_end_io_acct(rw
, &zram
->disk
->part0
, start_time
);
723 atomic64_inc(&zram
->stats
.failed_reads
);
725 atomic64_inc(&zram
->stats
.failed_writes
);
732 * zram_bio_discard - handler on discard request
733 * @index: physical block index in PAGE_SIZE units
734 * @offset: byte offset within physical block
736 static void zram_bio_discard(struct zram
*zram
, u32 index
,
737 int offset
, struct bio
*bio
)
739 size_t n
= bio
->bi_iter
.bi_size
;
740 struct zram_meta
*meta
= zram
->meta
;
743 * zram manages data in physical block size units. Because logical block
744 * size isn't identical with physical block size on some arch, we
745 * could get a discard request pointing to a specific offset within a
746 * certain physical block. Although we can handle this request by
747 * reading that physiclal block and decompressing and partially zeroing
748 * and re-compressing and then re-storing it, this isn't reasonable
749 * because our intent with a discard request is to save memory. So
750 * skipping this logical block is appropriate here.
753 if (n
<= (PAGE_SIZE
- offset
))
756 n
-= (PAGE_SIZE
- offset
);
760 while (n
>= PAGE_SIZE
) {
761 bit_spin_lock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
762 zram_free_page(zram
, index
);
763 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
764 atomic64_inc(&zram
->stats
.notify_free
);
770 static void zram_reset_device(struct zram
*zram
)
772 struct zram_meta
*meta
;
776 down_write(&zram
->init_lock
);
778 zram
->limit_pages
= 0;
780 if (!init_done(zram
)) {
781 up_write(&zram
->init_lock
);
787 disksize
= zram
->disksize
;
789 * Refcount will go down to 0 eventually and r/w handler
790 * cannot handle further I/O so it will bail out by
791 * check zram_meta_get.
795 * We want to free zram_meta in process context to avoid
796 * deadlock between reclaim path and any other locks.
798 wait_event(zram
->io_done
, atomic_read(&zram
->refcount
) == 0);
801 memset(&zram
->stats
, 0, sizeof(zram
->stats
));
803 zram
->max_comp_streams
= 1;
805 set_capacity(zram
->disk
, 0);
806 part_stat_set_all(&zram
->disk
->part0
, 0);
808 up_write(&zram
->init_lock
);
809 /* I/O operation under all of CPU are done so let's free */
810 zram_meta_free(meta
, disksize
);
814 static ssize_t
disksize_store(struct device
*dev
,
815 struct device_attribute
*attr
, const char *buf
, size_t len
)
819 struct zram_meta
*meta
;
820 struct zram
*zram
= dev_to_zram(dev
);
823 disksize
= memparse(buf
, NULL
);
827 disksize
= PAGE_ALIGN(disksize
);
828 meta
= zram_meta_alloc(zram
->disk
->first_minor
, disksize
);
832 comp
= zcomp_create(zram
->compressor
, zram
->max_comp_streams
);
834 pr_info("Cannot initialise %s compressing backend\n",
840 down_write(&zram
->init_lock
);
841 if (init_done(zram
)) {
842 pr_info("Cannot change disksize for initialized device\n");
844 goto out_destroy_comp
;
847 init_waitqueue_head(&zram
->io_done
);
848 atomic_set(&zram
->refcount
, 1);
851 zram
->disksize
= disksize
;
852 set_capacity(zram
->disk
, zram
->disksize
>> SECTOR_SHIFT
);
853 up_write(&zram
->init_lock
);
856 * Revalidate disk out of the init_lock to avoid lockdep splat.
857 * It's okay because disk's capacity is protected by init_lock
858 * so that revalidate_disk always sees up-to-date capacity.
860 revalidate_disk(zram
->disk
);
865 up_write(&zram
->init_lock
);
868 zram_meta_free(meta
, disksize
);
872 static ssize_t
reset_store(struct device
*dev
,
873 struct device_attribute
*attr
, const char *buf
, size_t len
)
876 unsigned short do_reset
;
878 struct block_device
*bdev
;
880 zram
= dev_to_zram(dev
);
881 bdev
= bdget_disk(zram
->disk
, 0);
886 mutex_lock(&bdev
->bd_mutex
);
887 /* Do not reset an active device! */
888 if (bdev
->bd_openers
) {
893 ret
= kstrtou16(buf
, 10, &do_reset
);
902 /* Make sure all pending I/O is finished */
904 zram_reset_device(zram
);
906 mutex_unlock(&bdev
->bd_mutex
);
907 revalidate_disk(zram
->disk
);
913 mutex_unlock(&bdev
->bd_mutex
);
918 static void __zram_make_request(struct zram
*zram
, struct bio
*bio
)
923 struct bvec_iter iter
;
925 index
= bio
->bi_iter
.bi_sector
>> SECTORS_PER_PAGE_SHIFT
;
926 offset
= (bio
->bi_iter
.bi_sector
&
927 (SECTORS_PER_PAGE
- 1)) << SECTOR_SHIFT
;
929 if (unlikely(bio
->bi_rw
& REQ_DISCARD
)) {
930 zram_bio_discard(zram
, index
, offset
, bio
);
935 rw
= bio_data_dir(bio
);
936 bio_for_each_segment(bvec
, bio
, iter
) {
937 int max_transfer_size
= PAGE_SIZE
- offset
;
939 if (bvec
.bv_len
> max_transfer_size
) {
941 * zram_bvec_rw() can only make operation on a single
942 * zram page. Split the bio vector.
946 bv
.bv_page
= bvec
.bv_page
;
947 bv
.bv_len
= max_transfer_size
;
948 bv
.bv_offset
= bvec
.bv_offset
;
950 if (zram_bvec_rw(zram
, &bv
, index
, offset
, rw
) < 0)
953 bv
.bv_len
= bvec
.bv_len
- max_transfer_size
;
954 bv
.bv_offset
+= max_transfer_size
;
955 if (zram_bvec_rw(zram
, &bv
, index
+ 1, 0, rw
) < 0)
958 if (zram_bvec_rw(zram
, &bvec
, index
, offset
, rw
) < 0)
961 update_position(&index
, &offset
, &bvec
);
964 set_bit(BIO_UPTODATE
, &bio
->bi_flags
);
973 * Handler function for all zram I/O requests.
975 static void zram_make_request(struct request_queue
*queue
, struct bio
*bio
)
977 struct zram
*zram
= queue
->queuedata
;
979 if (unlikely(!zram_meta_get(zram
)))
982 if (!valid_io_request(zram
, bio
->bi_iter
.bi_sector
,
983 bio
->bi_iter
.bi_size
)) {
984 atomic64_inc(&zram
->stats
.invalid_io
);
988 __zram_make_request(zram
, bio
);
997 static void zram_slot_free_notify(struct block_device
*bdev
,
1001 struct zram_meta
*meta
;
1003 zram
= bdev
->bd_disk
->private_data
;
1006 bit_spin_lock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
1007 zram_free_page(zram
, index
);
1008 bit_spin_unlock(ZRAM_ACCESS
, &meta
->table
[index
].value
);
1009 atomic64_inc(&zram
->stats
.notify_free
);
1012 static int zram_rw_page(struct block_device
*bdev
, sector_t sector
,
1013 struct page
*page
, int rw
)
1015 int offset
, err
= -EIO
;
1020 zram
= bdev
->bd_disk
->private_data
;
1021 if (unlikely(!zram_meta_get(zram
)))
1024 if (!valid_io_request(zram
, sector
, PAGE_SIZE
)) {
1025 atomic64_inc(&zram
->stats
.invalid_io
);
1030 index
= sector
>> SECTORS_PER_PAGE_SHIFT
;
1031 offset
= sector
& (SECTORS_PER_PAGE
- 1) << SECTOR_SHIFT
;
1034 bv
.bv_len
= PAGE_SIZE
;
1037 err
= zram_bvec_rw(zram
, &bv
, index
, offset
, rw
);
1039 zram_meta_put(zram
);
1042 * If I/O fails, just return error(ie, non-zero) without
1043 * calling page_endio.
1044 * It causes resubmit the I/O with bio request by upper functions
1045 * of rw_page(e.g., swap_readpage, __swap_writepage) and
1046 * bio->bi_end_io does things to handle the error
1047 * (e.g., SetPageError, set_page_dirty and extra works).
1050 page_endio(page
, rw
, 0);
1054 static const struct block_device_operations zram_devops
= {
1055 .swap_slot_free_notify
= zram_slot_free_notify
,
1056 .rw_page
= zram_rw_page
,
1057 .owner
= THIS_MODULE
1060 static DEVICE_ATTR_WO(compact
);
1061 static DEVICE_ATTR_RW(disksize
);
1062 static DEVICE_ATTR_RO(initstate
);
1063 static DEVICE_ATTR_WO(reset
);
1064 static DEVICE_ATTR_RO(orig_data_size
);
1065 static DEVICE_ATTR_RO(mem_used_total
);
1066 static DEVICE_ATTR_RW(mem_limit
);
1067 static DEVICE_ATTR_RW(mem_used_max
);
1068 static DEVICE_ATTR_RW(max_comp_streams
);
1069 static DEVICE_ATTR_RW(comp_algorithm
);
1071 static ssize_t
io_stat_show(struct device
*dev
,
1072 struct device_attribute
*attr
, char *buf
)
1074 struct zram
*zram
= dev_to_zram(dev
);
1077 down_read(&zram
->init_lock
);
1078 ret
= scnprintf(buf
, PAGE_SIZE
,
1079 "%8llu %8llu %8llu %8llu\n",
1080 (u64
)atomic64_read(&zram
->stats
.failed_reads
),
1081 (u64
)atomic64_read(&zram
->stats
.failed_writes
),
1082 (u64
)atomic64_read(&zram
->stats
.invalid_io
),
1083 (u64
)atomic64_read(&zram
->stats
.notify_free
));
1084 up_read(&zram
->init_lock
);
1089 static ssize_t
mm_stat_show(struct device
*dev
,
1090 struct device_attribute
*attr
, char *buf
)
1092 struct zram
*zram
= dev_to_zram(dev
);
1093 u64 orig_size
, mem_used
= 0;
1097 down_read(&zram
->init_lock
);
1098 if (init_done(zram
))
1099 mem_used
= zs_get_total_pages(zram
->meta
->mem_pool
);
1101 orig_size
= atomic64_read(&zram
->stats
.pages_stored
);
1102 max_used
= atomic_long_read(&zram
->stats
.max_used_pages
);
1104 ret
= scnprintf(buf
, PAGE_SIZE
,
1105 "%8llu %8llu %8llu %8lu %8ld %8llu %8llu\n",
1106 orig_size
<< PAGE_SHIFT
,
1107 (u64
)atomic64_read(&zram
->stats
.compr_data_size
),
1108 mem_used
<< PAGE_SHIFT
,
1109 zram
->limit_pages
<< PAGE_SHIFT
,
1110 max_used
<< PAGE_SHIFT
,
1111 (u64
)atomic64_read(&zram
->stats
.zero_pages
),
1112 (u64
)atomic64_read(&zram
->stats
.num_migrated
));
1113 up_read(&zram
->init_lock
);
1118 static DEVICE_ATTR_RO(io_stat
);
1119 static DEVICE_ATTR_RO(mm_stat
);
1120 ZRAM_ATTR_RO(num_reads
);
1121 ZRAM_ATTR_RO(num_writes
);
1122 ZRAM_ATTR_RO(failed_reads
);
1123 ZRAM_ATTR_RO(failed_writes
);
1124 ZRAM_ATTR_RO(invalid_io
);
1125 ZRAM_ATTR_RO(notify_free
);
1126 ZRAM_ATTR_RO(zero_pages
);
1127 ZRAM_ATTR_RO(compr_data_size
);
1129 static struct attribute
*zram_disk_attrs
[] = {
1130 &dev_attr_disksize
.attr
,
1131 &dev_attr_initstate
.attr
,
1132 &dev_attr_reset
.attr
,
1133 &dev_attr_num_reads
.attr
,
1134 &dev_attr_num_writes
.attr
,
1135 &dev_attr_failed_reads
.attr
,
1136 &dev_attr_failed_writes
.attr
,
1137 &dev_attr_compact
.attr
,
1138 &dev_attr_invalid_io
.attr
,
1139 &dev_attr_notify_free
.attr
,
1140 &dev_attr_zero_pages
.attr
,
1141 &dev_attr_orig_data_size
.attr
,
1142 &dev_attr_compr_data_size
.attr
,
1143 &dev_attr_mem_used_total
.attr
,
1144 &dev_attr_mem_limit
.attr
,
1145 &dev_attr_mem_used_max
.attr
,
1146 &dev_attr_max_comp_streams
.attr
,
1147 &dev_attr_comp_algorithm
.attr
,
1148 &dev_attr_io_stat
.attr
,
1149 &dev_attr_mm_stat
.attr
,
1153 static struct attribute_group zram_disk_attr_group
= {
1154 .attrs
= zram_disk_attrs
,
1157 static int create_device(struct zram
*zram
, int device_id
)
1159 struct request_queue
*queue
;
1162 init_rwsem(&zram
->init_lock
);
1164 queue
= blk_alloc_queue(GFP_KERNEL
);
1166 pr_err("Error allocating disk queue for device %d\n",
1171 blk_queue_make_request(queue
, zram_make_request
);
1173 /* gendisk structure */
1174 zram
->disk
= alloc_disk(1);
1176 pr_warn("Error allocating disk structure for device %d\n",
1179 goto out_free_queue
;
1182 zram
->disk
->major
= zram_major
;
1183 zram
->disk
->first_minor
= device_id
;
1184 zram
->disk
->fops
= &zram_devops
;
1185 zram
->disk
->queue
= queue
;
1186 zram
->disk
->queue
->queuedata
= zram
;
1187 zram
->disk
->private_data
= zram
;
1188 snprintf(zram
->disk
->disk_name
, 16, "zram%d", device_id
);
1190 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1191 set_capacity(zram
->disk
, 0);
1192 /* zram devices sort of resembles non-rotational disks */
1193 queue_flag_set_unlocked(QUEUE_FLAG_NONROT
, zram
->disk
->queue
);
1194 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM
, zram
->disk
->queue
);
1196 * To ensure that we always get PAGE_SIZE aligned
1197 * and n*PAGE_SIZED sized I/O requests.
1199 blk_queue_physical_block_size(zram
->disk
->queue
, PAGE_SIZE
);
1200 blk_queue_logical_block_size(zram
->disk
->queue
,
1201 ZRAM_LOGICAL_BLOCK_SIZE
);
1202 blk_queue_io_min(zram
->disk
->queue
, PAGE_SIZE
);
1203 blk_queue_io_opt(zram
->disk
->queue
, PAGE_SIZE
);
1204 zram
->disk
->queue
->limits
.discard_granularity
= PAGE_SIZE
;
1205 zram
->disk
->queue
->limits
.max_discard_sectors
= UINT_MAX
;
1207 * zram_bio_discard() will clear all logical blocks if logical block
1208 * size is identical with physical block size(PAGE_SIZE). But if it is
1209 * different, we will skip discarding some parts of logical blocks in
1210 * the part of the request range which isn't aligned to physical block
1211 * size. So we can't ensure that all discarded logical blocks are
1214 if (ZRAM_LOGICAL_BLOCK_SIZE
== PAGE_SIZE
)
1215 zram
->disk
->queue
->limits
.discard_zeroes_data
= 1;
1217 zram
->disk
->queue
->limits
.discard_zeroes_data
= 0;
1218 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD
, zram
->disk
->queue
);
1220 add_disk(zram
->disk
);
1222 ret
= sysfs_create_group(&disk_to_dev(zram
->disk
)->kobj
,
1223 &zram_disk_attr_group
);
1225 pr_warn("Error creating sysfs group");
1228 strlcpy(zram
->compressor
, default_compressor
, sizeof(zram
->compressor
));
1230 zram
->max_comp_streams
= 1;
1234 del_gendisk(zram
->disk
);
1235 put_disk(zram
->disk
);
1237 blk_cleanup_queue(queue
);
1242 static void destroy_devices(unsigned int nr
)
1247 for (i
= 0; i
< nr
; i
++) {
1248 zram
= &zram_devices
[i
];
1250 * Remove sysfs first, so no one will perform a disksize
1251 * store while we destroy the devices
1253 sysfs_remove_group(&disk_to_dev(zram
->disk
)->kobj
,
1254 &zram_disk_attr_group
);
1256 zram_reset_device(zram
);
1258 blk_cleanup_queue(zram
->disk
->queue
);
1259 del_gendisk(zram
->disk
);
1260 put_disk(zram
->disk
);
1263 kfree(zram_devices
);
1264 unregister_blkdev(zram_major
, "zram");
1265 pr_info("Destroyed %u device(s)\n", nr
);
1268 static int __init
zram_init(void)
1272 if (num_devices
> max_num_devices
) {
1273 pr_warn("Invalid value for num_devices: %u\n",
1278 zram_major
= register_blkdev(0, "zram");
1279 if (zram_major
<= 0) {
1280 pr_warn("Unable to get major number\n");
1284 /* Allocate the device array and initialize each one */
1285 zram_devices
= kzalloc(num_devices
* sizeof(struct zram
), GFP_KERNEL
);
1286 if (!zram_devices
) {
1287 unregister_blkdev(zram_major
, "zram");
1291 for (dev_id
= 0; dev_id
< num_devices
; dev_id
++) {
1292 ret
= create_device(&zram_devices
[dev_id
], dev_id
);
1297 pr_info("Created %u device(s)\n", num_devices
);
1301 destroy_devices(dev_id
);
1305 static void __exit
zram_exit(void)
1307 destroy_devices(num_devices
);
1310 module_init(zram_init
);
1311 module_exit(zram_exit
);
1313 module_param(num_devices
, uint
, 0);
1314 MODULE_PARM_DESC(num_devices
, "Number of zram devices");
1316 MODULE_LICENSE("Dual BSD/GPL");
1317 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1318 MODULE_DESCRIPTION("Compressed RAM Block Device");