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 #ifdef CONFIG_ZRAM_DEBUG
22 #include <linux/module.h>
23 #include <linux/kernel.h>
24 #include <linux/bio.h>
25 #include <linux/bitops.h>
26 #include <linux/blkdev.h>
27 #include <linux/buffer_head.h>
28 #include <linux/device.h>
29 #include <linux/genhd.h>
30 #include <linux/highmem.h>
31 #include <linux/slab.h>
32 #include <linux/string.h>
33 #include <linux/vmalloc.h>
34 #include <linux/err.h>
39 static int zram_major
;
40 static struct zram
*zram_devices
;
41 static const char *default_compressor
= "lzo";
43 /* Module params (documentation at end) */
44 static unsigned int num_devices
= 1;
46 #define ZRAM_ATTR_RO(name) \
47 static ssize_t zram_attr_##name##_show(struct device *d, \
48 struct device_attribute *attr, char *b) \
50 struct zram *zram = dev_to_zram(d); \
51 return scnprintf(b, PAGE_SIZE, "%llu\n", \
52 (u64)atomic64_read(&zram->stats.name)); \
54 static struct device_attribute dev_attr_##name = \
55 __ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL);
57 static inline int init_done(struct zram
*zram
)
59 return zram
->meta
!= NULL
;
62 static inline struct zram
*dev_to_zram(struct device
*dev
)
64 return (struct zram
*)dev_to_disk(dev
)->private_data
;
67 static ssize_t
disksize_show(struct device
*dev
,
68 struct device_attribute
*attr
, char *buf
)
70 struct zram
*zram
= dev_to_zram(dev
);
72 return scnprintf(buf
, PAGE_SIZE
, "%llu\n", zram
->disksize
);
75 static ssize_t
initstate_show(struct device
*dev
,
76 struct device_attribute
*attr
, char *buf
)
79 struct zram
*zram
= dev_to_zram(dev
);
81 down_read(&zram
->init_lock
);
82 val
= init_done(zram
);
83 up_read(&zram
->init_lock
);
85 return scnprintf(buf
, PAGE_SIZE
, "%u\n", val
);
88 static ssize_t
orig_data_size_show(struct device
*dev
,
89 struct device_attribute
*attr
, char *buf
)
91 struct zram
*zram
= dev_to_zram(dev
);
93 return scnprintf(buf
, PAGE_SIZE
, "%llu\n",
94 (u64
)(atomic64_read(&zram
->stats
.pages_stored
)) << PAGE_SHIFT
);
97 static ssize_t
mem_used_total_show(struct device
*dev
,
98 struct device_attribute
*attr
, char *buf
)
101 struct zram
*zram
= dev_to_zram(dev
);
102 struct zram_meta
*meta
= zram
->meta
;
104 down_read(&zram
->init_lock
);
106 val
= zs_get_total_size_bytes(meta
->mem_pool
);
107 up_read(&zram
->init_lock
);
109 return scnprintf(buf
, PAGE_SIZE
, "%llu\n", val
);
112 static ssize_t
max_comp_streams_show(struct device
*dev
,
113 struct device_attribute
*attr
, char *buf
)
116 struct zram
*zram
= dev_to_zram(dev
);
118 down_read(&zram
->init_lock
);
119 val
= zram
->max_comp_streams
;
120 up_read(&zram
->init_lock
);
122 return scnprintf(buf
, PAGE_SIZE
, "%d\n", val
);
125 static ssize_t
max_comp_streams_store(struct device
*dev
,
126 struct device_attribute
*attr
, const char *buf
, size_t len
)
129 struct zram
*zram
= dev_to_zram(dev
);
132 ret
= kstrtoint(buf
, 0, &num
);
138 down_write(&zram
->init_lock
);
139 if (init_done(zram
)) {
140 if (!zcomp_set_max_streams(zram
->comp
, num
)) {
141 pr_info("Cannot change max compression streams\n");
147 zram
->max_comp_streams
= num
;
150 up_write(&zram
->init_lock
);
154 static ssize_t
comp_algorithm_show(struct device
*dev
,
155 struct device_attribute
*attr
, char *buf
)
158 struct zram
*zram
= dev_to_zram(dev
);
160 down_read(&zram
->init_lock
);
161 sz
= zcomp_available_show(zram
->compressor
, buf
);
162 up_read(&zram
->init_lock
);
167 static ssize_t
comp_algorithm_store(struct device
*dev
,
168 struct device_attribute
*attr
, const char *buf
, size_t len
)
170 struct zram
*zram
= dev_to_zram(dev
);
171 down_write(&zram
->init_lock
);
172 if (init_done(zram
)) {
173 up_write(&zram
->init_lock
);
174 pr_info("Can't change algorithm for initialized device\n");
177 strlcpy(zram
->compressor
, buf
, sizeof(zram
->compressor
));
178 up_write(&zram
->init_lock
);
182 /* flag operations needs meta->tb_lock */
183 static int zram_test_flag(struct zram_meta
*meta
, u32 index
,
184 enum zram_pageflags flag
)
186 return meta
->table
[index
].flags
& BIT(flag
);
189 static void zram_set_flag(struct zram_meta
*meta
, u32 index
,
190 enum zram_pageflags flag
)
192 meta
->table
[index
].flags
|= BIT(flag
);
195 static void zram_clear_flag(struct zram_meta
*meta
, u32 index
,
196 enum zram_pageflags flag
)
198 meta
->table
[index
].flags
&= ~BIT(flag
);
201 static inline int is_partial_io(struct bio_vec
*bvec
)
203 return bvec
->bv_len
!= PAGE_SIZE
;
207 * Check if request is within bounds and aligned on zram logical blocks.
209 static inline int valid_io_request(struct zram
*zram
, struct bio
*bio
)
211 u64 start
, end
, bound
;
213 /* unaligned request */
214 if (unlikely(bio
->bi_iter
.bi_sector
&
215 (ZRAM_SECTOR_PER_LOGICAL_BLOCK
- 1)))
217 if (unlikely(bio
->bi_iter
.bi_size
& (ZRAM_LOGICAL_BLOCK_SIZE
- 1)))
220 start
= bio
->bi_iter
.bi_sector
;
221 end
= start
+ (bio
->bi_iter
.bi_size
>> SECTOR_SHIFT
);
222 bound
= zram
->disksize
>> SECTOR_SHIFT
;
223 /* out of range range */
224 if (unlikely(start
>= bound
|| end
> bound
|| start
> end
))
227 /* I/O request is valid */
231 static void zram_meta_free(struct zram_meta
*meta
)
233 zs_destroy_pool(meta
->mem_pool
);
238 static struct zram_meta
*zram_meta_alloc(u64 disksize
)
241 struct zram_meta
*meta
= kmalloc(sizeof(*meta
), GFP_KERNEL
);
245 num_pages
= disksize
>> PAGE_SHIFT
;
246 meta
->table
= vzalloc(num_pages
* sizeof(*meta
->table
));
248 pr_err("Error allocating zram address table\n");
252 meta
->mem_pool
= zs_create_pool(GFP_NOIO
| __GFP_HIGHMEM
);
253 if (!meta
->mem_pool
) {
254 pr_err("Error creating memory pool\n");
258 rwlock_init(&meta
->tb_lock
);
270 static void update_position(u32
*index
, int *offset
, struct bio_vec
*bvec
)
272 if (*offset
+ bvec
->bv_len
>= PAGE_SIZE
)
274 *offset
= (*offset
+ bvec
->bv_len
) % PAGE_SIZE
;
277 static int page_zero_filled(void *ptr
)
282 page
= (unsigned long *)ptr
;
284 for (pos
= 0; pos
!= PAGE_SIZE
/ sizeof(*page
); pos
++) {
292 static void handle_zero_page(struct bio_vec
*bvec
)
294 struct page
*page
= bvec
->bv_page
;
297 user_mem
= kmap_atomic(page
);
298 if (is_partial_io(bvec
))
299 memset(user_mem
+ bvec
->bv_offset
, 0, bvec
->bv_len
);
301 clear_page(user_mem
);
302 kunmap_atomic(user_mem
);
304 flush_dcache_page(page
);
307 /* NOTE: caller should hold meta->tb_lock with write-side */
308 static void zram_free_page(struct zram
*zram
, size_t index
)
310 struct zram_meta
*meta
= zram
->meta
;
311 unsigned long handle
= meta
->table
[index
].handle
;
313 if (unlikely(!handle
)) {
315 * No memory is allocated for zero filled pages.
316 * Simply clear zero page flag.
318 if (zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
319 zram_clear_flag(meta
, index
, ZRAM_ZERO
);
320 atomic64_dec(&zram
->stats
.zero_pages
);
325 zs_free(meta
->mem_pool
, handle
);
327 atomic64_sub(meta
->table
[index
].size
, &zram
->stats
.compr_data_size
);
328 atomic64_dec(&zram
->stats
.pages_stored
);
330 meta
->table
[index
].handle
= 0;
331 meta
->table
[index
].size
= 0;
334 static int zram_decompress_page(struct zram
*zram
, char *mem
, u32 index
)
338 struct zram_meta
*meta
= zram
->meta
;
339 unsigned long handle
;
342 read_lock(&meta
->tb_lock
);
343 handle
= meta
->table
[index
].handle
;
344 size
= meta
->table
[index
].size
;
346 if (!handle
|| zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
347 read_unlock(&meta
->tb_lock
);
352 cmem
= zs_map_object(meta
->mem_pool
, handle
, ZS_MM_RO
);
353 if (size
== PAGE_SIZE
)
354 copy_page(mem
, cmem
);
356 ret
= zcomp_decompress(zram
->comp
, cmem
, size
, mem
);
357 zs_unmap_object(meta
->mem_pool
, handle
);
358 read_unlock(&meta
->tb_lock
);
360 /* Should NEVER happen. Return bio error if it does. */
362 pr_err("Decompression failed! err=%d, page=%u\n", ret
, index
);
363 atomic64_inc(&zram
->stats
.failed_reads
);
370 static int zram_bvec_read(struct zram
*zram
, struct bio_vec
*bvec
,
371 u32 index
, int offset
, struct bio
*bio
)
375 unsigned char *user_mem
, *uncmem
= NULL
;
376 struct zram_meta
*meta
= zram
->meta
;
377 page
= bvec
->bv_page
;
379 read_lock(&meta
->tb_lock
);
380 if (unlikely(!meta
->table
[index
].handle
) ||
381 zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
382 read_unlock(&meta
->tb_lock
);
383 handle_zero_page(bvec
);
386 read_unlock(&meta
->tb_lock
);
388 if (is_partial_io(bvec
))
389 /* Use a temporary buffer to decompress the page */
390 uncmem
= kmalloc(PAGE_SIZE
, GFP_NOIO
);
392 user_mem
= kmap_atomic(page
);
393 if (!is_partial_io(bvec
))
397 pr_info("Unable to allocate temp memory\n");
402 ret
= zram_decompress_page(zram
, uncmem
, index
);
403 /* Should NEVER happen. Return bio error if it does. */
407 if (is_partial_io(bvec
))
408 memcpy(user_mem
+ bvec
->bv_offset
, uncmem
+ offset
,
411 flush_dcache_page(page
);
414 kunmap_atomic(user_mem
);
415 if (is_partial_io(bvec
))
420 static int zram_bvec_write(struct zram
*zram
, struct bio_vec
*bvec
, u32 index
,
425 unsigned long handle
;
427 unsigned char *user_mem
, *cmem
, *src
, *uncmem
= NULL
;
428 struct zram_meta
*meta
= zram
->meta
;
429 struct zcomp_strm
*zstrm
;
432 page
= bvec
->bv_page
;
433 if (is_partial_io(bvec
)) {
435 * This is a partial IO. We need to read the full page
436 * before to write the changes.
438 uncmem
= kmalloc(PAGE_SIZE
, GFP_NOIO
);
443 ret
= zram_decompress_page(zram
, uncmem
, index
);
448 zstrm
= zcomp_strm_find(zram
->comp
);
450 user_mem
= kmap_atomic(page
);
452 if (is_partial_io(bvec
)) {
453 memcpy(uncmem
+ offset
, user_mem
+ bvec
->bv_offset
,
455 kunmap_atomic(user_mem
);
461 if (page_zero_filled(uncmem
)) {
462 kunmap_atomic(user_mem
);
463 /* Free memory associated with this sector now. */
464 write_lock(&zram
->meta
->tb_lock
);
465 zram_free_page(zram
, index
);
466 zram_set_flag(meta
, index
, ZRAM_ZERO
);
467 write_unlock(&zram
->meta
->tb_lock
);
469 atomic64_inc(&zram
->stats
.zero_pages
);
474 ret
= zcomp_compress(zram
->comp
, zstrm
, uncmem
, &clen
);
475 if (!is_partial_io(bvec
)) {
476 kunmap_atomic(user_mem
);
482 pr_err("Compression failed! err=%d\n", ret
);
486 if (unlikely(clen
> max_zpage_size
)) {
488 if (is_partial_io(bvec
))
492 handle
= zs_malloc(meta
->mem_pool
, clen
);
494 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
499 cmem
= zs_map_object(meta
->mem_pool
, handle
, ZS_MM_WO
);
501 if ((clen
== PAGE_SIZE
) && !is_partial_io(bvec
)) {
502 src
= kmap_atomic(page
);
503 copy_page(cmem
, src
);
506 memcpy(cmem
, src
, clen
);
509 zcomp_strm_release(zram
->comp
, zstrm
);
511 zs_unmap_object(meta
->mem_pool
, handle
);
514 * Free memory associated with this sector
515 * before overwriting unused sectors.
517 write_lock(&zram
->meta
->tb_lock
);
518 zram_free_page(zram
, index
);
520 meta
->table
[index
].handle
= handle
;
521 meta
->table
[index
].size
= clen
;
522 write_unlock(&zram
->meta
->tb_lock
);
525 atomic64_add(clen
, &zram
->stats
.compr_data_size
);
526 atomic64_inc(&zram
->stats
.pages_stored
);
529 zcomp_strm_release(zram
->comp
, zstrm
);
530 if (is_partial_io(bvec
))
533 atomic64_inc(&zram
->stats
.failed_writes
);
537 static int zram_bvec_rw(struct zram
*zram
, struct bio_vec
*bvec
, u32 index
,
538 int offset
, struct bio
*bio
)
541 int rw
= bio_data_dir(bio
);
544 atomic64_inc(&zram
->stats
.num_reads
);
545 ret
= zram_bvec_read(zram
, bvec
, index
, offset
, bio
);
547 atomic64_inc(&zram
->stats
.num_writes
);
548 ret
= zram_bvec_write(zram
, bvec
, index
, offset
);
555 * zram_bio_discard - handler on discard request
556 * @index: physical block index in PAGE_SIZE units
557 * @offset: byte offset within physical block
559 static void zram_bio_discard(struct zram
*zram
, u32 index
,
560 int offset
, struct bio
*bio
)
562 size_t n
= bio
->bi_iter
.bi_size
;
565 * zram manages data in physical block size units. Because logical block
566 * size isn't identical with physical block size on some arch, we
567 * could get a discard request pointing to a specific offset within a
568 * certain physical block. Although we can handle this request by
569 * reading that physiclal block and decompressing and partially zeroing
570 * and re-compressing and then re-storing it, this isn't reasonable
571 * because our intent with a discard request is to save memory. So
572 * skipping this logical block is appropriate here.
575 if (n
<= (PAGE_SIZE
- offset
))
578 n
-= (PAGE_SIZE
- offset
);
582 while (n
>= PAGE_SIZE
) {
584 * Discard request can be large so the lock hold times could be
585 * lengthy. So take the lock once per page.
587 write_lock(&zram
->meta
->tb_lock
);
588 zram_free_page(zram
, index
);
589 write_unlock(&zram
->meta
->tb_lock
);
595 static void zram_reset_device(struct zram
*zram
, bool reset_capacity
)
598 struct zram_meta
*meta
;
600 down_write(&zram
->init_lock
);
601 if (!init_done(zram
)) {
602 up_write(&zram
->init_lock
);
607 /* Free all pages that are still in this zram device */
608 for (index
= 0; index
< zram
->disksize
>> PAGE_SHIFT
; index
++) {
609 unsigned long handle
= meta
->table
[index
].handle
;
613 zs_free(meta
->mem_pool
, handle
);
616 zcomp_destroy(zram
->comp
);
617 zram
->max_comp_streams
= 1;
619 zram_meta_free(zram
->meta
);
622 memset(&zram
->stats
, 0, sizeof(zram
->stats
));
626 set_capacity(zram
->disk
, 0);
628 up_write(&zram
->init_lock
);
631 * Revalidate disk out of the init_lock to avoid lockdep splat.
632 * It's okay because disk's capacity is protected by init_lock
633 * so that revalidate_disk always sees up-to-date capacity.
636 revalidate_disk(zram
->disk
);
639 static ssize_t
disksize_store(struct device
*dev
,
640 struct device_attribute
*attr
, const char *buf
, size_t len
)
644 struct zram_meta
*meta
;
645 struct zram
*zram
= dev_to_zram(dev
);
648 disksize
= memparse(buf
, NULL
);
652 disksize
= PAGE_ALIGN(disksize
);
653 meta
= zram_meta_alloc(disksize
);
657 comp
= zcomp_create(zram
->compressor
, zram
->max_comp_streams
);
659 pr_info("Cannot initialise %s compressing backend\n",
665 down_write(&zram
->init_lock
);
666 if (init_done(zram
)) {
667 pr_info("Cannot change disksize for initialized device\n");
669 goto out_destroy_comp
;
674 zram
->disksize
= disksize
;
675 set_capacity(zram
->disk
, zram
->disksize
>> SECTOR_SHIFT
);
676 up_write(&zram
->init_lock
);
679 * Revalidate disk out of the init_lock to avoid lockdep splat.
680 * It's okay because disk's capacity is protected by init_lock
681 * so that revalidate_disk always sees up-to-date capacity.
683 revalidate_disk(zram
->disk
);
688 up_write(&zram
->init_lock
);
691 zram_meta_free(meta
);
695 static ssize_t
reset_store(struct device
*dev
,
696 struct device_attribute
*attr
, const char *buf
, size_t len
)
699 unsigned short do_reset
;
701 struct block_device
*bdev
;
703 zram
= dev_to_zram(dev
);
704 bdev
= bdget_disk(zram
->disk
, 0);
709 /* Do not reset an active device! */
710 if (bdev
->bd_holders
) {
715 ret
= kstrtou16(buf
, 10, &do_reset
);
724 /* Make sure all pending I/O is finished */
728 zram_reset_device(zram
, true);
736 static void __zram_make_request(struct zram
*zram
, struct bio
*bio
)
741 struct bvec_iter iter
;
743 index
= bio
->bi_iter
.bi_sector
>> SECTORS_PER_PAGE_SHIFT
;
744 offset
= (bio
->bi_iter
.bi_sector
&
745 (SECTORS_PER_PAGE
- 1)) << SECTOR_SHIFT
;
747 if (unlikely(bio
->bi_rw
& REQ_DISCARD
)) {
748 zram_bio_discard(zram
, index
, offset
, bio
);
753 bio_for_each_segment(bvec
, bio
, iter
) {
754 int max_transfer_size
= PAGE_SIZE
- offset
;
756 if (bvec
.bv_len
> max_transfer_size
) {
758 * zram_bvec_rw() can only make operation on a single
759 * zram page. Split the bio vector.
763 bv
.bv_page
= bvec
.bv_page
;
764 bv
.bv_len
= max_transfer_size
;
765 bv
.bv_offset
= bvec
.bv_offset
;
767 if (zram_bvec_rw(zram
, &bv
, index
, offset
, bio
) < 0)
770 bv
.bv_len
= bvec
.bv_len
- max_transfer_size
;
771 bv
.bv_offset
+= max_transfer_size
;
772 if (zram_bvec_rw(zram
, &bv
, index
+ 1, 0, bio
) < 0)
775 if (zram_bvec_rw(zram
, &bvec
, index
, offset
, bio
) < 0)
778 update_position(&index
, &offset
, &bvec
);
781 set_bit(BIO_UPTODATE
, &bio
->bi_flags
);
790 * Handler function for all zram I/O requests.
792 static void zram_make_request(struct request_queue
*queue
, struct bio
*bio
)
794 struct zram
*zram
= queue
->queuedata
;
796 down_read(&zram
->init_lock
);
797 if (unlikely(!init_done(zram
)))
800 if (!valid_io_request(zram
, bio
)) {
801 atomic64_inc(&zram
->stats
.invalid_io
);
805 __zram_make_request(zram
, bio
);
806 up_read(&zram
->init_lock
);
811 up_read(&zram
->init_lock
);
815 static void zram_slot_free_notify(struct block_device
*bdev
,
819 struct zram_meta
*meta
;
821 zram
= bdev
->bd_disk
->private_data
;
824 write_lock(&meta
->tb_lock
);
825 zram_free_page(zram
, index
);
826 write_unlock(&meta
->tb_lock
);
827 atomic64_inc(&zram
->stats
.notify_free
);
830 static const struct block_device_operations zram_devops
= {
831 .swap_slot_free_notify
= zram_slot_free_notify
,
835 static DEVICE_ATTR(disksize
, S_IRUGO
| S_IWUSR
,
836 disksize_show
, disksize_store
);
837 static DEVICE_ATTR(initstate
, S_IRUGO
, initstate_show
, NULL
);
838 static DEVICE_ATTR(reset
, S_IWUSR
, NULL
, reset_store
);
839 static DEVICE_ATTR(orig_data_size
, S_IRUGO
, orig_data_size_show
, NULL
);
840 static DEVICE_ATTR(mem_used_total
, S_IRUGO
, mem_used_total_show
, NULL
);
841 static DEVICE_ATTR(max_comp_streams
, S_IRUGO
| S_IWUSR
,
842 max_comp_streams_show
, max_comp_streams_store
);
843 static DEVICE_ATTR(comp_algorithm
, S_IRUGO
| S_IWUSR
,
844 comp_algorithm_show
, comp_algorithm_store
);
846 ZRAM_ATTR_RO(num_reads
);
847 ZRAM_ATTR_RO(num_writes
);
848 ZRAM_ATTR_RO(failed_reads
);
849 ZRAM_ATTR_RO(failed_writes
);
850 ZRAM_ATTR_RO(invalid_io
);
851 ZRAM_ATTR_RO(notify_free
);
852 ZRAM_ATTR_RO(zero_pages
);
853 ZRAM_ATTR_RO(compr_data_size
);
855 static struct attribute
*zram_disk_attrs
[] = {
856 &dev_attr_disksize
.attr
,
857 &dev_attr_initstate
.attr
,
858 &dev_attr_reset
.attr
,
859 &dev_attr_num_reads
.attr
,
860 &dev_attr_num_writes
.attr
,
861 &dev_attr_failed_reads
.attr
,
862 &dev_attr_failed_writes
.attr
,
863 &dev_attr_invalid_io
.attr
,
864 &dev_attr_notify_free
.attr
,
865 &dev_attr_zero_pages
.attr
,
866 &dev_attr_orig_data_size
.attr
,
867 &dev_attr_compr_data_size
.attr
,
868 &dev_attr_mem_used_total
.attr
,
869 &dev_attr_max_comp_streams
.attr
,
870 &dev_attr_comp_algorithm
.attr
,
874 static struct attribute_group zram_disk_attr_group
= {
875 .attrs
= zram_disk_attrs
,
878 static int create_device(struct zram
*zram
, int device_id
)
882 init_rwsem(&zram
->init_lock
);
884 zram
->queue
= blk_alloc_queue(GFP_KERNEL
);
886 pr_err("Error allocating disk queue for device %d\n",
891 blk_queue_make_request(zram
->queue
, zram_make_request
);
892 zram
->queue
->queuedata
= zram
;
894 /* gendisk structure */
895 zram
->disk
= alloc_disk(1);
897 pr_warn("Error allocating disk structure for device %d\n",
902 zram
->disk
->major
= zram_major
;
903 zram
->disk
->first_minor
= device_id
;
904 zram
->disk
->fops
= &zram_devops
;
905 zram
->disk
->queue
= zram
->queue
;
906 zram
->disk
->private_data
= zram
;
907 snprintf(zram
->disk
->disk_name
, 16, "zram%d", device_id
);
909 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
910 set_capacity(zram
->disk
, 0);
911 /* zram devices sort of resembles non-rotational disks */
912 queue_flag_set_unlocked(QUEUE_FLAG_NONROT
, zram
->disk
->queue
);
914 * To ensure that we always get PAGE_SIZE aligned
915 * and n*PAGE_SIZED sized I/O requests.
917 blk_queue_physical_block_size(zram
->disk
->queue
, PAGE_SIZE
);
918 blk_queue_logical_block_size(zram
->disk
->queue
,
919 ZRAM_LOGICAL_BLOCK_SIZE
);
920 blk_queue_io_min(zram
->disk
->queue
, PAGE_SIZE
);
921 blk_queue_io_opt(zram
->disk
->queue
, PAGE_SIZE
);
922 zram
->disk
->queue
->limits
.discard_granularity
= PAGE_SIZE
;
923 zram
->disk
->queue
->limits
.max_discard_sectors
= UINT_MAX
;
925 * zram_bio_discard() will clear all logical blocks if logical block
926 * size is identical with physical block size(PAGE_SIZE). But if it is
927 * different, we will skip discarding some parts of logical blocks in
928 * the part of the request range which isn't aligned to physical block
929 * size. So we can't ensure that all discarded logical blocks are
932 if (ZRAM_LOGICAL_BLOCK_SIZE
== PAGE_SIZE
)
933 zram
->disk
->queue
->limits
.discard_zeroes_data
= 1;
935 zram
->disk
->queue
->limits
.discard_zeroes_data
= 0;
936 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD
, zram
->disk
->queue
);
938 add_disk(zram
->disk
);
940 ret
= sysfs_create_group(&disk_to_dev(zram
->disk
)->kobj
,
941 &zram_disk_attr_group
);
943 pr_warn("Error creating sysfs group");
946 strlcpy(zram
->compressor
, default_compressor
, sizeof(zram
->compressor
));
948 zram
->max_comp_streams
= 1;
952 del_gendisk(zram
->disk
);
953 put_disk(zram
->disk
);
955 blk_cleanup_queue(zram
->queue
);
960 static void destroy_device(struct zram
*zram
)
962 sysfs_remove_group(&disk_to_dev(zram
->disk
)->kobj
,
963 &zram_disk_attr_group
);
965 del_gendisk(zram
->disk
);
966 put_disk(zram
->disk
);
968 blk_cleanup_queue(zram
->queue
);
971 static int __init
zram_init(void)
975 if (num_devices
> max_num_devices
) {
976 pr_warn("Invalid value for num_devices: %u\n",
982 zram_major
= register_blkdev(0, "zram");
983 if (zram_major
<= 0) {
984 pr_warn("Unable to get major number\n");
989 /* Allocate the device array and initialize each one */
990 zram_devices
= kzalloc(num_devices
* sizeof(struct zram
), GFP_KERNEL
);
996 for (dev_id
= 0; dev_id
< num_devices
; dev_id
++) {
997 ret
= create_device(&zram_devices
[dev_id
], dev_id
);
1002 pr_info("Created %u device(s) ...\n", num_devices
);
1008 destroy_device(&zram_devices
[--dev_id
]);
1009 kfree(zram_devices
);
1011 unregister_blkdev(zram_major
, "zram");
1016 static void __exit
zram_exit(void)
1021 for (i
= 0; i
< num_devices
; i
++) {
1022 zram
= &zram_devices
[i
];
1024 destroy_device(zram
);
1026 * Shouldn't access zram->disk after destroy_device
1027 * because destroy_device already released zram->disk.
1029 zram_reset_device(zram
, false);
1032 unregister_blkdev(zram_major
, "zram");
1034 kfree(zram_devices
);
1035 pr_debug("Cleanup done!\n");
1038 module_init(zram_init
);
1039 module_exit(zram_exit
);
1041 module_param(num_devices
, uint
, 0);
1042 MODULE_PARM_DESC(num_devices
, "Number of zram devices");
1044 MODULE_LICENSE("Dual BSD/GPL");
1045 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1046 MODULE_DESCRIPTION("Compressed RAM Block Device");