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/lzo.h>
33 #include <linux/string.h>
34 #include <linux/vmalloc.h>
39 static int zram_major
;
40 static struct zram
*zram_devices
;
42 /* Module params (documentation at end) */
43 static unsigned int num_devices
= 1;
45 static inline struct zram
*dev_to_zram(struct device
*dev
)
47 return (struct zram
*)dev_to_disk(dev
)->private_data
;
50 static ssize_t
disksize_show(struct device
*dev
,
51 struct device_attribute
*attr
, char *buf
)
53 struct zram
*zram
= dev_to_zram(dev
);
55 return sprintf(buf
, "%llu\n", zram
->disksize
);
58 static ssize_t
initstate_show(struct device
*dev
,
59 struct device_attribute
*attr
, char *buf
)
61 struct zram
*zram
= dev_to_zram(dev
);
63 return sprintf(buf
, "%u\n", zram
->init_done
);
66 static ssize_t
num_reads_show(struct device
*dev
,
67 struct device_attribute
*attr
, char *buf
)
69 struct zram
*zram
= dev_to_zram(dev
);
71 return sprintf(buf
, "%llu\n",
72 (u64
)atomic64_read(&zram
->stats
.num_reads
));
75 static ssize_t
num_writes_show(struct device
*dev
,
76 struct device_attribute
*attr
, char *buf
)
78 struct zram
*zram
= dev_to_zram(dev
);
80 return sprintf(buf
, "%llu\n",
81 (u64
)atomic64_read(&zram
->stats
.num_writes
));
84 static ssize_t
invalid_io_show(struct device
*dev
,
85 struct device_attribute
*attr
, char *buf
)
87 struct zram
*zram
= dev_to_zram(dev
);
89 return sprintf(buf
, "%llu\n",
90 (u64
)atomic64_read(&zram
->stats
.invalid_io
));
93 static ssize_t
notify_free_show(struct device
*dev
,
94 struct device_attribute
*attr
, char *buf
)
96 struct zram
*zram
= dev_to_zram(dev
);
98 return sprintf(buf
, "%llu\n",
99 (u64
)atomic64_read(&zram
->stats
.notify_free
));
102 static ssize_t
zero_pages_show(struct device
*dev
,
103 struct device_attribute
*attr
, char *buf
)
105 struct zram
*zram
= dev_to_zram(dev
);
107 return sprintf(buf
, "%u\n", zram
->stats
.pages_zero
);
110 static ssize_t
orig_data_size_show(struct device
*dev
,
111 struct device_attribute
*attr
, char *buf
)
113 struct zram
*zram
= dev_to_zram(dev
);
115 return sprintf(buf
, "%llu\n",
116 (u64
)(zram
->stats
.pages_stored
) << PAGE_SHIFT
);
119 static ssize_t
compr_data_size_show(struct device
*dev
,
120 struct device_attribute
*attr
, char *buf
)
122 struct zram
*zram
= dev_to_zram(dev
);
124 return sprintf(buf
, "%llu\n",
125 (u64
)atomic64_read(&zram
->stats
.compr_size
));
128 static ssize_t
mem_used_total_show(struct device
*dev
,
129 struct device_attribute
*attr
, char *buf
)
132 struct zram
*zram
= dev_to_zram(dev
);
133 struct zram_meta
*meta
= zram
->meta
;
135 down_read(&zram
->init_lock
);
137 val
= zs_get_total_size_bytes(meta
->mem_pool
);
138 up_read(&zram
->init_lock
);
140 return sprintf(buf
, "%llu\n", val
);
143 static int zram_test_flag(struct zram_meta
*meta
, u32 index
,
144 enum zram_pageflags flag
)
146 return meta
->table
[index
].flags
& BIT(flag
);
149 static void zram_set_flag(struct zram_meta
*meta
, u32 index
,
150 enum zram_pageflags flag
)
152 meta
->table
[index
].flags
|= BIT(flag
);
155 static void zram_clear_flag(struct zram_meta
*meta
, u32 index
,
156 enum zram_pageflags flag
)
158 meta
->table
[index
].flags
&= ~BIT(flag
);
161 static inline int is_partial_io(struct bio_vec
*bvec
)
163 return bvec
->bv_len
!= PAGE_SIZE
;
167 * Check if request is within bounds and aligned on zram logical blocks.
169 static inline int valid_io_request(struct zram
*zram
, struct bio
*bio
)
171 u64 start
, end
, bound
;
173 /* unaligned request */
174 if (unlikely(bio
->bi_iter
.bi_sector
&
175 (ZRAM_SECTOR_PER_LOGICAL_BLOCK
- 1)))
177 if (unlikely(bio
->bi_iter
.bi_size
& (ZRAM_LOGICAL_BLOCK_SIZE
- 1)))
180 start
= bio
->bi_iter
.bi_sector
;
181 end
= start
+ (bio
->bi_iter
.bi_size
>> SECTOR_SHIFT
);
182 bound
= zram
->disksize
>> SECTOR_SHIFT
;
183 /* out of range range */
184 if (unlikely(start
>= bound
|| end
> bound
|| start
> end
))
187 /* I/O request is valid */
191 static void zram_meta_free(struct zram_meta
*meta
)
193 zs_destroy_pool(meta
->mem_pool
);
194 kfree(meta
->compress_workmem
);
195 free_pages((unsigned long)meta
->compress_buffer
, 1);
200 static struct zram_meta
*zram_meta_alloc(u64 disksize
)
203 struct zram_meta
*meta
= kmalloc(sizeof(*meta
), GFP_KERNEL
);
207 meta
->compress_workmem
= kzalloc(LZO1X_MEM_COMPRESS
, GFP_KERNEL
);
208 if (!meta
->compress_workmem
)
211 meta
->compress_buffer
=
212 (void *)__get_free_pages(GFP_KERNEL
| __GFP_ZERO
, 1);
213 if (!meta
->compress_buffer
) {
214 pr_err("Error allocating compressor buffer space\n");
218 num_pages
= disksize
>> PAGE_SHIFT
;
219 meta
->table
= vzalloc(num_pages
* sizeof(*meta
->table
));
221 pr_err("Error allocating zram address table\n");
225 meta
->mem_pool
= zs_create_pool(GFP_NOIO
| __GFP_HIGHMEM
);
226 if (!meta
->mem_pool
) {
227 pr_err("Error creating memory pool\n");
236 free_pages((unsigned long)meta
->compress_buffer
, 1);
238 kfree(meta
->compress_workmem
);
246 static void update_position(u32
*index
, int *offset
, struct bio_vec
*bvec
)
248 if (*offset
+ bvec
->bv_len
>= PAGE_SIZE
)
250 *offset
= (*offset
+ bvec
->bv_len
) % PAGE_SIZE
;
253 static int page_zero_filled(void *ptr
)
258 page
= (unsigned long *)ptr
;
260 for (pos
= 0; pos
!= PAGE_SIZE
/ sizeof(*page
); pos
++) {
268 static void handle_zero_page(struct bio_vec
*bvec
)
270 struct page
*page
= bvec
->bv_page
;
273 user_mem
= kmap_atomic(page
);
274 if (is_partial_io(bvec
))
275 memset(user_mem
+ bvec
->bv_offset
, 0, bvec
->bv_len
);
277 clear_page(user_mem
);
278 kunmap_atomic(user_mem
);
280 flush_dcache_page(page
);
283 static void zram_free_page(struct zram
*zram
, size_t index
)
285 struct zram_meta
*meta
= zram
->meta
;
286 unsigned long handle
= meta
->table
[index
].handle
;
287 u16 size
= meta
->table
[index
].size
;
289 if (unlikely(!handle
)) {
291 * No memory is allocated for zero filled pages.
292 * Simply clear zero page flag.
294 if (zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
295 zram_clear_flag(meta
, index
, ZRAM_ZERO
);
296 zram
->stats
.pages_zero
--;
301 if (unlikely(size
> max_zpage_size
))
302 zram
->stats
.bad_compress
--;
304 zs_free(meta
->mem_pool
, handle
);
306 if (size
<= PAGE_SIZE
/ 2)
307 zram
->stats
.good_compress
--;
309 atomic64_sub(meta
->table
[index
].size
, &zram
->stats
.compr_size
);
310 zram
->stats
.pages_stored
--;
312 meta
->table
[index
].handle
= 0;
313 meta
->table
[index
].size
= 0;
316 static int zram_decompress_page(struct zram
*zram
, char *mem
, u32 index
)
319 size_t clen
= PAGE_SIZE
;
321 struct zram_meta
*meta
= zram
->meta
;
322 unsigned long handle
= meta
->table
[index
].handle
;
324 if (!handle
|| zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
329 cmem
= zs_map_object(meta
->mem_pool
, handle
, ZS_MM_RO
);
330 if (meta
->table
[index
].size
== PAGE_SIZE
)
331 copy_page(mem
, cmem
);
333 ret
= lzo1x_decompress_safe(cmem
, meta
->table
[index
].size
,
335 zs_unmap_object(meta
->mem_pool
, handle
);
337 /* Should NEVER happen. Return bio error if it does. */
338 if (unlikely(ret
!= LZO_E_OK
)) {
339 pr_err("Decompression failed! err=%d, page=%u\n", ret
, index
);
340 atomic64_inc(&zram
->stats
.failed_reads
);
347 static int zram_bvec_read(struct zram
*zram
, struct bio_vec
*bvec
,
348 u32 index
, int offset
, struct bio
*bio
)
352 unsigned char *user_mem
, *uncmem
= NULL
;
353 struct zram_meta
*meta
= zram
->meta
;
354 page
= bvec
->bv_page
;
356 if (unlikely(!meta
->table
[index
].handle
) ||
357 zram_test_flag(meta
, index
, ZRAM_ZERO
)) {
358 handle_zero_page(bvec
);
362 if (is_partial_io(bvec
))
363 /* Use a temporary buffer to decompress the page */
364 uncmem
= kmalloc(PAGE_SIZE
, GFP_NOIO
);
366 user_mem
= kmap_atomic(page
);
367 if (!is_partial_io(bvec
))
371 pr_info("Unable to allocate temp memory\n");
376 ret
= zram_decompress_page(zram
, uncmem
, index
);
377 /* Should NEVER happen. Return bio error if it does. */
378 if (unlikely(ret
!= LZO_E_OK
))
381 if (is_partial_io(bvec
))
382 memcpy(user_mem
+ bvec
->bv_offset
, uncmem
+ offset
,
385 flush_dcache_page(page
);
388 kunmap_atomic(user_mem
);
389 if (is_partial_io(bvec
))
394 static int zram_bvec_write(struct zram
*zram
, struct bio_vec
*bvec
, u32 index
,
399 unsigned long handle
;
401 unsigned char *user_mem
, *cmem
, *src
, *uncmem
= NULL
;
402 struct zram_meta
*meta
= zram
->meta
;
404 page
= bvec
->bv_page
;
405 src
= meta
->compress_buffer
;
407 if (is_partial_io(bvec
)) {
409 * This is a partial IO. We need to read the full page
410 * before to write the changes.
412 uncmem
= kmalloc(PAGE_SIZE
, GFP_NOIO
);
417 ret
= zram_decompress_page(zram
, uncmem
, index
);
422 user_mem
= kmap_atomic(page
);
424 if (is_partial_io(bvec
)) {
425 memcpy(uncmem
+ offset
, user_mem
+ bvec
->bv_offset
,
427 kunmap_atomic(user_mem
);
433 if (page_zero_filled(uncmem
)) {
434 kunmap_atomic(user_mem
);
435 /* Free memory associated with this sector now. */
436 zram_free_page(zram
, index
);
438 zram
->stats
.pages_zero
++;
439 zram_set_flag(meta
, index
, ZRAM_ZERO
);
445 * zram_slot_free_notify could miss free so that let's
448 if (unlikely(meta
->table
[index
].handle
||
449 zram_test_flag(meta
, index
, ZRAM_ZERO
)))
450 zram_free_page(zram
, index
);
452 ret
= lzo1x_1_compress(uncmem
, PAGE_SIZE
, src
, &clen
,
453 meta
->compress_workmem
);
455 if (!is_partial_io(bvec
)) {
456 kunmap_atomic(user_mem
);
461 if (unlikely(ret
!= LZO_E_OK
)) {
462 pr_err("Compression failed! err=%d\n", ret
);
466 if (unlikely(clen
> max_zpage_size
)) {
467 zram
->stats
.bad_compress
++;
470 if (is_partial_io(bvec
))
474 handle
= zs_malloc(meta
->mem_pool
, clen
);
476 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
481 cmem
= zs_map_object(meta
->mem_pool
, handle
, ZS_MM_WO
);
483 if ((clen
== PAGE_SIZE
) && !is_partial_io(bvec
)) {
484 src
= kmap_atomic(page
);
485 copy_page(cmem
, src
);
488 memcpy(cmem
, src
, clen
);
491 zs_unmap_object(meta
->mem_pool
, handle
);
494 * Free memory associated with this sector
495 * before overwriting unused sectors.
497 zram_free_page(zram
, index
);
499 meta
->table
[index
].handle
= handle
;
500 meta
->table
[index
].size
= clen
;
503 atomic64_add(clen
, &zram
->stats
.compr_size
);
504 zram
->stats
.pages_stored
++;
505 if (clen
<= PAGE_SIZE
/ 2)
506 zram
->stats
.good_compress
++;
509 if (is_partial_io(bvec
))
513 atomic64_inc(&zram
->stats
.failed_writes
);
517 static void handle_pending_slot_free(struct zram
*zram
)
519 struct zram_slot_free
*free_rq
;
521 spin_lock(&zram
->slot_free_lock
);
522 while (zram
->slot_free_rq
) {
523 free_rq
= zram
->slot_free_rq
;
524 zram
->slot_free_rq
= free_rq
->next
;
525 zram_free_page(zram
, free_rq
->index
);
528 spin_unlock(&zram
->slot_free_lock
);
531 static int zram_bvec_rw(struct zram
*zram
, struct bio_vec
*bvec
, u32 index
,
532 int offset
, struct bio
*bio
, int rw
)
537 down_read(&zram
->lock
);
538 handle_pending_slot_free(zram
);
539 ret
= zram_bvec_read(zram
, bvec
, index
, offset
, bio
);
540 up_read(&zram
->lock
);
542 down_write(&zram
->lock
);
543 handle_pending_slot_free(zram
);
544 ret
= zram_bvec_write(zram
, bvec
, index
, offset
);
545 up_write(&zram
->lock
);
551 static void zram_reset_device(struct zram
*zram
, bool reset_capacity
)
554 struct zram_meta
*meta
;
556 down_write(&zram
->init_lock
);
557 if (!zram
->init_done
) {
558 up_write(&zram
->init_lock
);
562 flush_work(&zram
->free_work
);
567 /* Free all pages that are still in this zram device */
568 for (index
= 0; index
< zram
->disksize
>> PAGE_SHIFT
; index
++) {
569 unsigned long handle
= meta
->table
[index
].handle
;
573 zs_free(meta
->mem_pool
, handle
);
576 zram_meta_free(zram
->meta
);
579 memset(&zram
->stats
, 0, sizeof(zram
->stats
));
583 set_capacity(zram
->disk
, 0);
584 up_write(&zram
->init_lock
);
587 static void zram_init_device(struct zram
*zram
, struct zram_meta
*meta
)
589 if (zram
->disksize
> 2 * (totalram_pages
<< PAGE_SHIFT
)) {
591 "There is little point creating a zram of greater than "
592 "twice the size of memory since we expect a 2:1 compression "
593 "ratio. Note that zram uses about 0.1%% of the size of "
594 "the disk when not in use so a huge zram is "
596 "\tMemory Size: %lu kB\n"
597 "\tSize you selected: %llu kB\n"
598 "Continuing anyway ...\n",
599 (totalram_pages
<< PAGE_SHIFT
) >> 10, zram
->disksize
>> 10
603 /* zram devices sort of resembles non-rotational disks */
604 queue_flag_set_unlocked(QUEUE_FLAG_NONROT
, zram
->disk
->queue
);
609 pr_debug("Initialization done!\n");
612 static ssize_t
disksize_store(struct device
*dev
,
613 struct device_attribute
*attr
, const char *buf
, size_t len
)
616 struct zram_meta
*meta
;
617 struct zram
*zram
= dev_to_zram(dev
);
619 disksize
= memparse(buf
, NULL
);
623 disksize
= PAGE_ALIGN(disksize
);
624 meta
= zram_meta_alloc(disksize
);
625 down_write(&zram
->init_lock
);
626 if (zram
->init_done
) {
627 up_write(&zram
->init_lock
);
628 zram_meta_free(meta
);
629 pr_info("Cannot change disksize for initialized device\n");
633 zram
->disksize
= disksize
;
634 set_capacity(zram
->disk
, zram
->disksize
>> SECTOR_SHIFT
);
635 zram_init_device(zram
, meta
);
636 up_write(&zram
->init_lock
);
641 static ssize_t
reset_store(struct device
*dev
,
642 struct device_attribute
*attr
, const char *buf
, size_t len
)
645 unsigned short do_reset
;
647 struct block_device
*bdev
;
649 zram
= dev_to_zram(dev
);
650 bdev
= bdget_disk(zram
->disk
, 0);
655 /* Do not reset an active device! */
656 if (bdev
->bd_holders
) {
661 ret
= kstrtou16(buf
, 10, &do_reset
);
670 /* Make sure all pending I/O is finished */
674 zram_reset_device(zram
, true);
682 static void __zram_make_request(struct zram
*zram
, struct bio
*bio
, int rw
)
687 struct bvec_iter iter
;
691 atomic64_inc(&zram
->stats
.num_reads
);
694 atomic64_inc(&zram
->stats
.num_writes
);
698 index
= bio
->bi_iter
.bi_sector
>> SECTORS_PER_PAGE_SHIFT
;
699 offset
= (bio
->bi_iter
.bi_sector
&
700 (SECTORS_PER_PAGE
- 1)) << SECTOR_SHIFT
;
702 bio_for_each_segment(bvec
, bio
, iter
) {
703 int max_transfer_size
= PAGE_SIZE
- offset
;
705 if (bvec
.bv_len
> max_transfer_size
) {
707 * zram_bvec_rw() can only make operation on a single
708 * zram page. Split the bio vector.
712 bv
.bv_page
= bvec
.bv_page
;
713 bv
.bv_len
= max_transfer_size
;
714 bv
.bv_offset
= bvec
.bv_offset
;
716 if (zram_bvec_rw(zram
, &bv
, index
, offset
, bio
, rw
) < 0)
719 bv
.bv_len
= bvec
.bv_len
- max_transfer_size
;
720 bv
.bv_offset
+= max_transfer_size
;
721 if (zram_bvec_rw(zram
, &bv
, index
+1, 0, bio
, rw
) < 0)
724 if (zram_bvec_rw(zram
, &bvec
, index
, offset
, bio
, rw
)
728 update_position(&index
, &offset
, &bvec
);
731 set_bit(BIO_UPTODATE
, &bio
->bi_flags
);
740 * Handler function for all zram I/O requests.
742 static void zram_make_request(struct request_queue
*queue
, struct bio
*bio
)
744 struct zram
*zram
= queue
->queuedata
;
746 down_read(&zram
->init_lock
);
747 if (unlikely(!zram
->init_done
))
750 if (!valid_io_request(zram
, bio
)) {
751 atomic64_inc(&zram
->stats
.invalid_io
);
755 __zram_make_request(zram
, bio
, bio_data_dir(bio
));
756 up_read(&zram
->init_lock
);
761 up_read(&zram
->init_lock
);
765 static void zram_slot_free(struct work_struct
*work
)
769 zram
= container_of(work
, struct zram
, free_work
);
770 down_write(&zram
->lock
);
771 handle_pending_slot_free(zram
);
772 up_write(&zram
->lock
);
775 static void add_slot_free(struct zram
*zram
, struct zram_slot_free
*free_rq
)
777 spin_lock(&zram
->slot_free_lock
);
778 free_rq
->next
= zram
->slot_free_rq
;
779 zram
->slot_free_rq
= free_rq
;
780 spin_unlock(&zram
->slot_free_lock
);
783 static void zram_slot_free_notify(struct block_device
*bdev
,
787 struct zram_slot_free
*free_rq
;
789 zram
= bdev
->bd_disk
->private_data
;
790 atomic64_inc(&zram
->stats
.notify_free
);
792 free_rq
= kmalloc(sizeof(struct zram_slot_free
), GFP_ATOMIC
);
796 free_rq
->index
= index
;
797 add_slot_free(zram
, free_rq
);
798 schedule_work(&zram
->free_work
);
801 static const struct block_device_operations zram_devops
= {
802 .swap_slot_free_notify
= zram_slot_free_notify
,
806 static DEVICE_ATTR(disksize
, S_IRUGO
| S_IWUSR
,
807 disksize_show
, disksize_store
);
808 static DEVICE_ATTR(initstate
, S_IRUGO
, initstate_show
, NULL
);
809 static DEVICE_ATTR(reset
, S_IWUSR
, NULL
, reset_store
);
810 static DEVICE_ATTR(num_reads
, S_IRUGO
, num_reads_show
, NULL
);
811 static DEVICE_ATTR(num_writes
, S_IRUGO
, num_writes_show
, NULL
);
812 static DEVICE_ATTR(invalid_io
, S_IRUGO
, invalid_io_show
, NULL
);
813 static DEVICE_ATTR(notify_free
, S_IRUGO
, notify_free_show
, NULL
);
814 static DEVICE_ATTR(zero_pages
, S_IRUGO
, zero_pages_show
, NULL
);
815 static DEVICE_ATTR(orig_data_size
, S_IRUGO
, orig_data_size_show
, NULL
);
816 static DEVICE_ATTR(compr_data_size
, S_IRUGO
, compr_data_size_show
, NULL
);
817 static DEVICE_ATTR(mem_used_total
, S_IRUGO
, mem_used_total_show
, NULL
);
819 static struct attribute
*zram_disk_attrs
[] = {
820 &dev_attr_disksize
.attr
,
821 &dev_attr_initstate
.attr
,
822 &dev_attr_reset
.attr
,
823 &dev_attr_num_reads
.attr
,
824 &dev_attr_num_writes
.attr
,
825 &dev_attr_invalid_io
.attr
,
826 &dev_attr_notify_free
.attr
,
827 &dev_attr_zero_pages
.attr
,
828 &dev_attr_orig_data_size
.attr
,
829 &dev_attr_compr_data_size
.attr
,
830 &dev_attr_mem_used_total
.attr
,
834 static struct attribute_group zram_disk_attr_group
= {
835 .attrs
= zram_disk_attrs
,
838 static int create_device(struct zram
*zram
, int device_id
)
842 init_rwsem(&zram
->lock
);
843 init_rwsem(&zram
->init_lock
);
845 INIT_WORK(&zram
->free_work
, zram_slot_free
);
846 spin_lock_init(&zram
->slot_free_lock
);
847 zram
->slot_free_rq
= NULL
;
849 zram
->queue
= blk_alloc_queue(GFP_KERNEL
);
851 pr_err("Error allocating disk queue for device %d\n",
856 blk_queue_make_request(zram
->queue
, zram_make_request
);
857 zram
->queue
->queuedata
= zram
;
859 /* gendisk structure */
860 zram
->disk
= alloc_disk(1);
862 pr_warn("Error allocating disk structure for device %d\n",
867 zram
->disk
->major
= zram_major
;
868 zram
->disk
->first_minor
= device_id
;
869 zram
->disk
->fops
= &zram_devops
;
870 zram
->disk
->queue
= zram
->queue
;
871 zram
->disk
->private_data
= zram
;
872 snprintf(zram
->disk
->disk_name
, 16, "zram%d", device_id
);
874 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
875 set_capacity(zram
->disk
, 0);
878 * To ensure that we always get PAGE_SIZE aligned
879 * and n*PAGE_SIZED sized I/O requests.
881 blk_queue_physical_block_size(zram
->disk
->queue
, PAGE_SIZE
);
882 blk_queue_logical_block_size(zram
->disk
->queue
,
883 ZRAM_LOGICAL_BLOCK_SIZE
);
884 blk_queue_io_min(zram
->disk
->queue
, PAGE_SIZE
);
885 blk_queue_io_opt(zram
->disk
->queue
, PAGE_SIZE
);
887 add_disk(zram
->disk
);
889 ret
= sysfs_create_group(&disk_to_dev(zram
->disk
)->kobj
,
890 &zram_disk_attr_group
);
892 pr_warn("Error creating sysfs group");
900 del_gendisk(zram
->disk
);
901 put_disk(zram
->disk
);
903 blk_cleanup_queue(zram
->queue
);
908 static void destroy_device(struct zram
*zram
)
910 sysfs_remove_group(&disk_to_dev(zram
->disk
)->kobj
,
911 &zram_disk_attr_group
);
913 del_gendisk(zram
->disk
);
914 put_disk(zram
->disk
);
916 blk_cleanup_queue(zram
->queue
);
919 static int __init
zram_init(void)
923 if (num_devices
> max_num_devices
) {
924 pr_warn("Invalid value for num_devices: %u\n",
930 zram_major
= register_blkdev(0, "zram");
931 if (zram_major
<= 0) {
932 pr_warn("Unable to get major number\n");
937 /* Allocate the device array and initialize each one */
938 zram_devices
= kzalloc(num_devices
* sizeof(struct zram
), GFP_KERNEL
);
944 for (dev_id
= 0; dev_id
< num_devices
; dev_id
++) {
945 ret
= create_device(&zram_devices
[dev_id
], dev_id
);
950 pr_info("Created %u device(s) ...\n", num_devices
);
956 destroy_device(&zram_devices
[--dev_id
]);
959 unregister_blkdev(zram_major
, "zram");
964 static void __exit
zram_exit(void)
969 for (i
= 0; i
< num_devices
; i
++) {
970 zram
= &zram_devices
[i
];
972 destroy_device(zram
);
974 * Shouldn't access zram->disk after destroy_device
975 * because destroy_device already released zram->disk.
977 zram_reset_device(zram
, false);
980 unregister_blkdev(zram_major
, "zram");
983 pr_debug("Cleanup done!\n");
986 module_init(zram_init
);
987 module_exit(zram_exit
);
989 module_param(num_devices
, uint
, 0);
990 MODULE_PARM_DESC(num_devices
, "Number of zram devices");
992 MODULE_LICENSE("Dual BSD/GPL");
993 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
994 MODULE_DESCRIPTION("Compressed RAM Block Device");