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);
627 up_write(&zram->init_lock);
630 static ssize_t disksize_store(struct device *dev,
631 struct device_attribute *attr, const char *buf, size_t len)
635 struct zram_meta *meta;
636 struct zram *zram = dev_to_zram(dev);
639 disksize = memparse(buf, NULL);
643 disksize = PAGE_ALIGN(disksize);
644 meta = zram_meta_alloc(disksize);
648 comp = zcomp_create(zram->compressor, zram->max_comp_streams);
650 pr_info("Cannot initialise %s compressing backend\n",
656 down_write(&zram->init_lock);
657 if (init_done(zram)) {
658 pr_info("Cannot change disksize for initialized device\n");
660 goto out_destroy_comp;
665 zram->disksize = disksize;
666 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
667 up_write(&zram->init_lock);
671 up_write(&zram->init_lock);
674 zram_meta_free(meta);
678 static ssize_t reset_store(struct device *dev,
679 struct device_attribute *attr, const char *buf, size_t len)
682 unsigned short do_reset;
684 struct block_device *bdev;
686 zram = dev_to_zram(dev);
687 bdev = bdget_disk(zram->disk, 0);
692 /* Do not reset an active device! */
693 if (bdev->bd_holders) {
698 ret = kstrtou16(buf, 10, &do_reset);
707 /* Make sure all pending I/O is finished */
711 zram_reset_device(zram, true);
719 static void __zram_make_request(struct zram *zram, struct bio *bio)
724 struct bvec_iter iter;
726 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
727 offset = (bio->bi_iter.bi_sector &
728 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
730 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
731 zram_bio_discard(zram, index, offset, bio);
736 bio_for_each_segment(bvec, bio, iter) {
737 int max_transfer_size = PAGE_SIZE - offset;
739 if (bvec.bv_len > max_transfer_size) {
741 * zram_bvec_rw() can only make operation on a single
742 * zram page. Split the bio vector.
746 bv.bv_page = bvec.bv_page;
747 bv.bv_len = max_transfer_size;
748 bv.bv_offset = bvec.bv_offset;
750 if (zram_bvec_rw(zram, &bv, index, offset, bio) < 0)
753 bv.bv_len = bvec.bv_len - max_transfer_size;
754 bv.bv_offset += max_transfer_size;
755 if (zram_bvec_rw(zram, &bv, index + 1, 0, bio) < 0)
758 if (zram_bvec_rw(zram, &bvec, index, offset, bio) < 0)
761 update_position(&index, &offset, &bvec);
764 set_bit(BIO_UPTODATE, &bio->bi_flags);
773 * Handler function for all zram I/O requests.
775 static void zram_make_request(struct request_queue *queue, struct bio *bio)
777 struct zram *zram = queue->queuedata;
779 down_read(&zram->init_lock);
780 if (unlikely(!init_done(zram)))
783 if (!valid_io_request(zram, bio)) {
784 atomic64_inc(&zram->stats.invalid_io);
788 __zram_make_request(zram, bio);
789 up_read(&zram->init_lock);
794 up_read(&zram->init_lock);
798 static void zram_slot_free_notify(struct block_device *bdev,
802 struct zram_meta *meta;
804 zram = bdev->bd_disk->private_data;
807 write_lock(&meta->tb_lock);
808 zram_free_page(zram, index);
809 write_unlock(&meta->tb_lock);
810 atomic64_inc(&zram->stats.notify_free);
813 static const struct block_device_operations zram_devops = {
814 .swap_slot_free_notify = zram_slot_free_notify,
818 static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
819 disksize_show, disksize_store);
820 static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
821 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
822 static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
823 static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
824 static DEVICE_ATTR(max_comp_streams, S_IRUGO | S_IWUSR,
825 max_comp_streams_show, max_comp_streams_store);
826 static DEVICE_ATTR(comp_algorithm, S_IRUGO | S_IWUSR,
827 comp_algorithm_show, comp_algorithm_store);
829 ZRAM_ATTR_RO(num_reads);
830 ZRAM_ATTR_RO(num_writes);
831 ZRAM_ATTR_RO(failed_reads);
832 ZRAM_ATTR_RO(failed_writes);
833 ZRAM_ATTR_RO(invalid_io);
834 ZRAM_ATTR_RO(notify_free);
835 ZRAM_ATTR_RO(zero_pages);
836 ZRAM_ATTR_RO(compr_data_size);
838 static struct attribute *zram_disk_attrs[] = {
839 &dev_attr_disksize.attr,
840 &dev_attr_initstate.attr,
841 &dev_attr_reset.attr,
842 &dev_attr_num_reads.attr,
843 &dev_attr_num_writes.attr,
844 &dev_attr_failed_reads.attr,
845 &dev_attr_failed_writes.attr,
846 &dev_attr_invalid_io.attr,
847 &dev_attr_notify_free.attr,
848 &dev_attr_zero_pages.attr,
849 &dev_attr_orig_data_size.attr,
850 &dev_attr_compr_data_size.attr,
851 &dev_attr_mem_used_total.attr,
852 &dev_attr_max_comp_streams.attr,
853 &dev_attr_comp_algorithm.attr,
857 static struct attribute_group zram_disk_attr_group = {
858 .attrs = zram_disk_attrs,
861 static int create_device(struct zram *zram, int device_id)
865 init_rwsem(&zram->init_lock);
867 zram->queue = blk_alloc_queue(GFP_KERNEL);
869 pr_err("Error allocating disk queue for device %d\n",
874 blk_queue_make_request(zram->queue, zram_make_request);
875 zram->queue->queuedata = zram;
877 /* gendisk structure */
878 zram->disk = alloc_disk(1);
880 pr_warn("Error allocating disk structure for device %d\n",
885 zram->disk->major = zram_major;
886 zram->disk->first_minor = device_id;
887 zram->disk->fops = &zram_devops;
888 zram->disk->queue = zram->queue;
889 zram->disk->private_data = zram;
890 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
892 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
893 set_capacity(zram->disk, 0);
894 /* zram devices sort of resembles non-rotational disks */
895 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
897 * To ensure that we always get PAGE_SIZE aligned
898 * and n*PAGE_SIZED sized I/O requests.
900 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
901 blk_queue_logical_block_size(zram->disk->queue,
902 ZRAM_LOGICAL_BLOCK_SIZE);
903 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
904 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
905 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
906 zram->disk->queue->limits.max_discard_sectors = UINT_MAX;
908 * zram_bio_discard() will clear all logical blocks if logical block
909 * size is identical with physical block size(PAGE_SIZE). But if it is
910 * different, we will skip discarding some parts of logical blocks in
911 * the part of the request range which isn't aligned to physical block
912 * size. So we can't ensure that all discarded logical blocks are
915 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
916 zram->disk->queue->limits.discard_zeroes_data = 1;
918 zram->disk->queue->limits.discard_zeroes_data = 0;
919 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
921 add_disk(zram->disk);
923 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
924 &zram_disk_attr_group);
926 pr_warn("Error creating sysfs group");
929 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
931 zram->max_comp_streams = 1;
935 del_gendisk(zram->disk);
936 put_disk(zram->disk);
938 blk_cleanup_queue(zram->queue);
943 static void destroy_device(struct zram *zram)
945 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
946 &zram_disk_attr_group);
948 del_gendisk(zram->disk);
949 put_disk(zram->disk);
951 blk_cleanup_queue(zram->queue);
954 static int __init zram_init(void)
958 if (num_devices > max_num_devices) {
959 pr_warn("Invalid value for num_devices: %u\n",
965 zram_major = register_blkdev(0, "zram");
966 if (zram_major <= 0) {
967 pr_warn("Unable to get major number\n");
972 /* Allocate the device array and initialize each one */
973 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
979 for (dev_id = 0; dev_id < num_devices; dev_id++) {
980 ret = create_device(&zram_devices[dev_id], dev_id);
985 pr_info("Created %u device(s) ...\n", num_devices);
991 destroy_device(&zram_devices[--dev_id]);
994 unregister_blkdev(zram_major, "zram");
999 static void __exit zram_exit(void)
1004 for (i = 0; i < num_devices; i++) {
1005 zram = &zram_devices[i];
1007 destroy_device(zram);
1009 * Shouldn't access zram->disk after destroy_device
1010 * because destroy_device already released zram->disk.
1012 zram_reset_device(zram, false);
1015 unregister_blkdev(zram_major, "zram");
1017 kfree(zram_devices);
1018 pr_debug("Cleanup done!\n");
1021 module_init(zram_init);
1022 module_exit(zram_exit);
1024 module_param(num_devices, uint, 0);
1025 MODULE_PARM_DESC(num_devices, "Number of zram devices");
1027 MODULE_LICENSE("Dual BSD/GPL");
1028 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1029 MODULE_DESCRIPTION("Compressed RAM Block Device");