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_pages(meta->mem_pool);
107 up_read(&zram->init_lock);
109 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
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].value & BIT(flag);
189 static void zram_set_flag(struct zram_meta *meta, u32 index,
190 enum zram_pageflags flag)
192 meta->table[index].value |= BIT(flag);
195 static void zram_clear_flag(struct zram_meta *meta, u32 index,
196 enum zram_pageflags flag)
198 meta->table[index].value &= ~BIT(flag);
201 static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
203 return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
206 static void zram_set_obj_size(struct zram_meta *meta,
207 u32 index, size_t size)
209 unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT;
211 meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
214 static inline int is_partial_io(struct bio_vec *bvec)
216 return bvec->bv_len != PAGE_SIZE;
220 * Check if request is within bounds and aligned on zram logical blocks.
222 static inline int valid_io_request(struct zram *zram, struct bio *bio)
224 u64 start, end, bound;
226 /* unaligned request */
227 if (unlikely(bio->bi_iter.bi_sector &
228 (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
230 if (unlikely(bio->bi_iter.bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
233 start = bio->bi_iter.bi_sector;
234 end = start + (bio->bi_iter.bi_size >> SECTOR_SHIFT);
235 bound = zram->disksize >> SECTOR_SHIFT;
236 /* out of range range */
237 if (unlikely(start >= bound || end > bound || start > end))
240 /* I/O request is valid */
244 static void zram_meta_free(struct zram_meta *meta)
246 zs_destroy_pool(meta->mem_pool);
251 static struct zram_meta *zram_meta_alloc(u64 disksize)
254 struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
258 num_pages = disksize >> PAGE_SHIFT;
259 meta->table = vzalloc(num_pages * sizeof(*meta->table));
261 pr_err("Error allocating zram address table\n");
265 meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
266 if (!meta->mem_pool) {
267 pr_err("Error creating memory pool\n");
282 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
284 if (*offset + bvec->bv_len >= PAGE_SIZE)
286 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
289 static int page_zero_filled(void *ptr)
294 page = (unsigned long *)ptr;
296 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
304 static void handle_zero_page(struct bio_vec *bvec)
306 struct page *page = bvec->bv_page;
309 user_mem = kmap_atomic(page);
310 if (is_partial_io(bvec))
311 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
313 clear_page(user_mem);
314 kunmap_atomic(user_mem);
316 flush_dcache_page(page);
321 * To protect concurrent access to the same index entry,
322 * caller should hold this table index entry's bit_spinlock to
323 * indicate this index entry is accessing.
325 static void zram_free_page(struct zram *zram, size_t index)
327 struct zram_meta *meta = zram->meta;
328 unsigned long handle = meta->table[index].handle;
330 if (unlikely(!handle)) {
332 * No memory is allocated for zero filled pages.
333 * Simply clear zero page flag.
335 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
336 zram_clear_flag(meta, index, ZRAM_ZERO);
337 atomic64_dec(&zram->stats.zero_pages);
342 zs_free(meta->mem_pool, handle);
344 atomic64_sub(zram_get_obj_size(meta, index),
345 &zram->stats.compr_data_size);
346 atomic64_dec(&zram->stats.pages_stored);
348 meta->table[index].handle = 0;
349 zram_set_obj_size(meta, index, 0);
352 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
356 struct zram_meta *meta = zram->meta;
357 unsigned long handle;
360 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
361 handle = meta->table[index].handle;
362 size = zram_get_obj_size(meta, index);
364 if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
365 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
370 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
371 if (size == PAGE_SIZE)
372 copy_page(mem, cmem);
374 ret = zcomp_decompress(zram->comp, cmem, size, mem);
375 zs_unmap_object(meta->mem_pool, handle);
376 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
378 /* Should NEVER happen. Return bio error if it does. */
380 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
387 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
388 u32 index, int offset, struct bio *bio)
392 unsigned char *user_mem, *uncmem = NULL;
393 struct zram_meta *meta = zram->meta;
394 page = bvec->bv_page;
396 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
397 if (unlikely(!meta->table[index].handle) ||
398 zram_test_flag(meta, index, ZRAM_ZERO)) {
399 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
400 handle_zero_page(bvec);
403 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
405 if (is_partial_io(bvec))
406 /* Use a temporary buffer to decompress the page */
407 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
409 user_mem = kmap_atomic(page);
410 if (!is_partial_io(bvec))
414 pr_info("Unable to allocate temp memory\n");
419 ret = zram_decompress_page(zram, uncmem, index);
420 /* Should NEVER happen. Return bio error if it does. */
424 if (is_partial_io(bvec))
425 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
428 flush_dcache_page(page);
431 kunmap_atomic(user_mem);
432 if (is_partial_io(bvec))
437 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
442 unsigned long handle;
444 unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
445 struct zram_meta *meta = zram->meta;
446 struct zcomp_strm *zstrm;
449 page = bvec->bv_page;
450 if (is_partial_io(bvec)) {
452 * This is a partial IO. We need to read the full page
453 * before to write the changes.
455 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
460 ret = zram_decompress_page(zram, uncmem, index);
465 zstrm = zcomp_strm_find(zram->comp);
467 user_mem = kmap_atomic(page);
469 if (is_partial_io(bvec)) {
470 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
472 kunmap_atomic(user_mem);
478 if (page_zero_filled(uncmem)) {
479 kunmap_atomic(user_mem);
480 /* Free memory associated with this sector now. */
481 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
482 zram_free_page(zram, index);
483 zram_set_flag(meta, index, ZRAM_ZERO);
484 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
486 atomic64_inc(&zram->stats.zero_pages);
491 ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen);
492 if (!is_partial_io(bvec)) {
493 kunmap_atomic(user_mem);
499 pr_err("Compression failed! err=%d\n", ret);
503 if (unlikely(clen > max_zpage_size)) {
505 if (is_partial_io(bvec))
509 handle = zs_malloc(meta->mem_pool, clen);
511 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
516 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
518 if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
519 src = kmap_atomic(page);
520 copy_page(cmem, src);
523 memcpy(cmem, src, clen);
526 zcomp_strm_release(zram->comp, zstrm);
528 zs_unmap_object(meta->mem_pool, handle);
531 * Free memory associated with this sector
532 * before overwriting unused sectors.
534 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
535 zram_free_page(zram, index);
537 meta->table[index].handle = handle;
538 zram_set_obj_size(meta, index, clen);
539 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
542 atomic64_add(clen, &zram->stats.compr_data_size);
543 atomic64_inc(&zram->stats.pages_stored);
546 zcomp_strm_release(zram->comp, zstrm);
547 if (is_partial_io(bvec))
552 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
553 int offset, struct bio *bio)
556 int rw = bio_data_dir(bio);
559 atomic64_inc(&zram->stats.num_reads);
560 ret = zram_bvec_read(zram, bvec, index, offset, bio);
562 atomic64_inc(&zram->stats.num_writes);
563 ret = zram_bvec_write(zram, bvec, index, offset);
568 atomic64_inc(&zram->stats.failed_reads);
570 atomic64_inc(&zram->stats.failed_writes);
577 * zram_bio_discard - handler on discard request
578 * @index: physical block index in PAGE_SIZE units
579 * @offset: byte offset within physical block
581 static void zram_bio_discard(struct zram *zram, u32 index,
582 int offset, struct bio *bio)
584 size_t n = bio->bi_iter.bi_size;
585 struct zram_meta *meta = zram->meta;
588 * zram manages data in physical block size units. Because logical block
589 * size isn't identical with physical block size on some arch, we
590 * could get a discard request pointing to a specific offset within a
591 * certain physical block. Although we can handle this request by
592 * reading that physiclal block and decompressing and partially zeroing
593 * and re-compressing and then re-storing it, this isn't reasonable
594 * because our intent with a discard request is to save memory. So
595 * skipping this logical block is appropriate here.
598 if (n <= (PAGE_SIZE - offset))
601 n -= (PAGE_SIZE - offset);
605 while (n >= PAGE_SIZE) {
606 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
607 zram_free_page(zram, index);
608 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
614 static void zram_reset_device(struct zram *zram, bool reset_capacity)
617 struct zram_meta *meta;
619 down_write(&zram->init_lock);
620 if (!init_done(zram)) {
621 up_write(&zram->init_lock);
626 /* Free all pages that are still in this zram device */
627 for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
628 unsigned long handle = meta->table[index].handle;
632 zs_free(meta->mem_pool, handle);
635 zcomp_destroy(zram->comp);
636 zram->max_comp_streams = 1;
638 zram_meta_free(zram->meta);
641 memset(&zram->stats, 0, sizeof(zram->stats));
645 set_capacity(zram->disk, 0);
647 up_write(&zram->init_lock);
650 * Revalidate disk out of the init_lock to avoid lockdep splat.
651 * It's okay because disk's capacity is protected by init_lock
652 * so that revalidate_disk always sees up-to-date capacity.
655 revalidate_disk(zram->disk);
658 static ssize_t disksize_store(struct device *dev,
659 struct device_attribute *attr, const char *buf, size_t len)
663 struct zram_meta *meta;
664 struct zram *zram = dev_to_zram(dev);
667 disksize = memparse(buf, NULL);
671 disksize = PAGE_ALIGN(disksize);
672 meta = zram_meta_alloc(disksize);
676 comp = zcomp_create(zram->compressor, zram->max_comp_streams);
678 pr_info("Cannot initialise %s compressing backend\n",
684 down_write(&zram->init_lock);
685 if (init_done(zram)) {
686 pr_info("Cannot change disksize for initialized device\n");
688 goto out_destroy_comp;
693 zram->disksize = disksize;
694 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
695 up_write(&zram->init_lock);
698 * Revalidate disk out of the init_lock to avoid lockdep splat.
699 * It's okay because disk's capacity is protected by init_lock
700 * so that revalidate_disk always sees up-to-date capacity.
702 revalidate_disk(zram->disk);
707 up_write(&zram->init_lock);
710 zram_meta_free(meta);
714 static ssize_t reset_store(struct device *dev,
715 struct device_attribute *attr, const char *buf, size_t len)
718 unsigned short do_reset;
720 struct block_device *bdev;
722 zram = dev_to_zram(dev);
723 bdev = bdget_disk(zram->disk, 0);
728 /* Do not reset an active device! */
729 if (bdev->bd_holders) {
734 ret = kstrtou16(buf, 10, &do_reset);
743 /* Make sure all pending I/O is finished */
747 zram_reset_device(zram, true);
755 static void __zram_make_request(struct zram *zram, struct bio *bio)
760 struct bvec_iter iter;
762 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
763 offset = (bio->bi_iter.bi_sector &
764 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
766 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
767 zram_bio_discard(zram, index, offset, bio);
772 bio_for_each_segment(bvec, bio, iter) {
773 int max_transfer_size = PAGE_SIZE - offset;
775 if (bvec.bv_len > max_transfer_size) {
777 * zram_bvec_rw() can only make operation on a single
778 * zram page. Split the bio vector.
782 bv.bv_page = bvec.bv_page;
783 bv.bv_len = max_transfer_size;
784 bv.bv_offset = bvec.bv_offset;
786 if (zram_bvec_rw(zram, &bv, index, offset, bio) < 0)
789 bv.bv_len = bvec.bv_len - max_transfer_size;
790 bv.bv_offset += max_transfer_size;
791 if (zram_bvec_rw(zram, &bv, index + 1, 0, bio) < 0)
794 if (zram_bvec_rw(zram, &bvec, index, offset, bio) < 0)
797 update_position(&index, &offset, &bvec);
800 set_bit(BIO_UPTODATE, &bio->bi_flags);
809 * Handler function for all zram I/O requests.
811 static void zram_make_request(struct request_queue *queue, struct bio *bio)
813 struct zram *zram = queue->queuedata;
815 down_read(&zram->init_lock);
816 if (unlikely(!init_done(zram)))
819 if (!valid_io_request(zram, bio)) {
820 atomic64_inc(&zram->stats.invalid_io);
824 __zram_make_request(zram, bio);
825 up_read(&zram->init_lock);
830 up_read(&zram->init_lock);
834 static void zram_slot_free_notify(struct block_device *bdev,
838 struct zram_meta *meta;
840 zram = bdev->bd_disk->private_data;
843 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
844 zram_free_page(zram, index);
845 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
846 atomic64_inc(&zram->stats.notify_free);
849 static const struct block_device_operations zram_devops = {
850 .swap_slot_free_notify = zram_slot_free_notify,
854 static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
855 disksize_show, disksize_store);
856 static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
857 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
858 static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
859 static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
860 static DEVICE_ATTR(max_comp_streams, S_IRUGO | S_IWUSR,
861 max_comp_streams_show, max_comp_streams_store);
862 static DEVICE_ATTR(comp_algorithm, S_IRUGO | S_IWUSR,
863 comp_algorithm_show, comp_algorithm_store);
865 ZRAM_ATTR_RO(num_reads);
866 ZRAM_ATTR_RO(num_writes);
867 ZRAM_ATTR_RO(failed_reads);
868 ZRAM_ATTR_RO(failed_writes);
869 ZRAM_ATTR_RO(invalid_io);
870 ZRAM_ATTR_RO(notify_free);
871 ZRAM_ATTR_RO(zero_pages);
872 ZRAM_ATTR_RO(compr_data_size);
874 static struct attribute *zram_disk_attrs[] = {
875 &dev_attr_disksize.attr,
876 &dev_attr_initstate.attr,
877 &dev_attr_reset.attr,
878 &dev_attr_num_reads.attr,
879 &dev_attr_num_writes.attr,
880 &dev_attr_failed_reads.attr,
881 &dev_attr_failed_writes.attr,
882 &dev_attr_invalid_io.attr,
883 &dev_attr_notify_free.attr,
884 &dev_attr_zero_pages.attr,
885 &dev_attr_orig_data_size.attr,
886 &dev_attr_compr_data_size.attr,
887 &dev_attr_mem_used_total.attr,
888 &dev_attr_max_comp_streams.attr,
889 &dev_attr_comp_algorithm.attr,
893 static struct attribute_group zram_disk_attr_group = {
894 .attrs = zram_disk_attrs,
897 static int create_device(struct zram *zram, int device_id)
901 init_rwsem(&zram->init_lock);
903 zram->queue = blk_alloc_queue(GFP_KERNEL);
905 pr_err("Error allocating disk queue for device %d\n",
910 blk_queue_make_request(zram->queue, zram_make_request);
911 zram->queue->queuedata = zram;
913 /* gendisk structure */
914 zram->disk = alloc_disk(1);
916 pr_warn("Error allocating disk structure for device %d\n",
921 zram->disk->major = zram_major;
922 zram->disk->first_minor = device_id;
923 zram->disk->fops = &zram_devops;
924 zram->disk->queue = zram->queue;
925 zram->disk->private_data = zram;
926 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
928 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
929 set_capacity(zram->disk, 0);
930 /* zram devices sort of resembles non-rotational disks */
931 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
933 * To ensure that we always get PAGE_SIZE aligned
934 * and n*PAGE_SIZED sized I/O requests.
936 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
937 blk_queue_logical_block_size(zram->disk->queue,
938 ZRAM_LOGICAL_BLOCK_SIZE);
939 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
940 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
941 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
942 zram->disk->queue->limits.max_discard_sectors = UINT_MAX;
944 * zram_bio_discard() will clear all logical blocks if logical block
945 * size is identical with physical block size(PAGE_SIZE). But if it is
946 * different, we will skip discarding some parts of logical blocks in
947 * the part of the request range which isn't aligned to physical block
948 * size. So we can't ensure that all discarded logical blocks are
951 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
952 zram->disk->queue->limits.discard_zeroes_data = 1;
954 zram->disk->queue->limits.discard_zeroes_data = 0;
955 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
957 add_disk(zram->disk);
959 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
960 &zram_disk_attr_group);
962 pr_warn("Error creating sysfs group");
965 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
967 zram->max_comp_streams = 1;
971 del_gendisk(zram->disk);
972 put_disk(zram->disk);
974 blk_cleanup_queue(zram->queue);
979 static void destroy_device(struct zram *zram)
981 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
982 &zram_disk_attr_group);
984 del_gendisk(zram->disk);
985 put_disk(zram->disk);
987 blk_cleanup_queue(zram->queue);
990 static int __init zram_init(void)
994 if (num_devices > max_num_devices) {
995 pr_warn("Invalid value for num_devices: %u\n",
1001 zram_major = register_blkdev(0, "zram");
1002 if (zram_major <= 0) {
1003 pr_warn("Unable to get major number\n");
1008 /* Allocate the device array and initialize each one */
1009 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
1010 if (!zram_devices) {
1015 for (dev_id = 0; dev_id < num_devices; dev_id++) {
1016 ret = create_device(&zram_devices[dev_id], dev_id);
1021 pr_info("Created %u device(s) ...\n", num_devices);
1027 destroy_device(&zram_devices[--dev_id]);
1028 kfree(zram_devices);
1030 unregister_blkdev(zram_major, "zram");
1035 static void __exit zram_exit(void)
1040 for (i = 0; i < num_devices; i++) {
1041 zram = &zram_devices[i];
1043 destroy_device(zram);
1045 * Shouldn't access zram->disk after destroy_device
1046 * because destroy_device already released zram->disk.
1048 zram_reset_device(zram, false);
1051 unregister_blkdev(zram_major, "zram");
1053 kfree(zram_devices);
1054 pr_debug("Cleanup done!\n");
1057 module_init(zram_init);
1058 module_exit(zram_exit);
1060 module_param(num_devices, uint, 0);
1061 MODULE_PARM_DESC(num_devices, "Number of zram devices");
1063 MODULE_LICENSE("Dual BSD/GPL");
1064 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1065 MODULE_DESCRIPTION("Compressed RAM Block Device");