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 mem_limit_show(struct device *dev,
126 struct device_attribute *attr, char *buf)
129 struct zram *zram = dev_to_zram(dev);
131 down_read(&zram->init_lock);
132 val = zram->limit_pages;
133 up_read(&zram->init_lock);
135 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
138 static ssize_t mem_limit_store(struct device *dev,
139 struct device_attribute *attr, const char *buf, size_t len)
143 struct zram *zram = dev_to_zram(dev);
145 limit = memparse(buf, &tmp);
146 if (buf == tmp) /* no chars parsed, invalid input */
149 down_write(&zram->init_lock);
150 zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
151 up_write(&zram->init_lock);
156 static ssize_t mem_used_max_show(struct device *dev,
157 struct device_attribute *attr, char *buf)
160 struct zram *zram = dev_to_zram(dev);
162 down_read(&zram->init_lock);
164 val = atomic_long_read(&zram->stats.max_used_pages);
165 up_read(&zram->init_lock);
167 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
170 static ssize_t mem_used_max_store(struct device *dev,
171 struct device_attribute *attr, const char *buf, size_t len)
175 struct zram *zram = dev_to_zram(dev);
176 struct zram_meta *meta = zram->meta;
178 err = kstrtoul(buf, 10, &val);
182 down_read(&zram->init_lock);
184 atomic_long_set(&zram->stats.max_used_pages,
185 zs_get_total_pages(meta->mem_pool));
186 up_read(&zram->init_lock);
191 static ssize_t max_comp_streams_store(struct device *dev,
192 struct device_attribute *attr, const char *buf, size_t len)
195 struct zram *zram = dev_to_zram(dev);
198 ret = kstrtoint(buf, 0, &num);
204 down_write(&zram->init_lock);
205 if (init_done(zram)) {
206 if (!zcomp_set_max_streams(zram->comp, num)) {
207 pr_info("Cannot change max compression streams\n");
213 zram->max_comp_streams = num;
216 up_write(&zram->init_lock);
220 static ssize_t comp_algorithm_show(struct device *dev,
221 struct device_attribute *attr, char *buf)
224 struct zram *zram = dev_to_zram(dev);
226 down_read(&zram->init_lock);
227 sz = zcomp_available_show(zram->compressor, buf);
228 up_read(&zram->init_lock);
233 static ssize_t comp_algorithm_store(struct device *dev,
234 struct device_attribute *attr, const char *buf, size_t len)
236 struct zram *zram = dev_to_zram(dev);
237 down_write(&zram->init_lock);
238 if (init_done(zram)) {
239 up_write(&zram->init_lock);
240 pr_info("Can't change algorithm for initialized device\n");
243 strlcpy(zram->compressor, buf, sizeof(zram->compressor));
244 up_write(&zram->init_lock);
248 /* flag operations needs meta->tb_lock */
249 static int zram_test_flag(struct zram_meta *meta, u32 index,
250 enum zram_pageflags flag)
252 return meta->table[index].value & BIT(flag);
255 static void zram_set_flag(struct zram_meta *meta, u32 index,
256 enum zram_pageflags flag)
258 meta->table[index].value |= BIT(flag);
261 static void zram_clear_flag(struct zram_meta *meta, u32 index,
262 enum zram_pageflags flag)
264 meta->table[index].value &= ~BIT(flag);
267 static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
269 return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
272 static void zram_set_obj_size(struct zram_meta *meta,
273 u32 index, size_t size)
275 unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT;
277 meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
280 static inline int is_partial_io(struct bio_vec *bvec)
282 return bvec->bv_len != PAGE_SIZE;
286 * Check if request is within bounds and aligned on zram logical blocks.
288 static inline int valid_io_request(struct zram *zram, struct bio *bio)
290 u64 start, end, bound;
292 /* unaligned request */
293 if (unlikely(bio->bi_iter.bi_sector &
294 (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
296 if (unlikely(bio->bi_iter.bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
299 start = bio->bi_iter.bi_sector;
300 end = start + (bio->bi_iter.bi_size >> SECTOR_SHIFT);
301 bound = zram->disksize >> SECTOR_SHIFT;
302 /* out of range range */
303 if (unlikely(start >= bound || end > bound || start > end))
306 /* I/O request is valid */
310 static void zram_meta_free(struct zram_meta *meta)
312 zs_destroy_pool(meta->mem_pool);
317 static struct zram_meta *zram_meta_alloc(u64 disksize)
320 struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
324 num_pages = disksize >> PAGE_SHIFT;
325 meta->table = vzalloc(num_pages * sizeof(*meta->table));
327 pr_err("Error allocating zram address table\n");
331 meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
332 if (!meta->mem_pool) {
333 pr_err("Error creating memory pool\n");
348 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
350 if (*offset + bvec->bv_len >= PAGE_SIZE)
352 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
355 static int page_zero_filled(void *ptr)
360 page = (unsigned long *)ptr;
362 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
370 static void handle_zero_page(struct bio_vec *bvec)
372 struct page *page = bvec->bv_page;
375 user_mem = kmap_atomic(page);
376 if (is_partial_io(bvec))
377 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
379 clear_page(user_mem);
380 kunmap_atomic(user_mem);
382 flush_dcache_page(page);
387 * To protect concurrent access to the same index entry,
388 * caller should hold this table index entry's bit_spinlock to
389 * indicate this index entry is accessing.
391 static void zram_free_page(struct zram *zram, size_t index)
393 struct zram_meta *meta = zram->meta;
394 unsigned long handle = meta->table[index].handle;
396 if (unlikely(!handle)) {
398 * No memory is allocated for zero filled pages.
399 * Simply clear zero page flag.
401 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
402 zram_clear_flag(meta, index, ZRAM_ZERO);
403 atomic64_dec(&zram->stats.zero_pages);
408 zs_free(meta->mem_pool, handle);
410 atomic64_sub(zram_get_obj_size(meta, index),
411 &zram->stats.compr_data_size);
412 atomic64_dec(&zram->stats.pages_stored);
414 meta->table[index].handle = 0;
415 zram_set_obj_size(meta, index, 0);
418 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
422 struct zram_meta *meta = zram->meta;
423 unsigned long handle;
426 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
427 handle = meta->table[index].handle;
428 size = zram_get_obj_size(meta, index);
430 if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
431 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
436 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
437 if (size == PAGE_SIZE)
438 copy_page(mem, cmem);
440 ret = zcomp_decompress(zram->comp, cmem, size, mem);
441 zs_unmap_object(meta->mem_pool, handle);
442 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
444 /* Should NEVER happen. Return bio error if it does. */
446 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
453 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
454 u32 index, int offset, struct bio *bio)
458 unsigned char *user_mem, *uncmem = NULL;
459 struct zram_meta *meta = zram->meta;
460 page = bvec->bv_page;
462 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
463 if (unlikely(!meta->table[index].handle) ||
464 zram_test_flag(meta, index, ZRAM_ZERO)) {
465 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
466 handle_zero_page(bvec);
469 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
471 if (is_partial_io(bvec))
472 /* Use a temporary buffer to decompress the page */
473 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
475 user_mem = kmap_atomic(page);
476 if (!is_partial_io(bvec))
480 pr_info("Unable to allocate temp memory\n");
485 ret = zram_decompress_page(zram, uncmem, index);
486 /* Should NEVER happen. Return bio error if it does. */
490 if (is_partial_io(bvec))
491 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
494 flush_dcache_page(page);
497 kunmap_atomic(user_mem);
498 if (is_partial_io(bvec))
503 static inline void update_used_max(struct zram *zram,
504 const unsigned long pages)
506 int old_max, cur_max;
508 old_max = atomic_long_read(&zram->stats.max_used_pages);
513 old_max = atomic_long_cmpxchg(
514 &zram->stats.max_used_pages, cur_max, pages);
515 } while (old_max != cur_max);
518 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
523 unsigned long handle;
525 unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
526 struct zram_meta *meta = zram->meta;
527 struct zcomp_strm *zstrm;
529 unsigned long alloced_pages;
531 page = bvec->bv_page;
532 if (is_partial_io(bvec)) {
534 * This is a partial IO. We need to read the full page
535 * before to write the changes.
537 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
542 ret = zram_decompress_page(zram, uncmem, index);
547 zstrm = zcomp_strm_find(zram->comp);
549 user_mem = kmap_atomic(page);
551 if (is_partial_io(bvec)) {
552 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
554 kunmap_atomic(user_mem);
560 if (page_zero_filled(uncmem)) {
561 kunmap_atomic(user_mem);
562 /* Free memory associated with this sector now. */
563 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
564 zram_free_page(zram, index);
565 zram_set_flag(meta, index, ZRAM_ZERO);
566 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
568 atomic64_inc(&zram->stats.zero_pages);
573 ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen);
574 if (!is_partial_io(bvec)) {
575 kunmap_atomic(user_mem);
581 pr_err("Compression failed! err=%d\n", ret);
585 if (unlikely(clen > max_zpage_size)) {
587 if (is_partial_io(bvec))
591 handle = zs_malloc(meta->mem_pool, clen);
593 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
599 alloced_pages = zs_get_total_pages(meta->mem_pool);
600 if (zram->limit_pages && alloced_pages > zram->limit_pages) {
601 zs_free(meta->mem_pool, handle);
606 update_used_max(zram, alloced_pages);
608 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
610 if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
611 src = kmap_atomic(page);
612 copy_page(cmem, src);
615 memcpy(cmem, src, clen);
618 zcomp_strm_release(zram->comp, zstrm);
620 zs_unmap_object(meta->mem_pool, handle);
623 * Free memory associated with this sector
624 * before overwriting unused sectors.
626 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
627 zram_free_page(zram, index);
629 meta->table[index].handle = handle;
630 zram_set_obj_size(meta, index, clen);
631 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
634 atomic64_add(clen, &zram->stats.compr_data_size);
635 atomic64_inc(&zram->stats.pages_stored);
638 zcomp_strm_release(zram->comp, zstrm);
639 if (is_partial_io(bvec))
644 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
645 int offset, struct bio *bio)
648 int rw = bio_data_dir(bio);
651 atomic64_inc(&zram->stats.num_reads);
652 ret = zram_bvec_read(zram, bvec, index, offset, bio);
654 atomic64_inc(&zram->stats.num_writes);
655 ret = zram_bvec_write(zram, bvec, index, offset);
660 atomic64_inc(&zram->stats.failed_reads);
662 atomic64_inc(&zram->stats.failed_writes);
669 * zram_bio_discard - handler on discard request
670 * @index: physical block index in PAGE_SIZE units
671 * @offset: byte offset within physical block
673 static void zram_bio_discard(struct zram *zram, u32 index,
674 int offset, struct bio *bio)
676 size_t n = bio->bi_iter.bi_size;
677 struct zram_meta *meta = zram->meta;
680 * zram manages data in physical block size units. Because logical block
681 * size isn't identical with physical block size on some arch, we
682 * could get a discard request pointing to a specific offset within a
683 * certain physical block. Although we can handle this request by
684 * reading that physiclal block and decompressing and partially zeroing
685 * and re-compressing and then re-storing it, this isn't reasonable
686 * because our intent with a discard request is to save memory. So
687 * skipping this logical block is appropriate here.
690 if (n <= (PAGE_SIZE - offset))
693 n -= (PAGE_SIZE - offset);
697 while (n >= PAGE_SIZE) {
698 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
699 zram_free_page(zram, index);
700 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
701 atomic64_inc(&zram->stats.notify_free);
707 static void zram_reset_device(struct zram *zram, bool reset_capacity)
710 struct zram_meta *meta;
712 down_write(&zram->init_lock);
714 zram->limit_pages = 0;
716 if (!init_done(zram)) {
717 up_write(&zram->init_lock);
722 /* Free all pages that are still in this zram device */
723 for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
724 unsigned long handle = meta->table[index].handle;
728 zs_free(meta->mem_pool, handle);
731 zcomp_destroy(zram->comp);
732 zram->max_comp_streams = 1;
734 zram_meta_free(zram->meta);
737 memset(&zram->stats, 0, sizeof(zram->stats));
741 set_capacity(zram->disk, 0);
743 up_write(&zram->init_lock);
746 * Revalidate disk out of the init_lock to avoid lockdep splat.
747 * It's okay because disk's capacity is protected by init_lock
748 * so that revalidate_disk always sees up-to-date capacity.
751 revalidate_disk(zram->disk);
754 static ssize_t disksize_store(struct device *dev,
755 struct device_attribute *attr, const char *buf, size_t len)
759 struct zram_meta *meta;
760 struct zram *zram = dev_to_zram(dev);
763 disksize = memparse(buf, NULL);
767 disksize = PAGE_ALIGN(disksize);
768 meta = zram_meta_alloc(disksize);
772 comp = zcomp_create(zram->compressor, zram->max_comp_streams);
774 pr_info("Cannot initialise %s compressing backend\n",
780 down_write(&zram->init_lock);
781 if (init_done(zram)) {
782 pr_info("Cannot change disksize for initialized device\n");
784 goto out_destroy_comp;
789 zram->disksize = disksize;
790 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
791 up_write(&zram->init_lock);
794 * Revalidate disk out of the init_lock to avoid lockdep splat.
795 * It's okay because disk's capacity is protected by init_lock
796 * so that revalidate_disk always sees up-to-date capacity.
798 revalidate_disk(zram->disk);
803 up_write(&zram->init_lock);
806 zram_meta_free(meta);
810 static ssize_t reset_store(struct device *dev,
811 struct device_attribute *attr, const char *buf, size_t len)
814 unsigned short do_reset;
816 struct block_device *bdev;
818 zram = dev_to_zram(dev);
819 bdev = bdget_disk(zram->disk, 0);
824 /* Do not reset an active device! */
825 if (bdev->bd_holders) {
830 ret = kstrtou16(buf, 10, &do_reset);
839 /* Make sure all pending I/O is finished */
843 zram_reset_device(zram, true);
851 static void __zram_make_request(struct zram *zram, struct bio *bio)
856 struct bvec_iter iter;
858 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
859 offset = (bio->bi_iter.bi_sector &
860 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
862 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
863 zram_bio_discard(zram, index, offset, bio);
868 bio_for_each_segment(bvec, bio, iter) {
869 int max_transfer_size = PAGE_SIZE - offset;
871 if (bvec.bv_len > max_transfer_size) {
873 * zram_bvec_rw() can only make operation on a single
874 * zram page. Split the bio vector.
878 bv.bv_page = bvec.bv_page;
879 bv.bv_len = max_transfer_size;
880 bv.bv_offset = bvec.bv_offset;
882 if (zram_bvec_rw(zram, &bv, index, offset, bio) < 0)
885 bv.bv_len = bvec.bv_len - max_transfer_size;
886 bv.bv_offset += max_transfer_size;
887 if (zram_bvec_rw(zram, &bv, index + 1, 0, bio) < 0)
890 if (zram_bvec_rw(zram, &bvec, index, offset, bio) < 0)
893 update_position(&index, &offset, &bvec);
896 set_bit(BIO_UPTODATE, &bio->bi_flags);
905 * Handler function for all zram I/O requests.
907 static void zram_make_request(struct request_queue *queue, struct bio *bio)
909 struct zram *zram = queue->queuedata;
911 down_read(&zram->init_lock);
912 if (unlikely(!init_done(zram)))
915 if (!valid_io_request(zram, bio)) {
916 atomic64_inc(&zram->stats.invalid_io);
920 __zram_make_request(zram, bio);
921 up_read(&zram->init_lock);
926 up_read(&zram->init_lock);
930 static void zram_slot_free_notify(struct block_device *bdev,
934 struct zram_meta *meta;
936 zram = bdev->bd_disk->private_data;
939 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
940 zram_free_page(zram, index);
941 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
942 atomic64_inc(&zram->stats.notify_free);
945 static const struct block_device_operations zram_devops = {
946 .swap_slot_free_notify = zram_slot_free_notify,
950 static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
951 disksize_show, disksize_store);
952 static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
953 static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
954 static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
955 static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
956 static DEVICE_ATTR(mem_limit, S_IRUGO | S_IWUSR, mem_limit_show,
958 static DEVICE_ATTR(mem_used_max, S_IRUGO | S_IWUSR, mem_used_max_show,
960 static DEVICE_ATTR(max_comp_streams, S_IRUGO | S_IWUSR,
961 max_comp_streams_show, max_comp_streams_store);
962 static DEVICE_ATTR(comp_algorithm, S_IRUGO | S_IWUSR,
963 comp_algorithm_show, comp_algorithm_store);
965 ZRAM_ATTR_RO(num_reads);
966 ZRAM_ATTR_RO(num_writes);
967 ZRAM_ATTR_RO(failed_reads);
968 ZRAM_ATTR_RO(failed_writes);
969 ZRAM_ATTR_RO(invalid_io);
970 ZRAM_ATTR_RO(notify_free);
971 ZRAM_ATTR_RO(zero_pages);
972 ZRAM_ATTR_RO(compr_data_size);
974 static struct attribute *zram_disk_attrs[] = {
975 &dev_attr_disksize.attr,
976 &dev_attr_initstate.attr,
977 &dev_attr_reset.attr,
978 &dev_attr_num_reads.attr,
979 &dev_attr_num_writes.attr,
980 &dev_attr_failed_reads.attr,
981 &dev_attr_failed_writes.attr,
982 &dev_attr_invalid_io.attr,
983 &dev_attr_notify_free.attr,
984 &dev_attr_zero_pages.attr,
985 &dev_attr_orig_data_size.attr,
986 &dev_attr_compr_data_size.attr,
987 &dev_attr_mem_used_total.attr,
988 &dev_attr_mem_limit.attr,
989 &dev_attr_mem_used_max.attr,
990 &dev_attr_max_comp_streams.attr,
991 &dev_attr_comp_algorithm.attr,
995 static struct attribute_group zram_disk_attr_group = {
996 .attrs = zram_disk_attrs,
999 static int create_device(struct zram *zram, int device_id)
1003 init_rwsem(&zram->init_lock);
1005 zram->queue = blk_alloc_queue(GFP_KERNEL);
1007 pr_err("Error allocating disk queue for device %d\n",
1012 blk_queue_make_request(zram->queue, zram_make_request);
1013 zram->queue->queuedata = zram;
1015 /* gendisk structure */
1016 zram->disk = alloc_disk(1);
1018 pr_warn("Error allocating disk structure for device %d\n",
1020 goto out_free_queue;
1023 zram->disk->major = zram_major;
1024 zram->disk->first_minor = device_id;
1025 zram->disk->fops = &zram_devops;
1026 zram->disk->queue = zram->queue;
1027 zram->disk->private_data = zram;
1028 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1030 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1031 set_capacity(zram->disk, 0);
1032 /* zram devices sort of resembles non-rotational disks */
1033 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
1034 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1036 * To ensure that we always get PAGE_SIZE aligned
1037 * and n*PAGE_SIZED sized I/O requests.
1039 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1040 blk_queue_logical_block_size(zram->disk->queue,
1041 ZRAM_LOGICAL_BLOCK_SIZE);
1042 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1043 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1044 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1045 zram->disk->queue->limits.max_discard_sectors = UINT_MAX;
1047 * zram_bio_discard() will clear all logical blocks if logical block
1048 * size is identical with physical block size(PAGE_SIZE). But if it is
1049 * different, we will skip discarding some parts of logical blocks in
1050 * the part of the request range which isn't aligned to physical block
1051 * size. So we can't ensure that all discarded logical blocks are
1054 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1055 zram->disk->queue->limits.discard_zeroes_data = 1;
1057 zram->disk->queue->limits.discard_zeroes_data = 0;
1058 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
1060 add_disk(zram->disk);
1062 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
1063 &zram_disk_attr_group);
1065 pr_warn("Error creating sysfs group");
1068 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1070 zram->max_comp_streams = 1;
1074 del_gendisk(zram->disk);
1075 put_disk(zram->disk);
1077 blk_cleanup_queue(zram->queue);
1082 static void destroy_device(struct zram *zram)
1084 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
1085 &zram_disk_attr_group);
1087 del_gendisk(zram->disk);
1088 put_disk(zram->disk);
1090 blk_cleanup_queue(zram->queue);
1093 static int __init zram_init(void)
1097 if (num_devices > max_num_devices) {
1098 pr_warn("Invalid value for num_devices: %u\n",
1104 zram_major = register_blkdev(0, "zram");
1105 if (zram_major <= 0) {
1106 pr_warn("Unable to get major number\n");
1111 /* Allocate the device array and initialize each one */
1112 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
1113 if (!zram_devices) {
1118 for (dev_id = 0; dev_id < num_devices; dev_id++) {
1119 ret = create_device(&zram_devices[dev_id], dev_id);
1124 pr_info("Created %u device(s) ...\n", num_devices);
1130 destroy_device(&zram_devices[--dev_id]);
1131 kfree(zram_devices);
1133 unregister_blkdev(zram_major, "zram");
1138 static void __exit zram_exit(void)
1143 for (i = 0; i < num_devices; i++) {
1144 zram = &zram_devices[i];
1146 destroy_device(zram);
1148 * Shouldn't access zram->disk after destroy_device
1149 * because destroy_device already released zram->disk.
1151 zram_reset_device(zram, false);
1154 unregister_blkdev(zram_major, "zram");
1156 kfree(zram_devices);
1157 pr_debug("Cleanup done!\n");
1160 module_init(zram_init);
1161 module_exit(zram_exit);
1163 module_param(num_devices, uint, 0);
1164 MODULE_PARM_DESC(num_devices, "Number of zram devices");
1166 MODULE_LICENSE("Dual BSD/GPL");
1167 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1168 MODULE_DESCRIPTION("Compressed RAM Block Device");