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 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 DEVICE_ATTR_RO(name);
56 static inline bool init_done(struct zram *zram)
58 return zram->disksize;
61 static inline struct zram *dev_to_zram(struct device *dev)
63 return (struct zram *)dev_to_disk(dev)->private_data;
66 static ssize_t disksize_show(struct device *dev,
67 struct device_attribute *attr, char *buf)
69 struct zram *zram = dev_to_zram(dev);
71 return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize);
74 static ssize_t initstate_show(struct device *dev,
75 struct device_attribute *attr, char *buf)
78 struct zram *zram = dev_to_zram(dev);
80 down_read(&zram->init_lock);
81 val = init_done(zram);
82 up_read(&zram->init_lock);
84 return scnprintf(buf, PAGE_SIZE, "%u\n", val);
87 static ssize_t orig_data_size_show(struct device *dev,
88 struct device_attribute *attr, char *buf)
90 struct zram *zram = dev_to_zram(dev);
92 return scnprintf(buf, PAGE_SIZE, "%llu\n",
93 (u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
96 static ssize_t mem_used_total_show(struct device *dev,
97 struct device_attribute *attr, char *buf)
100 struct zram *zram = dev_to_zram(dev);
102 down_read(&zram->init_lock);
103 if (init_done(zram)) {
104 struct zram_meta *meta = zram->meta;
105 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);
177 err = kstrtoul(buf, 10, &val);
181 down_read(&zram->init_lock);
182 if (init_done(zram)) {
183 struct zram_meta *meta = zram->meta;
184 atomic_long_set(&zram->stats.max_used_pages,
185 zs_get_total_pages(meta->mem_pool));
187 up_read(&zram->init_lock);
192 static ssize_t max_comp_streams_store(struct device *dev,
193 struct device_attribute *attr, const char *buf, size_t len)
196 struct zram *zram = dev_to_zram(dev);
199 ret = kstrtoint(buf, 0, &num);
205 down_write(&zram->init_lock);
206 if (init_done(zram)) {
207 if (!zcomp_set_max_streams(zram->comp, num)) {
208 pr_info("Cannot change max compression streams\n");
214 zram->max_comp_streams = num;
217 up_write(&zram->init_lock);
221 static ssize_t comp_algorithm_show(struct device *dev,
222 struct device_attribute *attr, char *buf)
225 struct zram *zram = dev_to_zram(dev);
227 down_read(&zram->init_lock);
228 sz = zcomp_available_show(zram->compressor, buf);
229 up_read(&zram->init_lock);
234 static ssize_t comp_algorithm_store(struct device *dev,
235 struct device_attribute *attr, const char *buf, size_t len)
237 struct zram *zram = dev_to_zram(dev);
238 down_write(&zram->init_lock);
239 if (init_done(zram)) {
240 up_write(&zram->init_lock);
241 pr_info("Can't change algorithm for initialized device\n");
244 strlcpy(zram->compressor, buf, sizeof(zram->compressor));
245 up_write(&zram->init_lock);
249 /* flag operations needs meta->tb_lock */
250 static int zram_test_flag(struct zram_meta *meta, u32 index,
251 enum zram_pageflags flag)
253 return meta->table[index].value & BIT(flag);
256 static void zram_set_flag(struct zram_meta *meta, u32 index,
257 enum zram_pageflags flag)
259 meta->table[index].value |= BIT(flag);
262 static void zram_clear_flag(struct zram_meta *meta, u32 index,
263 enum zram_pageflags flag)
265 meta->table[index].value &= ~BIT(flag);
268 static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
270 return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
273 static void zram_set_obj_size(struct zram_meta *meta,
274 u32 index, size_t size)
276 unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT;
278 meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
281 static inline int is_partial_io(struct bio_vec *bvec)
283 return bvec->bv_len != PAGE_SIZE;
287 * Check if request is within bounds and aligned on zram logical blocks.
289 static inline int valid_io_request(struct zram *zram,
290 sector_t start, unsigned int size)
294 /* unaligned request */
295 if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
297 if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
300 end = start + (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, u64 disksize)
312 size_t num_pages = disksize >> PAGE_SHIFT;
315 /* Free all pages that are still in this zram device */
316 for (index = 0; index < num_pages; index++) {
317 unsigned long handle = meta->table[index].handle;
322 zs_free(meta->mem_pool, handle);
325 zs_destroy_pool(meta->mem_pool);
330 static struct zram_meta *zram_meta_alloc(int device_id, u64 disksize)
334 struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
339 num_pages = disksize >> PAGE_SHIFT;
340 meta->table = vzalloc(num_pages * sizeof(*meta->table));
342 pr_err("Error allocating zram address table\n");
346 snprintf(pool_name, sizeof(pool_name), "zram%d", device_id);
347 meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO | __GFP_HIGHMEM);
348 if (!meta->mem_pool) {
349 pr_err("Error creating memory pool\n");
361 static inline bool zram_meta_get(struct zram *zram)
363 if (atomic_inc_not_zero(&zram->refcount))
368 static inline void zram_meta_put(struct zram *zram)
370 atomic_dec(&zram->refcount);
373 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
375 if (*offset + bvec->bv_len >= PAGE_SIZE)
377 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
380 static int page_zero_filled(void *ptr)
385 page = (unsigned long *)ptr;
387 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
395 static void handle_zero_page(struct bio_vec *bvec)
397 struct page *page = bvec->bv_page;
400 user_mem = kmap_atomic(page);
401 if (is_partial_io(bvec))
402 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
404 clear_page(user_mem);
405 kunmap_atomic(user_mem);
407 flush_dcache_page(page);
412 * To protect concurrent access to the same index entry,
413 * caller should hold this table index entry's bit_spinlock to
414 * indicate this index entry is accessing.
416 static void zram_free_page(struct zram *zram, size_t index)
418 struct zram_meta *meta = zram->meta;
419 unsigned long handle = meta->table[index].handle;
421 if (unlikely(!handle)) {
423 * No memory is allocated for zero filled pages.
424 * Simply clear zero page flag.
426 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
427 zram_clear_flag(meta, index, ZRAM_ZERO);
428 atomic64_dec(&zram->stats.zero_pages);
433 zs_free(meta->mem_pool, handle);
435 atomic64_sub(zram_get_obj_size(meta, index),
436 &zram->stats.compr_data_size);
437 atomic64_dec(&zram->stats.pages_stored);
439 meta->table[index].handle = 0;
440 zram_set_obj_size(meta, index, 0);
443 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
447 struct zram_meta *meta = zram->meta;
448 unsigned long handle;
451 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
452 handle = meta->table[index].handle;
453 size = zram_get_obj_size(meta, index);
455 if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
456 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
461 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
462 if (size == PAGE_SIZE)
463 copy_page(mem, cmem);
465 ret = zcomp_decompress(zram->comp, cmem, size, mem);
466 zs_unmap_object(meta->mem_pool, handle);
467 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
469 /* Should NEVER happen. Return bio error if it does. */
471 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
478 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
479 u32 index, int offset)
483 unsigned char *user_mem, *uncmem = NULL;
484 struct zram_meta *meta = zram->meta;
485 page = bvec->bv_page;
487 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
488 if (unlikely(!meta->table[index].handle) ||
489 zram_test_flag(meta, index, ZRAM_ZERO)) {
490 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
491 handle_zero_page(bvec);
494 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
496 if (is_partial_io(bvec))
497 /* Use a temporary buffer to decompress the page */
498 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
500 user_mem = kmap_atomic(page);
501 if (!is_partial_io(bvec))
505 pr_info("Unable to allocate temp memory\n");
510 ret = zram_decompress_page(zram, uncmem, index);
511 /* Should NEVER happen. Return bio error if it does. */
515 if (is_partial_io(bvec))
516 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
519 flush_dcache_page(page);
522 kunmap_atomic(user_mem);
523 if (is_partial_io(bvec))
528 static inline void update_used_max(struct zram *zram,
529 const unsigned long pages)
531 int old_max, cur_max;
533 old_max = atomic_long_read(&zram->stats.max_used_pages);
538 old_max = atomic_long_cmpxchg(
539 &zram->stats.max_used_pages, cur_max, pages);
540 } while (old_max != cur_max);
543 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
548 unsigned long handle;
550 unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
551 struct zram_meta *meta = zram->meta;
552 struct zcomp_strm *zstrm;
554 unsigned long alloced_pages;
556 page = bvec->bv_page;
557 if (is_partial_io(bvec)) {
559 * This is a partial IO. We need to read the full page
560 * before to write the changes.
562 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
567 ret = zram_decompress_page(zram, uncmem, index);
572 zstrm = zcomp_strm_find(zram->comp);
574 user_mem = kmap_atomic(page);
576 if (is_partial_io(bvec)) {
577 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
579 kunmap_atomic(user_mem);
585 if (page_zero_filled(uncmem)) {
587 kunmap_atomic(user_mem);
588 /* Free memory associated with this sector now. */
589 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
590 zram_free_page(zram, index);
591 zram_set_flag(meta, index, ZRAM_ZERO);
592 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
594 atomic64_inc(&zram->stats.zero_pages);
599 ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen);
600 if (!is_partial_io(bvec)) {
601 kunmap_atomic(user_mem);
607 pr_err("Compression failed! err=%d\n", ret);
611 if (unlikely(clen > max_zpage_size)) {
613 if (is_partial_io(bvec))
617 handle = zs_malloc(meta->mem_pool, clen);
619 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
625 alloced_pages = zs_get_total_pages(meta->mem_pool);
626 if (zram->limit_pages && alloced_pages > zram->limit_pages) {
627 zs_free(meta->mem_pool, handle);
632 update_used_max(zram, alloced_pages);
634 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
636 if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
637 src = kmap_atomic(page);
638 copy_page(cmem, src);
641 memcpy(cmem, src, clen);
644 zcomp_strm_release(zram->comp, zstrm);
646 zs_unmap_object(meta->mem_pool, handle);
649 * Free memory associated with this sector
650 * before overwriting unused sectors.
652 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
653 zram_free_page(zram, index);
655 meta->table[index].handle = handle;
656 zram_set_obj_size(meta, index, clen);
657 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
660 atomic64_add(clen, &zram->stats.compr_data_size);
661 atomic64_inc(&zram->stats.pages_stored);
664 zcomp_strm_release(zram->comp, zstrm);
665 if (is_partial_io(bvec))
670 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
676 atomic64_inc(&zram->stats.num_reads);
677 ret = zram_bvec_read(zram, bvec, index, offset);
679 atomic64_inc(&zram->stats.num_writes);
680 ret = zram_bvec_write(zram, bvec, index, offset);
685 atomic64_inc(&zram->stats.failed_reads);
687 atomic64_inc(&zram->stats.failed_writes);
694 * zram_bio_discard - handler on discard request
695 * @index: physical block index in PAGE_SIZE units
696 * @offset: byte offset within physical block
698 static void zram_bio_discard(struct zram *zram, u32 index,
699 int offset, struct bio *bio)
701 size_t n = bio->bi_iter.bi_size;
702 struct zram_meta *meta = zram->meta;
705 * zram manages data in physical block size units. Because logical block
706 * size isn't identical with physical block size on some arch, we
707 * could get a discard request pointing to a specific offset within a
708 * certain physical block. Although we can handle this request by
709 * reading that physiclal block and decompressing and partially zeroing
710 * and re-compressing and then re-storing it, this isn't reasonable
711 * because our intent with a discard request is to save memory. So
712 * skipping this logical block is appropriate here.
715 if (n <= (PAGE_SIZE - offset))
718 n -= (PAGE_SIZE - offset);
722 while (n >= PAGE_SIZE) {
723 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
724 zram_free_page(zram, index);
725 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
726 atomic64_inc(&zram->stats.notify_free);
732 static void zram_reset_device(struct zram *zram)
734 struct zram_meta *meta;
738 down_write(&zram->init_lock);
740 zram->limit_pages = 0;
742 if (!init_done(zram)) {
743 up_write(&zram->init_lock);
749 disksize = zram->disksize;
751 * Refcount will go down to 0 eventually and r/w handler
752 * cannot handle further I/O so it will bail out by
753 * check zram_meta_get.
757 * We want to free zram_meta in process context to avoid
758 * deadlock between reclaim path and any other locks.
760 wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);
763 memset(&zram->stats, 0, sizeof(zram->stats));
765 zram->max_comp_streams = 1;
766 set_capacity(zram->disk, 0);
768 up_write(&zram->init_lock);
769 /* I/O operation under all of CPU are done so let's free */
770 zram_meta_free(meta, disksize);
774 static ssize_t disksize_store(struct device *dev,
775 struct device_attribute *attr, const char *buf, size_t len)
779 struct zram_meta *meta;
780 struct zram *zram = dev_to_zram(dev);
783 disksize = memparse(buf, NULL);
787 disksize = PAGE_ALIGN(disksize);
788 meta = zram_meta_alloc(zram->disk->first_minor, disksize);
792 comp = zcomp_create(zram->compressor, zram->max_comp_streams);
794 pr_info("Cannot initialise %s compressing backend\n",
800 down_write(&zram->init_lock);
801 if (init_done(zram)) {
802 pr_info("Cannot change disksize for initialized device\n");
804 goto out_destroy_comp;
807 init_waitqueue_head(&zram->io_done);
808 atomic_set(&zram->refcount, 1);
811 zram->disksize = disksize;
812 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
813 up_write(&zram->init_lock);
816 * Revalidate disk out of the init_lock to avoid lockdep splat.
817 * It's okay because disk's capacity is protected by init_lock
818 * so that revalidate_disk always sees up-to-date capacity.
820 revalidate_disk(zram->disk);
825 up_write(&zram->init_lock);
828 zram_meta_free(meta, disksize);
832 static ssize_t reset_store(struct device *dev,
833 struct device_attribute *attr, const char *buf, size_t len)
836 unsigned short do_reset;
838 struct block_device *bdev;
840 zram = dev_to_zram(dev);
841 bdev = bdget_disk(zram->disk, 0);
846 mutex_lock(&bdev->bd_mutex);
847 /* Do not reset an active device! */
848 if (bdev->bd_openers) {
853 ret = kstrtou16(buf, 10, &do_reset);
862 /* Make sure all pending I/O is finished */
864 zram_reset_device(zram);
866 mutex_unlock(&bdev->bd_mutex);
867 revalidate_disk(zram->disk);
873 mutex_unlock(&bdev->bd_mutex);
878 static void __zram_make_request(struct zram *zram, struct bio *bio)
883 struct bvec_iter iter;
885 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
886 offset = (bio->bi_iter.bi_sector &
887 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
889 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
890 zram_bio_discard(zram, index, offset, bio);
895 rw = bio_data_dir(bio);
896 bio_for_each_segment(bvec, bio, iter) {
897 int max_transfer_size = PAGE_SIZE - offset;
899 if (bvec.bv_len > max_transfer_size) {
901 * zram_bvec_rw() can only make operation on a single
902 * zram page. Split the bio vector.
906 bv.bv_page = bvec.bv_page;
907 bv.bv_len = max_transfer_size;
908 bv.bv_offset = bvec.bv_offset;
910 if (zram_bvec_rw(zram, &bv, index, offset, rw) < 0)
913 bv.bv_len = bvec.bv_len - max_transfer_size;
914 bv.bv_offset += max_transfer_size;
915 if (zram_bvec_rw(zram, &bv, index + 1, 0, rw) < 0)
918 if (zram_bvec_rw(zram, &bvec, index, offset, rw) < 0)
921 update_position(&index, &offset, &bvec);
924 set_bit(BIO_UPTODATE, &bio->bi_flags);
933 * Handler function for all zram I/O requests.
935 static void zram_make_request(struct request_queue *queue, struct bio *bio)
937 struct zram *zram = queue->queuedata;
939 if (unlikely(!zram_meta_get(zram)))
942 if (!valid_io_request(zram, bio->bi_iter.bi_sector,
943 bio->bi_iter.bi_size)) {
944 atomic64_inc(&zram->stats.invalid_io);
948 __zram_make_request(zram, bio);
957 static void zram_slot_free_notify(struct block_device *bdev,
961 struct zram_meta *meta;
963 zram = bdev->bd_disk->private_data;
966 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
967 zram_free_page(zram, index);
968 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
969 atomic64_inc(&zram->stats.notify_free);
972 static int zram_rw_page(struct block_device *bdev, sector_t sector,
973 struct page *page, int rw)
975 int offset, err = -EIO;
980 zram = bdev->bd_disk->private_data;
981 if (unlikely(!zram_meta_get(zram)))
984 if (!valid_io_request(zram, sector, PAGE_SIZE)) {
985 atomic64_inc(&zram->stats.invalid_io);
990 index = sector >> SECTORS_PER_PAGE_SHIFT;
991 offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT;
994 bv.bv_len = PAGE_SIZE;
997 err = zram_bvec_rw(zram, &bv, index, offset, rw);
1002 * If I/O fails, just return error(ie, non-zero) without
1003 * calling page_endio.
1004 * It causes resubmit the I/O with bio request by upper functions
1005 * of rw_page(e.g., swap_readpage, __swap_writepage) and
1006 * bio->bi_end_io does things to handle the error
1007 * (e.g., SetPageError, set_page_dirty and extra works).
1010 page_endio(page, rw, 0);
1014 static const struct block_device_operations zram_devops = {
1015 .swap_slot_free_notify = zram_slot_free_notify,
1016 .rw_page = zram_rw_page,
1017 .owner = THIS_MODULE
1020 static DEVICE_ATTR_RW(disksize);
1021 static DEVICE_ATTR_RO(initstate);
1022 static DEVICE_ATTR_WO(reset);
1023 static DEVICE_ATTR_RO(orig_data_size);
1024 static DEVICE_ATTR_RO(mem_used_total);
1025 static DEVICE_ATTR_RW(mem_limit);
1026 static DEVICE_ATTR_RW(mem_used_max);
1027 static DEVICE_ATTR_RW(max_comp_streams);
1028 static DEVICE_ATTR_RW(comp_algorithm);
1030 ZRAM_ATTR_RO(num_reads);
1031 ZRAM_ATTR_RO(num_writes);
1032 ZRAM_ATTR_RO(failed_reads);
1033 ZRAM_ATTR_RO(failed_writes);
1034 ZRAM_ATTR_RO(invalid_io);
1035 ZRAM_ATTR_RO(notify_free);
1036 ZRAM_ATTR_RO(zero_pages);
1037 ZRAM_ATTR_RO(compr_data_size);
1039 static struct attribute *zram_disk_attrs[] = {
1040 &dev_attr_disksize.attr,
1041 &dev_attr_initstate.attr,
1042 &dev_attr_reset.attr,
1043 &dev_attr_num_reads.attr,
1044 &dev_attr_num_writes.attr,
1045 &dev_attr_failed_reads.attr,
1046 &dev_attr_failed_writes.attr,
1047 &dev_attr_invalid_io.attr,
1048 &dev_attr_notify_free.attr,
1049 &dev_attr_zero_pages.attr,
1050 &dev_attr_orig_data_size.attr,
1051 &dev_attr_compr_data_size.attr,
1052 &dev_attr_mem_used_total.attr,
1053 &dev_attr_mem_limit.attr,
1054 &dev_attr_mem_used_max.attr,
1055 &dev_attr_max_comp_streams.attr,
1056 &dev_attr_comp_algorithm.attr,
1060 static struct attribute_group zram_disk_attr_group = {
1061 .attrs = zram_disk_attrs,
1064 static int create_device(struct zram *zram, int device_id)
1066 struct request_queue *queue;
1069 init_rwsem(&zram->init_lock);
1071 queue = blk_alloc_queue(GFP_KERNEL);
1073 pr_err("Error allocating disk queue for device %d\n",
1078 blk_queue_make_request(queue, zram_make_request);
1080 /* gendisk structure */
1081 zram->disk = alloc_disk(1);
1083 pr_warn("Error allocating disk structure for device %d\n",
1085 goto out_free_queue;
1088 zram->disk->major = zram_major;
1089 zram->disk->first_minor = device_id;
1090 zram->disk->fops = &zram_devops;
1091 zram->disk->queue = queue;
1092 zram->disk->queue->queuedata = zram;
1093 zram->disk->private_data = zram;
1094 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1096 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1097 set_capacity(zram->disk, 0);
1098 /* zram devices sort of resembles non-rotational disks */
1099 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
1100 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1102 * To ensure that we always get PAGE_SIZE aligned
1103 * and n*PAGE_SIZED sized I/O requests.
1105 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1106 blk_queue_logical_block_size(zram->disk->queue,
1107 ZRAM_LOGICAL_BLOCK_SIZE);
1108 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1109 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1110 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1111 zram->disk->queue->limits.max_discard_sectors = UINT_MAX;
1113 * zram_bio_discard() will clear all logical blocks if logical block
1114 * size is identical with physical block size(PAGE_SIZE). But if it is
1115 * different, we will skip discarding some parts of logical blocks in
1116 * the part of the request range which isn't aligned to physical block
1117 * size. So we can't ensure that all discarded logical blocks are
1120 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1121 zram->disk->queue->limits.discard_zeroes_data = 1;
1123 zram->disk->queue->limits.discard_zeroes_data = 0;
1124 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
1126 add_disk(zram->disk);
1128 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
1129 &zram_disk_attr_group);
1131 pr_warn("Error creating sysfs group");
1134 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1136 zram->max_comp_streams = 1;
1140 del_gendisk(zram->disk);
1141 put_disk(zram->disk);
1143 blk_cleanup_queue(queue);
1148 static void destroy_devices(unsigned int nr)
1153 for (i = 0; i < nr; i++) {
1154 zram = &zram_devices[i];
1156 * Remove sysfs first, so no one will perform a disksize
1157 * store while we destroy the devices
1159 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
1160 &zram_disk_attr_group);
1162 zram_reset_device(zram);
1164 blk_cleanup_queue(zram->disk->queue);
1165 del_gendisk(zram->disk);
1166 put_disk(zram->disk);
1169 kfree(zram_devices);
1170 unregister_blkdev(zram_major, "zram");
1171 pr_info("Destroyed %u device(s)\n", nr);
1174 static int __init zram_init(void)
1178 if (num_devices > max_num_devices) {
1179 pr_warn("Invalid value for num_devices: %u\n",
1184 zram_major = register_blkdev(0, "zram");
1185 if (zram_major <= 0) {
1186 pr_warn("Unable to get major number\n");
1190 /* Allocate the device array and initialize each one */
1191 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
1192 if (!zram_devices) {
1193 unregister_blkdev(zram_major, "zram");
1197 for (dev_id = 0; dev_id < num_devices; dev_id++) {
1198 ret = create_device(&zram_devices[dev_id], dev_id);
1203 pr_info("Created %u device(s)\n", num_devices);
1207 destroy_devices(dev_id);
1211 static void __exit zram_exit(void)
1213 destroy_devices(num_devices);
1216 module_init(zram_init);
1217 module_exit(zram_exit);
1219 module_param(num_devices, uint, 0);
1220 MODULE_PARM_DESC(num_devices, "Number of zram devices");
1222 MODULE_LICENSE("Dual BSD/GPL");
1223 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1224 MODULE_DESCRIPTION("Compressed RAM Block Device");