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 static inline void deprecated_attr_warn(const char *name)
48 pr_warn_once("%d (%s) Attribute %s (and others) will be removed. %s\n",
52 "See zram documentation.");
55 #define ZRAM_ATTR_RO(name) \
56 static ssize_t name##_show(struct device *d, \
57 struct device_attribute *attr, char *b) \
59 struct zram *zram = dev_to_zram(d); \
61 deprecated_attr_warn(__stringify(name)); \
62 return scnprintf(b, PAGE_SIZE, "%llu\n", \
63 (u64)atomic64_read(&zram->stats.name)); \
65 static DEVICE_ATTR_RO(name);
67 static inline bool init_done(struct zram *zram)
69 return zram->disksize;
72 static inline struct zram *dev_to_zram(struct device *dev)
74 return (struct zram *)dev_to_disk(dev)->private_data;
77 static ssize_t compact_store(struct device *dev,
78 struct device_attribute *attr, const char *buf, size_t len)
80 unsigned long nr_migrated;
81 struct zram *zram = dev_to_zram(dev);
82 struct zram_meta *meta;
84 down_read(&zram->init_lock);
85 if (!init_done(zram)) {
86 up_read(&zram->init_lock);
91 nr_migrated = zs_compact(meta->mem_pool);
92 atomic64_add(nr_migrated, &zram->stats.num_migrated);
93 up_read(&zram->init_lock);
98 static ssize_t disksize_show(struct device *dev,
99 struct device_attribute *attr, char *buf)
101 struct zram *zram = dev_to_zram(dev);
103 return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize);
106 static ssize_t initstate_show(struct device *dev,
107 struct device_attribute *attr, char *buf)
110 struct zram *zram = dev_to_zram(dev);
112 down_read(&zram->init_lock);
113 val = init_done(zram);
114 up_read(&zram->init_lock);
116 return scnprintf(buf, PAGE_SIZE, "%u\n", val);
119 static ssize_t orig_data_size_show(struct device *dev,
120 struct device_attribute *attr, char *buf)
122 struct zram *zram = dev_to_zram(dev);
124 deprecated_attr_warn("orig_data_size");
125 return scnprintf(buf, PAGE_SIZE, "%llu\n",
126 (u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
129 static ssize_t mem_used_total_show(struct device *dev,
130 struct device_attribute *attr, char *buf)
133 struct zram *zram = dev_to_zram(dev);
135 deprecated_attr_warn("mem_used_total");
136 down_read(&zram->init_lock);
137 if (init_done(zram)) {
138 struct zram_meta *meta = zram->meta;
139 val = zs_get_total_pages(meta->mem_pool);
141 up_read(&zram->init_lock);
143 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
146 static ssize_t max_comp_streams_show(struct device *dev,
147 struct device_attribute *attr, char *buf)
150 struct zram *zram = dev_to_zram(dev);
152 down_read(&zram->init_lock);
153 val = zram->max_comp_streams;
154 up_read(&zram->init_lock);
156 return scnprintf(buf, PAGE_SIZE, "%d\n", val);
159 static ssize_t mem_limit_show(struct device *dev,
160 struct device_attribute *attr, char *buf)
163 struct zram *zram = dev_to_zram(dev);
165 deprecated_attr_warn("mem_limit");
166 down_read(&zram->init_lock);
167 val = zram->limit_pages;
168 up_read(&zram->init_lock);
170 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
173 static ssize_t mem_limit_store(struct device *dev,
174 struct device_attribute *attr, const char *buf, size_t len)
178 struct zram *zram = dev_to_zram(dev);
180 limit = memparse(buf, &tmp);
181 if (buf == tmp) /* no chars parsed, invalid input */
184 down_write(&zram->init_lock);
185 zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
186 up_write(&zram->init_lock);
191 static ssize_t mem_used_max_show(struct device *dev,
192 struct device_attribute *attr, char *buf)
195 struct zram *zram = dev_to_zram(dev);
197 deprecated_attr_warn("mem_used_max");
198 down_read(&zram->init_lock);
200 val = atomic_long_read(&zram->stats.max_used_pages);
201 up_read(&zram->init_lock);
203 return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
206 static ssize_t mem_used_max_store(struct device *dev,
207 struct device_attribute *attr, const char *buf, size_t len)
211 struct zram *zram = dev_to_zram(dev);
213 err = kstrtoul(buf, 10, &val);
217 down_read(&zram->init_lock);
218 if (init_done(zram)) {
219 struct zram_meta *meta = zram->meta;
220 atomic_long_set(&zram->stats.max_used_pages,
221 zs_get_total_pages(meta->mem_pool));
223 up_read(&zram->init_lock);
228 static ssize_t max_comp_streams_store(struct device *dev,
229 struct device_attribute *attr, const char *buf, size_t len)
232 struct zram *zram = dev_to_zram(dev);
235 ret = kstrtoint(buf, 0, &num);
241 down_write(&zram->init_lock);
242 if (init_done(zram)) {
243 if (!zcomp_set_max_streams(zram->comp, num)) {
244 pr_info("Cannot change max compression streams\n");
250 zram->max_comp_streams = num;
253 up_write(&zram->init_lock);
257 static ssize_t comp_algorithm_show(struct device *dev,
258 struct device_attribute *attr, char *buf)
261 struct zram *zram = dev_to_zram(dev);
263 down_read(&zram->init_lock);
264 sz = zcomp_available_show(zram->compressor, buf);
265 up_read(&zram->init_lock);
270 static ssize_t comp_algorithm_store(struct device *dev,
271 struct device_attribute *attr, const char *buf, size_t len)
273 struct zram *zram = dev_to_zram(dev);
274 down_write(&zram->init_lock);
275 if (init_done(zram)) {
276 up_write(&zram->init_lock);
277 pr_info("Can't change algorithm for initialized device\n");
280 strlcpy(zram->compressor, buf, sizeof(zram->compressor));
281 up_write(&zram->init_lock);
285 /* flag operations needs meta->tb_lock */
286 static int zram_test_flag(struct zram_meta *meta, u32 index,
287 enum zram_pageflags flag)
289 return meta->table[index].value & BIT(flag);
292 static void zram_set_flag(struct zram_meta *meta, u32 index,
293 enum zram_pageflags flag)
295 meta->table[index].value |= BIT(flag);
298 static void zram_clear_flag(struct zram_meta *meta, u32 index,
299 enum zram_pageflags flag)
301 meta->table[index].value &= ~BIT(flag);
304 static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
306 return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
309 static void zram_set_obj_size(struct zram_meta *meta,
310 u32 index, size_t size)
312 unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT;
314 meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
317 static inline int is_partial_io(struct bio_vec *bvec)
319 return bvec->bv_len != PAGE_SIZE;
323 * Check if request is within bounds and aligned on zram logical blocks.
325 static inline int valid_io_request(struct zram *zram,
326 sector_t start, unsigned int size)
330 /* unaligned request */
331 if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
333 if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
336 end = start + (size >> SECTOR_SHIFT);
337 bound = zram->disksize >> SECTOR_SHIFT;
338 /* out of range range */
339 if (unlikely(start >= bound || end > bound || start > end))
342 /* I/O request is valid */
346 static void zram_meta_free(struct zram_meta *meta, u64 disksize)
348 size_t num_pages = disksize >> PAGE_SHIFT;
351 /* Free all pages that are still in this zram device */
352 for (index = 0; index < num_pages; index++) {
353 unsigned long handle = meta->table[index].handle;
358 zs_free(meta->mem_pool, handle);
361 zs_destroy_pool(meta->mem_pool);
366 static struct zram_meta *zram_meta_alloc(int device_id, u64 disksize)
370 struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
375 num_pages = disksize >> PAGE_SHIFT;
376 meta->table = vzalloc(num_pages * sizeof(*meta->table));
378 pr_err("Error allocating zram address table\n");
382 snprintf(pool_name, sizeof(pool_name), "zram%d", device_id);
383 meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO | __GFP_HIGHMEM);
384 if (!meta->mem_pool) {
385 pr_err("Error creating memory pool\n");
397 static inline bool zram_meta_get(struct zram *zram)
399 if (atomic_inc_not_zero(&zram->refcount))
404 static inline void zram_meta_put(struct zram *zram)
406 atomic_dec(&zram->refcount);
409 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
411 if (*offset + bvec->bv_len >= PAGE_SIZE)
413 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
416 static int page_zero_filled(void *ptr)
421 page = (unsigned long *)ptr;
423 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
431 static void handle_zero_page(struct bio_vec *bvec)
433 struct page *page = bvec->bv_page;
436 user_mem = kmap_atomic(page);
437 if (is_partial_io(bvec))
438 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
440 clear_page(user_mem);
441 kunmap_atomic(user_mem);
443 flush_dcache_page(page);
448 * To protect concurrent access to the same index entry,
449 * caller should hold this table index entry's bit_spinlock to
450 * indicate this index entry is accessing.
452 static void zram_free_page(struct zram *zram, size_t index)
454 struct zram_meta *meta = zram->meta;
455 unsigned long handle = meta->table[index].handle;
457 if (unlikely(!handle)) {
459 * No memory is allocated for zero filled pages.
460 * Simply clear zero page flag.
462 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
463 zram_clear_flag(meta, index, ZRAM_ZERO);
464 atomic64_dec(&zram->stats.zero_pages);
469 zs_free(meta->mem_pool, handle);
471 atomic64_sub(zram_get_obj_size(meta, index),
472 &zram->stats.compr_data_size);
473 atomic64_dec(&zram->stats.pages_stored);
475 meta->table[index].handle = 0;
476 zram_set_obj_size(meta, index, 0);
479 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
483 struct zram_meta *meta = zram->meta;
484 unsigned long handle;
487 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
488 handle = meta->table[index].handle;
489 size = zram_get_obj_size(meta, index);
491 if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
492 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
497 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
498 if (size == PAGE_SIZE)
499 copy_page(mem, cmem);
501 ret = zcomp_decompress(zram->comp, cmem, size, mem);
502 zs_unmap_object(meta->mem_pool, handle);
503 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
505 /* Should NEVER happen. Return bio error if it does. */
507 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
514 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
515 u32 index, int offset)
519 unsigned char *user_mem, *uncmem = NULL;
520 struct zram_meta *meta = zram->meta;
521 page = bvec->bv_page;
523 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
524 if (unlikely(!meta->table[index].handle) ||
525 zram_test_flag(meta, index, ZRAM_ZERO)) {
526 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
527 handle_zero_page(bvec);
530 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
532 if (is_partial_io(bvec))
533 /* Use a temporary buffer to decompress the page */
534 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
536 user_mem = kmap_atomic(page);
537 if (!is_partial_io(bvec))
541 pr_info("Unable to allocate temp memory\n");
546 ret = zram_decompress_page(zram, uncmem, index);
547 /* Should NEVER happen. Return bio error if it does. */
551 if (is_partial_io(bvec))
552 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
555 flush_dcache_page(page);
558 kunmap_atomic(user_mem);
559 if (is_partial_io(bvec))
564 static inline void update_used_max(struct zram *zram,
565 const unsigned long pages)
567 unsigned long old_max, cur_max;
569 old_max = atomic_long_read(&zram->stats.max_used_pages);
574 old_max = atomic_long_cmpxchg(
575 &zram->stats.max_used_pages, cur_max, pages);
576 } while (old_max != cur_max);
579 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
584 unsigned long handle;
586 unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
587 struct zram_meta *meta = zram->meta;
588 struct zcomp_strm *zstrm;
590 unsigned long alloced_pages;
592 page = bvec->bv_page;
593 if (is_partial_io(bvec)) {
595 * This is a partial IO. We need to read the full page
596 * before to write the changes.
598 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
603 ret = zram_decompress_page(zram, uncmem, index);
608 zstrm = zcomp_strm_find(zram->comp);
610 user_mem = kmap_atomic(page);
612 if (is_partial_io(bvec)) {
613 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
615 kunmap_atomic(user_mem);
621 if (page_zero_filled(uncmem)) {
623 kunmap_atomic(user_mem);
624 /* Free memory associated with this sector now. */
625 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
626 zram_free_page(zram, index);
627 zram_set_flag(meta, index, ZRAM_ZERO);
628 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
630 atomic64_inc(&zram->stats.zero_pages);
635 ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen);
636 if (!is_partial_io(bvec)) {
637 kunmap_atomic(user_mem);
643 pr_err("Compression failed! err=%d\n", ret);
647 if (unlikely(clen > max_zpage_size)) {
649 if (is_partial_io(bvec))
653 handle = zs_malloc(meta->mem_pool, clen);
655 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
661 alloced_pages = zs_get_total_pages(meta->mem_pool);
662 if (zram->limit_pages && alloced_pages > zram->limit_pages) {
663 zs_free(meta->mem_pool, handle);
668 update_used_max(zram, alloced_pages);
670 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
672 if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
673 src = kmap_atomic(page);
674 copy_page(cmem, src);
677 memcpy(cmem, src, clen);
680 zcomp_strm_release(zram->comp, zstrm);
682 zs_unmap_object(meta->mem_pool, handle);
685 * Free memory associated with this sector
686 * before overwriting unused sectors.
688 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
689 zram_free_page(zram, index);
691 meta->table[index].handle = handle;
692 zram_set_obj_size(meta, index, clen);
693 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
696 atomic64_add(clen, &zram->stats.compr_data_size);
697 atomic64_inc(&zram->stats.pages_stored);
700 zcomp_strm_release(zram->comp, zstrm);
701 if (is_partial_io(bvec))
706 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
709 unsigned long start_time = jiffies;
712 generic_start_io_acct(rw, bvec->bv_len >> SECTOR_SHIFT,
716 atomic64_inc(&zram->stats.num_reads);
717 ret = zram_bvec_read(zram, bvec, index, offset);
719 atomic64_inc(&zram->stats.num_writes);
720 ret = zram_bvec_write(zram, bvec, index, offset);
723 generic_end_io_acct(rw, &zram->disk->part0, start_time);
727 atomic64_inc(&zram->stats.failed_reads);
729 atomic64_inc(&zram->stats.failed_writes);
736 * zram_bio_discard - handler on discard request
737 * @index: physical block index in PAGE_SIZE units
738 * @offset: byte offset within physical block
740 static void zram_bio_discard(struct zram *zram, u32 index,
741 int offset, struct bio *bio)
743 size_t n = bio->bi_iter.bi_size;
744 struct zram_meta *meta = zram->meta;
747 * zram manages data in physical block size units. Because logical block
748 * size isn't identical with physical block size on some arch, we
749 * could get a discard request pointing to a specific offset within a
750 * certain physical block. Although we can handle this request by
751 * reading that physiclal block and decompressing and partially zeroing
752 * and re-compressing and then re-storing it, this isn't reasonable
753 * because our intent with a discard request is to save memory. So
754 * skipping this logical block is appropriate here.
757 if (n <= (PAGE_SIZE - offset))
760 n -= (PAGE_SIZE - offset);
764 while (n >= PAGE_SIZE) {
765 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
766 zram_free_page(zram, index);
767 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
768 atomic64_inc(&zram->stats.notify_free);
774 static void zram_reset_device(struct zram *zram)
776 struct zram_meta *meta;
780 down_write(&zram->init_lock);
782 zram->limit_pages = 0;
784 if (!init_done(zram)) {
785 up_write(&zram->init_lock);
791 disksize = zram->disksize;
793 * Refcount will go down to 0 eventually and r/w handler
794 * cannot handle further I/O so it will bail out by
795 * check zram_meta_get.
799 * We want to free zram_meta in process context to avoid
800 * deadlock between reclaim path and any other locks.
802 wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);
805 memset(&zram->stats, 0, sizeof(zram->stats));
807 zram->max_comp_streams = 1;
809 set_capacity(zram->disk, 0);
810 part_stat_set_all(&zram->disk->part0, 0);
812 up_write(&zram->init_lock);
813 /* I/O operation under all of CPU are done so let's free */
814 zram_meta_free(meta, disksize);
818 static ssize_t disksize_store(struct device *dev,
819 struct device_attribute *attr, const char *buf, size_t len)
823 struct zram_meta *meta;
824 struct zram *zram = dev_to_zram(dev);
827 disksize = memparse(buf, NULL);
831 disksize = PAGE_ALIGN(disksize);
832 meta = zram_meta_alloc(zram->disk->first_minor, disksize);
836 comp = zcomp_create(zram->compressor, zram->max_comp_streams);
838 pr_info("Cannot initialise %s compressing backend\n",
844 down_write(&zram->init_lock);
845 if (init_done(zram)) {
846 pr_info("Cannot change disksize for initialized device\n");
848 goto out_destroy_comp;
851 init_waitqueue_head(&zram->io_done);
852 atomic_set(&zram->refcount, 1);
855 zram->disksize = disksize;
856 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
857 up_write(&zram->init_lock);
860 * Revalidate disk out of the init_lock to avoid lockdep splat.
861 * It's okay because disk's capacity is protected by init_lock
862 * so that revalidate_disk always sees up-to-date capacity.
864 revalidate_disk(zram->disk);
869 up_write(&zram->init_lock);
872 zram_meta_free(meta, disksize);
876 static ssize_t reset_store(struct device *dev,
877 struct device_attribute *attr, const char *buf, size_t len)
880 unsigned short do_reset;
882 struct block_device *bdev;
884 zram = dev_to_zram(dev);
885 bdev = bdget_disk(zram->disk, 0);
890 mutex_lock(&bdev->bd_mutex);
891 /* Do not reset an active device! */
892 if (bdev->bd_openers) {
897 ret = kstrtou16(buf, 10, &do_reset);
906 /* Make sure all pending I/O is finished */
908 zram_reset_device(zram);
910 mutex_unlock(&bdev->bd_mutex);
911 revalidate_disk(zram->disk);
917 mutex_unlock(&bdev->bd_mutex);
922 static void __zram_make_request(struct zram *zram, struct bio *bio)
927 struct bvec_iter iter;
929 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
930 offset = (bio->bi_iter.bi_sector &
931 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
933 if (unlikely(bio->bi_rw & REQ_DISCARD)) {
934 zram_bio_discard(zram, index, offset, bio);
939 rw = bio_data_dir(bio);
940 bio_for_each_segment(bvec, bio, iter) {
941 int max_transfer_size = PAGE_SIZE - offset;
943 if (bvec.bv_len > max_transfer_size) {
945 * zram_bvec_rw() can only make operation on a single
946 * zram page. Split the bio vector.
950 bv.bv_page = bvec.bv_page;
951 bv.bv_len = max_transfer_size;
952 bv.bv_offset = bvec.bv_offset;
954 if (zram_bvec_rw(zram, &bv, index, offset, rw) < 0)
957 bv.bv_len = bvec.bv_len - max_transfer_size;
958 bv.bv_offset += max_transfer_size;
959 if (zram_bvec_rw(zram, &bv, index + 1, 0, rw) < 0)
962 if (zram_bvec_rw(zram, &bvec, index, offset, rw) < 0)
965 update_position(&index, &offset, &bvec);
968 set_bit(BIO_UPTODATE, &bio->bi_flags);
977 * Handler function for all zram I/O requests.
979 static void zram_make_request(struct request_queue *queue, struct bio *bio)
981 struct zram *zram = queue->queuedata;
983 if (unlikely(!zram_meta_get(zram)))
986 if (!valid_io_request(zram, bio->bi_iter.bi_sector,
987 bio->bi_iter.bi_size)) {
988 atomic64_inc(&zram->stats.invalid_io);
992 __zram_make_request(zram, bio);
1001 static void zram_slot_free_notify(struct block_device *bdev,
1002 unsigned long index)
1005 struct zram_meta *meta;
1007 zram = bdev->bd_disk->private_data;
1010 bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
1011 zram_free_page(zram, index);
1012 bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
1013 atomic64_inc(&zram->stats.notify_free);
1016 static int zram_rw_page(struct block_device *bdev, sector_t sector,
1017 struct page *page, int rw)
1019 int offset, err = -EIO;
1024 zram = bdev->bd_disk->private_data;
1025 if (unlikely(!zram_meta_get(zram)))
1028 if (!valid_io_request(zram, sector, PAGE_SIZE)) {
1029 atomic64_inc(&zram->stats.invalid_io);
1034 index = sector >> SECTORS_PER_PAGE_SHIFT;
1035 offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT;
1038 bv.bv_len = PAGE_SIZE;
1041 err = zram_bvec_rw(zram, &bv, index, offset, rw);
1043 zram_meta_put(zram);
1046 * If I/O fails, just return error(ie, non-zero) without
1047 * calling page_endio.
1048 * It causes resubmit the I/O with bio request by upper functions
1049 * of rw_page(e.g., swap_readpage, __swap_writepage) and
1050 * bio->bi_end_io does things to handle the error
1051 * (e.g., SetPageError, set_page_dirty and extra works).
1054 page_endio(page, rw, 0);
1058 static const struct block_device_operations zram_devops = {
1059 .swap_slot_free_notify = zram_slot_free_notify,
1060 .rw_page = zram_rw_page,
1061 .owner = THIS_MODULE
1064 static DEVICE_ATTR_WO(compact);
1065 static DEVICE_ATTR_RW(disksize);
1066 static DEVICE_ATTR_RO(initstate);
1067 static DEVICE_ATTR_WO(reset);
1068 static DEVICE_ATTR_RO(orig_data_size);
1069 static DEVICE_ATTR_RO(mem_used_total);
1070 static DEVICE_ATTR_RW(mem_limit);
1071 static DEVICE_ATTR_RW(mem_used_max);
1072 static DEVICE_ATTR_RW(max_comp_streams);
1073 static DEVICE_ATTR_RW(comp_algorithm);
1075 static ssize_t io_stat_show(struct device *dev,
1076 struct device_attribute *attr, char *buf)
1078 struct zram *zram = dev_to_zram(dev);
1081 down_read(&zram->init_lock);
1082 ret = scnprintf(buf, PAGE_SIZE,
1083 "%8llu %8llu %8llu %8llu\n",
1084 (u64)atomic64_read(&zram->stats.failed_reads),
1085 (u64)atomic64_read(&zram->stats.failed_writes),
1086 (u64)atomic64_read(&zram->stats.invalid_io),
1087 (u64)atomic64_read(&zram->stats.notify_free));
1088 up_read(&zram->init_lock);
1093 static ssize_t mm_stat_show(struct device *dev,
1094 struct device_attribute *attr, char *buf)
1096 struct zram *zram = dev_to_zram(dev);
1097 u64 orig_size, mem_used = 0;
1101 down_read(&zram->init_lock);
1102 if (init_done(zram))
1103 mem_used = zs_get_total_pages(zram->meta->mem_pool);
1105 orig_size = atomic64_read(&zram->stats.pages_stored);
1106 max_used = atomic_long_read(&zram->stats.max_used_pages);
1108 ret = scnprintf(buf, PAGE_SIZE,
1109 "%8llu %8llu %8llu %8lu %8ld %8llu %8llu\n",
1110 orig_size << PAGE_SHIFT,
1111 (u64)atomic64_read(&zram->stats.compr_data_size),
1112 mem_used << PAGE_SHIFT,
1113 zram->limit_pages << PAGE_SHIFT,
1114 max_used << PAGE_SHIFT,
1115 (u64)atomic64_read(&zram->stats.zero_pages),
1116 (u64)atomic64_read(&zram->stats.num_migrated));
1117 up_read(&zram->init_lock);
1122 static DEVICE_ATTR_RO(io_stat);
1123 static DEVICE_ATTR_RO(mm_stat);
1124 ZRAM_ATTR_RO(num_reads);
1125 ZRAM_ATTR_RO(num_writes);
1126 ZRAM_ATTR_RO(failed_reads);
1127 ZRAM_ATTR_RO(failed_writes);
1128 ZRAM_ATTR_RO(invalid_io);
1129 ZRAM_ATTR_RO(notify_free);
1130 ZRAM_ATTR_RO(zero_pages);
1131 ZRAM_ATTR_RO(compr_data_size);
1133 static struct attribute *zram_disk_attrs[] = {
1134 &dev_attr_disksize.attr,
1135 &dev_attr_initstate.attr,
1136 &dev_attr_reset.attr,
1137 &dev_attr_num_reads.attr,
1138 &dev_attr_num_writes.attr,
1139 &dev_attr_failed_reads.attr,
1140 &dev_attr_failed_writes.attr,
1141 &dev_attr_compact.attr,
1142 &dev_attr_invalid_io.attr,
1143 &dev_attr_notify_free.attr,
1144 &dev_attr_zero_pages.attr,
1145 &dev_attr_orig_data_size.attr,
1146 &dev_attr_compr_data_size.attr,
1147 &dev_attr_mem_used_total.attr,
1148 &dev_attr_mem_limit.attr,
1149 &dev_attr_mem_used_max.attr,
1150 &dev_attr_max_comp_streams.attr,
1151 &dev_attr_comp_algorithm.attr,
1152 &dev_attr_io_stat.attr,
1153 &dev_attr_mm_stat.attr,
1157 static struct attribute_group zram_disk_attr_group = {
1158 .attrs = zram_disk_attrs,
1161 static int create_device(struct zram *zram, int device_id)
1163 struct request_queue *queue;
1166 init_rwsem(&zram->init_lock);
1168 queue = blk_alloc_queue(GFP_KERNEL);
1170 pr_err("Error allocating disk queue for device %d\n",
1175 blk_queue_make_request(queue, zram_make_request);
1177 /* gendisk structure */
1178 zram->disk = alloc_disk(1);
1180 pr_warn("Error allocating disk structure for device %d\n",
1183 goto out_free_queue;
1186 zram->disk->major = zram_major;
1187 zram->disk->first_minor = device_id;
1188 zram->disk->fops = &zram_devops;
1189 zram->disk->queue = queue;
1190 zram->disk->queue->queuedata = zram;
1191 zram->disk->private_data = zram;
1192 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1194 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1195 set_capacity(zram->disk, 0);
1196 /* zram devices sort of resembles non-rotational disks */
1197 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
1198 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1200 * To ensure that we always get PAGE_SIZE aligned
1201 * and n*PAGE_SIZED sized I/O requests.
1203 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1204 blk_queue_logical_block_size(zram->disk->queue,
1205 ZRAM_LOGICAL_BLOCK_SIZE);
1206 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1207 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1208 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1209 zram->disk->queue->limits.max_discard_sectors = UINT_MAX;
1211 * zram_bio_discard() will clear all logical blocks if logical block
1212 * size is identical with physical block size(PAGE_SIZE). But if it is
1213 * different, we will skip discarding some parts of logical blocks in
1214 * the part of the request range which isn't aligned to physical block
1215 * size. So we can't ensure that all discarded logical blocks are
1218 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1219 zram->disk->queue->limits.discard_zeroes_data = 1;
1221 zram->disk->queue->limits.discard_zeroes_data = 0;
1222 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
1224 add_disk(zram->disk);
1226 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
1227 &zram_disk_attr_group);
1229 pr_warn("Error creating sysfs group");
1232 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1234 zram->max_comp_streams = 1;
1238 del_gendisk(zram->disk);
1239 put_disk(zram->disk);
1241 blk_cleanup_queue(queue);
1246 static void destroy_devices(unsigned int nr)
1251 for (i = 0; i < nr; i++) {
1252 zram = &zram_devices[i];
1254 * Remove sysfs first, so no one will perform a disksize
1255 * store while we destroy the devices
1257 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
1258 &zram_disk_attr_group);
1260 zram_reset_device(zram);
1262 blk_cleanup_queue(zram->disk->queue);
1263 del_gendisk(zram->disk);
1264 put_disk(zram->disk);
1267 kfree(zram_devices);
1268 unregister_blkdev(zram_major, "zram");
1269 pr_info("Destroyed %u device(s)\n", nr);
1272 static int __init zram_init(void)
1276 if (num_devices > max_num_devices) {
1277 pr_warn("Invalid value for num_devices: %u\n",
1282 zram_major = register_blkdev(0, "zram");
1283 if (zram_major <= 0) {
1284 pr_warn("Unable to get major number\n");
1288 /* Allocate the device array and initialize each one */
1289 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
1290 if (!zram_devices) {
1291 unregister_blkdev(zram_major, "zram");
1295 for (dev_id = 0; dev_id < num_devices; dev_id++) {
1296 ret = create_device(&zram_devices[dev_id], dev_id);
1301 pr_info("Created %u device(s)\n", num_devices);
1305 destroy_devices(dev_id);
1309 static void __exit zram_exit(void)
1311 destroy_devices(num_devices);
1314 module_init(zram_init);
1315 module_exit(zram_exit);
1317 module_param(num_devices, uint, 0);
1318 MODULE_PARM_DESC(num_devices, "Number of zram devices");
1320 MODULE_LICENSE("Dual BSD/GPL");
1321 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1322 MODULE_DESCRIPTION("Compressed RAM Block Device");