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 #include <linux/module.h>
19 #include <linux/kernel.h>
20 #include <linux/bio.h>
21 #include <linux/bitops.h>
22 #include <linux/blkdev.h>
23 #include <linux/buffer_head.h>
24 #include <linux/device.h>
25 #include <linux/genhd.h>
26 #include <linux/highmem.h>
27 #include <linux/slab.h>
28 #include <linux/backing-dev.h>
29 #include <linux/string.h>
30 #include <linux/vmalloc.h>
31 #include <linux/err.h>
32 #include <linux/idr.h>
33 #include <linux/sysfs.h>
34 #include <linux/debugfs.h>
35 #include <linux/cpuhotplug.h>
36 #include <linux/part_stat.h>
40 static DEFINE_IDR(zram_index_idr);
41 /* idr index must be protected */
42 static DEFINE_MUTEX(zram_index_mutex);
44 static int zram_major;
45 static const char *default_compressor = CONFIG_ZRAM_DEF_COMP;
47 /* Module params (documentation at end) */
48 static unsigned int num_devices = 1;
50 * Pages that compress to sizes equals or greater than this are stored
51 * uncompressed in memory.
53 static size_t huge_class_size;
55 static const struct block_device_operations zram_devops;
56 static const struct block_device_operations zram_wb_devops;
58 static void zram_free_page(struct zram *zram, size_t index);
59 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
60 u32 index, int offset, struct bio *bio);
63 static int zram_slot_trylock(struct zram *zram, u32 index)
65 return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].flags);
68 static void zram_slot_lock(struct zram *zram, u32 index)
70 bit_spin_lock(ZRAM_LOCK, &zram->table[index].flags);
73 static void zram_slot_unlock(struct zram *zram, u32 index)
75 bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags);
78 static inline bool init_done(struct zram *zram)
80 return zram->disksize;
83 static inline struct zram *dev_to_zram(struct device *dev)
85 return (struct zram *)dev_to_disk(dev)->private_data;
88 static unsigned long zram_get_handle(struct zram *zram, u32 index)
90 return zram->table[index].handle;
93 static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle)
95 zram->table[index].handle = handle;
98 /* flag operations require table entry bit_spin_lock() being held */
99 static bool zram_test_flag(struct zram *zram, u32 index,
100 enum zram_pageflags flag)
102 return zram->table[index].flags & BIT(flag);
105 static void zram_set_flag(struct zram *zram, u32 index,
106 enum zram_pageflags flag)
108 zram->table[index].flags |= BIT(flag);
111 static void zram_clear_flag(struct zram *zram, u32 index,
112 enum zram_pageflags flag)
114 zram->table[index].flags &= ~BIT(flag);
117 static inline void zram_set_element(struct zram *zram, u32 index,
118 unsigned long element)
120 zram->table[index].element = element;
123 static unsigned long zram_get_element(struct zram *zram, u32 index)
125 return zram->table[index].element;
128 static size_t zram_get_obj_size(struct zram *zram, u32 index)
130 return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
133 static void zram_set_obj_size(struct zram *zram,
134 u32 index, size_t size)
136 unsigned long flags = zram->table[index].flags >> ZRAM_FLAG_SHIFT;
138 zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size;
141 static inline bool zram_allocated(struct zram *zram, u32 index)
143 return zram_get_obj_size(zram, index) ||
144 zram_test_flag(zram, index, ZRAM_SAME) ||
145 zram_test_flag(zram, index, ZRAM_WB);
148 #if PAGE_SIZE != 4096
149 static inline bool is_partial_io(struct bio_vec *bvec)
151 return bvec->bv_len != PAGE_SIZE;
154 static inline bool is_partial_io(struct bio_vec *bvec)
161 * Check if request is within bounds and aligned on zram logical blocks.
163 static inline bool valid_io_request(struct zram *zram,
164 sector_t start, unsigned int size)
168 /* unaligned request */
169 if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
171 if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
174 end = start + (size >> SECTOR_SHIFT);
175 bound = zram->disksize >> SECTOR_SHIFT;
176 /* out of range range */
177 if (unlikely(start >= bound || end > bound || start > end))
180 /* I/O request is valid */
184 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
186 *index += (*offset + bvec->bv_len) / PAGE_SIZE;
187 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
190 static inline void update_used_max(struct zram *zram,
191 const unsigned long pages)
193 unsigned long old_max, cur_max;
195 old_max = atomic_long_read(&zram->stats.max_used_pages);
200 old_max = atomic_long_cmpxchg(
201 &zram->stats.max_used_pages, cur_max, pages);
202 } while (old_max != cur_max);
205 static inline void zram_fill_page(void *ptr, unsigned long len,
208 WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long)));
209 memset_l(ptr, value, len / sizeof(unsigned long));
212 static bool page_same_filled(void *ptr, unsigned long *element)
216 unsigned int pos, last_pos = PAGE_SIZE / sizeof(*page) - 1;
218 page = (unsigned long *)ptr;
221 if (val != page[last_pos])
224 for (pos = 1; pos < last_pos; pos++) {
225 if (val != page[pos])
234 static ssize_t initstate_show(struct device *dev,
235 struct device_attribute *attr, char *buf)
238 struct zram *zram = dev_to_zram(dev);
240 down_read(&zram->init_lock);
241 val = init_done(zram);
242 up_read(&zram->init_lock);
244 return scnprintf(buf, PAGE_SIZE, "%u\n", val);
247 static ssize_t disksize_show(struct device *dev,
248 struct device_attribute *attr, char *buf)
250 struct zram *zram = dev_to_zram(dev);
252 return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize);
255 static ssize_t mem_limit_store(struct device *dev,
256 struct device_attribute *attr, const char *buf, size_t len)
260 struct zram *zram = dev_to_zram(dev);
262 limit = memparse(buf, &tmp);
263 if (buf == tmp) /* no chars parsed, invalid input */
266 down_write(&zram->init_lock);
267 zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
268 up_write(&zram->init_lock);
273 static ssize_t mem_used_max_store(struct device *dev,
274 struct device_attribute *attr, const char *buf, size_t len)
278 struct zram *zram = dev_to_zram(dev);
280 err = kstrtoul(buf, 10, &val);
284 down_read(&zram->init_lock);
285 if (init_done(zram)) {
286 atomic_long_set(&zram->stats.max_used_pages,
287 zs_get_total_pages(zram->mem_pool));
289 up_read(&zram->init_lock);
294 static ssize_t idle_store(struct device *dev,
295 struct device_attribute *attr, const char *buf, size_t len)
297 struct zram *zram = dev_to_zram(dev);
298 unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
301 if (!sysfs_streq(buf, "all"))
304 down_read(&zram->init_lock);
305 if (!init_done(zram)) {
306 up_read(&zram->init_lock);
310 for (index = 0; index < nr_pages; index++) {
312 * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race.
313 * See the comment in writeback_store.
315 zram_slot_lock(zram, index);
316 if (zram_allocated(zram, index) &&
317 !zram_test_flag(zram, index, ZRAM_UNDER_WB))
318 zram_set_flag(zram, index, ZRAM_IDLE);
319 zram_slot_unlock(zram, index);
322 up_read(&zram->init_lock);
327 #ifdef CONFIG_ZRAM_WRITEBACK
328 static ssize_t writeback_limit_enable_store(struct device *dev,
329 struct device_attribute *attr, const char *buf, size_t len)
331 struct zram *zram = dev_to_zram(dev);
333 ssize_t ret = -EINVAL;
335 if (kstrtoull(buf, 10, &val))
338 down_read(&zram->init_lock);
339 spin_lock(&zram->wb_limit_lock);
340 zram->wb_limit_enable = val;
341 spin_unlock(&zram->wb_limit_lock);
342 up_read(&zram->init_lock);
348 static ssize_t writeback_limit_enable_show(struct device *dev,
349 struct device_attribute *attr, char *buf)
352 struct zram *zram = dev_to_zram(dev);
354 down_read(&zram->init_lock);
355 spin_lock(&zram->wb_limit_lock);
356 val = zram->wb_limit_enable;
357 spin_unlock(&zram->wb_limit_lock);
358 up_read(&zram->init_lock);
360 return scnprintf(buf, PAGE_SIZE, "%d\n", val);
363 static ssize_t writeback_limit_store(struct device *dev,
364 struct device_attribute *attr, const char *buf, size_t len)
366 struct zram *zram = dev_to_zram(dev);
368 ssize_t ret = -EINVAL;
370 if (kstrtoull(buf, 10, &val))
373 down_read(&zram->init_lock);
374 spin_lock(&zram->wb_limit_lock);
375 zram->bd_wb_limit = val;
376 spin_unlock(&zram->wb_limit_lock);
377 up_read(&zram->init_lock);
383 static ssize_t writeback_limit_show(struct device *dev,
384 struct device_attribute *attr, char *buf)
387 struct zram *zram = dev_to_zram(dev);
389 down_read(&zram->init_lock);
390 spin_lock(&zram->wb_limit_lock);
391 val = zram->bd_wb_limit;
392 spin_unlock(&zram->wb_limit_lock);
393 up_read(&zram->init_lock);
395 return scnprintf(buf, PAGE_SIZE, "%llu\n", val);
398 static void reset_bdev(struct zram *zram)
400 struct block_device *bdev;
402 if (!zram->backing_dev)
406 blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
407 /* hope filp_close flush all of IO */
408 filp_close(zram->backing_dev, NULL);
409 zram->backing_dev = NULL;
411 zram->disk->fops = &zram_devops;
412 kvfree(zram->bitmap);
416 static ssize_t backing_dev_show(struct device *dev,
417 struct device_attribute *attr, char *buf)
420 struct zram *zram = dev_to_zram(dev);
424 down_read(&zram->init_lock);
425 file = zram->backing_dev;
427 memcpy(buf, "none\n", 5);
428 up_read(&zram->init_lock);
432 p = file_path(file, buf, PAGE_SIZE - 1);
439 memmove(buf, p, ret);
442 up_read(&zram->init_lock);
446 static ssize_t backing_dev_store(struct device *dev,
447 struct device_attribute *attr, const char *buf, size_t len)
451 struct file *backing_dev = NULL;
453 struct address_space *mapping;
454 unsigned int bitmap_sz;
455 unsigned long nr_pages, *bitmap = NULL;
456 struct block_device *bdev = NULL;
458 struct zram *zram = dev_to_zram(dev);
460 file_name = kmalloc(PATH_MAX, GFP_KERNEL);
464 down_write(&zram->init_lock);
465 if (init_done(zram)) {
466 pr_info("Can't setup backing device for initialized device\n");
471 strlcpy(file_name, buf, PATH_MAX);
472 /* ignore trailing newline */
473 sz = strlen(file_name);
474 if (sz > 0 && file_name[sz - 1] == '\n')
475 file_name[sz - 1] = 0x00;
477 backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);
478 if (IS_ERR(backing_dev)) {
479 err = PTR_ERR(backing_dev);
484 mapping = backing_dev->f_mapping;
485 inode = mapping->host;
487 /* Support only block device in this moment */
488 if (!S_ISBLK(inode->i_mode)) {
493 bdev = blkdev_get_by_dev(inode->i_rdev,
494 FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram);
501 nr_pages = i_size_read(inode) >> PAGE_SHIFT;
502 bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long);
503 bitmap = kvzalloc(bitmap_sz, GFP_KERNEL);
512 zram->backing_dev = backing_dev;
513 zram->bitmap = bitmap;
514 zram->nr_pages = nr_pages;
516 * With writeback feature, zram does asynchronous IO so it's no longer
517 * synchronous device so let's remove synchronous io flag. Othewise,
518 * upper layer(e.g., swap) could wait IO completion rather than
519 * (submit and return), which will cause system sluggish.
520 * Furthermore, when the IO function returns(e.g., swap_readpage),
521 * upper layer expects IO was done so it could deallocate the page
522 * freely but in fact, IO is going on so finally could cause
523 * use-after-free when the IO is really done.
525 zram->disk->fops = &zram_wb_devops;
526 up_write(&zram->init_lock);
528 pr_info("setup backing device %s\n", file_name);
536 blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
539 filp_close(backing_dev, NULL);
541 up_write(&zram->init_lock);
548 static unsigned long alloc_block_bdev(struct zram *zram)
550 unsigned long blk_idx = 1;
552 /* skip 0 bit to confuse zram.handle = 0 */
553 blk_idx = find_next_zero_bit(zram->bitmap, zram->nr_pages, blk_idx);
554 if (blk_idx == zram->nr_pages)
557 if (test_and_set_bit(blk_idx, zram->bitmap))
560 atomic64_inc(&zram->stats.bd_count);
564 static void free_block_bdev(struct zram *zram, unsigned long blk_idx)
568 was_set = test_and_clear_bit(blk_idx, zram->bitmap);
569 WARN_ON_ONCE(!was_set);
570 atomic64_dec(&zram->stats.bd_count);
573 static void zram_page_end_io(struct bio *bio)
575 struct page *page = bio_first_page_all(bio);
577 page_endio(page, op_is_write(bio_op(bio)),
578 blk_status_to_errno(bio->bi_status));
583 * Returns 1 if the submission is successful.
585 static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
586 unsigned long entry, struct bio *parent)
590 bio = bio_alloc(GFP_ATOMIC, 1);
594 bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9);
595 bio_set_dev(bio, zram->bdev);
596 if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, bvec->bv_offset)) {
602 bio->bi_opf = REQ_OP_READ;
603 bio->bi_end_io = zram_page_end_io;
605 bio->bi_opf = parent->bi_opf;
606 bio_chain(bio, parent);
613 #define PAGE_WB_SIG "page_index="
615 #define PAGE_WRITEBACK 0
616 #define HUGE_WRITEBACK 1
617 #define IDLE_WRITEBACK 2
620 static ssize_t writeback_store(struct device *dev,
621 struct device_attribute *attr, const char *buf, size_t len)
623 struct zram *zram = dev_to_zram(dev);
624 unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
625 unsigned long index = 0;
627 struct bio_vec bio_vec;
631 unsigned long blk_idx = 0;
633 if (sysfs_streq(buf, "idle"))
634 mode = IDLE_WRITEBACK;
635 else if (sysfs_streq(buf, "huge"))
636 mode = HUGE_WRITEBACK;
638 if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1))
641 if (kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index) ||
646 mode = PAGE_WRITEBACK;
649 down_read(&zram->init_lock);
650 if (!init_done(zram)) {
652 goto release_init_lock;
655 if (!zram->backing_dev) {
657 goto release_init_lock;
660 page = alloc_page(GFP_KERNEL);
663 goto release_init_lock;
666 for (; nr_pages != 0; index++, nr_pages--) {
670 bvec.bv_len = PAGE_SIZE;
673 spin_lock(&zram->wb_limit_lock);
674 if (zram->wb_limit_enable && !zram->bd_wb_limit) {
675 spin_unlock(&zram->wb_limit_lock);
679 spin_unlock(&zram->wb_limit_lock);
682 blk_idx = alloc_block_bdev(zram);
689 zram_slot_lock(zram, index);
690 if (!zram_allocated(zram, index))
693 if (zram_test_flag(zram, index, ZRAM_WB) ||
694 zram_test_flag(zram, index, ZRAM_SAME) ||
695 zram_test_flag(zram, index, ZRAM_UNDER_WB))
698 if (mode == IDLE_WRITEBACK &&
699 !zram_test_flag(zram, index, ZRAM_IDLE))
701 if (mode == HUGE_WRITEBACK &&
702 !zram_test_flag(zram, index, ZRAM_HUGE))
705 * Clearing ZRAM_UNDER_WB is duty of caller.
706 * IOW, zram_free_page never clear it.
708 zram_set_flag(zram, index, ZRAM_UNDER_WB);
709 /* Need for hugepage writeback racing */
710 zram_set_flag(zram, index, ZRAM_IDLE);
711 zram_slot_unlock(zram, index);
712 if (zram_bvec_read(zram, &bvec, index, 0, NULL)) {
713 zram_slot_lock(zram, index);
714 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
715 zram_clear_flag(zram, index, ZRAM_IDLE);
716 zram_slot_unlock(zram, index);
720 bio_init(&bio, &bio_vec, 1);
721 bio_set_dev(&bio, zram->bdev);
722 bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9);
723 bio.bi_opf = REQ_OP_WRITE | REQ_SYNC;
725 bio_add_page(&bio, bvec.bv_page, bvec.bv_len,
728 * XXX: A single page IO would be inefficient for write
729 * but it would be not bad as starter.
731 err = submit_bio_wait(&bio);
733 zram_slot_lock(zram, index);
734 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
735 zram_clear_flag(zram, index, ZRAM_IDLE);
736 zram_slot_unlock(zram, index);
738 * Return last IO error unless every IO were
745 atomic64_inc(&zram->stats.bd_writes);
747 * We released zram_slot_lock so need to check if the slot was
748 * changed. If there is freeing for the slot, we can catch it
749 * easily by zram_allocated.
750 * A subtle case is the slot is freed/reallocated/marked as
751 * ZRAM_IDLE again. To close the race, idle_store doesn't
752 * mark ZRAM_IDLE once it found the slot was ZRAM_UNDER_WB.
753 * Thus, we could close the race by checking ZRAM_IDLE bit.
755 zram_slot_lock(zram, index);
756 if (!zram_allocated(zram, index) ||
757 !zram_test_flag(zram, index, ZRAM_IDLE)) {
758 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
759 zram_clear_flag(zram, index, ZRAM_IDLE);
763 zram_free_page(zram, index);
764 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
765 zram_set_flag(zram, index, ZRAM_WB);
766 zram_set_element(zram, index, blk_idx);
768 atomic64_inc(&zram->stats.pages_stored);
769 spin_lock(&zram->wb_limit_lock);
770 if (zram->wb_limit_enable && zram->bd_wb_limit > 0)
771 zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12);
772 spin_unlock(&zram->wb_limit_lock);
774 zram_slot_unlock(zram, index);
778 free_block_bdev(zram, blk_idx);
781 up_read(&zram->init_lock);
787 struct work_struct work;
794 #if PAGE_SIZE != 4096
795 static void zram_sync_read(struct work_struct *work)
797 struct zram_work *zw = container_of(work, struct zram_work, work);
798 struct zram *zram = zw->zram;
799 unsigned long entry = zw->entry;
800 struct bio *bio = zw->bio;
802 read_from_bdev_async(zram, &zw->bvec, entry, bio);
806 * Block layer want one ->submit_bio to be active at a time, so if we use
807 * chained IO with parent IO in same context, it's a deadlock. To avoid that,
808 * use a worker thread context.
810 static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec,
811 unsigned long entry, struct bio *bio)
813 struct zram_work work;
820 INIT_WORK_ONSTACK(&work.work, zram_sync_read);
821 queue_work(system_unbound_wq, &work.work);
822 flush_work(&work.work);
823 destroy_work_on_stack(&work.work);
828 static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec,
829 unsigned long entry, struct bio *bio)
836 static int read_from_bdev(struct zram *zram, struct bio_vec *bvec,
837 unsigned long entry, struct bio *parent, bool sync)
839 atomic64_inc(&zram->stats.bd_reads);
841 return read_from_bdev_sync(zram, bvec, entry, parent);
843 return read_from_bdev_async(zram, bvec, entry, parent);
846 static inline void reset_bdev(struct zram *zram) {};
847 static int read_from_bdev(struct zram *zram, struct bio_vec *bvec,
848 unsigned long entry, struct bio *parent, bool sync)
853 static void free_block_bdev(struct zram *zram, unsigned long blk_idx) {};
856 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
858 static struct dentry *zram_debugfs_root;
860 static void zram_debugfs_create(void)
862 zram_debugfs_root = debugfs_create_dir("zram", NULL);
865 static void zram_debugfs_destroy(void)
867 debugfs_remove_recursive(zram_debugfs_root);
870 static void zram_accessed(struct zram *zram, u32 index)
872 zram_clear_flag(zram, index, ZRAM_IDLE);
873 zram->table[index].ac_time = ktime_get_boottime();
876 static ssize_t read_block_state(struct file *file, char __user *buf,
877 size_t count, loff_t *ppos)
880 ssize_t index, written = 0;
881 struct zram *zram = file->private_data;
882 unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
883 struct timespec64 ts;
885 kbuf = kvmalloc(count, GFP_KERNEL);
889 down_read(&zram->init_lock);
890 if (!init_done(zram)) {
891 up_read(&zram->init_lock);
896 for (index = *ppos; index < nr_pages; index++) {
899 zram_slot_lock(zram, index);
900 if (!zram_allocated(zram, index))
903 ts = ktime_to_timespec64(zram->table[index].ac_time);
904 copied = snprintf(kbuf + written, count,
905 "%12zd %12lld.%06lu %c%c%c%c\n",
906 index, (s64)ts.tv_sec,
907 ts.tv_nsec / NSEC_PER_USEC,
908 zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.',
909 zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.',
910 zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.',
911 zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.');
913 if (count < copied) {
914 zram_slot_unlock(zram, index);
920 zram_slot_unlock(zram, index);
924 up_read(&zram->init_lock);
925 if (copy_to_user(buf, kbuf, written))
932 static const struct file_operations proc_zram_block_state_op = {
934 .read = read_block_state,
935 .llseek = default_llseek,
938 static void zram_debugfs_register(struct zram *zram)
940 if (!zram_debugfs_root)
943 zram->debugfs_dir = debugfs_create_dir(zram->disk->disk_name,
945 debugfs_create_file("block_state", 0400, zram->debugfs_dir,
946 zram, &proc_zram_block_state_op);
949 static void zram_debugfs_unregister(struct zram *zram)
951 debugfs_remove_recursive(zram->debugfs_dir);
954 static void zram_debugfs_create(void) {};
955 static void zram_debugfs_destroy(void) {};
956 static void zram_accessed(struct zram *zram, u32 index)
958 zram_clear_flag(zram, index, ZRAM_IDLE);
960 static void zram_debugfs_register(struct zram *zram) {};
961 static void zram_debugfs_unregister(struct zram *zram) {};
965 * We switched to per-cpu streams and this attr is not needed anymore.
966 * However, we will keep it around for some time, because:
967 * a) we may revert per-cpu streams in the future
968 * b) it's visible to user space and we need to follow our 2 years
969 * retirement rule; but we already have a number of 'soon to be
970 * altered' attrs, so max_comp_streams need to wait for the next
973 static ssize_t max_comp_streams_show(struct device *dev,
974 struct device_attribute *attr, char *buf)
976 return scnprintf(buf, PAGE_SIZE, "%d\n", num_online_cpus());
979 static ssize_t max_comp_streams_store(struct device *dev,
980 struct device_attribute *attr, const char *buf, size_t len)
985 static ssize_t comp_algorithm_show(struct device *dev,
986 struct device_attribute *attr, char *buf)
989 struct zram *zram = dev_to_zram(dev);
991 down_read(&zram->init_lock);
992 sz = zcomp_available_show(zram->compressor, buf);
993 up_read(&zram->init_lock);
998 static ssize_t comp_algorithm_store(struct device *dev,
999 struct device_attribute *attr, const char *buf, size_t len)
1001 struct zram *zram = dev_to_zram(dev);
1002 char compressor[ARRAY_SIZE(zram->compressor)];
1005 strlcpy(compressor, buf, sizeof(compressor));
1006 /* ignore trailing newline */
1007 sz = strlen(compressor);
1008 if (sz > 0 && compressor[sz - 1] == '\n')
1009 compressor[sz - 1] = 0x00;
1011 if (!zcomp_available_algorithm(compressor))
1014 down_write(&zram->init_lock);
1015 if (init_done(zram)) {
1016 up_write(&zram->init_lock);
1017 pr_info("Can't change algorithm for initialized device\n");
1021 strcpy(zram->compressor, compressor);
1022 up_write(&zram->init_lock);
1026 static ssize_t compact_store(struct device *dev,
1027 struct device_attribute *attr, const char *buf, size_t len)
1029 struct zram *zram = dev_to_zram(dev);
1031 down_read(&zram->init_lock);
1032 if (!init_done(zram)) {
1033 up_read(&zram->init_lock);
1037 zs_compact(zram->mem_pool);
1038 up_read(&zram->init_lock);
1043 static ssize_t io_stat_show(struct device *dev,
1044 struct device_attribute *attr, char *buf)
1046 struct zram *zram = dev_to_zram(dev);
1049 down_read(&zram->init_lock);
1050 ret = scnprintf(buf, PAGE_SIZE,
1051 "%8llu %8llu %8llu %8llu\n",
1052 (u64)atomic64_read(&zram->stats.failed_reads),
1053 (u64)atomic64_read(&zram->stats.failed_writes),
1054 (u64)atomic64_read(&zram->stats.invalid_io),
1055 (u64)atomic64_read(&zram->stats.notify_free));
1056 up_read(&zram->init_lock);
1061 static ssize_t mm_stat_show(struct device *dev,
1062 struct device_attribute *attr, char *buf)
1064 struct zram *zram = dev_to_zram(dev);
1065 struct zs_pool_stats pool_stats;
1066 u64 orig_size, mem_used = 0;
1070 memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats));
1072 down_read(&zram->init_lock);
1073 if (init_done(zram)) {
1074 mem_used = zs_get_total_pages(zram->mem_pool);
1075 zs_pool_stats(zram->mem_pool, &pool_stats);
1078 orig_size = atomic64_read(&zram->stats.pages_stored);
1079 max_used = atomic_long_read(&zram->stats.max_used_pages);
1081 ret = scnprintf(buf, PAGE_SIZE,
1082 "%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu %8llu\n",
1083 orig_size << PAGE_SHIFT,
1084 (u64)atomic64_read(&zram->stats.compr_data_size),
1085 mem_used << PAGE_SHIFT,
1086 zram->limit_pages << PAGE_SHIFT,
1087 max_used << PAGE_SHIFT,
1088 (u64)atomic64_read(&zram->stats.same_pages),
1089 atomic_long_read(&pool_stats.pages_compacted),
1090 (u64)atomic64_read(&zram->stats.huge_pages),
1091 (u64)atomic64_read(&zram->stats.huge_pages_since));
1092 up_read(&zram->init_lock);
1097 #ifdef CONFIG_ZRAM_WRITEBACK
1098 #define FOUR_K(x) ((x) * (1 << (PAGE_SHIFT - 12)))
1099 static ssize_t bd_stat_show(struct device *dev,
1100 struct device_attribute *attr, char *buf)
1102 struct zram *zram = dev_to_zram(dev);
1105 down_read(&zram->init_lock);
1106 ret = scnprintf(buf, PAGE_SIZE,
1107 "%8llu %8llu %8llu\n",
1108 FOUR_K((u64)atomic64_read(&zram->stats.bd_count)),
1109 FOUR_K((u64)atomic64_read(&zram->stats.bd_reads)),
1110 FOUR_K((u64)atomic64_read(&zram->stats.bd_writes)));
1111 up_read(&zram->init_lock);
1117 static ssize_t debug_stat_show(struct device *dev,
1118 struct device_attribute *attr, char *buf)
1121 struct zram *zram = dev_to_zram(dev);
1124 down_read(&zram->init_lock);
1125 ret = scnprintf(buf, PAGE_SIZE,
1126 "version: %d\n%8llu %8llu\n",
1128 (u64)atomic64_read(&zram->stats.writestall),
1129 (u64)atomic64_read(&zram->stats.miss_free));
1130 up_read(&zram->init_lock);
1135 static DEVICE_ATTR_RO(io_stat);
1136 static DEVICE_ATTR_RO(mm_stat);
1137 #ifdef CONFIG_ZRAM_WRITEBACK
1138 static DEVICE_ATTR_RO(bd_stat);
1140 static DEVICE_ATTR_RO(debug_stat);
1142 static void zram_meta_free(struct zram *zram, u64 disksize)
1144 size_t num_pages = disksize >> PAGE_SHIFT;
1147 /* Free all pages that are still in this zram device */
1148 for (index = 0; index < num_pages; index++)
1149 zram_free_page(zram, index);
1151 zs_destroy_pool(zram->mem_pool);
1155 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
1159 num_pages = disksize >> PAGE_SHIFT;
1160 zram->table = vzalloc(array_size(num_pages, sizeof(*zram->table)));
1164 zram->mem_pool = zs_create_pool(zram->disk->disk_name);
1165 if (!zram->mem_pool) {
1170 if (!huge_class_size)
1171 huge_class_size = zs_huge_class_size(zram->mem_pool);
1176 * To protect concurrent access to the same index entry,
1177 * caller should hold this table index entry's bit_spinlock to
1178 * indicate this index entry is accessing.
1180 static void zram_free_page(struct zram *zram, size_t index)
1182 unsigned long handle;
1184 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
1185 zram->table[index].ac_time = 0;
1187 if (zram_test_flag(zram, index, ZRAM_IDLE))
1188 zram_clear_flag(zram, index, ZRAM_IDLE);
1190 if (zram_test_flag(zram, index, ZRAM_HUGE)) {
1191 zram_clear_flag(zram, index, ZRAM_HUGE);
1192 atomic64_dec(&zram->stats.huge_pages);
1195 if (zram_test_flag(zram, index, ZRAM_WB)) {
1196 zram_clear_flag(zram, index, ZRAM_WB);
1197 free_block_bdev(zram, zram_get_element(zram, index));
1202 * No memory is allocated for same element filled pages.
1203 * Simply clear same page flag.
1205 if (zram_test_flag(zram, index, ZRAM_SAME)) {
1206 zram_clear_flag(zram, index, ZRAM_SAME);
1207 atomic64_dec(&zram->stats.same_pages);
1211 handle = zram_get_handle(zram, index);
1215 zs_free(zram->mem_pool, handle);
1217 atomic64_sub(zram_get_obj_size(zram, index),
1218 &zram->stats.compr_data_size);
1220 atomic64_dec(&zram->stats.pages_stored);
1221 zram_set_handle(zram, index, 0);
1222 zram_set_obj_size(zram, index, 0);
1223 WARN_ON_ONCE(zram->table[index].flags &
1224 ~(1UL << ZRAM_LOCK | 1UL << ZRAM_UNDER_WB));
1227 static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
1228 struct bio *bio, bool partial_io)
1230 struct zcomp_strm *zstrm;
1231 unsigned long handle;
1236 zram_slot_lock(zram, index);
1237 if (zram_test_flag(zram, index, ZRAM_WB)) {
1238 struct bio_vec bvec;
1240 zram_slot_unlock(zram, index);
1242 bvec.bv_page = page;
1243 bvec.bv_len = PAGE_SIZE;
1245 return read_from_bdev(zram, &bvec,
1246 zram_get_element(zram, index),
1250 handle = zram_get_handle(zram, index);
1251 if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) {
1252 unsigned long value;
1255 value = handle ? zram_get_element(zram, index) : 0;
1256 mem = kmap_atomic(page);
1257 zram_fill_page(mem, PAGE_SIZE, value);
1259 zram_slot_unlock(zram, index);
1263 size = zram_get_obj_size(zram, index);
1265 if (size != PAGE_SIZE)
1266 zstrm = zcomp_stream_get(zram->comp);
1268 src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
1269 if (size == PAGE_SIZE) {
1270 dst = kmap_atomic(page);
1271 memcpy(dst, src, PAGE_SIZE);
1275 dst = kmap_atomic(page);
1276 ret = zcomp_decompress(zstrm, src, size, dst);
1278 zcomp_stream_put(zram->comp);
1280 zs_unmap_object(zram->mem_pool, handle);
1281 zram_slot_unlock(zram, index);
1283 /* Should NEVER happen. Return bio error if it does. */
1285 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
1290 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
1291 u32 index, int offset, struct bio *bio)
1296 page = bvec->bv_page;
1297 if (is_partial_io(bvec)) {
1298 /* Use a temporary buffer to decompress the page */
1299 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
1304 ret = __zram_bvec_read(zram, page, index, bio, is_partial_io(bvec));
1308 if (is_partial_io(bvec)) {
1309 void *dst = kmap_atomic(bvec->bv_page);
1310 void *src = kmap_atomic(page);
1312 memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len);
1317 if (is_partial_io(bvec))
1323 static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
1324 u32 index, struct bio *bio)
1327 unsigned long alloced_pages;
1328 unsigned long handle = 0;
1329 unsigned int comp_len = 0;
1330 void *src, *dst, *mem;
1331 struct zcomp_strm *zstrm;
1332 struct page *page = bvec->bv_page;
1333 unsigned long element = 0;
1334 enum zram_pageflags flags = 0;
1336 mem = kmap_atomic(page);
1337 if (page_same_filled(mem, &element)) {
1339 /* Free memory associated with this sector now. */
1341 atomic64_inc(&zram->stats.same_pages);
1347 zstrm = zcomp_stream_get(zram->comp);
1348 src = kmap_atomic(page);
1349 ret = zcomp_compress(zstrm, src, &comp_len);
1352 if (unlikely(ret)) {
1353 zcomp_stream_put(zram->comp);
1354 pr_err("Compression failed! err=%d\n", ret);
1355 zs_free(zram->mem_pool, handle);
1359 if (comp_len >= huge_class_size)
1360 comp_len = PAGE_SIZE;
1362 * handle allocation has 2 paths:
1363 * a) fast path is executed with preemption disabled (for
1364 * per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear,
1365 * since we can't sleep;
1366 * b) slow path enables preemption and attempts to allocate
1367 * the page with __GFP_DIRECT_RECLAIM bit set. we have to
1368 * put per-cpu compression stream and, thus, to re-do
1369 * the compression once handle is allocated.
1371 * if we have a 'non-null' handle here then we are coming
1372 * from the slow path and handle has already been allocated.
1375 handle = zs_malloc(zram->mem_pool, comp_len,
1376 __GFP_KSWAPD_RECLAIM |
1381 zcomp_stream_put(zram->comp);
1382 atomic64_inc(&zram->stats.writestall);
1383 handle = zs_malloc(zram->mem_pool, comp_len,
1384 GFP_NOIO | __GFP_HIGHMEM |
1387 goto compress_again;
1391 alloced_pages = zs_get_total_pages(zram->mem_pool);
1392 update_used_max(zram, alloced_pages);
1394 if (zram->limit_pages && alloced_pages > zram->limit_pages) {
1395 zcomp_stream_put(zram->comp);
1396 zs_free(zram->mem_pool, handle);
1400 dst = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
1402 src = zstrm->buffer;
1403 if (comp_len == PAGE_SIZE)
1404 src = kmap_atomic(page);
1405 memcpy(dst, src, comp_len);
1406 if (comp_len == PAGE_SIZE)
1409 zcomp_stream_put(zram->comp);
1410 zs_unmap_object(zram->mem_pool, handle);
1411 atomic64_add(comp_len, &zram->stats.compr_data_size);
1414 * Free memory associated with this sector
1415 * before overwriting unused sectors.
1417 zram_slot_lock(zram, index);
1418 zram_free_page(zram, index);
1420 if (comp_len == PAGE_SIZE) {
1421 zram_set_flag(zram, index, ZRAM_HUGE);
1422 atomic64_inc(&zram->stats.huge_pages);
1423 atomic64_inc(&zram->stats.huge_pages_since);
1427 zram_set_flag(zram, index, flags);
1428 zram_set_element(zram, index, element);
1430 zram_set_handle(zram, index, handle);
1431 zram_set_obj_size(zram, index, comp_len);
1433 zram_slot_unlock(zram, index);
1436 atomic64_inc(&zram->stats.pages_stored);
1440 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
1441 u32 index, int offset, struct bio *bio)
1444 struct page *page = NULL;
1449 if (is_partial_io(bvec)) {
1452 * This is a partial IO. We need to read the full page
1453 * before to write the changes.
1455 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
1459 ret = __zram_bvec_read(zram, page, index, bio, true);
1463 src = kmap_atomic(bvec->bv_page);
1464 dst = kmap_atomic(page);
1465 memcpy(dst + offset, src + bvec->bv_offset, bvec->bv_len);
1470 vec.bv_len = PAGE_SIZE;
1474 ret = __zram_bvec_write(zram, &vec, index, bio);
1476 if (is_partial_io(bvec))
1482 * zram_bio_discard - handler on discard request
1483 * @index: physical block index in PAGE_SIZE units
1484 * @offset: byte offset within physical block
1486 static void zram_bio_discard(struct zram *zram, u32 index,
1487 int offset, struct bio *bio)
1489 size_t n = bio->bi_iter.bi_size;
1492 * zram manages data in physical block size units. Because logical block
1493 * size isn't identical with physical block size on some arch, we
1494 * could get a discard request pointing to a specific offset within a
1495 * certain physical block. Although we can handle this request by
1496 * reading that physiclal block and decompressing and partially zeroing
1497 * and re-compressing and then re-storing it, this isn't reasonable
1498 * because our intent with a discard request is to save memory. So
1499 * skipping this logical block is appropriate here.
1502 if (n <= (PAGE_SIZE - offset))
1505 n -= (PAGE_SIZE - offset);
1509 while (n >= PAGE_SIZE) {
1510 zram_slot_lock(zram, index);
1511 zram_free_page(zram, index);
1512 zram_slot_unlock(zram, index);
1513 atomic64_inc(&zram->stats.notify_free);
1520 * Returns errno if it has some problem. Otherwise return 0 or 1.
1521 * Returns 0 if IO request was done synchronously
1522 * Returns 1 if IO request was successfully submitted.
1524 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
1525 int offset, unsigned int op, struct bio *bio)
1529 if (!op_is_write(op)) {
1530 atomic64_inc(&zram->stats.num_reads);
1531 ret = zram_bvec_read(zram, bvec, index, offset, bio);
1532 flush_dcache_page(bvec->bv_page);
1534 atomic64_inc(&zram->stats.num_writes);
1535 ret = zram_bvec_write(zram, bvec, index, offset, bio);
1538 zram_slot_lock(zram, index);
1539 zram_accessed(zram, index);
1540 zram_slot_unlock(zram, index);
1542 if (unlikely(ret < 0)) {
1543 if (!op_is_write(op))
1544 atomic64_inc(&zram->stats.failed_reads);
1546 atomic64_inc(&zram->stats.failed_writes);
1552 static void __zram_make_request(struct zram *zram, struct bio *bio)
1556 struct bio_vec bvec;
1557 struct bvec_iter iter;
1558 unsigned long start_time;
1560 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
1561 offset = (bio->bi_iter.bi_sector &
1562 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
1564 switch (bio_op(bio)) {
1565 case REQ_OP_DISCARD:
1566 case REQ_OP_WRITE_ZEROES:
1567 zram_bio_discard(zram, index, offset, bio);
1574 start_time = bio_start_io_acct(bio);
1575 bio_for_each_segment(bvec, bio, iter) {
1576 struct bio_vec bv = bvec;
1577 unsigned int unwritten = bvec.bv_len;
1580 bv.bv_len = min_t(unsigned int, PAGE_SIZE - offset,
1582 if (zram_bvec_rw(zram, &bv, index, offset,
1583 bio_op(bio), bio) < 0) {
1584 bio->bi_status = BLK_STS_IOERR;
1588 bv.bv_offset += bv.bv_len;
1589 unwritten -= bv.bv_len;
1591 update_position(&index, &offset, &bv);
1592 } while (unwritten);
1594 bio_end_io_acct(bio, start_time);
1599 * Handler function for all zram I/O requests.
1601 static blk_qc_t zram_submit_bio(struct bio *bio)
1603 struct zram *zram = bio->bi_bdev->bd_disk->private_data;
1605 if (!valid_io_request(zram, bio->bi_iter.bi_sector,
1606 bio->bi_iter.bi_size)) {
1607 atomic64_inc(&zram->stats.invalid_io);
1611 __zram_make_request(zram, bio);
1612 return BLK_QC_T_NONE;
1616 return BLK_QC_T_NONE;
1619 static void zram_slot_free_notify(struct block_device *bdev,
1620 unsigned long index)
1624 zram = bdev->bd_disk->private_data;
1626 atomic64_inc(&zram->stats.notify_free);
1627 if (!zram_slot_trylock(zram, index)) {
1628 atomic64_inc(&zram->stats.miss_free);
1632 zram_free_page(zram, index);
1633 zram_slot_unlock(zram, index);
1636 static int zram_rw_page(struct block_device *bdev, sector_t sector,
1637 struct page *page, unsigned int op)
1643 unsigned long start_time;
1645 if (PageTransHuge(page))
1647 zram = bdev->bd_disk->private_data;
1649 if (!valid_io_request(zram, sector, PAGE_SIZE)) {
1650 atomic64_inc(&zram->stats.invalid_io);
1655 index = sector >> SECTORS_PER_PAGE_SHIFT;
1656 offset = (sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
1659 bv.bv_len = PAGE_SIZE;
1662 start_time = disk_start_io_acct(bdev->bd_disk, SECTORS_PER_PAGE, op);
1663 ret = zram_bvec_rw(zram, &bv, index, offset, op, NULL);
1664 disk_end_io_acct(bdev->bd_disk, op, start_time);
1667 * If I/O fails, just return error(ie, non-zero) without
1668 * calling page_endio.
1669 * It causes resubmit the I/O with bio request by upper functions
1670 * of rw_page(e.g., swap_readpage, __swap_writepage) and
1671 * bio->bi_end_io does things to handle the error
1672 * (e.g., SetPageError, set_page_dirty and extra works).
1674 if (unlikely(ret < 0))
1679 page_endio(page, op_is_write(op), 0);
1690 static void zram_reset_device(struct zram *zram)
1695 down_write(&zram->init_lock);
1697 zram->limit_pages = 0;
1699 if (!init_done(zram)) {
1700 up_write(&zram->init_lock);
1705 disksize = zram->disksize;
1708 set_capacity_and_notify(zram->disk, 0);
1709 part_stat_set_all(zram->disk->part0, 0);
1711 up_write(&zram->init_lock);
1712 /* I/O operation under all of CPU are done so let's free */
1713 zram_meta_free(zram, disksize);
1714 memset(&zram->stats, 0, sizeof(zram->stats));
1715 zcomp_destroy(comp);
1719 static ssize_t disksize_store(struct device *dev,
1720 struct device_attribute *attr, const char *buf, size_t len)
1724 struct zram *zram = dev_to_zram(dev);
1727 disksize = memparse(buf, NULL);
1731 down_write(&zram->init_lock);
1732 if (init_done(zram)) {
1733 pr_info("Cannot change disksize for initialized device\n");
1738 disksize = PAGE_ALIGN(disksize);
1739 if (!zram_meta_alloc(zram, disksize)) {
1744 comp = zcomp_create(zram->compressor);
1746 pr_err("Cannot initialise %s compressing backend\n",
1748 err = PTR_ERR(comp);
1753 zram->disksize = disksize;
1754 set_capacity_and_notify(zram->disk, zram->disksize >> SECTOR_SHIFT);
1755 up_write(&zram->init_lock);
1760 zram_meta_free(zram, disksize);
1762 up_write(&zram->init_lock);
1766 static ssize_t reset_store(struct device *dev,
1767 struct device_attribute *attr, const char *buf, size_t len)
1770 unsigned short do_reset;
1772 struct block_device *bdev;
1774 ret = kstrtou16(buf, 10, &do_reset);
1781 zram = dev_to_zram(dev);
1782 bdev = zram->disk->part0;
1784 mutex_lock(&bdev->bd_disk->open_mutex);
1785 /* Do not reset an active device or claimed device */
1786 if (bdev->bd_openers || zram->claim) {
1787 mutex_unlock(&bdev->bd_disk->open_mutex);
1791 /* From now on, anyone can't open /dev/zram[0-9] */
1793 mutex_unlock(&bdev->bd_disk->open_mutex);
1795 /* Make sure all the pending I/O are finished */
1797 zram_reset_device(zram);
1799 mutex_lock(&bdev->bd_disk->open_mutex);
1800 zram->claim = false;
1801 mutex_unlock(&bdev->bd_disk->open_mutex);
1806 static int zram_open(struct block_device *bdev, fmode_t mode)
1811 WARN_ON(!mutex_is_locked(&bdev->bd_disk->open_mutex));
1813 zram = bdev->bd_disk->private_data;
1814 /* zram was claimed to reset so open request fails */
1821 static const struct block_device_operations zram_devops = {
1823 .submit_bio = zram_submit_bio,
1824 .swap_slot_free_notify = zram_slot_free_notify,
1825 .rw_page = zram_rw_page,
1826 .owner = THIS_MODULE
1829 static const struct block_device_operations zram_wb_devops = {
1831 .submit_bio = zram_submit_bio,
1832 .swap_slot_free_notify = zram_slot_free_notify,
1833 .owner = THIS_MODULE
1836 static DEVICE_ATTR_WO(compact);
1837 static DEVICE_ATTR_RW(disksize);
1838 static DEVICE_ATTR_RO(initstate);
1839 static DEVICE_ATTR_WO(reset);
1840 static DEVICE_ATTR_WO(mem_limit);
1841 static DEVICE_ATTR_WO(mem_used_max);
1842 static DEVICE_ATTR_WO(idle);
1843 static DEVICE_ATTR_RW(max_comp_streams);
1844 static DEVICE_ATTR_RW(comp_algorithm);
1845 #ifdef CONFIG_ZRAM_WRITEBACK
1846 static DEVICE_ATTR_RW(backing_dev);
1847 static DEVICE_ATTR_WO(writeback);
1848 static DEVICE_ATTR_RW(writeback_limit);
1849 static DEVICE_ATTR_RW(writeback_limit_enable);
1852 static struct attribute *zram_disk_attrs[] = {
1853 &dev_attr_disksize.attr,
1854 &dev_attr_initstate.attr,
1855 &dev_attr_reset.attr,
1856 &dev_attr_compact.attr,
1857 &dev_attr_mem_limit.attr,
1858 &dev_attr_mem_used_max.attr,
1859 &dev_attr_idle.attr,
1860 &dev_attr_max_comp_streams.attr,
1861 &dev_attr_comp_algorithm.attr,
1862 #ifdef CONFIG_ZRAM_WRITEBACK
1863 &dev_attr_backing_dev.attr,
1864 &dev_attr_writeback.attr,
1865 &dev_attr_writeback_limit.attr,
1866 &dev_attr_writeback_limit_enable.attr,
1868 &dev_attr_io_stat.attr,
1869 &dev_attr_mm_stat.attr,
1870 #ifdef CONFIG_ZRAM_WRITEBACK
1871 &dev_attr_bd_stat.attr,
1873 &dev_attr_debug_stat.attr,
1877 static const struct attribute_group zram_disk_attr_group = {
1878 .attrs = zram_disk_attrs,
1881 static const struct attribute_group *zram_disk_attr_groups[] = {
1882 &zram_disk_attr_group,
1887 * Allocate and initialize new zram device. the function returns
1888 * '>= 0' device_id upon success, and negative value otherwise.
1890 static int zram_add(void)
1895 zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
1899 ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
1904 init_rwsem(&zram->init_lock);
1905 #ifdef CONFIG_ZRAM_WRITEBACK
1906 spin_lock_init(&zram->wb_limit_lock);
1909 /* gendisk structure */
1910 zram->disk = blk_alloc_disk(NUMA_NO_NODE);
1912 pr_err("Error allocating disk structure for device %d\n",
1918 zram->disk->major = zram_major;
1919 zram->disk->first_minor = device_id;
1920 zram->disk->minors = 1;
1921 zram->disk->fops = &zram_devops;
1922 zram->disk->private_data = zram;
1923 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1925 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1926 set_capacity(zram->disk, 0);
1927 /* zram devices sort of resembles non-rotational disks */
1928 blk_queue_flag_set(QUEUE_FLAG_NONROT, zram->disk->queue);
1929 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1932 * To ensure that we always get PAGE_SIZE aligned
1933 * and n*PAGE_SIZED sized I/O requests.
1935 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1936 blk_queue_logical_block_size(zram->disk->queue,
1937 ZRAM_LOGICAL_BLOCK_SIZE);
1938 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1939 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1940 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1941 blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
1942 blk_queue_flag_set(QUEUE_FLAG_DISCARD, zram->disk->queue);
1945 * zram_bio_discard() will clear all logical blocks if logical block
1946 * size is identical with physical block size(PAGE_SIZE). But if it is
1947 * different, we will skip discarding some parts of logical blocks in
1948 * the part of the request range which isn't aligned to physical block
1949 * size. So we can't ensure that all discarded logical blocks are
1952 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1953 blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
1955 blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, zram->disk->queue);
1956 device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
1958 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1960 zram_debugfs_register(zram);
1961 pr_info("Added device: %s\n", zram->disk->disk_name);
1965 idr_remove(&zram_index_idr, device_id);
1971 static int zram_remove(struct zram *zram)
1973 struct block_device *bdev = zram->disk->part0;
1975 mutex_lock(&bdev->bd_disk->open_mutex);
1976 if (bdev->bd_openers || zram->claim) {
1977 mutex_unlock(&bdev->bd_disk->open_mutex);
1982 mutex_unlock(&bdev->bd_disk->open_mutex);
1984 zram_debugfs_unregister(zram);
1986 /* Make sure all the pending I/O are finished */
1988 zram_reset_device(zram);
1990 pr_info("Removed device: %s\n", zram->disk->disk_name);
1992 del_gendisk(zram->disk);
1993 blk_cleanup_disk(zram->disk);
1998 /* zram-control sysfs attributes */
2001 * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
2002 * sense that reading from this file does alter the state of your system -- it
2003 * creates a new un-initialized zram device and returns back this device's
2004 * device_id (or an error code if it fails to create a new device).
2006 static ssize_t hot_add_show(struct class *class,
2007 struct class_attribute *attr,
2012 mutex_lock(&zram_index_mutex);
2014 mutex_unlock(&zram_index_mutex);
2018 return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
2020 static struct class_attribute class_attr_hot_add =
2021 __ATTR(hot_add, 0400, hot_add_show, NULL);
2023 static ssize_t hot_remove_store(struct class *class,
2024 struct class_attribute *attr,
2031 /* dev_id is gendisk->first_minor, which is `int' */
2032 ret = kstrtoint(buf, 10, &dev_id);
2038 mutex_lock(&zram_index_mutex);
2040 zram = idr_find(&zram_index_idr, dev_id);
2042 ret = zram_remove(zram);
2044 idr_remove(&zram_index_idr, dev_id);
2049 mutex_unlock(&zram_index_mutex);
2050 return ret ? ret : count;
2052 static CLASS_ATTR_WO(hot_remove);
2054 static struct attribute *zram_control_class_attrs[] = {
2055 &class_attr_hot_add.attr,
2056 &class_attr_hot_remove.attr,
2059 ATTRIBUTE_GROUPS(zram_control_class);
2061 static struct class zram_control_class = {
2062 .name = "zram-control",
2063 .owner = THIS_MODULE,
2064 .class_groups = zram_control_class_groups,
2067 static int zram_remove_cb(int id, void *ptr, void *data)
2073 static void destroy_devices(void)
2075 class_unregister(&zram_control_class);
2076 idr_for_each(&zram_index_idr, &zram_remove_cb, NULL);
2077 zram_debugfs_destroy();
2078 idr_destroy(&zram_index_idr);
2079 unregister_blkdev(zram_major, "zram");
2080 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
2083 static int __init zram_init(void)
2087 ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
2088 zcomp_cpu_up_prepare, zcomp_cpu_dead);
2092 ret = class_register(&zram_control_class);
2094 pr_err("Unable to register zram-control class\n");
2095 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
2099 zram_debugfs_create();
2100 zram_major = register_blkdev(0, "zram");
2101 if (zram_major <= 0) {
2102 pr_err("Unable to get major number\n");
2103 class_unregister(&zram_control_class);
2104 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
2108 while (num_devices != 0) {
2109 mutex_lock(&zram_index_mutex);
2111 mutex_unlock(&zram_index_mutex);
2124 static void __exit zram_exit(void)
2129 module_init(zram_init);
2130 module_exit(zram_exit);
2132 module_param(num_devices, uint, 0);
2133 MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
2135 MODULE_LICENSE("Dual BSD/GPL");
2136 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
2137 MODULE_DESCRIPTION("Compressed RAM Block Device");