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>
39 static DEFINE_IDR(zram_index_idr);
40 /* idr index must be protected */
41 static DEFINE_MUTEX(zram_index_mutex);
43 static int zram_major;
44 static const char *default_compressor = "lzo-rle";
46 /* Module params (documentation at end) */
47 static unsigned int num_devices = 1;
49 * Pages that compress to sizes equals or greater than this are stored
50 * uncompressed in memory.
52 static size_t huge_class_size;
54 static void zram_free_page(struct zram *zram, size_t index);
55 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
56 u32 index, int offset, struct bio *bio);
59 static int zram_slot_trylock(struct zram *zram, u32 index)
61 return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].flags);
64 static void zram_slot_lock(struct zram *zram, u32 index)
66 bit_spin_lock(ZRAM_LOCK, &zram->table[index].flags);
69 static void zram_slot_unlock(struct zram *zram, u32 index)
71 bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags);
74 static inline bool init_done(struct zram *zram)
76 return zram->disksize;
79 static inline struct zram *dev_to_zram(struct device *dev)
81 return (struct zram *)dev_to_disk(dev)->private_data;
84 static unsigned long zram_get_handle(struct zram *zram, u32 index)
86 return zram->table[index].handle;
89 static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle)
91 zram->table[index].handle = handle;
94 /* flag operations require table entry bit_spin_lock() being held */
95 static bool zram_test_flag(struct zram *zram, u32 index,
96 enum zram_pageflags flag)
98 return zram->table[index].flags & BIT(flag);
101 static void zram_set_flag(struct zram *zram, u32 index,
102 enum zram_pageflags flag)
104 zram->table[index].flags |= BIT(flag);
107 static void zram_clear_flag(struct zram *zram, u32 index,
108 enum zram_pageflags flag)
110 zram->table[index].flags &= ~BIT(flag);
113 static inline void zram_set_element(struct zram *zram, u32 index,
114 unsigned long element)
116 zram->table[index].element = element;
119 static unsigned long zram_get_element(struct zram *zram, u32 index)
121 return zram->table[index].element;
124 static size_t zram_get_obj_size(struct zram *zram, u32 index)
126 return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
129 static void zram_set_obj_size(struct zram *zram,
130 u32 index, size_t size)
132 unsigned long flags = zram->table[index].flags >> ZRAM_FLAG_SHIFT;
134 zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size;
137 static inline bool zram_allocated(struct zram *zram, u32 index)
139 return zram_get_obj_size(zram, index) ||
140 zram_test_flag(zram, index, ZRAM_SAME) ||
141 zram_test_flag(zram, index, ZRAM_WB);
144 #if PAGE_SIZE != 4096
145 static inline bool is_partial_io(struct bio_vec *bvec)
147 return bvec->bv_len != PAGE_SIZE;
150 static inline bool is_partial_io(struct bio_vec *bvec)
157 * Check if request is within bounds and aligned on zram logical blocks.
159 static inline bool valid_io_request(struct zram *zram,
160 sector_t start, unsigned int size)
164 /* unaligned request */
165 if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
167 if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
170 end = start + (size >> SECTOR_SHIFT);
171 bound = zram->disksize >> SECTOR_SHIFT;
172 /* out of range range */
173 if (unlikely(start >= bound || end > bound || start > end))
176 /* I/O request is valid */
180 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
182 *index += (*offset + bvec->bv_len) / PAGE_SIZE;
183 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
186 static inline void update_used_max(struct zram *zram,
187 const unsigned long pages)
189 unsigned long old_max, cur_max;
191 old_max = atomic_long_read(&zram->stats.max_used_pages);
196 old_max = atomic_long_cmpxchg(
197 &zram->stats.max_used_pages, cur_max, pages);
198 } while (old_max != cur_max);
201 static inline void zram_fill_page(void *ptr, unsigned long len,
204 WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long)));
205 memset_l(ptr, value, len / sizeof(unsigned long));
208 static bool page_same_filled(void *ptr, unsigned long *element)
214 page = (unsigned long *)ptr;
217 for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
218 if (val != page[pos])
227 static ssize_t initstate_show(struct device *dev,
228 struct device_attribute *attr, char *buf)
231 struct zram *zram = dev_to_zram(dev);
233 down_read(&zram->init_lock);
234 val = init_done(zram);
235 up_read(&zram->init_lock);
237 return scnprintf(buf, PAGE_SIZE, "%u\n", val);
240 static ssize_t disksize_show(struct device *dev,
241 struct device_attribute *attr, char *buf)
243 struct zram *zram = dev_to_zram(dev);
245 return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize);
248 static ssize_t mem_limit_store(struct device *dev,
249 struct device_attribute *attr, const char *buf, size_t len)
253 struct zram *zram = dev_to_zram(dev);
255 limit = memparse(buf, &tmp);
256 if (buf == tmp) /* no chars parsed, invalid input */
259 down_write(&zram->init_lock);
260 zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
261 up_write(&zram->init_lock);
266 static ssize_t mem_used_max_store(struct device *dev,
267 struct device_attribute *attr, const char *buf, size_t len)
271 struct zram *zram = dev_to_zram(dev);
273 err = kstrtoul(buf, 10, &val);
277 down_read(&zram->init_lock);
278 if (init_done(zram)) {
279 atomic_long_set(&zram->stats.max_used_pages,
280 zs_get_total_pages(zram->mem_pool));
282 up_read(&zram->init_lock);
287 static ssize_t idle_store(struct device *dev,
288 struct device_attribute *attr, const char *buf, size_t len)
290 struct zram *zram = dev_to_zram(dev);
291 unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
294 if (!sysfs_streq(buf, "all"))
297 down_read(&zram->init_lock);
298 if (!init_done(zram)) {
299 up_read(&zram->init_lock);
303 for (index = 0; index < nr_pages; index++) {
305 * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race.
306 * See the comment in writeback_store.
308 zram_slot_lock(zram, index);
309 if (zram_allocated(zram, index) &&
310 !zram_test_flag(zram, index, ZRAM_UNDER_WB))
311 zram_set_flag(zram, index, ZRAM_IDLE);
312 zram_slot_unlock(zram, index);
315 up_read(&zram->init_lock);
320 #ifdef CONFIG_ZRAM_WRITEBACK
321 static ssize_t writeback_limit_enable_store(struct device *dev,
322 struct device_attribute *attr, const char *buf, size_t len)
324 struct zram *zram = dev_to_zram(dev);
326 ssize_t ret = -EINVAL;
328 if (kstrtoull(buf, 10, &val))
331 down_read(&zram->init_lock);
332 spin_lock(&zram->wb_limit_lock);
333 zram->wb_limit_enable = val;
334 spin_unlock(&zram->wb_limit_lock);
335 up_read(&zram->init_lock);
341 static ssize_t writeback_limit_enable_show(struct device *dev,
342 struct device_attribute *attr, char *buf)
345 struct zram *zram = dev_to_zram(dev);
347 down_read(&zram->init_lock);
348 spin_lock(&zram->wb_limit_lock);
349 val = zram->wb_limit_enable;
350 spin_unlock(&zram->wb_limit_lock);
351 up_read(&zram->init_lock);
353 return scnprintf(buf, PAGE_SIZE, "%d\n", val);
356 static ssize_t writeback_limit_store(struct device *dev,
357 struct device_attribute *attr, const char *buf, size_t len)
359 struct zram *zram = dev_to_zram(dev);
361 ssize_t ret = -EINVAL;
363 if (kstrtoull(buf, 10, &val))
366 down_read(&zram->init_lock);
367 spin_lock(&zram->wb_limit_lock);
368 zram->bd_wb_limit = val;
369 spin_unlock(&zram->wb_limit_lock);
370 up_read(&zram->init_lock);
376 static ssize_t writeback_limit_show(struct device *dev,
377 struct device_attribute *attr, char *buf)
380 struct zram *zram = dev_to_zram(dev);
382 down_read(&zram->init_lock);
383 spin_lock(&zram->wb_limit_lock);
384 val = zram->bd_wb_limit;
385 spin_unlock(&zram->wb_limit_lock);
386 up_read(&zram->init_lock);
388 return scnprintf(buf, PAGE_SIZE, "%llu\n", val);
391 static void reset_bdev(struct zram *zram)
393 struct block_device *bdev;
395 if (!zram->backing_dev)
399 if (zram->old_block_size)
400 set_blocksize(bdev, zram->old_block_size);
401 blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
402 /* hope filp_close flush all of IO */
403 filp_close(zram->backing_dev, NULL);
404 zram->backing_dev = NULL;
405 zram->old_block_size = 0;
407 zram->disk->queue->backing_dev_info->capabilities |=
408 BDI_CAP_SYNCHRONOUS_IO;
409 kvfree(zram->bitmap);
413 static ssize_t backing_dev_show(struct device *dev,
414 struct device_attribute *attr, char *buf)
416 struct zram *zram = dev_to_zram(dev);
417 struct file *file = zram->backing_dev;
421 down_read(&zram->init_lock);
422 if (!zram->backing_dev) {
423 memcpy(buf, "none\n", 5);
424 up_read(&zram->init_lock);
428 p = file_path(file, buf, PAGE_SIZE - 1);
435 memmove(buf, p, ret);
438 up_read(&zram->init_lock);
442 static ssize_t backing_dev_store(struct device *dev,
443 struct device_attribute *attr, const char *buf, size_t len)
447 struct file *backing_dev = NULL;
449 struct address_space *mapping;
450 unsigned int bitmap_sz, old_block_size = 0;
451 unsigned long nr_pages, *bitmap = NULL;
452 struct block_device *bdev = NULL;
454 struct zram *zram = dev_to_zram(dev);
456 file_name = kmalloc(PATH_MAX, GFP_KERNEL);
460 down_write(&zram->init_lock);
461 if (init_done(zram)) {
462 pr_info("Can't setup backing device for initialized device\n");
467 strlcpy(file_name, buf, PATH_MAX);
468 /* ignore trailing newline */
469 sz = strlen(file_name);
470 if (sz > 0 && file_name[sz - 1] == '\n')
471 file_name[sz - 1] = 0x00;
473 backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);
474 if (IS_ERR(backing_dev)) {
475 err = PTR_ERR(backing_dev);
480 mapping = backing_dev->f_mapping;
481 inode = mapping->host;
483 /* Support only block device in this moment */
484 if (!S_ISBLK(inode->i_mode)) {
489 bdev = bdgrab(I_BDEV(inode));
490 err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram);
496 nr_pages = i_size_read(inode) >> PAGE_SHIFT;
497 bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long);
498 bitmap = kvzalloc(bitmap_sz, GFP_KERNEL);
504 old_block_size = block_size(bdev);
505 err = set_blocksize(bdev, PAGE_SIZE);
511 zram->old_block_size = old_block_size;
513 zram->backing_dev = backing_dev;
514 zram->bitmap = bitmap;
515 zram->nr_pages = nr_pages;
517 * With writeback feature, zram does asynchronous IO so it's no longer
518 * synchronous device so let's remove synchronous io flag. Othewise,
519 * upper layer(e.g., swap) could wait IO completion rather than
520 * (submit and return), which will cause system sluggish.
521 * Furthermore, when the IO function returns(e.g., swap_readpage),
522 * upper layer expects IO was done so it could deallocate the page
523 * freely but in fact, IO is going on so finally could cause
524 * use-after-free when the IO is really done.
526 zram->disk->queue->backing_dev_info->capabilities &=
527 ~BDI_CAP_SYNCHRONOUS_IO;
528 up_write(&zram->init_lock);
530 pr_info("setup backing device %s\n", file_name);
539 blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
542 filp_close(backing_dev, NULL);
544 up_write(&zram->init_lock);
551 static unsigned long alloc_block_bdev(struct zram *zram)
553 unsigned long blk_idx = 1;
555 /* skip 0 bit to confuse zram.handle = 0 */
556 blk_idx = find_next_zero_bit(zram->bitmap, zram->nr_pages, blk_idx);
557 if (blk_idx == zram->nr_pages)
560 if (test_and_set_bit(blk_idx, zram->bitmap))
563 atomic64_inc(&zram->stats.bd_count);
567 static void free_block_bdev(struct zram *zram, unsigned long blk_idx)
571 was_set = test_and_clear_bit(blk_idx, zram->bitmap);
572 WARN_ON_ONCE(!was_set);
573 atomic64_dec(&zram->stats.bd_count);
576 static void zram_page_end_io(struct bio *bio)
578 struct page *page = bio_first_page_all(bio);
580 page_endio(page, op_is_write(bio_op(bio)),
581 blk_status_to_errno(bio->bi_status));
586 * Returns 1 if the submission is successful.
588 static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
589 unsigned long entry, struct bio *parent)
593 bio = bio_alloc(GFP_ATOMIC, 1);
597 bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9);
598 bio_set_dev(bio, zram->bdev);
599 if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, bvec->bv_offset)) {
605 bio->bi_opf = REQ_OP_READ;
606 bio->bi_end_io = zram_page_end_io;
608 bio->bi_opf = parent->bi_opf;
609 bio_chain(bio, parent);
616 #define HUGE_WRITEBACK 1
617 #define IDLE_WRITEBACK 2
619 static ssize_t writeback_store(struct device *dev,
620 struct device_attribute *attr, const char *buf, size_t len)
622 struct zram *zram = dev_to_zram(dev);
623 unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
626 struct bio_vec bio_vec;
630 unsigned long blk_idx = 0;
632 if (sysfs_streq(buf, "idle"))
633 mode = IDLE_WRITEBACK;
634 else if (sysfs_streq(buf, "huge"))
635 mode = HUGE_WRITEBACK;
639 down_read(&zram->init_lock);
640 if (!init_done(zram)) {
642 goto release_init_lock;
645 if (!zram->backing_dev) {
647 goto release_init_lock;
650 page = alloc_page(GFP_KERNEL);
653 goto release_init_lock;
656 for (index = 0; index < nr_pages; index++) {
660 bvec.bv_len = PAGE_SIZE;
663 spin_lock(&zram->wb_limit_lock);
664 if (zram->wb_limit_enable && !zram->bd_wb_limit) {
665 spin_unlock(&zram->wb_limit_lock);
669 spin_unlock(&zram->wb_limit_lock);
672 blk_idx = alloc_block_bdev(zram);
679 zram_slot_lock(zram, index);
680 if (!zram_allocated(zram, index))
683 if (zram_test_flag(zram, index, ZRAM_WB) ||
684 zram_test_flag(zram, index, ZRAM_SAME) ||
685 zram_test_flag(zram, index, ZRAM_UNDER_WB))
688 if (mode == IDLE_WRITEBACK &&
689 !zram_test_flag(zram, index, ZRAM_IDLE))
691 if (mode == HUGE_WRITEBACK &&
692 !zram_test_flag(zram, index, ZRAM_HUGE))
695 * Clearing ZRAM_UNDER_WB is duty of caller.
696 * IOW, zram_free_page never clear it.
698 zram_set_flag(zram, index, ZRAM_UNDER_WB);
699 /* Need for hugepage writeback racing */
700 zram_set_flag(zram, index, ZRAM_IDLE);
701 zram_slot_unlock(zram, index);
702 if (zram_bvec_read(zram, &bvec, index, 0, NULL)) {
703 zram_slot_lock(zram, index);
704 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
705 zram_clear_flag(zram, index, ZRAM_IDLE);
706 zram_slot_unlock(zram, index);
710 bio_init(&bio, &bio_vec, 1);
711 bio_set_dev(&bio, zram->bdev);
712 bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9);
713 bio.bi_opf = REQ_OP_WRITE | REQ_SYNC;
715 bio_add_page(&bio, bvec.bv_page, bvec.bv_len,
718 * XXX: A single page IO would be inefficient for write
719 * but it would be not bad as starter.
721 ret = submit_bio_wait(&bio);
723 zram_slot_lock(zram, index);
724 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
725 zram_clear_flag(zram, index, ZRAM_IDLE);
726 zram_slot_unlock(zram, index);
730 atomic64_inc(&zram->stats.bd_writes);
732 * We released zram_slot_lock so need to check if the slot was
733 * changed. If there is freeing for the slot, we can catch it
734 * easily by zram_allocated.
735 * A subtle case is the slot is freed/reallocated/marked as
736 * ZRAM_IDLE again. To close the race, idle_store doesn't
737 * mark ZRAM_IDLE once it found the slot was ZRAM_UNDER_WB.
738 * Thus, we could close the race by checking ZRAM_IDLE bit.
740 zram_slot_lock(zram, index);
741 if (!zram_allocated(zram, index) ||
742 !zram_test_flag(zram, index, ZRAM_IDLE)) {
743 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
744 zram_clear_flag(zram, index, ZRAM_IDLE);
748 zram_free_page(zram, index);
749 zram_clear_flag(zram, index, ZRAM_UNDER_WB);
750 zram_set_flag(zram, index, ZRAM_WB);
751 zram_set_element(zram, index, blk_idx);
753 atomic64_inc(&zram->stats.pages_stored);
754 spin_lock(&zram->wb_limit_lock);
755 if (zram->wb_limit_enable && zram->bd_wb_limit > 0)
756 zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12);
757 spin_unlock(&zram->wb_limit_lock);
759 zram_slot_unlock(zram, index);
763 free_block_bdev(zram, blk_idx);
767 up_read(&zram->init_lock);
773 struct work_struct work;
779 #if PAGE_SIZE != 4096
780 static void zram_sync_read(struct work_struct *work)
783 struct zram_work *zw = container_of(work, struct zram_work, work);
784 struct zram *zram = zw->zram;
785 unsigned long entry = zw->entry;
786 struct bio *bio = zw->bio;
788 read_from_bdev_async(zram, &bvec, entry, bio);
792 * Block layer want one ->make_request_fn to be active at a time
793 * so if we use chained IO with parent IO in same context,
794 * it's a deadlock. To avoid, it, it uses worker thread context.
796 static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec,
797 unsigned long entry, struct bio *bio)
799 struct zram_work work;
805 INIT_WORK_ONSTACK(&work.work, zram_sync_read);
806 queue_work(system_unbound_wq, &work.work);
807 flush_work(&work.work);
808 destroy_work_on_stack(&work.work);
813 static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec,
814 unsigned long entry, struct bio *bio)
821 static int read_from_bdev(struct zram *zram, struct bio_vec *bvec,
822 unsigned long entry, struct bio *parent, bool sync)
824 atomic64_inc(&zram->stats.bd_reads);
826 return read_from_bdev_sync(zram, bvec, entry, parent);
828 return read_from_bdev_async(zram, bvec, entry, parent);
831 static inline void reset_bdev(struct zram *zram) {};
832 static int read_from_bdev(struct zram *zram, struct bio_vec *bvec,
833 unsigned long entry, struct bio *parent, bool sync)
838 static void free_block_bdev(struct zram *zram, unsigned long blk_idx) {};
841 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
843 static struct dentry *zram_debugfs_root;
845 static void zram_debugfs_create(void)
847 zram_debugfs_root = debugfs_create_dir("zram", NULL);
850 static void zram_debugfs_destroy(void)
852 debugfs_remove_recursive(zram_debugfs_root);
855 static void zram_accessed(struct zram *zram, u32 index)
857 zram_clear_flag(zram, index, ZRAM_IDLE);
858 zram->table[index].ac_time = ktime_get_boottime();
861 static ssize_t read_block_state(struct file *file, char __user *buf,
862 size_t count, loff_t *ppos)
865 ssize_t index, written = 0;
866 struct zram *zram = file->private_data;
867 unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
868 struct timespec64 ts;
870 kbuf = kvmalloc(count, GFP_KERNEL);
874 down_read(&zram->init_lock);
875 if (!init_done(zram)) {
876 up_read(&zram->init_lock);
881 for (index = *ppos; index < nr_pages; index++) {
884 zram_slot_lock(zram, index);
885 if (!zram_allocated(zram, index))
888 ts = ktime_to_timespec64(zram->table[index].ac_time);
889 copied = snprintf(kbuf + written, count,
890 "%12zd %12lld.%06lu %c%c%c%c\n",
891 index, (s64)ts.tv_sec,
892 ts.tv_nsec / NSEC_PER_USEC,
893 zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.',
894 zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.',
895 zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.',
896 zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.');
898 if (count < copied) {
899 zram_slot_unlock(zram, index);
905 zram_slot_unlock(zram, index);
909 up_read(&zram->init_lock);
910 if (copy_to_user(buf, kbuf, written))
917 static const struct file_operations proc_zram_block_state_op = {
919 .read = read_block_state,
920 .llseek = default_llseek,
923 static void zram_debugfs_register(struct zram *zram)
925 if (!zram_debugfs_root)
928 zram->debugfs_dir = debugfs_create_dir(zram->disk->disk_name,
930 debugfs_create_file("block_state", 0400, zram->debugfs_dir,
931 zram, &proc_zram_block_state_op);
934 static void zram_debugfs_unregister(struct zram *zram)
936 debugfs_remove_recursive(zram->debugfs_dir);
939 static void zram_debugfs_create(void) {};
940 static void zram_debugfs_destroy(void) {};
941 static void zram_accessed(struct zram *zram, u32 index)
943 zram_clear_flag(zram, index, ZRAM_IDLE);
945 static void zram_debugfs_register(struct zram *zram) {};
946 static void zram_debugfs_unregister(struct zram *zram) {};
950 * We switched to per-cpu streams and this attr is not needed anymore.
951 * However, we will keep it around for some time, because:
952 * a) we may revert per-cpu streams in the future
953 * b) it's visible to user space and we need to follow our 2 years
954 * retirement rule; but we already have a number of 'soon to be
955 * altered' attrs, so max_comp_streams need to wait for the next
958 static ssize_t max_comp_streams_show(struct device *dev,
959 struct device_attribute *attr, char *buf)
961 return scnprintf(buf, PAGE_SIZE, "%d\n", num_online_cpus());
964 static ssize_t max_comp_streams_store(struct device *dev,
965 struct device_attribute *attr, const char *buf, size_t len)
970 static ssize_t comp_algorithm_show(struct device *dev,
971 struct device_attribute *attr, char *buf)
974 struct zram *zram = dev_to_zram(dev);
976 down_read(&zram->init_lock);
977 sz = zcomp_available_show(zram->compressor, buf);
978 up_read(&zram->init_lock);
983 static ssize_t comp_algorithm_store(struct device *dev,
984 struct device_attribute *attr, const char *buf, size_t len)
986 struct zram *zram = dev_to_zram(dev);
987 char compressor[ARRAY_SIZE(zram->compressor)];
990 strlcpy(compressor, buf, sizeof(compressor));
991 /* ignore trailing newline */
992 sz = strlen(compressor);
993 if (sz > 0 && compressor[sz - 1] == '\n')
994 compressor[sz - 1] = 0x00;
996 if (!zcomp_available_algorithm(compressor))
999 down_write(&zram->init_lock);
1000 if (init_done(zram)) {
1001 up_write(&zram->init_lock);
1002 pr_info("Can't change algorithm for initialized device\n");
1006 strcpy(zram->compressor, compressor);
1007 up_write(&zram->init_lock);
1011 static ssize_t compact_store(struct device *dev,
1012 struct device_attribute *attr, const char *buf, size_t len)
1014 struct zram *zram = dev_to_zram(dev);
1016 down_read(&zram->init_lock);
1017 if (!init_done(zram)) {
1018 up_read(&zram->init_lock);
1022 zs_compact(zram->mem_pool);
1023 up_read(&zram->init_lock);
1028 static ssize_t io_stat_show(struct device *dev,
1029 struct device_attribute *attr, char *buf)
1031 struct zram *zram = dev_to_zram(dev);
1034 down_read(&zram->init_lock);
1035 ret = scnprintf(buf, PAGE_SIZE,
1036 "%8llu %8llu %8llu %8llu\n",
1037 (u64)atomic64_read(&zram->stats.failed_reads),
1038 (u64)atomic64_read(&zram->stats.failed_writes),
1039 (u64)atomic64_read(&zram->stats.invalid_io),
1040 (u64)atomic64_read(&zram->stats.notify_free));
1041 up_read(&zram->init_lock);
1046 static ssize_t mm_stat_show(struct device *dev,
1047 struct device_attribute *attr, char *buf)
1049 struct zram *zram = dev_to_zram(dev);
1050 struct zs_pool_stats pool_stats;
1051 u64 orig_size, mem_used = 0;
1055 memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats));
1057 down_read(&zram->init_lock);
1058 if (init_done(zram)) {
1059 mem_used = zs_get_total_pages(zram->mem_pool);
1060 zs_pool_stats(zram->mem_pool, &pool_stats);
1063 orig_size = atomic64_read(&zram->stats.pages_stored);
1064 max_used = atomic_long_read(&zram->stats.max_used_pages);
1066 ret = scnprintf(buf, PAGE_SIZE,
1067 "%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu\n",
1068 orig_size << PAGE_SHIFT,
1069 (u64)atomic64_read(&zram->stats.compr_data_size),
1070 mem_used << PAGE_SHIFT,
1071 zram->limit_pages << PAGE_SHIFT,
1072 max_used << PAGE_SHIFT,
1073 (u64)atomic64_read(&zram->stats.same_pages),
1074 pool_stats.pages_compacted,
1075 (u64)atomic64_read(&zram->stats.huge_pages));
1076 up_read(&zram->init_lock);
1081 #ifdef CONFIG_ZRAM_WRITEBACK
1082 #define FOUR_K(x) ((x) * (1 << (PAGE_SHIFT - 12)))
1083 static ssize_t bd_stat_show(struct device *dev,
1084 struct device_attribute *attr, char *buf)
1086 struct zram *zram = dev_to_zram(dev);
1089 down_read(&zram->init_lock);
1090 ret = scnprintf(buf, PAGE_SIZE,
1091 "%8llu %8llu %8llu\n",
1092 FOUR_K((u64)atomic64_read(&zram->stats.bd_count)),
1093 FOUR_K((u64)atomic64_read(&zram->stats.bd_reads)),
1094 FOUR_K((u64)atomic64_read(&zram->stats.bd_writes)));
1095 up_read(&zram->init_lock);
1101 static ssize_t debug_stat_show(struct device *dev,
1102 struct device_attribute *attr, char *buf)
1105 struct zram *zram = dev_to_zram(dev);
1108 down_read(&zram->init_lock);
1109 ret = scnprintf(buf, PAGE_SIZE,
1110 "version: %d\n%8llu %8llu\n",
1112 (u64)atomic64_read(&zram->stats.writestall),
1113 (u64)atomic64_read(&zram->stats.miss_free));
1114 up_read(&zram->init_lock);
1119 static DEVICE_ATTR_RO(io_stat);
1120 static DEVICE_ATTR_RO(mm_stat);
1121 #ifdef CONFIG_ZRAM_WRITEBACK
1122 static DEVICE_ATTR_RO(bd_stat);
1124 static DEVICE_ATTR_RO(debug_stat);
1126 static void zram_meta_free(struct zram *zram, u64 disksize)
1128 size_t num_pages = disksize >> PAGE_SHIFT;
1131 /* Free all pages that are still in this zram device */
1132 for (index = 0; index < num_pages; index++)
1133 zram_free_page(zram, index);
1135 zs_destroy_pool(zram->mem_pool);
1139 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
1143 num_pages = disksize >> PAGE_SHIFT;
1144 zram->table = vzalloc(array_size(num_pages, sizeof(*zram->table)));
1148 zram->mem_pool = zs_create_pool(zram->disk->disk_name);
1149 if (!zram->mem_pool) {
1154 if (!huge_class_size)
1155 huge_class_size = zs_huge_class_size(zram->mem_pool);
1160 * To protect concurrent access to the same index entry,
1161 * caller should hold this table index entry's bit_spinlock to
1162 * indicate this index entry is accessing.
1164 static void zram_free_page(struct zram *zram, size_t index)
1166 unsigned long handle;
1168 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
1169 zram->table[index].ac_time = 0;
1171 if (zram_test_flag(zram, index, ZRAM_IDLE))
1172 zram_clear_flag(zram, index, ZRAM_IDLE);
1174 if (zram_test_flag(zram, index, ZRAM_HUGE)) {
1175 zram_clear_flag(zram, index, ZRAM_HUGE);
1176 atomic64_dec(&zram->stats.huge_pages);
1179 if (zram_test_flag(zram, index, ZRAM_WB)) {
1180 zram_clear_flag(zram, index, ZRAM_WB);
1181 free_block_bdev(zram, zram_get_element(zram, index));
1186 * No memory is allocated for same element filled pages.
1187 * Simply clear same page flag.
1189 if (zram_test_flag(zram, index, ZRAM_SAME)) {
1190 zram_clear_flag(zram, index, ZRAM_SAME);
1191 atomic64_dec(&zram->stats.same_pages);
1195 handle = zram_get_handle(zram, index);
1199 zs_free(zram->mem_pool, handle);
1201 atomic64_sub(zram_get_obj_size(zram, index),
1202 &zram->stats.compr_data_size);
1204 atomic64_dec(&zram->stats.pages_stored);
1205 zram_set_handle(zram, index, 0);
1206 zram_set_obj_size(zram, index, 0);
1207 WARN_ON_ONCE(zram->table[index].flags &
1208 ~(1UL << ZRAM_LOCK | 1UL << ZRAM_UNDER_WB));
1211 static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
1212 struct bio *bio, bool partial_io)
1215 unsigned long handle;
1219 zram_slot_lock(zram, index);
1220 if (zram_test_flag(zram, index, ZRAM_WB)) {
1221 struct bio_vec bvec;
1223 zram_slot_unlock(zram, index);
1225 bvec.bv_page = page;
1226 bvec.bv_len = PAGE_SIZE;
1228 return read_from_bdev(zram, &bvec,
1229 zram_get_element(zram, index),
1233 handle = zram_get_handle(zram, index);
1234 if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) {
1235 unsigned long value;
1238 value = handle ? zram_get_element(zram, index) : 0;
1239 mem = kmap_atomic(page);
1240 zram_fill_page(mem, PAGE_SIZE, value);
1242 zram_slot_unlock(zram, index);
1246 size = zram_get_obj_size(zram, index);
1248 src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
1249 if (size == PAGE_SIZE) {
1250 dst = kmap_atomic(page);
1251 memcpy(dst, src, PAGE_SIZE);
1255 struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp);
1257 dst = kmap_atomic(page);
1258 ret = zcomp_decompress(zstrm, src, size, dst);
1260 zcomp_stream_put(zram->comp);
1262 zs_unmap_object(zram->mem_pool, handle);
1263 zram_slot_unlock(zram, index);
1265 /* Should NEVER happen. Return bio error if it does. */
1267 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
1272 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
1273 u32 index, int offset, struct bio *bio)
1278 page = bvec->bv_page;
1279 if (is_partial_io(bvec)) {
1280 /* Use a temporary buffer to decompress the page */
1281 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
1286 ret = __zram_bvec_read(zram, page, index, bio, is_partial_io(bvec));
1290 if (is_partial_io(bvec)) {
1291 void *dst = kmap_atomic(bvec->bv_page);
1292 void *src = kmap_atomic(page);
1294 memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len);
1299 if (is_partial_io(bvec))
1305 static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
1306 u32 index, struct bio *bio)
1309 unsigned long alloced_pages;
1310 unsigned long handle = 0;
1311 unsigned int comp_len = 0;
1312 void *src, *dst, *mem;
1313 struct zcomp_strm *zstrm;
1314 struct page *page = bvec->bv_page;
1315 unsigned long element = 0;
1316 enum zram_pageflags flags = 0;
1318 mem = kmap_atomic(page);
1319 if (page_same_filled(mem, &element)) {
1321 /* Free memory associated with this sector now. */
1323 atomic64_inc(&zram->stats.same_pages);
1329 zstrm = zcomp_stream_get(zram->comp);
1330 src = kmap_atomic(page);
1331 ret = zcomp_compress(zstrm, src, &comp_len);
1334 if (unlikely(ret)) {
1335 zcomp_stream_put(zram->comp);
1336 pr_err("Compression failed! err=%d\n", ret);
1337 zs_free(zram->mem_pool, handle);
1341 if (comp_len >= huge_class_size)
1342 comp_len = PAGE_SIZE;
1344 * handle allocation has 2 paths:
1345 * a) fast path is executed with preemption disabled (for
1346 * per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear,
1347 * since we can't sleep;
1348 * b) slow path enables preemption and attempts to allocate
1349 * the page with __GFP_DIRECT_RECLAIM bit set. we have to
1350 * put per-cpu compression stream and, thus, to re-do
1351 * the compression once handle is allocated.
1353 * if we have a 'non-null' handle here then we are coming
1354 * from the slow path and handle has already been allocated.
1357 handle = zs_malloc(zram->mem_pool, comp_len,
1358 __GFP_KSWAPD_RECLAIM |
1363 zcomp_stream_put(zram->comp);
1364 atomic64_inc(&zram->stats.writestall);
1365 handle = zs_malloc(zram->mem_pool, comp_len,
1366 GFP_NOIO | __GFP_HIGHMEM |
1369 goto compress_again;
1373 alloced_pages = zs_get_total_pages(zram->mem_pool);
1374 update_used_max(zram, alloced_pages);
1376 if (zram->limit_pages && alloced_pages > zram->limit_pages) {
1377 zcomp_stream_put(zram->comp);
1378 zs_free(zram->mem_pool, handle);
1382 dst = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
1384 src = zstrm->buffer;
1385 if (comp_len == PAGE_SIZE)
1386 src = kmap_atomic(page);
1387 memcpy(dst, src, comp_len);
1388 if (comp_len == PAGE_SIZE)
1391 zcomp_stream_put(zram->comp);
1392 zs_unmap_object(zram->mem_pool, handle);
1393 atomic64_add(comp_len, &zram->stats.compr_data_size);
1396 * Free memory associated with this sector
1397 * before overwriting unused sectors.
1399 zram_slot_lock(zram, index);
1400 zram_free_page(zram, index);
1402 if (comp_len == PAGE_SIZE) {
1403 zram_set_flag(zram, index, ZRAM_HUGE);
1404 atomic64_inc(&zram->stats.huge_pages);
1408 zram_set_flag(zram, index, flags);
1409 zram_set_element(zram, index, element);
1411 zram_set_handle(zram, index, handle);
1412 zram_set_obj_size(zram, index, comp_len);
1414 zram_slot_unlock(zram, index);
1417 atomic64_inc(&zram->stats.pages_stored);
1421 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
1422 u32 index, int offset, struct bio *bio)
1425 struct page *page = NULL;
1430 if (is_partial_io(bvec)) {
1433 * This is a partial IO. We need to read the full page
1434 * before to write the changes.
1436 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
1440 ret = __zram_bvec_read(zram, page, index, bio, true);
1444 src = kmap_atomic(bvec->bv_page);
1445 dst = kmap_atomic(page);
1446 memcpy(dst + offset, src + bvec->bv_offset, bvec->bv_len);
1451 vec.bv_len = PAGE_SIZE;
1455 ret = __zram_bvec_write(zram, &vec, index, bio);
1457 if (is_partial_io(bvec))
1463 * zram_bio_discard - handler on discard request
1464 * @index: physical block index in PAGE_SIZE units
1465 * @offset: byte offset within physical block
1467 static void zram_bio_discard(struct zram *zram, u32 index,
1468 int offset, struct bio *bio)
1470 size_t n = bio->bi_iter.bi_size;
1473 * zram manages data in physical block size units. Because logical block
1474 * size isn't identical with physical block size on some arch, we
1475 * could get a discard request pointing to a specific offset within a
1476 * certain physical block. Although we can handle this request by
1477 * reading that physiclal block and decompressing and partially zeroing
1478 * and re-compressing and then re-storing it, this isn't reasonable
1479 * because our intent with a discard request is to save memory. So
1480 * skipping this logical block is appropriate here.
1483 if (n <= (PAGE_SIZE - offset))
1486 n -= (PAGE_SIZE - offset);
1490 while (n >= PAGE_SIZE) {
1491 zram_slot_lock(zram, index);
1492 zram_free_page(zram, index);
1493 zram_slot_unlock(zram, index);
1494 atomic64_inc(&zram->stats.notify_free);
1501 * Returns errno if it has some problem. Otherwise return 0 or 1.
1502 * Returns 0 if IO request was done synchronously
1503 * Returns 1 if IO request was successfully submitted.
1505 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
1506 int offset, unsigned int op, struct bio *bio)
1508 unsigned long start_time = jiffies;
1509 struct request_queue *q = zram->disk->queue;
1512 generic_start_io_acct(q, op, bvec->bv_len >> SECTOR_SHIFT,
1513 &zram->disk->part0);
1515 if (!op_is_write(op)) {
1516 atomic64_inc(&zram->stats.num_reads);
1517 ret = zram_bvec_read(zram, bvec, index, offset, bio);
1518 flush_dcache_page(bvec->bv_page);
1520 atomic64_inc(&zram->stats.num_writes);
1521 ret = zram_bvec_write(zram, bvec, index, offset, bio);
1524 generic_end_io_acct(q, op, &zram->disk->part0, start_time);
1526 zram_slot_lock(zram, index);
1527 zram_accessed(zram, index);
1528 zram_slot_unlock(zram, index);
1530 if (unlikely(ret < 0)) {
1531 if (!op_is_write(op))
1532 atomic64_inc(&zram->stats.failed_reads);
1534 atomic64_inc(&zram->stats.failed_writes);
1540 static void __zram_make_request(struct zram *zram, struct bio *bio)
1544 struct bio_vec bvec;
1545 struct bvec_iter iter;
1547 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
1548 offset = (bio->bi_iter.bi_sector &
1549 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
1551 switch (bio_op(bio)) {
1552 case REQ_OP_DISCARD:
1553 case REQ_OP_WRITE_ZEROES:
1554 zram_bio_discard(zram, index, offset, bio);
1561 bio_for_each_segment(bvec, bio, iter) {
1562 struct bio_vec bv = bvec;
1563 unsigned int unwritten = bvec.bv_len;
1566 bv.bv_len = min_t(unsigned int, PAGE_SIZE - offset,
1568 if (zram_bvec_rw(zram, &bv, index, offset,
1569 bio_op(bio), bio) < 0)
1572 bv.bv_offset += bv.bv_len;
1573 unwritten -= bv.bv_len;
1575 update_position(&index, &offset, &bv);
1576 } while (unwritten);
1587 * Handler function for all zram I/O requests.
1589 static blk_qc_t zram_make_request(struct request_queue *queue, struct bio *bio)
1591 struct zram *zram = queue->queuedata;
1593 if (!valid_io_request(zram, bio->bi_iter.bi_sector,
1594 bio->bi_iter.bi_size)) {
1595 atomic64_inc(&zram->stats.invalid_io);
1599 __zram_make_request(zram, bio);
1600 return BLK_QC_T_NONE;
1604 return BLK_QC_T_NONE;
1607 static void zram_slot_free_notify(struct block_device *bdev,
1608 unsigned long index)
1612 zram = bdev->bd_disk->private_data;
1614 atomic64_inc(&zram->stats.notify_free);
1615 if (!zram_slot_trylock(zram, index)) {
1616 atomic64_inc(&zram->stats.miss_free);
1620 zram_free_page(zram, index);
1621 zram_slot_unlock(zram, index);
1624 static int zram_rw_page(struct block_device *bdev, sector_t sector,
1625 struct page *page, unsigned int op)
1632 if (PageTransHuge(page))
1634 zram = bdev->bd_disk->private_data;
1636 if (!valid_io_request(zram, sector, PAGE_SIZE)) {
1637 atomic64_inc(&zram->stats.invalid_io);
1642 index = sector >> SECTORS_PER_PAGE_SHIFT;
1643 offset = (sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
1646 bv.bv_len = PAGE_SIZE;
1649 ret = zram_bvec_rw(zram, &bv, index, offset, op, NULL);
1652 * If I/O fails, just return error(ie, non-zero) without
1653 * calling page_endio.
1654 * It causes resubmit the I/O with bio request by upper functions
1655 * of rw_page(e.g., swap_readpage, __swap_writepage) and
1656 * bio->bi_end_io does things to handle the error
1657 * (e.g., SetPageError, set_page_dirty and extra works).
1659 if (unlikely(ret < 0))
1664 page_endio(page, op_is_write(op), 0);
1675 static void zram_reset_device(struct zram *zram)
1680 down_write(&zram->init_lock);
1682 zram->limit_pages = 0;
1684 if (!init_done(zram)) {
1685 up_write(&zram->init_lock);
1690 disksize = zram->disksize;
1693 set_capacity(zram->disk, 0);
1694 part_stat_set_all(&zram->disk->part0, 0);
1696 up_write(&zram->init_lock);
1697 /* I/O operation under all of CPU are done so let's free */
1698 zram_meta_free(zram, disksize);
1699 memset(&zram->stats, 0, sizeof(zram->stats));
1700 zcomp_destroy(comp);
1704 static ssize_t disksize_store(struct device *dev,
1705 struct device_attribute *attr, const char *buf, size_t len)
1709 struct zram *zram = dev_to_zram(dev);
1712 disksize = memparse(buf, NULL);
1716 down_write(&zram->init_lock);
1717 if (init_done(zram)) {
1718 pr_info("Cannot change disksize for initialized device\n");
1723 disksize = PAGE_ALIGN(disksize);
1724 if (!zram_meta_alloc(zram, disksize)) {
1729 comp = zcomp_create(zram->compressor);
1731 pr_err("Cannot initialise %s compressing backend\n",
1733 err = PTR_ERR(comp);
1738 zram->disksize = disksize;
1739 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
1741 revalidate_disk(zram->disk);
1742 up_write(&zram->init_lock);
1747 zram_meta_free(zram, disksize);
1749 up_write(&zram->init_lock);
1753 static ssize_t reset_store(struct device *dev,
1754 struct device_attribute *attr, const char *buf, size_t len)
1757 unsigned short do_reset;
1759 struct block_device *bdev;
1761 ret = kstrtou16(buf, 10, &do_reset);
1768 zram = dev_to_zram(dev);
1769 bdev = bdget_disk(zram->disk, 0);
1773 mutex_lock(&bdev->bd_mutex);
1774 /* Do not reset an active device or claimed device */
1775 if (bdev->bd_openers || zram->claim) {
1776 mutex_unlock(&bdev->bd_mutex);
1781 /* From now on, anyone can't open /dev/zram[0-9] */
1783 mutex_unlock(&bdev->bd_mutex);
1785 /* Make sure all the pending I/O are finished */
1787 zram_reset_device(zram);
1788 revalidate_disk(zram->disk);
1791 mutex_lock(&bdev->bd_mutex);
1792 zram->claim = false;
1793 mutex_unlock(&bdev->bd_mutex);
1798 static int zram_open(struct block_device *bdev, fmode_t mode)
1803 WARN_ON(!mutex_is_locked(&bdev->bd_mutex));
1805 zram = bdev->bd_disk->private_data;
1806 /* zram was claimed to reset so open request fails */
1813 static const struct block_device_operations zram_devops = {
1815 .swap_slot_free_notify = zram_slot_free_notify,
1816 .rw_page = zram_rw_page,
1817 .owner = THIS_MODULE
1820 static DEVICE_ATTR_WO(compact);
1821 static DEVICE_ATTR_RW(disksize);
1822 static DEVICE_ATTR_RO(initstate);
1823 static DEVICE_ATTR_WO(reset);
1824 static DEVICE_ATTR_WO(mem_limit);
1825 static DEVICE_ATTR_WO(mem_used_max);
1826 static DEVICE_ATTR_WO(idle);
1827 static DEVICE_ATTR_RW(max_comp_streams);
1828 static DEVICE_ATTR_RW(comp_algorithm);
1829 #ifdef CONFIG_ZRAM_WRITEBACK
1830 static DEVICE_ATTR_RW(backing_dev);
1831 static DEVICE_ATTR_WO(writeback);
1832 static DEVICE_ATTR_RW(writeback_limit);
1833 static DEVICE_ATTR_RW(writeback_limit_enable);
1836 static struct attribute *zram_disk_attrs[] = {
1837 &dev_attr_disksize.attr,
1838 &dev_attr_initstate.attr,
1839 &dev_attr_reset.attr,
1840 &dev_attr_compact.attr,
1841 &dev_attr_mem_limit.attr,
1842 &dev_attr_mem_used_max.attr,
1843 &dev_attr_idle.attr,
1844 &dev_attr_max_comp_streams.attr,
1845 &dev_attr_comp_algorithm.attr,
1846 #ifdef CONFIG_ZRAM_WRITEBACK
1847 &dev_attr_backing_dev.attr,
1848 &dev_attr_writeback.attr,
1849 &dev_attr_writeback_limit.attr,
1850 &dev_attr_writeback_limit_enable.attr,
1852 &dev_attr_io_stat.attr,
1853 &dev_attr_mm_stat.attr,
1854 #ifdef CONFIG_ZRAM_WRITEBACK
1855 &dev_attr_bd_stat.attr,
1857 &dev_attr_debug_stat.attr,
1861 static const struct attribute_group zram_disk_attr_group = {
1862 .attrs = zram_disk_attrs,
1865 static const struct attribute_group *zram_disk_attr_groups[] = {
1866 &zram_disk_attr_group,
1871 * Allocate and initialize new zram device. the function returns
1872 * '>= 0' device_id upon success, and negative value otherwise.
1874 static int zram_add(void)
1877 struct request_queue *queue;
1880 zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
1884 ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
1889 init_rwsem(&zram->init_lock);
1890 #ifdef CONFIG_ZRAM_WRITEBACK
1891 spin_lock_init(&zram->wb_limit_lock);
1893 queue = blk_alloc_queue(GFP_KERNEL);
1895 pr_err("Error allocating disk queue for device %d\n",
1901 blk_queue_make_request(queue, zram_make_request);
1903 /* gendisk structure */
1904 zram->disk = alloc_disk(1);
1906 pr_err("Error allocating disk structure for device %d\n",
1909 goto out_free_queue;
1912 zram->disk->major = zram_major;
1913 zram->disk->first_minor = device_id;
1914 zram->disk->fops = &zram_devops;
1915 zram->disk->queue = queue;
1916 zram->disk->queue->queuedata = zram;
1917 zram->disk->private_data = zram;
1918 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1920 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1921 set_capacity(zram->disk, 0);
1922 /* zram devices sort of resembles non-rotational disks */
1923 blk_queue_flag_set(QUEUE_FLAG_NONROT, zram->disk->queue);
1924 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1927 * To ensure that we always get PAGE_SIZE aligned
1928 * and n*PAGE_SIZED sized I/O requests.
1930 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1931 blk_queue_logical_block_size(zram->disk->queue,
1932 ZRAM_LOGICAL_BLOCK_SIZE);
1933 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1934 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1935 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1936 blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
1937 blk_queue_flag_set(QUEUE_FLAG_DISCARD, zram->disk->queue);
1940 * zram_bio_discard() will clear all logical blocks if logical block
1941 * size is identical with physical block size(PAGE_SIZE). But if it is
1942 * different, we will skip discarding some parts of logical blocks in
1943 * the part of the request range which isn't aligned to physical block
1944 * size. So we can't ensure that all discarded logical blocks are
1947 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1948 blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
1950 zram->disk->queue->backing_dev_info->capabilities |=
1951 (BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO);
1952 device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
1954 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1956 zram_debugfs_register(zram);
1957 pr_info("Added device: %s\n", zram->disk->disk_name);
1961 blk_cleanup_queue(queue);
1963 idr_remove(&zram_index_idr, device_id);
1969 static int zram_remove(struct zram *zram)
1971 struct block_device *bdev;
1973 bdev = bdget_disk(zram->disk, 0);
1977 mutex_lock(&bdev->bd_mutex);
1978 if (bdev->bd_openers || zram->claim) {
1979 mutex_unlock(&bdev->bd_mutex);
1985 mutex_unlock(&bdev->bd_mutex);
1987 zram_debugfs_unregister(zram);
1989 /* Make sure all the pending I/O are finished */
1991 zram_reset_device(zram);
1994 pr_info("Removed device: %s\n", zram->disk->disk_name);
1996 del_gendisk(zram->disk);
1997 blk_cleanup_queue(zram->disk->queue);
1998 put_disk(zram->disk);
2003 /* zram-control sysfs attributes */
2006 * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
2007 * sense that reading from this file does alter the state of your system -- it
2008 * creates a new un-initialized zram device and returns back this device's
2009 * device_id (or an error code if it fails to create a new device).
2011 static ssize_t hot_add_show(struct class *class,
2012 struct class_attribute *attr,
2017 mutex_lock(&zram_index_mutex);
2019 mutex_unlock(&zram_index_mutex);
2023 return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
2025 static CLASS_ATTR_RO(hot_add);
2027 static ssize_t hot_remove_store(struct class *class,
2028 struct class_attribute *attr,
2035 /* dev_id is gendisk->first_minor, which is `int' */
2036 ret = kstrtoint(buf, 10, &dev_id);
2042 mutex_lock(&zram_index_mutex);
2044 zram = idr_find(&zram_index_idr, dev_id);
2046 ret = zram_remove(zram);
2048 idr_remove(&zram_index_idr, dev_id);
2053 mutex_unlock(&zram_index_mutex);
2054 return ret ? ret : count;
2056 static CLASS_ATTR_WO(hot_remove);
2058 static struct attribute *zram_control_class_attrs[] = {
2059 &class_attr_hot_add.attr,
2060 &class_attr_hot_remove.attr,
2063 ATTRIBUTE_GROUPS(zram_control_class);
2065 static struct class zram_control_class = {
2066 .name = "zram-control",
2067 .owner = THIS_MODULE,
2068 .class_groups = zram_control_class_groups,
2071 static int zram_remove_cb(int id, void *ptr, void *data)
2077 static void destroy_devices(void)
2079 class_unregister(&zram_control_class);
2080 idr_for_each(&zram_index_idr, &zram_remove_cb, NULL);
2081 zram_debugfs_destroy();
2082 idr_destroy(&zram_index_idr);
2083 unregister_blkdev(zram_major, "zram");
2084 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
2087 static int __init zram_init(void)
2091 ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
2092 zcomp_cpu_up_prepare, zcomp_cpu_dead);
2096 ret = class_register(&zram_control_class);
2098 pr_err("Unable to register zram-control class\n");
2099 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
2103 zram_debugfs_create();
2104 zram_major = register_blkdev(0, "zram");
2105 if (zram_major <= 0) {
2106 pr_err("Unable to get major number\n");
2107 class_unregister(&zram_control_class);
2108 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
2112 while (num_devices != 0) {
2113 mutex_lock(&zram_index_mutex);
2115 mutex_unlock(&zram_index_mutex);
2128 static void __exit zram_exit(void)
2133 module_init(zram_init);
2134 module_exit(zram_exit);
2136 module_param(num_devices, uint, 0);
2137 MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
2139 MODULE_LICENSE("Dual BSD/GPL");
2140 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
2141 MODULE_DESCRIPTION("Compressed RAM Block Device");