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/cpuhotplug.h>
38 static DEFINE_IDR(zram_index_idr);
39 /* idr index must be protected */
40 static DEFINE_MUTEX(zram_index_mutex);
42 static int zram_major;
43 static const char *default_compressor = "lzo";
45 /* Module params (documentation at end) */
46 static unsigned int num_devices = 1;
48 static void zram_free_page(struct zram *zram, size_t index);
50 static inline bool init_done(struct zram *zram)
52 return zram->disksize;
55 static inline struct zram *dev_to_zram(struct device *dev)
57 return (struct zram *)dev_to_disk(dev)->private_data;
60 static unsigned long zram_get_handle(struct zram *zram, u32 index)
62 return zram->table[index].handle;
65 static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle)
67 zram->table[index].handle = handle;
70 /* flag operations require table entry bit_spin_lock() being held */
71 static int zram_test_flag(struct zram *zram, u32 index,
72 enum zram_pageflags flag)
74 return zram->table[index].value & BIT(flag);
77 static void zram_set_flag(struct zram *zram, u32 index,
78 enum zram_pageflags flag)
80 zram->table[index].value |= BIT(flag);
83 static void zram_clear_flag(struct zram *zram, u32 index,
84 enum zram_pageflags flag)
86 zram->table[index].value &= ~BIT(flag);
89 static inline void zram_set_element(struct zram *zram, u32 index,
90 unsigned long element)
92 zram->table[index].element = element;
95 static unsigned long zram_get_element(struct zram *zram, u32 index)
97 return zram->table[index].element;
100 static size_t zram_get_obj_size(struct zram *zram, u32 index)
102 return zram->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
105 static void zram_set_obj_size(struct zram *zram,
106 u32 index, size_t size)
108 unsigned long flags = zram->table[index].value >> ZRAM_FLAG_SHIFT;
110 zram->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
113 #if PAGE_SIZE != 4096
114 static inline bool is_partial_io(struct bio_vec *bvec)
116 return bvec->bv_len != PAGE_SIZE;
119 static inline bool is_partial_io(struct bio_vec *bvec)
125 static void zram_revalidate_disk(struct zram *zram)
127 revalidate_disk(zram->disk);
128 /* revalidate_disk reset the BDI_CAP_STABLE_WRITES so set again */
129 zram->disk->queue->backing_dev_info->capabilities |=
130 BDI_CAP_STABLE_WRITES;
134 * Check if request is within bounds and aligned on zram logical blocks.
136 static inline bool valid_io_request(struct zram *zram,
137 sector_t start, unsigned int size)
141 /* unaligned request */
142 if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
144 if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
147 end = start + (size >> SECTOR_SHIFT);
148 bound = zram->disksize >> SECTOR_SHIFT;
149 /* out of range range */
150 if (unlikely(start >= bound || end > bound || start > end))
153 /* I/O request is valid */
157 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
159 *index += (*offset + bvec->bv_len) / PAGE_SIZE;
160 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
163 static inline void update_used_max(struct zram *zram,
164 const unsigned long pages)
166 unsigned long old_max, cur_max;
168 old_max = atomic_long_read(&zram->stats.max_used_pages);
173 old_max = atomic_long_cmpxchg(
174 &zram->stats.max_used_pages, cur_max, pages);
175 } while (old_max != cur_max);
178 static inline void zram_fill_page(char *ptr, unsigned long len,
182 unsigned long *page = (unsigned long *)ptr;
184 WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long)));
186 if (likely(value == 0)) {
189 for (i = 0; i < len / sizeof(*page); i++)
194 static bool page_same_filled(void *ptr, unsigned long *element)
200 page = (unsigned long *)ptr;
203 for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
204 if (val != page[pos])
213 static ssize_t initstate_show(struct device *dev,
214 struct device_attribute *attr, char *buf)
217 struct zram *zram = dev_to_zram(dev);
219 down_read(&zram->init_lock);
220 val = init_done(zram);
221 up_read(&zram->init_lock);
223 return scnprintf(buf, PAGE_SIZE, "%u\n", val);
226 static ssize_t disksize_show(struct device *dev,
227 struct device_attribute *attr, char *buf)
229 struct zram *zram = dev_to_zram(dev);
231 return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize);
234 static ssize_t mem_limit_store(struct device *dev,
235 struct device_attribute *attr, const char *buf, size_t len)
239 struct zram *zram = dev_to_zram(dev);
241 limit = memparse(buf, &tmp);
242 if (buf == tmp) /* no chars parsed, invalid input */
245 down_write(&zram->init_lock);
246 zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
247 up_write(&zram->init_lock);
252 static ssize_t mem_used_max_store(struct device *dev,
253 struct device_attribute *attr, const char *buf, size_t len)
257 struct zram *zram = dev_to_zram(dev);
259 err = kstrtoul(buf, 10, &val);
263 down_read(&zram->init_lock);
264 if (init_done(zram)) {
265 atomic_long_set(&zram->stats.max_used_pages,
266 zs_get_total_pages(zram->mem_pool));
268 up_read(&zram->init_lock);
274 * We switched to per-cpu streams and this attr is not needed anymore.
275 * However, we will keep it around for some time, because:
276 * a) we may revert per-cpu streams in the future
277 * b) it's visible to user space and we need to follow our 2 years
278 * retirement rule; but we already have a number of 'soon to be
279 * altered' attrs, so max_comp_streams need to wait for the next
282 static ssize_t max_comp_streams_show(struct device *dev,
283 struct device_attribute *attr, char *buf)
285 return scnprintf(buf, PAGE_SIZE, "%d\n", num_online_cpus());
288 static ssize_t max_comp_streams_store(struct device *dev,
289 struct device_attribute *attr, const char *buf, size_t len)
294 static ssize_t comp_algorithm_show(struct device *dev,
295 struct device_attribute *attr, char *buf)
298 struct zram *zram = dev_to_zram(dev);
300 down_read(&zram->init_lock);
301 sz = zcomp_available_show(zram->compressor, buf);
302 up_read(&zram->init_lock);
307 static ssize_t comp_algorithm_store(struct device *dev,
308 struct device_attribute *attr, const char *buf, size_t len)
310 struct zram *zram = dev_to_zram(dev);
311 char compressor[ARRAY_SIZE(zram->compressor)];
314 strlcpy(compressor, buf, sizeof(compressor));
315 /* ignore trailing newline */
316 sz = strlen(compressor);
317 if (sz > 0 && compressor[sz - 1] == '\n')
318 compressor[sz - 1] = 0x00;
320 if (!zcomp_available_algorithm(compressor))
323 down_write(&zram->init_lock);
324 if (init_done(zram)) {
325 up_write(&zram->init_lock);
326 pr_info("Can't change algorithm for initialized device\n");
330 strcpy(zram->compressor, compressor);
331 up_write(&zram->init_lock);
335 static ssize_t compact_store(struct device *dev,
336 struct device_attribute *attr, const char *buf, size_t len)
338 struct zram *zram = dev_to_zram(dev);
340 down_read(&zram->init_lock);
341 if (!init_done(zram)) {
342 up_read(&zram->init_lock);
346 zs_compact(zram->mem_pool);
347 up_read(&zram->init_lock);
352 static ssize_t io_stat_show(struct device *dev,
353 struct device_attribute *attr, char *buf)
355 struct zram *zram = dev_to_zram(dev);
358 down_read(&zram->init_lock);
359 ret = scnprintf(buf, PAGE_SIZE,
360 "%8llu %8llu %8llu %8llu\n",
361 (u64)atomic64_read(&zram->stats.failed_reads),
362 (u64)atomic64_read(&zram->stats.failed_writes),
363 (u64)atomic64_read(&zram->stats.invalid_io),
364 (u64)atomic64_read(&zram->stats.notify_free));
365 up_read(&zram->init_lock);
370 static ssize_t mm_stat_show(struct device *dev,
371 struct device_attribute *attr, char *buf)
373 struct zram *zram = dev_to_zram(dev);
374 struct zs_pool_stats pool_stats;
375 u64 orig_size, mem_used = 0;
379 memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats));
381 down_read(&zram->init_lock);
382 if (init_done(zram)) {
383 mem_used = zs_get_total_pages(zram->mem_pool);
384 zs_pool_stats(zram->mem_pool, &pool_stats);
387 orig_size = atomic64_read(&zram->stats.pages_stored);
388 max_used = atomic_long_read(&zram->stats.max_used_pages);
390 ret = scnprintf(buf, PAGE_SIZE,
391 "%8llu %8llu %8llu %8lu %8ld %8llu %8lu\n",
392 orig_size << PAGE_SHIFT,
393 (u64)atomic64_read(&zram->stats.compr_data_size),
394 mem_used << PAGE_SHIFT,
395 zram->limit_pages << PAGE_SHIFT,
396 max_used << PAGE_SHIFT,
397 (u64)atomic64_read(&zram->stats.same_pages),
398 pool_stats.pages_compacted);
399 up_read(&zram->init_lock);
404 static ssize_t debug_stat_show(struct device *dev,
405 struct device_attribute *attr, char *buf)
408 struct zram *zram = dev_to_zram(dev);
411 down_read(&zram->init_lock);
412 ret = scnprintf(buf, PAGE_SIZE,
413 "version: %d\n%8llu\n",
415 (u64)atomic64_read(&zram->stats.writestall));
416 up_read(&zram->init_lock);
421 static DEVICE_ATTR_RO(io_stat);
422 static DEVICE_ATTR_RO(mm_stat);
423 static DEVICE_ATTR_RO(debug_stat);
425 static void zram_slot_lock(struct zram *zram, u32 index)
427 bit_spin_lock(ZRAM_ACCESS, &zram->table[index].value);
430 static void zram_slot_unlock(struct zram *zram, u32 index)
432 bit_spin_unlock(ZRAM_ACCESS, &zram->table[index].value);
435 static bool zram_same_page_read(struct zram *zram, u32 index,
437 unsigned int offset, unsigned int len)
439 zram_slot_lock(zram, index);
440 if (unlikely(!zram_get_handle(zram, index) ||
441 zram_test_flag(zram, index, ZRAM_SAME))) {
444 zram_slot_unlock(zram, index);
445 mem = kmap_atomic(page);
446 zram_fill_page(mem + offset, len,
447 zram_get_element(zram, index));
451 zram_slot_unlock(zram, index);
456 static bool zram_same_page_write(struct zram *zram, u32 index,
459 unsigned long element;
460 void *mem = kmap_atomic(page);
462 if (page_same_filled(mem, &element)) {
464 /* Free memory associated with this sector now. */
465 zram_slot_lock(zram, index);
466 zram_free_page(zram, index);
467 zram_set_flag(zram, index, ZRAM_SAME);
468 zram_set_element(zram, index, element);
469 zram_slot_unlock(zram, index);
471 atomic64_inc(&zram->stats.same_pages);
472 atomic64_inc(&zram->stats.pages_stored);
480 static void zram_meta_free(struct zram *zram, u64 disksize)
482 size_t num_pages = disksize >> PAGE_SHIFT;
485 /* Free all pages that are still in this zram device */
486 for (index = 0; index < num_pages; index++)
487 zram_free_page(zram, index);
489 zs_destroy_pool(zram->mem_pool);
493 static bool zram_meta_alloc(struct zram *zram, u64 disksize)
497 num_pages = disksize >> PAGE_SHIFT;
498 zram->table = vzalloc(num_pages * sizeof(*zram->table));
502 zram->mem_pool = zs_create_pool(zram->disk->disk_name);
503 if (!zram->mem_pool) {
512 * To protect concurrent access to the same index entry,
513 * caller should hold this table index entry's bit_spinlock to
514 * indicate this index entry is accessing.
516 static void zram_free_page(struct zram *zram, size_t index)
518 unsigned long handle = zram_get_handle(zram, index);
521 * No memory is allocated for same element filled pages.
522 * Simply clear same page flag.
524 if (zram_test_flag(zram, index, ZRAM_SAME)) {
525 zram_clear_flag(zram, index, ZRAM_SAME);
526 zram_set_element(zram, index, 0);
527 atomic64_dec(&zram->stats.same_pages);
528 atomic64_dec(&zram->stats.pages_stored);
535 zs_free(zram->mem_pool, handle);
537 atomic64_sub(zram_get_obj_size(zram, index),
538 &zram->stats.compr_data_size);
539 atomic64_dec(&zram->stats.pages_stored);
541 zram_set_handle(zram, index, 0);
542 zram_set_obj_size(zram, index, 0);
545 static int zram_decompress_page(struct zram *zram, struct page *page, u32 index)
548 unsigned long handle;
552 if (zram_same_page_read(zram, index, page, 0, PAGE_SIZE))
555 zram_slot_lock(zram, index);
556 handle = zram_get_handle(zram, index);
557 size = zram_get_obj_size(zram, index);
559 src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
560 if (size == PAGE_SIZE) {
561 dst = kmap_atomic(page);
562 memcpy(dst, src, PAGE_SIZE);
566 struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp);
568 dst = kmap_atomic(page);
569 ret = zcomp_decompress(zstrm, src, size, dst);
571 zcomp_stream_put(zram->comp);
573 zs_unmap_object(zram->mem_pool, handle);
574 zram_slot_unlock(zram, index);
576 /* Should NEVER happen. Return bio error if it does. */
578 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
583 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
584 u32 index, int offset)
589 page = bvec->bv_page;
590 if (is_partial_io(bvec)) {
591 /* Use a temporary buffer to decompress the page */
592 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
597 ret = zram_decompress_page(zram, page, index);
601 if (is_partial_io(bvec)) {
602 void *dst = kmap_atomic(bvec->bv_page);
603 void *src = kmap_atomic(page);
605 memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len);
610 if (is_partial_io(bvec))
616 static int zram_compress(struct zram *zram, struct zcomp_strm **zstrm,
618 unsigned long *out_handle, unsigned int *out_comp_len)
621 unsigned int comp_len;
623 unsigned long alloced_pages;
624 unsigned long handle = 0;
627 src = kmap_atomic(page);
628 ret = zcomp_compress(*zstrm, src, &comp_len);
632 pr_err("Compression failed! err=%d\n", ret);
634 zs_free(zram->mem_pool, handle);
638 if (unlikely(comp_len > max_zpage_size))
639 comp_len = PAGE_SIZE;
642 * handle allocation has 2 paths:
643 * a) fast path is executed with preemption disabled (for
644 * per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear,
645 * since we can't sleep;
646 * b) slow path enables preemption and attempts to allocate
647 * the page with __GFP_DIRECT_RECLAIM bit set. we have to
648 * put per-cpu compression stream and, thus, to re-do
649 * the compression once handle is allocated.
651 * if we have a 'non-null' handle here then we are coming
652 * from the slow path and handle has already been allocated.
655 handle = zs_malloc(zram->mem_pool, comp_len,
656 __GFP_KSWAPD_RECLAIM |
661 zcomp_stream_put(zram->comp);
662 atomic64_inc(&zram->stats.writestall);
663 handle = zs_malloc(zram->mem_pool, comp_len,
664 GFP_NOIO | __GFP_HIGHMEM |
666 *zstrm = zcomp_stream_get(zram->comp);
672 alloced_pages = zs_get_total_pages(zram->mem_pool);
673 update_used_max(zram, alloced_pages);
675 if (zram->limit_pages && alloced_pages > zram->limit_pages) {
676 zs_free(zram->mem_pool, handle);
680 *out_handle = handle;
681 *out_comp_len = comp_len;
685 static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index)
688 unsigned long handle;
689 unsigned int comp_len;
691 struct zcomp_strm *zstrm;
692 struct page *page = bvec->bv_page;
694 if (zram_same_page_write(zram, index, page))
697 zstrm = zcomp_stream_get(zram->comp);
698 ret = zram_compress(zram, &zstrm, page, &handle, &comp_len);
700 zcomp_stream_put(zram->comp);
704 dst = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
707 if (comp_len == PAGE_SIZE)
708 src = kmap_atomic(page);
709 memcpy(dst, src, comp_len);
710 if (comp_len == PAGE_SIZE)
713 zcomp_stream_put(zram->comp);
714 zs_unmap_object(zram->mem_pool, handle);
717 * Free memory associated with this sector
718 * before overwriting unused sectors.
720 zram_slot_lock(zram, index);
721 zram_free_page(zram, index);
722 zram_set_handle(zram, index, handle);
723 zram_set_obj_size(zram, index, comp_len);
724 zram_slot_unlock(zram, index);
727 atomic64_add(comp_len, &zram->stats.compr_data_size);
728 atomic64_inc(&zram->stats.pages_stored);
732 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
733 u32 index, int offset)
736 struct page *page = NULL;
741 if (is_partial_io(bvec)) {
744 * This is a partial IO. We need to read the full page
745 * before to write the changes.
747 page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
751 ret = zram_decompress_page(zram, page, index);
755 src = kmap_atomic(bvec->bv_page);
756 dst = kmap_atomic(page);
757 memcpy(dst + offset, src + bvec->bv_offset, bvec->bv_len);
762 vec.bv_len = PAGE_SIZE;
766 ret = __zram_bvec_write(zram, &vec, index);
768 if (is_partial_io(bvec))
774 * zram_bio_discard - handler on discard request
775 * @index: physical block index in PAGE_SIZE units
776 * @offset: byte offset within physical block
778 static void zram_bio_discard(struct zram *zram, u32 index,
779 int offset, struct bio *bio)
781 size_t n = bio->bi_iter.bi_size;
784 * zram manages data in physical block size units. Because logical block
785 * size isn't identical with physical block size on some arch, we
786 * could get a discard request pointing to a specific offset within a
787 * certain physical block. Although we can handle this request by
788 * reading that physiclal block and decompressing and partially zeroing
789 * and re-compressing and then re-storing it, this isn't reasonable
790 * because our intent with a discard request is to save memory. So
791 * skipping this logical block is appropriate here.
794 if (n <= (PAGE_SIZE - offset))
797 n -= (PAGE_SIZE - offset);
801 while (n >= PAGE_SIZE) {
802 zram_slot_lock(zram, index);
803 zram_free_page(zram, index);
804 zram_slot_unlock(zram, index);
805 atomic64_inc(&zram->stats.notify_free);
811 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
812 int offset, bool is_write)
814 unsigned long start_time = jiffies;
815 int rw_acct = is_write ? REQ_OP_WRITE : REQ_OP_READ;
818 generic_start_io_acct(rw_acct, bvec->bv_len >> SECTOR_SHIFT,
822 atomic64_inc(&zram->stats.num_reads);
823 ret = zram_bvec_read(zram, bvec, index, offset);
824 flush_dcache_page(bvec->bv_page);
826 atomic64_inc(&zram->stats.num_writes);
827 ret = zram_bvec_write(zram, bvec, index, offset);
830 generic_end_io_acct(rw_acct, &zram->disk->part0, start_time);
834 atomic64_inc(&zram->stats.failed_reads);
836 atomic64_inc(&zram->stats.failed_writes);
842 static void __zram_make_request(struct zram *zram, struct bio *bio)
847 struct bvec_iter iter;
849 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
850 offset = (bio->bi_iter.bi_sector &
851 (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
853 switch (bio_op(bio)) {
855 case REQ_OP_WRITE_ZEROES:
856 zram_bio_discard(zram, index, offset, bio);
863 bio_for_each_segment(bvec, bio, iter) {
864 struct bio_vec bv = bvec;
865 unsigned int unwritten = bvec.bv_len;
868 bv.bv_len = min_t(unsigned int, PAGE_SIZE - offset,
870 if (zram_bvec_rw(zram, &bv, index, offset,
871 op_is_write(bio_op(bio))) < 0)
874 bv.bv_offset += bv.bv_len;
875 unwritten -= bv.bv_len;
877 update_position(&index, &offset, &bv);
889 * Handler function for all zram I/O requests.
891 static blk_qc_t zram_make_request(struct request_queue *queue, struct bio *bio)
893 struct zram *zram = queue->queuedata;
895 if (!valid_io_request(zram, bio->bi_iter.bi_sector,
896 bio->bi_iter.bi_size)) {
897 atomic64_inc(&zram->stats.invalid_io);
901 __zram_make_request(zram, bio);
902 return BLK_QC_T_NONE;
906 return BLK_QC_T_NONE;
909 static void zram_slot_free_notify(struct block_device *bdev,
914 zram = bdev->bd_disk->private_data;
916 zram_slot_lock(zram, index);
917 zram_free_page(zram, index);
918 zram_slot_unlock(zram, index);
919 atomic64_inc(&zram->stats.notify_free);
922 static int zram_rw_page(struct block_device *bdev, sector_t sector,
923 struct page *page, bool is_write)
925 int offset, err = -EIO;
930 zram = bdev->bd_disk->private_data;
932 if (!valid_io_request(zram, sector, PAGE_SIZE)) {
933 atomic64_inc(&zram->stats.invalid_io);
938 index = sector >> SECTORS_PER_PAGE_SHIFT;
939 offset = (sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
942 bv.bv_len = PAGE_SIZE;
945 err = zram_bvec_rw(zram, &bv, index, offset, is_write);
948 * If I/O fails, just return error(ie, non-zero) without
949 * calling page_endio.
950 * It causes resubmit the I/O with bio request by upper functions
951 * of rw_page(e.g., swap_readpage, __swap_writepage) and
952 * bio->bi_end_io does things to handle the error
953 * (e.g., SetPageError, set_page_dirty and extra works).
956 page_endio(page, is_write, 0);
960 static void zram_reset_device(struct zram *zram)
965 down_write(&zram->init_lock);
967 zram->limit_pages = 0;
969 if (!init_done(zram)) {
970 up_write(&zram->init_lock);
975 disksize = zram->disksize;
978 set_capacity(zram->disk, 0);
979 part_stat_set_all(&zram->disk->part0, 0);
981 up_write(&zram->init_lock);
982 /* I/O operation under all of CPU are done so let's free */
983 zram_meta_free(zram, disksize);
984 memset(&zram->stats, 0, sizeof(zram->stats));
988 static ssize_t disksize_store(struct device *dev,
989 struct device_attribute *attr, const char *buf, size_t len)
993 struct zram *zram = dev_to_zram(dev);
996 disksize = memparse(buf, NULL);
1000 down_write(&zram->init_lock);
1001 if (init_done(zram)) {
1002 pr_info("Cannot change disksize for initialized device\n");
1007 disksize = PAGE_ALIGN(disksize);
1008 if (!zram_meta_alloc(zram, disksize)) {
1013 comp = zcomp_create(zram->compressor);
1015 pr_err("Cannot initialise %s compressing backend\n",
1017 err = PTR_ERR(comp);
1022 zram->disksize = disksize;
1023 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
1024 zram_revalidate_disk(zram);
1025 up_write(&zram->init_lock);
1030 zram_meta_free(zram, disksize);
1032 up_write(&zram->init_lock);
1036 static ssize_t reset_store(struct device *dev,
1037 struct device_attribute *attr, const char *buf, size_t len)
1040 unsigned short do_reset;
1042 struct block_device *bdev;
1044 ret = kstrtou16(buf, 10, &do_reset);
1051 zram = dev_to_zram(dev);
1052 bdev = bdget_disk(zram->disk, 0);
1056 mutex_lock(&bdev->bd_mutex);
1057 /* Do not reset an active device or claimed device */
1058 if (bdev->bd_openers || zram->claim) {
1059 mutex_unlock(&bdev->bd_mutex);
1064 /* From now on, anyone can't open /dev/zram[0-9] */
1066 mutex_unlock(&bdev->bd_mutex);
1068 /* Make sure all the pending I/O are finished */
1070 zram_reset_device(zram);
1071 zram_revalidate_disk(zram);
1074 mutex_lock(&bdev->bd_mutex);
1075 zram->claim = false;
1076 mutex_unlock(&bdev->bd_mutex);
1081 static int zram_open(struct block_device *bdev, fmode_t mode)
1086 WARN_ON(!mutex_is_locked(&bdev->bd_mutex));
1088 zram = bdev->bd_disk->private_data;
1089 /* zram was claimed to reset so open request fails */
1096 static const struct block_device_operations zram_devops = {
1098 .swap_slot_free_notify = zram_slot_free_notify,
1099 .rw_page = zram_rw_page,
1100 .owner = THIS_MODULE
1103 static DEVICE_ATTR_WO(compact);
1104 static DEVICE_ATTR_RW(disksize);
1105 static DEVICE_ATTR_RO(initstate);
1106 static DEVICE_ATTR_WO(reset);
1107 static DEVICE_ATTR_WO(mem_limit);
1108 static DEVICE_ATTR_WO(mem_used_max);
1109 static DEVICE_ATTR_RW(max_comp_streams);
1110 static DEVICE_ATTR_RW(comp_algorithm);
1112 static struct attribute *zram_disk_attrs[] = {
1113 &dev_attr_disksize.attr,
1114 &dev_attr_initstate.attr,
1115 &dev_attr_reset.attr,
1116 &dev_attr_compact.attr,
1117 &dev_attr_mem_limit.attr,
1118 &dev_attr_mem_used_max.attr,
1119 &dev_attr_max_comp_streams.attr,
1120 &dev_attr_comp_algorithm.attr,
1121 &dev_attr_io_stat.attr,
1122 &dev_attr_mm_stat.attr,
1123 &dev_attr_debug_stat.attr,
1127 static const struct attribute_group zram_disk_attr_group = {
1128 .attrs = zram_disk_attrs,
1132 * Allocate and initialize new zram device. the function returns
1133 * '>= 0' device_id upon success, and negative value otherwise.
1135 static int zram_add(void)
1138 struct request_queue *queue;
1141 zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
1145 ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
1150 init_rwsem(&zram->init_lock);
1152 queue = blk_alloc_queue(GFP_KERNEL);
1154 pr_err("Error allocating disk queue for device %d\n",
1160 blk_queue_make_request(queue, zram_make_request);
1162 /* gendisk structure */
1163 zram->disk = alloc_disk(1);
1165 pr_err("Error allocating disk structure for device %d\n",
1168 goto out_free_queue;
1171 zram->disk->major = zram_major;
1172 zram->disk->first_minor = device_id;
1173 zram->disk->fops = &zram_devops;
1174 zram->disk->queue = queue;
1175 zram->disk->queue->queuedata = zram;
1176 zram->disk->private_data = zram;
1177 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
1179 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
1180 set_capacity(zram->disk, 0);
1181 /* zram devices sort of resembles non-rotational disks */
1182 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
1183 queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zram->disk->queue);
1185 * To ensure that we always get PAGE_SIZE aligned
1186 * and n*PAGE_SIZED sized I/O requests.
1188 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
1189 blk_queue_logical_block_size(zram->disk->queue,
1190 ZRAM_LOGICAL_BLOCK_SIZE);
1191 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
1192 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
1193 zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
1194 blk_queue_max_discard_sectors(zram->disk->queue, UINT_MAX);
1195 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
1198 * zram_bio_discard() will clear all logical blocks if logical block
1199 * size is identical with physical block size(PAGE_SIZE). But if it is
1200 * different, we will skip discarding some parts of logical blocks in
1201 * the part of the request range which isn't aligned to physical block
1202 * size. So we can't ensure that all discarded logical blocks are
1205 if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
1206 blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
1208 add_disk(zram->disk);
1210 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
1211 &zram_disk_attr_group);
1213 pr_err("Error creating sysfs group for device %d\n",
1217 strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
1219 pr_info("Added device: %s\n", zram->disk->disk_name);
1223 del_gendisk(zram->disk);
1224 put_disk(zram->disk);
1226 blk_cleanup_queue(queue);
1228 idr_remove(&zram_index_idr, device_id);
1234 static int zram_remove(struct zram *zram)
1236 struct block_device *bdev;
1238 bdev = bdget_disk(zram->disk, 0);
1242 mutex_lock(&bdev->bd_mutex);
1243 if (bdev->bd_openers || zram->claim) {
1244 mutex_unlock(&bdev->bd_mutex);
1250 mutex_unlock(&bdev->bd_mutex);
1253 * Remove sysfs first, so no one will perform a disksize
1254 * store while we destroy the devices. This also helps during
1255 * hot_remove -- zram_reset_device() is the last holder of
1256 * ->init_lock, no later/concurrent disksize_store() or any
1257 * other sysfs handlers are possible.
1259 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
1260 &zram_disk_attr_group);
1262 /* Make sure all the pending I/O are finished */
1264 zram_reset_device(zram);
1267 pr_info("Removed device: %s\n", zram->disk->disk_name);
1269 blk_cleanup_queue(zram->disk->queue);
1270 del_gendisk(zram->disk);
1271 put_disk(zram->disk);
1276 /* zram-control sysfs attributes */
1279 * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
1280 * sense that reading from this file does alter the state of your system -- it
1281 * creates a new un-initialized zram device and returns back this device's
1282 * device_id (or an error code if it fails to create a new device).
1284 static ssize_t hot_add_show(struct class *class,
1285 struct class_attribute *attr,
1290 mutex_lock(&zram_index_mutex);
1292 mutex_unlock(&zram_index_mutex);
1296 return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
1298 static CLASS_ATTR_RO(hot_add);
1300 static ssize_t hot_remove_store(struct class *class,
1301 struct class_attribute *attr,
1308 /* dev_id is gendisk->first_minor, which is `int' */
1309 ret = kstrtoint(buf, 10, &dev_id);
1315 mutex_lock(&zram_index_mutex);
1317 zram = idr_find(&zram_index_idr, dev_id);
1319 ret = zram_remove(zram);
1321 idr_remove(&zram_index_idr, dev_id);
1326 mutex_unlock(&zram_index_mutex);
1327 return ret ? ret : count;
1329 static CLASS_ATTR_WO(hot_remove);
1331 static struct attribute *zram_control_class_attrs[] = {
1332 &class_attr_hot_add.attr,
1333 &class_attr_hot_remove.attr,
1336 ATTRIBUTE_GROUPS(zram_control_class);
1338 static struct class zram_control_class = {
1339 .name = "zram-control",
1340 .owner = THIS_MODULE,
1341 .class_groups = zram_control_class_groups,
1344 static int zram_remove_cb(int id, void *ptr, void *data)
1350 static void destroy_devices(void)
1352 class_unregister(&zram_control_class);
1353 idr_for_each(&zram_index_idr, &zram_remove_cb, NULL);
1354 idr_destroy(&zram_index_idr);
1355 unregister_blkdev(zram_major, "zram");
1356 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
1359 static int __init zram_init(void)
1363 ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare",
1364 zcomp_cpu_up_prepare, zcomp_cpu_dead);
1368 ret = class_register(&zram_control_class);
1370 pr_err("Unable to register zram-control class\n");
1371 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
1375 zram_major = register_blkdev(0, "zram");
1376 if (zram_major <= 0) {
1377 pr_err("Unable to get major number\n");
1378 class_unregister(&zram_control_class);
1379 cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE);
1383 while (num_devices != 0) {
1384 mutex_lock(&zram_index_mutex);
1386 mutex_unlock(&zram_index_mutex);
1399 static void __exit zram_exit(void)
1404 module_init(zram_init);
1405 module_exit(zram_exit);
1407 module_param(num_devices, uint, 0);
1408 MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
1410 MODULE_LICENSE("Dual BSD/GPL");
1411 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
1412 MODULE_DESCRIPTION("Compressed RAM Block Device");