/* * Compressed RAM block device * * Copyright (C) 2008, 2009, 2010 Nitin Gupta * 2012, 2013 Minchan Kim * * This code is released using a dual license strategy: BSD/GPL * You can choose the licence that better fits your requirements. * * Released under the terms of 3-clause BSD License * Released under the terms of GNU General Public License Version 2.0 * */ #define KMSG_COMPONENT "zram" #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt #ifdef CONFIG_ZRAM_DEBUG #define DEBUG #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include "zram_drv.h" /* Globals */ static int zram_major; static struct zram *zram_devices; static const char *default_compressor = "lzo"; /* Module params (documentation at end) */ static unsigned int num_devices = 1; #define ZRAM_ATTR_RO(name) \ static ssize_t zram_attr_##name##_show(struct device *d, \ struct device_attribute *attr, char *b) \ { \ struct zram *zram = dev_to_zram(d); \ return scnprintf(b, PAGE_SIZE, "%llu\n", \ (u64)atomic64_read(&zram->stats.name)); \ } \ static struct device_attribute dev_attr_##name = \ __ATTR(name, S_IRUGO, zram_attr_##name##_show, NULL); static inline int init_done(struct zram *zram) { return zram->meta != NULL; } static inline struct zram *dev_to_zram(struct device *dev) { return (struct zram *)dev_to_disk(dev)->private_data; } static ssize_t disksize_show(struct device *dev, struct device_attribute *attr, char *buf) { struct zram *zram = dev_to_zram(dev); return scnprintf(buf, PAGE_SIZE, "%llu\n", zram->disksize); } static ssize_t initstate_show(struct device *dev, struct device_attribute *attr, char *buf) { u32 val; struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); val = init_done(zram); up_read(&zram->init_lock); return scnprintf(buf, PAGE_SIZE, "%u\n", val); } static ssize_t orig_data_size_show(struct device *dev, struct device_attribute *attr, char *buf) { struct zram *zram = dev_to_zram(dev); return scnprintf(buf, PAGE_SIZE, "%llu\n", (u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT); } static ssize_t mem_used_total_show(struct device *dev, struct device_attribute *attr, char *buf) { u64 val = 0; struct zram *zram = dev_to_zram(dev); struct zram_meta *meta = zram->meta; down_read(&zram->init_lock); if (init_done(zram)) val = zs_get_total_pages(meta->mem_pool); up_read(&zram->init_lock); return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT); } static ssize_t max_comp_streams_show(struct device *dev, struct device_attribute *attr, char *buf) { int val; struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); val = zram->max_comp_streams; up_read(&zram->init_lock); return scnprintf(buf, PAGE_SIZE, "%d\n", val); } static ssize_t max_comp_streams_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { int num; struct zram *zram = dev_to_zram(dev); int ret; ret = kstrtoint(buf, 0, &num); if (ret < 0) return ret; if (num < 1) return -EINVAL; down_write(&zram->init_lock); if (init_done(zram)) { if (!zcomp_set_max_streams(zram->comp, num)) { pr_info("Cannot change max compression streams\n"); ret = -EINVAL; goto out; } } zram->max_comp_streams = num; ret = len; out: up_write(&zram->init_lock); return ret; } static ssize_t comp_algorithm_show(struct device *dev, struct device_attribute *attr, char *buf) { size_t sz; struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); sz = zcomp_available_show(zram->compressor, buf); up_read(&zram->init_lock); return sz; } static ssize_t comp_algorithm_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); down_write(&zram->init_lock); if (init_done(zram)) { up_write(&zram->init_lock); pr_info("Can't change algorithm for initialized device\n"); return -EBUSY; } strlcpy(zram->compressor, buf, sizeof(zram->compressor)); up_write(&zram->init_lock); return len; } /* flag operations needs meta->tb_lock */ static int zram_test_flag(struct zram_meta *meta, u32 index, enum zram_pageflags flag) { return meta->table[index].value & BIT(flag); } static void zram_set_flag(struct zram_meta *meta, u32 index, enum zram_pageflags flag) { meta->table[index].value |= BIT(flag); } static void zram_clear_flag(struct zram_meta *meta, u32 index, enum zram_pageflags flag) { meta->table[index].value &= ~BIT(flag); } static size_t zram_get_obj_size(struct zram_meta *meta, u32 index) { return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1); } static void zram_set_obj_size(struct zram_meta *meta, u32 index, size_t size) { unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT; meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size; } static inline int is_partial_io(struct bio_vec *bvec) { return bvec->bv_len != PAGE_SIZE; } /* * Check if request is within bounds and aligned on zram logical blocks. */ static inline int valid_io_request(struct zram *zram, struct bio *bio) { u64 start, end, bound; /* unaligned request */ if (unlikely(bio->bi_iter.bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1))) return 0; if (unlikely(bio->bi_iter.bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1))) return 0; start = bio->bi_iter.bi_sector; end = start + (bio->bi_iter.bi_size >> SECTOR_SHIFT); bound = zram->disksize >> SECTOR_SHIFT; /* out of range range */ if (unlikely(start >= bound || end > bound || start > end)) return 0; /* I/O request is valid */ return 1; } static void zram_meta_free(struct zram_meta *meta) { zs_destroy_pool(meta->mem_pool); vfree(meta->table); kfree(meta); } static struct zram_meta *zram_meta_alloc(u64 disksize) { size_t num_pages; struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL); if (!meta) goto out; num_pages = disksize >> PAGE_SHIFT; meta->table = vzalloc(num_pages * sizeof(*meta->table)); if (!meta->table) { pr_err("Error allocating zram address table\n"); goto free_meta; } meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM); if (!meta->mem_pool) { pr_err("Error creating memory pool\n"); goto free_table; } return meta; free_table: vfree(meta->table); free_meta: kfree(meta); meta = NULL; out: return meta; } static void update_position(u32 *index, int *offset, struct bio_vec *bvec) { if (*offset + bvec->bv_len >= PAGE_SIZE) (*index)++; *offset = (*offset + bvec->bv_len) % PAGE_SIZE; } static int page_zero_filled(void *ptr) { unsigned int pos; unsigned long *page; page = (unsigned long *)ptr; for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) { if (page[pos]) return 0; } return 1; } static void handle_zero_page(struct bio_vec *bvec) { struct page *page = bvec->bv_page; void *user_mem; user_mem = kmap_atomic(page); if (is_partial_io(bvec)) memset(user_mem + bvec->bv_offset, 0, bvec->bv_len); else clear_page(user_mem); kunmap_atomic(user_mem); flush_dcache_page(page); } /* * To protect concurrent access to the same index entry, * caller should hold this table index entry's bit_spinlock to * indicate this index entry is accessing. */ static void zram_free_page(struct zram *zram, size_t index) { struct zram_meta *meta = zram->meta; unsigned long handle = meta->table[index].handle; if (unlikely(!handle)) { /* * No memory is allocated for zero filled pages. * Simply clear zero page flag. */ if (zram_test_flag(meta, index, ZRAM_ZERO)) { zram_clear_flag(meta, index, ZRAM_ZERO); atomic64_dec(&zram->stats.zero_pages); } return; } zs_free(meta->mem_pool, handle); atomic64_sub(zram_get_obj_size(meta, index), &zram->stats.compr_data_size); atomic64_dec(&zram->stats.pages_stored); meta->table[index].handle = 0; zram_set_obj_size(meta, index, 0); } static int zram_decompress_page(struct zram *zram, char *mem, u32 index) { int ret = 0; unsigned char *cmem; struct zram_meta *meta = zram->meta; unsigned long handle; size_t size; bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); handle = meta->table[index].handle; size = zram_get_obj_size(meta, index); if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) { bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); clear_page(mem); return 0; } cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO); if (size == PAGE_SIZE) copy_page(mem, cmem); else ret = zcomp_decompress(zram->comp, cmem, size, mem); zs_unmap_object(meta->mem_pool, handle); bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); /* Should NEVER happen. Return bio error if it does. */ if (unlikely(ret)) { pr_err("Decompression failed! err=%d, page=%u\n", ret, index); return ret; } return 0; } static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, u32 index, int offset, struct bio *bio) { int ret; struct page *page; unsigned char *user_mem, *uncmem = NULL; struct zram_meta *meta = zram->meta; page = bvec->bv_page; bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); if (unlikely(!meta->table[index].handle) || zram_test_flag(meta, index, ZRAM_ZERO)) { bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); handle_zero_page(bvec); return 0; } bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); if (is_partial_io(bvec)) /* Use a temporary buffer to decompress the page */ uncmem = kmalloc(PAGE_SIZE, GFP_NOIO); user_mem = kmap_atomic(page); if (!is_partial_io(bvec)) uncmem = user_mem; if (!uncmem) { pr_info("Unable to allocate temp memory\n"); ret = -ENOMEM; goto out_cleanup; } ret = zram_decompress_page(zram, uncmem, index); /* Should NEVER happen. Return bio error if it does. */ if (unlikely(ret)) goto out_cleanup; if (is_partial_io(bvec)) memcpy(user_mem + bvec->bv_offset, uncmem + offset, bvec->bv_len); flush_dcache_page(page); ret = 0; out_cleanup: kunmap_atomic(user_mem); if (is_partial_io(bvec)) kfree(uncmem); return ret; } static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, int offset) { int ret = 0; size_t clen; unsigned long handle; struct page *page; unsigned char *user_mem, *cmem, *src, *uncmem = NULL; struct zram_meta *meta = zram->meta; struct zcomp_strm *zstrm; bool locked = false; page = bvec->bv_page; if (is_partial_io(bvec)) { /* * This is a partial IO. We need to read the full page * before to write the changes. */ uncmem = kmalloc(PAGE_SIZE, GFP_NOIO); if (!uncmem) { ret = -ENOMEM; goto out; } ret = zram_decompress_page(zram, uncmem, index); if (ret) goto out; } zstrm = zcomp_strm_find(zram->comp); locked = true; user_mem = kmap_atomic(page); if (is_partial_io(bvec)) { memcpy(uncmem + offset, user_mem + bvec->bv_offset, bvec->bv_len); kunmap_atomic(user_mem); user_mem = NULL; } else { uncmem = user_mem; } if (page_zero_filled(uncmem)) { kunmap_atomic(user_mem); /* Free memory associated with this sector now. */ bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); zram_set_flag(meta, index, ZRAM_ZERO); bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); atomic64_inc(&zram->stats.zero_pages); ret = 0; goto out; } ret = zcomp_compress(zram->comp, zstrm, uncmem, &clen); if (!is_partial_io(bvec)) { kunmap_atomic(user_mem); user_mem = NULL; uncmem = NULL; } if (unlikely(ret)) { pr_err("Compression failed! err=%d\n", ret); goto out; } src = zstrm->buffer; if (unlikely(clen > max_zpage_size)) { clen = PAGE_SIZE; if (is_partial_io(bvec)) src = uncmem; } handle = zs_malloc(meta->mem_pool, clen); if (!handle) { pr_info("Error allocating memory for compressed page: %u, size=%zu\n", index, clen); ret = -ENOMEM; goto out; } cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO); if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) { src = kmap_atomic(page); copy_page(cmem, src); kunmap_atomic(src); } else { memcpy(cmem, src, clen); } zcomp_strm_release(zram->comp, zstrm); locked = false; zs_unmap_object(meta->mem_pool, handle); /* * Free memory associated with this sector * before overwriting unused sectors. */ bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); meta->table[index].handle = handle; zram_set_obj_size(meta, index, clen); bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); /* Update stats */ atomic64_add(clen, &zram->stats.compr_data_size); atomic64_inc(&zram->stats.pages_stored); out: if (locked) zcomp_strm_release(zram->comp, zstrm); if (is_partial_io(bvec)) kfree(uncmem); return ret; } static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, int offset, struct bio *bio) { int ret; int rw = bio_data_dir(bio); if (rw == READ) { atomic64_inc(&zram->stats.num_reads); ret = zram_bvec_read(zram, bvec, index, offset, bio); } else { atomic64_inc(&zram->stats.num_writes); ret = zram_bvec_write(zram, bvec, index, offset); } if (unlikely(ret)) { if (rw == READ) atomic64_inc(&zram->stats.failed_reads); else atomic64_inc(&zram->stats.failed_writes); } return ret; } /* * zram_bio_discard - handler on discard request * @index: physical block index in PAGE_SIZE units * @offset: byte offset within physical block */ static void zram_bio_discard(struct zram *zram, u32 index, int offset, struct bio *bio) { size_t n = bio->bi_iter.bi_size; struct zram_meta *meta = zram->meta; /* * zram manages data in physical block size units. Because logical block * size isn't identical with physical block size on some arch, we * could get a discard request pointing to a specific offset within a * certain physical block. Although we can handle this request by * reading that physiclal block and decompressing and partially zeroing * and re-compressing and then re-storing it, this isn't reasonable * because our intent with a discard request is to save memory. So * skipping this logical block is appropriate here. */ if (offset) { if (n <= (PAGE_SIZE - offset)) return; n -= (PAGE_SIZE - offset); index++; } while (n >= PAGE_SIZE) { bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); index++; n -= PAGE_SIZE; } } static void zram_reset_device(struct zram *zram, bool reset_capacity) { size_t index; struct zram_meta *meta; down_write(&zram->init_lock); if (!init_done(zram)) { up_write(&zram->init_lock); return; } meta = zram->meta; /* Free all pages that are still in this zram device */ for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) { unsigned long handle = meta->table[index].handle; if (!handle) continue; zs_free(meta->mem_pool, handle); } zcomp_destroy(zram->comp); zram->max_comp_streams = 1; zram_meta_free(zram->meta); zram->meta = NULL; /* Reset stats */ memset(&zram->stats, 0, sizeof(zram->stats)); zram->disksize = 0; if (reset_capacity) set_capacity(zram->disk, 0); up_write(&zram->init_lock); /* * Revalidate disk out of the init_lock to avoid lockdep splat. * It's okay because disk's capacity is protected by init_lock * so that revalidate_disk always sees up-to-date capacity. */ if (reset_capacity) revalidate_disk(zram->disk); } static ssize_t disksize_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { u64 disksize; struct zcomp *comp; struct zram_meta *meta; struct zram *zram = dev_to_zram(dev); int err; disksize = memparse(buf, NULL); if (!disksize) return -EINVAL; disksize = PAGE_ALIGN(disksize); meta = zram_meta_alloc(disksize); if (!meta) return -ENOMEM; comp = zcomp_create(zram->compressor, zram->max_comp_streams); if (IS_ERR(comp)) { pr_info("Cannot initialise %s compressing backend\n", zram->compressor); err = PTR_ERR(comp); goto out_free_meta; } down_write(&zram->init_lock); if (init_done(zram)) { pr_info("Cannot change disksize for initialized device\n"); err = -EBUSY; goto out_destroy_comp; } zram->meta = meta; zram->comp = comp; zram->disksize = disksize; set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT); up_write(&zram->init_lock); /* * Revalidate disk out of the init_lock to avoid lockdep splat. * It's okay because disk's capacity is protected by init_lock * so that revalidate_disk always sees up-to-date capacity. */ revalidate_disk(zram->disk); return len; out_destroy_comp: up_write(&zram->init_lock); zcomp_destroy(comp); out_free_meta: zram_meta_free(meta); return err; } static ssize_t reset_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { int ret; unsigned short do_reset; struct zram *zram; struct block_device *bdev; zram = dev_to_zram(dev); bdev = bdget_disk(zram->disk, 0); if (!bdev) return -ENOMEM; /* Do not reset an active device! */ if (bdev->bd_holders) { ret = -EBUSY; goto out; } ret = kstrtou16(buf, 10, &do_reset); if (ret) goto out; if (!do_reset) { ret = -EINVAL; goto out; } /* Make sure all pending I/O is finished */ fsync_bdev(bdev); bdput(bdev); zram_reset_device(zram, true); return len; out: bdput(bdev); return ret; } static void __zram_make_request(struct zram *zram, struct bio *bio) { int offset; u32 index; struct bio_vec bvec; struct bvec_iter iter; index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT; offset = (bio->bi_iter.bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT; if (unlikely(bio->bi_rw & REQ_DISCARD)) { zram_bio_discard(zram, index, offset, bio); bio_endio(bio, 0); return; } bio_for_each_segment(bvec, bio, iter) { int max_transfer_size = PAGE_SIZE - offset; if (bvec.bv_len > max_transfer_size) { /* * zram_bvec_rw() can only make operation on a single * zram page. Split the bio vector. */ struct bio_vec bv; bv.bv_page = bvec.bv_page; bv.bv_len = max_transfer_size; bv.bv_offset = bvec.bv_offset; if (zram_bvec_rw(zram, &bv, index, offset, bio) < 0) goto out; bv.bv_len = bvec.bv_len - max_transfer_size; bv.bv_offset += max_transfer_size; if (zram_bvec_rw(zram, &bv, index + 1, 0, bio) < 0) goto out; } else if (zram_bvec_rw(zram, &bvec, index, offset, bio) < 0) goto out; update_position(&index, &offset, &bvec); } set_bit(BIO_UPTODATE, &bio->bi_flags); bio_endio(bio, 0); return; out: bio_io_error(bio); } /* * Handler function for all zram I/O requests. */ static void zram_make_request(struct request_queue *queue, struct bio *bio) { struct zram *zram = queue->queuedata; down_read(&zram->init_lock); if (unlikely(!init_done(zram))) goto error; if (!valid_io_request(zram, bio)) { atomic64_inc(&zram->stats.invalid_io); goto error; } __zram_make_request(zram, bio); up_read(&zram->init_lock); return; error: up_read(&zram->init_lock); bio_io_error(bio); } static void zram_slot_free_notify(struct block_device *bdev, unsigned long index) { struct zram *zram; struct zram_meta *meta; zram = bdev->bd_disk->private_data; meta = zram->meta; bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); atomic64_inc(&zram->stats.notify_free); } static const struct block_device_operations zram_devops = { .swap_slot_free_notify = zram_slot_free_notify, .owner = THIS_MODULE }; static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR, disksize_show, disksize_store); static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL); static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store); static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL); static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL); static DEVICE_ATTR(max_comp_streams, S_IRUGO | S_IWUSR, max_comp_streams_show, max_comp_streams_store); static DEVICE_ATTR(comp_algorithm, S_IRUGO | S_IWUSR, comp_algorithm_show, comp_algorithm_store); ZRAM_ATTR_RO(num_reads); ZRAM_ATTR_RO(num_writes); ZRAM_ATTR_RO(failed_reads); ZRAM_ATTR_RO(failed_writes); ZRAM_ATTR_RO(invalid_io); ZRAM_ATTR_RO(notify_free); ZRAM_ATTR_RO(zero_pages); ZRAM_ATTR_RO(compr_data_size); static struct attribute *zram_disk_attrs[] = { &dev_attr_disksize.attr, &dev_attr_initstate.attr, &dev_attr_reset.attr, &dev_attr_num_reads.attr, &dev_attr_num_writes.attr, &dev_attr_failed_reads.attr, &dev_attr_failed_writes.attr, &dev_attr_invalid_io.attr, &dev_attr_notify_free.attr, &dev_attr_zero_pages.attr, &dev_attr_orig_data_size.attr, &dev_attr_compr_data_size.attr, &dev_attr_mem_used_total.attr, &dev_attr_max_comp_streams.attr, &dev_attr_comp_algorithm.attr, NULL, }; static struct attribute_group zram_disk_attr_group = { .attrs = zram_disk_attrs, }; static int create_device(struct zram *zram, int device_id) { int ret = -ENOMEM; init_rwsem(&zram->init_lock); zram->queue = blk_alloc_queue(GFP_KERNEL); if (!zram->queue) { pr_err("Error allocating disk queue for device %d\n", device_id); goto out; } blk_queue_make_request(zram->queue, zram_make_request); zram->queue->queuedata = zram; /* gendisk structure */ zram->disk = alloc_disk(1); if (!zram->disk) { pr_warn("Error allocating disk structure for device %d\n", device_id); goto out_free_queue; } zram->disk->major = zram_major; zram->disk->first_minor = device_id; zram->disk->fops = &zram_devops; zram->disk->queue = zram->queue; zram->disk->private_data = zram; snprintf(zram->disk->disk_name, 16, "zram%d", device_id); /* Actual capacity set using syfs (/sys/block/zram/disksize */ set_capacity(zram->disk, 0); /* zram devices sort of resembles non-rotational disks */ queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue); /* * To ensure that we always get PAGE_SIZE aligned * and n*PAGE_SIZED sized I/O requests. */ blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE); blk_queue_logical_block_size(zram->disk->queue, ZRAM_LOGICAL_BLOCK_SIZE); blk_queue_io_min(zram->disk->queue, PAGE_SIZE); blk_queue_io_opt(zram->disk->queue, PAGE_SIZE); zram->disk->queue->limits.discard_granularity = PAGE_SIZE; zram->disk->queue->limits.max_discard_sectors = UINT_MAX; /* * zram_bio_discard() will clear all logical blocks if logical block * size is identical with physical block size(PAGE_SIZE). But if it is * different, we will skip discarding some parts of logical blocks in * the part of the request range which isn't aligned to physical block * size. So we can't ensure that all discarded logical blocks are * zeroed. */ if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE) zram->disk->queue->limits.discard_zeroes_data = 1; else zram->disk->queue->limits.discard_zeroes_data = 0; queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue); add_disk(zram->disk); ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj, &zram_disk_attr_group); if (ret < 0) { pr_warn("Error creating sysfs group"); goto out_free_disk; } strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor)); zram->meta = NULL; zram->max_comp_streams = 1; return 0; out_free_disk: del_gendisk(zram->disk); put_disk(zram->disk); out_free_queue: blk_cleanup_queue(zram->queue); out: return ret; } static void destroy_device(struct zram *zram) { sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, &zram_disk_attr_group); del_gendisk(zram->disk); put_disk(zram->disk); blk_cleanup_queue(zram->queue); } static int __init zram_init(void) { int ret, dev_id; if (num_devices > max_num_devices) { pr_warn("Invalid value for num_devices: %u\n", num_devices); ret = -EINVAL; goto out; } zram_major = register_blkdev(0, "zram"); if (zram_major <= 0) { pr_warn("Unable to get major number\n"); ret = -EBUSY; goto out; } /* Allocate the device array and initialize each one */ zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL); if (!zram_devices) { ret = -ENOMEM; goto unregister; } for (dev_id = 0; dev_id < num_devices; dev_id++) { ret = create_device(&zram_devices[dev_id], dev_id); if (ret) goto free_devices; } pr_info("Created %u device(s) ...\n", num_devices); return 0; free_devices: while (dev_id) destroy_device(&zram_devices[--dev_id]); kfree(zram_devices); unregister: unregister_blkdev(zram_major, "zram"); out: return ret; } static void __exit zram_exit(void) { int i; struct zram *zram; for (i = 0; i < num_devices; i++) { zram = &zram_devices[i]; destroy_device(zram); /* * Shouldn't access zram->disk after destroy_device * because destroy_device already released zram->disk. */ zram_reset_device(zram, false); } unregister_blkdev(zram_major, "zram"); kfree(zram_devices); pr_debug("Cleanup done!\n"); } module_init(zram_init); module_exit(zram_exit); module_param(num_devices, uint, 0); MODULE_PARM_DESC(num_devices, "Number of zram devices"); MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Nitin Gupta "); MODULE_DESCRIPTION("Compressed RAM Block Device");