| /* |
| * Compressed RAM block device |
| * |
| * Copyright (C) 2008, 2009, 2010 Nitin Gupta |
| * |
| * 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 |
| * |
| * Project home: http://compcache.googlecode.com |
| */ |
| |
| #define KMSG_COMPONENT "zram" |
| #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/bio.h> |
| #include <linux/bitops.h> |
| #include <linux/blkdev.h> |
| #include <linux/buffer_head.h> |
| #include <linux/device.h> |
| #include <linux/genhd.h> |
| #include <linux/highmem.h> |
| #include <linux/slab.h> |
| #include <linux/lzo.h> |
| #include <linux/string.h> |
| #include <linux/vmalloc.h> |
| |
| #include "zram_drv.h" |
| |
| /* Globals */ |
| static int zram_major; |
| struct zram *devices; |
| |
| /* Module params (documentation at end) */ |
| unsigned int num_devices; |
| |
| static void zram_stat_inc(u32 *v) |
| { |
| *v = *v + 1; |
| } |
| |
| static void zram_stat_dec(u32 *v) |
| { |
| *v = *v - 1; |
| } |
| |
| static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc) |
| { |
| spin_lock(&zram->stat64_lock); |
| *v = *v + inc; |
| spin_unlock(&zram->stat64_lock); |
| } |
| |
| static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec) |
| { |
| spin_lock(&zram->stat64_lock); |
| *v = *v - dec; |
| spin_unlock(&zram->stat64_lock); |
| } |
| |
| static void zram_stat64_inc(struct zram *zram, u64 *v) |
| { |
| zram_stat64_add(zram, v, 1); |
| } |
| |
| static int zram_test_flag(struct zram *zram, u32 index, |
| enum zram_pageflags flag) |
| { |
| return zram->table[index].flags & BIT(flag); |
| } |
| |
| static void zram_set_flag(struct zram *zram, u32 index, |
| enum zram_pageflags flag) |
| { |
| zram->table[index].flags |= BIT(flag); |
| } |
| |
| static void zram_clear_flag(struct zram *zram, u32 index, |
| enum zram_pageflags flag) |
| { |
| zram->table[index].flags &= ~BIT(flag); |
| } |
| |
| 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 zram_set_disksize(struct zram *zram, size_t totalram_bytes) |
| { |
| if (!zram->disksize) { |
| pr_info( |
| "disk size not provided. You can use disksize_kb module " |
| "param to specify size.\nUsing default: (%u%% of RAM).\n", |
| default_disksize_perc_ram |
| ); |
| zram->disksize = default_disksize_perc_ram * |
| (totalram_bytes / 100); |
| } |
| |
| if (zram->disksize > 2 * (totalram_bytes)) { |
| pr_info( |
| "There is little point creating a zram of greater than " |
| "twice the size of memory since we expect a 2:1 compression " |
| "ratio. Note that zram uses about 0.1%% of the size of " |
| "the disk when not in use so a huge zram is " |
| "wasteful.\n" |
| "\tMemory Size: %zu kB\n" |
| "\tSize you selected: %llu kB\n" |
| "Continuing anyway ...\n", |
| totalram_bytes >> 10, zram->disksize |
| ); |
| } |
| |
| zram->disksize &= PAGE_MASK; |
| } |
| |
| static void zram_free_page(struct zram *zram, size_t index) |
| { |
| u32 clen; |
| void *obj; |
| |
| struct page *page = zram->table[index].page; |
| u32 offset = zram->table[index].offset; |
| |
| if (unlikely(!page)) { |
| /* |
| * No memory is allocated for zero filled pages. |
| * Simply clear zero page flag. |
| */ |
| if (zram_test_flag(zram, index, ZRAM_ZERO)) { |
| zram_clear_flag(zram, index, ZRAM_ZERO); |
| zram_stat_dec(&zram->stats.pages_zero); |
| } |
| return; |
| } |
| |
| if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) { |
| clen = PAGE_SIZE; |
| __free_page(page); |
| zram_clear_flag(zram, index, ZRAM_UNCOMPRESSED); |
| zram_stat_dec(&zram->stats.pages_expand); |
| goto out; |
| } |
| |
| obj = kmap_atomic(page, KM_USER0) + offset; |
| clen = xv_get_object_size(obj) - sizeof(struct zobj_header); |
| kunmap_atomic(obj, KM_USER0); |
| |
| xv_free(zram->mem_pool, page, offset); |
| if (clen <= PAGE_SIZE / 2) |
| zram_stat_dec(&zram->stats.good_compress); |
| |
| out: |
| zram_stat64_sub(zram, &zram->stats.compr_size, clen); |
| zram_stat_dec(&zram->stats.pages_stored); |
| |
| zram->table[index].page = NULL; |
| zram->table[index].offset = 0; |
| } |
| |
| static void handle_zero_page(struct page *page) |
| { |
| void *user_mem; |
| |
| user_mem = kmap_atomic(page, KM_USER0); |
| memset(user_mem, 0, PAGE_SIZE); |
| kunmap_atomic(user_mem, KM_USER0); |
| |
| flush_dcache_page(page); |
| } |
| |
| static void handle_uncompressed_page(struct zram *zram, |
| struct page *page, u32 index) |
| { |
| unsigned char *user_mem, *cmem; |
| |
| user_mem = kmap_atomic(page, KM_USER0); |
| cmem = kmap_atomic(zram->table[index].page, KM_USER1) + |
| zram->table[index].offset; |
| |
| memcpy(user_mem, cmem, PAGE_SIZE); |
| kunmap_atomic(user_mem, KM_USER0); |
| kunmap_atomic(cmem, KM_USER1); |
| |
| flush_dcache_page(page); |
| } |
| |
| static int zram_read(struct zram *zram, struct bio *bio) |
| { |
| |
| int i; |
| u32 index; |
| struct bio_vec *bvec; |
| |
| if (unlikely(!zram->init_done)) { |
| set_bit(BIO_UPTODATE, &bio->bi_flags); |
| bio_endio(bio, 0); |
| return 0; |
| } |
| |
| zram_stat64_inc(zram, &zram->stats.num_reads); |
| index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; |
| |
| bio_for_each_segment(bvec, bio, i) { |
| int ret; |
| size_t clen; |
| struct page *page; |
| struct zobj_header *zheader; |
| unsigned char *user_mem, *cmem; |
| |
| page = bvec->bv_page; |
| |
| if (zram_test_flag(zram, index, ZRAM_ZERO)) { |
| handle_zero_page(page); |
| continue; |
| } |
| |
| /* Requested page is not present in compressed area */ |
| if (unlikely(!zram->table[index].page)) { |
| pr_debug("Read before write: sector=%lu, size=%u", |
| (ulong)(bio->bi_sector), bio->bi_size); |
| /* Do nothing */ |
| continue; |
| } |
| |
| /* Page is stored uncompressed since it's incompressible */ |
| if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) { |
| handle_uncompressed_page(zram, page, index); |
| continue; |
| } |
| |
| user_mem = kmap_atomic(page, KM_USER0); |
| clen = PAGE_SIZE; |
| |
| cmem = kmap_atomic(zram->table[index].page, KM_USER1) + |
| zram->table[index].offset; |
| |
| ret = lzo1x_decompress_safe( |
| cmem + sizeof(*zheader), |
| xv_get_object_size(cmem) - sizeof(*zheader), |
| user_mem, &clen); |
| |
| kunmap_atomic(user_mem, KM_USER0); |
| kunmap_atomic(cmem, KM_USER1); |
| |
| /* Should NEVER happen. Return bio error if it does. */ |
| if (unlikely(ret != LZO_E_OK)) { |
| pr_err("Decompression failed! err=%d, page=%u\n", |
| ret, index); |
| zram_stat64_inc(zram, &zram->stats.failed_reads); |
| goto out; |
| } |
| |
| flush_dcache_page(page); |
| index++; |
| } |
| |
| set_bit(BIO_UPTODATE, &bio->bi_flags); |
| bio_endio(bio, 0); |
| return 0; |
| |
| out: |
| bio_io_error(bio); |
| return 0; |
| } |
| |
| static int zram_write(struct zram *zram, struct bio *bio) |
| { |
| int i, ret; |
| u32 index; |
| struct bio_vec *bvec; |
| |
| if (unlikely(!zram->init_done)) { |
| ret = zram_init_device(zram); |
| if (ret) |
| goto out; |
| } |
| |
| zram_stat64_inc(zram, &zram->stats.num_writes); |
| index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; |
| |
| bio_for_each_segment(bvec, bio, i) { |
| u32 offset; |
| size_t clen; |
| struct zobj_header *zheader; |
| struct page *page, *page_store; |
| unsigned char *user_mem, *cmem, *src; |
| |
| page = bvec->bv_page; |
| src = zram->compress_buffer; |
| |
| /* |
| * System overwrites unused sectors. Free memory associated |
| * with this sector now. |
| */ |
| if (zram->table[index].page || |
| zram_test_flag(zram, index, ZRAM_ZERO)) |
| zram_free_page(zram, index); |
| |
| mutex_lock(&zram->lock); |
| |
| user_mem = kmap_atomic(page, KM_USER0); |
| if (page_zero_filled(user_mem)) { |
| kunmap_atomic(user_mem, KM_USER0); |
| mutex_unlock(&zram->lock); |
| zram_stat_inc(&zram->stats.pages_zero); |
| zram_set_flag(zram, index, ZRAM_ZERO); |
| continue; |
| } |
| |
| ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen, |
| zram->compress_workmem); |
| |
| kunmap_atomic(user_mem, KM_USER0); |
| |
| if (unlikely(ret != LZO_E_OK)) { |
| mutex_unlock(&zram->lock); |
| pr_err("Compression failed! err=%d\n", ret); |
| zram_stat64_inc(zram, &zram->stats.failed_writes); |
| goto out; |
| } |
| |
| /* |
| * Page is incompressible. Store it as-is (uncompressed) |
| * since we do not want to return too many disk write |
| * errors which has side effect of hanging the system. |
| */ |
| if (unlikely(clen > max_zpage_size)) { |
| clen = PAGE_SIZE; |
| page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM); |
| if (unlikely(!page_store)) { |
| mutex_unlock(&zram->lock); |
| pr_info("Error allocating memory for " |
| "incompressible page: %u\n", index); |
| zram_stat64_inc(zram, |
| &zram->stats.failed_writes); |
| goto out; |
| } |
| |
| offset = 0; |
| zram_set_flag(zram, index, ZRAM_UNCOMPRESSED); |
| zram_stat_inc(&zram->stats.pages_expand); |
| zram->table[index].page = page_store; |
| src = kmap_atomic(page, KM_USER0); |
| goto memstore; |
| } |
| |
| if (xv_malloc(zram->mem_pool, clen + sizeof(*zheader), |
| &zram->table[index].page, &offset, |
| GFP_NOIO | __GFP_HIGHMEM)) { |
| mutex_unlock(&zram->lock); |
| pr_info("Error allocating memory for compressed " |
| "page: %u, size=%zu\n", index, clen); |
| zram_stat64_inc(zram, &zram->stats.failed_writes); |
| goto out; |
| } |
| |
| memstore: |
| zram->table[index].offset = offset; |
| |
| cmem = kmap_atomic(zram->table[index].page, KM_USER1) + |
| zram->table[index].offset; |
| |
| #if 0 |
| /* Back-reference needed for memory defragmentation */ |
| if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) { |
| zheader = (struct zobj_header *)cmem; |
| zheader->table_idx = index; |
| cmem += sizeof(*zheader); |
| } |
| #endif |
| |
| memcpy(cmem, src, clen); |
| |
| kunmap_atomic(cmem, KM_USER1); |
| if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) |
| kunmap_atomic(src, KM_USER0); |
| |
| /* Update stats */ |
| zram_stat64_add(zram, &zram->stats.compr_size, clen); |
| zram_stat_inc(&zram->stats.pages_stored); |
| if (clen <= PAGE_SIZE / 2) |
| zram_stat_inc(&zram->stats.good_compress); |
| |
| mutex_unlock(&zram->lock); |
| index++; |
| } |
| |
| set_bit(BIO_UPTODATE, &bio->bi_flags); |
| bio_endio(bio, 0); |
| return 0; |
| |
| out: |
| bio_io_error(bio); |
| return 0; |
| } |
| |
| /* |
| * Check if request is within bounds and page aligned. |
| */ |
| static inline int valid_io_request(struct zram *zram, struct bio *bio) |
| { |
| if (unlikely( |
| (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) || |
| (bio->bi_sector & (SECTORS_PER_PAGE - 1)) || |
| (bio->bi_size & (PAGE_SIZE - 1)))) { |
| |
| return 0; |
| } |
| |
| /* I/O request is valid */ |
| return 1; |
| } |
| |
| /* |
| * Handler function for all zram I/O requests. |
| */ |
| static int zram_make_request(struct request_queue *queue, struct bio *bio) |
| { |
| int ret = 0; |
| struct zram *zram = queue->queuedata; |
| |
| if (!valid_io_request(zram, bio)) { |
| zram_stat64_inc(zram, &zram->stats.invalid_io); |
| bio_io_error(bio); |
| return 0; |
| } |
| |
| switch (bio_data_dir(bio)) { |
| case READ: |
| ret = zram_read(zram, bio); |
| break; |
| |
| case WRITE: |
| ret = zram_write(zram, bio); |
| break; |
| } |
| |
| return ret; |
| } |
| |
| void zram_reset_device(struct zram *zram) |
| { |
| size_t index; |
| |
| mutex_lock(&zram->init_lock); |
| zram->init_done = 0; |
| |
| /* Free various per-device buffers */ |
| kfree(zram->compress_workmem); |
| free_pages((unsigned long)zram->compress_buffer, 1); |
| |
| zram->compress_workmem = NULL; |
| zram->compress_buffer = NULL; |
| |
| /* Free all pages that are still in this zram device */ |
| for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) { |
| struct page *page; |
| u16 offset; |
| |
| page = zram->table[index].page; |
| offset = zram->table[index].offset; |
| |
| if (!page) |
| continue; |
| |
| if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) |
| __free_page(page); |
| else |
| xv_free(zram->mem_pool, page, offset); |
| } |
| |
| vfree(zram->table); |
| zram->table = NULL; |
| |
| xv_destroy_pool(zram->mem_pool); |
| zram->mem_pool = NULL; |
| |
| /* Reset stats */ |
| memset(&zram->stats, 0, sizeof(zram->stats)); |
| |
| zram->disksize = 0; |
| mutex_unlock(&zram->init_lock); |
| } |
| |
| int zram_init_device(struct zram *zram) |
| { |
| int ret; |
| size_t num_pages; |
| |
| mutex_lock(&zram->init_lock); |
| |
| if (zram->init_done) { |
| mutex_unlock(&zram->init_lock); |
| return 0; |
| } |
| |
| zram_set_disksize(zram, totalram_pages << PAGE_SHIFT); |
| |
| zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); |
| if (!zram->compress_workmem) { |
| pr_err("Error allocating compressor working memory!\n"); |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| zram->compress_buffer = (void *)__get_free_pages(__GFP_ZERO, 1); |
| if (!zram->compress_buffer) { |
| pr_err("Error allocating compressor buffer space\n"); |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| num_pages = zram->disksize >> PAGE_SHIFT; |
| zram->table = vmalloc(num_pages * sizeof(*zram->table)); |
| if (!zram->table) { |
| pr_err("Error allocating zram address table\n"); |
| /* To prevent accessing table entries during cleanup */ |
| zram->disksize = 0; |
| ret = -ENOMEM; |
| goto fail; |
| } |
| memset(zram->table, 0, num_pages * sizeof(*zram->table)); |
| |
| set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT); |
| |
| /* zram devices sort of resembles non-rotational disks */ |
| queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue); |
| |
| zram->mem_pool = xv_create_pool(); |
| if (!zram->mem_pool) { |
| pr_err("Error creating memory pool\n"); |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| zram->init_done = 1; |
| mutex_unlock(&zram->init_lock); |
| |
| pr_debug("Initialization done!\n"); |
| return 0; |
| |
| fail: |
| mutex_unlock(&zram->init_lock); |
| zram_reset_device(zram); |
| |
| pr_err("Initialization failed: err=%d\n", ret); |
| return ret; |
| } |
| |
| void zram_slot_free_notify(struct block_device *bdev, unsigned long index) |
| { |
| struct zram *zram; |
| |
| zram = bdev->bd_disk->private_data; |
| zram_free_page(zram, index); |
| zram_stat64_inc(zram, &zram->stats.notify_free); |
| } |
| |
| static const struct block_device_operations zram_devops = { |
| .swap_slot_free_notify = zram_slot_free_notify, |
| .owner = THIS_MODULE |
| }; |
| |
| static int create_device(struct zram *zram, int device_id) |
| { |
| int ret = 0; |
| |
| mutex_init(&zram->lock); |
| mutex_init(&zram->init_lock); |
| spin_lock_init(&zram->stat64_lock); |
| |
| zram->queue = blk_alloc_queue(GFP_KERNEL); |
| if (!zram->queue) { |
| pr_err("Error allocating disk queue for device %d\n", |
| device_id); |
| ret = -ENOMEM; |
| 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) { |
| blk_cleanup_queue(zram->queue); |
| pr_warning("Error allocating disk structure for device %d\n", |
| device_id); |
| ret = -ENOMEM; |
| goto out; |
| } |
| |
| 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<id>/disksize */ |
| set_capacity(zram->disk, 0); |
| |
| /* |
| * 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, PAGE_SIZE); |
| blk_queue_io_min(zram->disk->queue, PAGE_SIZE); |
| blk_queue_io_opt(zram->disk->queue, PAGE_SIZE); |
| |
| add_disk(zram->disk); |
| |
| #ifdef CONFIG_SYSFS |
| ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj, |
| &zram_disk_attr_group); |
| if (ret < 0) { |
| pr_warning("Error creating sysfs group"); |
| goto out; |
| } |
| #endif |
| |
| zram->init_done = 0; |
| |
| out: |
| return ret; |
| } |
| |
| static void destroy_device(struct zram *zram) |
| { |
| #ifdef CONFIG_SYSFS |
| sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, |
| &zram_disk_attr_group); |
| #endif |
| |
| if (zram->disk) { |
| del_gendisk(zram->disk); |
| put_disk(zram->disk); |
| } |
| |
| if (zram->queue) |
| blk_cleanup_queue(zram->queue); |
| } |
| |
| static int __init zram_init(void) |
| { |
| int ret, dev_id; |
| |
| if (num_devices > max_num_devices) { |
| pr_warning("Invalid value for num_devices: %u\n", |
| num_devices); |
| ret = -EINVAL; |
| goto out; |
| } |
| |
| zram_major = register_blkdev(0, "zram"); |
| if (zram_major <= 0) { |
| pr_warning("Unable to get major number\n"); |
| ret = -EBUSY; |
| goto out; |
| } |
| |
| if (!num_devices) { |
| pr_info("num_devices not specified. Using default: 1\n"); |
| num_devices = 1; |
| } |
| |
| /* Allocate the device array and initialize each one */ |
| pr_info("Creating %u devices ...\n", num_devices); |
| devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL); |
| if (!devices) { |
| ret = -ENOMEM; |
| goto unregister; |
| } |
| |
| for (dev_id = 0; dev_id < num_devices; dev_id++) { |
| ret = create_device(&devices[dev_id], dev_id); |
| if (ret) |
| goto free_devices; |
| } |
| |
| return 0; |
| |
| free_devices: |
| while (dev_id) |
| destroy_device(&devices[--dev_id]); |
| kfree(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 = &devices[i]; |
| |
| destroy_device(zram); |
| if (zram->init_done) |
| zram_reset_device(zram); |
| } |
| |
| unregister_blkdev(zram_major, "zram"); |
| |
| kfree(devices); |
| pr_debug("Cleanup done!\n"); |
| } |
| |
| module_param(num_devices, uint, 0); |
| MODULE_PARM_DESC(num_devices, "Number of zram devices"); |
| |
| module_init(zram_init); |
| module_exit(zram_exit); |
| |
| MODULE_LICENSE("Dual BSD/GPL"); |
| MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>"); |
| MODULE_DESCRIPTION("Compressed RAM Block Device"); |