diff options
Diffstat (limited to 'drivers/staging/zram/zram_drv.c')
-rw-r--r-- | drivers/staging/zram/zram_drv.c | 743 |
1 files changed, 743 insertions, 0 deletions
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c new file mode 100644 index 000000000000..8c3c057aa847 --- /dev/null +++ b/drivers/staging/zram/zram_drv.c @@ -0,0 +1,743 @@ +/* + * 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 (unlikely(!zram->init_done)) { + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + } + + 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"); |