diff options
Diffstat (limited to 'drivers/block/zram/zram_drv.c')
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 1322 |
1 files changed, 1322 insertions, 0 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c new file mode 100644 index 000000000..6e134f475 --- /dev/null +++ b/drivers/block/zram/zram_drv.c @@ -0,0 +1,1322 @@ +/* + * 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 <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/string.h> +#include <linux/vmalloc.h> +#include <linux/err.h> + +#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; + +static inline void deprecated_attr_warn(const char *name) +{ + pr_warn_once("%d (%s) Attribute %s (and others) will be removed. %s\n", + task_pid_nr(current), + current->comm, + name, + "See zram documentation."); +} + +#define ZRAM_ATTR_RO(name) \ +static ssize_t name##_show(struct device *d, \ + struct device_attribute *attr, char *b) \ +{ \ + struct zram *zram = dev_to_zram(d); \ + \ + deprecated_attr_warn(__stringify(name)); \ + return scnprintf(b, PAGE_SIZE, "%llu\n", \ + (u64)atomic64_read(&zram->stats.name)); \ +} \ +static DEVICE_ATTR_RO(name); + +static inline bool init_done(struct zram *zram) +{ + return zram->disksize; +} + +static inline struct zram *dev_to_zram(struct device *dev) +{ + return (struct zram *)dev_to_disk(dev)->private_data; +} + +static ssize_t compact_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + unsigned long nr_migrated; + struct zram *zram = dev_to_zram(dev); + struct zram_meta *meta; + + down_read(&zram->init_lock); + if (!init_done(zram)) { + up_read(&zram->init_lock); + return -EINVAL; + } + + meta = zram->meta; + nr_migrated = zs_compact(meta->mem_pool); + atomic64_add(nr_migrated, &zram->stats.num_migrated); + up_read(&zram->init_lock); + + return len; +} + +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); + + deprecated_attr_warn("orig_data_size"); + 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); + + deprecated_attr_warn("mem_used_total"); + down_read(&zram->init_lock); + if (init_done(zram)) { + struct zram_meta *meta = zram->meta; + 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 mem_limit_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + u64 val; + struct zram *zram = dev_to_zram(dev); + + deprecated_attr_warn("mem_limit"); + down_read(&zram->init_lock); + val = zram->limit_pages; + up_read(&zram->init_lock); + + return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT); +} + +static ssize_t mem_limit_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + u64 limit; + char *tmp; + struct zram *zram = dev_to_zram(dev); + + limit = memparse(buf, &tmp); + if (buf == tmp) /* no chars parsed, invalid input */ + return -EINVAL; + + down_write(&zram->init_lock); + zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT; + up_write(&zram->init_lock); + + return len; +} + +static ssize_t mem_used_max_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + u64 val = 0; + struct zram *zram = dev_to_zram(dev); + + deprecated_attr_warn("mem_used_max"); + down_read(&zram->init_lock); + if (init_done(zram)) + val = atomic_long_read(&zram->stats.max_used_pages); + up_read(&zram->init_lock); + + return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT); +} + +static ssize_t mem_used_max_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + int err; + unsigned long val; + struct zram *zram = dev_to_zram(dev); + + err = kstrtoul(buf, 10, &val); + if (err || val != 0) + return -EINVAL; + + down_read(&zram->init_lock); + if (init_done(zram)) { + struct zram_meta *meta = zram->meta; + atomic_long_set(&zram->stats.max_used_pages, + zs_get_total_pages(meta->mem_pool)); + } + up_read(&zram->init_lock); + + return len; +} + +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, + sector_t start, unsigned int size) +{ + u64 end, bound; + + /* unaligned request */ + if (unlikely(start & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1))) + return 0; + if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1))) + return 0; + + end = start + (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, u64 disksize) +{ + size_t num_pages = disksize >> PAGE_SHIFT; + size_t index; + + /* Free all pages that are still in this zram device */ + for (index = 0; index < num_pages; index++) { + unsigned long handle = meta->table[index].handle; + + if (!handle) + continue; + + zs_free(meta->mem_pool, handle); + } + + zs_destroy_pool(meta->mem_pool); + vfree(meta->table); + kfree(meta); +} + +static struct zram_meta *zram_meta_alloc(int device_id, u64 disksize) +{ + size_t num_pages; + char pool_name[8]; + struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL); + + if (!meta) + return NULL; + + 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 out_error; + } + + snprintf(pool_name, sizeof(pool_name), "zram%d", device_id); + meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO | __GFP_HIGHMEM); + if (!meta->mem_pool) { + pr_err("Error creating memory pool\n"); + goto out_error; + } + + return meta; + +out_error: + vfree(meta->table); + kfree(meta); + return NULL; +} + +static inline bool zram_meta_get(struct zram *zram) +{ + if (atomic_inc_not_zero(&zram->refcount)) + return true; + return false; +} + +static inline void zram_meta_put(struct zram *zram) +{ + atomic_dec(&zram->refcount); +} + +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) +{ + 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 inline void update_used_max(struct zram *zram, + const unsigned long pages) +{ + unsigned long old_max, cur_max; + + old_max = atomic_long_read(&zram->stats.max_used_pages); + + do { + cur_max = old_max; + if (pages > cur_max) + old_max = atomic_long_cmpxchg( + &zram->stats.max_used_pages, cur_max, pages); + } while (old_max != cur_max); +} + +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; + unsigned long alloced_pages; + + 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)) { + if (user_mem) + 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; + } + + alloced_pages = zs_get_total_pages(meta->mem_pool); + if (zram->limit_pages && alloced_pages > zram->limit_pages) { + zs_free(meta->mem_pool, handle); + ret = -ENOMEM; + goto out; + } + + update_used_max(zram, alloced_pages); + + 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, int rw) +{ + unsigned long start_time = jiffies; + int ret; + + generic_start_io_acct(rw, bvec->bv_len >> SECTOR_SHIFT, + &zram->disk->part0); + + if (rw == READ) { + atomic64_inc(&zram->stats.num_reads); + ret = zram_bvec_read(zram, bvec, index, offset); + } else { + atomic64_inc(&zram->stats.num_writes); + ret = zram_bvec_write(zram, bvec, index, offset); + } + + generic_end_io_acct(rw, &zram->disk->part0, start_time); + + 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); + atomic64_inc(&zram->stats.notify_free); + index++; + n -= PAGE_SIZE; + } +} + +static void zram_reset_device(struct zram *zram) +{ + struct zram_meta *meta; + struct zcomp *comp; + u64 disksize; + + down_write(&zram->init_lock); + + zram->limit_pages = 0; + + if (!init_done(zram)) { + up_write(&zram->init_lock); + return; + } + + meta = zram->meta; + comp = zram->comp; + disksize = zram->disksize; + /* + * Refcount will go down to 0 eventually and r/w handler + * cannot handle further I/O so it will bail out by + * check zram_meta_get. + */ + zram_meta_put(zram); + /* + * We want to free zram_meta in process context to avoid + * deadlock between reclaim path and any other locks. + */ + wait_event(zram->io_done, atomic_read(&zram->refcount) == 0); + + /* Reset stats */ + memset(&zram->stats, 0, sizeof(zram->stats)); + zram->disksize = 0; + zram->max_comp_streams = 1; + + set_capacity(zram->disk, 0); + part_stat_set_all(&zram->disk->part0, 0); + + up_write(&zram->init_lock); + /* I/O operation under all of CPU are done so let's free */ + zram_meta_free(meta, disksize); + zcomp_destroy(comp); +} + +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(zram->disk->first_minor, 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; + } + + init_waitqueue_head(&zram->io_done); + atomic_set(&zram->refcount, 1); + 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, disksize); + 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; + + mutex_lock(&bdev->bd_mutex); + /* Do not reset an active device! */ + if (bdev->bd_openers) { + 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); + zram_reset_device(zram); + + mutex_unlock(&bdev->bd_mutex); + revalidate_disk(zram->disk); + bdput(bdev); + + return len; + +out: + mutex_unlock(&bdev->bd_mutex); + bdput(bdev); + return ret; +} + +static void __zram_make_request(struct zram *zram, struct bio *bio) +{ + int offset, rw; + 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; + } + + rw = bio_data_dir(bio); + 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, rw) < 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, rw) < 0) + goto out; + } else + if (zram_bvec_rw(zram, &bvec, index, offset, rw) < 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; + + if (unlikely(!zram_meta_get(zram))) + goto error; + + if (!valid_io_request(zram, bio->bi_iter.bi_sector, + bio->bi_iter.bi_size)) { + atomic64_inc(&zram->stats.invalid_io); + goto put_zram; + } + + __zram_make_request(zram, bio); + zram_meta_put(zram); + return; +put_zram: + zram_meta_put(zram); +error: + 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 int zram_rw_page(struct block_device *bdev, sector_t sector, + struct page *page, int rw) +{ + int offset, err = -EIO; + u32 index; + struct zram *zram; + struct bio_vec bv; + + zram = bdev->bd_disk->private_data; + if (unlikely(!zram_meta_get(zram))) + goto out; + + if (!valid_io_request(zram, sector, PAGE_SIZE)) { + atomic64_inc(&zram->stats.invalid_io); + err = -EINVAL; + goto put_zram; + } + + index = sector >> SECTORS_PER_PAGE_SHIFT; + offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT; + + bv.bv_page = page; + bv.bv_len = PAGE_SIZE; + bv.bv_offset = 0; + + err = zram_bvec_rw(zram, &bv, index, offset, rw); +put_zram: + zram_meta_put(zram); +out: + /* + * If I/O fails, just return error(ie, non-zero) without + * calling page_endio. + * It causes resubmit the I/O with bio request by upper functions + * of rw_page(e.g., swap_readpage, __swap_writepage) and + * bio->bi_end_io does things to handle the error + * (e.g., SetPageError, set_page_dirty and extra works). + */ + if (err == 0) + page_endio(page, rw, 0); + return err; +} + +static const struct block_device_operations zram_devops = { + .swap_slot_free_notify = zram_slot_free_notify, + .rw_page = zram_rw_page, + .owner = THIS_MODULE +}; + +static DEVICE_ATTR_WO(compact); +static DEVICE_ATTR_RW(disksize); +static DEVICE_ATTR_RO(initstate); +static DEVICE_ATTR_WO(reset); +static DEVICE_ATTR_RO(orig_data_size); +static DEVICE_ATTR_RO(mem_used_total); +static DEVICE_ATTR_RW(mem_limit); +static DEVICE_ATTR_RW(mem_used_max); +static DEVICE_ATTR_RW(max_comp_streams); +static DEVICE_ATTR_RW(comp_algorithm); + +static ssize_t io_stat_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct zram *zram = dev_to_zram(dev); + ssize_t ret; + + down_read(&zram->init_lock); + ret = scnprintf(buf, PAGE_SIZE, + "%8llu %8llu %8llu %8llu\n", + (u64)atomic64_read(&zram->stats.failed_reads), + (u64)atomic64_read(&zram->stats.failed_writes), + (u64)atomic64_read(&zram->stats.invalid_io), + (u64)atomic64_read(&zram->stats.notify_free)); + up_read(&zram->init_lock); + + return ret; +} + +static ssize_t mm_stat_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct zram *zram = dev_to_zram(dev); + u64 orig_size, mem_used = 0; + long max_used; + ssize_t ret; + + down_read(&zram->init_lock); + if (init_done(zram)) + mem_used = zs_get_total_pages(zram->meta->mem_pool); + + orig_size = atomic64_read(&zram->stats.pages_stored); + max_used = atomic_long_read(&zram->stats.max_used_pages); + + ret = scnprintf(buf, PAGE_SIZE, + "%8llu %8llu %8llu %8lu %8ld %8llu %8llu\n", + orig_size << PAGE_SHIFT, + (u64)atomic64_read(&zram->stats.compr_data_size), + mem_used << PAGE_SHIFT, + zram->limit_pages << PAGE_SHIFT, + max_used << PAGE_SHIFT, + (u64)atomic64_read(&zram->stats.zero_pages), + (u64)atomic64_read(&zram->stats.num_migrated)); + up_read(&zram->init_lock); + + return ret; +} + +static DEVICE_ATTR_RO(io_stat); +static DEVICE_ATTR_RO(mm_stat); +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_compact.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_mem_limit.attr, + &dev_attr_mem_used_max.attr, + &dev_attr_max_comp_streams.attr, + &dev_attr_comp_algorithm.attr, + &dev_attr_io_stat.attr, + &dev_attr_mm_stat.attr, + NULL, +}; + +static struct attribute_group zram_disk_attr_group = { + .attrs = zram_disk_attrs, +}; + +static int create_device(struct zram *zram, int device_id) +{ + struct request_queue *queue; + int ret = -ENOMEM; + + init_rwsem(&zram->init_lock); + + queue = blk_alloc_queue(GFP_KERNEL); + if (!queue) { + pr_err("Error allocating disk queue for device %d\n", + device_id); + goto out; + } + + blk_queue_make_request(queue, zram_make_request); + + /* gendisk structure */ + zram->disk = alloc_disk(1); + if (!zram->disk) { + pr_warn("Error allocating disk structure for device %d\n", + device_id); + ret = -ENOMEM; + goto out_free_queue; + } + + zram->disk->major = zram_major; + zram->disk->first_minor = device_id; + zram->disk->fops = &zram_devops; + zram->disk->queue = queue; + zram->disk->queue->queuedata = zram; + 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); + /* zram devices sort of resembles non-rotational disks */ + queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue); + queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, 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(queue); +out: + return ret; +} + +static void destroy_devices(unsigned int nr) +{ + struct zram *zram; + unsigned int i; + + for (i = 0; i < nr; i++) { + zram = &zram_devices[i]; + /* + * Remove sysfs first, so no one will perform a disksize + * store while we destroy the devices + */ + sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, + &zram_disk_attr_group); + + zram_reset_device(zram); + + blk_cleanup_queue(zram->disk->queue); + del_gendisk(zram->disk); + put_disk(zram->disk); + } + + kfree(zram_devices); + unregister_blkdev(zram_major, "zram"); + pr_info("Destroyed %u device(s)\n", nr); +} + +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); + return -EINVAL; + } + + zram_major = register_blkdev(0, "zram"); + if (zram_major <= 0) { + pr_warn("Unable to get major number\n"); + return -EBUSY; + } + + /* Allocate the device array and initialize each one */ + zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL); + if (!zram_devices) { + unregister_blkdev(zram_major, "zram"); + return -ENOMEM; + } + + for (dev_id = 0; dev_id < num_devices; dev_id++) { + ret = create_device(&zram_devices[dev_id], dev_id); + if (ret) + goto out_error; + } + + pr_info("Created %u device(s)\n", num_devices); + return 0; + +out_error: + destroy_devices(dev_id); + return ret; +} + +static void __exit zram_exit(void) +{ + destroy_devices(num_devices); +} + +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 <ngupta@vflare.org>"); +MODULE_DESCRIPTION("Compressed RAM Block Device"); |