/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "zram_drv.h" static DEFINE_IDR(zram_index_idr); /* idr index must be protected */ static DEFINE_MUTEX(zram_index_mutex); static int zram_major; static const char *default_compressor = CONFIG_ZRAM_DEF_COMP; /* Module params (documentation at end) */ static unsigned int num_devices = 1; /* * Pages that compress to sizes equals or greater than this are stored * uncompressed in memory. */ static size_t huge_class_size; static const struct block_device_operations zram_devops; static const struct block_device_operations zram_wb_devops; static void zram_free_page(struct zram *zram, size_t index); static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, u32 index, int offset, struct bio *bio); static int zram_slot_trylock(struct zram *zram, u32 index) { return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].flags); } static void zram_slot_lock(struct zram *zram, u32 index) { bit_spin_lock(ZRAM_LOCK, &zram->table[index].flags); } static void zram_slot_unlock(struct zram *zram, u32 index) { bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags); } 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 unsigned long zram_get_handle(struct zram *zram, u32 index) { return zram->table[index].handle; } static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle) { zram->table[index].handle = handle; } /* flag operations require table entry bit_spin_lock() being held */ static bool 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 inline void zram_set_element(struct zram *zram, u32 index, unsigned long element) { zram->table[index].element = element; } static unsigned long zram_get_element(struct zram *zram, u32 index) { return zram->table[index].element; } static size_t zram_get_obj_size(struct zram *zram, u32 index) { return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1); } static void zram_set_obj_size(struct zram *zram, u32 index, size_t size) { unsigned long flags = zram->table[index].flags >> ZRAM_FLAG_SHIFT; zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size; } static inline bool zram_allocated(struct zram *zram, u32 index) { return zram_get_obj_size(zram, index) || zram_test_flag(zram, index, ZRAM_SAME) || zram_test_flag(zram, index, ZRAM_WB); } #if PAGE_SIZE != 4096 static inline bool is_partial_io(struct bio_vec *bvec) { return bvec->bv_len != PAGE_SIZE; } #else static inline bool is_partial_io(struct bio_vec *bvec) { return false; } #endif /* * Check if request is within bounds and aligned on zram logical blocks. */ static inline bool 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 false; if (unlikely(size & (ZRAM_LOGICAL_BLOCK_SIZE - 1))) return false; end = start + (size >> SECTOR_SHIFT); bound = zram->disksize >> SECTOR_SHIFT; /* out of range range */ if (unlikely(start >= bound || end > bound || start > end)) return false; /* I/O request is valid */ return true; } static void update_position(u32 *index, int *offset, struct bio_vec *bvec) { *index += (*offset + bvec->bv_len) / PAGE_SIZE; *offset = (*offset + bvec->bv_len) % PAGE_SIZE; } 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 inline void zram_fill_page(void *ptr, unsigned long len, unsigned long value) { WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long))); memset_l(ptr, value, len / sizeof(unsigned long)); } static bool page_same_filled(void *ptr, unsigned long *element) { unsigned long *page; unsigned long val; unsigned int pos, last_pos = PAGE_SIZE / sizeof(*page) - 1; page = (unsigned long *)ptr; val = page[0]; if (val != page[last_pos]) return false; for (pos = 1; pos < last_pos; pos++) { if (val != page[pos]) return false; } *element = val; return true; } 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 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 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_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)) { atomic_long_set(&zram->stats.max_used_pages, zs_get_total_pages(zram->mem_pool)); } up_read(&zram->init_lock); return len; } /* * Mark all pages which are older than or equal to cutoff as IDLE. * Callers should hold the zram init lock in read mode */ static void mark_idle(struct zram *zram, ktime_t cutoff) { int is_idle = 1; unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; int index; for (index = 0; index < nr_pages; index++) { /* * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race. * See the comment in writeback_store. */ zram_slot_lock(zram, index); if (zram_allocated(zram, index) && !zram_test_flag(zram, index, ZRAM_UNDER_WB)) { #ifdef CONFIG_ZRAM_MEMORY_TRACKING is_idle = !cutoff || ktime_after(cutoff, zram->table[index].ac_time); #endif if (is_idle) zram_set_flag(zram, index, ZRAM_IDLE); } zram_slot_unlock(zram, index); } } static ssize_t idle_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); ktime_t cutoff_time = 0; ssize_t rv = -EINVAL; if (!sysfs_streq(buf, "all")) { /* * If it did not parse as 'all' try to treat it as an integer when * we have memory tracking enabled. */ u64 age_sec; if (IS_ENABLED(CONFIG_ZRAM_MEMORY_TRACKING) && !kstrtoull(buf, 0, &age_sec)) cutoff_time = ktime_sub(ktime_get_boottime(), ns_to_ktime(age_sec * NSEC_PER_SEC)); else goto out; } down_read(&zram->init_lock); if (!init_done(zram)) goto out_unlock; /* A cutoff_time of 0 marks everything as idle, this is the "all" behavior */ mark_idle(zram, cutoff_time); rv = len; out_unlock: up_read(&zram->init_lock); out: return rv; } #ifdef CONFIG_ZRAM_WRITEBACK static ssize_t writeback_limit_enable_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); u64 val; ssize_t ret = -EINVAL; if (kstrtoull(buf, 10, &val)) return ret; down_read(&zram->init_lock); spin_lock(&zram->wb_limit_lock); zram->wb_limit_enable = val; spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); ret = len; return ret; } static ssize_t writeback_limit_enable_show(struct device *dev, struct device_attribute *attr, char *buf) { bool val; struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); spin_lock(&zram->wb_limit_lock); val = zram->wb_limit_enable; spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); return scnprintf(buf, PAGE_SIZE, "%d\n", val); } static ssize_t writeback_limit_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); u64 val; ssize_t ret = -EINVAL; if (kstrtoull(buf, 10, &val)) return ret; down_read(&zram->init_lock); spin_lock(&zram->wb_limit_lock); zram->bd_wb_limit = val; spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); ret = len; return ret; } static ssize_t writeback_limit_show(struct device *dev, struct device_attribute *attr, char *buf) { u64 val; struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); spin_lock(&zram->wb_limit_lock); val = zram->bd_wb_limit; spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); return scnprintf(buf, PAGE_SIZE, "%llu\n", val); } static void reset_bdev(struct zram *zram) { struct block_device *bdev; if (!zram->backing_dev) return; bdev = zram->bdev; blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); /* hope filp_close flush all of IO */ filp_close(zram->backing_dev, NULL); zram->backing_dev = NULL; zram->bdev = NULL; zram->disk->fops = &zram_devops; kvfree(zram->bitmap); zram->bitmap = NULL; } static ssize_t backing_dev_show(struct device *dev, struct device_attribute *attr, char *buf) { struct file *file; struct zram *zram = dev_to_zram(dev); char *p; ssize_t ret; down_read(&zram->init_lock); file = zram->backing_dev; if (!file) { memcpy(buf, "none\n", 5); up_read(&zram->init_lock); return 5; } p = file_path(file, buf, PAGE_SIZE - 1); if (IS_ERR(p)) { ret = PTR_ERR(p); goto out; } ret = strlen(p); memmove(buf, p, ret); buf[ret++] = '\n'; out: up_read(&zram->init_lock); return ret; } static ssize_t backing_dev_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { char *file_name; size_t sz; struct file *backing_dev = NULL; struct inode *inode; struct address_space *mapping; unsigned int bitmap_sz; unsigned long nr_pages, *bitmap = NULL; struct block_device *bdev = NULL; int err; struct zram *zram = dev_to_zram(dev); file_name = kmalloc(PATH_MAX, GFP_KERNEL); if (!file_name) return -ENOMEM; down_write(&zram->init_lock); if (init_done(zram)) { pr_info("Can't setup backing device for initialized device\n"); err = -EBUSY; goto out; } strlcpy(file_name, buf, PATH_MAX); /* ignore trailing newline */ sz = strlen(file_name); if (sz > 0 && file_name[sz - 1] == '\n') file_name[sz - 1] = 0x00; backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0); if (IS_ERR(backing_dev)) { err = PTR_ERR(backing_dev); backing_dev = NULL; goto out; } mapping = backing_dev->f_mapping; inode = mapping->host; /* Support only block device in this moment */ if (!S_ISBLK(inode->i_mode)) { err = -ENOTBLK; goto out; } bdev = blkdev_get_by_dev(inode->i_rdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram); if (IS_ERR(bdev)) { err = PTR_ERR(bdev); bdev = NULL; goto out; } nr_pages = i_size_read(inode) >> PAGE_SHIFT; bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long); bitmap = kvzalloc(bitmap_sz, GFP_KERNEL); if (!bitmap) { err = -ENOMEM; goto out; } reset_bdev(zram); zram->bdev = bdev; zram->backing_dev = backing_dev; zram->bitmap = bitmap; zram->nr_pages = nr_pages; /* * With writeback feature, zram does asynchronous IO so it's no longer * synchronous device so let's remove synchronous io flag. Othewise, * upper layer(e.g., swap) could wait IO completion rather than * (submit and return), which will cause system sluggish. * Furthermore, when the IO function returns(e.g., swap_readpage), * upper layer expects IO was done so it could deallocate the page * freely but in fact, IO is going on so finally could cause * use-after-free when the IO is really done. */ zram->disk->fops = &zram_wb_devops; up_write(&zram->init_lock); pr_info("setup backing device %s\n", file_name); kfree(file_name); return len; out: kvfree(bitmap); if (bdev) blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); if (backing_dev) filp_close(backing_dev, NULL); up_write(&zram->init_lock); kfree(file_name); return err; } static unsigned long alloc_block_bdev(struct zram *zram) { unsigned long blk_idx = 1; retry: /* skip 0 bit to confuse zram.handle = 0 */ blk_idx = find_next_zero_bit(zram->bitmap, zram->nr_pages, blk_idx); if (blk_idx == zram->nr_pages) return 0; if (test_and_set_bit(blk_idx, zram->bitmap)) goto retry; atomic64_inc(&zram->stats.bd_count); return blk_idx; } static void free_block_bdev(struct zram *zram, unsigned long blk_idx) { int was_set; was_set = test_and_clear_bit(blk_idx, zram->bitmap); WARN_ON_ONCE(!was_set); atomic64_dec(&zram->stats.bd_count); } static void zram_page_end_io(struct bio *bio) { struct page *page = bio_first_page_all(bio); page_endio(page, op_is_write(bio_op(bio)), blk_status_to_errno(bio->bi_status)); bio_put(bio); } /* * Returns 1 if the submission is successful. */ static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec, unsigned long entry, struct bio *parent) { struct bio *bio; bio = bio_alloc(zram->bdev, 1, parent ? parent->bi_opf : REQ_OP_READ, GFP_NOIO); if (!bio) return -ENOMEM; bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9); if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, bvec->bv_offset)) { bio_put(bio); return -EIO; } if (!parent) bio->bi_end_io = zram_page_end_io; else bio_chain(bio, parent); submit_bio(bio); return 1; } #define PAGE_WB_SIG "page_index=" #define PAGE_WRITEBACK 0 #define HUGE_WRITEBACK (1<<0) #define IDLE_WRITEBACK (1<<1) static ssize_t writeback_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; unsigned long index = 0; struct bio bio; struct bio_vec bio_vec; struct page *page; ssize_t ret = len; int mode, err; unsigned long blk_idx = 0; if (sysfs_streq(buf, "idle")) mode = IDLE_WRITEBACK; else if (sysfs_streq(buf, "huge")) mode = HUGE_WRITEBACK; else if (sysfs_streq(buf, "huge_idle")) mode = IDLE_WRITEBACK | HUGE_WRITEBACK; else { if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1)) return -EINVAL; if (kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index) || index >= nr_pages) return -EINVAL; nr_pages = 1; mode = PAGE_WRITEBACK; } down_read(&zram->init_lock); if (!init_done(zram)) { ret = -EINVAL; goto release_init_lock; } if (!zram->backing_dev) { ret = -ENODEV; goto release_init_lock; } page = alloc_page(GFP_KERNEL); if (!page) { ret = -ENOMEM; goto release_init_lock; } for (; nr_pages != 0; index++, nr_pages--) { struct bio_vec bvec; bvec.bv_page = page; bvec.bv_len = PAGE_SIZE; bvec.bv_offset = 0; spin_lock(&zram->wb_limit_lock); if (zram->wb_limit_enable && !zram->bd_wb_limit) { spin_unlock(&zram->wb_limit_lock); ret = -EIO; break; } spin_unlock(&zram->wb_limit_lock); if (!blk_idx) { blk_idx = alloc_block_bdev(zram); if (!blk_idx) { ret = -ENOSPC; break; } } zram_slot_lock(zram, index); if (!zram_allocated(zram, index)) goto next; if (zram_test_flag(zram, index, ZRAM_WB) || zram_test_flag(zram, index, ZRAM_SAME) || zram_test_flag(zram, index, ZRAM_UNDER_WB)) goto next; if (mode & IDLE_WRITEBACK && !zram_test_flag(zram, index, ZRAM_IDLE)) goto next; if (mode & HUGE_WRITEBACK && !zram_test_flag(zram, index, ZRAM_HUGE)) goto next; /* * Clearing ZRAM_UNDER_WB is duty of caller. * IOW, zram_free_page never clear it. */ zram_set_flag(zram, index, ZRAM_UNDER_WB); /* Need for hugepage writeback racing */ zram_set_flag(zram, index, ZRAM_IDLE); zram_slot_unlock(zram, index); if (zram_bvec_read(zram, &bvec, index, 0, NULL)) { zram_slot_lock(zram, index); zram_clear_flag(zram, index, ZRAM_UNDER_WB); zram_clear_flag(zram, index, ZRAM_IDLE); zram_slot_unlock(zram, index); continue; } bio_init(&bio, zram->bdev, &bio_vec, 1, REQ_OP_WRITE | REQ_SYNC); bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9); bio_add_page(&bio, bvec.bv_page, bvec.bv_len, bvec.bv_offset); /* * XXX: A single page IO would be inefficient for write * but it would be not bad as starter. */ err = submit_bio_wait(&bio); if (err) { zram_slot_lock(zram, index); zram_clear_flag(zram, index, ZRAM_UNDER_WB); zram_clear_flag(zram, index, ZRAM_IDLE); zram_slot_unlock(zram, index); /* * Return last IO error unless every IO were * not suceeded. */ ret = err; continue; } atomic64_inc(&zram->stats.bd_writes); /* * We released zram_slot_lock so need to check if the slot was * changed. If there is freeing for the slot, we can catch it * easily by zram_allocated. * A subtle case is the slot is freed/reallocated/marked as * ZRAM_IDLE again. To close the race, idle_store doesn't * mark ZRAM_IDLE once it found the slot was ZRAM_UNDER_WB. * Thus, we could close the race by checking ZRAM_IDLE bit. */ zram_slot_lock(zram, index); if (!zram_allocated(zram, index) || !zram_test_flag(zram, index, ZRAM_IDLE)) { zram_clear_flag(zram, index, ZRAM_UNDER_WB); zram_clear_flag(zram, index, ZRAM_IDLE); goto next; } zram_free_page(zram, index); zram_clear_flag(zram, index, ZRAM_UNDER_WB); zram_set_flag(zram, index, ZRAM_WB); zram_set_element(zram, index, blk_idx); blk_idx = 0; atomic64_inc(&zram->stats.pages_stored); spin_lock(&zram->wb_limit_lock); if (zram->wb_limit_enable && zram->bd_wb_limit > 0) zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12); spin_unlock(&zram->wb_limit_lock); next: zram_slot_unlock(zram, index); } if (blk_idx) free_block_bdev(zram, blk_idx); __free_page(page); release_init_lock: up_read(&zram->init_lock); return ret; } struct zram_work { struct work_struct work; struct zram *zram; unsigned long entry; struct bio *bio; struct bio_vec bvec; }; #if PAGE_SIZE != 4096 static void zram_sync_read(struct work_struct *work) { struct zram_work *zw = container_of(work, struct zram_work, work); struct zram *zram = zw->zram; unsigned long entry = zw->entry; struct bio *bio = zw->bio; read_from_bdev_async(zram, &zw->bvec, entry, bio); } /* * Block layer want one ->submit_bio to be active at a time, so if we use * chained IO with parent IO in same context, it's a deadlock. To avoid that, * use a worker thread context. */ static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec, unsigned long entry, struct bio *bio) { struct zram_work work; work.bvec = *bvec; work.zram = zram; work.entry = entry; work.bio = bio; INIT_WORK_ONSTACK(&work.work, zram_sync_read); queue_work(system_unbound_wq, &work.work); flush_work(&work.work); destroy_work_on_stack(&work.work); return 1; } #else static int read_from_bdev_sync(struct zram *zram, struct bio_vec *bvec, unsigned long entry, struct bio *bio) { WARN_ON(1); return -EIO; } #endif static int read_from_bdev(struct zram *zram, struct bio_vec *bvec, unsigned long entry, struct bio *parent, bool sync) { atomic64_inc(&zram->stats.bd_reads); if (sync) return read_from_bdev_sync(zram, bvec, entry, parent); else return read_from_bdev_async(zram, bvec, entry, parent); } #else static inline void reset_bdev(struct zram *zram) {}; static int read_from_bdev(struct zram *zram, struct bio_vec *bvec, unsigned long entry, struct bio *parent, bool sync) { return -EIO; } static void free_block_bdev(struct zram *zram, unsigned long blk_idx) {}; #endif #ifdef CONFIG_ZRAM_MEMORY_TRACKING static struct dentry *zram_debugfs_root; static void zram_debugfs_create(void) { zram_debugfs_root = debugfs_create_dir("zram", NULL); } static void zram_debugfs_destroy(void) { debugfs_remove_recursive(zram_debugfs_root); } static void zram_accessed(struct zram *zram, u32 index) { zram_clear_flag(zram, index, ZRAM_IDLE); zram->table[index].ac_time = ktime_get_boottime(); } static ssize_t read_block_state(struct file *file, char __user *buf, size_t count, loff_t *ppos) { char *kbuf; ssize_t index, written = 0; struct zram *zram = file->private_data; unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; struct timespec64 ts; kbuf = kvmalloc(count, GFP_KERNEL); if (!kbuf) return -ENOMEM; down_read(&zram->init_lock); if (!init_done(zram)) { up_read(&zram->init_lock); kvfree(kbuf); return -EINVAL; } for (index = *ppos; index < nr_pages; index++) { int copied; zram_slot_lock(zram, index); if (!zram_allocated(zram, index)) goto next; ts = ktime_to_timespec64(zram->table[index].ac_time); copied = snprintf(kbuf + written, count, "%12zd %12lld.%06lu %c%c%c%c\n", index, (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC, zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.', zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.', zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.', zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.'); if (count <= copied) { zram_slot_unlock(zram, index); break; } written += copied; count -= copied; next: zram_slot_unlock(zram, index); *ppos += 1; } up_read(&zram->init_lock); if (copy_to_user(buf, kbuf, written)) written = -EFAULT; kvfree(kbuf); return written; } static const struct file_operations proc_zram_block_state_op = { .open = simple_open, .read = read_block_state, .llseek = default_llseek, }; static void zram_debugfs_register(struct zram *zram) { if (!zram_debugfs_root) return; zram->debugfs_dir = debugfs_create_dir(zram->disk->disk_name, zram_debugfs_root); debugfs_create_file("block_state", 0400, zram->debugfs_dir, zram, &proc_zram_block_state_op); } static void zram_debugfs_unregister(struct zram *zram) { debugfs_remove_recursive(zram->debugfs_dir); } #else static void zram_debugfs_create(void) {}; static void zram_debugfs_destroy(void) {}; static void zram_accessed(struct zram *zram, u32 index) { zram_clear_flag(zram, index, ZRAM_IDLE); }; static void zram_debugfs_register(struct zram *zram) {}; static void zram_debugfs_unregister(struct zram *zram) {}; #endif /* * We switched to per-cpu streams and this attr is not needed anymore. * However, we will keep it around for some time, because: * a) we may revert per-cpu streams in the future * b) it's visible to user space and we need to follow our 2 years * retirement rule; but we already have a number of 'soon to be * altered' attrs, so max_comp_streams need to wait for the next * layoff cycle. */ static ssize_t max_comp_streams_show(struct device *dev, struct device_attribute *attr, char *buf) { return scnprintf(buf, PAGE_SIZE, "%d\n", num_online_cpus()); } static ssize_t max_comp_streams_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { return len; } 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); char compressor[ARRAY_SIZE(zram->compressor)]; size_t sz; strlcpy(compressor, buf, sizeof(compressor)); /* ignore trailing newline */ sz = strlen(compressor); if (sz > 0 && compressor[sz - 1] == '\n') compressor[sz - 1] = 0x00; if (!zcomp_available_algorithm(compressor)) return -EINVAL; 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; } strcpy(zram->compressor, compressor); up_write(&zram->init_lock); return len; } static ssize_t compact_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); if (!init_done(zram)) { up_read(&zram->init_lock); return -EINVAL; } zs_compact(zram->mem_pool); up_read(&zram->init_lock); return len; } 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); struct zs_pool_stats pool_stats; u64 orig_size, mem_used = 0; long max_used; ssize_t ret; memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats)); down_read(&zram->init_lock); if (init_done(zram)) { mem_used = zs_get_total_pages(zram->mem_pool); zs_pool_stats(zram->mem_pool, &pool_stats); } 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 %8lu %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.same_pages), atomic_long_read(&pool_stats.pages_compacted), (u64)atomic64_read(&zram->stats.huge_pages), (u64)atomic64_read(&zram->stats.huge_pages_since)); up_read(&zram->init_lock); return ret; } #ifdef CONFIG_ZRAM_WRITEBACK #define FOUR_K(x) ((x) * (1 << (PAGE_SHIFT - 12))) static ssize_t bd_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\n", FOUR_K((u64)atomic64_read(&zram->stats.bd_count)), FOUR_K((u64)atomic64_read(&zram->stats.bd_reads)), FOUR_K((u64)atomic64_read(&zram->stats.bd_writes))); up_read(&zram->init_lock); return ret; } #endif static ssize_t debug_stat_show(struct device *dev, struct device_attribute *attr, char *buf) { int version = 2; struct zram *zram = dev_to_zram(dev); ssize_t ret; down_read(&zram->init_lock); ret = scnprintf(buf, PAGE_SIZE, "version: %d\n%8llu\n", version, (u64)atomic64_read(&zram->stats.miss_free)); up_read(&zram->init_lock); return ret; } static DEVICE_ATTR_RO(io_stat); static DEVICE_ATTR_RO(mm_stat); #ifdef CONFIG_ZRAM_WRITEBACK static DEVICE_ATTR_RO(bd_stat); #endif static DEVICE_ATTR_RO(debug_stat); static void zram_meta_free(struct zram *zram, 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++) zram_free_page(zram, index); zs_destroy_pool(zram->mem_pool); vfree(zram->table); } static bool zram_meta_alloc(struct zram *zram, u64 disksize) { size_t num_pages; num_pages = disksize >> PAGE_SHIFT; zram->table = vzalloc(array_size(num_pages, sizeof(*zram->table))); if (!zram->table) return false; zram->mem_pool = zs_create_pool(zram->disk->disk_name); if (!zram->mem_pool) { vfree(zram->table); return false; } if (!huge_class_size) huge_class_size = zs_huge_class_size(zram->mem_pool); return true; } /* * 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) { unsigned long handle; #ifdef CONFIG_ZRAM_MEMORY_TRACKING zram->table[index].ac_time = 0; #endif if (zram_test_flag(zram, index, ZRAM_IDLE)) zram_clear_flag(zram, index, ZRAM_IDLE); if (zram_test_flag(zram, index, ZRAM_HUGE)) { zram_clear_flag(zram, index, ZRAM_HUGE); atomic64_dec(&zram->stats.huge_pages); } if (zram_test_flag(zram, index, ZRAM_WB)) { zram_clear_flag(zram, index, ZRAM_WB); free_block_bdev(zram, zram_get_element(zram, index)); goto out; } /* * No memory is allocated for same element filled pages. * Simply clear same page flag. */ if (zram_test_flag(zram, index, ZRAM_SAME)) { zram_clear_flag(zram, index, ZRAM_SAME); atomic64_dec(&zram->stats.same_pages); goto out; } handle = zram_get_handle(zram, index); if (!handle) return; zs_free(zram->mem_pool, handle); atomic64_sub(zram_get_obj_size(zram, index), &zram->stats.compr_data_size); out: atomic64_dec(&zram->stats.pages_stored); zram_set_handle(zram, index, 0); zram_set_obj_size(zram, index, 0); WARN_ON_ONCE(zram->table[index].flags & ~(1UL << ZRAM_LOCK | 1UL << ZRAM_UNDER_WB)); } static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, struct bio *bio, bool partial_io) { struct zcomp_strm *zstrm; unsigned long handle; unsigned int size; void *src, *dst; int ret; zram_slot_lock(zram, index); if (zram_test_flag(zram, index, ZRAM_WB)) { struct bio_vec bvec; zram_slot_unlock(zram, index); bvec.bv_page = page; bvec.bv_len = PAGE_SIZE; bvec.bv_offset = 0; return read_from_bdev(zram, &bvec, zram_get_element(zram, index), bio, partial_io); } handle = zram_get_handle(zram, index); if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) { unsigned long value; void *mem; value = handle ? zram_get_element(zram, index) : 0; mem = kmap_atomic(page); zram_fill_page(mem, PAGE_SIZE, value); kunmap_atomic(mem); zram_slot_unlock(zram, index); return 0; } size = zram_get_obj_size(zram, index); if (size != PAGE_SIZE) zstrm = zcomp_stream_get(zram->comp); src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO); if (size == PAGE_SIZE) { dst = kmap_atomic(page); memcpy(dst, src, PAGE_SIZE); kunmap_atomic(dst); ret = 0; } else { dst = kmap_atomic(page); ret = zcomp_decompress(zstrm, src, size, dst); kunmap_atomic(dst); zcomp_stream_put(zram->comp); } zs_unmap_object(zram->mem_pool, handle); zram_slot_unlock(zram, index); /* Should NEVER happen. Return bio error if it does. */ if (WARN_ON(ret)) pr_err("Decompression failed! err=%d, page=%u\n", ret, index); return ret; } static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, u32 index, int offset, struct bio *bio) { int ret; struct page *page; page = bvec->bv_page; if (is_partial_io(bvec)) { /* Use a temporary buffer to decompress the page */ page = alloc_page(GFP_NOIO|__GFP_HIGHMEM); if (!page) return -ENOMEM; } ret = __zram_bvec_read(zram, page, index, bio, is_partial_io(bvec)); if (unlikely(ret)) goto out; if (is_partial_io(bvec)) { void *src = kmap_atomic(page); memcpy_to_bvec(bvec, src + offset); kunmap_atomic(src); } out: if (is_partial_io(bvec)) __free_page(page); return ret; } static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, struct bio *bio) { int ret = 0; unsigned long alloced_pages; unsigned long handle = 0; unsigned int comp_len = 0; void *src, *dst, *mem; struct zcomp_strm *zstrm; struct page *page = bvec->bv_page; unsigned long element = 0; enum zram_pageflags flags = 0; mem = kmap_atomic(page); if (page_same_filled(mem, &element)) { kunmap_atomic(mem); /* Free memory associated with this sector now. */ flags = ZRAM_SAME; atomic64_inc(&zram->stats.same_pages); goto out; } kunmap_atomic(mem); zstrm = zcomp_stream_get(zram->comp); src = kmap_atomic(page); ret = zcomp_compress(zstrm, src, &comp_len); kunmap_atomic(src); if (unlikely(ret)) { zcomp_stream_put(zram->comp); pr_err("Compression failed! err=%d\n", ret); return ret; } if (comp_len >= huge_class_size) comp_len = PAGE_SIZE; handle = zs_malloc(zram->mem_pool, comp_len, __GFP_KSWAPD_RECLAIM | __GFP_NOWARN | __GFP_HIGHMEM | __GFP_MOVABLE); if (unlikely(!handle)) { zcomp_stream_put(zram->comp); return -ENOMEM; } alloced_pages = zs_get_total_pages(zram->mem_pool); update_used_max(zram, alloced_pages); if (zram->limit_pages && alloced_pages > zram->limit_pages) { zcomp_stream_put(zram->comp); zs_free(zram->mem_pool, handle); return -ENOMEM; } dst = zs_map_object(zram->mem_pool, handle, ZS_MM_WO); src = zstrm->buffer; if (comp_len == PAGE_SIZE) src = kmap_atomic(page); memcpy(dst, src, comp_len); if (comp_len == PAGE_SIZE) kunmap_atomic(src); zcomp_stream_put(zram->comp); zs_unmap_object(zram->mem_pool, handle); atomic64_add(comp_len, &zram->stats.compr_data_size); out: /* * Free memory associated with this sector * before overwriting unused sectors. */ zram_slot_lock(zram, index); zram_free_page(zram, index); if (comp_len == PAGE_SIZE) { zram_set_flag(zram, index, ZRAM_HUGE); atomic64_inc(&zram->stats.huge_pages); atomic64_inc(&zram->stats.huge_pages_since); } if (flags) { zram_set_flag(zram, index, flags); zram_set_element(zram, index, element); } else { zram_set_handle(zram, index, handle); zram_set_obj_size(zram, index, comp_len); } zram_slot_unlock(zram, index); /* Update stats */ atomic64_inc(&zram->stats.pages_stored); return ret; } static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, int offset, struct bio *bio) { int ret; struct page *page = NULL; struct bio_vec vec; vec = *bvec; if (is_partial_io(bvec)) { void *dst; /* * This is a partial IO. We need to read the full page * before to write the changes. */ page = alloc_page(GFP_NOIO|__GFP_HIGHMEM); if (!page) return -ENOMEM; ret = __zram_bvec_read(zram, page, index, bio, true); if (ret) goto out; dst = kmap_atomic(page); memcpy_from_bvec(dst + offset, bvec); kunmap_atomic(dst); vec.bv_page = page; vec.bv_len = PAGE_SIZE; vec.bv_offset = 0; } ret = __zram_bvec_write(zram, &vec, index, bio); out: if (is_partial_io(bvec)) __free_page(page); 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; /* * 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) { zram_slot_lock(zram, index); zram_free_page(zram, index); zram_slot_unlock(zram, index); atomic64_inc(&zram->stats.notify_free); index++; n -= PAGE_SIZE; } } /* * Returns errno if it has some problem. Otherwise return 0 or 1. * Returns 0 if IO request was done synchronously * Returns 1 if IO request was successfully submitted. */ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, int offset, unsigned int op, struct bio *bio) { int ret; if (!op_is_write(op)) { atomic64_inc(&zram->stats.num_reads); ret = zram_bvec_read(zram, bvec, index, offset, bio); flush_dcache_page(bvec->bv_page); } else { atomic64_inc(&zram->stats.num_writes); ret = zram_bvec_write(zram, bvec, index, offset, bio); } zram_slot_lock(zram, index); zram_accessed(zram, index); zram_slot_unlock(zram, index); if (unlikely(ret < 0)) { if (!op_is_write(op)) atomic64_inc(&zram->stats.failed_reads); else atomic64_inc(&zram->stats.failed_writes); } 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; unsigned long start_time; index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT; offset = (bio->bi_iter.bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT; switch (bio_op(bio)) { case REQ_OP_DISCARD: case REQ_OP_WRITE_ZEROES: zram_bio_discard(zram, index, offset, bio); bio_endio(bio); return; default: break; } start_time = bio_start_io_acct(bio); bio_for_each_segment(bvec, bio, iter) { struct bio_vec bv = bvec; unsigned int unwritten = bvec.bv_len; do { bv.bv_len = min_t(unsigned int, PAGE_SIZE - offset, unwritten); if (zram_bvec_rw(zram, &bv, index, offset, bio_op(bio), bio) < 0) { bio->bi_status = BLK_STS_IOERR; break; } bv.bv_offset += bv.bv_len; unwritten -= bv.bv_len; update_position(&index, &offset, &bv); } while (unwritten); } bio_end_io_acct(bio, start_time); bio_endio(bio); } /* * Handler function for all zram I/O requests. */ static void zram_submit_bio(struct bio *bio) { struct zram *zram = bio->bi_bdev->bd_disk->private_data; if (!valid_io_request(zram, bio->bi_iter.bi_sector, bio->bi_iter.bi_size)) { atomic64_inc(&zram->stats.invalid_io); bio_io_error(bio); return; } __zram_make_request(zram, bio); } static void zram_slot_free_notify(struct block_device *bdev, unsigned long index) { struct zram *zram; zram = bdev->bd_disk->private_data; atomic64_inc(&zram->stats.notify_free); if (!zram_slot_trylock(zram, index)) { atomic64_inc(&zram->stats.miss_free); return; } zram_free_page(zram, index); zram_slot_unlock(zram, index); } static int zram_rw_page(struct block_device *bdev, sector_t sector, struct page *page, unsigned int op) { int offset, ret; u32 index; struct zram *zram; struct bio_vec bv; unsigned long start_time; if (PageTransHuge(page)) return -ENOTSUPP; zram = bdev->bd_disk->private_data; if (!valid_io_request(zram, sector, PAGE_SIZE)) { atomic64_inc(&zram->stats.invalid_io); ret = -EINVAL; goto out; } 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; start_time = bdev_start_io_acct(bdev->bd_disk->part0, SECTORS_PER_PAGE, op, jiffies); ret = zram_bvec_rw(zram, &bv, index, offset, op, NULL); bdev_end_io_acct(bdev->bd_disk->part0, op, start_time); 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 (unlikely(ret < 0)) return ret; switch (ret) { case 0: page_endio(page, op_is_write(op), 0); break; case 1: ret = 0; break; default: WARN_ON(1); } return ret; } static void zram_reset_device(struct zram *zram) { struct zcomp *comp; u64 disksize; down_write(&zram->init_lock); zram->limit_pages = 0; if (!init_done(zram)) { up_write(&zram->init_lock); return; } comp = zram->comp; disksize = zram->disksize; zram->disksize = 0; set_capacity_and_notify(zram->disk, 0); part_stat_set_all(zram->disk->part0, 0); /* I/O operation under all of CPU are done so let's free */ zram_meta_free(zram, disksize); memset(&zram->stats, 0, sizeof(zram->stats)); zcomp_destroy(comp); reset_bdev(zram); up_write(&zram->init_lock); } 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 *zram = dev_to_zram(dev); int err; disksize = memparse(buf, NULL); if (!disksize) return -EINVAL; down_write(&zram->init_lock); if (init_done(zram)) { pr_info("Cannot change disksize for initialized device\n"); err = -EBUSY; goto out_unlock; } disksize = PAGE_ALIGN(disksize); if (!zram_meta_alloc(zram, disksize)) { err = -ENOMEM; goto out_unlock; } comp = zcomp_create(zram->compressor); if (IS_ERR(comp)) { pr_err("Cannot initialise %s compressing backend\n", zram->compressor); err = PTR_ERR(comp); goto out_free_meta; } zram->comp = comp; zram->disksize = disksize; set_capacity_and_notify(zram->disk, zram->disksize >> SECTOR_SHIFT); up_write(&zram->init_lock); return len; out_free_meta: zram_meta_free(zram, disksize); out_unlock: up_write(&zram->init_lock); 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 gendisk *disk; ret = kstrtou16(buf, 10, &do_reset); if (ret) return ret; if (!do_reset) return -EINVAL; zram = dev_to_zram(dev); disk = zram->disk; mutex_lock(&disk->open_mutex); /* Do not reset an active device or claimed device */ if (disk_openers(disk) || zram->claim) { mutex_unlock(&disk->open_mutex); return -EBUSY; } /* From now on, anyone can't open /dev/zram[0-9] */ zram->claim = true; mutex_unlock(&disk->open_mutex); /* Make sure all the pending I/O are finished */ sync_blockdev(disk->part0); zram_reset_device(zram); mutex_lock(&disk->open_mutex); zram->claim = false; mutex_unlock(&disk->open_mutex); return len; } static int zram_open(struct block_device *bdev, fmode_t mode) { int ret = 0; struct zram *zram; WARN_ON(!mutex_is_locked(&bdev->bd_disk->open_mutex)); zram = bdev->bd_disk->private_data; /* zram was claimed to reset so open request fails */ if (zram->claim) ret = -EBUSY; return ret; } static const struct block_device_operations zram_devops = { .open = zram_open, .submit_bio = zram_submit_bio, .swap_slot_free_notify = zram_slot_free_notify, .rw_page = zram_rw_page, .owner = THIS_MODULE }; #ifdef CONFIG_ZRAM_WRITEBACK static const struct block_device_operations zram_wb_devops = { .open = zram_open, .submit_bio = zram_submit_bio, .swap_slot_free_notify = zram_slot_free_notify, .owner = THIS_MODULE }; #endif static DEVICE_ATTR_WO(compact); static DEVICE_ATTR_RW(disksize); static DEVICE_ATTR_RO(initstate); static DEVICE_ATTR_WO(reset); static DEVICE_ATTR_WO(mem_limit); static DEVICE_ATTR_WO(mem_used_max); static DEVICE_ATTR_WO(idle); static DEVICE_ATTR_RW(max_comp_streams); static DEVICE_ATTR_RW(comp_algorithm); #ifdef CONFIG_ZRAM_WRITEBACK static DEVICE_ATTR_RW(backing_dev); static DEVICE_ATTR_WO(writeback); static DEVICE_ATTR_RW(writeback_limit); static DEVICE_ATTR_RW(writeback_limit_enable); #endif static struct attribute *zram_disk_attrs[] = { &dev_attr_disksize.attr, &dev_attr_initstate.attr, &dev_attr_reset.attr, &dev_attr_compact.attr, &dev_attr_mem_limit.attr, &dev_attr_mem_used_max.attr, &dev_attr_idle.attr, &dev_attr_max_comp_streams.attr, &dev_attr_comp_algorithm.attr, #ifdef CONFIG_ZRAM_WRITEBACK &dev_attr_backing_dev.attr, &dev_attr_writeback.attr, &dev_attr_writeback_limit.attr, &dev_attr_writeback_limit_enable.attr, #endif &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, #ifdef CONFIG_ZRAM_WRITEBACK &dev_attr_bd_stat.attr, #endif &dev_attr_debug_stat.attr, NULL, }; ATTRIBUTE_GROUPS(zram_disk); /* * Allocate and initialize new zram device. the function returns * '>= 0' device_id upon success, and negative value otherwise. */ static int zram_add(void) { struct zram *zram; int ret, device_id; zram = kzalloc(sizeof(struct zram), GFP_KERNEL); if (!zram) return -ENOMEM; ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL); if (ret < 0) goto out_free_dev; device_id = ret; init_rwsem(&zram->init_lock); #ifdef CONFIG_ZRAM_WRITEBACK spin_lock_init(&zram->wb_limit_lock); #endif /* gendisk structure */ zram->disk = blk_alloc_disk(NUMA_NO_NODE); if (!zram->disk) { pr_err("Error allocating disk structure for device %d\n", device_id); ret = -ENOMEM; goto out_free_idr; } zram->disk->major = zram_major; zram->disk->first_minor = device_id; zram->disk->minors = 1; zram->disk->flags |= GENHD_FL_NO_PART; zram->disk->fops = &zram_devops; 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 */ blk_queue_flag_set(QUEUE_FLAG_NONROT, zram->disk->queue); blk_queue_flag_clear(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; blk_queue_max_discard_sectors(zram->disk->queue, 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) blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX); ret = device_add_disk(NULL, zram->disk, zram_disk_groups); if (ret) goto out_cleanup_disk; strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor)); zram_debugfs_register(zram); pr_info("Added device: %s\n", zram->disk->disk_name); return device_id; out_cleanup_disk: put_disk(zram->disk); out_free_idr: idr_remove(&zram_index_idr, device_id); out_free_dev: kfree(zram); return ret; } static int zram_remove(struct zram *zram) { bool claimed; mutex_lock(&zram->disk->open_mutex); if (disk_openers(zram->disk)) { mutex_unlock(&zram->disk->open_mutex); return -EBUSY; } claimed = zram->claim; if (!claimed) zram->claim = true; mutex_unlock(&zram->disk->open_mutex); zram_debugfs_unregister(zram); if (claimed) { /* * If we were claimed by reset_store(), del_gendisk() will * wait until reset_store() is done, so nothing need to do. */ ; } else { /* Make sure all the pending I/O are finished */ sync_blockdev(zram->disk->part0); zram_reset_device(zram); } pr_info("Removed device: %s\n", zram->disk->disk_name); del_gendisk(zram->disk); /* del_gendisk drains pending reset_store */ WARN_ON_ONCE(claimed && zram->claim); /* * disksize_store() may be called in between zram_reset_device() * and del_gendisk(), so run the last reset to avoid leaking * anything allocated with disksize_store() */ zram_reset_device(zram); put_disk(zram->disk); kfree(zram); return 0; } /* zram-control sysfs attributes */ /* * NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a * sense that reading from this file does alter the state of your system -- it * creates a new un-initialized zram device and returns back this device's * device_id (or an error code if it fails to create a new device). */ static ssize_t hot_add_show(struct class *class, struct class_attribute *attr, char *buf) { int ret; mutex_lock(&zram_index_mutex); ret = zram_add(); mutex_unlock(&zram_index_mutex); if (ret < 0) return ret; return scnprintf(buf, PAGE_SIZE, "%d\n", ret); } static struct class_attribute class_attr_hot_add = __ATTR(hot_add, 0400, hot_add_show, NULL); static ssize_t hot_remove_store(struct class *class, struct class_attribute *attr, const char *buf, size_t count) { struct zram *zram; int ret, dev_id; /* dev_id is gendisk->first_minor, which is `int' */ ret = kstrtoint(buf, 10, &dev_id); if (ret) return ret; if (dev_id < 0) return -EINVAL; mutex_lock(&zram_index_mutex); zram = idr_find(&zram_index_idr, dev_id); if (zram) { ret = zram_remove(zram); if (!ret) idr_remove(&zram_index_idr, dev_id); } else { ret = -ENODEV; } mutex_unlock(&zram_index_mutex); return ret ? ret : count; } static CLASS_ATTR_WO(hot_remove); static struct attribute *zram_control_class_attrs[] = { &class_attr_hot_add.attr, &class_attr_hot_remove.attr, NULL, }; ATTRIBUTE_GROUPS(zram_control_class); static struct class zram_control_class = { .name = "zram-control", .owner = THIS_MODULE, .class_groups = zram_control_class_groups, }; static int zram_remove_cb(int id, void *ptr, void *data) { WARN_ON_ONCE(zram_remove(ptr)); return 0; } static void destroy_devices(void) { class_unregister(&zram_control_class); idr_for_each(&zram_index_idr, &zram_remove_cb, NULL); zram_debugfs_destroy(); idr_destroy(&zram_index_idr); unregister_blkdev(zram_major, "zram"); cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE); } static int __init zram_init(void) { int ret; ret = cpuhp_setup_state_multi(CPUHP_ZCOMP_PREPARE, "block/zram:prepare", zcomp_cpu_up_prepare, zcomp_cpu_dead); if (ret < 0) return ret; ret = class_register(&zram_control_class); if (ret) { pr_err("Unable to register zram-control class\n"); cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE); return ret; } zram_debugfs_create(); zram_major = register_blkdev(0, "zram"); if (zram_major <= 0) { pr_err("Unable to get major number\n"); class_unregister(&zram_control_class); cpuhp_remove_multi_state(CPUHP_ZCOMP_PREPARE); return -EBUSY; } while (num_devices != 0) { mutex_lock(&zram_index_mutex); ret = zram_add(); mutex_unlock(&zram_index_mutex); if (ret < 0) goto out_error; num_devices--; } return 0; out_error: destroy_devices(); return ret; } static void __exit zram_exit(void) { destroy_devices(); } module_init(zram_init); module_exit(zram_exit); module_param(num_devices, uint, 0); MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices"); MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Nitin Gupta "); MODULE_DESCRIPTION("Compressed RAM Block Device");