diff options
Diffstat (limited to 'drivers/block/zram/zram_drv.c')
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 1922 |
1 files changed, 1922 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..5e05bfcec --- /dev/null +++ b/drivers/block/zram/zram_drv.c @@ -0,0 +1,1922 @@ +/* + * 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 <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/backing-dev.h> +#include <linux/string.h> +#include <linux/vmalloc.h> +#include <linux/err.h> +#include <linux/idr.h> +#include <linux/sysfs.h> +#include <linux/debugfs.h> +#include <linux/cpuhotplug.h> + +#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 = "lzo"; + +/* 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 void zram_free_page(struct zram *zram, size_t index); + +static int zram_slot_trylock(struct zram *zram, u32 index) +{ + return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].value); +} + +static void zram_slot_lock(struct zram *zram, u32 index) +{ + bit_spin_lock(ZRAM_LOCK, &zram->table[index].value); +} + +static void zram_slot_unlock(struct zram *zram, u32 index) +{ + bit_spin_unlock(ZRAM_LOCK, &zram->table[index].value); +} + +static inline bool init_done(struct zram *zram) +{ + return zram->disksize; +} + +static inline bool zram_allocated(struct zram *zram, u32 index) +{ + + return (zram->table[index].value >> (ZRAM_FLAG_SHIFT + 1)) || + zram->table[index].handle; +} + +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].value & BIT(flag); +} + +static void zram_set_flag(struct zram *zram, u32 index, + enum zram_pageflags flag) +{ + zram->table[index].value |= BIT(flag); +} + +static void zram_clear_flag(struct zram *zram, u32 index, + enum zram_pageflags flag) +{ + zram->table[index].value &= ~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].value & (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].value >> ZRAM_FLAG_SHIFT; + + zram->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size; +} + +#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 int pos; + unsigned long *page; + unsigned long val; + + page = (unsigned long *)ptr; + val = page[0]; + + for (pos = 1; pos < PAGE_SIZE / sizeof(*page); 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; +} + +#ifdef CONFIG_ZRAM_WRITEBACK +static bool zram_wb_enabled(struct zram *zram) +{ + return zram->backing_dev; +} + +static void reset_bdev(struct zram *zram) +{ + struct block_device *bdev; + + if (!zram_wb_enabled(zram)) + return; + + bdev = zram->bdev; + if (zram->old_block_size) + set_blocksize(bdev, zram->old_block_size); + 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->old_block_size = 0; + zram->bdev = NULL; + zram->disk->queue->backing_dev_info->capabilities |= + BDI_CAP_SYNCHRONOUS_IO; + 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, old_block_size = 0; + 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 = bdgrab(I_BDEV(inode)); + err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram); + if (err < 0) { + 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; + } + + old_block_size = block_size(bdev); + err = set_blocksize(bdev, PAGE_SIZE); + if (err) + goto out; + + reset_bdev(zram); + + zram->old_block_size = old_block_size; + 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->queue->backing_dev_info->capabilities &= + ~BDI_CAP_SYNCHRONOUS_IO; + up_write(&zram->init_lock); + + pr_info("setup backing device %s\n", file_name); + kfree(file_name); + + return len; +out: + if (bitmap) + 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 get_entry_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; + + return blk_idx; +} + +static void put_entry_bdev(struct zram *zram, unsigned long entry) +{ + int was_set; + + was_set = test_and_clear_bit(entry, zram->bitmap); + WARN_ON_ONCE(!was_set); +} + +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(GFP_ATOMIC, 1); + if (!bio) + return -ENOMEM; + + bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9); + bio_set_dev(bio, zram->bdev); + if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, bvec->bv_offset)) { + bio_put(bio); + return -EIO; + } + + if (!parent) { + bio->bi_opf = REQ_OP_READ; + bio->bi_end_io = zram_page_end_io; + } else { + bio->bi_opf = parent->bi_opf; + bio_chain(bio, parent); + } + + submit_bio(bio); + return 1; +} + +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 ->make_request_fn to be active at a time + * so if we use chained IO with parent IO in same context, + * it's a deadlock. To avoid, it, it uses 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) +{ + if (sync) + return read_from_bdev_sync(zram, bvec, entry, parent); + else + return read_from_bdev_async(zram, bvec, entry, parent); +} + +static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, + u32 index, struct bio *parent, + unsigned long *pentry) +{ + struct bio *bio; + unsigned long entry; + + bio = bio_alloc(GFP_ATOMIC, 1); + if (!bio) + return -ENOMEM; + + entry = get_entry_bdev(zram); + if (!entry) { + bio_put(bio); + return -ENOSPC; + } + + bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9); + bio_set_dev(bio, zram->bdev); + if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, + bvec->bv_offset)) { + bio_put(bio); + put_entry_bdev(zram, entry); + return -EIO; + } + + if (!parent) { + bio->bi_opf = REQ_OP_WRITE | REQ_SYNC; + bio->bi_end_io = zram_page_end_io; + } else { + bio->bi_opf = parent->bi_opf; + bio_chain(bio, parent); + } + + submit_bio(bio); + *pentry = entry; + + return 0; +} + +static void zram_wb_clear(struct zram *zram, u32 index) +{ + unsigned long entry; + + zram_clear_flag(zram, index, ZRAM_WB); + entry = zram_get_element(zram, index); + zram_set_element(zram, index, 0); + put_entry_bdev(zram, entry); +} + +#else +static bool zram_wb_enabled(struct zram *zram) { return false; } +static inline void reset_bdev(struct zram *zram) {}; +static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, + u32 index, struct bio *parent, + unsigned long *pentry) + +{ + return -EIO; +} + +static int read_from_bdev(struct zram *zram, struct bio_vec *bvec, + unsigned long entry, struct bio *parent, bool sync) +{ + return -EIO; +} +static void zram_wb_clear(struct zram *zram, u32 index) {} +#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->table[index].ac_time = ktime_get_boottime(); +} + +static void zram_reset_access(struct zram *zram, u32 index) +{ + zram->table[index].ac_time = 0; +} + +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\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' : '.'); + + 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) {}; +static void zram_reset_access(struct zram *zram, u32 index) {}; +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\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)); + up_read(&zram->init_lock); + + return ret; +} + +static ssize_t debug_stat_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + int version = 1; + struct zram *zram = dev_to_zram(dev); + ssize_t ret; + + down_read(&zram->init_lock); + ret = scnprintf(buf, PAGE_SIZE, + "version: %d\n%8llu %8llu\n", + version, + (u64)atomic64_read(&zram->stats.writestall), + (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); +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; + + zram_reset_access(zram, index); + + if (zram_test_flag(zram, index, ZRAM_HUGE)) { + zram_clear_flag(zram, index, ZRAM_HUGE); + atomic64_dec(&zram->stats.huge_pages); + } + + if (zram_wb_enabled(zram) && zram_test_flag(zram, index, ZRAM_WB)) { + zram_wb_clear(zram, index); + atomic64_dec(&zram->stats.pages_stored); + return; + } + + /* + * 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); + zram_set_element(zram, index, 0); + atomic64_dec(&zram->stats.same_pages); + atomic64_dec(&zram->stats.pages_stored); + return; + } + + 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); + atomic64_dec(&zram->stats.pages_stored); + + zram_set_handle(zram, index, 0); + zram_set_obj_size(zram, index, 0); +} + +static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, + struct bio *bio, bool partial_io) +{ + int ret; + unsigned long handle; + unsigned int size; + void *src, *dst; + + if (zram_wb_enabled(zram)) { + 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); + } + zram_slot_unlock(zram, index); + } + + zram_slot_lock(zram, index); + 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); + + 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 { + struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp); + + 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 (unlikely(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 *dst = kmap_atomic(bvec->bv_page); + void *src = kmap_atomic(page); + + memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len); + kunmap_atomic(src); + kunmap_atomic(dst); + } +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; + bool allow_wb = true; + + 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); + +compress_again: + 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); + zs_free(zram->mem_pool, handle); + return ret; + } + + if (unlikely(comp_len >= huge_class_size)) { + comp_len = PAGE_SIZE; + if (zram_wb_enabled(zram) && allow_wb) { + zcomp_stream_put(zram->comp); + ret = write_to_bdev(zram, bvec, index, bio, &element); + if (!ret) { + flags = ZRAM_WB; + ret = 1; + goto out; + } + allow_wb = false; + goto compress_again; + } + } + + /* + * handle allocation has 2 paths: + * a) fast path is executed with preemption disabled (for + * per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear, + * since we can't sleep; + * b) slow path enables preemption and attempts to allocate + * the page with __GFP_DIRECT_RECLAIM bit set. we have to + * put per-cpu compression stream and, thus, to re-do + * the compression once handle is allocated. + * + * if we have a 'non-null' handle here then we are coming + * from the slow path and handle has already been allocated. + */ + if (!handle) + handle = zs_malloc(zram->mem_pool, comp_len, + __GFP_KSWAPD_RECLAIM | + __GFP_NOWARN | + __GFP_HIGHMEM | + __GFP_MOVABLE); + if (!handle) { + zcomp_stream_put(zram->comp); + atomic64_inc(&zram->stats.writestall); + handle = zs_malloc(zram->mem_pool, comp_len, + GFP_NOIO | __GFP_HIGHMEM | + __GFP_MOVABLE); + if (handle) + goto compress_again; + 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); + } + + 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; + void *src; + 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; + + src = kmap_atomic(bvec->bv_page); + dst = kmap_atomic(page); + memcpy(dst + offset, src + bvec->bv_offset, bvec->bv_len); + kunmap_atomic(dst); + kunmap_atomic(src); + + 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) +{ + unsigned long start_time = jiffies; + struct request_queue *q = zram->disk->queue; + int ret; + + generic_start_io_acct(q, op, bvec->bv_len >> SECTOR_SHIFT, + &zram->disk->part0); + + 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); + } + + generic_end_io_acct(q, op, &zram->disk->part0, start_time); + + 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; + + 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; + } + + 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) + goto out; + + bv.bv_offset += bv.bv_len; + unwritten -= bv.bv_len; + + update_position(&index, &offset, &bv); + } while (unwritten); + } + + bio_endio(bio); + return; + +out: + bio_io_error(bio); +} + +/* + * Handler function for all zram I/O requests. + */ +static blk_qc_t zram_make_request(struct request_queue *queue, struct bio *bio) +{ + struct zram *zram = queue->queuedata; + + if (!valid_io_request(zram, bio->bi_iter.bi_sector, + bio->bi_iter.bi_size)) { + atomic64_inc(&zram->stats.invalid_io); + goto error; + } + + __zram_make_request(zram, bio); + return BLK_QC_T_NONE; + +error: + bio_io_error(bio); + return BLK_QC_T_NONE; +} + +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; + + 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; + + ret = zram_bvec_rw(zram, &bv, index, offset, op, NULL); +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(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(zram, disksize); + memset(&zram->stats, 0, sizeof(zram->stats)); + zcomp_destroy(comp); + reset_bdev(zram); +} + +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(zram->disk, zram->disksize >> SECTOR_SHIFT); + + revalidate_disk(zram->disk); + 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 block_device *bdev; + + ret = kstrtou16(buf, 10, &do_reset); + if (ret) + return ret; + + if (!do_reset) + return -EINVAL; + + 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 or claimed device */ + if (bdev->bd_openers || zram->claim) { + mutex_unlock(&bdev->bd_mutex); + bdput(bdev); + return -EBUSY; + } + + /* From now on, anyone can't open /dev/zram[0-9] */ + zram->claim = true; + mutex_unlock(&bdev->bd_mutex); + + /* Make sure all the pending I/O are finished */ + fsync_bdev(bdev); + zram_reset_device(zram); + revalidate_disk(zram->disk); + bdput(bdev); + + mutex_lock(&bdev->bd_mutex); + zram->claim = false; + mutex_unlock(&bdev->bd_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_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, + .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_WO(mem_limit); +static DEVICE_ATTR_WO(mem_used_max); +static DEVICE_ATTR_RW(max_comp_streams); +static DEVICE_ATTR_RW(comp_algorithm); +#ifdef CONFIG_ZRAM_WRITEBACK +static DEVICE_ATTR_RW(backing_dev); +#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_max_comp_streams.attr, + &dev_attr_comp_algorithm.attr, +#ifdef CONFIG_ZRAM_WRITEBACK + &dev_attr_backing_dev.attr, +#endif + &dev_attr_io_stat.attr, + &dev_attr_mm_stat.attr, + &dev_attr_debug_stat.attr, + NULL, +}; + +static const struct attribute_group zram_disk_attr_group = { + .attrs = zram_disk_attrs, +}; + +static const struct attribute_group *zram_disk_attr_groups[] = { + &zram_disk_attr_group, + NULL, +}; + +/* + * 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; + struct request_queue *queue; + 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); + + queue = blk_alloc_queue(GFP_KERNEL); + if (!queue) { + pr_err("Error allocating disk queue for device %d\n", + device_id); + ret = -ENOMEM; + goto out_free_idr; + } + + blk_queue_make_request(queue, zram_make_request); + + /* gendisk structure */ + zram->disk = alloc_disk(1); + if (!zram->disk) { + pr_err("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 */ + 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); + blk_queue_flag_set(QUEUE_FLAG_DISCARD, zram->disk->queue); + + /* + * 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); + + zram->disk->queue->backing_dev_info->capabilities |= + (BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO); + device_add_disk(NULL, zram->disk, zram_disk_attr_groups); + + 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_free_queue: + blk_cleanup_queue(queue); +out_free_idr: + idr_remove(&zram_index_idr, device_id); +out_free_dev: + kfree(zram); + return ret; +} + +static int zram_remove(struct zram *zram) +{ + struct block_device *bdev; + + bdev = bdget_disk(zram->disk, 0); + if (!bdev) + return -ENOMEM; + + mutex_lock(&bdev->bd_mutex); + if (bdev->bd_openers || zram->claim) { + mutex_unlock(&bdev->bd_mutex); + bdput(bdev); + return -EBUSY; + } + + zram->claim = true; + mutex_unlock(&bdev->bd_mutex); + + zram_debugfs_unregister(zram); + + /* Make sure all the pending I/O are finished */ + fsync_bdev(bdev); + zram_reset_device(zram); + bdput(bdev); + + pr_info("Removed device: %s\n", zram->disk->disk_name); + + del_gendisk(zram->disk); + blk_cleanup_queue(zram->disk->queue); + 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) +{ + 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 <ngupta@vflare.org>"); +MODULE_DESCRIPTION("Compressed RAM Block Device"); |