linux/drivers/block/zram/zram_drv.c

959 lines
22 KiB
C

/*
* Compressed RAM block device
*
* Copyright (C) 2008, 2009, 2010 Nitin Gupta
* 2012, 2013 Minchan Kim
*
* This code is released using a dual license strategy: BSD/GPL
* You can choose the licence that better fits your requirements.
*
* Released under the terms of 3-clause BSD License
* Released under the terms of GNU General Public License Version 2.0
*
*/
#define KMSG_COMPONENT "zram"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#ifdef CONFIG_ZRAM_DEBUG
#define DEBUG
#endif
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/bio.h>
#include <linux/bitops.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/device.h>
#include <linux/genhd.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/lzo.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include "zram_drv.h"
/* Globals */
static int zram_major;
static struct zram *zram_devices;
/* Module params (documentation at end) */
static unsigned int num_devices = 1;
static inline struct zram *dev_to_zram(struct device *dev)
{
return (struct zram *)dev_to_disk(dev)->private_data;
}
static ssize_t disksize_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%llu\n", zram->disksize);
}
static ssize_t initstate_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%u\n", zram->init_done);
}
static ssize_t num_reads_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%llu\n",
(u64)atomic64_read(&zram->stats.num_reads));
}
static ssize_t num_writes_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%llu\n",
(u64)atomic64_read(&zram->stats.num_writes));
}
static ssize_t invalid_io_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%llu\n",
(u64)atomic64_read(&zram->stats.invalid_io));
}
static ssize_t notify_free_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%llu\n",
(u64)atomic64_read(&zram->stats.notify_free));
}
static ssize_t zero_pages_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%u\n", atomic_read(&zram->stats.pages_zero));
}
static ssize_t orig_data_size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%llu\n",
(u64)(atomic_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
}
static ssize_t compr_data_size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct zram *zram = dev_to_zram(dev);
return sprintf(buf, "%llu\n",
(u64)atomic64_read(&zram->stats.compr_size));
}
static ssize_t mem_used_total_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
u64 val = 0;
struct zram *zram = dev_to_zram(dev);
struct zram_meta *meta = zram->meta;
down_read(&zram->init_lock);
if (zram->init_done)
val = zs_get_total_size_bytes(meta->mem_pool);
up_read(&zram->init_lock);
return sprintf(buf, "%llu\n", val);
}
/* flag operations needs meta->tb_lock */
static int zram_test_flag(struct zram_meta *meta, u32 index,
enum zram_pageflags flag)
{
return meta->table[index].flags & BIT(flag);
}
static void zram_set_flag(struct zram_meta *meta, u32 index,
enum zram_pageflags flag)
{
meta->table[index].flags |= BIT(flag);
}
static void zram_clear_flag(struct zram_meta *meta, u32 index,
enum zram_pageflags flag)
{
meta->table[index].flags &= ~BIT(flag);
}
static inline int is_partial_io(struct bio_vec *bvec)
{
return bvec->bv_len != PAGE_SIZE;
}
/*
* Check if request is within bounds and aligned on zram logical blocks.
*/
static inline int valid_io_request(struct zram *zram, struct bio *bio)
{
u64 start, end, bound;
/* unaligned request */
if (unlikely(bio->bi_iter.bi_sector &
(ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
return 0;
if (unlikely(bio->bi_iter.bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
return 0;
start = bio->bi_iter.bi_sector;
end = start + (bio->bi_iter.bi_size >> SECTOR_SHIFT);
bound = zram->disksize >> SECTOR_SHIFT;
/* out of range range */
if (unlikely(start >= bound || end > bound || start > end))
return 0;
/* I/O request is valid */
return 1;
}
static void zram_meta_free(struct zram_meta *meta)
{
zs_destroy_pool(meta->mem_pool);
kfree(meta->compress_workmem);
free_pages((unsigned long)meta->compress_buffer, 1);
vfree(meta->table);
kfree(meta);
}
static struct zram_meta *zram_meta_alloc(u64 disksize)
{
size_t num_pages;
struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
if (!meta)
goto out;
meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
if (!meta->compress_workmem)
goto free_meta;
meta->compress_buffer =
(void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
if (!meta->compress_buffer) {
pr_err("Error allocating compressor buffer space\n");
goto free_workmem;
}
num_pages = disksize >> PAGE_SHIFT;
meta->table = vzalloc(num_pages * sizeof(*meta->table));
if (!meta->table) {
pr_err("Error allocating zram address table\n");
goto free_buffer;
}
meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
if (!meta->mem_pool) {
pr_err("Error creating memory pool\n");
goto free_table;
}
rwlock_init(&meta->tb_lock);
mutex_init(&meta->buffer_lock);
return meta;
free_table:
vfree(meta->table);
free_buffer:
free_pages((unsigned long)meta->compress_buffer, 1);
free_workmem:
kfree(meta->compress_workmem);
free_meta:
kfree(meta);
meta = NULL;
out:
return meta;
}
static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
{
if (*offset + bvec->bv_len >= PAGE_SIZE)
(*index)++;
*offset = (*offset + bvec->bv_len) % PAGE_SIZE;
}
static int page_zero_filled(void *ptr)
{
unsigned int pos;
unsigned long *page;
page = (unsigned long *)ptr;
for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
if (page[pos])
return 0;
}
return 1;
}
static void handle_zero_page(struct bio_vec *bvec)
{
struct page *page = bvec->bv_page;
void *user_mem;
user_mem = kmap_atomic(page);
if (is_partial_io(bvec))
memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
else
clear_page(user_mem);
kunmap_atomic(user_mem);
flush_dcache_page(page);
}
/* NOTE: caller should hold meta->tb_lock with write-side */
static void zram_free_page(struct zram *zram, size_t index)
{
struct zram_meta *meta = zram->meta;
unsigned long handle = meta->table[index].handle;
u16 size = meta->table[index].size;
if (unlikely(!handle)) {
/*
* No memory is allocated for zero filled pages.
* Simply clear zero page flag.
*/
if (zram_test_flag(meta, index, ZRAM_ZERO)) {
zram_clear_flag(meta, index, ZRAM_ZERO);
atomic_dec(&zram->stats.pages_zero);
}
return;
}
if (unlikely(size > max_zpage_size))
atomic_dec(&zram->stats.bad_compress);
zs_free(meta->mem_pool, handle);
if (size <= PAGE_SIZE / 2)
atomic_dec(&zram->stats.good_compress);
atomic64_sub(meta->table[index].size, &zram->stats.compr_size);
atomic_dec(&zram->stats.pages_stored);
meta->table[index].handle = 0;
meta->table[index].size = 0;
}
static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
{
int ret = LZO_E_OK;
size_t clen = PAGE_SIZE;
unsigned char *cmem;
struct zram_meta *meta = zram->meta;
unsigned long handle;
u16 size;
read_lock(&meta->tb_lock);
handle = meta->table[index].handle;
size = meta->table[index].size;
if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
read_unlock(&meta->tb_lock);
clear_page(mem);
return 0;
}
cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
if (size == PAGE_SIZE)
copy_page(mem, cmem);
else
ret = lzo1x_decompress_safe(cmem, size, mem, &clen);
zs_unmap_object(meta->mem_pool, handle);
read_unlock(&meta->tb_lock);
/* Should NEVER happen. Return bio error if it does. */
if (unlikely(ret != LZO_E_OK)) {
pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
atomic64_inc(&zram->stats.failed_reads);
return ret;
}
return 0;
}
static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
u32 index, int offset, struct bio *bio)
{
int ret;
struct page *page;
unsigned char *user_mem, *uncmem = NULL;
struct zram_meta *meta = zram->meta;
page = bvec->bv_page;
read_lock(&meta->tb_lock);
if (unlikely(!meta->table[index].handle) ||
zram_test_flag(meta, index, ZRAM_ZERO)) {
read_unlock(&meta->tb_lock);
handle_zero_page(bvec);
return 0;
}
read_unlock(&meta->tb_lock);
if (is_partial_io(bvec))
/* Use a temporary buffer to decompress the page */
uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
user_mem = kmap_atomic(page);
if (!is_partial_io(bvec))
uncmem = user_mem;
if (!uncmem) {
pr_info("Unable to allocate temp memory\n");
ret = -ENOMEM;
goto out_cleanup;
}
ret = zram_decompress_page(zram, uncmem, index);
/* Should NEVER happen. Return bio error if it does. */
if (unlikely(ret != LZO_E_OK))
goto out_cleanup;
if (is_partial_io(bvec))
memcpy(user_mem + bvec->bv_offset, uncmem + offset,
bvec->bv_len);
flush_dcache_page(page);
ret = 0;
out_cleanup:
kunmap_atomic(user_mem);
if (is_partial_io(bvec))
kfree(uncmem);
return ret;
}
static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
int offset)
{
int ret = 0;
size_t clen;
unsigned long handle;
struct page *page;
unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
struct zram_meta *meta = zram->meta;
bool locked = false;
page = bvec->bv_page;
src = meta->compress_buffer;
if (is_partial_io(bvec)) {
/*
* This is a partial IO. We need to read the full page
* before to write the changes.
*/
uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
if (!uncmem) {
ret = -ENOMEM;
goto out;
}
ret = zram_decompress_page(zram, uncmem, index);
if (ret)
goto out;
}
mutex_lock(&meta->buffer_lock);
locked = true;
user_mem = kmap_atomic(page);
if (is_partial_io(bvec)) {
memcpy(uncmem + offset, user_mem + bvec->bv_offset,
bvec->bv_len);
kunmap_atomic(user_mem);
user_mem = NULL;
} else {
uncmem = user_mem;
}
if (page_zero_filled(uncmem)) {
kunmap_atomic(user_mem);
/* Free memory associated with this sector now. */
write_lock(&zram->meta->tb_lock);
zram_free_page(zram, index);
zram_set_flag(meta, index, ZRAM_ZERO);
write_unlock(&zram->meta->tb_lock);
atomic_inc(&zram->stats.pages_zero);
ret = 0;
goto out;
}
ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
meta->compress_workmem);
if (!is_partial_io(bvec)) {
kunmap_atomic(user_mem);
user_mem = NULL;
uncmem = NULL;
}
if (unlikely(ret != LZO_E_OK)) {
pr_err("Compression failed! err=%d\n", ret);
goto out;
}
if (unlikely(clen > max_zpage_size)) {
atomic_inc(&zram->stats.bad_compress);
clen = PAGE_SIZE;
src = NULL;
if (is_partial_io(bvec))
src = uncmem;
}
handle = zs_malloc(meta->mem_pool, clen);
if (!handle) {
pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
index, clen);
ret = -ENOMEM;
goto out;
}
cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
src = kmap_atomic(page);
copy_page(cmem, src);
kunmap_atomic(src);
} else {
memcpy(cmem, src, clen);
}
zs_unmap_object(meta->mem_pool, handle);
/*
* Free memory associated with this sector
* before overwriting unused sectors.
*/
write_lock(&zram->meta->tb_lock);
zram_free_page(zram, index);
meta->table[index].handle = handle;
meta->table[index].size = clen;
write_unlock(&zram->meta->tb_lock);
/* Update stats */
atomic64_add(clen, &zram->stats.compr_size);
atomic_inc(&zram->stats.pages_stored);
if (clen <= PAGE_SIZE / 2)
atomic_inc(&zram->stats.good_compress);
out:
if (locked)
mutex_unlock(&meta->buffer_lock);
if (is_partial_io(bvec))
kfree(uncmem);
if (ret)
atomic64_inc(&zram->stats.failed_writes);
return ret;
}
static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
int offset, struct bio *bio, int rw)
{
int ret;
if (rw == READ)
ret = zram_bvec_read(zram, bvec, index, offset, bio);
else
ret = zram_bvec_write(zram, bvec, index, offset);
return ret;
}
static void zram_reset_device(struct zram *zram, bool reset_capacity)
{
size_t index;
struct zram_meta *meta;
down_write(&zram->init_lock);
if (!zram->init_done) {
up_write(&zram->init_lock);
return;
}
meta = zram->meta;
zram->init_done = 0;
/* Free all pages that are still in this zram device */
for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
unsigned long handle = meta->table[index].handle;
if (!handle)
continue;
zs_free(meta->mem_pool, handle);
}
zram_meta_free(zram->meta);
zram->meta = NULL;
/* Reset stats */
memset(&zram->stats, 0, sizeof(zram->stats));
zram->disksize = 0;
if (reset_capacity)
set_capacity(zram->disk, 0);
up_write(&zram->init_lock);
}
static void zram_init_device(struct zram *zram, struct zram_meta *meta)
{
if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
pr_info(
"There is little point creating a zram of greater than "
"twice the size of memory since we expect a 2:1 compression "
"ratio. Note that zram uses about 0.1%% of the size of "
"the disk when not in use so a huge zram is "
"wasteful.\n"
"\tMemory Size: %lu kB\n"
"\tSize you selected: %llu kB\n"
"Continuing anyway ...\n",
(totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
);
}
/* zram devices sort of resembles non-rotational disks */
queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
zram->meta = meta;
zram->init_done = 1;
pr_debug("Initialization done!\n");
}
static ssize_t disksize_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
u64 disksize;
struct zram_meta *meta;
struct zram *zram = dev_to_zram(dev);
disksize = memparse(buf, NULL);
if (!disksize)
return -EINVAL;
disksize = PAGE_ALIGN(disksize);
meta = zram_meta_alloc(disksize);
down_write(&zram->init_lock);
if (zram->init_done) {
up_write(&zram->init_lock);
zram_meta_free(meta);
pr_info("Cannot change disksize for initialized device\n");
return -EBUSY;
}
zram->disksize = disksize;
set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
zram_init_device(zram, meta);
up_write(&zram->init_lock);
return len;
}
static ssize_t reset_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
int ret;
unsigned short do_reset;
struct zram *zram;
struct block_device *bdev;
zram = dev_to_zram(dev);
bdev = bdget_disk(zram->disk, 0);
if (!bdev)
return -ENOMEM;
/* Do not reset an active device! */
if (bdev->bd_holders) {
ret = -EBUSY;
goto out;
}
ret = kstrtou16(buf, 10, &do_reset);
if (ret)
goto out;
if (!do_reset) {
ret = -EINVAL;
goto out;
}
/* Make sure all pending I/O is finished */
fsync_bdev(bdev);
bdput(bdev);
zram_reset_device(zram, true);
return len;
out:
bdput(bdev);
return ret;
}
static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
{
int offset;
u32 index;
struct bio_vec bvec;
struct bvec_iter iter;
switch (rw) {
case READ:
atomic64_inc(&zram->stats.num_reads);
break;
case WRITE:
atomic64_inc(&zram->stats.num_writes);
break;
}
index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
offset = (bio->bi_iter.bi_sector &
(SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
bio_for_each_segment(bvec, bio, iter) {
int max_transfer_size = PAGE_SIZE - offset;
if (bvec.bv_len > max_transfer_size) {
/*
* zram_bvec_rw() can only make operation on a single
* zram page. Split the bio vector.
*/
struct bio_vec bv;
bv.bv_page = bvec.bv_page;
bv.bv_len = max_transfer_size;
bv.bv_offset = bvec.bv_offset;
if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
goto out;
bv.bv_len = bvec.bv_len - max_transfer_size;
bv.bv_offset += max_transfer_size;
if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
goto out;
} else
if (zram_bvec_rw(zram, &bvec, index, offset, bio, rw)
< 0)
goto out;
update_position(&index, &offset, &bvec);
}
set_bit(BIO_UPTODATE, &bio->bi_flags);
bio_endio(bio, 0);
return;
out:
bio_io_error(bio);
}
/*
* Handler function for all zram I/O requests.
*/
static void zram_make_request(struct request_queue *queue, struct bio *bio)
{
struct zram *zram = queue->queuedata;
down_read(&zram->init_lock);
if (unlikely(!zram->init_done))
goto error;
if (!valid_io_request(zram, bio)) {
atomic64_inc(&zram->stats.invalid_io);
goto error;
}
__zram_make_request(zram, bio, bio_data_dir(bio));
up_read(&zram->init_lock);
return;
error:
up_read(&zram->init_lock);
bio_io_error(bio);
}
static void zram_slot_free_notify(struct block_device *bdev,
unsigned long index)
{
struct zram *zram;
struct zram_meta *meta;
zram = bdev->bd_disk->private_data;
meta = zram->meta;
write_lock(&meta->tb_lock);
zram_free_page(zram, index);
write_unlock(&meta->tb_lock);
atomic64_inc(&zram->stats.notify_free);
}
static const struct block_device_operations zram_devops = {
.swap_slot_free_notify = zram_slot_free_notify,
.owner = THIS_MODULE
};
static DEVICE_ATTR(disksize, S_IRUGO | S_IWUSR,
disksize_show, disksize_store);
static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL);
static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL);
static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL);
static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL);
static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL);
static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL);
static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
static struct attribute *zram_disk_attrs[] = {
&dev_attr_disksize.attr,
&dev_attr_initstate.attr,
&dev_attr_reset.attr,
&dev_attr_num_reads.attr,
&dev_attr_num_writes.attr,
&dev_attr_invalid_io.attr,
&dev_attr_notify_free.attr,
&dev_attr_zero_pages.attr,
&dev_attr_orig_data_size.attr,
&dev_attr_compr_data_size.attr,
&dev_attr_mem_used_total.attr,
NULL,
};
static struct attribute_group zram_disk_attr_group = {
.attrs = zram_disk_attrs,
};
static int create_device(struct zram *zram, int device_id)
{
int ret = -ENOMEM;
init_rwsem(&zram->init_lock);
zram->queue = blk_alloc_queue(GFP_KERNEL);
if (!zram->queue) {
pr_err("Error allocating disk queue for device %d\n",
device_id);
goto out;
}
blk_queue_make_request(zram->queue, zram_make_request);
zram->queue->queuedata = zram;
/* gendisk structure */
zram->disk = alloc_disk(1);
if (!zram->disk) {
pr_warn("Error allocating disk structure for device %d\n",
device_id);
goto out_free_queue;
}
zram->disk->major = zram_major;
zram->disk->first_minor = device_id;
zram->disk->fops = &zram_devops;
zram->disk->queue = zram->queue;
zram->disk->private_data = zram;
snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
set_capacity(zram->disk, 0);
/*
* To ensure that we always get PAGE_SIZE aligned
* and n*PAGE_SIZED sized I/O requests.
*/
blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
blk_queue_logical_block_size(zram->disk->queue,
ZRAM_LOGICAL_BLOCK_SIZE);
blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
add_disk(zram->disk);
ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
&zram_disk_attr_group);
if (ret < 0) {
pr_warn("Error creating sysfs group");
goto out_free_disk;
}
zram->init_done = 0;
return 0;
out_free_disk:
del_gendisk(zram->disk);
put_disk(zram->disk);
out_free_queue:
blk_cleanup_queue(zram->queue);
out:
return ret;
}
static void destroy_device(struct zram *zram)
{
sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
&zram_disk_attr_group);
del_gendisk(zram->disk);
put_disk(zram->disk);
blk_cleanup_queue(zram->queue);
}
static int __init zram_init(void)
{
int ret, dev_id;
if (num_devices > max_num_devices) {
pr_warn("Invalid value for num_devices: %u\n",
num_devices);
ret = -EINVAL;
goto out;
}
zram_major = register_blkdev(0, "zram");
if (zram_major <= 0) {
pr_warn("Unable to get major number\n");
ret = -EBUSY;
goto out;
}
/* Allocate the device array and initialize each one */
zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
if (!zram_devices) {
ret = -ENOMEM;
goto unregister;
}
for (dev_id = 0; dev_id < num_devices; dev_id++) {
ret = create_device(&zram_devices[dev_id], dev_id);
if (ret)
goto free_devices;
}
pr_info("Created %u device(s) ...\n", num_devices);
return 0;
free_devices:
while (dev_id)
destroy_device(&zram_devices[--dev_id]);
kfree(zram_devices);
unregister:
unregister_blkdev(zram_major, "zram");
out:
return ret;
}
static void __exit zram_exit(void)
{
int i;
struct zram *zram;
for (i = 0; i < num_devices; i++) {
zram = &zram_devices[i];
destroy_device(zram);
/*
* Shouldn't access zram->disk after destroy_device
* because destroy_device already released zram->disk.
*/
zram_reset_device(zram, false);
}
unregister_blkdev(zram_major, "zram");
kfree(zram_devices);
pr_debug("Cleanup done!\n");
}
module_init(zram_init);
module_exit(zram_exit);
module_param(num_devices, uint, 0);
MODULE_PARM_DESC(num_devices, "Number of zram devices");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
MODULE_DESCRIPTION("Compressed RAM Block Device");