2 * Compressed RAM block device
4 * Copyright (C) 2008, 2009, 2010 Nitin Gupta
6 * This code is released using a dual license strategy: BSD/GPL
7 * You can choose the licence that better fits your requirements.
9 * Released under the terms of 3-clause BSD License
10 * Released under the terms of GNU General Public License Version 2.0
12 * Project home: http://compcache.googlecode.com
15 #define KMSG_COMPONENT "zram"
16 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
18 #ifdef CONFIG_ZRAM_DEBUG
22 #include <linux/module.h>
23 #include <linux/kernel.h>
24 #include <linux/bio.h>
25 #include <linux/bitops.h>
26 #include <linux/blkdev.h>
27 #include <linux/buffer_head.h>
28 #include <linux/device.h>
29 #include <linux/genhd.h>
30 #include <linux/highmem.h>
31 #include <linux/slab.h>
32 #include <linux/lzo.h>
33 #include <linux/string.h>
34 #include <linux/vmalloc.h>
39 static int zram_major;
40 struct zram *zram_devices;
42 /* Module params (documentation at end) */
43 static unsigned int num_devices;
45 static void zram_stat_inc(u32 *v)
50 static void zram_stat_dec(u32 *v)
55 static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
57 spin_lock(&zram->stat64_lock);
59 spin_unlock(&zram->stat64_lock);
62 static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
64 spin_lock(&zram->stat64_lock);
66 spin_unlock(&zram->stat64_lock);
69 static void zram_stat64_inc(struct zram *zram, u64 *v)
71 zram_stat64_add(zram, v, 1);
74 static int zram_test_flag(struct zram *zram, u32 index,
75 enum zram_pageflags flag)
77 return zram->table[index].flags & BIT(flag);
80 static void zram_set_flag(struct zram *zram, u32 index,
81 enum zram_pageflags flag)
83 zram->table[index].flags |= BIT(flag);
86 static void zram_clear_flag(struct zram *zram, u32 index,
87 enum zram_pageflags flag)
89 zram->table[index].flags &= ~BIT(flag);
92 static int page_zero_filled(void *ptr)
97 page = (unsigned long *)ptr;
99 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
107 static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
109 if (!zram->disksize) {
111 "disk size not provided. You can use disksize_kb module "
112 "param to specify size.\nUsing default: (%u%% of RAM).\n",
113 default_disksize_perc_ram
115 zram->disksize = default_disksize_perc_ram *
116 (totalram_bytes / 100);
119 if (zram->disksize > 2 * (totalram_bytes)) {
121 "There is little point creating a zram of greater than "
122 "twice the size of memory since we expect a 2:1 compression "
123 "ratio. Note that zram uses about 0.1%% of the size of "
124 "the disk when not in use so a huge zram is "
126 "\tMemory Size: %zu kB\n"
127 "\tSize you selected: %llu kB\n"
128 "Continuing anyway ...\n",
129 totalram_bytes >> 10, zram->disksize
133 zram->disksize &= PAGE_MASK;
136 static void zram_free_page(struct zram *zram, size_t index)
138 unsigned long handle = zram->table[index].handle;
139 u16 size = zram->table[index].size;
141 if (unlikely(!handle)) {
143 * No memory is allocated for zero filled pages.
144 * Simply clear zero page flag.
146 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
147 zram_clear_flag(zram, index, ZRAM_ZERO);
148 zram_stat_dec(&zram->stats.pages_zero);
153 if (unlikely(size > max_zpage_size))
154 zram_stat_dec(&zram->stats.bad_compress);
156 zs_free(zram->mem_pool, handle);
158 if (size <= PAGE_SIZE / 2)
159 zram_stat_dec(&zram->stats.good_compress);
161 zram_stat64_sub(zram, &zram->stats.compr_size,
162 zram->table[index].size);
163 zram_stat_dec(&zram->stats.pages_stored);
165 zram->table[index].handle = 0;
166 zram->table[index].size = 0;
169 static void handle_zero_page(struct bio_vec *bvec)
171 struct page *page = bvec->bv_page;
174 user_mem = kmap_atomic(page);
175 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
176 kunmap_atomic(user_mem);
178 flush_dcache_page(page);
181 static inline int is_partial_io(struct bio_vec *bvec)
183 return bvec->bv_len != PAGE_SIZE;
186 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
189 size_t clen = PAGE_SIZE;
191 unsigned long handle = zram->table[index].handle;
193 if (!handle || zram_test_flag(zram, index, ZRAM_ZERO)) {
194 memset(mem, 0, PAGE_SIZE);
198 cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
199 if (zram->table[index].size == PAGE_SIZE)
200 memcpy(mem, cmem, PAGE_SIZE);
202 ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
204 zs_unmap_object(zram->mem_pool, handle);
206 /* Should NEVER happen. Return bio error if it does. */
207 if (unlikely(ret != LZO_E_OK)) {
208 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
209 zram_stat64_inc(zram, &zram->stats.failed_reads);
216 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
217 u32 index, int offset, struct bio *bio)
221 unsigned char *user_mem, *uncmem = NULL;
223 page = bvec->bv_page;
225 if (unlikely(!zram->table[index].handle) ||
226 zram_test_flag(zram, index, ZRAM_ZERO)) {
227 handle_zero_page(bvec);
231 user_mem = kmap_atomic(page);
232 if (is_partial_io(bvec))
233 /* Use a temporary buffer to decompress the page */
234 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
239 pr_info("Unable to allocate temp memory\n");
244 ret = zram_decompress_page(zram, uncmem, index);
245 /* Should NEVER happen. Return bio error if it does. */
246 if (unlikely(ret != LZO_E_OK)) {
247 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
248 zram_stat64_inc(zram, &zram->stats.failed_reads);
252 if (is_partial_io(bvec))
253 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
256 flush_dcache_page(page);
259 kunmap_atomic(user_mem);
260 if (is_partial_io(bvec))
265 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
270 unsigned long handle;
272 unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
274 page = bvec->bv_page;
275 src = zram->compress_buffer;
277 if (is_partial_io(bvec)) {
279 * This is a partial IO. We need to read the full page
280 * before to write the changes.
282 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
284 pr_info("Error allocating temp memory!\n");
288 ret = zram_decompress_page(zram, uncmem, index);
294 * System overwrites unused sectors. Free memory associated
295 * with this sector now.
297 if (zram->table[index].handle ||
298 zram_test_flag(zram, index, ZRAM_ZERO))
299 zram_free_page(zram, index);
301 user_mem = kmap_atomic(page);
303 if (is_partial_io(bvec)) {
304 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
306 kunmap_atomic(user_mem);
312 if (page_zero_filled(uncmem)) {
313 if (!is_partial_io(bvec))
314 kunmap_atomic(user_mem);
315 zram_stat_inc(&zram->stats.pages_zero);
316 zram_set_flag(zram, index, ZRAM_ZERO);
321 ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
322 zram->compress_workmem);
324 if (!is_partial_io(bvec)) {
325 kunmap_atomic(user_mem);
330 if (unlikely(ret != LZO_E_OK)) {
331 pr_err("Compression failed! err=%d\n", ret);
335 if (unlikely(clen > max_zpage_size)) {
336 zram_stat_inc(&zram->stats.bad_compress);
339 if (is_partial_io(bvec))
343 handle = zs_malloc(zram->mem_pool, clen);
345 pr_info("Error allocating memory for compressed "
346 "page: %u, size=%zu\n", index, clen);
350 cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
352 if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
353 src = kmap_atomic(page);
354 memcpy(cmem, src, clen);
355 if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
358 zs_unmap_object(zram->mem_pool, handle);
360 zram->table[index].handle = handle;
361 zram->table[index].size = clen;
364 zram_stat64_add(zram, &zram->stats.compr_size, clen);
365 zram_stat_inc(&zram->stats.pages_stored);
366 if (clen <= PAGE_SIZE / 2)
367 zram_stat_inc(&zram->stats.good_compress);
370 if (is_partial_io(bvec))
374 zram_stat64_inc(zram, &zram->stats.failed_writes);
378 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
379 int offset, struct bio *bio, int rw)
384 down_read(&zram->lock);
385 ret = zram_bvec_read(zram, bvec, index, offset, bio);
386 up_read(&zram->lock);
388 down_write(&zram->lock);
389 ret = zram_bvec_write(zram, bvec, index, offset);
390 up_write(&zram->lock);
396 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
398 if (*offset + bvec->bv_len >= PAGE_SIZE)
400 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
403 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
407 struct bio_vec *bvec;
411 zram_stat64_inc(zram, &zram->stats.num_reads);
414 zram_stat64_inc(zram, &zram->stats.num_writes);
418 index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
419 offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
421 bio_for_each_segment(bvec, bio, i) {
422 int max_transfer_size = PAGE_SIZE - offset;
424 if (bvec->bv_len > max_transfer_size) {
426 * zram_bvec_rw() can only make operation on a single
427 * zram page. Split the bio vector.
431 bv.bv_page = bvec->bv_page;
432 bv.bv_len = max_transfer_size;
433 bv.bv_offset = bvec->bv_offset;
435 if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
438 bv.bv_len = bvec->bv_len - max_transfer_size;
439 bv.bv_offset += max_transfer_size;
440 if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
443 if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
447 update_position(&index, &offset, bvec);
450 set_bit(BIO_UPTODATE, &bio->bi_flags);
459 * Check if request is within bounds and aligned on zram logical blocks.
461 static inline int valid_io_request(struct zram *zram, struct bio *bio)
464 (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
465 (bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
466 (bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
471 /* I/O request is valid */
476 * Handler function for all zram I/O requests.
478 static void zram_make_request(struct request_queue *queue, struct bio *bio)
480 struct zram *zram = queue->queuedata;
482 if (unlikely(!zram->init_done) && zram_init_device(zram))
485 down_read(&zram->init_lock);
486 if (unlikely(!zram->init_done))
489 if (!valid_io_request(zram, bio)) {
490 zram_stat64_inc(zram, &zram->stats.invalid_io);
494 __zram_make_request(zram, bio, bio_data_dir(bio));
495 up_read(&zram->init_lock);
500 up_read(&zram->init_lock);
505 void __zram_reset_device(struct zram *zram)
511 /* Free various per-device buffers */
512 kfree(zram->compress_workmem);
513 free_pages((unsigned long)zram->compress_buffer, 1);
515 zram->compress_workmem = NULL;
516 zram->compress_buffer = NULL;
518 /* Free all pages that are still in this zram device */
519 for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
520 unsigned long handle = zram->table[index].handle;
524 zs_free(zram->mem_pool, handle);
530 zs_destroy_pool(zram->mem_pool);
531 zram->mem_pool = NULL;
534 memset(&zram->stats, 0, sizeof(zram->stats));
539 void zram_reset_device(struct zram *zram)
541 down_write(&zram->init_lock);
542 __zram_reset_device(zram);
543 up_write(&zram->init_lock);
546 int zram_init_device(struct zram *zram)
551 down_write(&zram->init_lock);
553 if (zram->init_done) {
554 up_write(&zram->init_lock);
558 zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
560 zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
561 if (!zram->compress_workmem) {
562 pr_err("Error allocating compressor working memory!\n");
567 zram->compress_buffer =
568 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
569 if (!zram->compress_buffer) {
570 pr_err("Error allocating compressor buffer space\n");
575 num_pages = zram->disksize >> PAGE_SHIFT;
576 zram->table = vzalloc(num_pages * sizeof(*zram->table));
578 pr_err("Error allocating zram address table\n");
583 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
585 /* zram devices sort of resembles non-rotational disks */
586 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
588 zram->mem_pool = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
589 if (!zram->mem_pool) {
590 pr_err("Error creating memory pool\n");
596 up_write(&zram->init_lock);
598 pr_debug("Initialization done!\n");
602 /* To prevent accessing table entries during cleanup */
605 __zram_reset_device(zram);
606 up_write(&zram->init_lock);
607 pr_err("Initialization failed: err=%d\n", ret);
611 static void zram_slot_free_notify(struct block_device *bdev,
616 zram = bdev->bd_disk->private_data;
617 zram_free_page(zram, index);
618 zram_stat64_inc(zram, &zram->stats.notify_free);
621 static const struct block_device_operations zram_devops = {
622 .swap_slot_free_notify = zram_slot_free_notify,
626 static int create_device(struct zram *zram, int device_id)
630 init_rwsem(&zram->lock);
631 init_rwsem(&zram->init_lock);
632 spin_lock_init(&zram->stat64_lock);
634 zram->queue = blk_alloc_queue(GFP_KERNEL);
636 pr_err("Error allocating disk queue for device %d\n",
642 blk_queue_make_request(zram->queue, zram_make_request);
643 zram->queue->queuedata = zram;
645 /* gendisk structure */
646 zram->disk = alloc_disk(1);
648 blk_cleanup_queue(zram->queue);
649 pr_warn("Error allocating disk structure for device %d\n",
655 zram->disk->major = zram_major;
656 zram->disk->first_minor = device_id;
657 zram->disk->fops = &zram_devops;
658 zram->disk->queue = zram->queue;
659 zram->disk->private_data = zram;
660 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
662 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
663 set_capacity(zram->disk, 0);
666 * To ensure that we always get PAGE_SIZE aligned
667 * and n*PAGE_SIZED sized I/O requests.
669 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
670 blk_queue_logical_block_size(zram->disk->queue,
671 ZRAM_LOGICAL_BLOCK_SIZE);
672 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
673 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
675 add_disk(zram->disk);
677 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
678 &zram_disk_attr_group);
680 pr_warn("Error creating sysfs group");
690 static void destroy_device(struct zram *zram)
692 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
693 &zram_disk_attr_group);
696 del_gendisk(zram->disk);
697 put_disk(zram->disk);
701 blk_cleanup_queue(zram->queue);
704 unsigned int zram_get_num_devices(void)
709 static int __init zram_init(void)
713 if (num_devices > max_num_devices) {
714 pr_warn("Invalid value for num_devices: %u\n",
720 zram_major = register_blkdev(0, "zram");
721 if (zram_major <= 0) {
722 pr_warn("Unable to get major number\n");
728 pr_info("num_devices not specified. Using default: 1\n");
732 /* Allocate the device array and initialize each one */
733 pr_info("Creating %u devices ...\n", num_devices);
734 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
740 for (dev_id = 0; dev_id < num_devices; dev_id++) {
741 ret = create_device(&zram_devices[dev_id], dev_id);
750 destroy_device(&zram_devices[--dev_id]);
753 unregister_blkdev(zram_major, "zram");
758 static void __exit zram_exit(void)
763 for (i = 0; i < num_devices; i++) {
764 zram = &zram_devices[i];
766 destroy_device(zram);
768 zram_reset_device(zram);
771 unregister_blkdev(zram_major, "zram");
774 pr_debug("Cleanup done!\n");
777 module_param(num_devices, uint, 0);
778 MODULE_PARM_DESC(num_devices, "Number of zram devices");
780 module_init(zram_init);
781 module_exit(zram_exit);
783 MODULE_LICENSE("Dual BSD/GPL");
784 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
785 MODULE_DESCRIPTION("Compressed RAM Block Device");