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 static struct zram *zram_devices;
42 /* Module params (documentation at end) */
43 static unsigned int num_devices = 1;
45 static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
47 spin_lock(&zram->stat64_lock);
49 spin_unlock(&zram->stat64_lock);
52 static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
54 spin_lock(&zram->stat64_lock);
56 spin_unlock(&zram->stat64_lock);
59 static void zram_stat64_inc(struct zram *zram, u64 *v)
61 zram_stat64_add(zram, v, 1);
64 static int zram_test_flag(struct zram_meta *meta, u32 index,
65 enum zram_pageflags flag)
67 return meta->table[index].flags & BIT(flag);
70 static void zram_set_flag(struct zram_meta *meta, u32 index,
71 enum zram_pageflags flag)
73 meta->table[index].flags |= BIT(flag);
76 static void zram_clear_flag(struct zram_meta *meta, u32 index,
77 enum zram_pageflags flag)
79 meta->table[index].flags &= ~BIT(flag);
82 static int page_zero_filled(void *ptr)
87 page = (unsigned long *)ptr;
89 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
97 static void zram_free_page(struct zram *zram, size_t index)
99 struct zram_meta *meta = zram->meta;
100 unsigned long handle = meta->table[index].handle;
101 u16 size = meta->table[index].size;
103 if (unlikely(!handle)) {
105 * No memory is allocated for zero filled pages.
106 * Simply clear zero page flag.
108 if (zram_test_flag(meta, index, ZRAM_ZERO)) {
109 zram_clear_flag(meta, index, ZRAM_ZERO);
110 zram->stats.pages_zero--;
115 if (unlikely(size > max_zpage_size))
116 zram->stats.bad_compress--;
118 zs_free(meta->mem_pool, handle);
120 if (size <= PAGE_SIZE / 2)
121 zram->stats.good_compress--;
123 zram_stat64_sub(zram, &zram->stats.compr_size,
124 meta->table[index].size);
125 zram->stats.pages_stored--;
127 meta->table[index].handle = 0;
128 meta->table[index].size = 0;
131 static void handle_zero_page(struct bio_vec *bvec)
133 struct page *page = bvec->bv_page;
136 user_mem = kmap_atomic(page);
137 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
138 kunmap_atomic(user_mem);
140 flush_dcache_page(page);
143 static inline int is_partial_io(struct bio_vec *bvec)
145 return bvec->bv_len != PAGE_SIZE;
148 static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
151 size_t clen = PAGE_SIZE;
153 struct zram_meta *meta = zram->meta;
154 unsigned long handle = meta->table[index].handle;
156 if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
157 memset(mem, 0, PAGE_SIZE);
161 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
162 if (meta->table[index].size == PAGE_SIZE)
163 memcpy(mem, cmem, PAGE_SIZE);
165 ret = lzo1x_decompress_safe(cmem, meta->table[index].size,
167 zs_unmap_object(meta->mem_pool, handle);
169 /* Should NEVER happen. Return bio error if it does. */
170 if (unlikely(ret != LZO_E_OK)) {
171 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
172 zram_stat64_inc(zram, &zram->stats.failed_reads);
179 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
180 u32 index, int offset, struct bio *bio)
184 unsigned char *user_mem, *uncmem = NULL;
185 struct zram_meta *meta = zram->meta;
186 page = bvec->bv_page;
188 if (unlikely(!meta->table[index].handle) ||
189 zram_test_flag(meta, index, ZRAM_ZERO)) {
190 handle_zero_page(bvec);
194 if (is_partial_io(bvec))
195 /* Use a temporary buffer to decompress the page */
196 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
198 user_mem = kmap_atomic(page);
199 if (!is_partial_io(bvec))
203 pr_info("Unable to allocate temp memory\n");
208 ret = zram_decompress_page(zram, uncmem, index);
209 /* Should NEVER happen. Return bio error if it does. */
210 if (unlikely(ret != LZO_E_OK))
213 if (is_partial_io(bvec))
214 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
217 flush_dcache_page(page);
220 kunmap_atomic(user_mem);
221 if (is_partial_io(bvec))
226 static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
231 unsigned long handle;
233 unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
234 struct zram_meta *meta = zram->meta;
236 page = bvec->bv_page;
237 src = meta->compress_buffer;
239 if (is_partial_io(bvec)) {
241 * This is a partial IO. We need to read the full page
242 * before to write the changes.
244 uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
249 ret = zram_decompress_page(zram, uncmem, index);
255 * System overwrites unused sectors. Free memory associated
256 * with this sector now.
258 if (meta->table[index].handle ||
259 zram_test_flag(meta, index, ZRAM_ZERO))
260 zram_free_page(zram, index);
262 user_mem = kmap_atomic(page);
264 if (is_partial_io(bvec)) {
265 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
267 kunmap_atomic(user_mem);
273 if (page_zero_filled(uncmem)) {
274 kunmap_atomic(user_mem);
275 zram->stats.pages_zero++;
276 zram_set_flag(meta, index, ZRAM_ZERO);
281 ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
282 meta->compress_workmem);
284 if (!is_partial_io(bvec)) {
285 kunmap_atomic(user_mem);
290 if (unlikely(ret != LZO_E_OK)) {
291 pr_err("Compression failed! err=%d\n", ret);
295 if (unlikely(clen > max_zpage_size)) {
296 zram->stats.bad_compress++;
299 if (is_partial_io(bvec))
303 handle = zs_malloc(meta->mem_pool, clen);
305 pr_info("Error allocating memory for compressed page: %u, size=%zu\n",
310 cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
312 if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
313 src = kmap_atomic(page);
314 memcpy(cmem, src, clen);
315 if ((clen == PAGE_SIZE) && !is_partial_io(bvec))
318 zs_unmap_object(meta->mem_pool, handle);
320 meta->table[index].handle = handle;
321 meta->table[index].size = clen;
324 zram_stat64_add(zram, &zram->stats.compr_size, clen);
325 zram->stats.pages_stored++;
326 if (clen <= PAGE_SIZE / 2)
327 zram->stats.good_compress++;
330 if (is_partial_io(bvec))
334 zram_stat64_inc(zram, &zram->stats.failed_writes);
338 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
339 int offset, struct bio *bio, int rw)
344 down_read(&zram->lock);
345 ret = zram_bvec_read(zram, bvec, index, offset, bio);
346 up_read(&zram->lock);
348 down_write(&zram->lock);
349 ret = zram_bvec_write(zram, bvec, index, offset);
350 up_write(&zram->lock);
356 static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
358 if (*offset + bvec->bv_len >= PAGE_SIZE)
360 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
363 static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
367 struct bio_vec *bvec;
371 zram_stat64_inc(zram, &zram->stats.num_reads);
374 zram_stat64_inc(zram, &zram->stats.num_writes);
378 index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
379 offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
381 bio_for_each_segment(bvec, bio, i) {
382 int max_transfer_size = PAGE_SIZE - offset;
384 if (bvec->bv_len > max_transfer_size) {
386 * zram_bvec_rw() can only make operation on a single
387 * zram page. Split the bio vector.
391 bv.bv_page = bvec->bv_page;
392 bv.bv_len = max_transfer_size;
393 bv.bv_offset = bvec->bv_offset;
395 if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
398 bv.bv_len = bvec->bv_len - max_transfer_size;
399 bv.bv_offset += max_transfer_size;
400 if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
403 if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
407 update_position(&index, &offset, bvec);
410 set_bit(BIO_UPTODATE, &bio->bi_flags);
419 * Check if request is within bounds and aligned on zram logical blocks.
421 static inline int valid_io_request(struct zram *zram, struct bio *bio)
423 u64 start, end, bound;
425 /* unaligned request */
426 if (unlikely(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
428 if (unlikely(bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))
431 start = bio->bi_sector;
432 end = start + (bio->bi_size >> SECTOR_SHIFT);
433 bound = zram->disksize >> SECTOR_SHIFT;
434 /* out of range range */
435 if (unlikely(start >= bound || end > bound || start > end))
438 /* I/O request is valid */
443 * Handler function for all zram I/O requests.
445 static void zram_make_request(struct request_queue *queue, struct bio *bio)
447 struct zram *zram = queue->queuedata;
449 down_read(&zram->init_lock);
450 if (unlikely(!zram->init_done))
453 if (!valid_io_request(zram, bio)) {
454 zram_stat64_inc(zram, &zram->stats.invalid_io);
458 __zram_make_request(zram, bio, bio_data_dir(bio));
459 up_read(&zram->init_lock);
464 up_read(&zram->init_lock);
468 static void __zram_reset_device(struct zram *zram)
471 struct zram_meta *meta;
473 if (!zram->init_done)
479 /* Free all pages that are still in this zram device */
480 for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
481 unsigned long handle = meta->table[index].handle;
485 zs_free(meta->mem_pool, handle);
488 zram_meta_free(zram->meta);
491 memset(&zram->stats, 0, sizeof(zram->stats));
494 set_capacity(zram->disk, 0);
497 void zram_reset_device(struct zram *zram)
499 down_write(&zram->init_lock);
500 __zram_reset_device(zram);
501 up_write(&zram->init_lock);
504 void zram_meta_free(struct zram_meta *meta)
506 zs_destroy_pool(meta->mem_pool);
507 kfree(meta->compress_workmem);
508 free_pages((unsigned long)meta->compress_buffer, 1);
513 struct zram_meta *zram_meta_alloc(u64 disksize)
516 struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
520 meta->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
521 if (!meta->compress_workmem)
524 meta->compress_buffer =
525 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
526 if (!meta->compress_buffer) {
527 pr_err("Error allocating compressor buffer space\n");
531 num_pages = disksize >> PAGE_SHIFT;
532 meta->table = vzalloc(num_pages * sizeof(*meta->table));
534 pr_err("Error allocating zram address table\n");
538 meta->mem_pool = zs_create_pool(GFP_NOIO | __GFP_HIGHMEM);
539 if (!meta->mem_pool) {
540 pr_err("Error creating memory pool\n");
549 free_pages((unsigned long)meta->compress_buffer, 1);
551 kfree(meta->compress_workmem);
559 void zram_init_device(struct zram *zram, struct zram_meta *meta)
561 if (zram->disksize > 2 * (totalram_pages << PAGE_SHIFT)) {
563 "There is little point creating a zram of greater than "
564 "twice the size of memory since we expect a 2:1 compression "
565 "ratio. Note that zram uses about 0.1%% of the size of "
566 "the disk when not in use so a huge zram is "
568 "\tMemory Size: %lu kB\n"
569 "\tSize you selected: %llu kB\n"
570 "Continuing anyway ...\n",
571 (totalram_pages << PAGE_SHIFT) >> 10, zram->disksize >> 10
575 /* zram devices sort of resembles non-rotational disks */
576 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
581 pr_debug("Initialization done!\n");
584 static void zram_slot_free_notify(struct block_device *bdev,
589 zram = bdev->bd_disk->private_data;
590 down_write(&zram->lock);
591 zram_free_page(zram, index);
592 up_write(&zram->lock);
593 zram_stat64_inc(zram, &zram->stats.notify_free);
596 static const struct block_device_operations zram_devops = {
597 .swap_slot_free_notify = zram_slot_free_notify,
601 static int create_device(struct zram *zram, int device_id)
605 init_rwsem(&zram->lock);
606 init_rwsem(&zram->init_lock);
607 spin_lock_init(&zram->stat64_lock);
609 zram->queue = blk_alloc_queue(GFP_KERNEL);
611 pr_err("Error allocating disk queue for device %d\n",
616 blk_queue_make_request(zram->queue, zram_make_request);
617 zram->queue->queuedata = zram;
619 /* gendisk structure */
620 zram->disk = alloc_disk(1);
622 pr_warn("Error allocating disk structure for device %d\n",
627 zram->disk->major = zram_major;
628 zram->disk->first_minor = device_id;
629 zram->disk->fops = &zram_devops;
630 zram->disk->queue = zram->queue;
631 zram->disk->private_data = zram;
632 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
634 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
635 set_capacity(zram->disk, 0);
638 * To ensure that we always get PAGE_SIZE aligned
639 * and n*PAGE_SIZED sized I/O requests.
641 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
642 blk_queue_logical_block_size(zram->disk->queue,
643 ZRAM_LOGICAL_BLOCK_SIZE);
644 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
645 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
647 add_disk(zram->disk);
649 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
650 &zram_disk_attr_group);
652 pr_warn("Error creating sysfs group");
660 del_gendisk(zram->disk);
661 put_disk(zram->disk);
663 blk_cleanup_queue(zram->queue);
668 static void destroy_device(struct zram *zram)
670 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
671 &zram_disk_attr_group);
674 del_gendisk(zram->disk);
675 put_disk(zram->disk);
679 blk_cleanup_queue(zram->queue);
682 static int __init zram_init(void)
686 if (num_devices > max_num_devices) {
687 pr_warn("Invalid value for num_devices: %u\n",
693 zram_major = register_blkdev(0, "zram");
694 if (zram_major <= 0) {
695 pr_warn("Unable to get major number\n");
700 /* Allocate the device array and initialize each one */
701 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
707 for (dev_id = 0; dev_id < num_devices; dev_id++) {
708 ret = create_device(&zram_devices[dev_id], dev_id);
713 pr_info("Created %u device(s) ...\n", num_devices);
719 destroy_device(&zram_devices[--dev_id]);
722 unregister_blkdev(zram_major, "zram");
727 static void __exit zram_exit(void)
732 for (i = 0; i < num_devices; i++) {
733 zram = &zram_devices[i];
735 get_disk(zram->disk);
736 destroy_device(zram);
737 zram_reset_device(zram);
738 put_disk(zram->disk);
741 unregister_blkdev(zram_major, "zram");
744 pr_debug("Cleanup done!\n");
747 module_param(num_devices, uint, 0);
748 MODULE_PARM_DESC(num_devices, "Number of zram devices");
750 module_init(zram_init);
751 module_exit(zram_exit);
753 MODULE_LICENSE("Dual BSD/GPL");
754 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
755 MODULE_DESCRIPTION("Compressed RAM Block Device");