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1/*
2 * Compressed RAM block device
3 *
4 * Copyright (C) 2008, 2009, 2010 Nitin Gupta
5 *
6 * This code is released using a dual license strategy: BSD/GPL
7 * You can choose the licence that better fits your requirements.
8 *
9 * Released under the terms of 3-clause BSD License
10 * Released under the terms of GNU General Public License Version 2.0
11 *
12 * Project home: http://compcache.googlecode.com
13 */
14
15#define KMSG_COMPONENT "zram"
16#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
17
18#ifdef CONFIG_ZRAM_DEBUG
19#define DEBUG
20#endif
21
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>
35
36#include "zram_drv.h"
37
38/* Globals */
39static int zram_major;
40struct zram *zram_devices;
41
42/* Module params (documentation at end) */
43static unsigned int num_devices;
44
45static void zram_stat_inc(u32 *v)
46{
47 *v = *v + 1;
48}
49
50static void zram_stat_dec(u32 *v)
51{
52 *v = *v - 1;
53}
54
55static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc)
56{
57 spin_lock(&zram->stat64_lock);
58 *v = *v + inc;
59 spin_unlock(&zram->stat64_lock);
60}
61
62static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec)
63{
64 spin_lock(&zram->stat64_lock);
65 *v = *v - dec;
66 spin_unlock(&zram->stat64_lock);
67}
68
69static void zram_stat64_inc(struct zram *zram, u64 *v)
70{
71 zram_stat64_add(zram, v, 1);
72}
73
74static int zram_test_flag(struct zram *zram, u32 index,
75 enum zram_pageflags flag)
76{
77 return zram->table[index].flags & BIT(flag);
78}
79
80static void zram_set_flag(struct zram *zram, u32 index,
81 enum zram_pageflags flag)
82{
83 zram->table[index].flags |= BIT(flag);
84}
85
86static void zram_clear_flag(struct zram *zram, u32 index,
87 enum zram_pageflags flag)
88{
89 zram->table[index].flags &= ~BIT(flag);
90}
91
92static int page_zero_filled(void *ptr)
93{
94 unsigned int pos;
95 unsigned long *page;
96
97 page = (unsigned long *)ptr;
98
99 for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
100 if (page[pos])
101 return 0;
102 }
103
104 return 1;
105}
106
107static void zram_set_disksize(struct zram *zram, size_t totalram_bytes)
108{
109 if (!zram->disksize) {
110 pr_info(
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
114 );
115 zram->disksize = default_disksize_perc_ram *
116 (totalram_bytes / 100);
117 }
118
119 if (zram->disksize > 2 * (totalram_bytes)) {
120 pr_info(
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 "
125 "wasteful.\n"
126 "\tMemory Size: %zu kB\n"
127 "\tSize you selected: %llu kB\n"
128 "Continuing anyway ...\n",
129 totalram_bytes >> 10, zram->disksize
130 );
131 }
132
133 zram->disksize &= PAGE_MASK;
134}
135
136static void zram_free_page(struct zram *zram, size_t index)
137{
138 void *handle = zram->table[index].handle;
139
140 if (unlikely(!handle)) {
141 /*
142 * No memory is allocated for zero filled pages.
143 * Simply clear zero page flag.
144 */
145 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
146 zram_clear_flag(zram, index, ZRAM_ZERO);
147 zram_stat_dec(&zram->stats.pages_zero);
148 }
149 return;
150 }
151
152 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
153 __free_page(handle);
154 zram_clear_flag(zram, index, ZRAM_UNCOMPRESSED);
155 zram_stat_dec(&zram->stats.pages_expand);
156 goto out;
157 }
158
159 zs_free(zram->mem_pool, handle);
160
161 if (zram->table[index].size <= PAGE_SIZE / 2)
162 zram_stat_dec(&zram->stats.good_compress);
163
164out:
165 zram_stat64_sub(zram, &zram->stats.compr_size,
166 zram->table[index].size);
167 zram_stat_dec(&zram->stats.pages_stored);
168
169 zram->table[index].handle = NULL;
170 zram->table[index].size = 0;
171}
172
173static void handle_zero_page(struct bio_vec *bvec)
174{
175 struct page *page = bvec->bv_page;
176 void *user_mem;
177
178 user_mem = kmap_atomic(page);
179 memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
180 kunmap_atomic(user_mem);
181
182 flush_dcache_page(page);
183}
184
185static void handle_uncompressed_page(struct zram *zram, struct bio_vec *bvec,
186 u32 index, int offset)
187{
188 struct page *page = bvec->bv_page;
189 unsigned char *user_mem, *cmem;
190
191 user_mem = kmap_atomic(page);
192 cmem = kmap_atomic(zram->table[index].handle);
193
194 memcpy(user_mem + bvec->bv_offset, cmem + offset, bvec->bv_len);
195 kunmap_atomic(cmem);
196 kunmap_atomic(user_mem);
197
198 flush_dcache_page(page);
199}
200
201static inline int is_partial_io(struct bio_vec *bvec)
202{
203 return bvec->bv_len != PAGE_SIZE;
204}
205
206static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
207 u32 index, int offset, struct bio *bio)
208{
209 int ret;
210 size_t clen;
211 struct page *page;
212 struct zobj_header *zheader;
213 unsigned char *user_mem, *cmem, *uncmem = NULL;
214
215 page = bvec->bv_page;
216
217 if (zram_test_flag(zram, index, ZRAM_ZERO)) {
218 handle_zero_page(bvec);
219 return 0;
220 }
221
222 /* Requested page is not present in compressed area */
223 if (unlikely(!zram->table[index].handle)) {
224 pr_debug("Read before write: sector=%lu, size=%u",
225 (ulong)(bio->bi_sector), bio->bi_size);
226 handle_zero_page(bvec);
227 return 0;
228 }
229
230 /* Page is stored uncompressed since it's incompressible */
231 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
232 handle_uncompressed_page(zram, bvec, index, offset);
233 return 0;
234 }
235
236 if (is_partial_io(bvec)) {
237 /* Use a temporary buffer to decompress the page */
238 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
239 if (!uncmem) {
240 pr_info("Error allocating temp memory!\n");
241 return -ENOMEM;
242 }
243 }
244
245 user_mem = kmap_atomic(page);
246 if (!is_partial_io(bvec))
247 uncmem = user_mem;
248 clen = PAGE_SIZE;
249
250 cmem = zs_map_object(zram->mem_pool, zram->table[index].handle);
251
252 ret = lzo1x_decompress_safe(cmem + sizeof(*zheader),
253 zram->table[index].size,
254 uncmem, &clen);
255
256 if (is_partial_io(bvec)) {
257 memcpy(user_mem + bvec->bv_offset, uncmem + offset,
258 bvec->bv_len);
259 kfree(uncmem);
260 }
261
262 zs_unmap_object(zram->mem_pool, zram->table[index].handle);
263 kunmap_atomic(user_mem);
264
265 /* Should NEVER happen. Return bio error if it does. */
266 if (unlikely(ret != LZO_E_OK)) {
267 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
268 zram_stat64_inc(zram, &zram->stats.failed_reads);
269 return ret;
270 }
271
272 flush_dcache_page(page);
273
274 return 0;
275}
276
277static int zram_read_before_write(struct zram *zram, char *mem, u32 index)
278{
279 int ret;
280 size_t clen = PAGE_SIZE;
281 struct zobj_header *zheader;
282 unsigned char *cmem;
283
284 if (zram_test_flag(zram, index, ZRAM_ZERO) ||
285 !zram->table[index].handle) {
286 memset(mem, 0, PAGE_SIZE);
287 return 0;
288 }
289
290 cmem = zs_map_object(zram->mem_pool, zram->table[index].handle);
291
292 /* Page is stored uncompressed since it's incompressible */
293 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
294 memcpy(mem, cmem, PAGE_SIZE);
295 kunmap_atomic(cmem);
296 return 0;
297 }
298
299 ret = lzo1x_decompress_safe(cmem + sizeof(*zheader),
300 zram->table[index].size,
301 mem, &clen);
302 zs_unmap_object(zram->mem_pool, zram->table[index].handle);
303
304 /* Should NEVER happen. Return bio error if it does. */
305 if (unlikely(ret != LZO_E_OK)) {
306 pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
307 zram_stat64_inc(zram, &zram->stats.failed_reads);
308 return ret;
309 }
310
311 return 0;
312}
313
314static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
315 int offset)
316{
317 int ret;
318 u32 store_offset;
319 size_t clen;
320 void *handle;
321 struct zobj_header *zheader;
322 struct page *page, *page_store;
323 unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
324
325 page = bvec->bv_page;
326 src = zram->compress_buffer;
327
328 if (is_partial_io(bvec)) {
329 /*
330 * This is a partial IO. We need to read the full page
331 * before to write the changes.
332 */
333 uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
334 if (!uncmem) {
335 pr_info("Error allocating temp memory!\n");
336 ret = -ENOMEM;
337 goto out;
338 }
339 ret = zram_read_before_write(zram, uncmem, index);
340 if (ret) {
341 kfree(uncmem);
342 goto out;
343 }
344 }
345
346 /*
347 * System overwrites unused sectors. Free memory associated
348 * with this sector now.
349 */
350 if (zram->table[index].handle ||
351 zram_test_flag(zram, index, ZRAM_ZERO))
352 zram_free_page(zram, index);
353
354 user_mem = kmap_atomic(page);
355
356 if (is_partial_io(bvec))
357 memcpy(uncmem + offset, user_mem + bvec->bv_offset,
358 bvec->bv_len);
359 else
360 uncmem = user_mem;
361
362 if (page_zero_filled(uncmem)) {
363 kunmap_atomic(user_mem);
364 if (is_partial_io(bvec))
365 kfree(uncmem);
366 zram_stat_inc(&zram->stats.pages_zero);
367 zram_set_flag(zram, index, ZRAM_ZERO);
368 ret = 0;
369 goto out;
370 }
371
372 ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
373 zram->compress_workmem);
374
375 kunmap_atomic(user_mem);
376 if (is_partial_io(bvec))
377 kfree(uncmem);
378
379 if (unlikely(ret != LZO_E_OK)) {
380 pr_err("Compression failed! err=%d\n", ret);
381 goto out;
382 }
383
384 /*
385 * Page is incompressible. Store it as-is (uncompressed)
386 * since we do not want to return too many disk write
387 * errors which has side effect of hanging the system.
388 */
389 if (unlikely(clen > max_zpage_size)) {
390 clen = PAGE_SIZE;
391 page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
392 if (unlikely(!page_store)) {
393 pr_info("Error allocating memory for "
394 "incompressible page: %u\n", index);
395 ret = -ENOMEM;
396 goto out;
397 }
398
399 store_offset = 0;
400 zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
401 zram_stat_inc(&zram->stats.pages_expand);
402 handle = page_store;
403 src = kmap_atomic(page);
404 cmem = kmap_atomic(page_store);
405 goto memstore;
406 }
407
408 handle = zs_malloc(zram->mem_pool, clen + sizeof(*zheader));
409 if (!handle) {
410 pr_info("Error allocating memory for compressed "
411 "page: %u, size=%zu\n", index, clen);
412 ret = -ENOMEM;
413 goto out;
414 }
415 cmem = zs_map_object(zram->mem_pool, handle);
416
417memstore:
418#if 0
419 /* Back-reference needed for memory defragmentation */
420 if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) {
421 zheader = (struct zobj_header *)cmem;
422 zheader->table_idx = index;
423 cmem += sizeof(*zheader);
424 }
425#endif
426
427 memcpy(cmem, src, clen);
428
429 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
430 kunmap_atomic(cmem);
431 kunmap_atomic(src);
432 } else {
433 zs_unmap_object(zram->mem_pool, handle);
434 }
435
436 zram->table[index].handle = handle;
437 zram->table[index].size = clen;
438
439 /* Update stats */
440 zram_stat64_add(zram, &zram->stats.compr_size, clen);
441 zram_stat_inc(&zram->stats.pages_stored);
442 if (clen <= PAGE_SIZE / 2)
443 zram_stat_inc(&zram->stats.good_compress);
444
445 return 0;
446
447out:
448 if (ret)
449 zram_stat64_inc(zram, &zram->stats.failed_writes);
450 return ret;
451}
452
453static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
454 int offset, struct bio *bio, int rw)
455{
456 int ret;
457
458 if (rw == READ) {
459 down_read(&zram->lock);
460 ret = zram_bvec_read(zram, bvec, index, offset, bio);
461 up_read(&zram->lock);
462 } else {
463 down_write(&zram->lock);
464 ret = zram_bvec_write(zram, bvec, index, offset);
465 up_write(&zram->lock);
466 }
467
468 return ret;
469}
470
471static void update_position(u32 *index, int *offset, struct bio_vec *bvec)
472{
473 if (*offset + bvec->bv_len >= PAGE_SIZE)
474 (*index)++;
475 *offset = (*offset + bvec->bv_len) % PAGE_SIZE;
476}
477
478static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
479{
480 int i, offset;
481 u32 index;
482 struct bio_vec *bvec;
483
484 switch (rw) {
485 case READ:
486 zram_stat64_inc(zram, &zram->stats.num_reads);
487 break;
488 case WRITE:
489 zram_stat64_inc(zram, &zram->stats.num_writes);
490 break;
491 }
492
493 index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
494 offset = (bio->bi_sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
495
496 bio_for_each_segment(bvec, bio, i) {
497 int max_transfer_size = PAGE_SIZE - offset;
498
499 if (bvec->bv_len > max_transfer_size) {
500 /*
501 * zram_bvec_rw() can only make operation on a single
502 * zram page. Split the bio vector.
503 */
504 struct bio_vec bv;
505
506 bv.bv_page = bvec->bv_page;
507 bv.bv_len = max_transfer_size;
508 bv.bv_offset = bvec->bv_offset;
509
510 if (zram_bvec_rw(zram, &bv, index, offset, bio, rw) < 0)
511 goto out;
512
513 bv.bv_len = bvec->bv_len - max_transfer_size;
514 bv.bv_offset += max_transfer_size;
515 if (zram_bvec_rw(zram, &bv, index+1, 0, bio, rw) < 0)
516 goto out;
517 } else
518 if (zram_bvec_rw(zram, bvec, index, offset, bio, rw)
519 < 0)
520 goto out;
521
522 update_position(&index, &offset, bvec);
523 }
524
525 set_bit(BIO_UPTODATE, &bio->bi_flags);
526 bio_endio(bio, 0);
527 return;
528
529out:
530 bio_io_error(bio);
531}
532
533/*
534 * Check if request is within bounds and aligned on zram logical blocks.
535 */
536static inline int valid_io_request(struct zram *zram, struct bio *bio)
537{
538 if (unlikely(
539 (bio->bi_sector >= (zram->disksize >> SECTOR_SHIFT)) ||
540 (bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)) ||
541 (bio->bi_size & (ZRAM_LOGICAL_BLOCK_SIZE - 1)))) {
542
543 return 0;
544 }
545
546 /* I/O request is valid */
547 return 1;
548}
549
550/*
551 * Handler function for all zram I/O requests.
552 */
553static void zram_make_request(struct request_queue *queue, struct bio *bio)
554{
555 struct zram *zram = queue->queuedata;
556
557 if (unlikely(!zram->init_done) && zram_init_device(zram))
558 goto error;
559
560 down_read(&zram->init_lock);
561 if (unlikely(!zram->init_done))
562 goto error_unlock;
563
564 if (!valid_io_request(zram, bio)) {
565 zram_stat64_inc(zram, &zram->stats.invalid_io);
566 goto error_unlock;
567 }
568
569 __zram_make_request(zram, bio, bio_data_dir(bio));
570 up_read(&zram->init_lock);
571
572 return;
573
574error_unlock:
575 up_read(&zram->init_lock);
576error:
577 bio_io_error(bio);
578}
579
580void __zram_reset_device(struct zram *zram)
581{
582 size_t index;
583
584 zram->init_done = 0;
585
586 /* Free various per-device buffers */
587 kfree(zram->compress_workmem);
588 free_pages((unsigned long)zram->compress_buffer, 1);
589
590 zram->compress_workmem = NULL;
591 zram->compress_buffer = NULL;
592
593 /* Free all pages that are still in this zram device */
594 for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
595 void *handle = zram->table[index].handle;
596 if (!handle)
597 continue;
598
599 if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
600 __free_page(handle);
601 else
602 zs_free(zram->mem_pool, handle);
603 }
604
605 vfree(zram->table);
606 zram->table = NULL;
607
608 zs_destroy_pool(zram->mem_pool);
609 zram->mem_pool = NULL;
610
611 /* Reset stats */
612 memset(&zram->stats, 0, sizeof(zram->stats));
613
614 zram->disksize = 0;
615}
616
617void zram_reset_device(struct zram *zram)
618{
619 down_write(&zram->init_lock);
620 __zram_reset_device(zram);
621 up_write(&zram->init_lock);
622}
623
624int zram_init_device(struct zram *zram)
625{
626 int ret;
627 size_t num_pages;
628
629 down_write(&zram->init_lock);
630
631 if (zram->init_done) {
632 up_write(&zram->init_lock);
633 return 0;
634 }
635
636 zram_set_disksize(zram, totalram_pages << PAGE_SHIFT);
637
638 zram->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
639 if (!zram->compress_workmem) {
640 pr_err("Error allocating compressor working memory!\n");
641 ret = -ENOMEM;
642 goto fail_no_table;
643 }
644
645 zram->compress_buffer =
646 (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
647 if (!zram->compress_buffer) {
648 pr_err("Error allocating compressor buffer space\n");
649 ret = -ENOMEM;
650 goto fail_no_table;
651 }
652
653 num_pages = zram->disksize >> PAGE_SHIFT;
654 zram->table = vzalloc(num_pages * sizeof(*zram->table));
655 if (!zram->table) {
656 pr_err("Error allocating zram address table\n");
657 ret = -ENOMEM;
658 goto fail_no_table;
659 }
660
661 set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
662
663 /* zram devices sort of resembles non-rotational disks */
664 queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
665
666 zram->mem_pool = zs_create_pool("zram", GFP_NOIO | __GFP_HIGHMEM);
667 if (!zram->mem_pool) {
668 pr_err("Error creating memory pool\n");
669 ret = -ENOMEM;
670 goto fail;
671 }
672
673 zram->init_done = 1;
674 up_write(&zram->init_lock);
675
676 pr_debug("Initialization done!\n");
677 return 0;
678
679fail_no_table:
680 /* To prevent accessing table entries during cleanup */
681 zram->disksize = 0;
682fail:
683 __zram_reset_device(zram);
684 up_write(&zram->init_lock);
685 pr_err("Initialization failed: err=%d\n", ret);
686 return ret;
687}
688
689static void zram_slot_free_notify(struct block_device *bdev,
690 unsigned long index)
691{
692 struct zram *zram;
693
694 zram = bdev->bd_disk->private_data;
695 zram_free_page(zram, index);
696 zram_stat64_inc(zram, &zram->stats.notify_free);
697}
698
699static const struct block_device_operations zram_devops = {
700 .swap_slot_free_notify = zram_slot_free_notify,
701 .owner = THIS_MODULE
702};
703
704static int create_device(struct zram *zram, int device_id)
705{
706 int ret = 0;
707
708 init_rwsem(&zram->lock);
709 init_rwsem(&zram->init_lock);
710 spin_lock_init(&zram->stat64_lock);
711
712 zram->queue = blk_alloc_queue(GFP_KERNEL);
713 if (!zram->queue) {
714 pr_err("Error allocating disk queue for device %d\n",
715 device_id);
716 ret = -ENOMEM;
717 goto out;
718 }
719
720 blk_queue_make_request(zram->queue, zram_make_request);
721 zram->queue->queuedata = zram;
722
723 /* gendisk structure */
724 zram->disk = alloc_disk(1);
725 if (!zram->disk) {
726 blk_cleanup_queue(zram->queue);
727 pr_warning("Error allocating disk structure for device %d\n",
728 device_id);
729 ret = -ENOMEM;
730 goto out;
731 }
732
733 zram->disk->major = zram_major;
734 zram->disk->first_minor = device_id;
735 zram->disk->fops = &zram_devops;
736 zram->disk->queue = zram->queue;
737 zram->disk->private_data = zram;
738 snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
739
740 /* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
741 set_capacity(zram->disk, 0);
742
743 /*
744 * To ensure that we always get PAGE_SIZE aligned
745 * and n*PAGE_SIZED sized I/O requests.
746 */
747 blk_queue_physical_block_size(zram->disk->queue, PAGE_SIZE);
748 blk_queue_logical_block_size(zram->disk->queue,
749 ZRAM_LOGICAL_BLOCK_SIZE);
750 blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
751 blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
752
753 add_disk(zram->disk);
754
755 ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj,
756 &zram_disk_attr_group);
757 if (ret < 0) {
758 pr_warning("Error creating sysfs group");
759 goto out;
760 }
761
762 zram->init_done = 0;
763
764out:
765 return ret;
766}
767
768static void destroy_device(struct zram *zram)
769{
770 sysfs_remove_group(&disk_to_dev(zram->disk)->kobj,
771 &zram_disk_attr_group);
772
773 if (zram->disk) {
774 del_gendisk(zram->disk);
775 put_disk(zram->disk);
776 }
777
778 if (zram->queue)
779 blk_cleanup_queue(zram->queue);
780}
781
782unsigned int zram_get_num_devices(void)
783{
784 return num_devices;
785}
786
787static int __init zram_init(void)
788{
789 int ret, dev_id;
790
791 if (num_devices > max_num_devices) {
792 pr_warning("Invalid value for num_devices: %u\n",
793 num_devices);
794 ret = -EINVAL;
795 goto out;
796 }
797
798 zram_major = register_blkdev(0, "zram");
799 if (zram_major <= 0) {
800 pr_warning("Unable to get major number\n");
801 ret = -EBUSY;
802 goto out;
803 }
804
805 if (!num_devices) {
806 pr_info("num_devices not specified. Using default: 1\n");
807 num_devices = 1;
808 }
809
810 /* Allocate the device array and initialize each one */
811 pr_info("Creating %u devices ...\n", num_devices);
812 zram_devices = kzalloc(num_devices * sizeof(struct zram), GFP_KERNEL);
813 if (!zram_devices) {
814 ret = -ENOMEM;
815 goto unregister;
816 }
817
818 for (dev_id = 0; dev_id < num_devices; dev_id++) {
819 ret = create_device(&zram_devices[dev_id], dev_id);
820 if (ret)
821 goto free_devices;
822 }
823
824 return 0;
825
826free_devices:
827 while (dev_id)
828 destroy_device(&zram_devices[--dev_id]);
829 kfree(zram_devices);
830unregister:
831 unregister_blkdev(zram_major, "zram");
832out:
833 return ret;
834}
835
836static void __exit zram_exit(void)
837{
838 int i;
839 struct zram *zram;
840
841 for (i = 0; i < num_devices; i++) {
842 zram = &zram_devices[i];
843
844 destroy_device(zram);
845 if (zram->init_done)
846 zram_reset_device(zram);
847 }
848
849 unregister_blkdev(zram_major, "zram");
850
851 kfree(zram_devices);
852 pr_debug("Cleanup done!\n");
853}
854
855module_param(num_devices, uint, 0);
856MODULE_PARM_DESC(num_devices, "Number of zram devices");
857
858module_init(zram_init);
859module_exit(zram_exit);
860
861MODULE_LICENSE("Dual BSD/GPL");
862MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
863MODULE_DESCRIPTION("Compressed RAM Block Device");