1	/*
2	* Compressed RAM block device
3	*
4	* Copyright (C) 2008, 2009, 2010 Nitin Gupta
5	* 2012, 2013 Minchan Kim
6	*
7	* This code is released using a dual license strategy: BSD/GPL
8	* You can choose the licence that better fits your requirements.
9	*
10	* Released under the terms of 3-clause BSD License
11	* Released under the terms of GNU General Public License Version 2.0
12	*
13	*/
14
15	#define KMSG_COMPONENT "zram"
16	#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
17
18	#include <linux/module.h>
19	#include <linux/kernel.h>
20	#include <linux/bio.h>
21	#include <linux/bitops.h>
22	#include <linux/blkdev.h>
23	#include <linux/buffer_head.h>
24	#include <linux/device.h>
25	#include <linux/highmem.h>
26	#include <linux/slab.h>
27	#include <linux/backing-dev.h>
28	#include <linux/string.h>
29	#include <linux/vmalloc.h>
30	#include <linux/err.h>
31	#include <linux/idr.h>
32	#include <linux/sysfs.h>
33	#include <linux/debugfs.h>
34	#include <linux/cpuhotplug.h>
35	#include <linux/part_stat.h>
36
37	#include "zram_drv.h"
38
39	static DEFINE_IDR(zram_index_idr);
40	/* idr index must be protected */
41	static DEFINE_MUTEX(zram_index_mutex);
42
43	static int zram_major;
44	static const char *default_compressor = CONFIG_ZRAM_DEF_COMP;
45
46	/* Module params (documentation at end) */
47	static unsigned int num_devices = 1;
48	/*
49	* Pages that compress to sizes equals or greater than this are stored
50	* uncompressed in memory.
51	*/
52	static size_t huge_class_size;
53
54	static const struct block_device_operations zram_devops;
55
56	static void zram_free_page(struct zram *zram, size_t index);
57	static int zram_read_page(struct zram *zram, struct page *page, u32 index,
58	struct bio *parent);
59
60	static int zram_slot_trylock(struct zram *zram, u32 index)
61	{
62	return bit_spin_trylock(bitnum: ZRAM_LOCK, addr: &zram->table[index].flags);
63	}
64
65	static void zram_slot_lock(struct zram *zram, u32 index)
66	{
67	bit_spin_lock(bitnum: ZRAM_LOCK, addr: &zram->table[index].flags);
68	}
69
70	static void zram_slot_unlock(struct zram *zram, u32 index)
71	{
72	bit_spin_unlock(bitnum: ZRAM_LOCK, addr: &zram->table[index].flags);
73	}
74
75	static inline bool init_done(struct zram *zram)
76	{
77	return zram->disksize;
78	}
79
80	static inline struct zram *dev_to_zram(struct device *dev)
81	{
82	return (struct zram *)dev_to_disk(dev)->private_data;
83	}
84
85	static unsigned long zram_get_handle(struct zram *zram, u32 index)
86	{
87	return zram->table[index].handle;
88	}
89
90	static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle)
91	{
92	zram->table[index].handle = handle;
93	}
94
95	/* flag operations require table entry bit_spin_lock() being held */
96	static bool zram_test_flag(struct zram *zram, u32 index,
97	enum zram_pageflags flag)
98	{
99	return zram->table[index].flags & BIT(flag);
100	}
101
102	static void zram_set_flag(struct zram *zram, u32 index,
103	enum zram_pageflags flag)
104	{
105	zram->table[index].flags |= BIT(flag);
106	}
107
108	static void zram_clear_flag(struct zram *zram, u32 index,
109	enum zram_pageflags flag)
110	{
111	zram->table[index].flags &= ~BIT(flag);
112	}
113
114	static inline void zram_set_element(struct zram *zram, u32 index,
115	unsigned long element)
116	{
117	zram->table[index].element = element;
118	}
119
120	static unsigned long zram_get_element(struct zram *zram, u32 index)
121	{
122	return zram->table[index].element;
123	}
124
125	static size_t zram_get_obj_size(struct zram *zram, u32 index)
126	{
127	return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
128	}
129
130	static void zram_set_obj_size(struct zram *zram,
131	u32 index, size_t size)
132	{
133	unsigned long flags = zram->table[index].flags >> ZRAM_FLAG_SHIFT;
134
135	zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size;
136	}
137
138	static inline bool zram_allocated(struct zram *zram, u32 index)
139	{
140	return zram_get_obj_size(zram, index) ||
141	zram_test_flag(zram, index, flag: ZRAM_SAME) ||
142	zram_test_flag(zram, index, flag: ZRAM_WB);
143	}
144
145	#if PAGE_SIZE != 4096
146	static inline bool is_partial_io(struct bio_vec *bvec)
147	{
148	return bvec->bv_len != PAGE_SIZE;
149	}
150	#define ZRAM_PARTIAL_IO 1
151	#else
152	static inline bool is_partial_io(struct bio_vec *bvec)
153	{
154	return false;
155	}
156	#endif
157
158	static inline void zram_set_priority(struct zram *zram, u32 index, u32 prio)
159	{
160	prio &= ZRAM_COMP_PRIORITY_MASK;
161	/*
162	* Clear previous priority value first, in case if we recompress
163	* further an already recompressed page
164	*/
165	zram->table[index].flags &= ~(ZRAM_COMP_PRIORITY_MASK <<
166	ZRAM_COMP_PRIORITY_BIT1);
167	zram->table[index].flags |= (prio << ZRAM_COMP_PRIORITY_BIT1);
168	}
169
170	static inline u32 zram_get_priority(struct zram *zram, u32 index)
171	{
172	u32 prio = zram->table[index].flags >> ZRAM_COMP_PRIORITY_BIT1;
173
174	return prio & ZRAM_COMP_PRIORITY_MASK;
175	}
176
177	static void zram_accessed(struct zram *zram, u32 index)
178	{
179	zram_clear_flag(zram, index, flag: ZRAM_IDLE);
180	#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
181	zram->table[index].ac_time = ktime_get_boottime();
182	#endif
183	}
184
185	static inline void update_used_max(struct zram *zram,
186	const unsigned long pages)
187	{
188	unsigned long cur_max = atomic_long_read(v: &zram->stats.max_used_pages);
189
190	do {
191	if (cur_max >= pages)
192	return;
193	} while (!atomic_long_try_cmpxchg(v: &zram->stats.max_used_pages,
194	old: &cur_max, new: pages));
195	}
196
197	static inline void zram_fill_page(void *ptr, unsigned long len,
198	unsigned long value)
199	{
200	WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long)));
201	memset_l(p: ptr, v: value, n: len / sizeof(unsigned long));
202	}
203
204	static bool page_same_filled(void *ptr, unsigned long *element)
205	{
206	unsigned long *page;
207	unsigned long val;
208	unsigned int pos, last_pos = PAGE_SIZE / sizeof(*page) - 1;
209
210	page = (unsigned long *)ptr;
211	val = page[0];
212
213	if (val != page[last_pos])
214	return false;
215
216	for (pos = 1; pos < last_pos; pos++) {
217	if (val != page[pos])
218	return false;
219	}
220
221	*element = val;
222
223	return true;
224	}
225
226	static ssize_t initstate_show(struct device *dev,
227	struct device_attribute *attr, char *buf)
228	{
229	u32 val;
230	struct zram *zram = dev_to_zram(dev);
231
232	down_read(sem: &zram->init_lock);
233	val = init_done(zram);
234	up_read(sem: &zram->init_lock);
235
236	return scnprintf(buf, PAGE_SIZE, fmt: "%u\n", val);
237	}
238
239	static ssize_t disksize_show(struct device *dev,
240	struct device_attribute *attr, char *buf)
241	{
242	struct zram *zram = dev_to_zram(dev);
243
244	return scnprintf(buf, PAGE_SIZE, fmt: "%llu\n", zram->disksize);
245	}
246
247	static ssize_t mem_limit_store(struct device *dev,
248	struct device_attribute *attr, const char *buf, size_t len)
249	{
250	u64 limit;
251	char *tmp;
252	struct zram *zram = dev_to_zram(dev);
253
254	limit = memparse(ptr: buf, retptr: &tmp);
255	if (buf == tmp) /* no chars parsed, invalid input */
256	return -EINVAL;
257
258	down_write(sem: &zram->init_lock);
259	zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
260	up_write(sem: &zram->init_lock);
261
262	return len;
263	}
264
265	static ssize_t mem_used_max_store(struct device *dev,
266	struct device_attribute *attr, const char *buf, size_t len)
267	{
268	int err;
269	unsigned long val;
270	struct zram *zram = dev_to_zram(dev);
271
272	err = kstrtoul(s: buf, base: 10, res: &val);
273	if (err || val != 0)
274	return -EINVAL;
275
276	down_read(sem: &zram->init_lock);
277	if (init_done(zram)) {
278	atomic_long_set(v: &zram->stats.max_used_pages,
279	i: zs_get_total_pages(pool: zram->mem_pool));
280	}
281	up_read(sem: &zram->init_lock);
282
283	return len;
284	}
285
286	/*
287	* Mark all pages which are older than or equal to cutoff as IDLE.
288	* Callers should hold the zram init lock in read mode
289	*/
290	static void mark_idle(struct zram *zram, ktime_t cutoff)
291	{
292	int is_idle = 1;
293	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
294	int index;
295
296	for (index = 0; index < nr_pages; index++) {
297	/*
298	* Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race.
299	* See the comment in writeback_store.
300	*/
301	zram_slot_lock(zram, index);
302	if (zram_allocated(zram, index) &&
303	!zram_test_flag(zram, index, flag: ZRAM_UNDER_WB)) {
304	#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
305	is_idle = !cutoff || ktime_after(cmp1: cutoff,
306	cmp2: zram->table[index].ac_time);
307	#endif
308	if (is_idle)
309	zram_set_flag(zram, index, flag: ZRAM_IDLE);
310	}
311	zram_slot_unlock(zram, index);
312	}
313	}
314
315	static ssize_t idle_store(struct device *dev,
316	struct device_attribute *attr, const char *buf, size_t len)
317	{
318	struct zram *zram = dev_to_zram(dev);
319	ktime_t cutoff_time = 0;
320	ssize_t rv = -EINVAL;
321
322	if (!sysfs_streq(s1: buf, s2: "all")) {
323	/*
324	* If it did not parse as 'all' try to treat it as an integer
325	* when we have memory tracking enabled.
326	*/
327	u64 age_sec;
328
329	if (IS_ENABLED(CONFIG_ZRAM_TRACK_ENTRY_ACTIME) && !kstrtoull(s: buf, base: 0, res: &age_sec))
330	cutoff_time = ktime_sub(ktime_get_boottime(),
331	ns_to_ktime(age_sec * NSEC_PER_SEC));
332	else
333	goto out;
334	}
335
336	down_read(sem: &zram->init_lock);
337	if (!init_done(zram))
338	goto out_unlock;
339
340	/*
341	* A cutoff_time of 0 marks everything as idle, this is the
342	* "all" behavior.
343	*/
344	mark_idle(zram, cutoff: cutoff_time);
345	rv = len;
346
347	out_unlock:
348	up_read(sem: &zram->init_lock);
349	out:
350	return rv;
351	}
352
353	#ifdef CONFIG_ZRAM_WRITEBACK
354	static ssize_t writeback_limit_enable_store(struct device *dev,
355	struct device_attribute *attr, const char *buf, size_t len)
356	{
357	struct zram *zram = dev_to_zram(dev);
358	u64 val;
359	ssize_t ret = -EINVAL;
360
361	if (kstrtoull(s: buf, base: 10, res: &val))
362	return ret;
363
364	down_read(sem: &zram->init_lock);
365	spin_lock(lock: &zram->wb_limit_lock);
366	zram->wb_limit_enable = val;
367	spin_unlock(lock: &zram->wb_limit_lock);
368	up_read(sem: &zram->init_lock);
369	ret = len;
370
371	return ret;
372	}
373
374	static ssize_t writeback_limit_enable_show(struct device *dev,
375	struct device_attribute *attr, char *buf)
376	{
377	bool val;
378	struct zram *zram = dev_to_zram(dev);
379
380	down_read(sem: &zram->init_lock);
381	spin_lock(lock: &zram->wb_limit_lock);
382	val = zram->wb_limit_enable;
383	spin_unlock(lock: &zram->wb_limit_lock);
384	up_read(sem: &zram->init_lock);
385
386	return scnprintf(buf, PAGE_SIZE, fmt: "%d\n", val);
387	}
388
389	static ssize_t writeback_limit_store(struct device *dev,
390	struct device_attribute *attr, const char *buf, size_t len)
391	{
392	struct zram *zram = dev_to_zram(dev);
393	u64 val;
394	ssize_t ret = -EINVAL;
395
396	if (kstrtoull(s: buf, base: 10, res: &val))
397	return ret;
398
399	down_read(sem: &zram->init_lock);
400	spin_lock(lock: &zram->wb_limit_lock);
401	zram->bd_wb_limit = val;
402	spin_unlock(lock: &zram->wb_limit_lock);
403	up_read(sem: &zram->init_lock);
404	ret = len;
405
406	return ret;
407	}
408
409	static ssize_t writeback_limit_show(struct device *dev,
410	struct device_attribute *attr, char *buf)
411	{
412	u64 val;
413	struct zram *zram = dev_to_zram(dev);
414
415	down_read(sem: &zram->init_lock);
416	spin_lock(lock: &zram->wb_limit_lock);
417	val = zram->bd_wb_limit;
418	spin_unlock(lock: &zram->wb_limit_lock);
419	up_read(sem: &zram->init_lock);
420
421	return scnprintf(buf, PAGE_SIZE, fmt: "%llu\n", val);
422	}
423
424	static void reset_bdev(struct zram *zram)
425	{
426	if (!zram->backing_dev)
427	return;
428
429	fput(zram->bdev_file);
430	/* hope filp_close flush all of IO */
431	filp_close(zram->backing_dev, NULL);
432	zram->backing_dev = NULL;
433	zram->bdev_file = NULL;
434	zram->disk->fops = &zram_devops;
435	kvfree(addr: zram->bitmap);
436	zram->bitmap = NULL;
437	}
438
439	static ssize_t backing_dev_show(struct device *dev,
440	struct device_attribute *attr, char *buf)
441	{
442	struct file *file;
443	struct zram *zram = dev_to_zram(dev);
444	char *p;
445	ssize_t ret;
446
447	down_read(sem: &zram->init_lock);
448	file = zram->backing_dev;
449	if (!file) {
450	memcpy(buf, "none\n", 5);
451	up_read(sem: &zram->init_lock);
452	return 5;
453	}
454
455	p = file_path(file, buf, PAGE_SIZE - 1);
456	if (IS_ERR(ptr: p)) {
457	ret = PTR_ERR(ptr: p);
458	goto out;
459	}
460
461	ret = strlen(p);
462	memmove(buf, p, ret);
463	buf[ret++] = '\n';
464	out:
465	up_read(sem: &zram->init_lock);
466	return ret;
467	}
468
469	static ssize_t backing_dev_store(struct device *dev,
470	struct device_attribute *attr, const char *buf, size_t len)
471	{
472	char *file_name;
473	size_t sz;
474	struct file *backing_dev = NULL;
475	struct inode *inode;
476	struct address_space *mapping;
477	unsigned int bitmap_sz;
478	unsigned long nr_pages, *bitmap = NULL;
479	struct file *bdev_file = NULL;
480	int err;
481	struct zram *zram = dev_to_zram(dev);
482
483	file_name = kmalloc(PATH_MAX, GFP_KERNEL);
484	if (!file_name)
485	return -ENOMEM;
486
487	down_write(sem: &zram->init_lock);
488	if (init_done(zram)) {
489	pr_info("Can't setup backing device for initialized device\n");
490	err = -EBUSY;
491	goto out;
492	}
493
494	strscpy(file_name, buf, PATH_MAX);
495	/* ignore trailing newline */
496	sz = strlen(file_name);
497	if (sz > 0 && file_name[sz - 1] == '\n')
498	file_name[sz - 1] = 0x00;
499
500	backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);
501	if (IS_ERR(ptr: backing_dev)) {
502	err = PTR_ERR(ptr: backing_dev);
503	backing_dev = NULL;
504	goto out;
505	}
506
507	mapping = backing_dev->f_mapping;
508	inode = mapping->host;
509
510	/* Support only block device in this moment */
511	if (!S_ISBLK(inode->i_mode)) {
512	err = -ENOTBLK;
513	goto out;
514	}
515
516	bdev_file = bdev_file_open_by_dev(dev: inode->i_rdev,
517	BLK_OPEN_READ | BLK_OPEN_WRITE, holder: zram, NULL);
518	if (IS_ERR(ptr: bdev_file)) {
519	err = PTR_ERR(ptr: bdev_file);
520	bdev_file = NULL;
521	goto out;
522	}
523
524	nr_pages = i_size_read(inode) >> PAGE_SHIFT;
525	bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long);
526	bitmap = kvzalloc(size: bitmap_sz, GFP_KERNEL);
527	if (!bitmap) {
528	err = -ENOMEM;
529	goto out;
530	}
531
532	reset_bdev(zram);
533
534	zram->bdev_file = bdev_file;
535	zram->backing_dev = backing_dev;
536	zram->bitmap = bitmap;
537	zram->nr_pages = nr_pages;
538	up_write(sem: &zram->init_lock);
539
540	pr_info("setup backing device %s\n", file_name);
541	kfree(objp: file_name);
542
543	return len;
544	out:
545	kvfree(addr: bitmap);
546
547	if (bdev_file)
548	fput(bdev_file);
549
550	if (backing_dev)
551	filp_close(backing_dev, NULL);
552
553	up_write(sem: &zram->init_lock);
554
555	kfree(objp: file_name);
556
557	return err;
558	}
559
560	static unsigned long alloc_block_bdev(struct zram *zram)
561	{
562	unsigned long blk_idx = 1;
563	retry:
564	/* skip 0 bit to confuse zram.handle = 0 */
565	blk_idx = find_next_zero_bit(addr: zram->bitmap, size: zram->nr_pages, offset: blk_idx);
566	if (blk_idx == zram->nr_pages)
567	return 0;
568
569	if (test_and_set_bit(nr: blk_idx, addr: zram->bitmap))
570	goto retry;
571
572	atomic64_inc(v: &zram->stats.bd_count);
573	return blk_idx;
574	}
575
576	static void free_block_bdev(struct zram *zram, unsigned long blk_idx)
577	{
578	int was_set;
579
580	was_set = test_and_clear_bit(nr: blk_idx, addr: zram->bitmap);
581	WARN_ON_ONCE(!was_set);
582	atomic64_dec(v: &zram->stats.bd_count);
583	}
584
585	static void read_from_bdev_async(struct zram *zram, struct page *page,
586	unsigned long entry, struct bio *parent)
587	{
588	struct bio *bio;
589
590	bio = bio_alloc(bdev: file_bdev(bdev_file: zram->bdev_file), nr_vecs: 1, opf: parent->bi_opf, GFP_NOIO);
591	bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9);
592	__bio_add_page(bio, page, PAGE_SIZE, off: 0);
593	bio_chain(bio, parent);
594	submit_bio(bio);
595	}
596
597	#define PAGE_WB_SIG "page_index="
598
599	#define PAGE_WRITEBACK 0
600	#define HUGE_WRITEBACK (1<<0)
601	#define IDLE_WRITEBACK (1<<1)
602	#define INCOMPRESSIBLE_WRITEBACK (1<<2)
603
604	static ssize_t writeback_store(struct device *dev,
605	struct device_attribute *attr, const char *buf, size_t len)
606	{
607	struct zram *zram = dev_to_zram(dev);
608	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
609	unsigned long index = 0;
610	struct bio bio;
611	struct bio_vec bio_vec;
612	struct page *page;
613	ssize_t ret = len;
614	int mode, err;
615	unsigned long blk_idx = 0;
616
617	if (sysfs_streq(s1: buf, s2: "idle"))
618	mode = IDLE_WRITEBACK;
619	else if (sysfs_streq(s1: buf, s2: "huge"))
620	mode = HUGE_WRITEBACK;
621	else if (sysfs_streq(s1: buf, s2: "huge_idle"))
622	mode = IDLE_WRITEBACK | HUGE_WRITEBACK;
623	else if (sysfs_streq(s1: buf, s2: "incompressible"))
624	mode = INCOMPRESSIBLE_WRITEBACK;
625	else {
626	if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1))
627	return -EINVAL;
628
629	if (kstrtol(s: buf + sizeof(PAGE_WB_SIG) - 1, base: 10, res: &index) ||
630	index >= nr_pages)
631	return -EINVAL;
632
633	nr_pages = 1;
634	mode = PAGE_WRITEBACK;
635	}
636
637	down_read(sem: &zram->init_lock);
638	if (!init_done(zram)) {
639	ret = -EINVAL;
640	goto release_init_lock;
641	}
642
643	if (!zram->backing_dev) {
644	ret = -ENODEV;
645	goto release_init_lock;
646	}
647
648	page = alloc_page(GFP_KERNEL);
649	if (!page) {
650	ret = -ENOMEM;
651	goto release_init_lock;
652	}
653
654	for (; nr_pages != 0; index++, nr_pages--) {
655	spin_lock(lock: &zram->wb_limit_lock);
656	if (zram->wb_limit_enable && !zram->bd_wb_limit) {
657	spin_unlock(lock: &zram->wb_limit_lock);
658	ret = -EIO;
659	break;
660	}
661	spin_unlock(lock: &zram->wb_limit_lock);
662
663	if (!blk_idx) {
664	blk_idx = alloc_block_bdev(zram);
665	if (!blk_idx) {
666	ret = -ENOSPC;
667	break;
668	}
669	}
670
671	zram_slot_lock(zram, index);
672	if (!zram_allocated(zram, index))
673	goto next;
674
675	if (zram_test_flag(zram, index, flag: ZRAM_WB) ||
676	zram_test_flag(zram, index, flag: ZRAM_SAME) ||
677	zram_test_flag(zram, index, flag: ZRAM_UNDER_WB))
678	goto next;
679
680	if (mode & IDLE_WRITEBACK &&
681	!zram_test_flag(zram, index, flag: ZRAM_IDLE))
682	goto next;
683	if (mode & HUGE_WRITEBACK &&
684	!zram_test_flag(zram, index, flag: ZRAM_HUGE))
685	goto next;
686	if (mode & INCOMPRESSIBLE_WRITEBACK &&
687	!zram_test_flag(zram, index, flag: ZRAM_INCOMPRESSIBLE))
688	goto next;
689
690	/*
691	* Clearing ZRAM_UNDER_WB is duty of caller.
692	* IOW, zram_free_page never clear it.
693	*/
694	zram_set_flag(zram, index, flag: ZRAM_UNDER_WB);
695	/* Need for hugepage writeback racing */
696	zram_set_flag(zram, index, flag: ZRAM_IDLE);
697	zram_slot_unlock(zram, index);
698	if (zram_read_page(zram, page, index, NULL)) {
699	zram_slot_lock(zram, index);
700	zram_clear_flag(zram, index, flag: ZRAM_UNDER_WB);
701	zram_clear_flag(zram, index, flag: ZRAM_IDLE);
702	zram_slot_unlock(zram, index);
703	continue;
704	}
705
706	bio_init(bio: &bio, bdev: file_bdev(bdev_file: zram->bdev_file), table: &bio_vec, max_vecs: 1,
707	opf: REQ_OP_WRITE | REQ_SYNC);
708	bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9);
709	__bio_add_page(bio: &bio, page, PAGE_SIZE, off: 0);
710
711	/*
712	* XXX: A single page IO would be inefficient for write
713	* but it would be not bad as starter.
714	*/
715	err = submit_bio_wait(bio: &bio);
716	if (err) {
717	zram_slot_lock(zram, index);
718	zram_clear_flag(zram, index, flag: ZRAM_UNDER_WB);
719	zram_clear_flag(zram, index, flag: ZRAM_IDLE);
720	zram_slot_unlock(zram, index);
721	/*
722	* BIO errors are not fatal, we continue and simply
723	* attempt to writeback the remaining objects (pages).
724	* At the same time we need to signal user-space that
725	* some writes (at least one, but also could be all of
726	* them) were not successful and we do so by returning
727	* the most recent BIO error.
728	*/
729	ret = err;
730	continue;
731	}
732
733	atomic64_inc(v: &zram->stats.bd_writes);
734	/*
735	* We released zram_slot_lock so need to check if the slot was
736	* changed. If there is freeing for the slot, we can catch it
737	* easily by zram_allocated.
738	* A subtle case is the slot is freed/reallocated/marked as
739	* ZRAM_IDLE again. To close the race, idle_store doesn't
740	* mark ZRAM_IDLE once it found the slot was ZRAM_UNDER_WB.
741	* Thus, we could close the race by checking ZRAM_IDLE bit.
742	*/
743	zram_slot_lock(zram, index);
744	if (!zram_allocated(zram, index) ||
745	!zram_test_flag(zram, index, flag: ZRAM_IDLE)) {
746	zram_clear_flag(zram, index, flag: ZRAM_UNDER_WB);
747	zram_clear_flag(zram, index, flag: ZRAM_IDLE);
748	goto next;
749	}
750
751	zram_free_page(zram, index);
752	zram_clear_flag(zram, index, flag: ZRAM_UNDER_WB);
753	zram_set_flag(zram, index, flag: ZRAM_WB);
754	zram_set_element(zram, index, element: blk_idx);
755	blk_idx = 0;
756	atomic64_inc(v: &zram->stats.pages_stored);
757	spin_lock(lock: &zram->wb_limit_lock);
758	if (zram->wb_limit_enable && zram->bd_wb_limit > 0)
759	zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12);
760	spin_unlock(lock: &zram->wb_limit_lock);
761	next:
762	zram_slot_unlock(zram, index);
763	}
764
765	if (blk_idx)
766	free_block_bdev(zram, blk_idx);
767	__free_page(page);
768	release_init_lock:
769	up_read(sem: &zram->init_lock);
770
771	return ret;
772	}
773
774	struct zram_work {
775	struct work_struct work;
776	struct zram *zram;
777	unsigned long entry;
778	struct page *page;
779	int error;
780	};
781
782	static void zram_sync_read(struct work_struct *work)
783	{
784	struct zram_work *zw = container_of(work, struct zram_work, work);
785	struct bio_vec bv;
786	struct bio bio;
787
788	bio_init(bio: &bio, bdev: file_bdev(bdev_file: zw->zram->bdev_file), table: &bv, max_vecs: 1, opf: REQ_OP_READ);
789	bio.bi_iter.bi_sector = zw->entry * (PAGE_SIZE >> 9);
790	__bio_add_page(bio: &bio, page: zw->page, PAGE_SIZE, off: 0);
791	zw->error = submit_bio_wait(bio: &bio);
792	}
793
794	/*
795	* Block layer want one ->submit_bio to be active at a time, so if we use
796	* chained IO with parent IO in same context, it's a deadlock. To avoid that,
797	* use a worker thread context.
798	*/
799	static int read_from_bdev_sync(struct zram *zram, struct page *page,
800	unsigned long entry)
801	{
802	struct zram_work work;
803
804	work.page = page;
805	work.zram = zram;
806	work.entry = entry;
807
808	INIT_WORK_ONSTACK(&work.work, zram_sync_read);
809	queue_work(wq: system_unbound_wq, work: &work.work);
810	flush_work(work: &work.work);
811	destroy_work_on_stack(work: &work.work);
812
813	return work.error;
814	}
815
816	static int read_from_bdev(struct zram *zram, struct page *page,
817	unsigned long entry, struct bio *parent)
818	{
819	atomic64_inc(v: &zram->stats.bd_reads);
820	if (!parent) {
821	if (WARN_ON_ONCE(!IS_ENABLED(ZRAM_PARTIAL_IO)))
822	return -EIO;
823	return read_from_bdev_sync(zram, page, entry);
824	}
825	read_from_bdev_async(zram, page, entry, parent);
826	return 0;
827	}
828	#else
829	static inline void reset_bdev(struct zram *zram) {};
830	static int read_from_bdev(struct zram *zram, struct page *page,
831	unsigned long entry, struct bio *parent)
832	{
833	return -EIO;
834	}
835
836	static void free_block_bdev(struct zram *zram, unsigned long blk_idx) {};
837	#endif
838
839	#ifdef CONFIG_ZRAM_MEMORY_TRACKING
840
841	static struct dentry *zram_debugfs_root;
842
843	static void zram_debugfs_create(void)
844	{
845	zram_debugfs_root = debugfs_create_dir(name: "zram", NULL);
846	}
847
848	static void zram_debugfs_destroy(void)
849	{
850	debugfs_remove_recursive(dentry: zram_debugfs_root);
851	}
852
853	static ssize_t read_block_state(struct file *file, char __user *buf,
854	size_t count, loff_t *ppos)
855	{
856	char *kbuf;
857	ssize_t index, written = 0;
858	struct zram *zram = file->private_data;
859	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
860	struct timespec64 ts;
861
862	kbuf = kvmalloc(size: count, GFP_KERNEL);
863	if (!kbuf)
864	return -ENOMEM;
865
866	down_read(sem: &zram->init_lock);
867	if (!init_done(zram)) {
868	up_read(sem: &zram->init_lock);
869	kvfree(addr: kbuf);
870	return -EINVAL;
871	}
872
873	for (index = *ppos; index < nr_pages; index++) {
874	int copied;
875
876	zram_slot_lock(zram, index);
877	if (!zram_allocated(zram, index))
878	goto next;
879
880	ts = ktime_to_timespec64(zram->table[index].ac_time);
881	copied = snprintf(buf: kbuf + written, size: count,
882	fmt: "%12zd %12lld.%06lu %c%c%c%c%c%c\n",
883	index, (s64)ts.tv_sec,
884	ts.tv_nsec / NSEC_PER_USEC,
885	zram_test_flag(zram, index, flag: ZRAM_SAME) ? 's' : '.',
886	zram_test_flag(zram, index, flag: ZRAM_WB) ? 'w' : '.',
887	zram_test_flag(zram, index, flag: ZRAM_HUGE) ? 'h' : '.',
888	zram_test_flag(zram, index, flag: ZRAM_IDLE) ? 'i' : '.',
889	zram_get_priority(zram, index) ? 'r' : '.',
890	zram_test_flag(zram, index,
891	flag: ZRAM_INCOMPRESSIBLE) ? 'n' : '.');
892
893	if (count <= copied) {
894	zram_slot_unlock(zram, index);
895	break;
896	}
897	written += copied;
898	count -= copied;
899	next:
900	zram_slot_unlock(zram, index);
901	*ppos += 1;
902	}
903
904	up_read(sem: &zram->init_lock);
905	if (copy_to_user(to: buf, from: kbuf, n: written))
906	written = -EFAULT;
907	kvfree(addr: kbuf);
908
909	return written;
910	}
911
912	static const struct file_operations proc_zram_block_state_op = {
913	.open = simple_open,
914	.read = read_block_state,
915	.llseek = default_llseek,
916	};
917
918	static void zram_debugfs_register(struct zram *zram)
919	{
920	if (!zram_debugfs_root)
921	return;
922
923	zram->debugfs_dir = debugfs_create_dir(name: zram->disk->disk_name,
924	parent: zram_debugfs_root);
925	debugfs_create_file(name: "block_state", mode: 0400, parent: zram->debugfs_dir,
926	data: zram, fops: &proc_zram_block_state_op);
927	}
928
929	static void zram_debugfs_unregister(struct zram *zram)
930	{
931	debugfs_remove_recursive(dentry: zram->debugfs_dir);
932	}
933	#else
934	static void zram_debugfs_create(void) {};
935	static void zram_debugfs_destroy(void) {};
936	static void zram_debugfs_register(struct zram *zram) {};
937	static void zram_debugfs_unregister(struct zram *zram) {};
938	#endif
939
940	/*
941	* We switched to per-cpu streams and this attr is not needed anymore.
942	* However, we will keep it around for some time, because:
943	* a) we may revert per-cpu streams in the future
944	* b) it's visible to user space and we need to follow our 2 years
945	* retirement rule; but we already have a number of 'soon to be
946	* altered' attrs, so max_comp_streams need to wait for the next
947	* layoff cycle.
948	*/
949	static ssize_t max_comp_streams_show(struct device *dev,
950	struct device_attribute *attr, char *buf)
951	{
952	return scnprintf(buf, PAGE_SIZE, fmt: "%d\n", num_online_cpus());
953	}
954
955	static ssize_t max_comp_streams_store(struct device *dev,
956	struct device_attribute *attr, const char *buf, size_t len)
957	{
958	return len;
959	}
960
961	static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg)
962	{
963	/* Do not free statically defined compression algorithms */
964	if (zram->comp_algs[prio] != default_compressor)
965	kfree(objp: zram->comp_algs[prio]);
966
967	zram->comp_algs[prio] = alg;
968	}
969
970	static ssize_t __comp_algorithm_show(struct zram *zram, u32 prio, char *buf)
971	{
972	ssize_t sz;
973
974	down_read(sem: &zram->init_lock);
975	sz = zcomp_available_show(comp: zram->comp_algs[prio], buf);
976	up_read(sem: &zram->init_lock);
977
978	return sz;
979	}
980
981	static int __comp_algorithm_store(struct zram *zram, u32 prio, const char *buf)
982	{
983	char *compressor;
984	size_t sz;
985
986	sz = strlen(buf);
987	if (sz >= CRYPTO_MAX_ALG_NAME)
988	return -E2BIG;
989
990	compressor = kstrdup(s: buf, GFP_KERNEL);
991	if (!compressor)
992	return -ENOMEM;
993
994	/* ignore trailing newline */
995	if (sz > 0 && compressor[sz - 1] == '\n')
996	compressor[sz - 1] = 0x00;
997
998	if (!zcomp_available_algorithm(comp: compressor)) {
999	kfree(objp: compressor);
1000	return -EINVAL;
1001	}
1002
1003	down_write(sem: &zram->init_lock);
1004	if (init_done(zram)) {
1005	up_write(sem: &zram->init_lock);
1006	kfree(objp: compressor);
1007	pr_info("Can't change algorithm for initialized device\n");
1008	return -EBUSY;
1009	}
1010
1011	comp_algorithm_set(zram, prio, alg: compressor);
1012	up_write(sem: &zram->init_lock);
1013	return 0;
1014	}
1015
1016	static ssize_t comp_algorithm_show(struct device *dev,
1017	struct device_attribute *attr,
1018	char *buf)
1019	{
1020	struct zram *zram = dev_to_zram(dev);
1021
1022	return __comp_algorithm_show(zram, ZRAM_PRIMARY_COMP, buf);
1023	}
1024
1025	static ssize_t comp_algorithm_store(struct device *dev,
1026	struct device_attribute *attr,
1027	const char *buf,
1028	size_t len)
1029	{
1030	struct zram *zram = dev_to_zram(dev);
1031	int ret;
1032
1033	ret = __comp_algorithm_store(zram, ZRAM_PRIMARY_COMP, buf);
1034	return ret ? ret : len;
1035	}
1036
1037	#ifdef CONFIG_ZRAM_MULTI_COMP
1038	static ssize_t recomp_algorithm_show(struct device *dev,
1039	struct device_attribute *attr,
1040	char *buf)
1041	{
1042	struct zram *zram = dev_to_zram(dev);
1043	ssize_t sz = 0;
1044	u32 prio;
1045
1046	for (prio = ZRAM_SECONDARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {
1047	if (!zram->comp_algs[prio])
1048	continue;
1049
1050	sz += scnprintf(buf: buf + sz, PAGE_SIZE - sz - 2, fmt: "#%d: ", prio);
1051	sz += __comp_algorithm_show(zram, prio, buf: buf + sz);
1052	}
1053
1054	return sz;
1055	}
1056
1057	static ssize_t recomp_algorithm_store(struct device *dev,
1058	struct device_attribute *attr,
1059	const char *buf,
1060	size_t len)
1061	{
1062	struct zram *zram = dev_to_zram(dev);
1063	int prio = ZRAM_SECONDARY_COMP;
1064	char *args, *param, *val;
1065	char *alg = NULL;
1066	int ret;
1067
1068	args = skip_spaces(buf);
1069	while (*args) {
1070	args = next_arg(args, param: &param, val: &val);
1071
1072	if (!val || !*val)
1073	return -EINVAL;
1074
1075	if (!strcmp(param, "algo")) {
1076	alg = val;
1077	continue;
1078	}
1079
1080	if (!strcmp(param, "priority")) {
1081	ret = kstrtoint(s: val, base: 10, res: &prio);
1082	if (ret)
1083	return ret;
1084	continue;
1085	}
1086	}
1087
1088	if (!alg)
1089	return -EINVAL;
1090
1091	if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS)
1092	return -EINVAL;
1093
1094	ret = __comp_algorithm_store(zram, prio, buf: alg);
1095	return ret ? ret : len;
1096	}
1097	#endif
1098
1099	static ssize_t compact_store(struct device *dev,
1100	struct device_attribute *attr, const char *buf, size_t len)
1101	{
1102	struct zram *zram = dev_to_zram(dev);
1103
1104	down_read(sem: &zram->init_lock);
1105	if (!init_done(zram)) {
1106	up_read(sem: &zram->init_lock);
1107	return -EINVAL;
1108	}
1109
1110	zs_compact(pool: zram->mem_pool);
1111	up_read(sem: &zram->init_lock);
1112
1113	return len;
1114	}
1115
1116	static ssize_t io_stat_show(struct device *dev,
1117	struct device_attribute *attr, char *buf)
1118	{
1119	struct zram *zram = dev_to_zram(dev);
1120	ssize_t ret;
1121
1122	down_read(sem: &zram->init_lock);
1123	ret = scnprintf(buf, PAGE_SIZE,
1124	fmt: "%8llu %8llu 0 %8llu\n",
1125	(u64)atomic64_read(v: &zram->stats.failed_reads),
1126	(u64)atomic64_read(v: &zram->stats.failed_writes),
1127	(u64)atomic64_read(v: &zram->stats.notify_free));
1128	up_read(sem: &zram->init_lock);
1129
1130	return ret;
1131	}
1132
1133	static ssize_t mm_stat_show(struct device *dev,
1134	struct device_attribute *attr, char *buf)
1135	{
1136	struct zram *zram = dev_to_zram(dev);
1137	struct zs_pool_stats pool_stats;
1138	u64 orig_size, mem_used = 0;
1139	long max_used;
1140	ssize_t ret;
1141
1142	memset(&pool_stats, 0x00, sizeof(struct zs_pool_stats));
1143
1144	down_read(sem: &zram->init_lock);
1145	if (init_done(zram)) {
1146	mem_used = zs_get_total_pages(pool: zram->mem_pool);
1147	zs_pool_stats(pool: zram->mem_pool, stats: &pool_stats);
1148	}
1149
1150	orig_size = atomic64_read(v: &zram->stats.pages_stored);
1151	max_used = atomic_long_read(v: &zram->stats.max_used_pages);
1152
1153	ret = scnprintf(buf, PAGE_SIZE,
1154	fmt: "%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu %8llu\n",
1155	orig_size << PAGE_SHIFT,
1156	(u64)atomic64_read(v: &zram->stats.compr_data_size),
1157	mem_used << PAGE_SHIFT,
1158	zram->limit_pages << PAGE_SHIFT,
1159	max_used << PAGE_SHIFT,
1160	(u64)atomic64_read(v: &zram->stats.same_pages),
1161	atomic_long_read(v: &pool_stats.pages_compacted),
1162	(u64)atomic64_read(v: &zram->stats.huge_pages),
1163	(u64)atomic64_read(v: &zram->stats.huge_pages_since));
1164	up_read(sem: &zram->init_lock);
1165
1166	return ret;
1167	}
1168
1169	#ifdef CONFIG_ZRAM_WRITEBACK
1170	#define FOUR_K(x) ((x) * (1 << (PAGE_SHIFT - 12)))
1171	static ssize_t bd_stat_show(struct device *dev,
1172	struct device_attribute *attr, char *buf)
1173	{
1174	struct zram *zram = dev_to_zram(dev);
1175	ssize_t ret;
1176
1177	down_read(sem: &zram->init_lock);
1178	ret = scnprintf(buf, PAGE_SIZE,
1179	fmt: "%8llu %8llu %8llu\n",
1180	FOUR_K((u64)atomic64_read(&zram->stats.bd_count)),
1181	FOUR_K((u64)atomic64_read(&zram->stats.bd_reads)),
1182	FOUR_K((u64)atomic64_read(&zram->stats.bd_writes)));
1183	up_read(sem: &zram->init_lock);
1184
1185	return ret;
1186	}
1187	#endif
1188
1189	static ssize_t debug_stat_show(struct device *dev,
1190	struct device_attribute *attr, char *buf)
1191	{
1192	int version = 1;
1193	struct zram *zram = dev_to_zram(dev);
1194	ssize_t ret;
1195
1196	down_read(sem: &zram->init_lock);
1197	ret = scnprintf(buf, PAGE_SIZE,
1198	fmt: "version: %d\n%8llu %8llu\n",
1199	version,
1200	(u64)atomic64_read(v: &zram->stats.writestall),
1201	(u64)atomic64_read(v: &zram->stats.miss_free));
1202	up_read(sem: &zram->init_lock);
1203
1204	return ret;
1205	}
1206
1207	static DEVICE_ATTR_RO(io_stat);
1208	static DEVICE_ATTR_RO(mm_stat);
1209	#ifdef CONFIG_ZRAM_WRITEBACK
1210	static DEVICE_ATTR_RO(bd_stat);
1211	#endif
1212	static DEVICE_ATTR_RO(debug_stat);
1213
1214	static void zram_meta_free(struct zram *zram, u64 disksize)
1215	{
1216	size_t num_pages = disksize >> PAGE_SHIFT;
1217	size_t index;
1218
1219	/* Free all pages that are still in this zram device */
1220	for (index = 0; index < num_pages; index++)
1221	zram_free_page(zram, index);
1222
1223	zs_destroy_pool(pool: zram->mem_pool);
1224	vfree(addr: zram->table);
1225	}
1226
1227	static bool zram_meta_alloc(struct zram *zram, u64 disksize)
1228	{
1229	size_t num_pages;
1230
1231	num_pages = disksize >> PAGE_SHIFT;
1232	zram->table = vzalloc(array_size(num_pages, sizeof(*zram->table)));
1233	if (!zram->table)
1234	return false;
1235
1236	zram->mem_pool = zs_create_pool(name: zram->disk->disk_name);
1237	if (!zram->mem_pool) {
1238	vfree(addr: zram->table);
1239	return false;
1240	}
1241
1242	if (!huge_class_size)
1243	huge_class_size = zs_huge_class_size(pool: zram->mem_pool);
1244	return true;
1245	}
1246
1247	/*
1248	* To protect concurrent access to the same index entry,
1249	* caller should hold this table index entry's bit_spinlock to
1250	* indicate this index entry is accessing.
1251	*/
1252	static void zram_free_page(struct zram *zram, size_t index)
1253	{
1254	unsigned long handle;
1255
1256	#ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
1257	zram->table[index].ac_time = 0;
1258	#endif
1259	if (zram_test_flag(zram, index, flag: ZRAM_IDLE))
1260	zram_clear_flag(zram, index, flag: ZRAM_IDLE);
1261
1262	if (zram_test_flag(zram, index, flag: ZRAM_HUGE)) {
1263	zram_clear_flag(zram, index, flag: ZRAM_HUGE);
1264	atomic64_dec(v: &zram->stats.huge_pages);
1265	}
1266
1267	if (zram_test_flag(zram, index, flag: ZRAM_INCOMPRESSIBLE))
1268	zram_clear_flag(zram, index, flag: ZRAM_INCOMPRESSIBLE);
1269
1270	zram_set_priority(zram, index, prio: 0);
1271
1272	if (zram_test_flag(zram, index, flag: ZRAM_WB)) {
1273	zram_clear_flag(zram, index, flag: ZRAM_WB);
1274	free_block_bdev(zram, blk_idx: zram_get_element(zram, index));
1275	goto out;
1276	}
1277
1278	/*
1279	* No memory is allocated for same element filled pages.
1280	* Simply clear same page flag.
1281	*/
1282	if (zram_test_flag(zram, index, flag: ZRAM_SAME)) {
1283	zram_clear_flag(zram, index, flag: ZRAM_SAME);
1284	atomic64_dec(v: &zram->stats.same_pages);
1285	goto out;
1286	}
1287
1288	handle = zram_get_handle(zram, index);
1289	if (!handle)
1290	return;
1291
1292	zs_free(pool: zram->mem_pool, obj: handle);
1293
1294	atomic64_sub(i: zram_get_obj_size(zram, index),
1295	v: &zram->stats.compr_data_size);
1296	out:
1297	atomic64_dec(v: &zram->stats.pages_stored);
1298	zram_set_handle(zram, index, handle: 0);
1299	zram_set_obj_size(zram, index, size: 0);
1300	WARN_ON_ONCE(zram->table[index].flags &
1301	~(1UL << ZRAM_LOCK | 1UL << ZRAM_UNDER_WB));
1302	}
1303
1304	/*
1305	* Reads (decompresses if needed) a page from zspool (zsmalloc).
1306	* Corresponding ZRAM slot should be locked.
1307	*/
1308	static int zram_read_from_zspool(struct zram *zram, struct page *page,
1309	u32 index)
1310	{
1311	struct zcomp_strm *zstrm;
1312	unsigned long handle;
1313	unsigned int size;
1314	void *src, *dst;
1315	u32 prio;
1316	int ret;
1317
1318	handle = zram_get_handle(zram, index);
1319	if (!handle || zram_test_flag(zram, index, flag: ZRAM_SAME)) {
1320	unsigned long value;
1321	void *mem;
1322
1323	value = handle ? zram_get_element(zram, index) : 0;
1324	mem = kmap_local_page(page);
1325	zram_fill_page(ptr: mem, PAGE_SIZE, value);
1326	kunmap_local(mem);
1327	return 0;
1328	}
1329
1330	size = zram_get_obj_size(zram, index);
1331
1332	if (size != PAGE_SIZE) {
1333	prio = zram_get_priority(zram, index);
1334	zstrm = zcomp_stream_get(comp: zram->comps[prio]);
1335	}
1336
1337	src = zs_map_object(pool: zram->mem_pool, handle, mm: ZS_MM_RO);
1338	if (size == PAGE_SIZE) {
1339	dst = kmap_local_page(page);
1340	copy_page(to: dst, from: src);
1341	kunmap_local(dst);
1342	ret = 0;
1343	} else {
1344	dst = kmap_local_page(page);
1345	ret = zcomp_decompress(zstrm, src, src_len: size, dst);
1346	kunmap_local(dst);
1347	zcomp_stream_put(comp: zram->comps[prio]);
1348	}
1349	zs_unmap_object(pool: zram->mem_pool, handle);
1350	return ret;
1351	}
1352
1353	static int zram_read_page(struct zram *zram, struct page *page, u32 index,
1354	struct bio *parent)
1355	{
1356	int ret;
1357
1358	zram_slot_lock(zram, index);
1359	if (!zram_test_flag(zram, index, flag: ZRAM_WB)) {
1360	/* Slot should be locked through out the function call */
1361	ret = zram_read_from_zspool(zram, page, index);
1362	zram_slot_unlock(zram, index);
1363	} else {
1364	/*
1365	* The slot should be unlocked before reading from the backing
1366	* device.
1367	*/
1368	zram_slot_unlock(zram, index);
1369
1370	ret = read_from_bdev(zram, page, entry: zram_get_element(zram, index),
1371	parent);
1372	}
1373
1374	/* Should NEVER happen. Return bio error if it does. */
1375	if (WARN_ON(ret < 0))
1376	pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
1377
1378	return ret;
1379	}
1380
1381	/*
1382	* Use a temporary buffer to decompress the page, as the decompressor
1383	* always expects a full page for the output.
1384	*/
1385	static int zram_bvec_read_partial(struct zram *zram, struct bio_vec *bvec,
1386	u32 index, int offset)
1387	{
1388	struct page *page = alloc_page(GFP_NOIO);
1389	int ret;
1390
1391	if (!page)
1392	return -ENOMEM;
1393	ret = zram_read_page(zram, page, index, NULL);
1394	if (likely(!ret))
1395	memcpy_to_bvec(bvec, page_address(page) + offset);
1396	__free_page(page);
1397	return ret;
1398	}
1399
1400	static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
1401	u32 index, int offset, struct bio *bio)
1402	{
1403	if (is_partial_io(bvec))
1404	return zram_bvec_read_partial(zram, bvec, index, offset);
1405	return zram_read_page(zram, page: bvec->bv_page, index, parent: bio);
1406	}
1407
1408	static int zram_write_page(struct zram *zram, struct page *page, u32 index)
1409	{
1410	int ret = 0;
1411	unsigned long alloced_pages;
1412	unsigned long handle = -ENOMEM;
1413	unsigned int comp_len = 0;
1414	void *src, *dst, *mem;
1415	struct zcomp_strm *zstrm;
1416	unsigned long element = 0;
1417	enum zram_pageflags flags = 0;
1418
1419	mem = kmap_local_page(page);
1420	if (page_same_filled(ptr: mem, element: &element)) {
1421	kunmap_local(mem);
1422	/* Free memory associated with this sector now. */
1423	flags = ZRAM_SAME;
1424	atomic64_inc(v: &zram->stats.same_pages);
1425	goto out;
1426	}
1427	kunmap_local(mem);
1428
1429	compress_again:
1430	zstrm = zcomp_stream_get(comp: zram->comps[ZRAM_PRIMARY_COMP]);
1431	src = kmap_local_page(page);
1432	ret = zcomp_compress(zstrm, src, dst_len: &comp_len);
1433	kunmap_local(src);
1434
1435	if (unlikely(ret)) {
1436	zcomp_stream_put(comp: zram->comps[ZRAM_PRIMARY_COMP]);
1437	pr_err("Compression failed! err=%d\n", ret);
1438	zs_free(pool: zram->mem_pool, obj: handle);
1439	return ret;
1440	}
1441
1442	if (comp_len >= huge_class_size)
1443	comp_len = PAGE_SIZE;
1444	/*
1445	* handle allocation has 2 paths:
1446	* a) fast path is executed with preemption disabled (for
1447	* per-cpu streams) and has __GFP_DIRECT_RECLAIM bit clear,
1448	* since we can't sleep;
1449	* b) slow path enables preemption and attempts to allocate
1450	* the page with __GFP_DIRECT_RECLAIM bit set. we have to
1451	* put per-cpu compression stream and, thus, to re-do
1452	* the compression once handle is allocated.
1453	*
1454	* if we have a 'non-null' handle here then we are coming
1455	* from the slow path and handle has already been allocated.
1456	*/
1457	if (IS_ERR_VALUE(handle))
1458	handle = zs_malloc(pool: zram->mem_pool, size: comp_len,
1459	__GFP_KSWAPD_RECLAIM |
1460	__GFP_NOWARN |
1461	__GFP_HIGHMEM |
1462	__GFP_MOVABLE);
1463	if (IS_ERR_VALUE(handle)) {
1464	zcomp_stream_put(comp: zram->comps[ZRAM_PRIMARY_COMP]);
1465	atomic64_inc(v: &zram->stats.writestall);
1466	handle = zs_malloc(pool: zram->mem_pool, size: comp_len,
1467	GFP_NOIO | __GFP_HIGHMEM |
1468	__GFP_MOVABLE);
1469	if (IS_ERR_VALUE(handle))
1470	return PTR_ERR(ptr: (void *)handle);
1471
1472	if (comp_len != PAGE_SIZE)
1473	goto compress_again;
1474	/*
1475	* If the page is not compressible, you need to acquire the
1476	* lock and execute the code below. The zcomp_stream_get()
1477	* call is needed to disable the cpu hotplug and grab the
1478	* zstrm buffer back. It is necessary that the dereferencing
1479	* of the zstrm variable below occurs correctly.
1480	*/
1481	zstrm = zcomp_stream_get(comp: zram->comps[ZRAM_PRIMARY_COMP]);
1482	}
1483
1484	alloced_pages = zs_get_total_pages(pool: zram->mem_pool);
1485	update_used_max(zram, pages: alloced_pages);
1486
1487	if (zram->limit_pages && alloced_pages > zram->limit_pages) {
1488	zcomp_stream_put(comp: zram->comps[ZRAM_PRIMARY_COMP]);
1489	zs_free(pool: zram->mem_pool, obj: handle);
1490	return -ENOMEM;
1491	}
1492
1493	dst = zs_map_object(pool: zram->mem_pool, handle, mm: ZS_MM_WO);
1494
1495	src = zstrm->buffer;
1496	if (comp_len == PAGE_SIZE)
1497	src = kmap_local_page(page);
1498	memcpy(dst, src, comp_len);
1499	if (comp_len == PAGE_SIZE)
1500	kunmap_local(src);
1501
1502	zcomp_stream_put(comp: zram->comps[ZRAM_PRIMARY_COMP]);
1503	zs_unmap_object(pool: zram->mem_pool, handle);
1504	atomic64_add(i: comp_len, v: &zram->stats.compr_data_size);
1505	out:
1506	/*
1507	* Free memory associated with this sector
1508	* before overwriting unused sectors.
1509	*/
1510	zram_slot_lock(zram, index);
1511	zram_free_page(zram, index);
1512
1513	if (comp_len == PAGE_SIZE) {
1514	zram_set_flag(zram, index, flag: ZRAM_HUGE);
1515	atomic64_inc(v: &zram->stats.huge_pages);
1516	atomic64_inc(v: &zram->stats.huge_pages_since);
1517	}
1518
1519	if (flags) {
1520	zram_set_flag(zram, index, flag: flags);
1521	zram_set_element(zram, index, element);
1522	} else {
1523	zram_set_handle(zram, index, handle);
1524	zram_set_obj_size(zram, index, size: comp_len);
1525	}
1526	zram_slot_unlock(zram, index);
1527
1528	/* Update stats */
1529	atomic64_inc(v: &zram->stats.pages_stored);
1530	return ret;
1531	}
1532
1533	/*
1534	* This is a partial IO. Read the full page before writing the changes.
1535	*/
1536	static int zram_bvec_write_partial(struct zram *zram, struct bio_vec *bvec,
1537	u32 index, int offset, struct bio *bio)
1538	{
1539	struct page *page = alloc_page(GFP_NOIO);
1540	int ret;
1541
1542	if (!page)
1543	return -ENOMEM;
1544
1545	ret = zram_read_page(zram, page, index, parent: bio);
1546	if (!ret) {
1547	memcpy_from_bvec(page_address(page) + offset, bvec);
1548	ret = zram_write_page(zram, page, index);
1549	}
1550	__free_page(page);
1551	return ret;
1552	}
1553
1554	static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
1555	u32 index, int offset, struct bio *bio)
1556	{
1557	if (is_partial_io(bvec))
1558	return zram_bvec_write_partial(zram, bvec, index, offset, bio);
1559	return zram_write_page(zram, page: bvec->bv_page, index);
1560	}
1561
1562	#ifdef CONFIG_ZRAM_MULTI_COMP
1563	/*
1564	* This function will decompress (unless it's ZRAM_HUGE) the page and then
1565	* attempt to compress it using provided compression algorithm priority
1566	* (which is potentially more effective).
1567	*
1568	* Corresponding ZRAM slot should be locked.
1569	*/
1570	static int zram_recompress(struct zram *zram, u32 index, struct page *page,
1571	u32 threshold, u32 prio, u32 prio_max)
1572	{
1573	struct zcomp_strm *zstrm = NULL;
1574	unsigned long handle_old;
1575	unsigned long handle_new;
1576	unsigned int comp_len_old;
1577	unsigned int comp_len_new;
1578	unsigned int class_index_old;
1579	unsigned int class_index_new;
1580	u32 num_recomps = 0;
1581	void *src, *dst;
1582	int ret;
1583
1584	handle_old = zram_get_handle(zram, index);
1585	if (!handle_old)
1586	return -EINVAL;
1587
1588	comp_len_old = zram_get_obj_size(zram, index);
1589	/*
1590	* Do not recompress objects that are already "small enough".
1591	*/
1592	if (comp_len_old < threshold)
1593	return 0;
1594
1595	ret = zram_read_from_zspool(zram, page, index);
1596	if (ret)
1597	return ret;
1598
1599	class_index_old = zs_lookup_class_index(pool: zram->mem_pool, size: comp_len_old);
1600	/*
1601	* Iterate the secondary comp algorithms list (in order of priority)
1602	* and try to recompress the page.
1603	*/
1604	for (; prio < prio_max; prio++) {
1605	if (!zram->comps[prio])
1606	continue;
1607
1608	/*
1609	* Skip if the object is already re-compressed with a higher
1610	* priority algorithm (or same algorithm).
1611	*/
1612	if (prio <= zram_get_priority(zram, index))
1613	continue;
1614
1615	num_recomps++;
1616	zstrm = zcomp_stream_get(comp: zram->comps[prio]);
1617	src = kmap_local_page(page);
1618	ret = zcomp_compress(zstrm, src, dst_len: &comp_len_new);
1619	kunmap_local(src);
1620
1621	if (ret) {
1622	zcomp_stream_put(comp: zram->comps[prio]);
1623	return ret;
1624	}
1625
1626	class_index_new = zs_lookup_class_index(pool: zram->mem_pool,
1627	size: comp_len_new);
1628
1629	/* Continue until we make progress */
1630	if (class_index_new >= class_index_old ||
1631	(threshold && comp_len_new >= threshold)) {
1632	zcomp_stream_put(comp: zram->comps[prio]);
1633	continue;
1634	}
1635
1636	/* Recompression was successful so break out */
1637	break;
1638	}
1639
1640	/*
1641	* We did not try to recompress, e.g. when we have only one
1642	* secondary algorithm and the page is already recompressed
1643	* using that algorithm
1644	*/
1645	if (!zstrm)
1646	return 0;
1647
1648	if (class_index_new >= class_index_old) {
1649	/*
1650	* Secondary algorithms failed to re-compress the page
1651	* in a way that would save memory, mark the object as
1652	* incompressible so that we will not try to compress
1653	* it again.
1654	*
1655	* We need to make sure that all secondary algorithms have
1656	* failed, so we test if the number of recompressions matches
1657	* the number of active secondary algorithms.
1658	*/
1659	if (num_recomps == zram->num_active_comps - 1)
1660	zram_set_flag(zram, index, flag: ZRAM_INCOMPRESSIBLE);
1661	return 0;
1662	}
1663
1664	/* Successful recompression but above threshold */
1665	if (threshold && comp_len_new >= threshold)
1666	return 0;
1667
1668	/*
1669	* No direct reclaim (slow path) for handle allocation and no
1670	* re-compression attempt (unlike in zram_write_bvec()) since
1671	* we already have stored that object in zsmalloc. If we cannot
1672	* alloc memory for recompressed object then we bail out and
1673	* simply keep the old (existing) object in zsmalloc.
1674	*/
1675	handle_new = zs_malloc(pool: zram->mem_pool, size: comp_len_new,
1676	__GFP_KSWAPD_RECLAIM |
1677	__GFP_NOWARN |
1678	__GFP_HIGHMEM |
1679	__GFP_MOVABLE);
1680	if (IS_ERR_VALUE(handle_new)) {
1681	zcomp_stream_put(comp: zram->comps[prio]);
1682	return PTR_ERR(ptr: (void *)handle_new);
1683	}
1684
1685	dst = zs_map_object(pool: zram->mem_pool, handle: handle_new, mm: ZS_MM_WO);
1686	memcpy(dst, zstrm->buffer, comp_len_new);
1687	zcomp_stream_put(comp: zram->comps[prio]);
1688
1689	zs_unmap_object(pool: zram->mem_pool, handle: handle_new);
1690
1691	zram_free_page(zram, index);
1692	zram_set_handle(zram, index, handle: handle_new);
1693	zram_set_obj_size(zram, index, size: comp_len_new);
1694	zram_set_priority(zram, index, prio);
1695
1696	atomic64_add(i: comp_len_new, v: &zram->stats.compr_data_size);
1697	atomic64_inc(v: &zram->stats.pages_stored);
1698
1699	return 0;
1700	}
1701
1702	#define RECOMPRESS_IDLE (1 << 0)
1703	#define RECOMPRESS_HUGE (1 << 1)
1704
1705	static ssize_t recompress_store(struct device *dev,
1706	struct device_attribute *attr,
1707	const char *buf, size_t len)
1708	{
1709	u32 prio = ZRAM_SECONDARY_COMP, prio_max = ZRAM_MAX_COMPS;
1710	struct zram *zram = dev_to_zram(dev);
1711	unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
1712	char *args, *param, *val, *algo = NULL;
1713	u32 mode = 0, threshold = 0;
1714	unsigned long index;
1715	struct page *page;
1716	ssize_t ret;
1717
1718	args = skip_spaces(buf);
1719	while (*args) {
1720	args = next_arg(args, param: &param, val: &val);
1721
1722	if (!val || !*val)
1723	return -EINVAL;
1724
1725	if (!strcmp(param, "type")) {
1726	if (!strcmp(val, "idle"))
1727	mode = RECOMPRESS_IDLE;
1728	if (!strcmp(val, "huge"))
1729	mode = RECOMPRESS_HUGE;
1730	if (!strcmp(val, "huge_idle"))
1731	mode = RECOMPRESS_IDLE | RECOMPRESS_HUGE;
1732	continue;
1733	}
1734
1735	if (!strcmp(param, "threshold")) {
1736	/*
1737	* We will re-compress only idle objects equal or
1738	* greater in size than watermark.
1739	*/
1740	ret = kstrtouint(s: val, base: 10, res: &threshold);
1741	if (ret)
1742	return ret;
1743	continue;
1744	}
1745
1746	if (!strcmp(param, "algo")) {
1747	algo = val;
1748	continue;
1749	}
1750	}
1751
1752	if (threshold >= huge_class_size)
1753	return -EINVAL;
1754
1755	down_read(sem: &zram->init_lock);
1756	if (!init_done(zram)) {
1757	ret = -EINVAL;
1758	goto release_init_lock;
1759	}
1760
1761	if (algo) {
1762	bool found = false;
1763
1764	for (; prio < ZRAM_MAX_COMPS; prio++) {
1765	if (!zram->comp_algs[prio])
1766	continue;
1767
1768	if (!strcmp(zram->comp_algs[prio], algo)) {
1769	prio_max = min(prio + 1, ZRAM_MAX_COMPS);
1770	found = true;
1771	break;
1772	}
1773	}
1774
1775	if (!found) {
1776	ret = -EINVAL;
1777	goto release_init_lock;
1778	}
1779	}
1780
1781	page = alloc_page(GFP_KERNEL);
1782	if (!page) {
1783	ret = -ENOMEM;
1784	goto release_init_lock;
1785	}
1786
1787	ret = len;
1788	for (index = 0; index < nr_pages; index++) {
1789	int err = 0;
1790
1791	zram_slot_lock(zram, index);
1792
1793	if (!zram_allocated(zram, index))
1794	goto next;
1795
1796	if (mode & RECOMPRESS_IDLE &&
1797	!zram_test_flag(zram, index, flag: ZRAM_IDLE))
1798	goto next;
1799
1800	if (mode & RECOMPRESS_HUGE &&
1801	!zram_test_flag(zram, index, flag: ZRAM_HUGE))
1802	goto next;
1803
1804	if (zram_test_flag(zram, index, flag: ZRAM_WB) ||
1805	zram_test_flag(zram, index, flag: ZRAM_UNDER_WB) ||
1806	zram_test_flag(zram, index, flag: ZRAM_SAME) ||
1807	zram_test_flag(zram, index, flag: ZRAM_INCOMPRESSIBLE))
1808	goto next;
1809
1810	err = zram_recompress(zram, index, page, threshold,
1811	prio, prio_max);
1812	next:
1813	zram_slot_unlock(zram, index);
1814	if (err) {
1815	ret = err;
1816	break;
1817	}
1818
1819	cond_resched();
1820	}
1821
1822	__free_page(page);
1823
1824	release_init_lock:
1825	up_read(sem: &zram->init_lock);
1826	return ret;
1827	}
1828	#endif
1829
1830	static void zram_bio_discard(struct zram *zram, struct bio *bio)
1831	{
1832	size_t n = bio->bi_iter.bi_size;
1833	u32 index = bio->bi_iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
1834	u32 offset = (bio->bi_iter.bi_sector & (SECTORS_PER_PAGE - 1)) <<
1835	SECTOR_SHIFT;
1836
1837	/*
1838	* zram manages data in physical block size units. Because logical block
1839	* size isn't identical with physical block size on some arch, we
1840	* could get a discard request pointing to a specific offset within a
1841	* certain physical block. Although we can handle this request by
1842	* reading that physiclal block and decompressing and partially zeroing
1843	* and re-compressing and then re-storing it, this isn't reasonable
1844	* because our intent with a discard request is to save memory. So
1845	* skipping this logical block is appropriate here.
1846	*/
1847	if (offset) {
1848	if (n <= (PAGE_SIZE - offset))
1849	return;
1850
1851	n -= (PAGE_SIZE - offset);
1852	index++;
1853	}
1854
1855	while (n >= PAGE_SIZE) {
1856	zram_slot_lock(zram, index);
1857	zram_free_page(zram, index);
1858	zram_slot_unlock(zram, index);
1859	atomic64_inc(v: &zram->stats.notify_free);
1860	index++;
1861	n -= PAGE_SIZE;
1862	}
1863
1864	bio_endio(bio);
1865	}
1866
1867	static void zram_bio_read(struct zram *zram, struct bio *bio)
1868	{
1869	unsigned long start_time = bio_start_io_acct(bio);
1870	struct bvec_iter iter = bio->bi_iter;
1871
1872	do {
1873	u32 index = iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
1874	u32 offset = (iter.bi_sector & (SECTORS_PER_PAGE - 1)) <<
1875	SECTOR_SHIFT;
1876	struct bio_vec bv = bio_iter_iovec(bio, iter);
1877
1878	bv.bv_len = min_t(u32, bv.bv_len, PAGE_SIZE - offset);
1879
1880	if (zram_bvec_read(zram, bvec: &bv, index, offset, bio) < 0) {
1881	atomic64_inc(v: &zram->stats.failed_reads);
1882	bio->bi_status = BLK_STS_IOERR;
1883	break;
1884	}
1885	flush_dcache_page(page: bv.bv_page);
1886
1887	zram_slot_lock(zram, index);
1888	zram_accessed(zram, index);
1889	zram_slot_unlock(zram, index);
1890
1891	bio_advance_iter_single(bio, iter: &iter, bytes: bv.bv_len);
1892	} while (iter.bi_size);
1893
1894	bio_end_io_acct(bio, start_time);
1895	bio_endio(bio);
1896	}
1897
1898	static void zram_bio_write(struct zram *zram, struct bio *bio)
1899	{
1900	unsigned long start_time = bio_start_io_acct(bio);
1901	struct bvec_iter iter = bio->bi_iter;
1902
1903	do {
1904	u32 index = iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
1905	u32 offset = (iter.bi_sector & (SECTORS_PER_PAGE - 1)) <<
1906	SECTOR_SHIFT;
1907	struct bio_vec bv = bio_iter_iovec(bio, iter);
1908
1909	bv.bv_len = min_t(u32, bv.bv_len, PAGE_SIZE - offset);
1910
1911	if (zram_bvec_write(zram, bvec: &bv, index, offset, bio) < 0) {
1912	atomic64_inc(v: &zram->stats.failed_writes);
1913	bio->bi_status = BLK_STS_IOERR;
1914	break;
1915	}
1916
1917	zram_slot_lock(zram, index);
1918	zram_accessed(zram, index);
1919	zram_slot_unlock(zram, index);
1920
1921	bio_advance_iter_single(bio, iter: &iter, bytes: bv.bv_len);
1922	} while (iter.bi_size);
1923
1924	bio_end_io_acct(bio, start_time);
1925	bio_endio(bio);
1926	}
1927
1928	/*
1929	* Handler function for all zram I/O requests.
1930	*/
1931	static void zram_submit_bio(struct bio *bio)
1932	{
1933	struct zram *zram = bio->bi_bdev->bd_disk->private_data;
1934
1935	switch (bio_op(bio)) {
1936	case REQ_OP_READ:
1937	zram_bio_read(zram, bio);
1938	break;
1939	case REQ_OP_WRITE:
1940	zram_bio_write(zram, bio);
1941	break;
1942	case REQ_OP_DISCARD:
1943	case REQ_OP_WRITE_ZEROES:
1944	zram_bio_discard(zram, bio);
1945	break;
1946	default:
1947	WARN_ON_ONCE(1);
1948	bio_endio(bio);
1949	}
1950	}
1951
1952	static void zram_slot_free_notify(struct block_device *bdev,
1953	unsigned long index)
1954	{
1955	struct zram *zram;
1956
1957	zram = bdev->bd_disk->private_data;
1958
1959	atomic64_inc(v: &zram->stats.notify_free);
1960	if (!zram_slot_trylock(zram, index)) {
1961	atomic64_inc(v: &zram->stats.miss_free);
1962	return;
1963	}
1964
1965	zram_free_page(zram, index);
1966	zram_slot_unlock(zram, index);
1967	}
1968
1969	static void zram_destroy_comps(struct zram *zram)
1970	{
1971	u32 prio;
1972
1973	for (prio = 0; prio < ZRAM_MAX_COMPS; prio++) {
1974	struct zcomp *comp = zram->comps[prio];
1975
1976	zram->comps[prio] = NULL;
1977	if (!comp)
1978	continue;
1979	zcomp_destroy(comp);
1980	zram->num_active_comps--;
1981	}
1982	}
1983
1984	static void zram_reset_device(struct zram *zram)
1985	{
1986	down_write(sem: &zram->init_lock);
1987
1988	zram->limit_pages = 0;
1989
1990	if (!init_done(zram)) {
1991	up_write(sem: &zram->init_lock);
1992	return;
1993	}
1994
1995	set_capacity_and_notify(disk: zram->disk, size: 0);
1996	part_stat_set_all(part: zram->disk->part0, value: 0);
1997
1998	/* I/O operation under all of CPU are done so let's free */
1999	zram_meta_free(zram, disksize: zram->disksize);
2000	zram->disksize = 0;
2001	zram_destroy_comps(zram);
2002	memset(&zram->stats, 0, sizeof(zram->stats));
2003	reset_bdev(zram);
2004
2005	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, alg: default_compressor);
2006	up_write(sem: &zram->init_lock);
2007	}
2008
2009	static ssize_t disksize_store(struct device *dev,
2010	struct device_attribute *attr, const char *buf, size_t len)
2011	{
2012	u64 disksize;
2013	struct zcomp *comp;
2014	struct zram *zram = dev_to_zram(dev);
2015	int err;
2016	u32 prio;
2017
2018	disksize = memparse(ptr: buf, NULL);
2019	if (!disksize)
2020	return -EINVAL;
2021
2022	down_write(sem: &zram->init_lock);
2023	if (init_done(zram)) {
2024	pr_info("Cannot change disksize for initialized device\n");
2025	err = -EBUSY;
2026	goto out_unlock;
2027	}
2028
2029	disksize = PAGE_ALIGN(disksize);
2030	if (!zram_meta_alloc(zram, disksize)) {
2031	err = -ENOMEM;
2032	goto out_unlock;
2033	}
2034
2035	for (prio = 0; prio < ZRAM_MAX_COMPS; prio++) {
2036	if (!zram->comp_algs[prio])
2037	continue;
2038
2039	comp = zcomp_create(alg: zram->comp_algs[prio]);
2040	if (IS_ERR(ptr: comp)) {
2041	pr_err("Cannot initialise %s compressing backend\n",
2042	zram->comp_algs[prio]);
2043	err = PTR_ERR(ptr: comp);
2044	goto out_free_comps;
2045	}
2046
2047	zram->comps[prio] = comp;
2048	zram->num_active_comps++;
2049	}
2050	zram->disksize = disksize;
2051	set_capacity_and_notify(disk: zram->disk, size: zram->disksize >> SECTOR_SHIFT);
2052	up_write(sem: &zram->init_lock);
2053
2054	return len;
2055
2056	out_free_comps:
2057	zram_destroy_comps(zram);
2058	zram_meta_free(zram, disksize);
2059	out_unlock:
2060	up_write(sem: &zram->init_lock);
2061	return err;
2062	}
2063
2064	static ssize_t reset_store(struct device *dev,
2065	struct device_attribute *attr, const char *buf, size_t len)
2066	{
2067	int ret;
2068	unsigned short do_reset;
2069	struct zram *zram;
2070	struct gendisk *disk;
2071
2072	ret = kstrtou16(s: buf, base: 10, res: &do_reset);
2073	if (ret)
2074	return ret;
2075
2076	if (!do_reset)
2077	return -EINVAL;
2078
2079	zram = dev_to_zram(dev);
2080	disk = zram->disk;
2081
2082	mutex_lock(&disk->open_mutex);
2083	/* Do not reset an active device or claimed device */
2084	if (disk_openers(disk) || zram->claim) {
2085	mutex_unlock(lock: &disk->open_mutex);
2086	return -EBUSY;
2087	}
2088
2089	/* From now on, anyone can't open /dev/zram[0-9] */
2090	zram->claim = true;
2091	mutex_unlock(lock: &disk->open_mutex);
2092
2093	/* Make sure all the pending I/O are finished */
2094	sync_blockdev(bdev: disk->part0);
2095	zram_reset_device(zram);
2096
2097	mutex_lock(&disk->open_mutex);
2098	zram->claim = false;
2099	mutex_unlock(lock: &disk->open_mutex);
2100
2101	return len;
2102	}
2103
2104	static int zram_open(struct gendisk *disk, blk_mode_t mode)
2105	{
2106	struct zram *zram = disk->private_data;
2107
2108	WARN_ON(!mutex_is_locked(&disk->open_mutex));
2109
2110	/* zram was claimed to reset so open request fails */
2111	if (zram->claim)
2112	return -EBUSY;
2113	return 0;
2114	}
2115
2116	static const struct block_device_operations zram_devops = {
2117	.open = zram_open,
2118	.submit_bio = zram_submit_bio,
2119	.swap_slot_free_notify = zram_slot_free_notify,
2120	.owner = THIS_MODULE
2121	};
2122
2123	static DEVICE_ATTR_WO(compact);
2124	static DEVICE_ATTR_RW(disksize);
2125	static DEVICE_ATTR_RO(initstate);
2126	static DEVICE_ATTR_WO(reset);
2127	static DEVICE_ATTR_WO(mem_limit);
2128	static DEVICE_ATTR_WO(mem_used_max);
2129	static DEVICE_ATTR_WO(idle);
2130	static DEVICE_ATTR_RW(max_comp_streams);
2131	static DEVICE_ATTR_RW(comp_algorithm);
2132	#ifdef CONFIG_ZRAM_WRITEBACK
2133	static DEVICE_ATTR_RW(backing_dev);
2134	static DEVICE_ATTR_WO(writeback);
2135	static DEVICE_ATTR_RW(writeback_limit);
2136	static DEVICE_ATTR_RW(writeback_limit_enable);
2137	#endif
2138	#ifdef CONFIG_ZRAM_MULTI_COMP
2139	static DEVICE_ATTR_RW(recomp_algorithm);
2140	static DEVICE_ATTR_WO(recompress);
2141	#endif
2142
2143	static struct attribute *zram_disk_attrs[] = {
2144	&dev_attr_disksize.attr,
2145	&dev_attr_initstate.attr,
2146	&dev_attr_reset.attr,
2147	&dev_attr_compact.attr,
2148	&dev_attr_mem_limit.attr,
2149	&dev_attr_mem_used_max.attr,
2150	&dev_attr_idle.attr,
2151	&dev_attr_max_comp_streams.attr,
2152	&dev_attr_comp_algorithm.attr,
2153	#ifdef CONFIG_ZRAM_WRITEBACK
2154	&dev_attr_backing_dev.attr,
2155	&dev_attr_writeback.attr,
2156	&dev_attr_writeback_limit.attr,
2157	&dev_attr_writeback_limit_enable.attr,
2158	#endif
2159	&dev_attr_io_stat.attr,
2160	&dev_attr_mm_stat.attr,
2161	#ifdef CONFIG_ZRAM_WRITEBACK
2162	&dev_attr_bd_stat.attr,
2163	#endif
2164	&dev_attr_debug_stat.attr,
2165	#ifdef CONFIG_ZRAM_MULTI_COMP
2166	&dev_attr_recomp_algorithm.attr,
2167	&dev_attr_recompress.attr,
2168	#endif
2169	NULL,
2170	};
2171
2172	ATTRIBUTE_GROUPS(zram_disk);
2173
2174	/*
2175	* Allocate and initialize new zram device. the function returns
2176	* '>= 0' device_id upon success, and negative value otherwise.
2177	*/
2178	static int zram_add(void)
2179	{
2180	struct queue_limits lim = {
2181	.logical_block_size = ZRAM_LOGICAL_BLOCK_SIZE,
2182	/*
2183	* To ensure that we always get PAGE_SIZE aligned and
2184	* n*PAGE_SIZED sized I/O requests.
2185	*/
2186	.physical_block_size = PAGE_SIZE,
2187	.io_min = PAGE_SIZE,
2188	.io_opt = PAGE_SIZE,
2189	.max_hw_discard_sectors = UINT_MAX,
2190	/*
2191	* zram_bio_discard() will clear all logical blocks if logical
2192	* block size is identical with physical block size(PAGE_SIZE).
2193	* But if it is different, we will skip discarding some parts of
2194	* logical blocks in the part of the request range which isn't
2195	* aligned to physical block size. So we can't ensure that all
2196	* discarded logical blocks are zeroed.
2197	*/
2198	#if ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE
2199	.max_write_zeroes_sectors = UINT_MAX,
2200	#endif
2201	};
2202	struct zram *zram;
2203	int ret, device_id;
2204
2205	zram = kzalloc(size: sizeof(struct zram), GFP_KERNEL);
2206	if (!zram)
2207	return -ENOMEM;
2208
2209	ret = idr_alloc(&zram_index_idr, ptr: zram, start: 0, end: 0, GFP_KERNEL);
2210	if (ret < 0)
2211	goto out_free_dev;
2212	device_id = ret;
2213
2214	init_rwsem(&zram->init_lock);
2215	#ifdef CONFIG_ZRAM_WRITEBACK
2216	spin_lock_init(&zram->wb_limit_lock);
2217	#endif
2218
2219	/* gendisk structure */
2220	zram->disk = blk_alloc_disk(&lim, NUMA_NO_NODE);
2221	if (IS_ERR(ptr: zram->disk)) {
2222	pr_err("Error allocating disk structure for device %d\n",
2223	device_id);
2224	ret = PTR_ERR(ptr: zram->disk);
2225	goto out_free_idr;
2226	}
2227
2228	zram->disk->major = zram_major;
2229	zram->disk->first_minor = device_id;
2230	zram->disk->minors = 1;
2231	zram->disk->flags |= GENHD_FL_NO_PART;
2232	zram->disk->fops = &zram_devops;
2233	zram->disk->private_data = zram;
2234	snprintf(buf: zram->disk->disk_name, size: 16, fmt: "zram%d", device_id);
2235
2236	/* Actual capacity set using sysfs (/sys/block/zram<id>/disksize */
2237	set_capacity(disk: zram->disk, size: 0);
2238	/* zram devices sort of resembles non-rotational disks */
2239	blk_queue_flag_set(QUEUE_FLAG_NONROT, q: zram->disk->queue);
2240	blk_queue_flag_set(QUEUE_FLAG_SYNCHRONOUS, q: zram->disk->queue);
2241	blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, q: zram->disk->queue);
2242	ret = device_add_disk(NULL, disk: zram->disk, groups: zram_disk_groups);
2243	if (ret)
2244	goto out_cleanup_disk;
2245
2246	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, alg: default_compressor);
2247
2248	zram_debugfs_register(zram);
2249	pr_info("Added device: %s\n", zram->disk->disk_name);
2250	return device_id;
2251
2252	out_cleanup_disk:
2253	put_disk(disk: zram->disk);
2254	out_free_idr:
2255	idr_remove(&zram_index_idr, id: device_id);
2256	out_free_dev:
2257	kfree(objp: zram);
2258	return ret;
2259	}
2260
2261	static int zram_remove(struct zram *zram)
2262	{
2263	bool claimed;
2264
2265	mutex_lock(&zram->disk->open_mutex);
2266	if (disk_openers(disk: zram->disk)) {
2267	mutex_unlock(lock: &zram->disk->open_mutex);
2268	return -EBUSY;
2269	}
2270
2271	claimed = zram->claim;
2272	if (!claimed)
2273	zram->claim = true;
2274	mutex_unlock(lock: &zram->disk->open_mutex);
2275
2276	zram_debugfs_unregister(zram);
2277
2278	if (claimed) {
2279	/*
2280	* If we were claimed by reset_store(), del_gendisk() will
2281	* wait until reset_store() is done, so nothing need to do.
2282	*/
2283	;
2284	} else {
2285	/* Make sure all the pending I/O are finished */
2286	sync_blockdev(bdev: zram->disk->part0);
2287	zram_reset_device(zram);
2288	}
2289
2290	pr_info("Removed device: %s\n", zram->disk->disk_name);
2291
2292	del_gendisk(gp: zram->disk);
2293
2294	/* del_gendisk drains pending reset_store */
2295	WARN_ON_ONCE(claimed && zram->claim);
2296
2297	/*
2298	* disksize_store() may be called in between zram_reset_device()
2299	* and del_gendisk(), so run the last reset to avoid leaking
2300	* anything allocated with disksize_store()
2301	*/
2302	zram_reset_device(zram);
2303
2304	put_disk(disk: zram->disk);
2305	kfree(objp: zram);
2306	return 0;
2307	}
2308
2309	/* zram-control sysfs attributes */
2310
2311	/*
2312	* NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
2313	* sense that reading from this file does alter the state of your system -- it
2314	* creates a new un-initialized zram device and returns back this device's
2315	* device_id (or an error code if it fails to create a new device).
2316	*/
2317	static ssize_t hot_add_show(const struct class *class,
2318	const struct class_attribute *attr,
2319	char *buf)
2320	{
2321	int ret;
2322
2323	mutex_lock(&zram_index_mutex);
2324	ret = zram_add();
2325	mutex_unlock(lock: &zram_index_mutex);
2326
2327	if (ret < 0)
2328	return ret;
2329	return scnprintf(buf, PAGE_SIZE, fmt: "%d\n", ret);
2330	}
2331	/* This attribute must be set to 0400, so CLASS_ATTR_RO() can not be used */
2332	static struct class_attribute class_attr_hot_add =
2333	__ATTR(hot_add, 0400, hot_add_show, NULL);
2334
2335	static ssize_t hot_remove_store(const struct class *class,
2336	const struct class_attribute *attr,
2337	const char *buf,
2338	size_t count)
2339	{
2340	struct zram *zram;
2341	int ret, dev_id;
2342
2343	/* dev_id is gendisk->first_minor, which is `int' */
2344	ret = kstrtoint(s: buf, base: 10, res: &dev_id);
2345	if (ret)
2346	return ret;
2347	if (dev_id < 0)
2348	return -EINVAL;
2349
2350	mutex_lock(&zram_index_mutex);
2351
2352	zram = idr_find(&zram_index_idr, id: dev_id);
2353	if (zram) {
2354	ret = zram_remove(zram);
2355	if (!ret)
2356	idr_remove(&zram_index_idr, id: dev_id);
2357	} else {
2358	ret = -ENODEV;
2359	}
2360
2361	mutex_unlock(lock: &zram_index_mutex);
2362	return ret ? ret : count;
2363	}
2364	static CLASS_ATTR_WO(hot_remove);
2365
2366	static struct attribute *zram_control_class_attrs[] = {
2367	&class_attr_hot_add.attr,
2368	&class_attr_hot_remove.attr,
2369	NULL,
2370	};
2371	ATTRIBUTE_GROUPS(zram_control_class);
2372
2373	static struct class zram_control_class = {
2374	.name = "zram-control",
2375	.class_groups = zram_control_class_groups,
2376	};
2377
2378	static int zram_remove_cb(int id, void *ptr, void *data)
2379	{
2380	WARN_ON_ONCE(zram_remove(ptr));
2381	return 0;
2382	}
2383
2384	static void destroy_devices(void)
2385	{
2386	class_unregister(class: &zram_control_class);
2387	idr_for_each(&zram_index_idr, fn: &zram_remove_cb, NULL);
2388	zram_debugfs_destroy();
2389	idr_destroy(&zram_index_idr);
2390	unregister_blkdev(major: zram_major, name: "zram");
2391	cpuhp_remove_multi_state(state: CPUHP_ZCOMP_PREPARE);
2392	}
2393
2394	static int __init zram_init(void)
2395	{
2396	int ret;
2397
2398	BUILD_BUG_ON(__NR_ZRAM_PAGEFLAGS > BITS_PER_LONG);
2399
2400	ret = cpuhp_setup_state_multi(state: CPUHP_ZCOMP_PREPARE, name: "block/zram:prepare",
2401	startup: zcomp_cpu_up_prepare, teardown: zcomp_cpu_dead);
2402	if (ret < 0)
2403	return ret;
2404
2405	ret = class_register(class: &zram_control_class);
2406	if (ret) {
2407	pr_err("Unable to register zram-control class\n");
2408	cpuhp_remove_multi_state(state: CPUHP_ZCOMP_PREPARE);
2409	return ret;
2410	}
2411
2412	zram_debugfs_create();
2413	zram_major = register_blkdev(0, "zram");
2414	if (zram_major <= 0) {
2415	pr_err("Unable to get major number\n");
2416	class_unregister(class: &zram_control_class);
2417	cpuhp_remove_multi_state(state: CPUHP_ZCOMP_PREPARE);
2418	return -EBUSY;
2419	}
2420
2421	while (num_devices != 0) {
2422	mutex_lock(&zram_index_mutex);
2423	ret = zram_add();
2424	mutex_unlock(lock: &zram_index_mutex);
2425	if (ret < 0)
2426	goto out_error;
2427	num_devices--;
2428	}
2429
2430	return 0;
2431
2432	out_error:
2433	destroy_devices();
2434	return ret;
2435	}
2436
2437	static void __exit zram_exit(void)
2438	{
2439	destroy_devices();
2440	}
2441
2442	module_init(zram_init);
2443	module_exit(zram_exit);
2444
2445	module_param(num_devices, uint, 0);
2446	MODULE_PARM_DESC(num_devices, "Number of pre-created zram devices");
2447
2448	MODULE_LICENSE("Dual BSD/GPL");
2449	MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
2450	MODULE_DESCRIPTION("Compressed RAM Block Device");
2451