1// SPDX-License-Identifier: GPL-2.0
2/*
3 * random utiility code, for bcache but in theory not specific to bcache
4 *
5 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
6 * Copyright 2012 Google, Inc.
7 */
8
9#include <linux/bio.h>
10#include <linux/blkdev.h>
11#include <linux/ctype.h>
12#include <linux/debugfs.h>
13#include <linux/module.h>
14#include <linux/seq_file.h>
15#include <linux/types.h>
16#include <linux/sched/clock.h>
17
18#include "util.h"
19
20#define simple_strtoint(c, end, base)	simple_strtol(c, end, base)
21#define simple_strtouint(c, end, base)	simple_strtoul(c, end, base)
22
23#define STRTO_H(name, type)					\
24int bch_ ## name ## _h(const char *cp, type *res)		\
25{								\
26	int u = 0;						\
27	char *e;						\
28	type i = simple_ ## name(cp, &e, 10);			\
29								\
30	switch (tolower(*e)) {					\
31	default:						\
32		return -EINVAL;					\
33	case 'y':						\
34	case 'z':						\
35		u++;						\
36		fallthrough;					\
37	case 'e':						\
38		u++;						\
39		fallthrough;					\
40	case 'p':						\
41		u++;						\
42		fallthrough;					\
43	case 't':						\
44		u++;						\
45		fallthrough;					\
46	case 'g':						\
47		u++;						\
48		fallthrough;					\
49	case 'm':						\
50		u++;						\
51		fallthrough;					\
52	case 'k':						\
53		u++;						\
54		if (e++ == cp)					\
55			return -EINVAL;				\
56		fallthrough;					\
57	case '\n':						\
58	case '\0':						\
59		if (*e == '\n')					\
60			e++;					\
61	}							\
62								\
63	if (*e)							\
64		return -EINVAL;					\
65								\
66	while (u--) {						\
67		if ((type) ~0 > 0 &&				\
68		    (type) ~0 / 1024 <= i)			\
69			return -EINVAL;				\
70		if ((i > 0 && ANYSINT_MAX(type) / 1024 < i) ||	\
71		    (i < 0 && -ANYSINT_MAX(type) / 1024 > i))	\
72			return -EINVAL;				\
73		i *= 1024;					\
74	}							\
75								\
76	*res = i;						\
77	return 0;						\
78}								\
79
80STRTO_H(strtoint, int)
81STRTO_H(strtouint, unsigned int)
82STRTO_H(strtoll, long long)
83STRTO_H(strtoull, unsigned long long)
84
85/**
86 * bch_hprint - formats @v to human readable string for sysfs.
87 * @buf: the (at least 8 byte) buffer to format the result into.
88 * @v: signed 64 bit integer
89 *
90 * Returns the number of bytes used by format.
91 */
92ssize_t bch_hprint(char *buf, int64_t v)
93{
94	static const char units[] = "?kMGTPEZY";
95	int u = 0, t;
96
97	uint64_t q;
98
99	if (v < 0)
100		q = -v;
101	else
102		q = v;
103
104	/* For as long as the number is more than 3 digits, but at least
105	 * once, shift right / divide by 1024.  Keep the remainder for
106	 * a digit after the decimal point.
107	 */
108	do {
109		u++;
110
111		t = q & ~(~0 << 10);
112		q >>= 10;
113	} while (q >= 1000);
114
115	if (v < 0)
116		/* '-', up to 3 digits, '.', 1 digit, 1 character, null;
117		 * yields 8 bytes.
118		 */
119		return sprintf(buf, "-%llu.%i%c", q, t * 10 / 1024, units[u]);
120	else
121		return sprintf(buf, "%llu.%i%c", q, t * 10 / 1024, units[u]);
122}
123
124bool bch_is_zero(const char *p, size_t n)
125{
126	size_t i;
127
128	for (i = 0; i < n; i++)
129		if (p[i])
130			return false;
131	return true;
132}
133
134int bch_parse_uuid(const char *s, char *uuid)
135{
136	size_t i, j, x;
137
138	memset(uuid, 0, 16);
139
140	for (i = 0, j = 0;
141	     i < strspn(s, "-0123456789:ABCDEFabcdef") && j < 32;
142	     i++) {
143		x = s[i] | 32;
144
145		switch (x) {
146		case '0'...'9':
147			x -= '0';
148			break;
149		case 'a'...'f':
150			x -= 'a' - 10;
151			break;
152		default:
153			continue;
154		}
155
156		if (!(j & 1))
157			x <<= 4;
158		uuid[j++ >> 1] |= x;
159	}
160	return i;
161}
162
163void bch_time_stats_update(struct time_stats *stats, uint64_t start_time)
164{
165	uint64_t now, duration, last;
166
167	spin_lock(&stats->lock);
168
169	now		= local_clock();
170	duration	= time_after64(now, start_time)
171		? now - start_time : 0;
172	last		= time_after64(now, stats->last)
173		? now - stats->last : 0;
174
175	stats->max_duration = max(stats->max_duration, duration);
176
177	if (stats->last) {
178		ewma_add(stats->average_duration, duration, 8, 8);
179
180		if (stats->average_frequency)
181			ewma_add(stats->average_frequency, last, 8, 8);
182		else
183			stats->average_frequency  = last << 8;
184	} else {
185		stats->average_duration  = duration << 8;
186	}
187
188	stats->last = now ?: 1;
189
190	spin_unlock(&stats->lock);
191}
192
193/**
194 * bch_next_delay() - update ratelimiting statistics and calculate next delay
195 * @d: the struct bch_ratelimit to update
196 * @done: the amount of work done, in arbitrary units
197 *
198 * Increment @d by the amount of work done, and return how long to delay in
199 * jiffies until the next time to do some work.
200 */
201uint64_t bch_next_delay(struct bch_ratelimit *d, uint64_t done)
202{
203	uint64_t now = local_clock();
204
205	d->next += div_u64(done * NSEC_PER_SEC, atomic_long_read(&d->rate));
206
207	/* Bound the time.  Don't let us fall further than 2 seconds behind
208	 * (this prevents unnecessary backlog that would make it impossible
209	 * to catch up).  If we're ahead of the desired writeback rate,
210	 * don't let us sleep more than 2.5 seconds (so we can notice/respond
211	 * if the control system tells us to speed up!).
212	 */
213	if (time_before64(now + NSEC_PER_SEC * 5LLU / 2LLU, d->next))
214		d->next = now + NSEC_PER_SEC * 5LLU / 2LLU;
215
216	if (time_after64(now - NSEC_PER_SEC * 2, d->next))
217		d->next = now - NSEC_PER_SEC * 2;
218
219	return time_after64(d->next, now)
220		? div_u64(d->next - now, NSEC_PER_SEC / HZ)
221		: 0;
222}
223
224/*
225 * Generally it isn't good to access .bi_io_vec and .bi_vcnt directly,
226 * the preferred way is bio_add_page, but in this case, bch_bio_map()
227 * supposes that the bvec table is empty, so it is safe to access
228 * .bi_vcnt & .bi_io_vec in this way even after multipage bvec is
229 * supported.
230 */
231void bch_bio_map(struct bio *bio, void *base)
232{
233	size_t size = bio->bi_iter.bi_size;
234	struct bio_vec *bv = bio->bi_io_vec;
235
236	BUG_ON(!bio->bi_iter.bi_size);
237	BUG_ON(bio->bi_vcnt);
238
239	bv->bv_offset = base ? offset_in_page(base) : 0;
240	goto start;
241
242	for (; size; bio->bi_vcnt++, bv++) {
243		bv->bv_offset	= 0;
244start:		bv->bv_len	= min_t(size_t, PAGE_SIZE - bv->bv_offset,
245					size);
246		if (base) {
247			bv->bv_page = is_vmalloc_addr(base)
248				? vmalloc_to_page(base)
249				: virt_to_page(base);
250
251			base += bv->bv_len;
252		}
253
254		size -= bv->bv_len;
255	}
256}
257
258/**
259 * bch_bio_alloc_pages - allocates a single page for each bvec in a bio
260 * @bio: bio to allocate pages for
261 * @gfp_mask: flags for allocation
262 *
263 * Allocates pages up to @bio->bi_vcnt.
264 *
265 * Returns 0 on success, -ENOMEM on failure. On failure, any allocated pages are
266 * freed.
267 */
268int bch_bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
269{
270	int i;
271	struct bio_vec *bv;
272
273	/*
274	 * This is called on freshly new bio, so it is safe to access the
275	 * bvec table directly.
276	 */
277	for (i = 0, bv = bio->bi_io_vec; i < bio->bi_vcnt; bv++, i++) {
278		bv->bv_page = alloc_page(gfp_mask);
279		if (!bv->bv_page) {
280			while (--bv >= bio->bi_io_vec)
281				__free_page(bv->bv_page);
282			return -ENOMEM;
283		}
284	}
285
286	return 0;
287}
288