Merge tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block
[sfrench/cifs-2.6.git] / drivers / md / bcache / util.c
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)                                     \
24 int 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                 /* fall through */                              \
37         case 'e':                                               \
38                 u++;                                            \
39                 /* fall through */                              \
40         case 'p':                                               \
41                 u++;                                            \
42                 /* fall through */                              \
43         case 't':                                               \
44                 u++;                                            \
45                 /* fall through */                              \
46         case 'g':                                               \
47                 u++;                                            \
48                 /* fall through */                              \
49         case 'm':                                               \
50                 u++;                                            \
51                 /* fall through */                              \
52         case 'k':                                               \
53                 u++;                                            \
54                 if (e++ == cp)                                  \
55                         return -EINVAL;                         \
56                 /* fall through */                              \
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
80 STRTO_H(strtoint, int)
81 STRTO_H(strtouint, unsigned int)
82 STRTO_H(strtoll, long long)
83 STRTO_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  */
92 ssize_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
124 bool 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
134 int 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
163 void 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  */
201 uint64_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  */
231 void 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;
244 start:          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  */
268 int bch_bio_alloc_pages(struct bio *bio, gfp_t gfp_mask)
269 {
270         int i;
271         struct bio_vec *bv;
272
273         bio_for_each_segment_all(bv, bio, i) {
274                 bv->bv_page = alloc_page(gfp_mask);
275                 if (!bv->bv_page) {
276                         while (--bv >= bio->bi_io_vec)
277                                 __free_page(bv->bv_page);
278                         return -ENOMEM;
279                 }
280         }
281
282         return 0;
283 }