linux/drivers/md/bcache/util.c
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   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
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