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 }