drivers/md/bcache/io.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Some low level IO code, and hacks for various block layer limitations
   4  *
   5  * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
   6  * Copyright 2012 Google, Inc.
   7  */
   8
   9 #include "bcache.h"
  10 #include "bset.h"
  11 #include "debug.h"
  12
  13 #include <linux/blkdev.h>
  14
  15 /* Bios with headers */
  16
  17 void bch_bbio_free(struct bio *bio, struct cache_set *c)
  18 {
  19         struct bbio *b = container_of(bio, struct bbio, bio);
  20         mempool_free(b, c->bio_meta);
  21 }
  22
  23 struct bio *bch_bbio_alloc(struct cache_set *c)
  24 {
  25         struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO);
  26         struct bio *bio = &b->bio;
  27
  28         bio_init(bio, bio->bi_inline_vecs, bucket_pages(c));
  29
  30         return bio;
  31 }
  32
  33 void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
  34 {
  35         struct bbio *b = container_of(bio, struct bbio, bio);
  36
  37         bio->bi_iter.bi_sector  = PTR_OFFSET(&b->key, 0);
  38         bio_set_dev(bio, PTR_CACHE(c, &b->key, 0)->bdev);
  39
  40         b->submit_time_us = local_clock_us();
  41         closure_bio_submit(bio, bio->bi_private);
  42 }
  43
  44 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
  45                      struct bkey *k, unsigned ptr)
  46 {
  47         struct bbio *b = container_of(bio, struct bbio, bio);
  48         bch_bkey_copy_single_ptr(&b->key, k, ptr);
  49         __bch_submit_bbio(bio, c);
  50 }
  51
  52 /* IO errors */
  53
  54 void bch_count_io_errors(struct cache *ca, blk_status_t error, const char *m)
  55 {
  56         /*
  57          * The halflife of an error is:
  58          * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
  59          */
  60
  61         if (ca->set->error_decay) {
  62                 unsigned count = atomic_inc_return(&ca->io_count);
  63
  64                 while (count > ca->set->error_decay) {
  65                         unsigned errors;
  66                         unsigned old = count;
  67                         unsigned new = count - ca->set->error_decay;
  68
  69                         /*
  70                          * First we subtract refresh from count; each time we
  71                          * succesfully do so, we rescale the errors once:
  72                          */
  73
  74                         count = atomic_cmpxchg(&ca->io_count, old, new);
  75
  76                         if (count == old) {
  77                                 count = new;
  78
  79                                 errors = atomic_read(&ca->io_errors);
  80                                 do {
  81                                         old = errors;
  82                                         new = ((uint64_t) errors * 127) / 128;
  83                                         errors = atomic_cmpxchg(&ca->io_errors,
  84                                                                 old, new);
  85                                 } while (old != errors);
  86                         }
  87                 }
  88         }
  89
  90         if (error) {
  91                 char buf[BDEVNAME_SIZE];
  92                 unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
  93                                                     &ca->io_errors);
  94                 errors >>= IO_ERROR_SHIFT;
  95
  96                 if (errors < ca->set->error_limit)
  97                         pr_err("%s: IO error on %s, recovering",
  98                                bdevname(ca->bdev, buf), m);
  99                 else
 100                         bch_cache_set_error(ca->set,
 101                                             "%s: too many IO errors %s",
 102                                             bdevname(ca->bdev, buf), m);
 103         }
 104 }
 105
 106 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 107                               blk_status_t error, const char *m)
 108 {
 109         struct bbio *b = container_of(bio, struct bbio, bio);
 110         struct cache *ca = PTR_CACHE(c, &b->key, 0);
 111
 112         unsigned threshold = op_is_write(bio_op(bio))
 113                 ? c->congested_write_threshold_us
 114                 : c->congested_read_threshold_us;
 115
 116         if (threshold) {
 117                 unsigned t = local_clock_us();
 118
 119                 int us = t - b->submit_time_us;
 120                 int congested = atomic_read(&c->congested);
 121
 122                 if (us > (int) threshold) {
 123                         int ms = us / 1024;
 124                         c->congested_last_us = t;
 125
 126                         ms = min(ms, CONGESTED_MAX + congested);
 127                         atomic_sub(ms, &c->congested);
 128                 } else if (congested < 0)
 129                         atomic_inc(&c->congested);
 130         }
 131
 132         bch_count_io_errors(ca, error, m);
 133 }
 134
 135 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 136                     blk_status_t error, const char *m)
 137 {
 138         struct closure *cl = bio->bi_private;
 139
 140         bch_bbio_count_io_errors(c, bio, error, m);
 141         bio_put(bio);
 142         closure_put(cl);
 143 }