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(c, 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 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
  54 {
  55         char buf[BDEVNAME_SIZE];
  56         unsigned errors;
  57
  58         WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
  59
  60         errors = atomic_add_return(1, &dc->io_errors);
  61         if (errors < dc->error_limit)
  62                 pr_err("%s: IO error on backing device, unrecoverable",
  63                         bio_devname(bio, buf));
  64         else
  65                 bch_cached_dev_error(dc);
  66 }
  67
  68 void bch_count_io_errors(struct cache *ca,
  69                          blk_status_t error,
  70                          int is_read,
  71                          const char *m)
  72 {
  73         /*
  74          * The halflife of an error is:
  75          * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
  76          */
  77
  78         if (ca->set->error_decay) {
  79                 unsigned count = atomic_inc_return(&ca->io_count);
  80
  81                 while (count > ca->set->error_decay) {
  82                         unsigned errors;
  83                         unsigned old = count;
  84                         unsigned new = count - ca->set->error_decay;
  85
  86                         /*
  87                          * First we subtract refresh from count; each time we
  88                          * succesfully do so, we rescale the errors once:
  89                          */
  90
  91                         count = atomic_cmpxchg(&ca->io_count, old, new);
  92
  93                         if (count == old) {
  94                                 count = new;
  95
  96                                 errors = atomic_read(&ca->io_errors);
  97                                 do {
  98                                         old = errors;
  99                                         new = ((uint64_t) errors * 127) / 128;
 100                                         errors = atomic_cmpxchg(&ca->io_errors,
 101                                                                 old, new);
 102                                 } while (old != errors);
 103                         }
 104                 }
 105         }
 106
 107         if (error) {
 108                 char buf[BDEVNAME_SIZE];
 109                 unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
 110                                                     &ca->io_errors);
 111                 errors >>= IO_ERROR_SHIFT;
 112
 113                 if (errors < ca->set->error_limit)
 114                         pr_err("%s: IO error on %s%s",
 115                                bdevname(ca->bdev, buf), m,
 116                                is_read ? ", recovering." : ".");
 117                 else
 118                         bch_cache_set_error(ca->set,
 119                                             "%s: too many IO errors %s",
 120                                             bdevname(ca->bdev, buf), m);
 121         }
 122 }
 123
 124 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 125                               blk_status_t error, const char *m)
 126 {
 127         struct bbio *b = container_of(bio, struct bbio, bio);
 128         struct cache *ca = PTR_CACHE(c, &b->key, 0);
 129         int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
 130
 131         unsigned threshold = op_is_write(bio_op(bio))
 132                 ? c->congested_write_threshold_us
 133                 : c->congested_read_threshold_us;
 134
 135         if (threshold) {
 136                 unsigned t = local_clock_us();
 137
 138                 int us = t - b->submit_time_us;
 139                 int congested = atomic_read(&c->congested);
 140
 141                 if (us > (int) threshold) {
 142                         int ms = us / 1024;
 143                         c->congested_last_us = t;
 144
 145                         ms = min(ms, CONGESTED_MAX + congested);
 146                         atomic_sub(ms, &c->congested);
 147                 } else if (congested < 0)
 148                         atomic_inc(&c->congested);
 149         }
 150
 151         bch_count_io_errors(ca, error, is_read, m);
 152 }
 153
 154 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 155                     blk_status_t error, const char *m)
 156 {
 157         struct closure *cl = bio->bi_private;
 158
 159         bch_bbio_count_io_errors(c, bio, error, m);
 160         bio_put(bio);
 161         closure_put(cl);
 162 }