LXR linux/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
  17void 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
  23struct 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
  33void __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
  44void 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 */
  53void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
  54{
  55        unsigned errors;
  56
  57        WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
  58
  59        errors = atomic_add_return(1, &dc->io_errors);
  60        if (errors < dc->error_limit)
  61                pr_err("%s: IO error on backing device, unrecoverable",
  62                        dc->backing_dev_name);
  63        else
  64                bch_cached_dev_error(dc);
  65}
  66
  67void bch_count_io_errors(struct cache *ca,
  68                         blk_status_t error,
  69                         int is_read,
  70                         const char *m)
  71{
  72        /*
  73         * The halflife of an error is:
  74         * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
  75         */
  76
  77        if (ca->set->error_decay) {
  78                unsigned count = atomic_inc_return(&ca->io_count);
  79
  80                while (count > ca->set->error_decay) {
  81                        unsigned errors;
  82                        unsigned old = count;
  83                        unsigned new = count - ca->set->error_decay;
  84
  85                        /*
  86                         * First we subtract refresh from count; each time we
  87                         * succesfully do so, we rescale the errors once:
  88                         */
  89
  90                        count = atomic_cmpxchg(&ca->io_count, old, new);
  91
  92                        if (count == old) {
  93                                count = new;
  94
  95                                errors = atomic_read(&ca->io_errors);
  96                                do {
  97                                        old = errors;
  98                                        new = ((uint64_t) errors * 127) / 128;
  99                                        errors = atomic_cmpxchg(&ca->io_errors,
 100                                                                old, new);
 101                                } while (old != errors);
 102                        }
 103                }
 104        }
 105
 106        if (error) {
 107                unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
 108                                                    &ca->io_errors);
 109                errors >>= IO_ERROR_SHIFT;
 110
 111                if (errors < ca->set->error_limit)
 112                        pr_err("%s: IO error on %s%s",
 113                               ca->cache_dev_name, m,
 114                               is_read ? ", recovering." : ".");
 115                else
 116                        bch_cache_set_error(ca->set,
 117                                            "%s: too many IO errors %s",
 118                                            ca->cache_dev_name, m);
 119        }
 120}
 121
 122void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 123                              blk_status_t error, const char *m)
 124{
 125        struct bbio *b = container_of(bio, struct bbio, bio);
 126        struct cache *ca = PTR_CACHE(c, &b->key, 0);
 127        int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
 128
 129        unsigned threshold = op_is_write(bio_op(bio))
 130                ? c->congested_write_threshold_us
 131                : c->congested_read_threshold_us;
 132
 133        if (threshold) {
 134                unsigned t = local_clock_us();
 135
 136                int us = t - b->submit_time_us;
 137                int congested = atomic_read(&c->congested);
 138
 139                if (us > (int) threshold) {
 140                        int ms = us / 1024;
 141                        c->congested_last_us = t;
 142
 143                        ms = min(ms, CONGESTED_MAX + congested);
 144                        atomic_sub(ms, &c->congested);
 145                } else if (congested < 0)
 146                        atomic_inc(&c->congested);
 147        }
 148
 149        bch_count_io_errors(ca, error, is_read, m);
 150}
 151
 152void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 153                    blk_status_t error, const char *m)
 154{
 155        struct closure *cl = bio->bi_private;
 156
 157        bch_bbio_count_io_errors(c, bio, error, m);
 158        bio_put(bio);
 159        closure_put(cl);
 160}
 161