LXR linux/drivers/md/bcache/io.c

   1/*
   2 * Some low level IO code, and hacks for various block layer limitations
   3 *
   4 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
   5 * Copyright 2012 Google, Inc.
   6 */
   7
   8#include "bcache.h"
   9#include "bset.h"
  10#include "debug.h"
  11
  12#include <linux/blkdev.h>
  13
  14/* Bios with headers */
  15
  16void bch_bbio_free(struct bio *bio, struct cache_set *c)
  17{
  18        struct bbio *b = container_of(bio, struct bbio, bio);
  19        mempool_free(b, c->bio_meta);
  20}
  21
  22struct bio *bch_bbio_alloc(struct cache_set *c)
  23{
  24        struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO);
  25        struct bio *bio = &b->bio;
  26
  27        bio_init(bio);
  28        bio->bi_max_vecs         = bucket_pages(c);
  29        bio->bi_io_vec           = bio->bi_inline_vecs;
  30
  31        return bio;
  32}
  33
  34void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
  35{
  36        struct bbio *b = container_of(bio, struct bbio, bio);
  37
  38        bio->bi_iter.bi_sector  = PTR_OFFSET(&b->key, 0);
  39        bio->bi_bdev            = PTR_CACHE(c, &b->key, 0)->bdev;
  40
  41        b->submit_time_us = local_clock_us();
  42        closure_bio_submit(bio, bio->bi_private);
  43}
  44
  45void bch_submit_bbio(struct bio *bio, struct cache_set *c,
  46                     struct bkey *k, unsigned ptr)
  47{
  48        struct bbio *b = container_of(bio, struct bbio, bio);
  49        bch_bkey_copy_single_ptr(&b->key, k, ptr);
  50        __bch_submit_bbio(bio, c);
  51}
  52
  53/* IO errors */
  54
  55void bch_count_io_errors(struct cache *ca, int error, const char *m)
  56{
  57        /*
  58         * The halflife of an error is:
  59         * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
  60         */
  61
  62        if (ca->set->error_decay) {
  63                unsigned count = atomic_inc_return(&ca->io_count);
  64
  65                while (count > ca->set->error_decay) {
  66                        unsigned errors;
  67                        unsigned old = count;
  68                        unsigned new = count - ca->set->error_decay;
  69
  70                        /*
  71                         * First we subtract refresh from count; each time we
  72                         * succesfully do so, we rescale the errors once:
  73                         */
  74
  75                        count = atomic_cmpxchg(&ca->io_count, old, new);
  76
  77                        if (count == old) {
  78                                count = new;
  79
  80                                errors = atomic_read(&ca->io_errors);
  81                                do {
  82                                        old = errors;
  83                                        new = ((uint64_t) errors * 127) / 128;
  84                                        errors = atomic_cmpxchg(&ca->io_errors,
  85                                                                old, new);
  86                                } while (old != errors);
  87                        }
  88                }
  89        }
  90
  91        if (error) {
  92                char buf[BDEVNAME_SIZE];
  93                unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
  94                                                    &ca->io_errors);
  95                errors >>= IO_ERROR_SHIFT;
  96
  97                if (errors < ca->set->error_limit)
  98                        pr_err("%s: IO error on %s, recovering",
  99                               bdevname(ca->bdev, buf), m);
 100                else
 101                        bch_cache_set_error(ca->set,
 102                                            "%s: too many IO errors %s",
 103                                            bdevname(ca->bdev, buf), m);
 104        }
 105}
 106
 107void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 108                              int error, const char *m)
 109{
 110        struct bbio *b = container_of(bio, struct bbio, bio);
 111        struct cache *ca = PTR_CACHE(c, &b->key, 0);
 112
 113        unsigned threshold = op_is_write(bio_op(bio))
 114                ? c->congested_write_threshold_us
 115                : c->congested_read_threshold_us;
 116
 117        if (threshold) {
 118                unsigned t = local_clock_us();
 119
 120                int us = t - b->submit_time_us;
 121                int congested = atomic_read(&c->congested);
 122
 123                if (us > (int) threshold) {
 124                        int ms = us / 1024;
 125                        c->congested_last_us = t;
 126
 127                        ms = min(ms, CONGESTED_MAX + congested);
 128                        atomic_sub(ms, &c->congested);
 129                } else if (congested < 0)
 130                        atomic_inc(&c->congested);
 131        }
 132
 133        bch_count_io_errors(ca, error, m);
 134}
 135
 136void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 137                    int error, const char *m)
 138{
 139        struct closure *cl = bio->bi_private;
 140
 141        bch_bbio_count_io_errors(c, bio, error, m);
 142        bio_put(bio);
 143        closure_put(cl);
 144}
 145