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
  16 void 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
  22 struct 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
  34 void __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
  45 void 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
  55 void 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
 107 void 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
 136 void 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 }