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, bio->bi_inline_vecs, bucket_pages(c));
  28
  29         return bio;
  30 }
  31
  32 void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
  33 {
  34         struct bbio *b = container_of(bio, struct bbio, bio);
  35
  36         bio->bi_iter.bi_sector  = PTR_OFFSET(&b->key, 0);
  37         bio->bi_bdev            = PTR_CACHE(c, &b->key, 0)->bdev;
  38
  39         b->submit_time_us = local_clock_us();
  40         closure_bio_submit(bio, bio->bi_private);
  41 }
  42
  43 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
  44                      struct bkey *k, unsigned ptr)
  45 {
  46         struct bbio *b = container_of(bio, struct bbio, bio);
  47         bch_bkey_copy_single_ptr(&b->key, k, ptr);
  48         __bch_submit_bbio(bio, c);
  49 }
  50
  51 /* IO errors */
  52
  53 void bch_count_io_errors(struct cache *ca, int error, const char *m)
  54 {
  55         /*
  56          * The halflife of an error is:
  57          * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
  58          */
  59
  60         if (ca->set->error_decay) {
  61                 unsigned count = atomic_inc_return(&ca->io_count);
  62
  63                 while (count > ca->set->error_decay) {
  64                         unsigned errors;
  65                         unsigned old = count;
  66                         unsigned new = count - ca->set->error_decay;
  67
  68                         /*
  69                          * First we subtract refresh from count; each time we
  70                          * succesfully do so, we rescale the errors once:
  71                          */
  72
  73                         count = atomic_cmpxchg(&ca->io_count, old, new);
  74
  75                         if (count == old) {
  76                                 count = new;
  77
  78                                 errors = atomic_read(&ca->io_errors);
  79                                 do {
  80                                         old = errors;
  81                                         new = ((uint64_t) errors * 127) / 128;
  82                                         errors = atomic_cmpxchg(&ca->io_errors,
  83                                                                 old, new);
  84                                 } while (old != errors);
  85                         }
  86                 }
  87         }
  88
  89         if (error) {
  90                 char buf[BDEVNAME_SIZE];
  91                 unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
  92                                                     &ca->io_errors);
  93                 errors >>= IO_ERROR_SHIFT;
  94
  95                 if (errors < ca->set->error_limit)
  96                         pr_err("%s: IO error on %s, recovering",
  97                                bdevname(ca->bdev, buf), m);
  98                 else
  99                         bch_cache_set_error(ca->set,
 100                                             "%s: too many IO errors %s",
 101                                             bdevname(ca->bdev, buf), m);
 102         }
 103 }
 104
 105 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 106                               int error, const char *m)
 107 {
 108         struct bbio *b = container_of(bio, struct bbio, bio);
 109         struct cache *ca = PTR_CACHE(c, &b->key, 0);
 110
 111         unsigned threshold = op_is_write(bio_op(bio))
 112                 ? c->congested_write_threshold_us
 113                 : c->congested_read_threshold_us;
 114
 115         if (threshold) {
 116                 unsigned t = local_clock_us();
 117
 118                 int us = t - b->submit_time_us;
 119                 int congested = atomic_read(&c->congested);
 120
 121                 if (us > (int) threshold) {
 122                         int ms = us / 1024;
 123                         c->congested_last_us = t;
 124
 125                         ms = min(ms, CONGESTED_MAX + congested);
 126                         atomic_sub(ms, &c->congested);
 127                 } else if (congested < 0)
 128                         atomic_inc(&c->congested);
 129         }
 130
 131         bch_count_io_errors(ca, error, m);
 132 }
 133
 134 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 135                     int error, const char *m)
 136 {
 137         struct closure *cl = bio->bi_private;
 138
 139         bch_bbio_count_io_errors(c, bio, error, m);
 140         bio_put(bio);
 141         closure_put(cl);
 142 }