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_flags           |= BIO_POOL_NONE << BIO_POOL_OFFSET;
  29         bio->bi_max_vecs         = bucket_pages(c);
  30         bio->bi_io_vec           = bio->bi_inline_vecs;
  31
  32         return bio;
  33 }
  34
  35 void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
  36 {
  37         struct bbio *b = container_of(bio, struct bbio, bio);
  38
  39         bio->bi_iter.bi_sector  = PTR_OFFSET(&b->key, 0);
  40         bio->bi_bdev            = PTR_CACHE(c, &b->key, 0)->bdev;
  41
  42         b->submit_time_us = local_clock_us();
  43         closure_bio_submit(bio, bio->bi_private);
  44 }
  45
  46 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
  47                      struct bkey *k, unsigned ptr)
  48 {
  49         struct bbio *b = container_of(bio, struct bbio, bio);
  50         bch_bkey_copy_single_ptr(&b->key, k, ptr);
  51         __bch_submit_bbio(bio, c);
  52 }
  53
  54 /* IO errors */
  55
  56 void bch_count_io_errors(struct cache *ca, int error, const char *m)
  57 {
  58         /*
  59          * The halflife of an error is:
  60          * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
  61          */
  62
  63         if (ca->set->error_decay) {
  64                 unsigned count = atomic_inc_return(&ca->io_count);
  65
  66                 while (count > ca->set->error_decay) {
  67                         unsigned errors;
  68                         unsigned old = count;
  69                         unsigned new = count - ca->set->error_decay;
  70
  71                         /*
  72                          * First we subtract refresh from count; each time we
  73                          * succesfully do so, we rescale the errors once:
  74                          */
  75
  76                         count = atomic_cmpxchg(&ca->io_count, old, new);
  77
  78                         if (count == old) {
  79                                 count = new;
  80
  81                                 errors = atomic_read(&ca->io_errors);
  82                                 do {
  83                                         old = errors;
  84                                         new = ((uint64_t) errors * 127) / 128;
  85                                         errors = atomic_cmpxchg(&ca->io_errors,
  86                                                                 old, new);
  87                                 } while (old != errors);
  88                         }
  89                 }
  90         }
  91
  92         if (error) {
  93                 char buf[BDEVNAME_SIZE];
  94                 unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
  95                                                     &ca->io_errors);
  96                 errors >>= IO_ERROR_SHIFT;
  97
  98                 if (errors < ca->set->error_limit)
  99                         pr_err("%s: IO error on %s, recovering",
 100                                bdevname(ca->bdev, buf), m);
 101                 else
 102                         bch_cache_set_error(ca->set,
 103                                             "%s: too many IO errors %s",
 104                                             bdevname(ca->bdev, buf), m);
 105         }
 106 }
 107
 108 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 109                               int error, const char *m)
 110 {
 111         struct bbio *b = container_of(bio, struct bbio, bio);
 112         struct cache *ca = PTR_CACHE(c, &b->key, 0);
 113
 114         unsigned threshold = bio->bi_rw & REQ_WRITE
 115                 ? c->congested_write_threshold_us
 116                 : c->congested_read_threshold_us;
 117
 118         if (threshold) {
 119                 unsigned t = local_clock_us();
 120
 121                 int us = t - b->submit_time_us;
 122                 int congested = atomic_read(&c->congested);
 123
 124                 if (us > (int) threshold) {
 125                         int ms = us / 1024;
 126                         c->congested_last_us = t;
 127
 128                         ms = min(ms, CONGESTED_MAX + congested);
 129                         atomic_sub(ms, &c->congested);
 130                 } else if (congested < 0)
 131                         atomic_inc(&c->congested);
 132         }
 133
 134         bch_count_io_errors(ca, error, m);
 135 }
 136
 137 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 138                     int error, const char *m)
 139 {
 140         struct closure *cl = bio->bi_private;
 141
 142         bch_bbio_count_io_errors(c, bio, error, m);
 143         bio_put(bio);
 144         closure_put(cl);
 145 }