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
  17 void bch_bbio_free(struct bio *bio, struct cache_set *c)
  18 {
  19         struct bbio *b = container_of(bio, struct bbio, bio);
  20
  21         mempool_free(b, &c->bio_meta);
  22 }
  23
  24 struct bio *bch_bbio_alloc(struct cache_set *c)
  25 {
  26         struct bbio *b = mempool_alloc(&c->bio_meta, GFP_NOIO);
  27         struct bio *bio = &b->bio;
  28
  29         bio_init(bio, bio->bi_inline_vecs, bucket_pages(c));
  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_set_dev(bio, PTR_CACHE(c, &b->key, 0)->bdev);
  40
  41         b->submit_time_us = local_clock_us();
  42         closure_bio_submit(c, bio, bio->bi_private);
  43 }
  44
  45 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
  46                      struct bkey *k, unsigned int ptr)
  47 {
  48         struct bbio *b = container_of(bio, struct bbio, bio);
  49
  50         bch_bkey_copy_single_ptr(&b->key, k, ptr);
  51         __bch_submit_bbio(bio, c);
  52 }
  53
  54 /* IO errors */
  55 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
  56 {
  57         unsigned int errors;
  58
  59         WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
  60
  61         /*
  62          * Read-ahead requests on a degrading and recovering md raid
  63          * (e.g. raid6) device might be failured immediately by md
  64          * raid code, which is not a real hardware media failure. So
  65          * we shouldn't count failed REQ_RAHEAD bio to dc->io_errors.
  66          */
  67         if (bio->bi_opf & REQ_RAHEAD) {
  68                 pr_warn_ratelimited("%s: Read-ahead I/O failed on backing device, ignore",
  69                                     dc->backing_dev_name);
  70                 return;
  71         }
  72
  73         errors = atomic_add_return(1, &dc->io_errors);
  74         if (errors < dc->error_limit)
  75                 pr_err("%s: IO error on backing device, unrecoverable",
  76                         dc->backing_dev_name);
  77         else
  78                 bch_cached_dev_error(dc);
  79 }
  80
  81 void bch_count_io_errors(struct cache *ca,
  82                          blk_status_t error,
  83                          int is_read,
  84                          const char *m)
  85 {
  86         /*
  87          * The halflife of an error is:
  88          * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
  89          */
  90
  91         if (ca->set->error_decay) {
  92                 unsigned int count = atomic_inc_return(&ca->io_count);
  93
  94                 while (count > ca->set->error_decay) {
  95                         unsigned int errors;
  96                         unsigned int old = count;
  97                         unsigned int new = count - ca->set->error_decay;
  98
  99                         /*
 100                          * First we subtract refresh from count; each time we
 101                          * successfully do so, we rescale the errors once:
 102                          */
 103
 104                         count = atomic_cmpxchg(&ca->io_count, old, new);
 105
 106                         if (count == old) {
 107                                 count = new;
 108
 109                                 errors = atomic_read(&ca->io_errors);
 110                                 do {
 111                                         old = errors;
 112                                         new = ((uint64_t) errors * 127) / 128;
 113                                         errors = atomic_cmpxchg(&ca->io_errors,
 114                                                                 old, new);
 115                                 } while (old != errors);
 116                         }
 117                 }
 118         }
 119
 120         if (error) {
 121                 unsigned int errors = atomic_add_return(1 << IO_ERROR_SHIFT,
 122                                                     &ca->io_errors);
 123                 errors >>= IO_ERROR_SHIFT;
 124
 125                 if (errors < ca->set->error_limit)
 126                         pr_err("%s: IO error on %s%s",
 127                                ca->cache_dev_name, m,
 128                                is_read ? ", recovering." : ".");
 129                 else
 130                         bch_cache_set_error(ca->set,
 131                                             "%s: too many IO errors %s",
 132                                             ca->cache_dev_name, m);
 133         }
 134 }
 135
 136 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 137                               blk_status_t error, const char *m)
 138 {
 139         struct bbio *b = container_of(bio, struct bbio, bio);
 140         struct cache *ca = PTR_CACHE(c, &b->key, 0);
 141         int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
 142
 143         unsigned int threshold = op_is_write(bio_op(bio))
 144                 ? c->congested_write_threshold_us
 145                 : c->congested_read_threshold_us;
 146
 147         if (threshold) {
 148                 unsigned int t = local_clock_us();
 149                 int us = t - b->submit_time_us;
 150                 int congested = atomic_read(&c->congested);
 151
 152                 if (us > (int) threshold) {
 153                         int ms = us / 1024;
 154
 155                         c->congested_last_us = t;
 156
 157                         ms = min(ms, CONGESTED_MAX + congested);
 158                         atomic_sub(ms, &c->congested);
 159                 } else if (congested < 0)
 160                         atomic_inc(&c->congested);
 161         }
 162
 163         bch_count_io_errors(ca, error, is_read, m);
 164 }
 165
 166 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 167                     blk_status_t error, const char *m)
 168 {
 169         struct closure *cl = bio->bi_private;
 170
 171         bch_bbio_count_io_errors(c, bio, error, m);
 172         bio_put(bio);
 173         closure_put(cl);
 174 }