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 static unsigned bch_bio_max_sectors(struct bio *bio)
  15 {
  16         struct request_queue *q = bdev_get_queue(bio->bi_bdev);
  17         struct bio_vec bv;
  18         struct bvec_iter iter;
  19         unsigned ret = 0, seg = 0;
  20
  21         if (bio->bi_rw & REQ_DISCARD)
  22                 return min(bio_sectors(bio), q->limits.max_discard_sectors);
  23
  24         bio_for_each_segment(bv, bio, iter) {
  25                 struct bvec_merge_data bvm = {
  26                         .bi_bdev        = bio->bi_bdev,
  27                         .bi_sector      = bio->bi_iter.bi_sector,
  28                         .bi_size        = ret << 9,
  29                         .bi_rw          = bio->bi_rw,
  30                 };
  31
  32                 if (seg == min_t(unsigned, BIO_MAX_PAGES,
  33                                  queue_max_segments(q)))
  34                         break;
  35
  36                 if (q->merge_bvec_fn &&
  37                     q->merge_bvec_fn(q, &bvm, &bv) < (int) bv.bv_len)
  38                         break;
  39
  40                 seg++;
  41                 ret += bv.bv_len >> 9;
  42         }
  43
  44         ret = min(ret, queue_max_sectors(q));
  45
  46         WARN_ON(!ret);
  47         ret = max_t(int, ret, bio_iovec(bio).bv_len >> 9);
  48
  49         return ret;
  50 }
  51
  52 static void bch_bio_submit_split_done(struct closure *cl)
  53 {
  54         struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
  55
  56         s->bio->bi_end_io = s->bi_end_io;
  57         s->bio->bi_private = s->bi_private;
  58         bio_endio_nodec(s->bio, 0);
  59
  60         closure_debug_destroy(&s->cl);
  61         mempool_free(s, s->p->bio_split_hook);
  62 }
  63
  64 static void bch_bio_submit_split_endio(struct bio *bio, int error)
  65 {
  66         struct closure *cl = bio->bi_private;
  67         struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl);
  68
  69         if (error)
  70                 clear_bit(BIO_UPTODATE, &s->bio->bi_flags);
  71
  72         bio_put(bio);
  73         closure_put(cl);
  74 }
  75
  76 void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p)
  77 {
  78         struct bio_split_hook *s;
  79         struct bio *n;
  80
  81         if (!bio_has_data(bio) && !(bio->bi_rw & REQ_DISCARD))
  82                 goto submit;
  83
  84         if (bio_sectors(bio) <= bch_bio_max_sectors(bio))
  85                 goto submit;
  86
  87         s = mempool_alloc(p->bio_split_hook, GFP_NOIO);
  88         closure_init(&s->cl, NULL);
  89
  90         s->bio          = bio;
  91         s->p            = p;
  92         s->bi_end_io    = bio->bi_end_io;
  93         s->bi_private   = bio->bi_private;
  94         bio_get(bio);
  95
  96         do {
  97                 n = bio_next_split(bio, bch_bio_max_sectors(bio),
  98                                    GFP_NOIO, s->p->bio_split);
  99
 100                 n->bi_end_io    = bch_bio_submit_split_endio;
 101                 n->bi_private   = &s->cl;
 102
 103                 closure_get(&s->cl);
 104                 generic_make_request(n);
 105         } while (n != bio);
 106
 107         continue_at(&s->cl, bch_bio_submit_split_done, NULL);
 108 submit:
 109         generic_make_request(bio);
 110 }
 111
 112 /* Bios with headers */
 113
 114 void bch_bbio_free(struct bio *bio, struct cache_set *c)
 115 {
 116         struct bbio *b = container_of(bio, struct bbio, bio);
 117         mempool_free(b, c->bio_meta);
 118 }
 119
 120 struct bio *bch_bbio_alloc(struct cache_set *c)
 121 {
 122         struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO);
 123         struct bio *bio = &b->bio;
 124
 125         bio_init(bio);
 126         bio->bi_flags           |= BIO_POOL_NONE << BIO_POOL_OFFSET;
 127         bio->bi_max_vecs         = bucket_pages(c);
 128         bio->bi_io_vec           = bio->bi_inline_vecs;
 129
 130         return bio;
 131 }
 132
 133 void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
 134 {
 135         struct bbio *b = container_of(bio, struct bbio, bio);
 136
 137         bio->bi_iter.bi_sector  = PTR_OFFSET(&b->key, 0);
 138         bio->bi_bdev            = PTR_CACHE(c, &b->key, 0)->bdev;
 139
 140         b->submit_time_us = local_clock_us();
 141         closure_bio_submit(bio, bio->bi_private, PTR_CACHE(c, &b->key, 0));
 142 }
 143
 144 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
 145                      struct bkey *k, unsigned ptr)
 146 {
 147         struct bbio *b = container_of(bio, struct bbio, bio);
 148         bch_bkey_copy_single_ptr(&b->key, k, ptr);
 149         __bch_submit_bbio(bio, c);
 150 }
 151
 152 /* IO errors */
 153
 154 void bch_count_io_errors(struct cache *ca, int error, const char *m)
 155 {
 156         /*
 157          * The halflife of an error is:
 158          * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
 159          */
 160
 161         if (ca->set->error_decay) {
 162                 unsigned count = atomic_inc_return(&ca->io_count);
 163
 164                 while (count > ca->set->error_decay) {
 165                         unsigned errors;
 166                         unsigned old = count;
 167                         unsigned new = count - ca->set->error_decay;
 168
 169                         /*
 170                          * First we subtract refresh from count; each time we
 171                          * succesfully do so, we rescale the errors once:
 172                          */
 173
 174                         count = atomic_cmpxchg(&ca->io_count, old, new);
 175
 176                         if (count == old) {
 177                                 count = new;
 178
 179                                 errors = atomic_read(&ca->io_errors);
 180                                 do {
 181                                         old = errors;
 182                                         new = ((uint64_t) errors * 127) / 128;
 183                                         errors = atomic_cmpxchg(&ca->io_errors,
 184                                                                 old, new);
 185                                 } while (old != errors);
 186                         }
 187                 }
 188         }
 189
 190         if (error) {
 191                 char buf[BDEVNAME_SIZE];
 192                 unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
 193                                                     &ca->io_errors);
 194                 errors >>= IO_ERROR_SHIFT;
 195
 196                 if (errors < ca->set->error_limit)
 197                         pr_err("%s: IO error on %s, recovering",
 198                                bdevname(ca->bdev, buf), m);
 199                 else
 200                         bch_cache_set_error(ca->set,
 201                                             "%s: too many IO errors %s",
 202                                             bdevname(ca->bdev, buf), m);
 203         }
 204 }
 205
 206 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
 207                               int error, const char *m)
 208 {
 209         struct bbio *b = container_of(bio, struct bbio, bio);
 210         struct cache *ca = PTR_CACHE(c, &b->key, 0);
 211
 212         unsigned threshold = bio->bi_rw & REQ_WRITE
 213                 ? c->congested_write_threshold_us
 214                 : c->congested_read_threshold_us;
 215
 216         if (threshold) {
 217                 unsigned t = local_clock_us();
 218
 219                 int us = t - b->submit_time_us;
 220                 int congested = atomic_read(&c->congested);
 221
 222                 if (us > (int) threshold) {
 223                         int ms = us / 1024;
 224                         c->congested_last_us = t;
 225
 226                         ms = min(ms, CONGESTED_MAX + congested);
 227                         atomic_sub(ms, &c->congested);
 228                 } else if (congested < 0)
 229                         atomic_inc(&c->congested);
 230         }
 231
 232         bch_count_io_errors(ca, error, m);
 233 }
 234
 235 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
 236                     int error, const char *m)
 237 {
 238         struct closure *cl = bio->bi_private;
 239
 240         bch_bbio_count_io_errors(c, bio, error, m);
 241         bio_put(bio);
 242         closure_put(cl);
 243 }