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 } 244