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 static void bch_bi_idx_hack_endio(struct bio *bio, int error) 13 { 14 struct bio *p = bio->bi_private; 15 16 bio_endio(p, error); 17 bio_put(bio); 18 } 19 20 static void bch_generic_make_request_hack(struct bio *bio) 21 { 22 if (bio->bi_idx) { 23 struct bio *clone = bio_alloc(GFP_NOIO, bio_segments(bio)); 24 25 memcpy(clone->bi_io_vec, 26 bio_iovec(bio), 27 bio_segments(bio) * sizeof(struct bio_vec)); 28 29 clone->bi_sector = bio->bi_sector; 30 clone->bi_bdev = bio->bi_bdev; 31 clone->bi_rw = bio->bi_rw; 32 clone->bi_vcnt = bio_segments(bio); 33 clone->bi_size = bio->bi_size; 34 35 clone->bi_private = bio; 36 clone->bi_end_io = bch_bi_idx_hack_endio; 37 38 bio = clone; 39 } 40 41 /* 42 * Hack, since drivers that clone bios clone up to bi_max_vecs, but our 43 * bios might have had more than that (before we split them per device 44 * limitations). 45 * 46 * To be taken out once immutable bvec stuff is in. 47 */ 48 bio->bi_max_vecs = bio->bi_vcnt; 49 50 generic_make_request(bio); 51 } 52 53 /** 54 * bch_bio_split - split a bio 55 * @bio: bio to split 56 * @sectors: number of sectors to split from the front of @bio 57 * @gfp: gfp mask 58 * @bs: bio set to allocate from 59 * 60 * Allocates and returns a new bio which represents @sectors from the start of 61 * @bio, and updates @bio to represent the remaining sectors. 62 * 63 * If bio_sectors(@bio) was less than or equal to @sectors, returns @bio 64 * unchanged. 65 * 66 * The newly allocated bio will point to @bio's bi_io_vec, if the split was on a 67 * bvec boundry; it is the caller's responsibility to ensure that @bio is not 68 * freed before the split. 69 * 70 * If bch_bio_split() is running under generic_make_request(), it's not safe to 71 * allocate more than one bio from the same bio set. Therefore, if it is running 72 * under generic_make_request() it masks out __GFP_WAIT when doing the 73 * allocation. The caller must check for failure if there's any possibility of 74 * it being called from under generic_make_request(); it is then the caller's 75 * responsibility to retry from a safe context (by e.g. punting to workqueue). 76 */ 77 struct bio *bch_bio_split(struct bio *bio, int sectors, 78 gfp_t gfp, struct bio_set *bs) 79 { 80 unsigned idx = bio->bi_idx, vcnt = 0, nbytes = sectors << 9; 81 struct bio_vec *bv; 82 struct bio *ret = NULL; 83 84 BUG_ON(sectors <= 0); 85 86 /* 87 * If we're being called from underneath generic_make_request() and we 88 * already allocated any bios from this bio set, we risk deadlock if we 89 * use the mempool. So instead, we possibly fail and let the caller punt 90 * to workqueue or somesuch and retry in a safe context. 91 */ 92 if (current->bio_list) 93 gfp &= ~__GFP_WAIT; 94 95 if (sectors >= bio_sectors(bio)) 96 return bio; 97 98 if (bio->bi_rw & REQ_DISCARD) { 99 ret = bio_alloc_bioset(gfp, 1, bs); 100 idx = 0; 101 goto out; 102 } 103 104 bio_for_each_segment(bv, bio, idx) { 105 vcnt = idx - bio->bi_idx; 106 107 if (!nbytes) { 108 ret = bio_alloc_bioset(gfp, vcnt, bs); 109 if (!ret) 110 return NULL; 111 112 memcpy(ret->bi_io_vec, bio_iovec(bio), 113 sizeof(struct bio_vec) * vcnt); 114 115 break; 116 } else if (nbytes < bv->bv_len) { 117 ret = bio_alloc_bioset(gfp, ++vcnt, bs); 118 if (!ret) 119 return NULL; 120 121 memcpy(ret->bi_io_vec, bio_iovec(bio), 122 sizeof(struct bio_vec) * vcnt); 123 124 ret->bi_io_vec[vcnt - 1].bv_len = nbytes; 125 bv->bv_offset += nbytes; 126 bv->bv_len -= nbytes; 127 break; 128 } 129 130 nbytes -= bv->bv_len; 131 } 132 out: 133 ret->bi_bdev = bio->bi_bdev; 134 ret->bi_sector = bio->bi_sector; 135 ret->bi_size = sectors << 9; 136 ret->bi_rw = bio->bi_rw; 137 ret->bi_vcnt = vcnt; 138 ret->bi_max_vecs = vcnt; 139 140 bio->bi_sector += sectors; 141 bio->bi_size -= sectors << 9; 142 bio->bi_idx = idx; 143 144 if (bio_integrity(bio)) { 145 if (bio_integrity_clone(ret, bio, gfp)) { 146 bio_put(ret); 147 return NULL; 148 } 149 150 bio_integrity_trim(ret, 0, bio_sectors(ret)); 151 bio_integrity_trim(bio, bio_sectors(ret), bio_sectors(bio)); 152 } 153 154 return ret; 155 } 156 157 static unsigned bch_bio_max_sectors(struct bio *bio) 158 { 159 unsigned ret = bio_sectors(bio); 160 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 161 unsigned max_segments = min_t(unsigned, BIO_MAX_PAGES, 162 queue_max_segments(q)); 163 struct bio_vec *bv, *end = bio_iovec(bio) + 164 min_t(int, bio_segments(bio), max_segments); 165 166 if (bio->bi_rw & REQ_DISCARD) 167 return min(ret, q->limits.max_discard_sectors); 168 169 if (bio_segments(bio) > max_segments || 170 q->merge_bvec_fn) { 171 ret = 0; 172 173 for (bv = bio_iovec(bio); bv < end; bv++) { 174 struct bvec_merge_data bvm = { 175 .bi_bdev = bio->bi_bdev, 176 .bi_sector = bio->bi_sector, 177 .bi_size = ret << 9, 178 .bi_rw = bio->bi_rw, 179 }; 180 181 if (q->merge_bvec_fn && 182 q->merge_bvec_fn(q, &bvm, bv) < (int) bv->bv_len) 183 break; 184 185 ret += bv->bv_len >> 9; 186 } 187 } 188 189 ret = min(ret, queue_max_sectors(q)); 190 191 WARN_ON(!ret); 192 ret = max_t(int, ret, bio_iovec(bio)->bv_len >> 9); 193 194 return ret; 195 } 196 197 static void bch_bio_submit_split_done(struct closure *cl) 198 { 199 struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl); 200 201 s->bio->bi_end_io = s->bi_end_io; 202 s->bio->bi_private = s->bi_private; 203 bio_endio(s->bio, 0); 204 205 closure_debug_destroy(&s->cl); 206 mempool_free(s, s->p->bio_split_hook); 207 } 208 209 static void bch_bio_submit_split_endio(struct bio *bio, int error) 210 { 211 struct closure *cl = bio->bi_private; 212 struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl); 213 214 if (error) 215 clear_bit(BIO_UPTODATE, &s->bio->bi_flags); 216 217 bio_put(bio); 218 closure_put(cl); 219 } 220 221 static void __bch_bio_submit_split(struct closure *cl) 222 { 223 struct bio_split_hook *s = container_of(cl, struct bio_split_hook, cl); 224 struct bio *bio = s->bio, *n; 225 226 do { 227 n = bch_bio_split(bio, bch_bio_max_sectors(bio), 228 GFP_NOIO, s->p->bio_split); 229 if (!n) 230 continue_at(cl, __bch_bio_submit_split, system_wq); 231 232 n->bi_end_io = bch_bio_submit_split_endio; 233 n->bi_private = cl; 234 235 closure_get(cl); 236 bch_generic_make_request_hack(n); 237 } while (n != bio); 238 239 continue_at(cl, bch_bio_submit_split_done, NULL); 240 } 241 242 void bch_generic_make_request(struct bio *bio, struct bio_split_pool *p) 243 { 244 struct bio_split_hook *s; 245 246 if (!bio_has_data(bio) && !(bio->bi_rw & REQ_DISCARD)) 247 goto submit; 248 249 if (bio_sectors(bio) <= bch_bio_max_sectors(bio)) 250 goto submit; 251 252 s = mempool_alloc(p->bio_split_hook, GFP_NOIO); 253 254 s->bio = bio; 255 s->p = p; 256 s->bi_end_io = bio->bi_end_io; 257 s->bi_private = bio->bi_private; 258 bio_get(bio); 259 260 closure_call(&s->cl, __bch_bio_submit_split, NULL, NULL); 261 return; 262 submit: 263 bch_generic_make_request_hack(bio); 264 } 265 266 /* Bios with headers */ 267 268 void bch_bbio_free(struct bio *bio, struct cache_set *c) 269 { 270 struct bbio *b = container_of(bio, struct bbio, bio); 271 mempool_free(b, c->bio_meta); 272 } 273 274 struct bio *bch_bbio_alloc(struct cache_set *c) 275 { 276 struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO); 277 struct bio *bio = &b->bio; 278 279 bio_init(bio); 280 bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET; 281 bio->bi_max_vecs = bucket_pages(c); 282 bio->bi_io_vec = bio->bi_inline_vecs; 283 284 return bio; 285 } 286 287 void __bch_submit_bbio(struct bio *bio, struct cache_set *c) 288 { 289 struct bbio *b = container_of(bio, struct bbio, bio); 290 291 bio->bi_sector = PTR_OFFSET(&b->key, 0); 292 bio->bi_bdev = PTR_CACHE(c, &b->key, 0)->bdev; 293 294 b->submit_time_us = local_clock_us(); 295 closure_bio_submit(bio, bio->bi_private, PTR_CACHE(c, &b->key, 0)); 296 } 297 298 void bch_submit_bbio(struct bio *bio, struct cache_set *c, 299 struct bkey *k, unsigned ptr) 300 { 301 struct bbio *b = container_of(bio, struct bbio, bio); 302 bch_bkey_copy_single_ptr(&b->key, k, ptr); 303 __bch_submit_bbio(bio, c); 304 } 305 306 /* IO errors */ 307 308 void bch_count_io_errors(struct cache *ca, int error, const char *m) 309 { 310 /* 311 * The halflife of an error is: 312 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh 313 */ 314 315 if (ca->set->error_decay) { 316 unsigned count = atomic_inc_return(&ca->io_count); 317 318 while (count > ca->set->error_decay) { 319 unsigned errors; 320 unsigned old = count; 321 unsigned new = count - ca->set->error_decay; 322 323 /* 324 * First we subtract refresh from count; each time we 325 * succesfully do so, we rescale the errors once: 326 */ 327 328 count = atomic_cmpxchg(&ca->io_count, old, new); 329 330 if (count == old) { 331 count = new; 332 333 errors = atomic_read(&ca->io_errors); 334 do { 335 old = errors; 336 new = ((uint64_t) errors * 127) / 128; 337 errors = atomic_cmpxchg(&ca->io_errors, 338 old, new); 339 } while (old != errors); 340 } 341 } 342 } 343 344 if (error) { 345 char buf[BDEVNAME_SIZE]; 346 unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT, 347 &ca->io_errors); 348 errors >>= IO_ERROR_SHIFT; 349 350 if (errors < ca->set->error_limit) 351 pr_err("%s: IO error on %s, recovering", 352 bdevname(ca->bdev, buf), m); 353 else 354 bch_cache_set_error(ca->set, 355 "%s: too many IO errors %s", 356 bdevname(ca->bdev, buf), m); 357 } 358 } 359 360 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, 361 int error, const char *m) 362 { 363 struct bbio *b = container_of(bio, struct bbio, bio); 364 struct cache *ca = PTR_CACHE(c, &b->key, 0); 365 366 unsigned threshold = bio->bi_rw & REQ_WRITE 367 ? c->congested_write_threshold_us 368 : c->congested_read_threshold_us; 369 370 if (threshold) { 371 unsigned t = local_clock_us(); 372 373 int us = t - b->submit_time_us; 374 int congested = atomic_read(&c->congested); 375 376 if (us > (int) threshold) { 377 int ms = us / 1024; 378 c->congested_last_us = t; 379 380 ms = min(ms, CONGESTED_MAX + congested); 381 atomic_sub(ms, &c->congested); 382 } else if (congested < 0) 383 atomic_inc(&c->congested); 384 } 385 386 bch_count_io_errors(ca, error, m); 387 } 388 389 void bch_bbio_endio(struct cache_set *c, struct bio *bio, 390 int error, const char *m) 391 { 392 struct closure *cl = bio->bi_private; 393 394 bch_bbio_count_io_errors(c, bio, error, m); 395 bio_put(bio); 396 closure_put(cl); 397 } 398