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 } 146