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
 17void bch_bbio_free(struct bio *bio, struct cache_set *c)
 18{
 19	struct bbio *b = container_of(bio, struct bbio, bio);
 20	mempool_free(b, c->bio_meta);
 21}
 22
 23struct bio *bch_bbio_alloc(struct cache_set *c)
 24{
 25	struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO);
 26	struct bio *bio = &b->bio;
 27
 28	bio_init(bio, bio->bi_inline_vecs, bucket_pages(c));
 29
 30	return bio;
 31}
 32
 33void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
 34{
 35	struct bbio *b = container_of(bio, struct bbio, bio);
 36
 37	bio->bi_iter.bi_sector	= PTR_OFFSET(&b->key, 0);
 38	bio_set_dev(bio, PTR_CACHE(c, &b->key, 0)->bdev);
 39
 40	b->submit_time_us = local_clock_us();
 41	closure_bio_submit(c, bio, bio->bi_private);
 42}
 43
 44void bch_submit_bbio(struct bio *bio, struct cache_set *c,
 45		     struct bkey *k, unsigned ptr)
 46{
 47	struct bbio *b = container_of(bio, struct bbio, bio);
 48	bch_bkey_copy_single_ptr(&b->key, k, ptr);
 49	__bch_submit_bbio(bio, c);
 50}
 51
 52/* IO errors */
 53void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
 54{
 55	unsigned errors;
 56
 57	WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
 58
 59	errors = atomic_add_return(1, &dc->io_errors);
 60	if (errors < dc->error_limit)
 61		pr_err("%s: IO error on backing device, unrecoverable",
 62			dc->backing_dev_name);
 63	else
 64		bch_cached_dev_error(dc);
 65}
 66
 67void bch_count_io_errors(struct cache *ca,
 68			 blk_status_t error,
 69			 int is_read,
 70			 const char *m)
 71{
 72	/*
 73	 * The halflife of an error is:
 74	 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
 75	 */
 76
 77	if (ca->set->error_decay) {
 78		unsigned count = atomic_inc_return(&ca->io_count);
 79
 80		while (count > ca->set->error_decay) {
 81			unsigned errors;
 82			unsigned old = count;
 83			unsigned new = count - ca->set->error_decay;
 84
 85			/*
 86			 * First we subtract refresh from count; each time we
 87			 * succesfully do so, we rescale the errors once:
 88			 */
 89
 90			count = atomic_cmpxchg(&ca->io_count, old, new);
 91
 92			if (count == old) {
 93				count = new;
 94
 95				errors = atomic_read(&ca->io_errors);
 96				do {
 97					old = errors;
 98					new = ((uint64_t) errors * 127) / 128;
 99					errors = atomic_cmpxchg(&ca->io_errors,
100								old, new);
101				} while (old != errors);
102			}
103		}
104	}
105
106	if (error) {
107		unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT,
108						    &ca->io_errors);
109		errors >>= IO_ERROR_SHIFT;
110
111		if (errors < ca->set->error_limit)
112			pr_err("%s: IO error on %s%s",
113			       ca->cache_dev_name, m,
114			       is_read ? ", recovering." : ".");
115		else
116			bch_cache_set_error(ca->set,
117					    "%s: too many IO errors %s",
118					    ca->cache_dev_name, m);
119	}
120}
121
122void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
123			      blk_status_t error, const char *m)
124{
125	struct bbio *b = container_of(bio, struct bbio, bio);
126	struct cache *ca = PTR_CACHE(c, &b->key, 0);
127	int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
128
129	unsigned threshold = op_is_write(bio_op(bio))
130		? c->congested_write_threshold_us
131		: c->congested_read_threshold_us;
132
133	if (threshold) {
134		unsigned t = local_clock_us();
135
136		int us = t - b->submit_time_us;
137		int congested = atomic_read(&c->congested);
138
139		if (us > (int) threshold) {
140			int ms = us / 1024;
141			c->congested_last_us = t;
142
143			ms = min(ms, CONGESTED_MAX + congested);
144			atomic_sub(ms, &c->congested);
145		} else if (congested < 0)
146			atomic_inc(&c->congested);
147	}
148
149	bch_count_io_errors(ca, error, is_read, m);
150}
151
152void bch_bbio_endio(struct cache_set *c, struct bio *bio,
153		    blk_status_t error, const char *m)
154{
155	struct closure *cl = bio->bi_private;
156
157	bch_bbio_count_io_errors(c, bio, error, m);
158	bio_put(bio);
159	closure_put(cl);
160}