summaryrefslogtreecommitdiffstats
path: root/drivers/md/bcache/io.c
blob: 4d93f07f63e515c23e0792331d87f3c2cea1c485 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
// SPDX-License-Identifier: GPL-2.0
/*
 * Some low level IO code, and hacks for various block layer limitations
 *
 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
 * Copyright 2012 Google, Inc.
 */

#include "bcache.h"
#include "bset.h"
#include "debug.h"

#include <linux/blkdev.h>

/* Bios with headers */

void bch_bbio_free(struct bio *bio, struct cache_set *c)
{
	struct bbio *b = container_of(bio, struct bbio, bio);

	mempool_free(b, &c->bio_meta);
}

struct bio *bch_bbio_alloc(struct cache_set *c)
{
	struct bbio *b = mempool_alloc(&c->bio_meta, GFP_NOIO);
	struct bio *bio = &b->bio;

	bio_init(bio, bio->bi_inline_vecs, bucket_pages(c));

	return bio;
}

void __bch_submit_bbio(struct bio *bio, struct cache_set *c)
{
	struct bbio *b = container_of(bio, struct bbio, bio);

	bio->bi_iter.bi_sector	= PTR_OFFSET(&b->key, 0);
	bio_set_dev(bio, PTR_CACHE(c, &b->key, 0)->bdev);

	b->submit_time_us = local_clock_us();
	closure_bio_submit(c, bio, bio->bi_private);
}

void bch_submit_bbio(struct bio *bio, struct cache_set *c,
		     struct bkey *k, unsigned int ptr)
{
	struct bbio *b = container_of(bio, struct bbio, bio);

	bch_bkey_copy_single_ptr(&b->key, k, ptr);
	__bch_submit_bbio(bio, c);
}

/* IO errors */
void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
{
	unsigned int errors;

	WARN_ONCE(!dc, "NULL pointer of struct cached_dev");

	/*
	 * Read-ahead requests on a degrading and recovering md raid
	 * (e.g. raid6) device might be failured immediately by md
	 * raid code, which is not a real hardware media failure. So
	 * we shouldn't count failed REQ_RAHEAD bio to dc->io_errors.
	 */
	if (bio->bi_opf & REQ_RAHEAD) {
		pr_warn_ratelimited("%s: Read-ahead I/O failed on backing device, ignore",
				    dc->backing_dev_name);
		return;
	}

	errors = atomic_add_return(1, &dc->io_errors);
	if (errors < dc->error_limit)
		pr_err("%s: IO error on backing device, unrecoverable",
			dc->backing_dev_name);
	else
		bch_cached_dev_error(dc);
}

void bch_count_io_errors(struct cache *ca,
			 blk_status_t error,
			 int is_read,
			 const char *m)
{
	/*
	 * The halflife of an error is:
	 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
	 */

	if (ca->set->error_decay) {
		unsigned int count = atomic_inc_return(&ca->io_count);

		while (count > ca->set->error_decay) {
			unsigned int errors;
			unsigned int old = count;
			unsigned int new = count - ca->set->error_decay;

			/*
			 * First we subtract refresh from count; each time we
			 * successfully do so, we rescale the errors once:
			 */

			count = atomic_cmpxchg(&ca->io_count, old, new);

			if (count == old) {
				count = new;

				errors = atomic_read(&ca->io_errors);
				do {
					old = errors;
					new = ((uint64_t) errors * 127) / 128;
					errors = atomic_cmpxchg(&ca->io_errors,
								old, new);
				} while (old != errors);
			}
		}
	}

	if (error) {
		unsigned int errors = atomic_add_return(1 << IO_ERROR_SHIFT,
						    &ca->io_errors);
		errors >>= IO_ERROR_SHIFT;

		if (errors < ca->set->error_limit)
			pr_err("%s: IO error on %s%s",
			       ca->cache_dev_name, m,
			       is_read ? ", recovering." : ".");
		else
			bch_cache_set_error(ca->set,
					    "%s: too many IO errors %s",
					    ca->cache_dev_name, m);
	}
}

void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
			      blk_status_t error, const char *m)
{
	struct bbio *b = container_of(bio, struct bbio, bio);
	struct cache *ca = PTR_CACHE(c, &b->key, 0);
	int is_read = (bio_data_dir(bio) == READ ? 1 : 0);

	unsigned int threshold = op_is_write(bio_op(bio))
		? c->congested_write_threshold_us
		: c->congested_read_threshold_us;

	if (threshold) {
		unsigned int t = local_clock_us();
		int us = t - b->submit_time_us;
		int congested = atomic_read(&c->congested);

		if (us > (int) threshold) {
			int ms = us / 1024;

			c->congested_last_us = t;

			ms = min(ms, CONGESTED_MAX + congested);
			atomic_sub(ms, &c->congested);
		} else if (congested < 0)
			atomic_inc(&c->congested);
	}

	bch_count_io_errors(ca, error, is_read, m);
}

void bch_bbio_endio(struct cache_set *c, struct bio *bio,
		    blk_status_t error, const char *m)
{
	struct closure *cl = bio->bi_private;

	bch_bbio_count_io_errors(c, bio, error, m);
	bio_put(bio);
	closure_put(cl);
}