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 
bch_bbio_free(struct bio * bio,struct cache_set * c)17 void bch_bbio_free(struct bio *bio, struct cache_set *c)
18 {
19 	struct bbio *b = container_of(bio, struct bbio, bio);
20 
21 	mempool_free(b, &c->bio_meta);
22 }
23 
bch_bbio_alloc(struct cache_set * c)24 struct bio *bch_bbio_alloc(struct cache_set *c)
25 {
26 	struct bbio *b = mempool_alloc(&c->bio_meta, GFP_NOIO);
27 	struct bio *bio = &b->bio;
28 
29 	bio_init(bio, NULL, bio->bi_inline_vecs,
30 		 meta_bucket_pages(&c->cache->sb), 0);
31 
32 	return bio;
33 }
34 
__bch_submit_bbio(struct bio * bio,struct cache_set * c)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_set_dev(bio, c->cache->bdev);
41 
42 	b->submit_time_us = local_clock_us();
43 	closure_bio_submit(c, bio, bio->bi_private);
44 }
45 
bch_submit_bbio(struct bio * bio,struct cache_set * c,struct bkey * k,unsigned int ptr)46 void bch_submit_bbio(struct bio *bio, struct cache_set *c,
47 		     struct bkey *k, unsigned int ptr)
48 {
49 	struct bbio *b = container_of(bio, struct bbio, bio);
50 
51 	bch_bkey_copy_single_ptr(&b->key, k, ptr);
52 	__bch_submit_bbio(bio, c);
53 }
54 
55 /* IO errors */
bch_count_backing_io_errors(struct cached_dev * dc,struct bio * bio)56 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio)
57 {
58 	unsigned int errors;
59 
60 	WARN_ONCE(!dc, "NULL pointer of struct cached_dev");
61 
62 	/*
63 	 * Read-ahead requests on a degrading and recovering md raid
64 	 * (e.g. raid6) device might be failured immediately by md
65 	 * raid code, which is not a real hardware media failure. So
66 	 * we shouldn't count failed REQ_RAHEAD bio to dc->io_errors.
67 	 */
68 	if (bio->bi_opf & REQ_RAHEAD) {
69 		pr_warn_ratelimited("%pg: Read-ahead I/O failed on backing device, ignore\n",
70 				    dc->bdev);
71 		return;
72 	}
73 
74 	errors = atomic_add_return(1, &dc->io_errors);
75 	if (errors < dc->error_limit)
76 		pr_err("%pg: IO error on backing device, unrecoverable\n",
77 			dc->bdev);
78 	else
79 		bch_cached_dev_error(dc);
80 }
81 
bch_count_io_errors(struct cache * ca,blk_status_t error,int is_read,const char * m)82 void bch_count_io_errors(struct cache *ca,
83 			 blk_status_t error,
84 			 int is_read,
85 			 const char *m)
86 {
87 	/*
88 	 * The halflife of an error is:
89 	 * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh
90 	 */
91 
92 	if (ca->set->error_decay) {
93 		unsigned int count = atomic_inc_return(&ca->io_count);
94 
95 		while (count > ca->set->error_decay) {
96 			unsigned int errors;
97 			unsigned int old = count;
98 			unsigned int new = count - ca->set->error_decay;
99 
100 			/*
101 			 * First we subtract refresh from count; each time we
102 			 * successfully do so, we rescale the errors once:
103 			 */
104 
105 			count = atomic_cmpxchg(&ca->io_count, old, new);
106 
107 			if (count == old) {
108 				count = new;
109 
110 				errors = atomic_read(&ca->io_errors);
111 				do {
112 					old = errors;
113 					new = ((uint64_t) errors * 127) / 128;
114 					errors = atomic_cmpxchg(&ca->io_errors,
115 								old, new);
116 				} while (old != errors);
117 			}
118 		}
119 	}
120 
121 	if (error) {
122 		unsigned int errors = atomic_add_return(1 << IO_ERROR_SHIFT,
123 						    &ca->io_errors);
124 		errors >>= IO_ERROR_SHIFT;
125 
126 		if (errors < ca->set->error_limit)
127 			pr_err("%pg: IO error on %s%s\n",
128 			       ca->bdev, m,
129 			       is_read ? ", recovering." : ".");
130 		else
131 			bch_cache_set_error(ca->set,
132 					    "%pg: too many IO errors %s\n",
133 					    ca->bdev, m);
134 	}
135 }
136 
bch_bbio_count_io_errors(struct cache_set * c,struct bio * bio,blk_status_t error,const char * m)137 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,
138 			      blk_status_t error, const char *m)
139 {
140 	struct bbio *b = container_of(bio, struct bbio, bio);
141 	struct cache *ca = c->cache;
142 	int is_read = (bio_data_dir(bio) == READ ? 1 : 0);
143 
144 	unsigned int threshold = op_is_write(bio_op(bio))
145 		? c->congested_write_threshold_us
146 		: c->congested_read_threshold_us;
147 
148 	if (threshold) {
149 		unsigned int t = local_clock_us();
150 		int us = t - b->submit_time_us;
151 		int congested = atomic_read(&c->congested);
152 
153 		if (us > (int) threshold) {
154 			int ms = us / 1024;
155 
156 			c->congested_last_us = t;
157 
158 			ms = min(ms, CONGESTED_MAX + congested);
159 			atomic_sub(ms, &c->congested);
160 		} else if (congested < 0)
161 			atomic_inc(&c->congested);
162 	}
163 
164 	bch_count_io_errors(ca, error, is_read, m);
165 }
166 
bch_bbio_endio(struct cache_set * c,struct bio * bio,blk_status_t error,const char * m)167 void bch_bbio_endio(struct cache_set *c, struct bio *bio,
168 		    blk_status_t error, const char *m)
169 {
170 	struct closure *cl = bio->bi_private;
171 
172 	bch_bbio_count_io_errors(c, bio, error, m);
173 	bio_put(bio);
174 	closure_put(cl);
175 }
176