Linux kernel mirror (for testing)
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _BCACHE_WRITEBACK_H
3#define _BCACHE_WRITEBACK_H
4
5#define CUTOFF_WRITEBACK 40
6#define CUTOFF_WRITEBACK_SYNC 70
7
8#define MAX_WRITEBACKS_IN_PASS 5
9#define MAX_WRITESIZE_IN_PASS 5000 /* *512b */
10
11#define WRITEBACK_RATE_UPDATE_SECS_MAX 60
12#define WRITEBACK_RATE_UPDATE_SECS_DEFAULT 5
13
14/*
15 * 14 (16384ths) is chosen here as something that each backing device
16 * should be a reasonable fraction of the share, and not to blow up
17 * until individual backing devices are a petabyte.
18 */
19#define WRITEBACK_SHARE_SHIFT 14
20
21static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
22{
23 uint64_t i, ret = 0;
24
25 for (i = 0; i < d->nr_stripes; i++)
26 ret += atomic_read(d->stripe_sectors_dirty + i);
27
28 return ret;
29}
30
31static inline unsigned int offset_to_stripe(struct bcache_device *d,
32 uint64_t offset)
33{
34 do_div(offset, d->stripe_size);
35 return offset;
36}
37
38static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
39 uint64_t offset,
40 unsigned int nr_sectors)
41{
42 unsigned int stripe = offset_to_stripe(&dc->disk, offset);
43
44 while (1) {
45 if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
46 return true;
47
48 if (nr_sectors <= dc->disk.stripe_size)
49 return false;
50
51 nr_sectors -= dc->disk.stripe_size;
52 stripe++;
53 }
54}
55
56static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
57 unsigned int cache_mode, bool would_skip)
58{
59 unsigned int in_use = dc->disk.c->gc_stats.in_use;
60
61 if (cache_mode != CACHE_MODE_WRITEBACK ||
62 test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
63 in_use > CUTOFF_WRITEBACK_SYNC)
64 return false;
65
66 if (dc->partial_stripes_expensive &&
67 bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
68 bio_sectors(bio)))
69 return true;
70
71 if (would_skip)
72 return false;
73
74 return (op_is_sync(bio->bi_opf) ||
75 bio->bi_opf & (REQ_META|REQ_PRIO) ||
76 in_use <= CUTOFF_WRITEBACK);
77}
78
79static inline void bch_writeback_queue(struct cached_dev *dc)
80{
81 if (!IS_ERR_OR_NULL(dc->writeback_thread))
82 wake_up_process(dc->writeback_thread);
83}
84
85static inline void bch_writeback_add(struct cached_dev *dc)
86{
87 if (!atomic_read(&dc->has_dirty) &&
88 !atomic_xchg(&dc->has_dirty, 1)) {
89 if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
90 SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
91 /* XXX: should do this synchronously */
92 bch_write_bdev_super(dc, NULL);
93 }
94
95 bch_writeback_queue(dc);
96 }
97}
98
99void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
100 uint64_t offset, int nr_sectors);
101
102void bch_sectors_dirty_init(struct bcache_device *d);
103void bch_cached_dev_writeback_init(struct cached_dev *dc);
104int bch_cached_dev_writeback_start(struct cached_dev *dc);
105
106#endif