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3bd94003 | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
b29d4986 JT |
2 | /* |
3 | * Copyright (C) 2017 Red Hat. All rights reserved. | |
4 | * | |
5 | * This file is released under the GPL. | |
6 | */ | |
7 | ||
8 | #ifndef DM_CACHE_BACKGROUND_WORK_H | |
9 | #define DM_CACHE_BACKGROUND_WORK_H | |
10 | ||
11 | #include <linux/vmalloc.h> | |
12 | #include "dm-cache-policy.h" | |
13 | ||
14 | /*----------------------------------------------------------------*/ | |
15 | ||
22c40e13 JT |
16 | /* |
17 | * The cache policy decides what background work should be performed, | |
18 | * such as promotions, demotions and writebacks. The core cache target | |
19 | * is in charge of performing the work, and does so when it sees fit. | |
20 | * | |
21 | * The background_tracker acts as a go between. Keeping track of future | |
22 | * work that the policy has decided upon, and handing (issuing) it to | |
23 | * the core target when requested. | |
24 | * | |
25 | * There is no locking in this, so calls will probably need to be | |
26 | * protected with a spinlock. | |
27 | */ | |
28 | ||
b29d4986 JT |
29 | struct background_work; |
30 | struct background_tracker; | |
31 | ||
32 | /* | |
22c40e13 JT |
33 | * Create a new tracker, it will not be able to queue more than |
34 | * 'max_work' entries. | |
b29d4986 JT |
35 | */ |
36 | struct background_tracker *btracker_create(unsigned max_work); | |
22c40e13 JT |
37 | |
38 | /* | |
39 | * Destroy the tracker. No issued, but not complete, work should | |
40 | * exist when this is called. It is fine to have queued but unissued | |
41 | * work. | |
42 | */ | |
b29d4986 JT |
43 | void btracker_destroy(struct background_tracker *b); |
44 | ||
45 | unsigned btracker_nr_writebacks_queued(struct background_tracker *b); | |
46 | unsigned btracker_nr_demotions_queued(struct background_tracker *b); | |
47 | ||
48 | /* | |
22c40e13 JT |
49 | * Queue some work within the tracker. 'work' should point to the work |
50 | * to queue, this will be copied (ownership doesn't pass). If pwork | |
51 | * is not NULL then it will be set to point to the tracker's internal | |
52 | * copy of the work. | |
53 | * | |
b29d4986 JT |
54 | * returns -EINVAL iff the work is already queued. -ENOMEM if the work |
55 | * couldn't be queued for another reason. | |
56 | */ | |
57 | int btracker_queue(struct background_tracker *b, | |
58 | struct policy_work *work, | |
59 | struct policy_work **pwork); | |
60 | ||
61 | /* | |
22c40e13 | 62 | * Hands out the next piece of work to be performed. |
b29d4986 JT |
63 | * Returns -ENODATA if there's no work. |
64 | */ | |
65 | int btracker_issue(struct background_tracker *b, struct policy_work **work); | |
22c40e13 JT |
66 | |
67 | /* | |
68 | * Informs the tracker that the work has been completed and it may forget | |
69 | * about it. | |
70 | */ | |
71 | void btracker_complete(struct background_tracker *b, struct policy_work *op); | |
72 | ||
73 | /* | |
74 | * Predicate to see if an origin block is already scheduled for promotion. | |
75 | */ | |
b29d4986 JT |
76 | bool btracker_promotion_already_present(struct background_tracker *b, |
77 | dm_oblock_t oblock); | |
78 | ||
79 | /*----------------------------------------------------------------*/ | |
80 | ||
81 | #endif |