1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
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 | |
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 | |
29 | struct background_work; |
30 | struct background_tracker; |
31 | |
32 | /* |
33 | * Create a new tracker, it will not be able to queue more than |
34 | * 'max_work' entries. |
35 | */ |
36 | struct background_tracker *btracker_create(unsigned int max_work); |
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 | */ |
43 | void btracker_destroy(struct background_tracker *b); |
44 | |
45 | unsigned int btracker_nr_writebacks_queued(struct background_tracker *b); |
46 | unsigned int btracker_nr_demotions_queued(struct background_tracker *b); |
47 | |
48 | /* |
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 | * |
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 | /* |
62 | * Hands out the next piece of work to be performed. |
63 | * Returns -ENODATA if there's no work. |
64 | */ |
65 | int btracker_issue(struct background_tracker *b, struct policy_work **work); |
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 | */ |
76 | bool btracker_promotion_already_present(struct background_tracker *b, |
77 | dm_oblock_t oblock); |
78 | |
79 | /*----------------------------------------------------------------*/ |
80 | |
81 | #endif |
82 | |