| 1 |
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| 2 | |
| 3 | * Copyright (C) 2017 Red Hat. All rights reserved.
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| 4 | *
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| 5 | * This file is released under the GPL.
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| 6 |
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| 7 |
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| 8 | #ifndef DM_CACHE_BACKGROUND_WORK_H
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| 9 | #define DM_CACHE_BACKGROUND_WORK_H
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| 10 |
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| 11 | #include <linux/vmalloc.h>
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| 12 | #include "dm-cache-policy.h"
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| 13 |
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| 14 |
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| 15 |
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| 16 | |
| 17 | * The cache policy decides what background work should be performed,
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| 18 | * such as promotions, demotions and writebacks. The core cache target
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| 19 | * is in charge of performing the work, and does so when it sees fit.
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| 20 | *
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| 21 | * The background_tracker acts as a go between. Keeping track of future
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| 22 | * work that the policy has decided upon, and handing (issuing) it to
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| 23 | * the core target when requested.
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| 24 | *
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| 25 | * There is no locking in this, so calls will probably need to be
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| 26 | * protected with a spinlock.
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| 27 |
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| 28 |
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| 29 | struct bt_work {
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| 30 | struct list_head list;
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| 31 | struct rb_node node;
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| 32 | struct policy_work work;
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| 33 | };
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| 34 |
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| 35 | extern struct kmem_cache *btracker_work_cache;
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| 36 |
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| 37 | struct background_work;
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| 38 | struct background_tracker;
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| 39 |
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| 40 | |
| 41 | * Create a new tracker, it will not be able to queue more than
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| 42 | * 'max_work' entries.
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| 43 |
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| 44 | struct background_tracker *btracker_create(unsigned int max_work);
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| 45 |
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| 46 | |
| 47 | * Destroy the tracker. No issued, but not complete, work should
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| 48 | * exist when this is called. It is fine to have queued but unissued
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| 49 | * work.
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| 50 |
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| 51 | void btracker_destroy(struct background_tracker *b);
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| 52 |
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| 53 | unsigned int btracker_nr_demotions_queued(struct background_tracker *b);
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| 54 |
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| 55 | |
| 56 | * Queue some work within the tracker. 'work' should point to the work
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| 57 | * to queue, this will be copied (ownership doesn't pass). If pwork
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| 58 | * is not NULL then it will be set to point to the tracker's internal
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| 59 | * copy of the work.
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| 60 | *
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| 61 | * returns -EINVAL iff the work is already queued. -ENOMEM if the work
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| 62 | * couldn't be queued for another reason.
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| 63 |
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| 64 | int btracker_queue(struct background_tracker *b,
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| 65 | struct policy_work *work,
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| 66 | struct policy_work **pwork);
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| 67 |
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| 68 | |
| 69 | * Hands out the next piece of work to be performed.
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| 70 | * Returns -ENODATA if there's no work.
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| 71 |
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| 72 | int btracker_issue(struct background_tracker *b, struct policy_work **work);
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| 73 |
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| 74 | |
| 75 | * Informs the tracker that the work has been completed and it may forget
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| 76 | * about it.
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| 77 |
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| 78 | void btracker_complete(struct background_tracker *b, struct policy_work *op);
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| 79 |
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| 80 | |
| 81 | * Predicate to see if an origin block is already scheduled for promotion.
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| 82 |
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| 83 | bool btracker_promotion_already_present(struct background_tracker *b,
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| 84 | dm_oblock_t oblock);
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| 85 |
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| 86 |
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| 87 |
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| 88 | #endif
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