81 lines
2.4 KiB
C
81 lines
2.4 KiB
C
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/*
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* Copyright (C) 2017 Red Hat. All rights reserved.
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*
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* This file is released under the GPL.
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*/
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#ifndef DM_CACHE_BACKGROUND_WORK_H
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#define DM_CACHE_BACKGROUND_WORK_H
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#include <linux/vmalloc.h>
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#include "dm-cache-policy.h"
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/*----------------------------------------------------------------*/
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/*
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* The cache policy decides what background work should be performed,
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* such as promotions, demotions and writebacks. The core cache target
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* is in charge of performing the work, and does so when it sees fit.
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*
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* The background_tracker acts as a go between. Keeping track of future
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* work that the policy has decided upon, and handing (issuing) it to
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* the core target when requested.
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*
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* There is no locking in this, so calls will probably need to be
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* protected with a spinlock.
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*/
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struct background_work;
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struct background_tracker;
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/*
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* Create a new tracker, it will not be able to queue more than
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* 'max_work' entries.
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*/
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struct background_tracker *btracker_create(unsigned int max_work);
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/*
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* Destroy the tracker. No issued, but not complete, work should
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* exist when this is called. It is fine to have queued but unissued
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* work.
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*/
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void btracker_destroy(struct background_tracker *b);
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unsigned int btracker_nr_writebacks_queued(struct background_tracker *b);
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unsigned int btracker_nr_demotions_queued(struct background_tracker *b);
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/*
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* Queue some work within the tracker. 'work' should point to the work
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* to queue, this will be copied (ownership doesn't pass). If pwork
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* is not NULL then it will be set to point to the tracker's internal
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* copy of the work.
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*
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* returns -EINVAL iff the work is already queued. -ENOMEM if the work
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* couldn't be queued for another reason.
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*/
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int btracker_queue(struct background_tracker *b,
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struct policy_work *work,
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struct policy_work **pwork);
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/*
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* Hands out the next piece of work to be performed.
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* Returns -ENODATA if there's no work.
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*/
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int btracker_issue(struct background_tracker *b, struct policy_work **work);
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/*
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* Informs the tracker that the work has been completed and it may forget
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* about it.
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*/
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void btracker_complete(struct background_tracker *b, struct policy_work *op);
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/*
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* Predicate to see if an origin block is already scheduled for promotion.
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*/
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bool btracker_promotion_already_present(struct background_tracker *b,
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dm_oblock_t oblock);
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/*----------------------------------------------------------------*/
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#endif
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