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