/* SPDX-License-Identifier: GPL-2.0-only */ /* * 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