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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_H9#define DM_CACHE_BACKGROUND_WORK_H10 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 target19 * 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 future22 * work that the policy has decided upon, and handing (issuing) it to23 * the core target when requested.24 *25 * There is no locking in this, so calls will probably need to be26 * protected with a spinlock.27 */28 29struct bt_work {30 struct list_head list;31 struct rb_node node;32 struct policy_work work;33};34 35extern struct kmem_cache *btracker_work_cache;36 37struct background_work;38struct background_tracker;39 40/*41 * Create a new tracker, it will not be able to queue more than42 * 'max_work' entries.43 */44struct background_tracker *btracker_create(unsigned int max_work);45 46/*47 * Destroy the tracker. No issued, but not complete, work should48 * exist when this is called. It is fine to have queued but unissued49 * work.50 */51void btracker_destroy(struct background_tracker *b);52 53unsigned int btracker_nr_writebacks_queued(struct background_tracker *b);54unsigned int btracker_nr_demotions_queued(struct background_tracker *b);55 56/*57 * Queue some work within the tracker. 'work' should point to the work58 * to queue, this will be copied (ownership doesn't pass). If pwork59 * is not NULL then it will be set to point to the tracker's internal60 * copy of the work.61 *62 * returns -EINVAL iff the work is already queued. -ENOMEM if the work63 * couldn't be queued for another reason.64 */65int btracker_queue(struct background_tracker *b,66 struct policy_work *work,67 struct policy_work **pwork);68 69/*70 * Hands out the next piece of work to be performed.71 * Returns -ENODATA if there's no work.72 */73int btracker_issue(struct background_tracker *b, struct policy_work **work);74 75/*76 * Informs the tracker that the work has been completed and it may forget77 * about it.78 */79void btracker_complete(struct background_tracker *b, struct policy_work *op);80 81/*82 * Predicate to see if an origin block is already scheduled for promotion.83 */84bool btracker_promotion_already_present(struct background_tracker *b,85 dm_oblock_t oblock);86 87/*----------------------------------------------------------------*/88 89#endif90