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_H 9 #define DM_CACHE_BACKGROUND_WORK_H 10 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 target 19 * 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 future 22 * work that the policy has decided upon, and handing (issuing) it to 23 * the core target when requested. 24 * 25 * There is no locking in this, so calls will probably need to be 26 * protected with a spinlock. 27 */ 28 29 struct background_work; 30 struct background_tracker; 31 32 /* 33 * Create a new tracker, it will not be able to queue more than 34 * 'max_work' entries. 35 */ 36 struct background_tracker *btracker_create(unsigned int max_work); 37 38 /* 39 * Destroy the tracker. No issued, but not complete, work should 40 * exist when this is called. It is fine to have queued but unissued 41 * work. 42 */ 43 void btracker_destroy(struct background_tracker *b); 44 45 unsigned int btracker_nr_writebacks_queued(struct background_tracker *b); 46 unsigned int btracker_nr_demotions_queued(struct background_tracker *b); 47 48 /* 49 * Queue some work within the tracker. 'work' should point to the work 50 * to queue, this will be copied (ownership doesn't pass). If pwork 51 * is not NULL then it will be set to point to the tracker's internal 52 * copy of the work. 53 * 54 * returns -EINVAL iff the work is already queued. -ENOMEM if the work 55 * couldn't be queued for another reason. 56 */ 57 int btracker_queue(struct background_tracker *b, 58 struct policy_work *work, 59 struct policy_work **pwork); 60 61 /* 62 * Hands out the next piece of work to be performed. 63 * Returns -ENODATA if there's no work. 64 */ 65 int btracker_issue(struct background_tracker *b, struct policy_work **work); 66 67 /* 68 * Informs the tracker that the work has been completed and it may forget 69 * about it. 70 */ 71 void btracker_complete(struct background_tracker *b, struct policy_work *op); 72 73 /* 74 * Predicate to see if an origin block is already scheduled for promotion. 75 */ 76 bool btracker_promotion_already_present(struct background_tracker *b, 77 dm_oblock_t oblock); 78 79 /*----------------------------------------------------------------*/ 80 81 #endif 82