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 bt_work { 30 struct list_head list; 31 struct rb_node node; 32 struct policy_work work; 33 }; 34 35 extern struct kmem_cache *btracker_work_cache; 36 37 struct background_work; 38 struct background_tracker; 39 40 /* 41 * Create a new tracker, it will not be able to queue more than 42 * 'max_work' entries. 43 */ 44 struct background_tracker *btracker_create(unsigned int max_work); 45 46 /* 47 * Destroy the tracker. No issued, but not complete, work should 48 * exist when this is called. It is fine to have queued but unissued 49 * work. 50 */ 51 void btracker_destroy(struct background_tracker *b); 52 53 unsigned int btracker_nr_demotions_queued(struct background_tracker *b); 54 55 /* 56 * Queue some work within the tracker. 'work' should point to the work 57 * to queue, this will be copied (ownership doesn't pass). If pwork 58 * is not NULL then it will be set to point to the tracker's internal 59 * copy of the work. 60 * 61 * returns -EINVAL iff the work is already queued. -ENOMEM if the work 62 * couldn't be queued for another reason. 63 */ 64 int btracker_queue(struct background_tracker *b, 65 struct policy_work *work, 66 struct policy_work **pwork); 67 68 /* 69 * Hands out the next piece of work to be performed. 70 * Returns -ENODATA if there's no work. 71 */ 72 int btracker_issue(struct background_tracker *b, struct policy_work **work); 73 74 /* 75 * Informs the tracker that the work has been completed and it may forget 76 * about it. 77 */ 78 void btracker_complete(struct background_tracker *b, struct policy_work *op); 79 80 /* 81 * Predicate to see if an origin block is already scheduled for promotion. 82 */ 83 bool btracker_promotion_already_present(struct background_tracker *b, 84 dm_oblock_t oblock); 85 86 /*----------------------------------------------------------------*/ 87 88 #endif 89