diff options
Diffstat (limited to 'drivers/md/dm-cache-background-tracker.h')
| -rw-r--r-- | drivers/md/dm-cache-background-tracker.h | 47 |
1 files changed, 41 insertions, 6 deletions
diff --git a/drivers/md/dm-cache-background-tracker.h b/drivers/md/dm-cache-background-tracker.h index 27ab90dbc275..5b8f5c667b81 100644 --- a/drivers/md/dm-cache-background-tracker.h +++ b/drivers/md/dm-cache-background-tracker.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ /* * Copyright (C) 2017 Red Hat. All rights reserved. * @@ -12,19 +13,44 @@ /*----------------------------------------------------------------*/ +/* + * 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; /* - * FIXME: discuss lack of locking in all methods. + * 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. */ -struct background_tracker *btracker_create(unsigned max_work); void btracker_destroy(struct background_tracker *b); -unsigned btracker_nr_writebacks_queued(struct background_tracker *b); -unsigned btracker_nr_demotions_queued(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. */ @@ -33,11 +59,20 @@ int btracker_queue(struct background_tracker *b, 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); -void btracker_complete(struct background_tracker *b, - struct policy_work *op); + +/* + * 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); |