// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2017 Red Hat. All rights reserved. * * This file is released under the GPL. */ #include "dm-cache-background-tracker.h" /*----------------------------------------------------------------*/ #define DM_MSG_PREFIX "dm-background-tracker" struct background_tracker {	unsigned int max_work;	atomic_t pending_promotes;	atomic_t pending_writebacks;	atomic_t pending_demotes; 	struct list_head issued;	struct list_head queued;	struct rb_root pending;}; struct kmem_cache *btracker_work_cache = NULL; struct background_tracker *btracker_create(unsigned int max_work){	struct background_tracker *b = kmalloc_obj(*b); 	if (!b) {		DMERR("couldn't create background_tracker");		return NULL;	} 	b->max_work = max_work;	atomic_set(&b->pending_promotes, 0);	atomic_set(&b->pending_writebacks, 0);	atomic_set(&b->pending_demotes, 0); 	INIT_LIST_HEAD(&b->issued);	INIT_LIST_HEAD(&b->queued); 	b->pending = RB_ROOT; 	return b;}EXPORT_SYMBOL_GPL(btracker_create); void btracker_destroy(struct background_tracker *b){	struct bt_work *w, *tmp; 	BUG_ON(!list_empty(&b->issued));	list_for_each_entry_safe (w, tmp, &b->queued, list) {		list_del(&w->list);		kmem_cache_free(btracker_work_cache, w);	} 	kfree(b);}EXPORT_SYMBOL_GPL(btracker_destroy); static int cmp_oblock(dm_oblock_t lhs, dm_oblock_t rhs){	if (from_oblock(lhs) < from_oblock(rhs))		return -1; 	if (from_oblock(rhs) < from_oblock(lhs))		return 1; 	return 0;} static bool __insert_pending(struct background_tracker *b,			     struct bt_work *nw){	int cmp;	struct bt_work *w;	struct rb_node **new = &b->pending.rb_node, *parent = NULL; 	while (*new) {		w = container_of(*new, struct bt_work, node); 		parent = *new;		cmp = cmp_oblock(w->work.oblock, nw->work.oblock);		if (cmp < 0)			new = &((*new)->rb_left); 		else if (cmp > 0)			new = &((*new)->rb_right); 		else			/* already present */			return false;	} 	rb_link_node(&nw->node, parent, new);	rb_insert_color(&nw->node, &b->pending); 	return true;} static struct bt_work *__find_pending(struct background_tracker *b,				      dm_oblock_t oblock){	int cmp;	struct bt_work *w;	struct rb_node **new = &b->pending.rb_node; 	while (*new) {		w = container_of(*new, struct bt_work, node); 		cmp = cmp_oblock(w->work.oblock, oblock);		if (cmp < 0)			new = &((*new)->rb_left); 		else if (cmp > 0)			new = &((*new)->rb_right); 		else			break;	} 	return *new ? w : NULL;}  static void update_stats(struct background_tracker *b, struct policy_work *w, int delta){	switch (w->op) {	case POLICY_PROMOTE:		atomic_add(delta, &b->pending_promotes);		break; 	case POLICY_DEMOTE:		atomic_add(delta, &b->pending_demotes);		break; 	case POLICY_WRITEBACK:		atomic_add(delta, &b->pending_writebacks);		break;	}} unsigned int btracker_nr_demotions_queued(struct background_tracker *b){	return atomic_read(&b->pending_demotes);}EXPORT_SYMBOL_GPL(btracker_nr_demotions_queued); static bool max_work_reached(struct background_tracker *b){	return atomic_read(&b->pending_promotes) +		atomic_read(&b->pending_writebacks) +		atomic_read(&b->pending_demotes) >= b->max_work;} static struct bt_work *alloc_work(struct background_tracker *b){	if (max_work_reached(b))		return NULL; 	return kmem_cache_alloc(btracker_work_cache, GFP_NOWAIT);} int btracker_queue(struct background_tracker *b,		   struct policy_work *work,		   struct policy_work **pwork){	struct bt_work *w; 	if (pwork)		*pwork = NULL; 	w = alloc_work(b);	if (!w)		return -ENOMEM; 	memcpy(&w->work, work, sizeof(*work)); 	if (!__insert_pending(b, w)) {		/*		 * There was a race, we'll just ignore this second		 * bit of work for the same oblock.		 */		kmem_cache_free(btracker_work_cache, w);		return -EINVAL;	} 	if (pwork) {		*pwork = &w->work;		list_add(&w->list, &b->issued);	} else		list_add(&w->list, &b->queued);	update_stats(b, &w->work, 1); 	return 0;}EXPORT_SYMBOL_GPL(btracker_queue); /* * Returns -ENODATA if there's no work. */int btracker_issue(struct background_tracker *b, struct policy_work **work){	struct bt_work *w; 	if (list_empty(&b->queued))		return -ENODATA; 	w = list_first_entry(&b->queued, struct bt_work, list);	list_move(&w->list, &b->issued);	*work = &w->work; 	return 0;}EXPORT_SYMBOL_GPL(btracker_issue); void btracker_complete(struct background_tracker *b,		       struct policy_work *op){	struct bt_work *w = container_of(op, struct bt_work, work); 	update_stats(b, &w->work, -1);	rb_erase(&w->node, &b->pending);	list_del(&w->list);	kmem_cache_free(btracker_work_cache, w);}EXPORT_SYMBOL_GPL(btracker_complete); bool btracker_promotion_already_present(struct background_tracker *b,					dm_oblock_t oblock){	return __find_pending(b, oblock) != NULL;}EXPORT_SYMBOL_GPL(btracker_promotion_already_present); /*----------------------------------------------------------------*/