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 #include "dm-cache-background-tracker.h" 9 10 /*----------------------------------------------------------------*/ 11 12 #define DM_MSG_PREFIX "dm-background-tracker" 13 14 struct background_tracker { 15 unsigned int max_work; 16 atomic_t pending_promotes; 17 atomic_t pending_writebacks; 18 atomic_t pending_demotes; 19 20 struct list_head issued; 21 struct list_head queued; 22 struct rb_root pending; 23 }; 24 25 struct kmem_cache *btracker_work_cache = NULL; 26 27 struct background_tracker *btracker_create(unsigned int max_work) 28 { 29 struct background_tracker *b = kmalloc(sizeof(*b), GFP_KERNEL); 30 31 if (!b) { 32 DMERR("couldn't create background_tracker"); 33 return NULL; 34 } 35 36 b->max_work = max_work; 37 atomic_set(&b->pending_promotes, 0); 38 atomic_set(&b->pending_writebacks, 0); 39 atomic_set(&b->pending_demotes, 0); 40 41 INIT_LIST_HEAD(&b->issued); 42 INIT_LIST_HEAD(&b->queued); 43 44 b->pending = RB_ROOT; 45 46 return b; 47 } 48 EXPORT_SYMBOL_GPL(btracker_create); 49 50 void btracker_destroy(struct background_tracker *b) 51 { 52 struct bt_work *w, *tmp; 53 54 BUG_ON(!list_empty(&b->issued)); 55 list_for_each_entry_safe (w, tmp, &b->queued, list) { 56 list_del(&w->list); 57 kmem_cache_free(btracker_work_cache, w); 58 } 59 60 kfree(b); 61 } 62 EXPORT_SYMBOL_GPL(btracker_destroy); 63 64 static int cmp_oblock(dm_oblock_t lhs, dm_oblock_t rhs) 65 { 66 if (from_oblock(lhs) < from_oblock(rhs)) 67 return -1; 68 69 if (from_oblock(rhs) < from_oblock(lhs)) 70 return 1; 71 72 return 0; 73 } 74 75 static bool __insert_pending(struct background_tracker *b, 76 struct bt_work *nw) 77 { 78 int cmp; 79 struct bt_work *w; 80 struct rb_node **new = &b->pending.rb_node, *parent = NULL; 81 82 while (*new) { 83 w = container_of(*new, struct bt_work, node); 84 85 parent = *new; 86 cmp = cmp_oblock(w->work.oblock, nw->work.oblock); 87 if (cmp < 0) 88 new = &((*new)->rb_left); 89 90 else if (cmp > 0) 91 new = &((*new)->rb_right); 92 93 else 94 /* already present */ 95 return false; 96 } 97 98 rb_link_node(&nw->node, parent, new); 99 rb_insert_color(&nw->node, &b->pending); 100 101 return true; 102 } 103 104 static struct bt_work *__find_pending(struct background_tracker *b, 105 dm_oblock_t oblock) 106 { 107 int cmp; 108 struct bt_work *w; 109 struct rb_node **new = &b->pending.rb_node; 110 111 while (*new) { 112 w = container_of(*new, struct bt_work, node); 113 114 cmp = cmp_oblock(w->work.oblock, oblock); 115 if (cmp < 0) 116 new = &((*new)->rb_left); 117 118 else if (cmp > 0) 119 new = &((*new)->rb_right); 120 121 else 122 break; 123 } 124 125 return *new ? w : NULL; 126 } 127 128 129 static void update_stats(struct background_tracker *b, struct policy_work *w, int delta) 130 { 131 switch (w->op) { 132 case POLICY_PROMOTE: 133 atomic_add(delta, &b->pending_promotes); 134 break; 135 136 case POLICY_DEMOTE: 137 atomic_add(delta, &b->pending_demotes); 138 break; 139 140 case POLICY_WRITEBACK: 141 atomic_add(delta, &b->pending_writebacks); 142 break; 143 } 144 } 145 146 unsigned int btracker_nr_demotions_queued(struct background_tracker *b) 147 { 148 return atomic_read(&b->pending_demotes); 149 } 150 EXPORT_SYMBOL_GPL(btracker_nr_demotions_queued); 151 152 static bool max_work_reached(struct background_tracker *b) 153 { 154 return atomic_read(&b->pending_promotes) + 155 atomic_read(&b->pending_writebacks) + 156 atomic_read(&b->pending_demotes) >= b->max_work; 157 } 158 159 static struct bt_work *alloc_work(struct background_tracker *b) 160 { 161 if (max_work_reached(b)) 162 return NULL; 163 164 return kmem_cache_alloc(btracker_work_cache, GFP_NOWAIT); 165 } 166 167 int btracker_queue(struct background_tracker *b, 168 struct policy_work *work, 169 struct policy_work **pwork) 170 { 171 struct bt_work *w; 172 173 if (pwork) 174 *pwork = NULL; 175 176 w = alloc_work(b); 177 if (!w) 178 return -ENOMEM; 179 180 memcpy(&w->work, work, sizeof(*work)); 181 182 if (!__insert_pending(b, w)) { 183 /* 184 * There was a race, we'll just ignore this second 185 * bit of work for the same oblock. 186 */ 187 kmem_cache_free(btracker_work_cache, w); 188 return -EINVAL; 189 } 190 191 if (pwork) { 192 *pwork = &w->work; 193 list_add(&w->list, &b->issued); 194 } else 195 list_add(&w->list, &b->queued); 196 update_stats(b, &w->work, 1); 197 198 return 0; 199 } 200 EXPORT_SYMBOL_GPL(btracker_queue); 201 202 /* 203 * Returns -ENODATA if there's no work. 204 */ 205 int btracker_issue(struct background_tracker *b, struct policy_work **work) 206 { 207 struct bt_work *w; 208 209 if (list_empty(&b->queued)) 210 return -ENODATA; 211 212 w = list_first_entry(&b->queued, struct bt_work, list); 213 list_move(&w->list, &b->issued); 214 *work = &w->work; 215 216 return 0; 217 } 218 EXPORT_SYMBOL_GPL(btracker_issue); 219 220 void btracker_complete(struct background_tracker *b, 221 struct policy_work *op) 222 { 223 struct bt_work *w = container_of(op, struct bt_work, work); 224 225 update_stats(b, &w->work, -1); 226 rb_erase(&w->node, &b->pending); 227 list_del(&w->list); 228 kmem_cache_free(btracker_work_cache, w); 229 } 230 EXPORT_SYMBOL_GPL(btracker_complete); 231 232 bool btracker_promotion_already_present(struct background_tracker *b, 233 dm_oblock_t oblock) 234 { 235 return __find_pending(b, oblock) != NULL; 236 } 237 EXPORT_SYMBOL_GPL(btracker_promotion_already_present); 238 239 /*----------------------------------------------------------------*/ 240