1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_BACKING_DEV_DEFS_H 3 #define __LINUX_BACKING_DEV_DEFS_H 4 5 #include <linux/list.h> 6 #include <linux/radix-tree.h> 7 #include <linux/rbtree.h> 8 #include <linux/spinlock.h> 9 #include <linux/percpu_counter.h> 10 #include <linux/percpu-refcount.h> 11 #include <linux/flex_proportions.h> 12 #include <linux/timer.h> 13 #include <linux/workqueue.h> 14 #include <linux/kref.h> 15 #include <linux/refcount.h> 16 17 struct page; 18 struct device; 19 struct dentry; 20 21 /* 22 * Bits in bdi_writeback.state 23 */ 24 enum wb_state { 25 WB_registered, /* bdi_register() was done */ 26 WB_writeback_running, /* Writeback is in progress */ 27 WB_has_dirty_io, /* Dirty inodes on ->b_{dirty|io|more_io} */ 28 WB_start_all, /* nr_pages == 0 (all) work pending */ 29 }; 30 31 enum wb_congested_state { 32 WB_async_congested, /* The async (write) queue is getting full */ 33 WB_sync_congested, /* The sync queue is getting full */ 34 }; 35 36 typedef int (congested_fn)(void *, int); 37 38 enum wb_stat_item { 39 WB_RECLAIMABLE, 40 WB_WRITEBACK, 41 WB_DIRTIED, 42 WB_WRITTEN, 43 NR_WB_STAT_ITEMS 44 }; 45 46 #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 47 48 /* 49 * why some writeback work was initiated 50 */ 51 enum wb_reason { 52 WB_REASON_BACKGROUND, 53 WB_REASON_VMSCAN, 54 WB_REASON_SYNC, 55 WB_REASON_PERIODIC, 56 WB_REASON_LAPTOP_TIMER, 57 WB_REASON_FS_FREE_SPACE, 58 /* 59 * There is no bdi forker thread any more and works are done 60 * by emergency worker, however, this is TPs userland visible 61 * and we'll be exposing exactly the same information, 62 * so it has a mismatch name. 63 */ 64 WB_REASON_FORKER_THREAD, 65 WB_REASON_FOREIGN_FLUSH, 66 67 WB_REASON_MAX, 68 }; 69 70 struct wb_completion { 71 atomic_t cnt; 72 wait_queue_head_t *waitq; 73 }; 74 75 #define __WB_COMPLETION_INIT(_waitq) \ 76 (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) } 77 78 /* 79 * If one wants to wait for one or more wb_writeback_works, each work's 80 * ->done should be set to a wb_completion defined using the following 81 * macro. Once all work items are issued with wb_queue_work(), the caller 82 * can wait for the completion of all using wb_wait_for_completion(). Work 83 * items which are waited upon aren't freed automatically on completion. 84 */ 85 #define WB_COMPLETION_INIT(bdi) __WB_COMPLETION_INIT(&(bdi)->wb_waitq) 86 87 #define DEFINE_WB_COMPLETION(cmpl, bdi) \ 88 struct wb_completion cmpl = WB_COMPLETION_INIT(bdi) 89 90 /* 91 * For cgroup writeback, multiple wb's may map to the same blkcg. Those 92 * wb's can operate mostly independently but should share the congested 93 * state. To facilitate such sharing, the congested state is tracked using 94 * the following struct which is created on demand, indexed by blkcg ID on 95 * its bdi, and refcounted. 96 */ 97 struct bdi_writeback_congested { 98 unsigned long state; /* WB_[a]sync_congested flags */ 99 refcount_t refcnt; /* nr of attached wb's and blkg */ 100 101 #ifdef CONFIG_CGROUP_WRITEBACK 102 struct backing_dev_info *__bdi; /* the associated bdi, set to NULL 103 * on bdi unregistration. For memcg-wb 104 * internal use only! */ 105 int blkcg_id; /* ID of the associated blkcg */ 106 struct rb_node rb_node; /* on bdi->cgwb_congestion_tree */ 107 #endif 108 }; 109 110 /* 111 * Each wb (bdi_writeback) can perform writeback operations, is measured 112 * and throttled, independently. Without cgroup writeback, each bdi 113 * (bdi_writeback) is served by its embedded bdi->wb. 114 * 115 * On the default hierarchy, blkcg implicitly enables memcg. This allows 116 * using memcg's page ownership for attributing writeback IOs, and every 117 * memcg - blkcg combination can be served by its own wb by assigning a 118 * dedicated wb to each memcg, which enables isolation across different 119 * cgroups and propagation of IO back pressure down from the IO layer upto 120 * the tasks which are generating the dirty pages to be written back. 121 * 122 * A cgroup wb is indexed on its bdi by the ID of the associated memcg, 123 * refcounted with the number of inodes attached to it, and pins the memcg 124 * and the corresponding blkcg. As the corresponding blkcg for a memcg may 125 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb 126 * is tested for blkcg after lookup and removed from index on mismatch so 127 * that a new wb for the combination can be created. 128 */ 129 struct bdi_writeback { 130 struct backing_dev_info *bdi; /* our parent bdi */ 131 132 unsigned long state; /* Always use atomic bitops on this */ 133 unsigned long last_old_flush; /* last old data flush */ 134 135 struct list_head b_dirty; /* dirty inodes */ 136 struct list_head b_io; /* parked for writeback */ 137 struct list_head b_more_io; /* parked for more writeback */ 138 struct list_head b_dirty_time; /* time stamps are dirty */ 139 spinlock_t list_lock; /* protects the b_* lists */ 140 141 struct percpu_counter stat[NR_WB_STAT_ITEMS]; 142 143 struct bdi_writeback_congested *congested; 144 145 unsigned long bw_time_stamp; /* last time write bw is updated */ 146 unsigned long dirtied_stamp; 147 unsigned long written_stamp; /* pages written at bw_time_stamp */ 148 unsigned long write_bandwidth; /* the estimated write bandwidth */ 149 unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */ 150 151 /* 152 * The base dirty throttle rate, re-calculated on every 200ms. 153 * All the bdi tasks' dirty rate will be curbed under it. 154 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 155 * in small steps and is much more smooth/stable than the latter. 156 */ 157 unsigned long dirty_ratelimit; 158 unsigned long balanced_dirty_ratelimit; 159 160 struct fprop_local_percpu completions; 161 int dirty_exceeded; 162 enum wb_reason start_all_reason; 163 164 spinlock_t work_lock; /* protects work_list & dwork scheduling */ 165 struct list_head work_list; 166 struct delayed_work dwork; /* work item used for writeback */ 167 168 unsigned long dirty_sleep; /* last wait */ 169 170 struct list_head bdi_node; /* anchored at bdi->wb_list */ 171 172 #ifdef CONFIG_CGROUP_WRITEBACK 173 struct percpu_ref refcnt; /* used only for !root wb's */ 174 struct fprop_local_percpu memcg_completions; 175 struct cgroup_subsys_state *memcg_css; /* the associated memcg */ 176 struct cgroup_subsys_state *blkcg_css; /* and blkcg */ 177 struct list_head memcg_node; /* anchored at memcg->cgwb_list */ 178 struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */ 179 180 union { 181 struct work_struct release_work; 182 struct rcu_head rcu; 183 }; 184 #endif 185 }; 186 187 struct backing_dev_info { 188 u64 id; 189 struct rb_node rb_node; /* keyed by ->id */ 190 struct list_head bdi_list; 191 unsigned long ra_pages; /* max readahead in PAGE_SIZE units */ 192 unsigned long io_pages; /* max allowed IO size */ 193 congested_fn *congested_fn; /* Function pointer if device is md/dm */ 194 void *congested_data; /* Pointer to aux data for congested func */ 195 196 struct kref refcnt; /* Reference counter for the structure */ 197 unsigned int capabilities; /* Device capabilities */ 198 unsigned int min_ratio; 199 unsigned int max_ratio, max_prop_frac; 200 201 /* 202 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are 203 * any dirty wbs, which is depended upon by bdi_has_dirty(). 204 */ 205 atomic_long_t tot_write_bandwidth; 206 207 struct bdi_writeback wb; /* the root writeback info for this bdi */ 208 struct list_head wb_list; /* list of all wbs */ 209 #ifdef CONFIG_CGROUP_WRITEBACK 210 struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */ 211 struct rb_root cgwb_congested_tree; /* their congested states */ 212 struct mutex cgwb_release_mutex; /* protect shutdown of wb structs */ 213 struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */ 214 #else 215 struct bdi_writeback_congested *wb_congested; 216 #endif 217 wait_queue_head_t wb_waitq; 218 219 struct device *dev; 220 char dev_name[64]; 221 struct device *owner; 222 223 struct timer_list laptop_mode_wb_timer; 224 225 #ifdef CONFIG_DEBUG_FS 226 struct dentry *debug_dir; 227 #endif 228 }; 229 230 enum { 231 BLK_RW_ASYNC = 0, 232 BLK_RW_SYNC = 1, 233 }; 234 235 void clear_wb_congested(struct bdi_writeback_congested *congested, int sync); 236 void set_wb_congested(struct bdi_writeback_congested *congested, int sync); 237 238 static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync) 239 { 240 clear_wb_congested(bdi->wb.congested, sync); 241 } 242 243 static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync) 244 { 245 set_wb_congested(bdi->wb.congested, sync); 246 } 247 248 struct wb_lock_cookie { 249 bool locked; 250 unsigned long flags; 251 }; 252 253 #ifdef CONFIG_CGROUP_WRITEBACK 254 255 /** 256 * wb_tryget - try to increment a wb's refcount 257 * @wb: bdi_writeback to get 258 */ 259 static inline bool wb_tryget(struct bdi_writeback *wb) 260 { 261 if (wb != &wb->bdi->wb) 262 return percpu_ref_tryget(&wb->refcnt); 263 return true; 264 } 265 266 /** 267 * wb_get - increment a wb's refcount 268 * @wb: bdi_writeback to get 269 */ 270 static inline void wb_get(struct bdi_writeback *wb) 271 { 272 if (wb != &wb->bdi->wb) 273 percpu_ref_get(&wb->refcnt); 274 } 275 276 /** 277 * wb_put - decrement a wb's refcount 278 * @wb: bdi_writeback to put 279 */ 280 static inline void wb_put(struct bdi_writeback *wb) 281 { 282 if (WARN_ON_ONCE(!wb->bdi)) { 283 /* 284 * A driver bug might cause a file to be removed before bdi was 285 * initialized. 286 */ 287 return; 288 } 289 290 if (wb != &wb->bdi->wb) 291 percpu_ref_put(&wb->refcnt); 292 } 293 294 /** 295 * wb_dying - is a wb dying? 296 * @wb: bdi_writeback of interest 297 * 298 * Returns whether @wb is unlinked and being drained. 299 */ 300 static inline bool wb_dying(struct bdi_writeback *wb) 301 { 302 return percpu_ref_is_dying(&wb->refcnt); 303 } 304 305 #else /* CONFIG_CGROUP_WRITEBACK */ 306 307 static inline bool wb_tryget(struct bdi_writeback *wb) 308 { 309 return true; 310 } 311 312 static inline void wb_get(struct bdi_writeback *wb) 313 { 314 } 315 316 static inline void wb_put(struct bdi_writeback *wb) 317 { 318 } 319 320 static inline bool wb_dying(struct bdi_writeback *wb) 321 { 322 return false; 323 } 324 325 #endif /* CONFIG_CGROUP_WRITEBACK */ 326 327 #endif /* __LINUX_BACKING_DEV_DEFS_H */ 328