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