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_stat_item { 32 WB_RECLAIMABLE, 33 WB_WRITEBACK, 34 WB_DIRTIED, 35 WB_WRITTEN, 36 NR_WB_STAT_ITEMS 37 }; 38 39 #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 40 41 /* 42 * why some writeback work was initiated 43 */ 44 enum wb_reason { 45 WB_REASON_BACKGROUND, 46 WB_REASON_VMSCAN, 47 WB_REASON_SYNC, 48 WB_REASON_PERIODIC, 49 WB_REASON_LAPTOP_TIMER, 50 WB_REASON_FS_FREE_SPACE, 51 /* 52 * There is no bdi forker thread any more and works are done 53 * by emergency worker, however, this is TPs userland visible 54 * and we'll be exposing exactly the same information, 55 * so it has a mismatch name. 56 */ 57 WB_REASON_FORKER_THREAD, 58 WB_REASON_FOREIGN_FLUSH, 59 60 WB_REASON_MAX, 61 }; 62 63 struct wb_completion { 64 atomic_t cnt; 65 wait_queue_head_t *waitq; 66 unsigned long progress_stamp; /* The jiffies when slow progress is detected */ 67 unsigned long wait_start; /* The jiffies when waiting for the writeback work to finish */ 68 }; 69 70 #define __WB_COMPLETION_INIT(_waitq) \ 71 (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) } 72 73 /* 74 * If one wants to wait for one or more wb_writeback_works, each work's 75 * ->done should be set to a wb_completion defined using the following 76 * macro. Once all work items are issued with wb_queue_work(), the caller 77 * can wait for the completion of all using wb_wait_for_completion(). Work 78 * items which are waited upon aren't freed automatically on completion. 79 */ 80 #define WB_COMPLETION_INIT(bdi) __WB_COMPLETION_INIT(&(bdi)->wb_waitq) 81 82 #define DEFINE_WB_COMPLETION(cmpl, bdi) \ 83 struct wb_completion cmpl = WB_COMPLETION_INIT(bdi) 84 85 /* 86 * Each wb (bdi_writeback) can perform writeback operations, is measured 87 * and throttled, independently. Without cgroup writeback, each bdi 88 * (bdi_writeback) is served by its embedded bdi->wb. 89 * 90 * On the default hierarchy, blkcg implicitly enables memcg. This allows 91 * using memcg's page ownership for attributing writeback IOs, and every 92 * memcg - blkcg combination can be served by its own wb by assigning a 93 * dedicated wb to each memcg, which enables isolation across different 94 * cgroups and propagation of IO back pressure down from the IO layer upto 95 * the tasks which are generating the dirty pages to be written back. 96 * 97 * A cgroup wb is indexed on its bdi by the ID of the associated memcg, 98 * refcounted with the number of inodes attached to it, and pins the memcg 99 * and the corresponding blkcg. As the corresponding blkcg for a memcg may 100 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb 101 * is tested for blkcg after lookup and removed from index on mismatch so 102 * that a new wb for the combination can be created. 103 * 104 * Each bdi_writeback that is not embedded into the backing_dev_info must hold 105 * a reference to the parent backing_dev_info. See cgwb_create() for details. 106 */ 107 struct bdi_writeback { 108 struct backing_dev_info *bdi; /* our parent bdi */ 109 110 unsigned long state; /* Always use atomic bitops on this */ 111 unsigned long last_old_flush; /* last old data flush */ 112 113 struct list_head b_dirty; /* dirty inodes */ 114 struct list_head b_io; /* parked for writeback */ 115 struct list_head b_more_io; /* parked for more writeback */ 116 struct list_head b_dirty_time; /* time stamps are dirty */ 117 spinlock_t list_lock; /* protects the b_* lists */ 118 119 atomic_t writeback_inodes; /* number of inodes under writeback */ 120 struct percpu_counter stat[NR_WB_STAT_ITEMS]; 121 122 unsigned long bw_time_stamp; /* last time write bw is updated */ 123 unsigned long dirtied_stamp; 124 unsigned long written_stamp; /* pages written at bw_time_stamp */ 125 unsigned long write_bandwidth; /* the estimated write bandwidth */ 126 unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */ 127 128 /* 129 * The base dirty throttle rate, re-calculated on every 200ms. 130 * All the bdi tasks' dirty rate will be curbed under it. 131 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 132 * in small steps and is much more smooth/stable than the latter. 133 */ 134 unsigned long dirty_ratelimit; 135 unsigned long balanced_dirty_ratelimit; 136 137 struct fprop_local_percpu completions; 138 int dirty_exceeded; 139 enum wb_reason start_all_reason; 140 141 spinlock_t work_lock; /* protects work_list & dwork scheduling */ 142 struct list_head work_list; 143 struct delayed_work dwork; /* work item used for writeback */ 144 struct delayed_work bw_dwork; /* work item used for bandwidth estimate */ 145 146 struct list_head bdi_node; /* anchored at bdi->wb_list */ 147 148 #ifdef CONFIG_CGROUP_WRITEBACK 149 struct percpu_ref refcnt; /* used only for !root wb's */ 150 struct fprop_local_percpu memcg_completions; 151 struct cgroup_subsys_state *memcg_css; /* the associated memcg */ 152 struct cgroup_subsys_state *blkcg_css; /* and blkcg */ 153 struct list_head memcg_node; /* anchored at memcg->cgwb_list */ 154 struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */ 155 struct list_head b_attached; /* attached inodes, protected by list_lock */ 156 struct list_head offline_node; /* anchored at offline_cgwbs */ 157 struct work_struct switch_work; /* work used to perform inode switching 158 * to this wb */ 159 struct llist_head switch_wbs_ctxs; /* queued contexts for 160 * writeback switching */ 161 162 union { 163 struct work_struct release_work; 164 struct rcu_head rcu; 165 }; 166 #endif 167 }; 168 169 struct backing_dev_info { 170 u64 id; 171 struct rb_node rb_node; /* keyed by ->id */ 172 struct list_head bdi_list; 173 /* max readahead in PAGE_SIZE units */ 174 unsigned long __data_racy ra_pages; 175 176 unsigned long io_pages; /* max allowed IO size */ 177 178 struct kref refcnt; /* Reference counter for the structure */ 179 unsigned int capabilities; /* Device capabilities */ 180 unsigned int min_ratio; 181 unsigned int max_ratio, max_prop_frac; 182 183 /* 184 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are 185 * any dirty wbs, which is depended upon by bdi_has_dirty(). 186 */ 187 atomic_long_t tot_write_bandwidth; 188 /* 189 * Jiffies when last process was dirty throttled on this bdi. Used by 190 * blk-wbt. 191 */ 192 unsigned long last_bdp_sleep; 193 194 struct bdi_writeback wb; /* the root writeback info for this bdi */ 195 struct list_head wb_list; /* list of all wbs */ 196 #ifdef CONFIG_CGROUP_WRITEBACK 197 struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */ 198 struct mutex cgwb_release_mutex; /* protect shutdown of wb structs */ 199 struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */ 200 #endif 201 wait_queue_head_t wb_waitq; 202 203 struct device *dev; 204 char dev_name[64]; 205 struct device *owner; 206 207 struct timer_list laptop_mode_wb_timer; 208 209 #ifdef CONFIG_DEBUG_FS 210 struct dentry *debug_dir; 211 #endif 212 }; 213 214 struct wb_lock_cookie { 215 bool locked; 216 unsigned long flags; 217 }; 218 219 #ifdef CONFIG_CGROUP_WRITEBACK 220 221 /** 222 * wb_tryget - try to increment a wb's refcount 223 * @wb: bdi_writeback to get 224 */ 225 static inline bool wb_tryget(struct bdi_writeback *wb) 226 { 227 if (wb != &wb->bdi->wb) 228 return percpu_ref_tryget(&wb->refcnt); 229 return true; 230 } 231 232 /** 233 * wb_get - increment a wb's refcount 234 * @wb: bdi_writeback to get 235 */ 236 static inline void wb_get(struct bdi_writeback *wb) 237 { 238 if (wb != &wb->bdi->wb) 239 percpu_ref_get(&wb->refcnt); 240 } 241 242 /** 243 * wb_put - decrement a wb's refcount 244 * @wb: bdi_writeback to put 245 * @nr: number of references to put 246 */ 247 static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr) 248 { 249 if (WARN_ON_ONCE(!wb->bdi)) { 250 /* 251 * A driver bug might cause a file to be removed before bdi was 252 * initialized. 253 */ 254 return; 255 } 256 257 if (wb != &wb->bdi->wb) 258 percpu_ref_put_many(&wb->refcnt, nr); 259 } 260 261 /** 262 * wb_put - decrement a wb's refcount 263 * @wb: bdi_writeback to put 264 */ 265 static inline void wb_put(struct bdi_writeback *wb) 266 { 267 wb_put_many(wb, 1); 268 } 269 270 /** 271 * wb_dying - is a wb dying? 272 * @wb: bdi_writeback of interest 273 * 274 * Returns whether @wb is unlinked and being drained. 275 */ 276 static inline bool wb_dying(struct bdi_writeback *wb) 277 { 278 return percpu_ref_is_dying(&wb->refcnt); 279 } 280 281 #else /* CONFIG_CGROUP_WRITEBACK */ 282 283 static inline bool wb_tryget(struct bdi_writeback *wb) 284 { 285 return true; 286 } 287 288 static inline void wb_get(struct bdi_writeback *wb) 289 { 290 } 291 292 static inline void wb_put(struct bdi_writeback *wb) 293 { 294 } 295 296 static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr) 297 { 298 } 299 300 static inline bool wb_dying(struct bdi_writeback *wb) 301 { 302 return false; 303 } 304 305 #endif /* CONFIG_CGROUP_WRITEBACK */ 306 307 #endif /* __LINUX_BACKING_DEV_DEFS_H */ 308