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