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 16 struct page; 17 struct device; 18 struct dentry; 19 20 /* 21 * Bits in bdi_writeback.state 22 */ 23 enum wb_state { 24 WB_registered, /* bdi_register() was done */ 25 WB_writeback_running, /* Writeback is in progress */ 26 WB_has_dirty_io, /* Dirty inodes on ->b_{dirty|io|more_io} */ 27 WB_start_all, /* nr_pages == 0 (all) work pending */ 28 }; 29 30 enum wb_congested_state { 31 WB_async_congested, /* The async (write) queue is getting full */ 32 WB_sync_congested, /* The sync queue is getting full */ 33 }; 34 35 typedef int (congested_fn)(void *, int); 36 37 enum wb_stat_item { 38 WB_RECLAIMABLE, 39 WB_WRITEBACK, 40 WB_DIRTIED, 41 WB_WRITTEN, 42 NR_WB_STAT_ITEMS 43 }; 44 45 #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 46 47 /* 48 * why some writeback work was initiated 49 */ 50 enum wb_reason { 51 WB_REASON_BACKGROUND, 52 WB_REASON_VMSCAN, 53 WB_REASON_SYNC, 54 WB_REASON_PERIODIC, 55 WB_REASON_LAPTOP_TIMER, 56 WB_REASON_FREE_MORE_MEM, 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 66 WB_REASON_MAX, 67 }; 68 69 /* 70 * For cgroup writeback, multiple wb's may map to the same blkcg. Those 71 * wb's can operate mostly independently but should share the congested 72 * state. To facilitate such sharing, the congested state is tracked using 73 * the following struct which is created on demand, indexed by blkcg ID on 74 * its bdi, and refcounted. 75 */ 76 struct bdi_writeback_congested { 77 unsigned long state; /* WB_[a]sync_congested flags */ 78 atomic_t refcnt; /* nr of attached wb's and blkg */ 79 80 #ifdef CONFIG_CGROUP_WRITEBACK 81 struct backing_dev_info *__bdi; /* the associated bdi, set to NULL 82 * on bdi unregistration. For memcg-wb 83 * internal use only! */ 84 int blkcg_id; /* ID of the associated blkcg */ 85 struct rb_node rb_node; /* on bdi->cgwb_congestion_tree */ 86 #endif 87 }; 88 89 /* 90 * Each wb (bdi_writeback) can perform writeback operations, is measured 91 * and throttled, independently. Without cgroup writeback, each bdi 92 * (bdi_writeback) is served by its embedded bdi->wb. 93 * 94 * On the default hierarchy, blkcg implicitly enables memcg. This allows 95 * using memcg's page ownership for attributing writeback IOs, and every 96 * memcg - blkcg combination can be served by its own wb by assigning a 97 * dedicated wb to each memcg, which enables isolation across different 98 * cgroups and propagation of IO back pressure down from the IO layer upto 99 * the tasks which are generating the dirty pages to be written back. 100 * 101 * A cgroup wb is indexed on its bdi by the ID of the associated memcg, 102 * refcounted with the number of inodes attached to it, and pins the memcg 103 * and the corresponding blkcg. As the corresponding blkcg for a memcg may 104 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb 105 * is tested for blkcg after lookup and removed from index on mismatch so 106 * that a new wb for the combination can be created. 107 */ 108 struct bdi_writeback { 109 struct backing_dev_info *bdi; /* our parent bdi */ 110 111 unsigned long state; /* Always use atomic bitops on this */ 112 unsigned long last_old_flush; /* last old data flush */ 113 114 struct list_head b_dirty; /* dirty inodes */ 115 struct list_head b_io; /* parked for writeback */ 116 struct list_head b_more_io; /* parked for more writeback */ 117 struct list_head b_dirty_time; /* time stamps are dirty */ 118 spinlock_t list_lock; /* protects the b_* lists */ 119 120 struct percpu_counter stat[NR_WB_STAT_ITEMS]; 121 122 struct bdi_writeback_congested *congested; 123 124 unsigned long bw_time_stamp; /* last time write bw is updated */ 125 unsigned long dirtied_stamp; 126 unsigned long written_stamp; /* pages written at bw_time_stamp */ 127 unsigned long write_bandwidth; /* the estimated write bandwidth */ 128 unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */ 129 130 /* 131 * The base dirty throttle rate, re-calculated on every 200ms. 132 * All the bdi tasks' dirty rate will be curbed under it. 133 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 134 * in small steps and is much more smooth/stable than the latter. 135 */ 136 unsigned long dirty_ratelimit; 137 unsigned long balanced_dirty_ratelimit; 138 139 struct fprop_local_percpu completions; 140 int dirty_exceeded; 141 enum wb_reason start_all_reason; 142 143 spinlock_t work_lock; /* protects work_list & dwork scheduling */ 144 struct list_head work_list; 145 struct delayed_work dwork; /* work item used for writeback */ 146 147 unsigned long dirty_sleep; /* last wait */ 148 149 struct list_head bdi_node; /* anchored at bdi->wb_list */ 150 151 #ifdef CONFIG_CGROUP_WRITEBACK 152 struct percpu_ref refcnt; /* used only for !root wb's */ 153 struct fprop_local_percpu memcg_completions; 154 struct cgroup_subsys_state *memcg_css; /* the associated memcg */ 155 struct cgroup_subsys_state *blkcg_css; /* and blkcg */ 156 struct list_head memcg_node; /* anchored at memcg->cgwb_list */ 157 struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */ 158 159 union { 160 struct work_struct release_work; 161 struct rcu_head rcu; 162 }; 163 #endif 164 }; 165 166 struct backing_dev_info { 167 struct list_head bdi_list; 168 unsigned long ra_pages; /* max readahead in PAGE_SIZE units */ 169 unsigned long io_pages; /* max allowed IO size */ 170 congested_fn *congested_fn; /* Function pointer if device is md/dm */ 171 void *congested_data; /* Pointer to aux data for congested func */ 172 173 const char *name; 174 175 struct kref refcnt; /* Reference counter for the structure */ 176 unsigned int capabilities; /* Device capabilities */ 177 unsigned int min_ratio; 178 unsigned int max_ratio, max_prop_frac; 179 180 /* 181 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are 182 * any dirty wbs, which is depended upon by bdi_has_dirty(). 183 */ 184 atomic_long_t tot_write_bandwidth; 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 rb_root cgwb_congested_tree; /* their congested states */ 191 struct mutex cgwb_release_mutex; /* protect shutdown of wb structs */ 192 #else 193 struct bdi_writeback_congested *wb_congested; 194 #endif 195 wait_queue_head_t wb_waitq; 196 197 struct device *dev; 198 struct device *owner; 199 200 struct timer_list laptop_mode_wb_timer; 201 202 #ifdef CONFIG_DEBUG_FS 203 struct dentry *debug_dir; 204 struct dentry *debug_stats; 205 #endif 206 }; 207 208 enum { 209 BLK_RW_ASYNC = 0, 210 BLK_RW_SYNC = 1, 211 }; 212 213 void clear_wb_congested(struct bdi_writeback_congested *congested, int sync); 214 void set_wb_congested(struct bdi_writeback_congested *congested, int sync); 215 216 static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync) 217 { 218 clear_wb_congested(bdi->wb.congested, sync); 219 } 220 221 static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync) 222 { 223 set_wb_congested(bdi->wb.congested, sync); 224 } 225 226 struct wb_lock_cookie { 227 bool locked; 228 unsigned long flags; 229 }; 230 231 #ifdef CONFIG_CGROUP_WRITEBACK 232 233 /** 234 * wb_tryget - try to increment a wb's refcount 235 * @wb: bdi_writeback to get 236 */ 237 static inline bool wb_tryget(struct bdi_writeback *wb) 238 { 239 if (wb != &wb->bdi->wb) 240 return percpu_ref_tryget(&wb->refcnt); 241 return true; 242 } 243 244 /** 245 * wb_get - increment a wb's refcount 246 * @wb: bdi_writeback to get 247 */ 248 static inline void wb_get(struct bdi_writeback *wb) 249 { 250 if (wb != &wb->bdi->wb) 251 percpu_ref_get(&wb->refcnt); 252 } 253 254 /** 255 * wb_put - decrement a wb's refcount 256 * @wb: bdi_writeback to put 257 */ 258 static inline void wb_put(struct bdi_writeback *wb) 259 { 260 if (wb != &wb->bdi->wb) 261 percpu_ref_put(&wb->refcnt); 262 } 263 264 /** 265 * wb_dying - is a wb dying? 266 * @wb: bdi_writeback of interest 267 * 268 * Returns whether @wb is unlinked and being drained. 269 */ 270 static inline bool wb_dying(struct bdi_writeback *wb) 271 { 272 return percpu_ref_is_dying(&wb->refcnt); 273 } 274 275 #else /* CONFIG_CGROUP_WRITEBACK */ 276 277 static inline bool wb_tryget(struct bdi_writeback *wb) 278 { 279 return true; 280 } 281 282 static inline void wb_get(struct bdi_writeback *wb) 283 { 284 } 285 286 static inline void wb_put(struct bdi_writeback *wb) 287 { 288 } 289 290 static inline bool wb_dying(struct bdi_writeback *wb) 291 { 292 return false; 293 } 294 295 #endif /* CONFIG_CGROUP_WRITEBACK */ 296 297 #endif /* __LINUX_BACKING_DEV_DEFS_H */ 298