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_shutting_down, /* wb_shutdown() in progress */ 26 WB_writeback_running, /* Writeback is in progress */ 27 WB_has_dirty_io, /* Dirty inodes on ->b_{dirty|io|more_io} */ 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 * For cgroup writeback, multiple wb's may map to the same blkcg. Those 49 * wb's can operate mostly independently but should share the congested 50 * state. To facilitate such sharing, the congested state is tracked using 51 * the following struct which is created on demand, indexed by blkcg ID on 52 * its bdi, and refcounted. 53 */ 54 struct bdi_writeback_congested { 55 unsigned long state; /* WB_[a]sync_congested flags */ 56 atomic_t refcnt; /* nr of attached wb's and blkg */ 57 58 #ifdef CONFIG_CGROUP_WRITEBACK 59 struct backing_dev_info *__bdi; /* the associated bdi, set to NULL 60 * on bdi unregistration. For memcg-wb 61 * internal use only! */ 62 int blkcg_id; /* ID of the associated blkcg */ 63 struct rb_node rb_node; /* on bdi->cgwb_congestion_tree */ 64 #endif 65 }; 66 67 /* 68 * Each wb (bdi_writeback) can perform writeback operations, is measured 69 * and throttled, independently. Without cgroup writeback, each bdi 70 * (bdi_writeback) is served by its embedded bdi->wb. 71 * 72 * On the default hierarchy, blkcg implicitly enables memcg. This allows 73 * using memcg's page ownership for attributing writeback IOs, and every 74 * memcg - blkcg combination can be served by its own wb by assigning a 75 * dedicated wb to each memcg, which enables isolation across different 76 * cgroups and propagation of IO back pressure down from the IO layer upto 77 * the tasks which are generating the dirty pages to be written back. 78 * 79 * A cgroup wb is indexed on its bdi by the ID of the associated memcg, 80 * refcounted with the number of inodes attached to it, and pins the memcg 81 * and the corresponding blkcg. As the corresponding blkcg for a memcg may 82 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb 83 * is tested for blkcg after lookup and removed from index on mismatch so 84 * that a new wb for the combination can be created. 85 */ 86 struct bdi_writeback { 87 struct backing_dev_info *bdi; /* our parent bdi */ 88 89 unsigned long state; /* Always use atomic bitops on this */ 90 unsigned long last_old_flush; /* last old data flush */ 91 92 struct list_head b_dirty; /* dirty inodes */ 93 struct list_head b_io; /* parked for writeback */ 94 struct list_head b_more_io; /* parked for more writeback */ 95 struct list_head b_dirty_time; /* time stamps are dirty */ 96 spinlock_t list_lock; /* protects the b_* lists */ 97 98 struct percpu_counter stat[NR_WB_STAT_ITEMS]; 99 100 struct bdi_writeback_congested *congested; 101 102 unsigned long bw_time_stamp; /* last time write bw is updated */ 103 unsigned long dirtied_stamp; 104 unsigned long written_stamp; /* pages written at bw_time_stamp */ 105 unsigned long write_bandwidth; /* the estimated write bandwidth */ 106 unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */ 107 108 /* 109 * The base dirty throttle rate, re-calculated on every 200ms. 110 * All the bdi tasks' dirty rate will be curbed under it. 111 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 112 * in small steps and is much more smooth/stable than the latter. 113 */ 114 unsigned long dirty_ratelimit; 115 unsigned long balanced_dirty_ratelimit; 116 117 struct fprop_local_percpu completions; 118 int dirty_exceeded; 119 120 spinlock_t work_lock; /* protects work_list & dwork scheduling */ 121 struct list_head work_list; 122 struct delayed_work dwork; /* work item used for writeback */ 123 124 unsigned long dirty_sleep; /* last wait */ 125 126 struct list_head bdi_node; /* anchored at bdi->wb_list */ 127 128 #ifdef CONFIG_CGROUP_WRITEBACK 129 struct percpu_ref refcnt; /* used only for !root wb's */ 130 struct fprop_local_percpu memcg_completions; 131 struct cgroup_subsys_state *memcg_css; /* the associated memcg */ 132 struct cgroup_subsys_state *blkcg_css; /* and blkcg */ 133 struct list_head memcg_node; /* anchored at memcg->cgwb_list */ 134 struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */ 135 136 union { 137 struct work_struct release_work; 138 struct rcu_head rcu; 139 }; 140 #endif 141 }; 142 143 struct backing_dev_info { 144 struct list_head bdi_list; 145 unsigned long ra_pages; /* max readahead in PAGE_SIZE units */ 146 unsigned long io_pages; /* max allowed IO size */ 147 congested_fn *congested_fn; /* Function pointer if device is md/dm */ 148 void *congested_data; /* Pointer to aux data for congested func */ 149 150 const char *name; 151 152 struct kref refcnt; /* Reference counter for the structure */ 153 unsigned int capabilities; /* Device capabilities */ 154 unsigned int min_ratio; 155 unsigned int max_ratio, max_prop_frac; 156 157 /* 158 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are 159 * any dirty wbs, which is depended upon by bdi_has_dirty(). 160 */ 161 atomic_long_t tot_write_bandwidth; 162 163 struct bdi_writeback wb; /* the root writeback info for this bdi */ 164 struct list_head wb_list; /* list of all wbs */ 165 #ifdef CONFIG_CGROUP_WRITEBACK 166 struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */ 167 struct rb_root cgwb_congested_tree; /* their congested states */ 168 #else 169 struct bdi_writeback_congested *wb_congested; 170 #endif 171 wait_queue_head_t wb_waitq; 172 173 struct device *dev; 174 struct device *owner; 175 176 struct timer_list laptop_mode_wb_timer; 177 178 #ifdef CONFIG_DEBUG_FS 179 struct dentry *debug_dir; 180 struct dentry *debug_stats; 181 #endif 182 }; 183 184 enum { 185 BLK_RW_ASYNC = 0, 186 BLK_RW_SYNC = 1, 187 }; 188 189 void clear_wb_congested(struct bdi_writeback_congested *congested, int sync); 190 void set_wb_congested(struct bdi_writeback_congested *congested, int sync); 191 192 static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync) 193 { 194 clear_wb_congested(bdi->wb.congested, sync); 195 } 196 197 static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync) 198 { 199 set_wb_congested(bdi->wb.congested, sync); 200 } 201 202 #ifdef CONFIG_CGROUP_WRITEBACK 203 204 /** 205 * wb_tryget - try to increment a wb's refcount 206 * @wb: bdi_writeback to get 207 */ 208 static inline bool wb_tryget(struct bdi_writeback *wb) 209 { 210 if (wb != &wb->bdi->wb) 211 return percpu_ref_tryget(&wb->refcnt); 212 return true; 213 } 214 215 /** 216 * wb_get - increment a wb's refcount 217 * @wb: bdi_writeback to get 218 */ 219 static inline void wb_get(struct bdi_writeback *wb) 220 { 221 if (wb != &wb->bdi->wb) 222 percpu_ref_get(&wb->refcnt); 223 } 224 225 /** 226 * wb_put - decrement a wb's refcount 227 * @wb: bdi_writeback to put 228 */ 229 static inline void wb_put(struct bdi_writeback *wb) 230 { 231 if (wb != &wb->bdi->wb) 232 percpu_ref_put(&wb->refcnt); 233 } 234 235 /** 236 * wb_dying - is a wb dying? 237 * @wb: bdi_writeback of interest 238 * 239 * Returns whether @wb is unlinked and being drained. 240 */ 241 static inline bool wb_dying(struct bdi_writeback *wb) 242 { 243 return percpu_ref_is_dying(&wb->refcnt); 244 } 245 246 #else /* CONFIG_CGROUP_WRITEBACK */ 247 248 static inline bool wb_tryget(struct bdi_writeback *wb) 249 { 250 return true; 251 } 252 253 static inline void wb_get(struct bdi_writeback *wb) 254 { 255 } 256 257 static inline void wb_put(struct bdi_writeback *wb) 258 { 259 } 260 261 static inline bool wb_dying(struct bdi_writeback *wb) 262 { 263 return false; 264 } 265 266 #endif /* CONFIG_CGROUP_WRITEBACK */ 267 268 #endif /* __LINUX_BACKING_DEV_DEFS_H */ 269