1 #ifndef __LINUX_BACKING_DEV_DEFS_H 2 #define __LINUX_BACKING_DEV_DEFS_H 3 4 #include <linux/list.h> 5 #include <linux/radix-tree.h> 6 #include <linux/rbtree.h> 7 #include <linux/spinlock.h> 8 #include <linux/percpu_counter.h> 9 #include <linux/percpu-refcount.h> 10 #include <linux/flex_proportions.h> 11 #include <linux/timer.h> 12 #include <linux/workqueue.h> 13 #include <linux/kref.h> 14 15 struct page; 16 struct device; 17 struct dentry; 18 19 /* 20 * Bits in bdi_writeback.state 21 */ 22 enum wb_state { 23 WB_registered, /* bdi_register() was done */ 24 WB_writeback_running, /* Writeback is in progress */ 25 WB_has_dirty_io, /* Dirty inodes on ->b_{dirty|io|more_io} */ 26 }; 27 28 enum wb_congested_state { 29 WB_async_congested, /* The async (write) queue is getting full */ 30 WB_sync_congested, /* The sync queue is getting full */ 31 }; 32 33 typedef int (congested_fn)(void *, int); 34 35 enum wb_stat_item { 36 WB_RECLAIMABLE, 37 WB_WRITEBACK, 38 WB_DIRTIED, 39 WB_WRITTEN, 40 NR_WB_STAT_ITEMS 41 }; 42 43 #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 44 45 /* 46 * For cgroup writeback, multiple wb's may map to the same blkcg. Those 47 * wb's can operate mostly independently but should share the congested 48 * state. To facilitate such sharing, the congested state is tracked using 49 * the following struct which is created on demand, indexed by blkcg ID on 50 * its bdi, and refcounted. 51 */ 52 struct bdi_writeback_congested { 53 unsigned long state; /* WB_[a]sync_congested flags */ 54 atomic_t refcnt; /* nr of attached wb's and blkg */ 55 56 #ifdef CONFIG_CGROUP_WRITEBACK 57 struct backing_dev_info *bdi; /* the associated bdi */ 58 int blkcg_id; /* ID of the associated blkcg */ 59 struct rb_node rb_node; /* on bdi->cgwb_congestion_tree */ 60 #endif 61 }; 62 63 /* 64 * Each wb (bdi_writeback) can perform writeback operations, is measured 65 * and throttled, independently. Without cgroup writeback, each bdi 66 * (bdi_writeback) is served by its embedded bdi->wb. 67 * 68 * On the default hierarchy, blkcg implicitly enables memcg. This allows 69 * using memcg's page ownership for attributing writeback IOs, and every 70 * memcg - blkcg combination can be served by its own wb by assigning a 71 * dedicated wb to each memcg, which enables isolation across different 72 * cgroups and propagation of IO back pressure down from the IO layer upto 73 * the tasks which are generating the dirty pages to be written back. 74 * 75 * A cgroup wb is indexed on its bdi by the ID of the associated memcg, 76 * refcounted with the number of inodes attached to it, and pins the memcg 77 * and the corresponding blkcg. As the corresponding blkcg for a memcg may 78 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb 79 * is tested for blkcg after lookup and removed from index on mismatch so 80 * that a new wb for the combination can be created. 81 */ 82 struct bdi_writeback { 83 struct backing_dev_info *bdi; /* our parent bdi */ 84 85 unsigned long state; /* Always use atomic bitops on this */ 86 unsigned long last_old_flush; /* last old data flush */ 87 88 struct list_head b_dirty; /* dirty inodes */ 89 struct list_head b_io; /* parked for writeback */ 90 struct list_head b_more_io; /* parked for more writeback */ 91 struct list_head b_dirty_time; /* time stamps are dirty */ 92 spinlock_t list_lock; /* protects the b_* lists */ 93 94 struct percpu_counter stat[NR_WB_STAT_ITEMS]; 95 96 struct bdi_writeback_congested *congested; 97 98 unsigned long bw_time_stamp; /* last time write bw is updated */ 99 unsigned long dirtied_stamp; 100 unsigned long written_stamp; /* pages written at bw_time_stamp */ 101 unsigned long write_bandwidth; /* the estimated write bandwidth */ 102 unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */ 103 104 /* 105 * The base dirty throttle rate, re-calculated on every 200ms. 106 * All the bdi tasks' dirty rate will be curbed under it. 107 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 108 * in small steps and is much more smooth/stable than the latter. 109 */ 110 unsigned long dirty_ratelimit; 111 unsigned long balanced_dirty_ratelimit; 112 113 struct fprop_local_percpu completions; 114 int dirty_exceeded; 115 116 spinlock_t work_lock; /* protects work_list & dwork scheduling */ 117 struct list_head work_list; 118 struct delayed_work dwork; /* work item used for writeback */ 119 120 unsigned long dirty_sleep; /* last wait */ 121 122 struct list_head bdi_node; /* anchored at bdi->wb_list */ 123 124 #ifdef CONFIG_CGROUP_WRITEBACK 125 struct percpu_ref refcnt; /* used only for !root wb's */ 126 struct fprop_local_percpu memcg_completions; 127 struct cgroup_subsys_state *memcg_css; /* the associated memcg */ 128 struct cgroup_subsys_state *blkcg_css; /* and blkcg */ 129 struct list_head memcg_node; /* anchored at memcg->cgwb_list */ 130 struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */ 131 132 union { 133 struct work_struct release_work; 134 struct rcu_head rcu; 135 }; 136 #endif 137 }; 138 139 struct backing_dev_info { 140 struct list_head bdi_list; 141 unsigned long ra_pages; /* max readahead in PAGE_SIZE units */ 142 unsigned long io_pages; /* max allowed IO size */ 143 congested_fn *congested_fn; /* Function pointer if device is md/dm */ 144 void *congested_data; /* Pointer to aux data for congested func */ 145 146 char *name; 147 148 struct kref refcnt; /* Reference counter for the structure */ 149 unsigned int capabilities; /* Device capabilities */ 150 unsigned int min_ratio; 151 unsigned int max_ratio, max_prop_frac; 152 153 /* 154 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are 155 * any dirty wbs, which is depended upon by bdi_has_dirty(). 156 */ 157 atomic_long_t tot_write_bandwidth; 158 159 struct bdi_writeback wb; /* the root writeback info for this bdi */ 160 struct list_head wb_list; /* list of all wbs */ 161 #ifdef CONFIG_CGROUP_WRITEBACK 162 struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */ 163 struct rb_root cgwb_congested_tree; /* their congested states */ 164 atomic_t usage_cnt; /* counts both cgwbs and cgwb_contested's */ 165 #else 166 struct bdi_writeback_congested *wb_congested; 167 #endif 168 wait_queue_head_t wb_waitq; 169 170 struct device *dev; 171 struct device *owner; 172 173 struct timer_list laptop_mode_wb_timer; 174 175 #ifdef CONFIG_DEBUG_FS 176 struct dentry *debug_dir; 177 struct dentry *debug_stats; 178 #endif 179 }; 180 181 enum { 182 BLK_RW_ASYNC = 0, 183 BLK_RW_SYNC = 1, 184 }; 185 186 void clear_wb_congested(struct bdi_writeback_congested *congested, int sync); 187 void set_wb_congested(struct bdi_writeback_congested *congested, int sync); 188 189 static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync) 190 { 191 clear_wb_congested(bdi->wb.congested, sync); 192 } 193 194 static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync) 195 { 196 set_wb_congested(bdi->wb.congested, sync); 197 } 198 199 #ifdef CONFIG_CGROUP_WRITEBACK 200 201 /** 202 * wb_tryget - try to increment a wb's refcount 203 * @wb: bdi_writeback to get 204 */ 205 static inline bool wb_tryget(struct bdi_writeback *wb) 206 { 207 if (wb != &wb->bdi->wb) 208 return percpu_ref_tryget(&wb->refcnt); 209 return true; 210 } 211 212 /** 213 * wb_get - increment a wb's refcount 214 * @wb: bdi_writeback to get 215 */ 216 static inline void wb_get(struct bdi_writeback *wb) 217 { 218 if (wb != &wb->bdi->wb) 219 percpu_ref_get(&wb->refcnt); 220 } 221 222 /** 223 * wb_put - decrement a wb's refcount 224 * @wb: bdi_writeback to put 225 */ 226 static inline void wb_put(struct bdi_writeback *wb) 227 { 228 if (wb != &wb->bdi->wb) 229 percpu_ref_put(&wb->refcnt); 230 } 231 232 /** 233 * wb_dying - is a wb dying? 234 * @wb: bdi_writeback of interest 235 * 236 * Returns whether @wb is unlinked and being drained. 237 */ 238 static inline bool wb_dying(struct bdi_writeback *wb) 239 { 240 return percpu_ref_is_dying(&wb->refcnt); 241 } 242 243 #else /* CONFIG_CGROUP_WRITEBACK */ 244 245 static inline bool wb_tryget(struct bdi_writeback *wb) 246 { 247 return true; 248 } 249 250 static inline void wb_get(struct bdi_writeback *wb) 251 { 252 } 253 254 static inline void wb_put(struct bdi_writeback *wb) 255 { 256 } 257 258 static inline bool wb_dying(struct bdi_writeback *wb) 259 { 260 return false; 261 } 262 263 #endif /* CONFIG_CGROUP_WRITEBACK */ 264 265 #endif /* __LINUX_BACKING_DEV_DEFS_H */ 266