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