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_congested_state {
32 WB_async_congested, /* The async (write) queue is getting full */
33 WB_sync_congested, /* The sync queue is getting full */
34 };
35
36 enum wb_stat_item {
37 WB_RECLAIMABLE,
38 WB_WRITEBACK,
39 WB_DIRTIED,
40 WB_WRITTEN,
41 NR_WB_STAT_ITEMS
42 };
43
44 #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
45
46 /*
47 * why some writeback work was initiated
48 */
49 enum wb_reason {
50 WB_REASON_BACKGROUND,
51 WB_REASON_VMSCAN,
52 WB_REASON_SYNC,
53 WB_REASON_PERIODIC,
54 WB_REASON_LAPTOP_TIMER,
55 WB_REASON_FS_FREE_SPACE,
56 /*
57 * There is no bdi forker thread any more and works are done
58 * by emergency worker, however, this is TPs userland visible
59 * and we'll be exposing exactly the same information,
60 * so it has a mismatch name.
61 */
62 WB_REASON_FORKER_THREAD,
63 WB_REASON_FOREIGN_FLUSH,
64
65 WB_REASON_MAX,
66 };
67
68 struct wb_completion {
69 atomic_t cnt;
70 wait_queue_head_t *waitq;
71 };
72
73 #define __WB_COMPLETION_INIT(_waitq) \
74 (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) }
75
76 /*
77 * If one wants to wait for one or more wb_writeback_works, each work's
78 * ->done should be set to a wb_completion defined using the following
79 * macro. Once all work items are issued with wb_queue_work(), the caller
80 * can wait for the completion of all using wb_wait_for_completion(). Work
81 * items which are waited upon aren't freed automatically on completion.
82 */
83 #define WB_COMPLETION_INIT(bdi) __WB_COMPLETION_INIT(&(bdi)->wb_waitq)
84
85 #define DEFINE_WB_COMPLETION(cmpl, bdi) \
86 struct wb_completion cmpl = WB_COMPLETION_INIT(bdi)
87
88 /*
89 * Each wb (bdi_writeback) can perform writeback operations, is measured
90 * and throttled, independently. Without cgroup writeback, each bdi
91 * (bdi_writeback) is served by its embedded bdi->wb.
92 *
93 * On the default hierarchy, blkcg implicitly enables memcg. This allows
94 * using memcg's page ownership for attributing writeback IOs, and every
95 * memcg - blkcg combination can be served by its own wb by assigning a
96 * dedicated wb to each memcg, which enables isolation across different
97 * cgroups and propagation of IO back pressure down from the IO layer upto
98 * the tasks which are generating the dirty pages to be written back.
99 *
100 * A cgroup wb is indexed on its bdi by the ID of the associated memcg,
101 * refcounted with the number of inodes attached to it, and pins the memcg
102 * and the corresponding blkcg. As the corresponding blkcg for a memcg may
103 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb
104 * is tested for blkcg after lookup and removed from index on mismatch so
105 * that a new wb for the combination can be created.
106 */
107 struct bdi_writeback {
108 struct backing_dev_info *bdi; /* our parent bdi */
109
110 unsigned long state; /* Always use atomic bitops on this */
111 unsigned long last_old_flush; /* last old data flush */
112
113 struct list_head b_dirty; /* dirty inodes */
114 struct list_head b_io; /* parked for writeback */
115 struct list_head b_more_io; /* parked for more writeback */
116 struct list_head b_dirty_time; /* time stamps are dirty */
117 spinlock_t list_lock; /* protects the b_* lists */
118
119 struct percpu_counter stat[NR_WB_STAT_ITEMS];
120
121 unsigned long congested; /* WB_[a]sync_congested flags */
122
123 unsigned long bw_time_stamp; /* last time write bw is updated */
124 unsigned long dirtied_stamp;
125 unsigned long written_stamp; /* pages written at bw_time_stamp */
126 unsigned long write_bandwidth; /* the estimated write bandwidth */
127 unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */
128
129 /*
130 * The base dirty throttle rate, re-calculated on every 200ms.
131 * All the bdi tasks' dirty rate will be curbed under it.
132 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
133 * in small steps and is much more smooth/stable than the latter.
134 */
135 unsigned long dirty_ratelimit;
136 unsigned long balanced_dirty_ratelimit;
137
138 struct fprop_local_percpu completions;
139 int dirty_exceeded;
140 enum wb_reason start_all_reason;
141
142 spinlock_t work_lock; /* protects work_list & dwork scheduling */
143 struct list_head work_list;
144 struct delayed_work dwork; /* work item used for writeback */
145
146 unsigned long dirty_sleep; /* last wait */
147
148 struct list_head bdi_node; /* anchored at bdi->wb_list */
149
150 #ifdef CONFIG_CGROUP_WRITEBACK
151 struct percpu_ref refcnt; /* used only for !root wb's */
152 struct fprop_local_percpu memcg_completions;
153 struct cgroup_subsys_state *memcg_css; /* the associated memcg */
154 struct cgroup_subsys_state *blkcg_css; /* and blkcg */
155 struct list_head memcg_node; /* anchored at memcg->cgwb_list */
156 struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */
157
158 union {
159 struct work_struct release_work;
160 struct rcu_head rcu;
161 };
162 #endif
163 };
164
165 struct backing_dev_info {
166 u64 id;
167 struct rb_node rb_node; /* keyed by ->id */
168 struct list_head bdi_list;
169 unsigned long ra_pages; /* max readahead in PAGE_SIZE units */
170 unsigned long io_pages; /* max allowed IO size */
171
172 struct kref refcnt; /* Reference counter for the structure */
173 unsigned int capabilities; /* Device capabilities */
174 unsigned int min_ratio;
175 unsigned int max_ratio, max_prop_frac;
176
177 /*
178 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are
179 * any dirty wbs, which is depended upon by bdi_has_dirty().
180 */
181 atomic_long_t tot_write_bandwidth;
182
183 struct bdi_writeback wb; /* the root writeback info for this bdi */
184 struct list_head wb_list; /* list of all wbs */
185 #ifdef CONFIG_CGROUP_WRITEBACK
186 struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */
187 struct mutex cgwb_release_mutex; /* protect shutdown of wb structs */
188 struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */
189 #endif
190 wait_queue_head_t wb_waitq;
191
192 struct device *dev;
193 char dev_name[64];
194 struct device *owner;
195
196 struct timer_list laptop_mode_wb_timer;
197
198 #ifdef CONFIG_DEBUG_FS
199 struct dentry *debug_dir;
200 #endif
201 };
202
203 enum {
204 BLK_RW_ASYNC = 0,
205 BLK_RW_SYNC = 1,
206 };
207
208 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
209 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
210
211 struct wb_lock_cookie {
212 bool locked;
213 unsigned long flags;
214 };
215
216 #ifdef CONFIG_CGROUP_WRITEBACK
217
218 /**
219 * wb_tryget - try to increment a wb's refcount
220 * @wb: bdi_writeback to get
221 */
wb_tryget(struct bdi_writeback * wb)222 static inline bool wb_tryget(struct bdi_writeback *wb)
223 {
224 if (wb != &wb->bdi->wb)
225 return percpu_ref_tryget(&wb->refcnt);
226 return true;
227 }
228
229 /**
230 * wb_get - increment a wb's refcount
231 * @wb: bdi_writeback to get
232 */
wb_get(struct bdi_writeback * wb)233 static inline void wb_get(struct bdi_writeback *wb)
234 {
235 if (wb != &wb->bdi->wb)
236 percpu_ref_get(&wb->refcnt);
237 }
238
239 /**
240 * wb_put - decrement a wb's refcount
241 * @wb: bdi_writeback to put
242 */
wb_put(struct bdi_writeback * wb)243 static inline void wb_put(struct bdi_writeback *wb)
244 {
245 if (WARN_ON_ONCE(!wb->bdi)) {
246 /*
247 * A driver bug might cause a file to be removed before bdi was
248 * initialized.
249 */
250 return;
251 }
252
253 if (wb != &wb->bdi->wb)
254 percpu_ref_put(&wb->refcnt);
255 }
256
257 /**
258 * wb_dying - is a wb dying?
259 * @wb: bdi_writeback of interest
260 *
261 * Returns whether @wb is unlinked and being drained.
262 */
wb_dying(struct bdi_writeback * wb)263 static inline bool wb_dying(struct bdi_writeback *wb)
264 {
265 return percpu_ref_is_dying(&wb->refcnt);
266 }
267
268 #else /* CONFIG_CGROUP_WRITEBACK */
269
wb_tryget(struct bdi_writeback * wb)270 static inline bool wb_tryget(struct bdi_writeback *wb)
271 {
272 return true;
273 }
274
wb_get(struct bdi_writeback * wb)275 static inline void wb_get(struct bdi_writeback *wb)
276 {
277 }
278
wb_put(struct bdi_writeback * wb)279 static inline void wb_put(struct bdi_writeback *wb)
280 {
281 }
282
wb_dying(struct bdi_writeback * wb)283 static inline bool wb_dying(struct bdi_writeback *wb)
284 {
285 return false;
286 }
287
288 #endif /* CONFIG_CGROUP_WRITEBACK */
289
290 #endif /* __LINUX_BACKING_DEV_DEFS_H */
291
